Keyword: cavity
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SUPCAV002 Ex-Situ Investigation of the Effects of Heating Rate on the Recrystallization in Rolled Polycrystals of High-Purity Niobium ECR, niobium, SRF, electron 1
 
  • Z.L. Thune, N. Fleming, C. McKinney, E.M. Nicometo
    MSU, East Lansing, USA
  • S. Balachandran
    NHMFL, Tallahassee, Florida, USA
  • T.R. Bieler
    Michigan State University, East Lansing, Michigan, USA
 
  Funding: US Dept. of Energy award DE-SC0009960
The consistent production of high-purity niobium cavities for superconducting radiofrequency (SRF) applications is crucial for enabling improvements in accelerator performance. Recent work has shown that dislocations and grain boundaries trap magnetic flux which dissipates energy and degrades cavity performance. We hypothesize that the current heating rate used in production is too slow and therefore facilitates recovery rather than recrystallization. Recovery, unlike recrystallization, does not reduce the number of geometrically necessary dislocations (GNDs) that are strongly correlated to trapped magnetic flux. Using excess high-purity niobium saved from the production of a cavity, the material was divided into two groups and rolled to ~30% reduction with half rolled parallel to the original rolling direction, and the other half rolled perpendicular. To examine the effect of heating rate, samples were encapsulated in quartz tubes and placed into either a preheated furnace or a cold furnace to allow for heat treatments at different rates. Then using ex-situ electron backscatter diffraction (EBSD) mapping, the extent of recrystallization was determined.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV002  
About • Received ※ 22 June 2021 — Revised ※ 31 August 2021 — Accepted ※ 16 November 2021 — Issue date ※ 20 February 2022
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SUPCAV003 Dynamic Temperature Mapping of Nb3Sn Cavities SRF, site, multipactoring, accelerating-gradient 6
 
  • R.D. Porter, N. Banerjee, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Niobium-3 Tin (Nb3Sn) is the most promising alternative material to niobium for SRF accelerator cavities. The material promises nearly twice the potential accelerating gradients (~100 MV/m in TESLA elliptical cavities), increased quality factors, and 4.2 K operation. Current state of the art Nb3Sn cavities reach quality factors of 2 x 1010 at 4.2 K and have reached 24 MV/m. Determining the cause of the premature field limitation is the topic of ongoing research. Cornell University has recently developed a high-speed temperature mapping system that can examine cavity quench mechanisms in never before achieved ways. Here we present high-speed temperature map results of Nb3Sn cavities and examine the quench mechanism and dynamic heating. We show an initial multipacting quench and sudden temperature jumps at multiple locations on the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV003  
About • Received ※ 09 July 2021 — Accepted ※ 12 August 2021 — Issue date; ※ 31 August 2021  
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SUPCAV005 Current Status of the ALPI Linac Upgrade for the SPES Facilities at INFN LNL linac, acceleration, niobium, experiment 11
 
  • A. Tsymbaliuk, D. Bortolato, F. Chiurlotto, E. Chyhyrynets, G. Keppel, E. Munaron, C. Pira, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • E. Chyhyrynets
    Università degli Studi di Padova, Padova, Italy
  • A. Tsymbaliuk
    UNIFE, Ferrara, Italy
 
  The SPES project is based at INFN LNL and covers basic research in nuclear physics, radionuclide production, materials science research, nuclear technology and medicine. The Radioactive Ion Beam (RIB) produced by SPES will be accelerated by ALPI, which is a linear accelerator, equipped with superconducting quarter wave resonators (QWRs) and operating at LNL since 1990. For RIB acceleration it is mandatory to perform an upgrade of ALPI which consists of the implementation of two additional cryostats, containing 4 accelerating cavities each, in the high-ß section. The QWRs production technology is well established. The production technology of Nb/Cu QWRs should be adjusted for high-ß cavities production. In the framework of the upgrade, several vacuum systems were refurbished, optimal parameters of the biased sputtering processes of copper QWR cavities and plates were defined. The process of mechanical and chemical preparation, sputtering and cryogenic measurement of the high-ß Nb/Cu QWR cavities were adjusted. Several QWR cavities were already produced and measured. Currently, the production of the Nb/Cu sputtered QWR cavities and plates is ongoing.  
poster icon Poster SUPCAV005 [0.938 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV005  
About • Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 29 April 2022
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SUPCAV006 Cavity Designs for the CH3 to CH11 of the Superconducting Heavy Ion Accelerator HELIAC heavy-ion, linac, simulation, solenoid 15
 
  • T. Conrad, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher, J. List
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, M. Basten, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • S. Lauber
    KPH, Mainz, Germany
 
  Funding: BMBF
In collaboration of GSI, HIM and IAP Frankfurt, the superconducting linear accelerator HELIAC is being built at GSI. The cw-mode operated linac with a final energy of 7.3 MeV/u at a mass-to-charge ratio of A/q=6 and a frequency of 216.816 MHz is intended for various experiments, especially with heavy ions at energies close to the Coulomb barrier for the research of SHE. The planned linac consists of 4 cryostats, 4 superconducting bunchers, 4 solenoids and 12 superconducting CH-cavities. After successful beam tests with CH0 and high frequency tests with CH1 and CH2, CH3 to CH11 will be designed. Based on previous experience and successful test results, individual optimizations of the cavity design will be performed. Attention has been paid to reducing production costs by designing as many components as possible, such as spokes or the tank caps with the same geometries. Despite this cost reduction, it was possible to improve the theoretical performance in the simulations. In addition, a test bench is being developed which will be used for the first-time investigation of the mechanical stability, possible material fatigue and the durability of the dynamic bellows tuners.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV006  
About • Received ※ 21 June 2021 — Accepted ※ 21 October 2021 — Issue date; ※ 12 November 2021  
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SUPCAV007 Thick Film Morphology and SC Characterizations of 6 GHz Nb/Cu Cavities niobium, SRF, superconductivity, site 18
 
  • V.A. Garcia Diaz, O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello, M. Zanierato
    INFN/LNL, Legnaro (PD), Italy
  • E. Chyhyrynets
    Università degli Studi di Padova, Padova, Italy
  • D. Fonnesu
    CERN, Meyrin, Switzerland
  • O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • M. Vogel
    University Siegen, Siegen, Germany
 
  Funding: European Union’s H2020 Framework Programme under Grant Agreement no. 764879
Thick films deposited in long pulse DCMS mode onto 6 GHz copper cavities have demonstrated the mitigation of the Q-slope at low accelerating fields. The Nb thick films (~40 microns) show the possibility to reproduce the bulk niobium superconducting properties and morpholo-gy characterizations exhibited dense and void-free films that are encouraging for the scaling of the process to 1.3 GHz cavities. In this work a full characterization of thick films by DC magnetometry, computer tomography, SEM and RF characterizations are presented.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV007  
About • Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 16 February 2022 — Issue date ※ 08 April 2022
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SUPCAV008 Design and Construction of Nb3Sn Vapor Diffusion Coating System at KEK vacuum, radio-frequency, MMI, operation 23
 
  • K. Takahashi, T. Okada
    Sokendai, Ibaraki, Japan
  • H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  Vapor diffusion Nb3Sn coating system was developed at KEK. At most 1.3GHz 3-cell cavity can be coat with the coating system. The coating system consists of a coating chamber made of Nb, a vacuum furnace for heating the Nb chamber, and a heating device of Tin in the crucible. The Nb chamber vacuum and the furnace vacuum are isolated to prevent contamination from the furnace. There is a heating device for increasing Tin vapor pressure. In this presentation, the design and construction of the coating system are reported.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV008  
About • Received ※ 21 June 2021 — Accepted ※ 18 November 2021 — Issue date; ※ 11 April 2022  
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SUPCAV009 First Nb3Sn Coating and Cavity Performance Result at KEK SRF, radio-frequency, experiment, superconducting-RF 27
 
  • K. Takahashi, T. Okada
    Sokendai, Ibaraki, Japan
  • H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  At KEK, Nb3Sn vapor diffusion R&D for High-Q has just started. We have performed Nb3Sn coating on niobium samples and characterized these samples. We optimized the cavity coating parameter from the result of characterized samples. After optimizing the parameter, we have performed Nb3Sn coating on a TESLA-like single-cell Nb cavity and measured cavity performance in vertical tests. This presentation presents the result of the cavity coating and performance results.  
poster icon Poster SUPCAV009 [1.477 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV009  
About • Received ※ 21 June 2021 — Accepted ※ 18 March 2022 — Issue date; ※ 16 May 2022  
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SUPCAV010 Design of Third-Harmonic Superconducting Cavity for Shen-Zhen Industry Synchrotyon Radiation Source7 superconducting-cavity, acceleration, accelerating-gradient, electron 32
 
  • N. Yuan, L. Lu, W. Ma
    Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
  • L.G. Liu
    SINAP, Shanghai, People’s Republic of China
  • L. Yang, Z. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Shenzhen industry synchrotron radiation source is the fourth generation of medium energy light source with beam energy of 3GeV. It has the characteristics of low emittance and high brightness. In the design, the beam lifetime is one of the most important parameters. The main factor that affects its beam lifetime is the scattering of electron collisions inside the beam. To solve this problem, a harmonic radio frequency system is used. The third harmonic superconducting elliptical cavity is de-signed to stretch beam length to improve beam quality and beam lifetime. The present work is mainly about the shape optimization of 1.5 GHz 2-cell third harmonic superconducting elliptical cavity. Firstly, the principle of harmonic cavity in dual high frequency system is introduced, and the resonant frequency and acceleration gradient of superconducting cavity are given. Then, CST, electromagnetic field simulation software is used to optimize the cavity parameters to obtain the high performance and high frequency parameters that meet the requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV010  
About • Received ※ 21 June 2021 — Revised ※ 21 November 2021 — Accepted ※ 18 February 2022 — Issue date ※ 03 May 2022
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SUPCAV011 Third Harmonic Superconductive Cavity for Bunch Lengthening and Beam Lifetime Increase of Sirius Synchrotron Light Source impedance, electron, synchrotron, beam-loading 37
 
  • I. Carvalho de Almeida, M. Hoffmann Wallner, A. Pontes Barbosa Lima
    CNPEM, Campinas, SP, Brazil
 
  A passive third harmonic superconducting cavity is to be installed at Sirius’ 4th generation synchrotron light source in order to lengthen the bunches and improve beam lifetime, which is dominated by Touschek scattering. A study of optimal bunch lengthening is carried on by enforcing a flat potential well around the synchronous electron and the results are compared to the passive operation case for several shunt impedances and unloaded quality factors based on known operating cavities. To determine the new bunch shape due to beam loading and its length, a full consistent approach is followed by setting the harmonic voltage amplitude equal to the optimum value and calculating the required detune, harmonic phase and synchronous phase for an initial complex form factor, allowing the new distribution to be obtained by an iterative process. For each case analyzed, energy acceptance is obtained through the separatrix in the phase plane and the corresponding lifetime increase ratio is calculated. Input power required after the addition of the harmonic cavity is then estimated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV011  
About • Received ※ 20 June 2021 — Accepted ※ 15 November 2021 — Issue date; ※ 21 March 2022  
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SUPCAV014 Design and Simulation of 500 MHz Single Cell Superconducting Cavity superconducting-cavity, HOM, simulation, ECR 46
 
  • Y.B. Sun, W. Ma
    Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
  • L.G. Liu
    SSRF, Shanghai, People’s Republic of China
  • L. Lu, L. Yang, Z. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: Work supported by Shenzhen Development and Reform Commis-sion
The Shenzhen Industrial Synchrotron Radiation Light Source is a fourth-generation medium-energy light source with a 3GeV storage ring electron energy and an emit-tance less than 100 pm·rad. In order to ensure the long-term stable and efficient operation of the light source, a new type of 500 MHz single-cell superconducting cavity was designed in this study to be used as a pre-research superconducting cavity for the Light Source. The 500 MHz superconducting cavity has a large beam aperture and low high order modes (HOMs) impedance, which can be used in accelerators with larger currents. In this design, we simply adopted the same design scheme as the KEKB-type and CESR-type superconducting cavity. Using CST electromagnetic field simulation software to calculate and simulate the characteristics of the cavity, the results show that the designed 500 MHz single-cell cavity can meet the requirements of a high acceleration gradient, a high r/Q value, and a low peak surface field.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV014  
About • Received ※ 21 June 2021 — Revised ※ 07 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 05 May 2022
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SUPCAV016 Studies on the Fundamental Mechanisms of Niobium Electropolishing niobium, SRF, electron, experiment 50
 
  • E.A.S. Viklund, D.N. Seidman
    NU, Evanston, Illinois, USA
  • L. Grassellino, S. Posen, T.J. Ring
    Fermilab, Batavia, Illinois, USA
 
  To improve the superconducting performance of niobium SRF cavities, electropolishing (EP) with a sulfuric and hydroflouric acid mixture is used. The chemistry of this reaction is complex due to the interactions between diffusion mechanisms, surface oxide structure, and multiple chemical species. Past studies on the EP process have produced a certain set of optimum parameters that have been used successfully for a long time. However, two recent developments have called the efficacy of the existing EP process into question. Since the introduction of nitrogen doping the surface quality of some cavities has been very poor. Also, EP performed at colder than standard temperatures leads to an increase in the cavity performance. To understand these questions, we perform a multivariate study on the EP process using niobium test samples electropolished at different temperatures and potentials. We find that electropolishing at lower potentials leads to rough surface features such as pitting and grain etching. Some of the surface features show similarities to features seen in niobium cavities. The effect of electropolishing temperature is not clear based on the results of this study.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV016  
About • Received ※ 22 June 2021 — Revised ※ 21 August 2021 — Accepted ※ 29 September 2021 — Issue date ※ 15 November 2021
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SUPCAV018 First N-Doping and Mid-T Baking of Medium-ß 644 MHz 5-Cell Elliptical Superconducting RF Cavities for Michigan State University’s Facility for Rare Isotope Beams cathode, SRF, linac, cryomodule 53
 
  • K.E. McGee, S.H. Kim, P.N. Ostroumov, A. Taylor
    FRIB, East Lansing, Michigan, USA
  • G.V. Eremeev, M. Martinello, A.V. Netepenko
    Fermilab, Batavia, Illinois, USA
  • M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by the 2020 US DoE, Office of Science Graduate Student Research award (SCGSR), and US DoE, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362
Two hadron linacs currently under development in the US, the PIP-II linac at Fermi National Accelerator Laboratory (FNAL) and the upgrade for Michigan State University’s Facility For Rare Isotope Beams (FRIB), will employ 650 and 644 MHz ß-0.6 elliptical superconducting cavities respectively to meet their design energy requirements. The desired CW operation modes of these two linacs sets Q-factor requirements well above any previously achieved for cavities at this operating frequency and velocity, driving the need to explore new high-Q treatments. The N-doping technique developed at FNAL and employed at an industrial scale to the LCLS-II cryomodules is a strong candidate for high-Q treatments, but work is needed to refine the treatment to the lower operating frequency and velocity regime. We present the first results of the first N-doping tests and a "mid-T" bake test in the FRIB 644 MHz 5-cell elliptical cavities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPCAV018  
About • Received ※ 23 June 2021 — Revised ※ 16 November 2021 — Accepted ※ 08 May 2022 — Issue date ※ 08 May 2022
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SUPFDV001 Update on Nitrogen Infusion Sample R&D at DESY niobium, vacuum, superconductivity, SRF 57
 
  • C. Bate, A. Dangwal Pandey, A. Ermakov, B. Foster, T.F. Keller, D. Reschke, J. Schaffran, S. Sievers, H. Weise, M. Wenskat
    DESY, Hamburg, Germany
  • B. Foster
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Many accelerator projects such as the European XFEL cw upgrade or the ILC, would benefit from cavities with reduced surface resistance (high Q-values) while maintaining a high accelerating gradient. A possible way to meet the requirements is the so-called nitrogen-infusion procedure on Niobium cavities. However, a fundamental understanding and a theoretical model of this method are still missing. The approach shown here is based on R\&D using small samples, with the goal of identifying all key parameters of the process and establishing a stable, reproducible recipe. To understand the underlying processes of the surface evolution that give improved cavity performance, advanced surface-analysis techniques (e.g. SEM/EDX, TEM, XPS, TOF-SIMS) are utilized and several kinds of samples are analyzed. Furthermore, parameters such as RRR and the surface critical magnetic field denoted as Hc3 have been investigated. For this purpose, a small furnace dedicated to sample treatment was set up to change and explore the parameter space of the infusion recipe. Results of these analyses and their implications for the R\&D on cavities are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV001  
About • Received ※ 22 June 2021 — Accepted ※ 03 January 2022 — Issue date; ※ 27 April 2022  
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SUPFDV002 Ab Initio Theory of the Impact of Grain Boundaries on the Superconducting Properties of Nb3Sn SRF, electron, niobium, site 62
 
  • M.M. Kelley, T. Arias, N. Sitaraman
    Cornell University, Ithaca, New York, USA
 
  Funding: This work was supported by the US National Science Foundation under award PHY-1549132, the Center for Bright Beams.
For over 50 years experiments have repeatedly demonstrated that the superconducting performance of Nb3Sn is profoundly sensitive to grain boundaries (GBs), but only recently has a microscopic theory emerged. Here we present the first comprehensive, ab initio study of GBs in Nb3Sn*. While most conventional superconductors, such as Nb, are not significantly impacted by GBs, Nb3Sn is much more sensitive to defects and disorder owing to its short coherence length of ~3 nm. Indeed, experiments suggest a link between GB stoichiometry and the performance of Nb3Sn superconducting radio frequency (SRF) cavities, and mesoscopic simulations point to GBs as a candidate mechanism that lowers the vortex-entry field in Nb3Sn SRF cavities. Our density-functional theory (DFT) calculations on tilt and twist GBs provide direct insight into antisite defect formation near GBs and how local electronic properties are impacted by clean GBs and by GBs with added point defects. Ultimately, we will show how GB composition affects the local Tc around GBs in Nb3Sn to elucidate recent SRF experiments and provide insight on promising modifications to the growth procedure of Nb3Sn to optimize its SRF performance.
[*] Michelle M Kelley et al 2021 Supercond. Sci. Technol. 34 015015
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV002  
About • Received ※ 01 July 2021 — Accepted ※ 02 December 2021 — Issue date; ※ 09 April 2022  
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SUPFDV003 Effect of Mean Free Path on Nonlinear Losses of Trapped Vortices Driven by a RF Field Field ECR, radio-frequency, linear-dynamics, simulation 67
 
  • M.R.P. Walive Pathiranage, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
 
  Funding: This work was supported by NSF under Grants PHY 100614-010 and PHY 1734075, and by DOE under Grant DE-SC 100387-020.
We report extensive numerical simulations on nonlinear dynamics of a trapped elastic vortex under rf field, and its dependence on electron mean free path li. Our calculations of the field-dependent residual surface resistance Ri(H) take into account the vortex line tension, the linear Bardeen-Stephen viscous drag and random distributions of pinning centers. We showed that Ri(H) decreases significantly at small fields as the material gets dirtier while showing field independent behavior at higher fields for clean and dirty limit. At low frequencies Ri(H) increases smoothly with the field amplitude at small H and levels off at higher fields. The mean free path dependency of viscosity and pinning strength can result in a nonmonotonic mean free path dependence of Ri, which decreases with li at higher fields and weak pinning strength.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV003  
About • Received ※ 20 June 2021 — Accepted ※ 19 December 2021 — Issue date; ※ 09 April 2022  
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SUPFDV006 Investigation of SIS Multilayer Films at HZB SRF, superconductivity, radio-frequency, quadrupole 72
 
  • D.B. Tikhonov, S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • E. Chyhyrynets, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • S.B. Leith, M. Vogel
    University Siegen, Siegen, Germany
 
  Funding: The manufacture of the QPR samples received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 730871
The systematic study of multilayer SIS films (Superconductor-Insulator-Superconductor) is being conducted in Helmholtz-Zentrum Berlin. Such films theoretically should boost the performance of superconducting cavities, and reduce some problems related to bulk Nb such as magnetic flux trapping. Up to now such films have been presented in theory, but the RF performance of those structures have not been widely studied. In this contribution we present the results of the latest tests of AlN-NbN films, deposited on micrometers-thick Nb layers on copper. It has, also, been shown previously at HZB that such SIS films may show some unexpected behavior in surface resistance versus temperature parameter space. In this contribution we continue to investigate those effects with the variation of different parameters of films (such as insulator thickness) and production recipes.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV006  
About • Received ※ 21 June 2021 — Revised ※ 09 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 21 December 2021
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SUPFDV007 Magnetic Field Penetration of Niobium Thin Films Produced by the ARIES Collaboration dipole, site, SRF, controls 77
 
  • D.A. Turner
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • G. Burt, K.D. Dumbell, O.B. Malyshev, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
  • E. Chyhyrynets, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • T. Junginger
    TRIUMF, Vancouver, Canada
  • T. Junginger
    UVIC, Victoria, Canada
  • S.B. Leith, M. Vogel
    University Siegen, Siegen, Germany
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A. Medvids
    Riga Technical University, Riga, Latvia
  • R. Ries
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
  • E. Seiler
    IEE, Bratislava, Slovak Republic
  • A. Sublet
    CERN, Meyrin, Switzerland
  • J.T.G. Wilson
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  Superconducting (SC) thin film coatings on Cu substrates are already widely used as an alternative to bulk Nb SRF structures. Using Cu allows improved thermal stability compared to Nb due to having a greater thermal conductivity. Niobium thin film coatings also reduce the amount of Nb required to produce a cavity. The performance of thin film Nb cavities is not as good as bulk Nb cavities. The H2020 ARIES WP15 collaboration studied the impact of substrate polishing and the effect produced on Nb thin film depositions. Multiple samples were produced from Cu and polished with various techniques. The polished Cu substrates were then coated with a Nb film at partner institutions. These samples were characterised with surface characterisation techniques for film morphology and structure. The SC properties were studied with 2 DC techniques, a vibrating sample magnetometer (VSM) and a magnetic field penetration (MFP) facility. The results conclude that both chemical polishing and electropolishing produce the best DC properties in the MFP facility. A comparison between the VSM and the MFP facility can be made for 10 micron thick samples, but not for 3 micron thick samples.  
poster icon Poster SUPFDV007 [1.059 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV007  
About • Received ※ 21 June 2021 — Accepted ※ 28 October 2021 — Issue date; ※ 09 April 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPFDV009 Thermal Annealing of Sputtered Nb3Sn and V3Si Thin Films for Superconducting RF Cavities SRF, ECR, radio-frequency, target 82
 
  • K. Howard, M. Liepe, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams and Cornell Center for Materials Research Shared Facilities supported through the NSF MRSEC program (DMR-1719875)
Nb3Sn and V3Si thin films are alternative material candidates for the next-generation of superconducting radio frequency (SRF) cavities. However, past sputtered films suffer from stoichiometry and strain issues during deposition and post annealing. As such, we aim to explore the structural and chemical effects of thermal annealing, both in-situ and post-sputtering, on DC-sputtered Nb3Sn and V3Si with varying thickness on Nb or Cu substrates. We successfully enabled recrystallization of 100 nm thin Nb3Sn films with stoichiometric and strain-free grains at 950 C annealing. For 2 um films, we observed removal of strain and slight increase in grain size with increasing temperature. A phase transformation from unstable to stable structure appeared on thick V3Si samples, while we observed significant Sn loss in thick Nb3Sn films at high temperature anneals. For films on Cu substrates, we observed similar Sn and Si loss during annealing likely due to Cu-Sn and Cu-Si phase generation and subsequent Sn and Si evaporation. These results encourage us to refine our process to obtain high quality films for SRF use.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV009  
About • Received ※ 22 June 2021 — Revised ※ 06 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 17 March 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPFDV012 The Development of HiPIMS Multilayer SIS Film Coatings on Copper for SRF Applications site, SRF, lattice, shielding 86
 
  • S.B. Leith, X. Jiang, A.O. Sezgin, M. Vogel
    University Siegen, Siegen, Germany
  • B. Butz, Y. Li, J. Müller
    MNaF, Siegen, Germany
  • S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
 
  Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871
In recent years, the use of alternatives to bulk Nb in the fabrication of SRF cavities, including novel materials and/or fabrication techniques, have been extensively explored by the SRF community. One of these new methodologies is the use of a superconductor-insulator-superconductor (SIS) multilayer structure. Typically, these have been envisaged for use with bulk Nb cavities. However, it is conceivable to combine the benefits of SIS structures with the benefits of coated Cu cavities. It is also clear that the use of energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS), provide significant benefits over typical DC magnetron sputtering (MS) coatings, in terms of SRF performance. In light of this, two series of multilayer SIS film coatings, with a Nb-AlN-NbN structure, were deposited onto electropolished OFHC Cu samples, with the use of HiPIMS, in order to determine the efficacy of this approach. This contribution details the development of these coatings and the required optimization of the coating parameters of the separate material systems, through the use of multiple material and superconducting characterization techniques.
 
poster icon Poster SUPFDV012 [2.056 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV012  
About • Received ※ 20 June 2021 — Accepted ※ 21 December 2021 — Issue date; ※ 27 April 2022  
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SUPFDV013 HiPIMS NbN Thin Film Development for Use in Multilayer SIS Films site, cathode, lattice, ECR 91
 
  • S.B. Leith, B. Bai, X. Jiang, M. Vogel
    University Siegen, Siegen, Germany
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
 
  Funding: Authors acknowledge both the EASITrain, Marie Sklodowska-Curie Action (MSCA) Innovative Training Network (ITN), Grant Agreement no. 764879 and the ARIES collaboration, Grant Agreement no. 730871
As part of efforts to improve the performance of SRF cavities, the use of alternative structures, such as superconductor-insulator-superconductor (SIS) film coatings have been extensively investigated. Initial efforts using DC magnetron sputtering (MS) deposited NbN films showed the efficacy of this approach. The use of energetic condensation methods, such as high power impulse magnetron sputtering (HiPIMS), have already improved the performance of Nb thin films for SRF cavities and have already been used for nitride film coatings in the tool industry. In this contribution, the results from the deposition of HiPIMS NbN thin films onto oxygen free high conductivity (OFHC) Cu substrates are presented. The effects of the different deposition parameters on the deposited films were elucidated through various characterisation methods, resulting in an optimum coating procedure. This allowed for further comparison between the HiPIMS NbN films and the previously presented DC MS NbN films. The results indicate the improvements offered by HiPIMS deposition, most notably, the significant increase in the entry field, and its applicability to the deposition of SIS films on Cu.
 
poster icon Poster SUPFDV013 [0.918 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV013  
About • Received ※ 20 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 25 October 2021
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SUPFDV015 Preliminary Results from Magnetic Field Scanning System for a Single-Cell Niobium Cavity SRF, niobium, experiment, MMI 96
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
 
  One of the building blocks of modern particle accelerators is superconducting radiofrequency (SRF) cavities. Niobium is the material of choice to build such cavities, which operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. There are several sources of residual losses, one of them is trapped magnetic flux, which limits the quality factor in SRF cavities. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic flux trapping. A magnetic field scanning system (MFSS) for SRF cavities using Hall probes and Fluxgate magnetometer has been designed, built, and is commissioned to measure the local magnetic field trapped in 1.3 GHz single-cell SRF cavities at 4 K. In this contribution, we will present the preliminary results from MFSS for a single cell niobium cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV015  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 08 November 2021 — Issue date ※ 27 April 2022
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SUPFDV016 A Low Power Test Facility for SRF Thin Film Testing with High Sample Throughput Rate SRF, niobium, controls, pick-up 100
 
  • D.J. Seal
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • G. Burt, P. Goudket, O.B. Malyshev, B.S. Sian, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt, B.S. Sian
    Lancaster University, Lancaster, United Kingdom
  • J.A. Conlon, P. Goudket, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  A low-power SRF test facility is being upgraded at Daresbury Laboratory as part of the superconducting thin film testing programme. The facility consists of a bulk niobium test cavity operating at 7.8 GHz, surrounded by RF chokes, and can be run with input RF powers up to 1 W. It is housed within a liquid helium free cryostat and is able to test thin film planar samples up to 100 mm in diameter with a thickness between 1 and 20 mm. The RF chokes allow the cavity to be physically and thermally isolated from the sample, thus reducing the need for complicated sample mounting, whilst minimising field leakage out of the cavity. This allows for a fast turnaround time of two to three days per sample. Initial tests using a newly designed sample holder have shown that an RF-DC compensation method can be used successfully to calculate the surface resistance of samples down to 4 K. Potential upgrades include a pick-up antenna for direct measurements of stored energy and the addition of a self-excited loop to mitigate the effects of microphonics. Details of this facility and preliminary results are described in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV016  
About • Received ※ 21 June 2021 — Accepted ※ 12 August 2021 — Issue date; ※ 18 December 2021  
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SUPFDV018 CERN Based Tc Measurement Station for Thin-Film Coated Copper Samples and Results on Related Studies niobium, SRF, site, pick-up 105
 
  • D. Fonnesu, J. Bremer, T. Koettig, L. Laín-Amador, C. Pereira Carlos, G.J. Rosaz, A.P.O. Vaaranta
    CERN, Meyrin, Switzerland
 
  Funding: EASITrain - European Advanced Superconductivity Innovation and Training. This MSCA ITN has received funding from the European Union’s H2020 Framework Programme under GA no. 764879.
In the framework of The Future Circular Collider (FCC) Study, the development of thin-film coated superconducting radio-frequency (SRF) cavities capable of providing higher accelerating fields (10 to 20 MV/m against 5 MV/m of LHC) represents a major challenge. In this work, we present the development of a test stand commissioned at CERN for the inductive measurement of the critical temperature (Tc) of SC thin-film deposited on copper samples for SRF applications. Based on new studies for the production of Non Evaporable Getters (NEG) coated chambers [1], we also present the first results of an alternative forming method for seamless copper cavities with niobium layer integrated in the production process.
[1] doi:10.1116/1.4999539
 
poster icon Poster SUPFDV018 [1.611 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV018  
About • Received ※ 21 June 2021 — Revised ※ 09 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 01 May 2022
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SUPFDV020 ALD-Based NbIiN Studies for SIS R&D site, plasma, SRF, vacuum 109
 
  • I. González Díaz-Palacio, R.H. Blick, R. Zierold
    University of Hamburg, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Superconductor-Insulator-Superconductor multilayers improve the performance of SRF cavities providing magnetic screening of the bulk cavity and lower surface resistance. In this framework NbTiN mixtures stand as a potential material of interest. Atomic layer deposition (ALD) allows for uniform coating of complex geometries and enables tuning of the stoichiometry and precise thickness control in sub-nm range. In this talk, we report about NbTiN thin films deposited by plasma-enhanced ALD on insulating AlN buffer layer. The deposition process has been optimized by studying the superconducting electrical properties of the films. Post-deposition thermal annealing studies with varying temperatures, annealing times, and gas atmospheres have been performed to further improve the thin film quality and the superconducting properties. Our experimental studies show an increase in Tc by 87.5% after thermal annealing and a maximum Tc of 13.9 K has been achieved for NbTiN of 23 nm thickness. Future steps include lattice characterization, using XRR/XRD/EBSD/PALS, and SRF measurements to obtain Hc1 and the superconducting gap.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV020  
About • Received ※ 22 June 2021 — Revised ※ 17 August 2021 — Accepted ※ 17 August 2021 — Issue date ※ 19 January 2022
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SUPTEV001 Magnetic Field Penetration Technique to Study High Field Shielding of Multilayered Superconductors SRF, niobium, accelerating-gradient, site 112
 
  • I.H. Senevirathne, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  Funding: NSF Grants PHY-1734075 and PHY-1416051, and DOE Awards DE-SC0010081 and DE-SC0019399
The SIS structure which consists of alternative thin layers of superconductors and insulators on a bulk niobium has been proposed to shield niobium cavity surface from high magnetic field and hence increase the accelerating gradient. The study of the behavior of multilayer super-conductors in an external magnetic field is essential to optimize their SRF performance. In this work we report the development of a simple and efficient technique to measure penetration of magnetic field into bulk, thin film and multilayer superconductors. Experimental setup contains a small superconducting solenoid which can produce a parallel surface magnetic field up to 0.5 T and Hall probes to detect penetrated magnetic field across the superconducting sample. This system was calibrated and used to study the effect of niobium sample thickness on the field of full magnetic flux penetration. We determined the optimum thickness of the niobium substrate to fabricate the multilayer structure for the measurements in our setup. This technique was used to measure penetration fields of Nb3Sn thin films and Nb3Sn/Al2O3 multi-layers deposited on Al2O3 wafers.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV001  
About • Received ※ 22 June 2021 — Revised ※ 15 August 2021 — Accepted ※ 20 September 2021 — Issue date ※ 28 April 2022
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SUPTEV002 Application of Plasma Electrolytic Polishing onto SRF Substrates cathode, SRF, plasma, power-supply 116
 
  • E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello, M. Zanierato
    INFN/LNL, Legnaro (PD), Italy
 
  Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the Euro-pean Union’s Horizon 2020 Research and Innovation programme under GA No 101004730.
A new promising approach of SRF substrates surface treatment has been studied - Plasma Electrolytic Polishing (PEP). The possible application of PEP can be used not only on conventional elliptical resonators, but also on other components of SRF such as, for example, couplers or Quadrupole resonators (QPRs). However, SRF application of PEP represents a challenge since it requires a different approach to treat the inner surface of elliptical cavities respect to electropolishing. In this work, the main problematics and possible solutions, the equipment, and the polishing system requirements will be shown. A proposed polishing system for 6 GHz elliptical cavities and QPRs will be shown and discussed.
 
poster icon Poster SUPTEV002 [2.710 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV002  
About • Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 22 April 2022
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SUPTEV003 Cu/Nb QPR Surface Preparation Protocol in the Framework of ARIES Project SRF, superconductivity, ECR, framework 121
 
  • E. Chyhyrynets, O. Azzolini, R. Caforio, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
 
  Funding: Work supported by the INFN CSNV experiment TEFEN. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Pro-gramme under Grant Agreement no. 730871.
The Quadrupole Resonator is a powerful tool for SRF R&D on thin films. It allows to perform Q vs E measurements on flat sample rather than a curved surface of a cavity. For the investigation of SC coatings on copper substrates, e-beam welded Cu/Nb samples have been prepared for the QPR. However, the presence of two metals, in particular at the interface makes proper polishing of both surfaces challenging due the different chemical behaviour of both components. In this work we present the protocol developed for surface preparation of the coexisting Cu and Nb phases and the results obtained for 5 different samples. The work was performed in the framework of the ARIES project.
 
poster icon Poster SUPTEV003 [2.506 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV003  
About • Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 12 August 2021 — Issue date ※ 27 September 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV006 Commissioning of a Calibration Device for Second Sound Quench Detection SRF, MMI, superconductivity, software 124
 
  • L. Ebeling, D. Reschke, L. Steder
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  An important part of research and development in the field of superconducting radio frequency technology is the quench detection since these breakdowns of superconductivity often limit the cavity performance. Although the second sound based quench detection is widely used, only few studies dealing with its systematic uncertainties exist. Hence, the vertical test stands at the cavity test facility of DESY were extended by calibration device prototypes in order to estimate the accuracy of this method. For the first time at DESY, artificial signals have been generated and reconstructed by heating power film resistors. These second sound signals are determined using noise canceling algorithms and the existing reconstruction software. To evaluate the reconstructed positions, the absolute distance between reconstructed and true coordinates is calculated. Thus, a first uncertainty map of the cavity surface is created to quantify the reconstruction results of actual cavity quenches including systematic effects of the quench positioning like the varying sensor coverage around the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV006  
About • Received ※ 20 June 2021 — Revised ※ 09 July 2021 — Accepted ※ 20 November 2021 — Issue date ※ 30 April 2022
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SUPTEV007 Development of a System for Coating SRF Cavities Using Remote Plasma CVD plasma, SRF, controls, vacuum 129
 
  • G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, M. Liepe, J. Sears, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the National Science Foundation under Grant No. PHY-1549132.
Next-generation, thin-film surfaces employing Nb3Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. A vacuum quality monitor (VQM) is used to characterize the residual gases before coating. The CVD system has been designed and is currently under assembly and commissioning.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV007  
About • Received ※ 09 July 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 10 February 2022  
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SUPTEV008 CW Operation of Conduction-Cooled Nb3Sn SRF Cavity SRF, operation, cryomodule, controls 133
 
  • N.A. Stilin, A.T. Holic, M. Liepe, R.D. Porter, J. Sears, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Significant progress in the performance of SRF cavities coated with Nb3Sn films during the last few years has provided an energy efficient alternative to traditional Nb cavities, thereby initiating a fundamental shift in SRF technology. These Nb3Sn cavities can operate at significantly higher temperatures than Nb cavities while simultaneously requiring less cooling power. This allows for the use of new cryogenic cooling schemes based on conduction cooling with robust, commercialized turn-key style cryocoolers. Cornell University has developed and tested a 2.6 GHz Nb3Sn cavity assembly which utilizes such cooling methods. These tests have demonstrated stable RF operation at 10 MV/m with measured thermal dynamics which match numerical simulations. These results also serve as a foundation for designing a new standalone SRF cryomodule which will use a pair of cryocoolers to cool a 1.3 GHz Nb3Sn cavity with an input coupler capable of supporting high beam current operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV008  
About • Received ※ 22 June 2021 — Accepted ※ 13 August 2021 — Issue date; ※ 08 November 2021  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV009 Development of a New B-Mapping System for SRF Cavity Vertical Tests SRF, shielding, background, radiation 137
 
  • J.C. Wolff, A. Gössel, C. Müller, D. Reschke, L. Steder, D. Tischhauser
    DESY, Hamburg, Germany
  • W. Hillert, J.C. Wolff
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Magnetic flux trapped in the Niobium bulk material of superconducting radio frequency (SRF) cavities degrades their quality factor and the accelerating gradient. The sensitivity of the cavity to trapped magnetic flux is mainly determined by the treatment, the geometry and the Niobium grain size and orientation. To potentially improve the flux expulsion characteristics of SRF cavities and hence the efficiency of future accelerator facilities, further studies of the trapping behavior are essential. For this purpose a so-called B-mapping system to monitor the magnetic flux along the outer cavity surface of 1.3 GHz TESLA-Type single-cell SRF cavities is currently under development at DESY. Contrary to former approaches, this system digitizes the sensor signals already inside of the cryostat to extensively reduce the number of required cable feedthroughs. Furthermore, the signal-to-noise ratio (SNR) and consequently the measuring sensitivity can be enhanced by shorter analog signal lines, less thermal noise and the Mu-metal shielding of the cryostat. In this contribution the design, the development process as well as first performance test results of the B-mapping system are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV009  
About • Received ※ 01 July 2021 — Accepted ※ 31 March 2022 — Issue date; ※ 09 April 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV010 Electrical and Thermal Properties of Cold-Sprayed Bulk Copper and Copper-Tungsten Samples at Cryogenic Temperatures site, SRF, vacuum, radio-frequency 142
 
  • H. Pokhrel
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, P. Dhakal, J.K. Spradlin
    JLab, Newport News, Virginia, USA
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, Solon, Ohio, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, SBIR grant DE-SC00195589
The development of high thermal conductivity coatings with pure copper or copper-tungsten alloy could be beneficial to improve the heat transfer of bulk Nb cavities for conduction cooling applications and to increase the stiffness of bulk Nb cavities cooled by liquid helium. Cold-spray is an additive manufacturing technique suitable to grow thick coatings of either Cu or CuW on a Nb substrate. Bulk (~5 mm thick) coatings of Cu and CuW were deposited on standard 3 mm thick, high-purity Nb samples and smaller samples with 2 mm x 2 mm cross section were cut for measuring the thermal conductivity and the residual resistivity ratio. The samples were subjected to annealing at different temperatures and a maximum RRR of ~130 and ~40 were measured for the Cu samples and CuW samples, respectively.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV010  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 15 November 2021 — Issue date ※ 21 March 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV011 Nb3Sn Coating of Twin Axis Cavity for SRF Applications linac, SRF, niobium, superconductivity 146
 
  • J.K. Tiskumara, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini, C.E. Reece
    JLab, Newport News, Virginia, USA
 
  The twin axis cavity with two identical accelerating beams has been proposed for energy recovery linac (ERL) applications. Nb3Sn is a superconducting material with a higher critical temperature and a higher critical field as compared to Nb, which promises a lower operating cost due to higher quality factors. Two niobium twin axis cavities were fabricated at JLab and were proposed to be coated with Nb3Sn. Due to their more complex geometry, the typical coating process used for basic elliptical cavi-ties needs to be improved to coat these cavities. This development advances the current coating system at JLab for coating complex cavities. Two twin axis cavities were coated recently for the first time. This contribution dis-cusses initial results from coating of twin axis cavities, RF testing and witness sample analysis with an overview of the current challenges towards high performance Nb3Sn coated twin axis cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV011  
About • Received ※ 22 June 2021 — Revised ※ 19 December 2021 — Accepted ※ 21 February 2022 — Issue date ※ 01 April 2022
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SUPTEV013 Validation of the 650 MHz SRF Cavity Tuner for PIP-II at 2 K SRF, linac, proton, operation 151
 
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • S.K. Chandrasekaran, S. Cheban, G.V. Eremeev, F. Furuta, T.N. Khabiboulline, Y.M. Pischalnikov, O.V. Prokofiev, A.I. Sukhanov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  The PIP-II linac will include thirty-six β=0.61 and twenty-four β=0.92 650 MHz 5 cell elliptical SRF cavities. Each cavity will be equipped with a tuning system consisting of a double lever slow tuner for coarse frequency tuning and a piezoelectric actuator for fine frequency tuning. One dressed cavity equipped with an SRF tuner has been tested in the horizontal test stand at Fermilab. Results of testing the cavity-tuner system will be presented.  
poster icon Poster SUPTEV013 [0.830 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV013  
About • Received ※ 22 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 26 February 2022 — Issue date ※ 02 May 2022
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SUPTEV014 SRF Cavity Tuners for 3.9 GHz Cryomodules for LCLS-II Project cryomodule, operation, SRF, FEL 155
 
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • T.T. Arkan, T.N. Khabiboulline, Y.M. Pischalnikov, G.V. Romanov, R.P. Stanek, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  Fermilab conducted testing of three 3.9 GHz cryomodules for the LCLS-II project that will operate in continuous wave mode. A fast/fine tuning component was added to the LCLS-II 3.9 GHz tuner design due to the cavity bandwidth of 130 Hz which consists of two encapsulated piezos. Several cavities faced problems with fast-tuner operations after cooldown to 2 K and tuning the cavities to 3.9 GHz in cryomodule 2. All the piezo actuators were in working conditions but the slow tuner ranges required to stretch some of the cavities to the operational 3.9 GHz frequency were too small to deliver the required preload on the piezos. This behavior can be attributed to several factors: setting the initial warm cavity frequency during production too high, pressure tests of the warm cryomodule could have changed cavity frequency; and the small bending and twisting of the cavity-tuner system during the cooldown and warmup of the cavities. A decision was made to inelastically retune the warm cavities to decrease the unrestrained frequency by 200-300 kHz, this was done via the slow tuner. The results for this retuning method of three 3.9GHz cryomodules will be discussed.  
poster icon Poster SUPTEV014 [0.715 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV014  
About • Received ※ 22 June 2021 — Accepted ※ 23 January 2022 — Issue date; ※ 09 April 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV015 Mitigation of Dielectric Heating of Piezoelectric Actuators at Cryogenic Temperatures operation, SRF, linac, resonance 159
 
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • Y.M. Pischalnikov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  The new generation of low beam intensity superconducting linacs will require high accelerating gradients for new scientific discoveries. The high accelerating gradient cavities in pulsed SRF linacs will experience large (~1000’s of Hz) detuning caused by Lorentz force detuning (LFD). The piezo actuators that will be used to compensate large LFD must operate at a nominal voltage of 120V to 150V to deliver the required stroke to the cavity. In this high voltage range, the piezo is expected to warm up drastically due to its location in an insulating vacuum environment. Overheating of the piezo will significantly decrease the longevity of the actuator. A collaboration between FNAL and Physik Instrumente (PI) developed a novel piezo actuator design that mitigates piezo overheating. The design consists of using a metal foam in contact with the piezoelectric ceramic stack for heat removal. The second solution used lithium niobite as an alternative material. A comparison of the temperature stability will be presented and discussed. This study characterizes the dielectric properties for both materials. The results obtained are in the temperature range of 10 K to 300 K.  
poster icon Poster SUPTEV015 [0.728 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV015  
About • Received ※ 22 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 21 October 2021 — Issue date ※ 09 April 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV016 Samples for 3rd Harmonic Magnetometry Assessment of NbTiN-Based SIS Structures site, SRF, FEL, interface 164
 
  • D.R. Beverstock, J.R. Delayen, I.H. Senevirathne, J.K. Spradlin, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • J.R. Delayen, I.H. Senevirathne
    ODU, Norfolk, Virginia, USA
  • D. Manos
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. NSF Grants PHY-1734075 and PHY-1416051, and DOE Awards DE-SC0010081 and DE-SC0019399.
In the quest for alternative superconducting materials to bring accelerator cavity performance beyond the bulk niobium (Nb) intrinsic limits, a promising concept uses superconductor-insulator-superconductor (SIS) thin film structures that allows magnetic flux shielding in accelerator cavities to higher fields [1]. Candidate materials for such structures are NbTiN as the superconductor and AlN as the insulator. We have demonstrated high quality NbTiN and AlN deposited by reactive DC magnetron sputtering (DCMS), both for individual layers and multilayers. Interface quality has been assessed for bilayer stacks with 250 nm NbTiN layers and AlN thicknesses from 30 nm down to1 nm. These SIS structures show continued sharp interfaces with total average roughness under 2 nm. The Hfp enhancement of the films will be examined with a 3rd harmonic magnetometry. The system is being designed and built in a continuing collaboration with CEA Saclay. It can measure 25 to 50 mm samples on a temperature controlled stage. This contribution presents an overview of the design of the 3rd harmonic magnetometer and the material properties assessment of standalone films and multilayer nanostructures.
[1] A. Gurevich, Applied Physics Letters, vol. 88, p. 012511, 2006.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPTEV016  
About • Received ※ 22 June 2021 — Accepted ※ 10 November 2021 — Issue date; ※ 16 May 2022  
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MOOFAV01 Successful Beam Commissioning of Heavy-Ion Superconducting Linac at RIKEN linac, vacuum, acceleration, controls 167
 
  • K. Yamada, T. Dantsuka, M. Fujimaki, E. Ikezawa, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe
    RIKEN Nishina Center, Wako, Japan
  • H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, H. Nakai, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  A new superconducting booster linac, so-called SRILAC, has been constructed at the RIKEN Nishina Center to upgrade the acceleration voltage of the existing linac in order to enable further investigation of new super-heavy elements and the production of useful RIs. The SRILAC consists of 10 TEM quarter-wavelength resonators made from pure niobium sheets which operate at 4.5 K. We succeeded to develop high performance SC-cavities which satisfies the required Q0 of 1E+9 with a wide margin. Installation of the cryomodule and He refrigerator system was completed by the end of FY2018, and the first cooling test was performed in September 2019. After various tests of the RF system, the beam acceleration was successfully commissioned in January 2020. In June 2020, the beam supply to the experiment was started. In this talk, I will report on the beam commissioning of SRILAC as well as the status of the frequency tuner and the differential pump system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOOFAV01  
About • Received ※ 26 July 2021 — Revised ※ 30 August 2021 — Accepted ※ 05 March 2022 — Issue date ※ 16 May 2022
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MOOFAV02 Status of the RAON Superconducting Linear Accelerator cryomodule, MMI, linac, cryogenics 175
 
  • Y.U. Sohn, T.Y. Ki, Y. Kim, M. Lee, K.T. Seol
    IBS, Daejeon, Republic of Korea
 
  Funding: Ministry of Science and ICT (MSIT)
RAON, being constructed as the Rare Isotope Science Project (RISP) by the Institute for Basic Science (IBS) since 2011 is a flagship heavy ion accelerator facility in Korea to promote fundamental science and application of isotope nuclei and related science. The installation of the heavy ion accelerator systems including injector, rare isotope (RI) production systems, and experimental systems are currently being progressed toward to commissioning of RAON, while the civil construction of the RAON site in Shindong, Daejeon of Korea, is going to finish in 2021. The superconducting LINAC with low energy, so-call SCL3 as the 1st phase will be commissioned on the December of 2021. The overview RAON accelerator facility and status of RISP are reported in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOOFAV02  
About • Received ※ 26 August 2021 — Accepted ※ 05 April 2022 — Issue date; ※ 16 May 2022  
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MOOFAV05 Proton Improvement Plan ’ II: Overview of Progress in the Construction cryomodule, SRF, linac, operation 182
 
  • A.L. Klebaner, C. Boffo, S.K. Chandrasekaran, D. Passarelli, G. Wu
    Fermilab, Batavia, Illinois, USA
 
  Funding: US Department of Energy
The Proton Improvement Plan II (PIP-II) project is an essential upgrade to Fermilab’s particle accelerator complex to enable the world’s most intense neutrino beam for LBNF/DUNE and a broad particle physics program for many decades to come. PIP-II will deliver 1.2 MW of proton beam power from the Main Injector, upgradeable to multi-MW capability. The central element of PIP-II is an 800 MeV linac, which comprises a room temperature front end followed by an SRF accelerator. The front end has been constructed and operated with (pulsed & CW) beam in the PIP-II Injector Test facility (PIP2IT). The SRF accelerator consists of five different types of cavities/cryomodules, including Half Wave Resonators (HWR), Single Spoke and elliptical resonators operating at state-of-the-art parameters. The first two PIP-II cryomodules, HWR and Single Spoke Resonator 1 (SSR1) are installed in PIP2IT and have accelerated beam to 17 MeV. PIP-II is the first U.S. accelerator project that will be constructed with significant contributions from international partners, including India, Italy, France, United Kingdom and Poland. The project was recently baselined, and site construction is underway
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOOFAV05  
About • Received ※ 13 August 2021 — Revised ※ 14 January 2022 — Accepted ※ 21 February 2022 — Issue date ※ 13 March 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOOFAV06 Four Years of Successful Operation of the European XFEL operation, linac, FEL, controls 190
 
  • J. Branlard, S. Choroba, M.K. Grecki, S. Köpke, D. Kostin, D. Nölle, V. Vogel, N. Walker, S. Wiesenberg
    DESY, Hamburg, Germany
 
  The European X-Ray Free-Electron Laser (EuXFEL) has been successfully operating for almost 4 years, and routinely delivering 6- to 14-KeV X-rays to users (30 KeV photon energy was demonstrated). At the heart of the machine is the 1.3 km long 1.3 GHz SCRF linac which can reach a maximum electron energy of 17.6 GeV, and is capable of accelerating up to 2700 bunches per RF pulse at a repetition rate of 10 Hz, delivering beam to 6 experiments via 3 SASE undulator sections. In this contribution, we relate on the linac operational experience and highlight some recent developments towards monitoring and improving operations and linac availability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOOFAV06  
About • Received ※ 18 June 2021 — Accepted ※ 18 August 2021 — Issue date; ※ 18 September 2021  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOOFAV10 Completion of FRIB Superconducting Linac and Phased Beam Commissioning linac, cryomodule, MMI, SRF 197
 
  • T. Xu, Y. Al-Mahmoud, H. Ao, J. Asciutto, B. Bird, J. Bonofiglio, B. Bullock, N.K. Bultman, F. Casagrande, W. Chang, Y. Choi, C. Compton, J.C. Curtin, K.D. Davidson, K. Elliott, A. Facco, V. Ganni, A. Ganshyn, J. Gao, P.E. Gibson, Y. Hao, W. Hartung, N.M. Hasan, L. Hodges, K. Holland, J.D. Hulbert, M. Ikegami, T. Kanemura, S.H. Kim, P. Knudsen, Z. Li, S.M. Lidia, G. Machicoane, C. Magsig, P.E. Manwiller, F. Marti, T. Maruta, K.E. McGee, E.S. Metzgar, S.J. Miller, D.G. Morris, H. Nguyen, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, X. Rao, M.A. Reaume, H.T. Ren, K. Saito, M. Shuptar, A. Stolz, A. Taylor, B.P. Tousignant, A.D.F. Victory, D.R. Victory, J. Wei, E.M. Wellman, J.D. Wenstrom, Y. Yamazaki, C. Zhang, Q. Zhao, S. Zhao
    FRIB, East Lansing, Michigan, USA
  • K. Hosoyama
    KEK, Ibaraki, Japan
  • M.P. Kelly
    ANL, Lemont, Illinois, USA
  • R.E. Laxdal
    TRIUMF, Vancouver, Canada
  • M. Wiseman
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility for Rare Isotope Beams (FRIB) is an ac-celerator-based facility funded by the US Department of Energy for nuclear physics research. FRIB is nearing the end of technical construction, with first user beams ex-pected in Summer 2022. Key features are the delivery of a variety of rare isotopes with a beam energy of ’ 200 MeV/u and a beam power of up to 400 kW. The facility is upgradable to 400 MeV/u and multi-user capability. The FRIB driver linac consists of 324 superconducting resonators and 69 superconducting solenoids in 46 cry-omodules. FRIB is the first linac to deploy a large number of HWRs (220) and the first heavy ion linac to operate at 2 K. We report on the completion of production and in-stallation of the FRIB cryomodules and phased beam commissioning results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOOFAV10  
About • Received ※ 12 August 2021 — Revised ※ 16 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 04 May 2022
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MOPTEV002 Extended Range SRF Cavity Tuner for LCLS II HE Project cryomodule, SRF, operation, linac 203
 
  • Y.M. Pischalnikov, T.T. Arkan, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, T.N. Khabiboulline, Y.O. Orlov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
 
  Funding: This manuscript has been authorized by Fermi Research Alliance LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy.
The off-frequency detune method is being considered to be applied in the LCLS-II-HE superconducting linac to produce multi-energy electron beams for supporting multiple undulator lines simultaneously. To deliver off-frequency operation (OFO) requirements for SRF cavity tuner must be changed. Tuner design modifications and results of the testing eight cavity/tuner system, deployed in verification cryomodule (vCM), will be presented.
 
poster icon Poster MOPTEV002 [0.705 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV002  
About • Received ※ 22 June 2021 — Revised ※ 16 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 23 September 2021
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MOPTEV005 Commissioning of RF Power Coupler for BISOL R&D Research MMI, ISOL, SRF, vacuum 208
 
  • F. Zhu, S.W. Quan, Z.Q. Yao
    PKU, Beijing, People’s Republic of China
 
  RF power coupler is a key component of superconducting accelerating system. BISOL (Beijing isotope separation on line type rare ion beam facility) has two superconducting linear accelerators. Half wave resonators (HWRs) are adopted for the high intensity deuteron accelerator, and quarter wave resonators (QWRs) are used to accelerate heavy ions for the post acclerator. For the pre-research of BISOL, we designed a 162.5 MHz RF power coupler which can transmit CW 20 kW power for HWR cavities. It can also transmit 1-5 kW 81.25 MHz power for QWR cavity horizontal test study. A prototype of the coupler has been fabricated and proceeded the high power conditioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV005  
About • Received ※ 21 June 2021 — Revised ※ 29 September 2021 — Accepted ※ 17 January 2022 — Issue date ※ 21 February 2022
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MOPTEV006 Synchrotron XPS Study of Niobium Treated with Nitrogen Infusion niobium, vacuum, experiment, synchrotron 211
 
  • A.L. Prudnikava, J. Knobloch, O. Kugeler, Y. Tamashevich
    HZB, Berlin, Germany
  • V. Aristov, O. Molodtsova
    DESY, Hamburg, Germany
  • S. Babenkov
    LIDYL, Gif sur Yvette, France
  • A. Makarova
    FUB, Berlin, Germany
  • D. Smirnov
    Technische Universität Dresden, Dresden, Germany
 
  Processing of niobium cavities with the so-called ni-trogen infusion treatment demonstrates the improve-ment of efficiency and no degradation of maximal accelerating gradients. However, the chemical compo-sition of the niobium surface and especially the role of nitrogen gas in this treatment has been the topic of many debates. While our study of the infused niobium using synchrotron X-ray Photoelectron Spectroscopy (XPS) showed modification of the surface sub-oxides surprisingly there was no evidence of nitrogen con-centration build up during the 120°C baking step, irre-spectively of N2 supply. Noteworthy, that the niobium contamination with carbon and nitrogen took place during a prolonged high-temperature anneal even in a high vacuum condition (10-8-10-9 mbar). Evidently, the amount of such contamination appears to play a key role in the final cavity performance  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV006  
About • Received ※ 21 June 2021 — Revised ※ 13 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 05 September 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPTEV007 RF Conditioning of 120 kW CW 1.3 GHz High Power Couplers for the bERLinPro Energy Recovery Linac vacuum, SRF, booster, operation 216
 
  • A. Neumann, W. Anders, A. Frahm, F. Göbel, A. Heugel, S. Klauke, J. Knobloch, M. Schuster, Y. Tamashevich
    HZB, Berlin, Germany
 
  Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
This year, the commissioning of the 50 MeV, 100 mA bERLinPro Energy Recovery Linac test facility [1] will resume. For the Booster cryo-module of the injector line, operated with three modified 1.3 GHz Cornell style 2-cell SRF cavities, a new type of power coupler was developed, based on KEK’s C-ERL injector coupler. Modifications were made for a stronger coupling and lower emittance diluting coupler tip variant, a so-called "Golf Tee" shape and the cooling concept was redesigned based on KEK’s first experiences. For the final stage, the injector needs to deliver a low emittance beam of 100 mA average beam current at 6.5 MeV. That results in a traveling and continuous wave forward power requirement of up to 120 kW each of the twin setup feeding one Booster cavity. In this contribution we will give a short overview of the RF design and its impact on the beam’s emittance, give an overview of the conditioning teststand and the results achieved with the first pairs of couplers.
[1] M. Abo-Bakr et al., in Proc. 9th Int. Particle Accelerator Conf. (IPAC’18), Vancouver, BC, Canada, Apr. 4,, pp. 4127-4130, doi:10.18429/JACoW-IPAC2018-THPMF034
 
poster icon Poster MOPTEV007 [2.461 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV007  
About • Received ※ 19 June 2021 — Accepted ※ 19 August 2021 — Issue date; ※ 17 January 2022  
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MOPTEV009 A Method for In-Situ Q0 Measurements of High-Quality SRF Resonators beat-wave, SRF, resonance, experiment 221
 
  • S.V. Kuzikov, P.V. Avrakhov, C.-J. Jing, R.A. Kostin, Y. Zhao
    Euclid TechLabs, Solon, Ohio, USA
  • C.-J. Jing, C.-J. Jing
    ANL, Lemont, Illinois, USA
  • C.-J. Jing, R.A. Kostin
    Euclid Beamlabs, Bolingbrook, USA
  • R.A. Kostin, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • T. Powers, R.A. Rimmer
    JLab, Newport News, Virginia, USA
 
  Funding: The work was supported in the part by DoE SBIR grant #DE-SC0019687.
Accelerator projects such as LCLS-II naturally require low-loss superconducting (SRF) cavities. Due to strong demand for improving intrinsic quality factor (Q0), importance of accurate cavity characterization increases. We propose a method to measure Q0 in situ for an SRF resonator installed in its cryogenic module and connected with a RF feed source via a fixed RF coupler. The method exploits measurements of a response for an SRF resonator fed by an amplitude-modulated signal. Such a signal can be synthesized as a beat-wave composed of two frequencies that are close to the resonant frequency. Analyzing the envelope of the reflected signal, one can find the difference in reflection for the chosen frequencies and use them to compute the intrinsic Q. We also develop the methodology to carry out measurements of Q0 at the nominal cavity operating voltage. We verified our method in experiments with a room temperature copper resonator and with two SRF resonators including Fermilab’s 650 MHz cavity and JLab’s 1500 MHz cavity.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV009  
About • Received ※ 15 June 2021 — Revised ※ 26 August 2021 — Accepted ※ 19 February 2022 — Issue date ※ 06 April 2022
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MOPTEV010 RF System Experience for FRIB Half Wave Resonators controls, MMI, linac, detector 226
 
  • S. Zhao, W. Chang, E. Daykin, E. Gutierrez, S.H. Kim, S.R. Kunjir, T.L. Larter, D.G. Morris, J.T. Popielarski
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The installation and commissioning of the FRIB superconducting linac adopts a phased strategy. In SRF’19 we reported the progress on the commissioning of the linear segment 1 (LS1) which contains mainly the quarter wave resonators (QWRs). In this paper, we will report the recent progress on the commissioning of the remainder of the linac, including linear segment 2 (LS2), folding segment 2 (FS2) and linear segment 3 (LS3), focusing on the RF system experience for the half wave resonators (HWRs). Compared to the QWRs, the HWRs have a different type of tuner, run at higher power levels and have additional components (for example, high voltage bias tee for multipacting suppression and spark detector). Topics such as nonlinear tuner control for the pneumatic tuners; auto turn on/off implementation; and early issues and failures will be discussed in more detail.
 
poster icon Poster MOPTEV010 [1.599 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV010  
About • Received ※ 22 June 2021 — Revised ※ 22 August 2021 — Accepted ※ 16 November 2021 — Issue date ※ 22 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPTEV012 Extra-Cold EP Process at Fermilab controls, niobium, SRF, radio-frequency 230
 
  • F. Furuta, D.J. Bice, M. Martinello, T.J. Ring
    Fermilab, Batavia, Illinois, USA
 
  FNAL has established a cold Electro-Polishing (EP) method which maintains the outer surface temperature of cavity cell around 12~15°C during EP process. Cold EP has been applied on the various SRF cavities and contributed to achieve high RF performances with them. To investigate more feasibility and capability of EP at lower temperature, the FNAL EP temperature control tool was recently improved. Extra-cold EP process below 0°C at cavity cell region was successfully performed on 1.3 GHz 1-cell cavity. A compatible RF performance with cold EP method was also demonstrated during the cavity vertical testing. The details of extra-cold EP process and the cavity test results will be presented.  
poster icon Poster MOPTEV012 [2.034 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV012  
About • Received ※ 21 June 2021 — Accepted ※ 14 December 2021 — Issue date; ※ 16 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPTEV013 The VSR Demo Module Design – A Spaceframe-Based Module for Cavities with Warm Waveguide HOM Absorbers GUI, HOM, storage-ring, SRF 233
 
  • F. Glöckner, D. Böhlick, M. Bürger, V. Dürr, A. Frahm, J. Knobloch, F. Pflocksch, A.V. Vélez, D. Wolk, N.W. Wunderer
    HZB, Berlin, Germany
 
  The VSR (Variable pulse length Storage Ring) demo module is a prototype for the superconducting upgrade of HZB’s Bessy II. The module houses two 1.5 GHz superconducting cavities operated at 1.8 K in continuous wave (CW) mode. Each cavity has five water cooled Waveguide HOM Absorbers with high thermal load (450 W), which requires them to be water cooled. This setup introduces several design challenges, concerning space restriction, the interconnection of warm and cold parts and the alignment. In order to provide support and steady alignment an innovative space frame was designed. The transition from cold to warm over the partially superconducting waveguides made a more complex design for shielding and cooling system necessary. With the design close to completion, we are now entering the purchase phase.  
poster icon Poster MOPTEV013 [3.234 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV013  
About • Received ※ 21 June 2021 — Revised ※ 02 September 2021 — Accepted ※ 18 November 2021 — Issue date ※ 02 December 2021
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MOPTEV014 New Improved Horizontal Electropolishing System for SRF Cavities controls, cathode, operation, MMI 237
 
  • C.E. Reece, S. Castagnola, P. Denny, A.L.A. Mitchell
    JLab, Newport News, Virginia, USA
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OThR23177.
The best performance of niobium SRF accelerating cavities is obtained with surfaces smoothed with electropolishing chemical finishing. Jefferson Lab has recently specified, procured, installed, and commissioned a new versatile production electropolishing (EP) tool. Experience with EP research and operations at JLab as well as vendor interactions and experience guided development of the system specification. Detailed design and fabrication was awarded by contract to Semiconductor Process Equipment Corporation (SPEC). The delivered system was integrated into the JLab chemroom infrastructure and commissioned in 2020. The new EP tool provides much improved heat exchange from the circulating H2SO4/HF electrolyte and also the cavity via variable temperature external cooling water flow, resulting in quite uniform cavity wall temperature control and thus improved removal uniformity. With the JLab infrastructure, stabilized process temperature as low as 5 C is available. We describe the system and illustrate operational modes in this contribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV014  
About • Received ※ 21 June 2021 — Revised ※ 08 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 31 March 2022
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MOPTEV015 Spoke Tuner for the Minerva Project operation, linac, resonance, controls 241
 
  • N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
 
  In the framework of the MINERVA construction (MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility), a fully equipped prototype cryomodule is being developed. In order to control the resonance frequency of the cavities during operation, a deformation tuner has been studied. The kinematic model is based on a double lever system coupled with a screw nut linear actuator. The motion is generated by a stepper motor and two piezoelectric actuators working at low temperatures within the thermal insulation vacuum of the cryomodule. Key parameter of this work is the high tuning speed which is required to fulfill the fault tolerance strategy. This paper reports the design study and first tests of the built tuners at room temperature and in vertical cryostat configuration.  
poster icon Poster MOPTEV015 [3.179 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV015  
About • Received ※ 28 June 2021 — Revised ※ 15 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 01 April 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPTEV017 Development and Operation of PIP-II Injector Test, SSR1 Cryomodule, 325 MHz Amplifiers operation, rf-amplifier, radio-frequency, cryomodule 245
 
  • J. Steimel, V.M. Grzelak, D.W. Peterson
    Fermilab, Batavia, Illinois, USA
  • V.R. Bala, S.K. Bharade, G. Joshi, R. Keshwani, J.K. Mishra, M.M. Pande, S. Shrotriya, H. Shukla, S. Singh, C.I. Sujo
    BARC, Mumbai, India
  • D. Balakrishna, N. Chikte, S. Dubey, C. G, V. Gollapalli, J. K Chandra, V. Kumar, M. M, A. Maheshwari, S.N. Nagaratnam, G. Poornima, T.V.S. Thalluri
    ECIL, Hyderabad, India
 
  Funding: 1Fermilab, U.S.Department of Energy 2 Bhabha Atomic Research Centre, Department of Atomic Energy, Government of India 3 Electronic Corporation of India, Department of Atomic Energy, Government of India
The PIP-II Injector Test (PIP2IT) has successfully accelerated ionized hydrogen up to 17MeV through a superconducting, single spoke resonator (SSR1) cryomodule at Fermi National Accelerator Laboratory (FNAL). Each of the SSR1 cavities is tuned to 325MHz and requires up to 6 kW of RF power to accelerate 2mA of ionized hydrogen at the design gradients. RF power amplifiers, specialized for SRF cavity beam operations, were designed by Bhabha Atomic Research Center (BARC) and constructed in a collaboration between the BARC in Mumbai, India and the Electronics Corporation of India Limited (ECIL) in Hyderabad, India. The RF amplifiers meet the specifications and requirements mutually approved between BARC and FNAL. They operate at 325 MHz with a linear power output of 7 kW in both CW and pulse mode. The amplifiers are compatible with the FNAL accelerator personnel safety system and the cavity protection interlocks. Access to controls and internal diagnostic instrumentation are compatible with EPICS control standards. This paper gives details about RF power amplifier development within the Department of Atomic Energy (DAE), India and the operational details with PIP2IT at FNAL.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPTEV017  
About • Received ※ 28 June 2021 — Revised ※ 08 September 2021 — Accepted ※ 18 November 2021 — Issue date ※ 14 May 2022
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MOPCAV001 Cavity Production and Testing of the First C75 Cryomodule for CEBAF cryomodule, GUI, operation, HOM 250
 
  • G. Ciovati, G. Cheng, E. Daly, G.K. Davis, M.A. Drury, J.F. Fischer, D. Forehand, K. Macha, F. Marhauser, E.A. McEwen, A.L.A. Mitchell, A.V. Reilly, R.A. Rimmer, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The CEBAF cryomodule rework program was updated over the last few years to increase the energy gain of refurbished cryomodules to 75 MeV. The concept recycles the waveguide end-groups from original CEBAF cavities fabricated in the 1990s and replaces the five elliptical cells in each with a new optimized cell shape fabricated from large-grain, ingot Nb material. Eight cavities were fabricated at Research Instruments, Germany, and two cavities were built at Jefferson Lab. Each cavity was processed by electropolishing and tested at 2.07 K. The best eight cavities were assembled into ’cavity pairs’ and re-tested at 2.07 K, before assembly into the cryomodule. All but one cavity in the cryomodule were within 10% of the target accelerating gradient of 19 MV/m with a quality factor of 8·109. The performance limitations were field emission and multipacting.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV001  
About • Received ※ 17 June 2021 — Accepted ※ 21 February 2022 — Issue date; ※ 10 April 2022  
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MOPCAV002 Shape Evolution of C75 Large-Grain Niobium Half-Cells During Cavity Fabrication FEM, laser, software, cryomodule 255
 
  • G. Ciovati
    JLab, Newport News, Virginia, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The largely anisotropic deformation of large-grain Nb discs during deep drawing into half-cells poses a challenge for achieving a desired shape accuracy. Two 5-cell cavities for the C75 CEBAF cryomodule rework program have been fabricated at Jefferson Lab from large-grain Nb discs directly sliced from an ingot. The shape of the inner surface of eight half-cells has been inspected using a FARO Edge laser scanner during the fabrication process and compared to the reference shape. On average, approximately 63% of the half-cell inner surface was found to be within 0.1 mm of the reference shape and ~90% to be within 0.2 mm, after the final equator machining. Several 5-cell C75 cavities have also been fabricated at Research Instruments, Germany, and measurements of the shape accuracy using a Zeiss 3D coordinate measuring machine gave similar results. One half-cell was measured both at Research Instruments and Jefferson Lab for comparison.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV002  
About • Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 11 February 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPCAV004 Mechanical Properties of Directly Sliced Medium Grain Niobium for 1.3 GHz SRF Cavity niobium, SRF, cryogenics, collider 259
 
  • A. Kumar, K. Abe, T. Dohmae, S. Michizono, T. Saeki, Y. Watanabe, A. Yamamoto, M. Yamanaka
    KEK, Ibaraki, Japan
  • A. Fajardo, N. Lannoy
    ATI, Albany, Oregon, USA
  • G.R. Myneni
    JLab, Newport News, Virginia, USA
  • G.R. Myneni
    BSCE, Yorktown, Virginia, USA
 
  At KEK, research is being conducted to manufacture cost-effective 1.3 GHz superconducting radio frequency cavities based on the fine grain (FG) and large grain (LG) Niobium (Nb) materials. Medium grain (MG) Nb has been proposed and developed as an alternative to the FG and LG Nb, being expected to have better mechanical stability with a cost-effective and clean manufacturing approach. MG Nb has an average grain size of 200 - 300 µm, which is approximately 100 times smaller than the LG Nb, however, there are occasional grains as large as 1-2 mm. As such, it is expected to have isotropic properties rather than the anisotropic properties of LG Nb. In this paper, we will outline the mechanical properties of the directly sliced high RRR MG Nb material (manufactured by ATI), and a comparative study will be presented with respect to FG and LG Nb. Moreover, the viability of MG Nb for the global high-pressure regulation for 1.3 GHz SRF cavity will be presented.  
poster icon Poster MOPCAV004 [1.791 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV004  
About • Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 March 2022
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MOPCAV005 Status of SNS Proton Power Upgrade SRF Cavities Production Qualification cryomodule, proton, site, operation 265
 
  • P. Dhakal, E. Daly, G.K. Davis, J.F. Fischer, D. Forehand, N.A. Huque, A.L.A. Mitchell, P.D. Owen
    JLab, Newport News, Virginia, USA
  • M.P. Howell, S.-H. Kim, J.D. Mammosser
    ORNL, Oak Ridge, Tennessee, USA
 
  The Proton Power Upgrade project at Oak Ridge National Lab’s Spallation Neutron Source (SNS PPU) currently being constructed will double the proton beam power from 1.4 to 2.8 MW by adding 7 additional cryomodules, each contains four six-cell high beta (\beta = 0.81) superconducting radio frequency cavities. The cavities were built by Research Instruments, Germany, with all the cavity processing done at the vendor site, including electropolishing as the final active chemistry step. All 28 cavities needed for 7 cryomodules were delivered to Jefferson Lab, ready to be tested. The cryogenic RF qualifications and helium vessel welding were done at Jefferson Lab. The performance largely exceed the requirements, and greatly exceeded the performance of the original SNS cavity production series. Here, we present the summary of RF test on production cavities to this date.
This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
 
poster icon Poster MOPCAV005 [1.061 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV005  
About • Received ※ 19 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 12 March 2022 — Issue date ※ 06 April 2022
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MOPCAV006 High-Q/High-G R&D at KEK Using 9-Cell TESLA-Shaped Niobium Cavities SRF, niobium, vacuum, experiment 268
 
  • R. Katayama, A. Araki, H. Ito, E. Kako, T. Konomi, S. Michizono, M. Omet, K. Umemori
    KEK, Ibaraki, Japan
 
  We will report on the current progress of High-Q/High-G R&D using three 1.3 GHz 9-cell TESLA shape niobium superconducting cavities at the High Energy Accelerator Research Organization (KEK). These cavities are made of bulk niobium of fine grain material with RRR >300 and have been annealed at 900 degrees for 3 hours. The cavity performances were evaluated at the Superconducting RF Test Facility at KEK (KEK-STF) after 2-step bake (70-75°C 4 h + 120°C 48 h), electropolishing at low temperature, and fast cooling procedure were applied to these cavities. In this study, obtained results will be compared with the baseline measurement for the standard recipe at KEK.  
poster icon Poster MOPCAV006 [1.876 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV006  
About • Received ※ 22 June 2021 — Revised ※ 14 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 February 2022
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MOPCAV008 CiADS and HIAF Superconducting Cavity Development Status and the Transition to Production Stage linac, cryomodule, SRF, status 273
 
  • M. Xu, H. Guo, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, L.B. Liu, S.H. Liu, T. Liu, S.M. Shanab, T. Tan, Y. Tao, Y.Q. Wan, F.F. Wang, R.X. Wang, Z.J. Wang, P.R. Xiong, J.C. Yang, Z.Q. Yang, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
  • E.Z. Zaplatin
    FZJ, Jülich, Germany
 
  Funding: Work supported by Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 )
Two accelerators facilities, China initiative Accelerator Driven Sub-critical System (CiADS) and High Intensity heavy-ion Accelerator Facility (HIAF), co-funded by the China central and local government, is being designed and constructed at Huizhou city, Guangdong Province. The Institute of Modern Physics(IMP), Chinese Academy of Science is responded for constructing and operating the facility. CiADS’s mission is to demonstrate the principle and technical of employing high power protons to transit fission nuclear plant wastes. HIAF is defined as a nuclear structure research facility. The two linacs contains six types , totally 233 superconducting cavities, will be constructed in recent three years. Stable production rate and reliable surface processing will be the main challenges. This paper reports the cavity design, prototype status and massive production plan and status.
 
poster icon Poster MOPCAV008 [2.254 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV008  
About • Received ※ 22 June 2021 — Revised ※ 10 December 2021 — Accepted ※ 04 February 2022 — Issue date ※ 10 April 2022
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MOPCAV009 A New Process for Nitrogen Doping of Niobium Cavities niobium, SRF, superconductivity, controls 276
 
  • M. Cavellier
    Omega Physics, St Gildas de Rhuys, France
 
  Nitrogen-doping of Niobium cavities is now well known and industrialization of this process is emerging. However, the current process, based on thermal treatment in Nitrogen atmosphere leads to various inaccuracies (what is the concentration of Nitrogen in the Nb material? Penetration depth, created phases, …) and some post-treatment like chemical-mechanical polishing of the inner surface. This work presents a new and more accurate patented process based on nitrogen ion beam implantation into the inner surface of Nb cavities. Ion implantation is a well-known, controlled, accurate and reproducible process that does not require post-treatment. For these reasons, the industrialization of Nitrogen-doping Nb cavities will be improved through ion implantation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV009  
About • Received ※ 19 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 19 November 2021 — Issue date ※ 06 April 2022
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MOPCAV010 Design of a HOM-Damped 166.6 MHz Compact Quarter-Wave β=1 Superconducting Cavity for High Energy Photon Source HOM, superconducting-cavity, photon, niobium 278
 
  • X.Y. Zhang, J. Dai, L. Guo, T.M. Huang, Z.Q. Li, Q. Ma, F. Meng, Z.H. Mi, P. Zhang, H.J. Zheng
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
Superconducting cavities with low RF frequencies and heavy damping of higher order modes (HOM) are desired for the main accelerator of High Energy Photon Source (HEPS), a 6 GeV synchrotron light source promising ultralow emittance currently under construction in Beijing. A compact 166.6 MHz superconducting cavity was proposed adopting a quarter-wave β=1 geometry. Based on the successful development of a proof-of-principle cavity, a HOM-damped 166.6 MHz compact superconducting cavity was subsequently designed. Ferrite damper was installed on the beam pipe to reduce HOM impedance below stringent threshold of coupled-bunch instabilities. Being compact, RF field heating on the cavity vacuum seal was carefully examined against quenching the NbTi flange. The cavity was later dressed with helium vessel and the tuning mechanism was also realized. Excellent RF and mechanical properties were eventually achieved. Finally, the two-cavity string was designed to ensure smooth transitions among components and proper shielding of synchrotron light. This paper presents a complete design of a fully dressed HOM-damped low-frequency β=1 superconducting cavity for HEPS.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV010  
About • Received ※ 20 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 14 April 2022  
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MOPCAV011 Fabrication Process of Single Spoke Resonator Type-2 (SSR2) for RISP niobium, SRF, experiment, superconducting-cavity 283
 
  • M.O. Hyun, J. Joo, H.C. Jung, Y. Kim
    IBS, Daejeon, Republic of Korea
 
  Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea.
Rare Isotope Science Project (RISP) in the Institute of Basic Science (IBS), South Korea, is now constructing superconducting linear accelerator 3 (SCL3) for low-energy beam experiment and also making prototypes of superconducting cavity, RF power coupler, tuner, and cryomodule of superconducting (SC) linear accelerator 2 (SCL2) for high-energy beam experiment. Single spoke resonator type-1 (SSR1) and type-2 (SSR2) superconducting cavities are now on the prototyping stage. This paper explains about SSR2 fabrication process from press-forming to electron beam welding (EBW) with RRR300 niobium sheets.
 
poster icon Poster MOPCAV011 [1.949 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV011  
About • Received ※ 22 June 2021 — Revised ※ 26 August 2021 — Accepted ※ 26 August 2021 — Issue date ※ 22 April 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPCAV012 Fabrication of 1.3 GHz SRF Cavities Using Medium Grain Niobium Discs Directly Sliced from Forged Ingot niobium, SRF, cryogenics, superconductivity 287
 
  • T. Dohmae, K. Abe, H. Inoue, A. Kumar, S. Michizono, T. Saeki, K. Umemori, Y. Watanabe, A. Yamamoto, M. Yamanaka, K. Yoshida
    KEK, Ibaraki, Japan
  • A. Fajardo, N. Lannoy
    ATI, Albany, Oregon, USA
  • G.R. Myneni
    JLab, Newport News, USA
 
  Medium grain (MG) niobium disc which is directly sliced from forged ingot is newly investigated for the cavity material. An effective cost reduction can be achieved using MG niobium since rolling process which is necessary for typical niobium sheet can be skipped during MG niobium production. Grain size of MD niobium is 200-300 um which is much smaller than large grain (LG) niobium directly sliced from melted niobium ingot. Hence, the formability of MG niobium is expected to be much better than LG niobium. KEK has started fabrication of cavity using MG niobium. In this talk, characteristic of MG niobium during fabrication will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV012  
About • Received ※ 20 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 17 September 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPCAV013 LCLS-II-HE Vertical Acceptance Testing Plans multipactoring, cryomodule, HOM, accelerating-gradient 291
 
  • J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  LCLS-II-HE has performance requirements similar to but generally more demanding than those of LCLS-II, with an operating gradient of 21 MV/m (up from 16 MV/m in LCLS-II) and tighter restrictions on field emission and multipacting. In this paper, we outline the requirements for the 1.3 GHz cavities and the plans for qualification of these cavities by vertical test. We discuss lessons learned from LCLS-II and highlight the changes implemented in the vertical test procedure for the new project.  
poster icon Poster MOPCAV013 [0.413 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV013  
About • Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 02 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPCAV014 The Development of a Prototype Fundamental Power Coupler for CiADS and HIAF Half Wave Resonators operation, simulation, linac, coupling 295
 
  • T.C. Jiang, F. Bai, Y. He, Z.Q. Lin, Y.Q. Wan, R.X. Wang, Z.J. Wang, M. Xu, S.H. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  More than 100 Half-wave resonators (HWR) will be adopted for China Initiative Accelerator Driven Sys-tem (CiADS) and High Intensity heavy-ion Accelerator Facility (HIAF) at IMP. Each HWR cavity equips with one variable coupling, dual-warm-ceramic fundamen-tal power coupler (FPC). The FPC should be able to transmit up to 30 kW in CW mode. This paper will give an overview of the RF design of the 162.5 MHz CW power coupler. The coupler employs two warm ceram-ics in a 50 Ω coaxial line to ensure operation relia-bility. The results of thermal and thermomechanical will also be reported. Two prototype couplers have been fabricated and the RF measurements with low RF power were carried out.  
poster icon Poster MOPCAV014 [1.123 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV014  
About • Received ※ 21 June 2021 — Accepted ※ 01 April 2022 — Issue date; ※ 07 April 2022  
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MOPCAV015 Development of QWRS for the Future Upgrade of JAEA Tandem Superconducting Booster booster, acceleration, tandem-accelerator, operation 299
 
  • Y. Kondo, H. Kabumoto, M. Matsuda
    JAEA, Ibaraki-ken, Japan
  • T. Dohmae, E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • H. Harada, J. Kamiya, K. Moriya, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  The Japan Atomic Energy Agency (JAEA) tandem booster is one of the pioneering superconducting heavy ion linac in the world. It consists of 40 QWRs with an operation frequency of 130 MHz and βopt=0.1, and has potential to accelerate various ions up to Au to 10 MeV/u. The user operation was started in 1994, however, it has been suspended since the Great East Japan Earthquake in 2011. Recently, we started activities to investigate and improve the performance of the QWR cavities towards the restart of the tandem booster. In addition, design work of new lower beta cavities to improve the acceleration efficiency of heavier ions such as Uranium has been launched. Now we are surveying some operation frequencies and types of cavities including multi-gap QWR with use of electro-magnetic simulation of the cavities. In this work, the current status of the R&D program for the JAEA tandem facility is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV015  
About • Received ※ 20 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 01 October 2021  
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MOPCAV016 HOM Couplers and RF Antennas for HL-LHC Crab Cavities: Developments for Manufacturing HOM, niobium, SRF, operation 303
 
  • S. Barrière, S. Atieh, B. Bulat, R. Calaga, S.J. Calvo, O. Capatina, T. Demazière, G. Favre, A. Gallifa Terricabras, M. Garlasché, J.-M. Geisser, J.A. Mitchell, E. Montesinos, F. Motschmann, P. Naisson, R. Ninet, L. Prever-Loiri, L.R.A. Renaglia, K. Scibor, N. Villanti
    CERN, Geneva, Switzerland
 
  Superconducting RF crab cavities are being manufactured as part of the HL-LHC upgrade at CERN. Amongst its related ancillaries, radiofrequency HOM (High Order Modes) suppressors and field antennas are essential for reaching nominal performance during operation with high energy beams, as they monitor and control the electromagnetic fields in the cavities. Several concepts of such equipment have been engineered and manufactured, for both design validation and RF performance assessment. The following paper highlights manufacturing process definition, its challenges and the assembly strategies focusing on the ongoing RFD prototypes for the SPS beam tests. Specific tooling development and test campaigns are also described.  
poster icon Poster MOPCAV016 [1.452 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV016  
About • Received ※ 21 June 2021 — Revised ※ 10 July 2021 — Accepted ※ 11 November 2021 — Issue date ※ 18 November 2021
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MOPFAV002 Commissioning of the UKRI STFC Daresbury Vertical Test Facility for Jacketed SRF Cavities SRF, cryogenics, MMI, operation 308
 
  • A.J. May, A.A. Akintola, A.R. Bainbridge, R.K. Buckley, G. Collier, P.A. Corlett, K.D. Dumbell, M.J. Ellis, S. Hitchen, P.C. Hornickel, G. Hughes, C.R. Jenkins, P.A. McIntosh, K.J. Middleman, A.J. Moss, N. Pattalwar, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse, AAJ. White, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • M.D. Hancock, J. Hathaway, C. Hodgkinson, G. Jones, M. Lowe, D.A. Mason, G. Miller, J. Mutch, A. Oates, P. Sollars, J.T.G. Wilson
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  A novel vertical test facility has been developed at the STFC Daresbury Laboratory. The VTF is designed to test 3 jacketed SRF cavities in a horizontal configuration in a single cool-down run at 2 K. Cavities were tested at low power levels for HOMs and passband modes, and Q vs E field measurements at high power levels. The specification requires an unloaded Q of 5·109 at a field gradient of 19.9 MV/m. The cavities are cooled with superfluid helium filled into their individual helium jackets. This reduces the liquid helium consumption by more than 70% in comparison with the conventional facilities operational elsewhere. The facility will be used to conduct a 2-year program to qualify 84 high-beta SRF cavities for the European Spallation Source as part of the UK’s in-kind contribution. This paper reports on the commissioning program, along with a detailed discussion of the RF and cryogenic operations and performance of the facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFAV002  
About • Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 20 October 2021
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MOPFAV004 First Vertical Test of a Prototype Crab Cavity for HL-LHC at FREIA Laboratory in Uppsala University experiment, SRF, MMI, dipole 313
 
  • A. Miyazaki, K. Fransson, K.J. Gajewski, L. Hermansson, R.J.M.Y. Ruber
    Uppsala University, Uppsala, Sweden
 
  We developed and commissioned a new vertical test stand at FREIA Laboratory for the High-Lumi LHC project. The first cold test was performed with a prototype crab cavity (Double-Quarter-Wave cavity) and the obtained result met the project specification. This opened a new opportunity at Uppsala University for SRF science and engineering. In this poster, the result of the first cold test and plans for future experiments are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFAV004  
About • Received ※ 21 June 2021 — Revised ※ 14 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 07 October 2021
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MOPFAV005 Operation Experience of the Superconducting Linac at RIKEN RIBF radiation, operation, linac, vacuum 315
 
  • N. Sakamoto, O. Kamigaito, T. Nagatomo, T. Nishi, K. Ozeki, K. Suda, A. Uchiyama, K. Yamada
    RIKEN Nishina Center, Wako, Japan
 
  After commissioning of the RIKEN superconducting linac (SRILAC) in the end of FY2019, heavy ion beams were provided to the nuclear physics experiments. In this paper operation history and evolution of field emission levels through the year will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFAV005  
About • Received ※ 02 July 2021 — Accepted ※ 27 October 2021 — Issue date; ※ 10 April 2022  
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MOPFDV001 Investigation of an Alternative Path for SRF Cavity Fabrication and Surface Processing SRF, niobium, embedded, laser 319
 
  • O. Hryhorenko, D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • F. Brisset
    ICMMO, Orsay, France
  • T. Dohmae
    KEK, Ibaraki, Japan
 
  The preparation of SRF cavities includes a lengthy, costly, and safety issued electrochemical polishing (EP or BCP) step to remove the damaged layer coming from the cavity fabrication. We have shown that most of the damage layer is originated from the rolling process during the preparation of the sheet material, while subsequent deep drawing tends to leave only µm thick damage layer. We propose a 2-steps mechanical process that allows us to easily get rid of the thick damage layer on the sheets before cavity forming. The process has been established on samples and extended to large disks ready for 1.3 GHz half-cell forming. The polished sheets will be then sent to KEK for half-cell forming and subsequent surface and material analysis before proceeding to half-cell welding. Former studies on the sample demonstrated that damages induced by forming can successfully be removed by recrystallization and less than 10 µm final chemistry.  
poster icon Poster MOPFDV001 [2.303 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV001  
About • Received ※ 25 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 15 May 2022
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MOPFDV002 High Density Mapping Sytems for SRF Cavities SRF, cryogenics, experiment, superconducting-cavity 323
 
  • Y. Fuwa
    JAEA/J-PARC, Tokai-mura, Japan
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  • Y. Iwashita, Y. Kuriyama
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
 
  High density mapping systems for superconducting cavities are prepared. They include sX-map, XT-map and B-map. Each strip of the sX-map system has 32 X-ray sensors approximately 10 mm apart, which can be installed under the stiffener rings to show uniform higher sensitivities. This is suitable to get X-ray distribution around iris areas. The XT-map system enables temperature distribution mapping of cavity cells with high spatial resolution at approximately 10 mm intervals in both azimuth and latitude. It also gives X-ray distribution on cells, as well. Magnetic field distributions can be obtained by B-map system using AMR sensors. Since all these systems are based on the technology of multiplexing at cryogenic side, less number of wires can carry the huge number of signals. The systems are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV002  
About • Received ※ 02 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 22 January 2022 — Issue date ※ 02 May 2022
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MOPFDV003 Measuring Flux Trapping Using Flat Samples simulation, experiment, controls, HOM 326
 
  • F. Kramer, S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
 
  With modern superconducting cavities flux trapping is a limiting factor for the achievable quality factor. Flux trapping is influenced by various parameters such as geometry, material, and cooldown dynamics. At SRF2019 we presented data showing the magnetic field surrounding a cavity. We now present supplemental simulations for this data focusing on geometric effects. As these simulations are inconclusive, we have designed a new setup to measure trapped flux in superconducting samples which is presented as well. The advantages compared to a cavity test are the simpler sample geometry, and quicker sample production, as well as shorter measurement times. With this setup we hope to identify fundamental mechanisms of flux trapping, including geometry effects, different materials, and different treatments. First results are presented along with the setup itself.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV003  
About • Received ※ 21 June 2021 — Accepted ※ 03 April 2022 — Issue date; ※ 02 May 2022  
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MOPFDV008 SRF Levitation and Trapping of Nanoparticles SRF, experiment, vacuum, niobium 331
 
  • R.L. Geng
    ORNL, Oak Ridge, Tennessee, USA
  • P. Dhakal, B.J. Kross, F. Marhauser, J.E. McKisson, J. Musson, H. Wang, A. Weisenberger, W.Z. Xi
    JLab, Newport News, Virginia, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences & Office of Nuclear Physics.
A proposal has been conceived to levitate and trap mesoscopic particles using radio frequency (RF) fields in a superconducting RF(SRF) cavity. Exploiting the intrinsic characteristics of an SRF cavity, this proposal aims at overcoming a major limit faced by state-of-the-art laser trapping techniques. The goal of the proposal is to establish a foundation to enable observation of quantum phenomena of an isolated mechanical oscillator interacting with microwave fields. An experiment supported by LDRD funding at JLab has started to address R&D issues relevant to these new research directions using existing SRF facilities at JLab. The success of this experiment would establish its groundbreaking relevance to quantum information science and technology, which may lead to applications in precision force measurement sensors, quantum memories, and alternative quantum computing implementations with promises for superior coherence characteristics and scalability well beyond the start-of-the-art. In this contribution, we will introduce the proposal and basic consideration of the experiment.
 
poster icon Poster MOPFDV008 [0.595 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV008  
About • Received ※ 10 June 2021 — Accepted ※ 30 September 2021 — Issue date; ※ 02 May 2022  
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MOPFDV009 On the Nature of Surface Defects Found in 2/0 N-Doped 9-Cell Cavities SRF, survey, electron, superconductivity 336
 
  • A. Cano, D. Bafia, A. Grassellino, J. Lee, M. Martinello, A.S. Romanenko, T. Spina, Z-H. Sung
    Fermilab, Batavia, Illinois, USA
 
  In this contribution, we present a systematic study on the microstructure of 1.3 GHz 9-cell TESLA type SRF cavity, processed with 2/0 Nitrogen-doping surface treatment, to explain the premature quench phenomena commonly observed in N-doping treated cavities. The microstructure characterization was carried out using Secondary electron images, advanced metallurgical techniques such as EBSD in parallel with chemical information obtained from spectroscopic techniques. The most remarkable difference is observed in the ends-cavities (1 and 9), which showed roughening of the surface, revealing a series of morphologies associated with Nb cubic phase. The cell-to-cell analysis also showed standard features such as pits with different geometry and distribution, located in grains and grain boundaries. The defects found in this system suggest that the standard electropolishing chemical etching was insufficient to eliminate history defects produced during the manufacture of the cavity, without discarding the role of the impurities, N and O, that could have induced the growth of these morphologies.
H. Padamsee, RF superconductivity (Wiley-VCH Verlag GmbH and Co., KGaA, Weinheim, 2009)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV009  
About • Received ※ 29 June 2021 — Revised ※ 11 March 2022 — Accepted ※ 10 May 2022 — Issue date ※ 11 May 2022
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MOPFDV010 MICROSTRUCTURE CHANGES OBSERVED IN THE NEAR-SURFACE REGION OF SRF Nb CAVITIES CUTOUTS UPON COOLING/HEATING CYCLES USING GI-SYNCHROTRON XRD site, SRF, lattice, niobium 339
 
  • A. Cano, D. Bafia, A. Grassellino, J. Lee, M. Martinello, A.S. Romanenko, T. Spina, Z-H. Sung
    Fermilab, Batavia, Illinois, USA
  • E.A. Karapetrova
    ANL, Lemont, Illinois, USA
 
  We have mapped microstructural changes in the near-surface region of Nb from SRF cavity-cutouts upon thermal cycles in the range from 300 to 30K using grazing incidence synchrotron X-ray diffraction (GIXRD). Segregation of secondary phases was observed after the thermal cycle, and their nature has been clarified and discussed in view of previous studies on hydrides formation in SRF bulk Nb cavities. The temperature dependence of the relative population of these formed phases was obtained from GIXRD patterns profile fitting. Both, Nb bulk matrix and the new phases formed after cool-down show specific structural features as thermal contraction/expansion, structural transitions, and Nb lattice variation due to the induced strain by precipitates formation. The information derived from this structural study can explain some phenomena as the dissipation at high accelerating field (i.e. High Field Q Slope, HFQS) in the Nb SRF performance as well as new mechanisms never addressed in previous studies.
A Romanenko, F Barkov, LD Cooley, A Grassellino, Proximity breakdown of hydrides in superconducting niobium cavities, Superconductor Science and Technology, 2013
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPFDV010  
About • Received ※ 28 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 23 September 2021
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TUOFDV03 Vacancy-Hydrogen Dynamics and Magnetic Impurities During Mid-T Bake niobium, lattice, interface, positron 342
 
  • M. Wenskat, C. Bate, D. Reschke, J. Schaffran, L. Steder, H. Weise
    DESY, Hamburg, Germany
  • C. Bate, G.D.L. Semione, A. Stierle
    University of Hamburg, Hamburg, Germany
  • M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner
    HZDR, Dresden, Germany
  • J. Cizek
    Charles University, Prague, Czech Republic
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Positron annihilation measurements allow to study the hydrogen interaction with vacancies in a crystal lattice. Furthermore, the 3/2 ratio of the positronium annihilation can be used to identify local magnetic impurities in thin layers. Dynamic studies of these properties in annealing studies up to 300°C will be presented. The discussion is accompanied by X-ray reflectivity studies performed on single crystal samples to study the niobium oxide dissolution. The dynamics of magnetic impurities during a Mid-T bake will be presented, put into the context of cavity studies and a potential link to rf properties will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUOFDV03  
About • Received ※ 23 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 05 December 2021
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TUOFDV05 Dynamics of RF Dissipation Probed via High-Speed Temperature Mapping SRF, site, electron, data-acquisition 349
 
  • R.D. Porter, N. Banerjee, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Recently, Cornell University has developed a new high-speed, high-resolution temperature mapping system that can resolve the time dynamics of RF dissipation, i.e., provide high-speed videos of the surface heating across the entire surface of the cavity. This new powerful tool allows to observe rapid changes in the local RF dissipation, as well as to resolve the dynamics of quenches, field emission processing, and other cavity events, giving new insights into these. This contribution presents the development of this new high-speed temperature mapping system, discusses its commissioning and extensive performance testing (e.g., demonstrating micro-Kelvin resolution), as well as show intriguing high-speed temperature mapping results from multiple Nb3Sn cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUOFDV05  
About • Received ※ 01 July 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 06 February 2022  
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TUOFDV07 Sample Test Systems for Next-Gen SRF Surfaces SRF, niobium, quadrupole, operation 357
 
  • T.E. Oseroff, M. Liepe, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  With the increasing worldwide focus on the development of new surfaces for SRF cavities, exploring alternative materials and multilayer structures, test systems that allow measuring the RF performance of simple sample geometries (e.g., flat samples) become increasingly essential. These systems provide RF performance results that are needed to guide the development of these surfaces. This contribution gives an overview of sample test systems currently available, including the improved Cornell sample host cavity. Recent advances in this important technology, performance specifications, and current limitations are discussed. In addition, an overview is given of interesting recent RF performance results on samples coated with non-niobium bulk and multilayer films.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUOFDV07  
About • Received ※ 08 July 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 05 September 2021  
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TUOFDV08 First Beta NMR Results on SRF Samples at TRIUMF SRF, polarization, niobium, ISAC 365
 
  • E. Thoeng, J.R. Adelman, A. Chatzichristos, M. Dehn, D. Fujimoto, V.L. Karner, R. Kiefl, W.A. MacFarlane, J.O. Ticknor
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • M. Asaduzzaman, T. Junginger
    UVIC, Victoria, Canada
  • R.A. Baartman, S.R. Dunsiger, T. Junginger, P. Kolb, R.E. Laxdal, C.D.P. Levy, Li,R. Li, R.M.L. McFadden, I. McKenzie, G. Morris, S. Saminathan, M. Stachura
    TRIUMF, Vancouver, Canada
  • D.L. Cortie
    University of Wollongong, Institute of Superconducting and Electronic Materials, Wollongong, New South Wales, Australia
 
  The \betaNMR (\beta-detected nuclear magnetic resonance) facility at TRIUMF offers the possibility of depth-resolved probing of the Meissner state over the first §I{100}{\nano\meter} below a sample surface. The measurement can give the attenuation of the applied magnetic field, as a function of depth. The technique can be especially important when probing layered systems like the dirty/clean S-S (superconductor-superconductor) bi-layer and S-I-S (Superconductor-Insulator-Superconductor) structures. The TRIUMF SRF (Superconducting RF) group has recently completed first measurements at beta-NMR on Nb samples with various treatments. The results and method will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUOFDV08  
About • Received ※ 09 July 2021 — Revised ※ 29 September 2021 — Accepted ※ 07 May 2022 — Issue date ※ 08 May 2022
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TUPFAV001 Progress on SRF Linac Development for the Accelerator-Driven Subcritical System at JAEA linac, SRF, operation, optics 372
 
  • B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  To overcome the nuclear waste problem, the Japan Atomic Energy Agency (JAEA) has been developing an accelerator-driven subcritical system (ADS) since the late 1980s. In the JAEA-ADS proposal, an 800 MWth subcritical reactor is driven by a 30 MW cw proton linear accelerator (linac). The biggest challenges for the ADS machines are the high reliability and availability required for their operations. To this end, the present JAEA-ADS linac was redesigned by adopting the current developments in Superconducting Radio-Frequency (SRF) technology. Additionally, we developed a robust lattice to control the beam loss and implemented a fault-tolerance scheme for the fast recovery of SRF cavity failures. This work presents the latest results of the R&D of the JAEA-ADS superconducting linac.  
poster icon Poster TUPFAV001 [0.708 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV001  
About • Received ※ 07 June 2021 — Revised ※ 14 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 26 November 2021
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TUPFAV002 Calibration of SRF Cavity Voltage by Measurement of Synchrotron Frequency in SuperKEKB factory, operation, SRF, pick-up 376
 
  • M. Nishiwaki, K. Akai, T. Furuya, T. Kobayashi, S. Mitsunobu, Y. Morita, T. Okada
    KEK, Ibaraki, Japan
 
  Eight SRF cavity modules, which have been operated in KEKB for more than ten years, are stably operating also in SuperKEKB. As for calibration of the cavity voltage Vc, non-negligible discrepancy was observed between the results obtained from two different methods: one is using external Q value (Qext) of pickup ports, and the other is using loaded Q value (QL) of the cavities. The discrepancy comes from inaccuracy of power measurement in high power RF system and uncertainty of the Qext or QL values. In order to solve the discrepancy by improving the accuracy of the calibration for each individual cavity, we investigated a method by measuring synchrotron frequency fs of stored beam. With this method, Vc calibration can be performed without affected by inaccuracy of high-power measurement or uncertainty of the Qext or QL values. The fs measurement studies were carried out in SuperKEKB. With these studies, Vc calibration was obtained with a high accuracy of about 1%. The results are applied to the SuperKEKB operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV002  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 October 2021
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TUPFAV003 Stable Beam Operation at 33 MV/m in STF-2 Cryomodules at KEK operation, accelerating-gradient, cryomodule, radiation 382
 
  • Y. Yamamoto, M. Akemoto, D.A. Arakawa, A. Araki, S. Araki, A. Aryshev, T. Dohmae, M. Egi, M.K. Fukuda, K. Hara, H. Hayano, Y. Honda, T. Honma, H. Ito, E. Kako, H. Katagiri, R. Katayama, M. Kawamura, N. Kimura, Y. Kojima, Y. Kondou, T. Konomi, M. Masuzawa, T. Matsumoto, S. Michizono, Y. Morikawa, H. Nakai, H. Nakajima, K. Nakanishi, M. Omet, T. Oyama, T. Saeki, H. Sakai, H. Shimizu, S.I. Takahara, R. Ueki, K. Umemori, A. Yamamoto
    KEK, Ibaraki, Japan
  • S. Aramoto
    Hiroshima University, Higashi-Hiroshima, Japan
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  • Z.J. Liptak
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Sakaue
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  • A. Yamamoto
    CERN, Meyrin, Switzerland
 
  In STF at KEK, as the operational demonstration of the SRF accelerator for ILC, the STF-2 cryomodules (CM1+CM2a: one and half size CM with 12 cavities) have achieved 33 MV/m as average accelerating gradient with 7 cavities in Mar/2019. After that, one cavity with the lowest performance installed in CM2a was replaced with one N-infused cavity developed for High-Q/High-G R&D between Japan and US. From this April, the beam operation started again and those CMs achieved 33 MV/m as average accelerating gradient with 9 cavities including one N-infused cavity again. This is the very important milestone for ILC. In this report, the detailed results will be presented.  
poster icon Poster TUPFAV003 [3.015 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV003  
About • Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 01 November 2021
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TUPFAV004 Surface Polishing Facility for Superconducting RF Cavities at CERN controls, interface, PLC, niobium 387
 
  • L.M.A. Ferreira, N.S. Chritin, R. Ferreira, G. Gerbet
    CERN, Geneva, Switzerland
 
  A new SRF cavity polishing facility which covers the needs for present projects like the HL-LHC and its CRAB cavities as well as ongoing and future activities in the frame of the FCC study was commissioned at CERN in 2019. This facility can handle chemical and electrochemical polishing baths, can process both niobium and copper-based cavities on a wide range of geometries, starting at 400 MHz up to 1.3 GHz for elliptical type of cavities and more complex shapes as defined by the DQW and RFD CRAB design. The main subassemblies of this facility are presented. Some important design details and materials choices of the facility will be briefly discussed together with the range of operational parameters. First results on different substrates and geometries are discussed in terms of surface finishing and polishing rate uniformity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV004  
About • Received ※ 17 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 25 October 2021
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TUPFAV006 The Superconducting Radio Frequency System of Shenzhen Industrial Synchrotron Radiation Source FacilityRIAL SYNCHROTRON RADIATION SOURCE FACILITY radiation, synchrotron, storage-ring, radio-frequency 392
 
  • W. Ma, Y.B. Sun, N. Yuan
    Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
  • L.G. Liu
    SSRF, Shanghai, People’s Republic of China
  • L. Lu, L. Yang, Z.L. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Shenzhen industrial synchrotron radiation source is a 3 GeV synchrotron radiation diffraction-limited source. It consists of three parts, linear accelerator, booster, and storage ring. As a basic part of the storage ring, the superconducting radio frequency system provides energy for the beam to supplement the beam power loss caused by synchrotron radiation and higher-order modes, and provide the longitudinal bunch for the electron beam. The superconducting radio frequency cavity of the storage ring consists of two 500 MHz single-cell cavities and a third harmonic 1500 MHz double-cell cavity. This paper will introduce the superconducting cavity, radio frequency amplifier, and low-level radio frequency system in the Shenzhen industrial synchrotron radiation source facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFAV006  
About • Received ※ 20 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 26 November 2021
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TUPFDV001 Effect of Heating Rate on Recrystallization in Rolled Multicrystals of Pure Niobium ECR, niobium, SRF, superconductivity 396
 
  • T.R. Bieler, D. Kang
    Michigan State University, East Lansing, Michigan, USA
  • R.R. Desconocido, M.T. Sanchez
    UPM, Madrid, Spain
  • N. Fleming, C. McKinney, Z.L. Thune, K. Zheng
    MSU, East Lansing, USA
  • A.A. Kolka
    Niowave, Inc., Lansing, Michigan, USA
 
  Funding: Supported by US Dept. of Energy award DE-SC0009960.
The performance of niobium cavities in superconducting radiofrequency particle accelerators requires nearly defect-free inner surfaces. While methods to obtain smooth inner surfaces are established, the role of metallurgical defects on superconducting performance is also important, as defects such as grain boundaries and dislocations are known to trap flux that dissipates energy and reduces efficiency. Variable microstructure and texture gradients may account for the observed variability in cavity performance, so it is hypothesized that the texture and microstructure gradients originate from the large grain size of ingots, whose influence is not completely erased in the process of making sheet metal. To examine the evolution of microstructure and texture gradients, the crystal orientations present in a cylindrical cap rolled to ~90% reduction were heat treated. Initial crystal orientations were measured before rolling, and before and after slow and rapid heating rate vacuum heat treatments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV001  
About • Received ※ 23 June 2021 — Revised ※ 22 February 2022 — Accepted ※ 04 May 2022 — Issue date ※ 16 May 2022
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TUPFDV002 SIMS Sample Holder and Grain Orientation Effects niobium, SRF, experiment, simulation 401
 
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • M.J. Kelley, E.M. Lechner, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • F.A. Stevie
    NCSU AIF, Raleigh, North Carolina, USA
 
  SIMS analyses for ’N-doped’ materials are becoming increasingly important. A major hurdle to acquiring quantitative SIMS results for these materials is the uncertainty of instrument calibration due to changes in sample height either from sample topography or from the sample holder itself. The CAMECA sample holder design allows for many types of samples to be analyzed. However, the cost is that the holder faceplate can bend, introducing uncertainty into the SIMS results. Here we designed and created an improved sample holder which is reinforced to prevent faceplate deflection and thereby reduce uncertainty. Simulations show that the new design significantly reduces deflection from 10 µm to 5 nm. Measurements show a reduction of calibration (RSF) uncertainty from this source from 4.1% to 0.95%. Grain orientation has long been suspected to affect RSF determination as well. A bicrystal implant standard consisting of [111] and [001] grains were repeatedly rotated 15° in between analyses. It was observed that 20% of the analyses performed on [111] grains exhibited anomalously high RSF values likely due to the changing of the grain normal with respect to the primary Cs+ beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV002  
About • Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 05 January 2022
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TUPFDV004 A SIMS Approach for the Analysis of Furnace Contamination niobium, SRF, survey, electron 406
 
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • M.J. Kelley, E.M. Lechner, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • F.A. Stevie
    NCSU AIF, Raleigh, North Carolina, USA
 
  Detection of surface contamination for SRF material is difficult due to the miniscule quantities and near atomic resolution needed. Visual inspection of samples known to have experienced surface contamination were found to have inconsistent nitride coverage after nitrogen doping. EBSD analysis suggest that nitride suppression tends to be most prevalent when deviating from the [111] and [001] zone axes. XPS suggested that tin was present as a contaminant on the surface with SIMS mass spectra also confirming its presence. SIMS depth profiles show a depletion of nitrogen content as well as an increase in car-bon content for contaminated samples.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV004  
About • Received ※ 22 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 19 February 2022
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TUPFDV007 Surface Impedance of Nb3Sn and YBa2Cu3O7-δ in High Magnetic Fields impedance, radio-frequency, framework, electron 416
 
  • N. Pompeo, A. Alimenti, E. Silva, K. Torokhtii
    Università degli Studi Roma III, Roma, Italy
  • G. Celentano, V. Pinto, F. Rizzo
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • R. Flükiger
    UNIGE, Geneva, Switzerland
  • T. Spina
    Fermilab, Batavia, Illinois, USA
 
  Funding: This work has been partially carried out within the framework of the EUROfusion consortium, funding from the Euratom research and training programme 2014-18 and 2019-20 under grant agreement No 633053
New potential rf applications of superconductors emerged with the need to operate in high dc magnetic fields (up to 16 T) where vortex motion dictates the response: the beam screen coating of the Future Circular Collider (FCC) [1] and haloscopes, i.e. rf cavities for the axions detection [2]. However, very few data are available in the required regimes. We present in this work measurements of the surface impedance Z up to 12 T on bulk Nb3Sn and YBCO thin films grown by different techniques. The measurements are performed with a dielectric loaded resonator operating at 15 GHz. We obtained the vortex motion resistivity and extracted the high frequency vortex motion parameters [3]: the depinning frequency, the flux-flow resistivity and the pinning constant, as well as their temperature and field dependences. Substantial differences are highlighted in the high frequency pinning properties of the studied materials, providing useful information on possible improvements in view of applications. A comparison with the results obtained in the microwave frequency range at lower fields (up to 1 T) is given.
[1] S. Calatroni, IEEE Trans. Appl. Supercond., vol. 26 p. 3500204, 2016.
[2] D. Alesini et al., Phys. Rev. D, vol. 99, p. 101101, 2019.
[3] J.I. Gittleman and B. Rosenblum, Phys. Rev. Lett., vol. 16, p.734, 1966.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV007  
About • Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 02 January 2022  
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TUPFDV008 Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University SRF, experiment, superconductivity, controls 421
 
  • Y. Fuwa
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Hayano, H. Ito, R. Katayama, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • Y. Iwashita, Y. Kuriyama
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
 
  We have been developing SRF instrumentations by which the effective lower critical magnetic field Hc1,eff of superconducting-material sample is evaluated through the method of the third-order harmonic voltage measurement mainly for the studies of new SRF thin-film structures. Recently, the quad coil system, which enables us to measure four samples simultaneously in a single batch of an experiment, has been developed. In order to study the creation of thin-film structures inside the SRF cavity, we developed 3-GHz-shaped coupon cavities and an XT-map system for the performance tests of 3 GHz cavities. This article reports the details of these works.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV008  
About • Received ※ 01 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 02 April 2022 — Issue date ※ 02 May 2022
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TUPFDV010 New Recipes to Optimize the Niobium Oxide Surface From First-Principles Calculations niobium, electron, SRF, site 426
 
  • N. Sitaraman, T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller
    Cornell University, Ithaca, New York, USA
  • M. Liepe, R.D. Porter, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams
The properties of niobium oxide are of critical importance for a wide range of topics, from the behavior of nitrogen during infusion treatments, to the nucleation of Nb3Sn, to the superconducting properties of the surface. However, the modeling of the oxide is often much simplified, ignoring the variety of niobium oxide phases and the extremely different properties of these phases in the presence of impurities and defects. We use density functional theory (DFT) to investigate how electrochemical treatments and gas infusion procedures change the properties of niobium oxide, and to investigate how these properties could be optimized for Nb3Sn nucleation and for niobium SRF performance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPFDV010  
About • Received ※ 01 July 2021 — Accepted ※ 18 November 2021 — Issue date; ※ 22 February 2022  
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TUPCAV001 Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: First Results cathode, niobium, experiment, linac 431
 
  • F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin
    CEA-DRF-IRFU, France
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki
    KEK, Ibaraki, Japan
  • G. Jullien
    CEA-IRFU, Gif-sur-Yvette, France
 
  Vertical Electro-Polishing (VEP) of elliptical cavities using rotating Ninja cathodes (Marui Company patented technology) has continually been improved since 2012 and successfully applied for 1300MHz multicell ILC-type resonators. The goal of the presented study is to apply this technology to 704 MHz ESS-type resonators with both better Q0 and accelerating gradients in mind. We intend to demonstrate the superiority of VEP compared to standard Buffer Chemical Polishing (BCP), for possible applications such as MYRRHA accelerator. We describe here the promising results achieved on β=0.86 single-cell cavity after 200 µm uniform removal. The cavity quenched at 27 MV/m without any heat treatment. The surface resistance achieved was less than 5nΩ at 1.8K. Substantial performance improvement is expected after heat treatment of the cavity and additional 20 µm VEP sequence. A cathode for 5-Cell ESS cavity is concomitantly under design stage.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV001  
About • Received ※ 21 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 17 March 2022
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TUPCAV002 HOM Excitation in Spoke Resonator for SRF Studies HOM, coupling, simulation, multipactoring 435
 
  • D. Longuevergne, N. Bippus, F. Chatelet, V. Delpech, N. Hu, C. Joly, T. Pépin-Donat, F. Rabehasy, L. Renard
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • M. Baudrier
    CEA-DRF-IRFU, France
  • E. Cenni, L. Maurice
    CEA-IRFU, Gif-sur-Yvette, France
 
  The excitation of Higher Order Modes (HOM) or Lower Order Modes (LOM) has been performed for years on multi-cell superconducting accelerating cavities as a mean to coarsely locate a quench, a defective area or ignite a plasma for surface cleaning. Moreover, such multi-mode testing is very useful to understand more accurately the frequency dependence of the surface resistance in a wide range of surface magnetic fields (0<B<150mT). In that sense, several type of dedicated non-accelerating resonators like Quadrupole Resonator (QPR), Half- or Quarter- Wave resonators have been built to specifically study new superconducting materials or new surface or heat treatments. What is proposed in this paper is to perform such multi-mode analysis (352 MHz, 720 MHz and 1300 MHz) in an existing accelerating cavity, in particular a Spoke Resonator. Baseline results will be presented and perspectives of such technique will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV002  
About • Received ※ 22 June 2021 — Revised ※ 19 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 15 April 2022
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TUPCAV003 1.3 GHz Seamless Copper Cavities via CNC Spinning Technique SRF, ECR, superconductivity, experiment 440
 
  • F. Sciarrabba, O. Azzolini, G. Keppel, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • I. Calliari, R. Guggia, L. Pezzato, M. Pigato
    UNIPD, Padova, Italy
 
  The spinning process is an established technology for the production of seamless resonant cavities. The main drawback is that, so far, a manual process is adopted, so the quality of the product is subject to the worker’s skills. The Compute Numerical Controlled (CNC) applied to the spinning process can be used to limit this problem and increase the reproducibility and geometrical accuracy of the cavities obtained. This work reports the first 1.3 GHz SRF seamless copper cavities produced by CNC spinning at the Laboratori Nazionali di Legnaro of INFN. For this purpose, metrological analysis were conducted to verify the geometrical accuracy of the cavities after different steps of forming and thermal treatments; axial profile and wall thickness measurements were carried out, investigating different zones of the cavity profile. The cavities were also characterized through mechanical and microstructural analysis, to identify the effect of the automatic forming process applied to the production process of the 1.3 GHz SRF seamless copper cavities.  
poster icon Poster TUPCAV003 [1.025 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV003  
About • Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 24 December 2021
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TUPCAV004 Deflecting Cavities for Proton Beam Spreader in CiADS Project proton, superconducting-RF, dipole, linac 445
 
  • Y.L. Huang, Y. He, H. Jia, Y.S. Qin, Z.J. Wang, Z.L. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249)
Chinese initiative Accelerator Driven Subcritical System (CiADS) is supposed to accelerate continuous 162.5 MHz, 10 mA (or higher) proton beam to 500 MeV (or higher energy) with a superconducting driver linac. More application scenarios based on this high power intensity proton linac are now under considerations. Beam spreader system based on deflecting cavities for multiple users simultaneous operation are discussed in this paper, as well as the RF structure options for the equal eight- and nigh- beam-line split schemes.
#huangyulu@impcas.ac.cn
 
poster icon Poster TUPCAV004 [1.074 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV004  
About • Received ※ 21 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 13 May 2022
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TUPCAV005 Toward Qualifications of HB and LB 650MHz Cavities for the Prototype Cryomodules for the PIP-II Project cryomodule, SRF, proton, status 448
 
  • M. Martinello, D.J. Bice, C. Boffo, S.K. Chandrasekaran, G.V. Eremeev, F. Furuta, T.N. Khabiboulline, K.E. McGee, A.V. Netepenko, J.P. Ozelis, A.I. Sukhanov, G. Wu
    Fermilab, Batavia, Illinois, USA
  • M. Bagre, V. Jain, A. Puntambekar, S. Raghvendra, P. Shrivastava
    RRCAT, Indore (M.P.), India
  • M. Bertucci, A. Bosotti, C. Pagani, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • P. Bhattacharyya, S. Ghosh, S. Ghosh, A. Mandal, S. Seth, S. Som
    VECC, Kolkata, India
  • M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  • S.H. Kim, K.E. McGee, P.N. Ostroumov
    FRIB, East Lansing, Michigan, USA
  • K.K. Mistri, P.N. Prakash
    IUAC, New Delhi, India
 
  High-beta (HB) and low-beta (LB) 650 MHz cryomodules are key components of the Proton Improvement Plan II (PIP-II) project. In this contribution we present the results of several 5-cell HB650 cavities that have been processed and tested with the purpose of qualifying them for the prototype cryomodule assembly, which will take place later this year. We also present the first results obtained in LB650 single-cell cavities process optimization. Taking advantage of their very similar geometry, we are also analyzing the effect of different surface treatments in FRIB’s 5-cell medium-beta 644MHz cavities. Cavities processed with N-doping and mid-T baking showed very promising results in term of both Q-factors and accelerating gradient for these low-beta structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV005  
About • Received ※ 01 July 2021 — Accepted ※ 02 November 2021 — Issue date; ※ 16 May 2022  
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TUPCAV006 Nb3Sn Films Depositions from Targets Synthesized via Liquid Tin Diffusion target, niobium, controls, site 452
 
  • M. Zanierato, O. Azzolini, E. Chyhyrynets, V.A. Garcia Diaz, G. Keppel, C. Pira, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
 
  The deposition of Nb3Sn on copper cavities is inter-esting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. Magnetron sputtering technology allows the deposi-tion of Nb3Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require targets with non-planar shape, difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD tech-nique is a wire fabrication technology, already devel-oped in the past at LNL for SRF applications [2], that allows the deposition of very thick and uniform coat-ing on Nb substrates even with complex geometry [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb3Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work.  
poster icon Poster TUPCAV006 [5.032 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV006  
About • Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 23 August 2021 — Issue date ※ 02 September 2021
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TUPCAV009 AMR Sensors Studies and Development for Cavities Tests Magnetometry at CEA SRF, superconducting-cavity, cryogenics, controls 457
 
  • J. Plouin, E. Cenni, L. Maurice
    CEA-DRF-IRFU, France
 
  Studying flux expulsion during superconducting cavities test increases the need for exhaustive magnetometric cartography. The use of Anistropic Magneto Resistance (AMR) sensors, much cheaper than commercial fluxgates, allows the use of tens of sensors simultaneously. Such sensors are developed and sold for room temperature application but are resistant to cryogenic temperatures. However, they need proper calibration, which is more difficult at cryogenic temperature. Actually, this calibration uses the flip of the magnetization of the anisotropic ferromagnetic element, which coercitive field is increased at low temperature. We will present the development of method and software carried out at CEA for the use of such sensors, as well as the preliminary design of a rotating magnetometric device destined to elliptical cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV009  
About • Received ※ 22 June 2021 — Revised ※ 13 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 22 February 2022
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TUPCAV010 Application of the ASME Boiler and Pressure Vessel Code in the Design of SRF Cavities at Fermilab SRF, GUI, niobium, factory 460
 
  • C.S. Narug, M. Parise, D. Passarelli
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Jacketed Superconducting Radio Frequency (SRF) cavities structurally comprise of an inner niobium vessel surrounded by a liquid helium containment vessels. The pressure of the helium bath and/or its volume might be such that a jacketed SRF cavity shall be considered a system of pressure vessels. Thus, methods described in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) should be used to analyze the structural soundness of jacketed SRF cavities. This paper will report the use of the set of rules developed at Fermilab for the design of SRF cavities, such as jacketed 1.3 GHz cavities for LCLS-II HE and jacketed Single Spoke Resonator type~2 (SSR2) for PIP-II, to ensure a similar level of safety as prescribed by the ASME BPVC.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV010  
About • Received ※ 22 June 2021 — Accepted ※ 23 August 2021 — Issue date; ※ 12 December 2021  
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TUPCAV013 STC Qualification Tests of PIP-II HB650 Cavities vacuum, cryomodule, SRF, resonance 465
 
  • A.I. Sukhanov, S.K. Chandrasekaran, G.V. Eremeev, F. Furuta, S. Kazakov, T.N. Khabiboulline, T.H. Nicol, Y.M. Pischalnikov, O.V. Prokofiev, V. Roger, G. Wu, V.P. Yakovlev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
 
  Design of the high beta 650 MHz prototype cryomodule for PIP-II is currently undergoing at Fermilab. The cryomodule includes six 5-cell elliptical SRF cavities with accelerating voltage up to 20 MV and low heat dissipation (Q0 > 3.3 · 10zEhNZeHn). Characterization of performance of fully integrated jacketed cavities with high power coupler and tuner is crucial for the project. Such a characterization of jacketed cavity requires a horizontal test cryostat. The Fermilab Spoke Test Cryostat (STC) has been upgraded to accommodate testing of 650 MHz cavities. Commissioning of upgraded STC has been reported at SRF’19 conference. In this paper we present results of testing of the prototype HB650 cavity in upgraded STC facility. We characterize cavity performance and qualify it for the prototype HB650 cryomodule assembly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV013  
About • Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 04 October 2021  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPCAV014 Design of a Third Harmonic Cavity With Low R/Q for the ESR in BNL EIC HOM, multipactoring, simulation, electron 469
 
  • B.P. Xiao
    BNL, Upton, New York, USA
 
  Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
For the electron Storage Ring (ESR) of Brookhaven National Lab Electron Ion Collider (BNL EIC), beam loading is a great concern due to the high beam current together with abortion gap, especially for harmonic cavities due to higher operational frequency. There were attempts to use feedback/feedforward control, using multiple cavities with counter-phasing. A straightforward way to lower beam loading effect is to design a cavity with low R/Q. In this paper, we show such a design for the 3rd harmonic cavity for BNL EIC ESR.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV014  
About • Received ※ 22 June 2021 — Revised ※ 12 November 2021 — Accepted ※ 11 February 2022 — Issue date ※ 22 February 2022
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TUPCAV015 Performance of a Low Frequency QWR-Based SRF Gun electron, experiment, simulation, multipactoring 472
 
  • G. Chen, M.V. Fisher, M. Kedzie, M.P. Kelly, T.B. Petersen, T. Reid
    ANL, Lemont, Illinois, USA
  • X. Lu, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Superconducting radio-frequency (SRF) electron guns are generally considered to be an effective way of producing beams with high brightness and high repetition rates (or continuous wave). In this work, the 199.6 MHz quarter wave resonator (QWR)-based Wisconsin Free Electron Laser (WiFEL) superconducting electron gun was recently refurbished and tested at Argonne (ANL). The field performance of the e-gun was fully characterized. During this time, multipacting (MP) conditioning was performed for over 20 hours to overcome the hard MP barrier observed in the accelerating voltage range of 8 to 40 kV; the presence of multipacting is expected to operationally important for future e-guns. Here we simulated and studied the effect using CST* Microwave Studio and Particle Studio and compare with the measured data.
* CST Studio Suite, version 2020, https://www.cst.com.
 
poster icon Poster TUPCAV015 [4.870 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPCAV015  
About • Received ※ 21 June 2021 — Revised ※ 20 December 2021 — Accepted ※ 22 February 2022 — Issue date ※ 23 March 2022
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TUPTEV001 RF Experience from 6 Years of ELBE SRF-Gun II Operation gun, cathode, SRF, operation 477
 
  • A. Arnold, P.N. Lu, S. Ma, P. Murcek, A.A. Ryzhov, J. Schaber, J. Teichert, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
  • G. Ciovati, P. Kneisel
    JLab, Newport News, Virginia, USA
 
  At the electron accelerator for beams with high brilliance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) photoinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017 and 2018, so that more than 3000h of user beam have already been generated since 2019. During this time, a total of 20 cathodes (2 Cu, 12 Mg, 6 Cs2Te) were used, but no serious cavity degradation was observed. In this paper, we summarize the operational experience of the last 6 years of SRF gun operation, with special emphasis on the main RF properties of the cavity. This includes the evolution of QvsE, dark current, multipacting, but also mechanical properties such as Lorentz force detuning, helium pressure sensitivity as well as microphonics. The latter is closely connected to an active compensation by a so-called low-level RF feedback loop, which is also briefly presented.  
poster icon Poster TUPTEV001 [2.143 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV001  
About • Received ※ 21 June 2021 — Revised ※ 25 December 2021 — Accepted ※ 22 February 2022 — Issue date ※ 16 April 2022
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TUPTEV003 Progress of MgB2 Deposition Technique for SRF Cavities at LANL SRF, experiment, superconductivity, radio-frequency 482
 
  • P. Pizzol, L. Civale, D.N. Kelly, I. Nekrashevich, A. Poudel, H.R. Salazar, R.K. Schulze, T. Tajima
    LANL, Los Alamos, New Mexico, USA
 
  Since its discovery in 2001, Magnesium Diboride (MgB2) has had the potential to become a material for cavity manufacturing. Having a transition temperature (Tc) at ~39 K, there is a potential to operate the cavity at ~20 K with cryocoolers. This will open up a variety of applications that benefit from compact high-efficiency superconducting accelerators. We have found a 2-step deposition technique as a viable technique for cavity coating, i.e., coating of a pure boron layer with chemical vapor deposition using a diborane gas in the first step and react it with Mg vapor in the second step. In this paper, we will show some recent results with up to Tc ~38 K using a small furnace and describe a new coating system under construction with a new 3-zone furnace to coat a 1.3-GHz single-cell cavity.  
poster icon Poster TUPTEV003 [0.451 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV003  
About • Received ※ 21 June 2021 — Accepted ※ 16 October 2021 — Issue date; ※ 02 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV004 In Situ Plasma Processing of Superconducting Cavities at JLAB cryomodule, plasma, HOM, software 485
 
  • T. Powers, N.C. Brock, T.D. Ganey
    JLab, Newport News, Virginia, USA
 
  Funding: Funding provided by SC Nuclear Physics Program through DOE SC Lab funding announcement Lab-20-2310
Jefferson Lab began a plasma processing program starting in the spring of 2019. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the secondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The residuals of the hydrocarbons in the form of water, carbon monoxide and carbon dioxide are removed from the cryomodule as part of the process gas flow. The initial focus of the effort is processing C100 cavities by injecting RF power into the HOM coupler ports. We will then start investigating processing of C50 cavities by introducing RF into the fundamental power coupler. The plan is to start processing cryomodules in the CEBAF tunnel in the mid-term future, with a goal of improving the operational gradients and the energy margin of the linacs. This work will describe the systems and methods used at JLAB for processing cavities using an argon oxygen gas mixture. Before and after plasma processing results will also be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV004  
About • Received ※ 21 June 2021 — Accepted ※ 05 October 2021 — Issue date; ※ 02 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV005 PIP-II 650 MHz Power Coupler Thermal Studies cryomodule, radiation, GUI, vacuum 490
 
  • H. Jenhani, S. Arsenyev
    CEA-IRFU, Gif-sur-Yvette, France
  • S. Kazakov, N. Solyak
    Fermilab, Batavia, Illinois, USA
 
  The Proton Improvement Plan - II (PIP-II) project is underway at Fermilab with an international collaboration involving CEA in the development and testing of 650 MHz cryomodules. One of the first main contributions of the CEA was the participation in the design efforts for the current 50 KW CW 650 MHz power couplers. This paper reports some of the results of thermal and paramet-ric studies carried out by the CEA on these power couplers  
poster icon Poster TUPTEV005 [0.801 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV005  
About • Received ※ 21 June 2021 — Revised ※ 08 February 2022 — Accepted ※ 15 February 2022 — Issue date ※ 03 May 2022
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TUPTEV006 Development and Adustment of Tools for Superconducting RF Gun Cavities gun, SRF, FEL, cathode 495
 
  • B. van der Horst, D. Klinke, A. Muhs, M. Schmökel, J.K. Sekutowicz, S. Sievers, N. Steinhau-Kühl, A. Sulimov, J.H. Thie, L. Trelle, E. Vogel
    DESY, Hamburg, Germany
 
  For the superconducting radio frequency (SRF) 1.6-cell gun cavities (CV) developed at DESY, a similar fabrication and treatment process, as for the European XFEL 9-cell cavities is foreseen. The different length and geometry of these cavities lead to a number of adjustments to existing and the development of new tools. This paper covers the new designs and adaptations of a tuning tool, chemistry flanges, a wall thickness measurement device, as well as a new high-pressure rinsing spray head and an optical inspection camera for the 1.6-cell 1.3 GHz DESY SRF gun cavities under the development for the European XFEL.  
poster icon Poster TUPTEV006 [1.397 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV006  
About • Received ※ 21 June 2021 — Revised ※ 05 August 2021 — Accepted ※ 18 September 2021 — Issue date ※ 18 November 2021
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TUPTEV009 Seamless 1.3 GHz Copper Cavities for Nb Coatings: Cold Test Results of Two Different Approaches SRF, niobium, superconducting-RF, ISOL 498
 
  • L. Vega Cid, S. Atieh, L.M.A. Ferreira, L. Laín-Amador, C. Pereira Carlos, G.J. Rosaz, K. Scibor, W. Venturini Delsolaro, P. Vidal Garcia
    CERN, Meyrin, Switzerland
  • S.B. Leith
    University Siegen, Siegen, Germany
 
  A necessary condition for high SRF performances in thin film coated cavities is the absence of substrate defects. For instance, in the past, defects originated around electron beam welds in high magnetic field areas have been shown to be the cause of performance limitations in Nb/Cu cavities. Seamless cavities are therefore good candidates to allow an optimization of the coating parameters without the pitfalls of a changing substrate. In this work, we present the first results of two different methods to produce seamless cavities applied to 1.3 GHz copper single cells coated with thin Nb films by means of HIPIMS. A first method consists in electroplating the copper resonator on precisely machined aluminum mandrels, which are then dissolved chemically. As an alternative and a cross check, one cavity was machined directly from the bulk. Both cavities were coated with HIPIMS Nb films using the same coating parameters and the SRF performance was measured down to 1.8 K with a variable coupler to minimize the measurement uncertainty.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV009  
About • Received ※ 21 June 2021 — Revised ※ 28 October 2021 — Accepted ※ 18 November 2021 — Issue date ※ 10 February 2022
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TUPTEV010 Camera Placement in a Short Working Distance Optical Inspection System for RF Cavities laser, focusing, controls, SRF 503
 
  • A. Macpherson, L.R. Buonocore, M. Di Castro, H. Gamper, A. Luthi
    CERN, Geneva, Switzerland
 
  Inspection of the RF surface of cavities for the purpose of detecting surface anomalies has been well established, and is typically based on long working distance optical systems using on-axis camera and mirror systems to scan the cavity surface. In order to improve the systematic inspection of the full RF surface of large area cavities, a novel short working distance inspection system is being developed at CERN. This new system is based on a mechatronic robotic system to position that camera at normal incidence close to the cavity surface. To accommodate working distance fluctuations, and to provide increased depth of field resolution, the short working distance camera is coupled with a liquid lens focusing system, providing a programmable focusing function. Details of inspection bench design and first results are reported, as well as details on camera positioning optimisation and the proximity detection surveillance for collision-free scanning of the full-cavity surface.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV010  
About • Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 18 November 2021 — Issue date ※ 30 January 2022
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TUPTEV011 SRF Accelerating Modules Repair at DESY FEL, SRF, linac, operation 508
 
  • D. Kostin, J. Eschke, K. Jensch, N. Krupka, L. Lilje, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
    DESY, Hamburg, Germany
 
  Eight SRF cavities assembled in an accelerating module represent a building block of the particle linear accelerator based on TESLA SRF technology. DESY has two machines, European XFEL and FLASH. Both use almost same module and cavity types. During the module assembly many factors can deteriorate the cavity performance and cause a need for a repair action. Currently two European XFEL modules and two FLASH ones underwent reassembly procedures. The repair was not immediately successful on every of these modules and re-iterations did follow. The degradation causes were investigated. SRF modules were tested on both test-stands at DESY: AMTF and CMTB. The results of the described actions are presented and discussed.  
poster icon Poster TUPTEV011 [1.494 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV011  
About • Received ※ 18 June 2021 — Accepted ※ 19 November 2021 — Issue date; ※ 01 February 2022  
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TUPTEV012 Progress and Preliminary Statistics for the ESS Series Spoke Cryomodule Test cryomodule, SRF, LLRF, operation 512
 
  • H. Li, K. Fransson, K.J. Gajewski, L. Hermansson, A. Miyazaki, R.J.M.Y. Ruber, R. Santiago Kern, M. Zhovner
    Uppsala University, Uppsala, Sweden
 
  The European spallation source (ESS), as a world-class high power proton accelerator facility, will be the first one to adopt 26 double spoke resonators (DSR) at its low energy section. As a new superconducting accelerating structure, these DSRs are therefore considered key technology and a challenge for the whole project. They will be the first DSRs in the world to be commissioned for a high power proton accelerator. Since 2019, FREIA Laboratory, Uppsala university, has successfully tested the first DSR prototype cryomodule and is now in charge of the acceptance tests of the ESS series cryomodules prior to installation in the tunnel. The cryomodule test, including cryogenic and RF testing, verifies operation of the cavities, couplers and cold tuning systems. This poster will present the test results for the ESS series spoke cryomodules, including preliminary statistics, experience in general.  
poster icon Poster TUPTEV012 [0.893 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV012  
About • Received ※ 21 June 2021 — Revised ※ 18 December 2021 — Accepted ※ 06 May 2022 — Issue date ※ 06 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV013 Managing Sn-Supply to Tune Surface Characteristics of Vapor-Diffusion Coating of Nb3Sn SRF, experiment, niobium, superconductivity 516
 
  • U. Pudasaini, C.E. Reece
    JLab, Newport News, Virginia, USA
  • J.K. Tiskumara
    ODU, Norfolk, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177
Nb3Sn promises better RF performance (Q and Eacc) than niobium at any given temperature because of superior superconducting properties. Nb3Sn-coated SRF cavities are now produced routinely by growing a few microns thick Nb3Sn films inside Nb cavities via the tin vapor diffusion technique. Sn evaporation and consumption during the growth process notably affect the quality of the coating. Aiming at favorable surface characteristics that could enhance the RF performance, many coatings were produced by varying Sn sources and temperature profiles. Coupon samples were examined using different material characterization techniques, and a selected few sets of coating parameters were used to coat 1.3 GHz single-cell cavities for RF testing. The Sn supply’s careful tuning is essential to manage the microstructure, roughness, and overall surface characteristics of the coating. We summarize the material analysis of witness samples and discuss the performance of several Nb3Sn-coated single-cell cavities linked to Sn-source characteristics and observed Sn consumption during the film growth process.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV013  
About • Received ※ 21 June 2021 — Revised ※ 09 October 2021 — Accepted ※ 15 December 2021 — Issue date ※ 22 February 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV016 Upgrade of the RHIC 56 MHz Superconducting Quarter-Wave Resonator Cryomodule coupling, operation, cryomodule, HOM 522
 
  • Z.A. Conway, R. Anderson, D. Holmes, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
In preparation for the 2023 RHIC sPHENIX experi-mental program the superconducting 56 MHz quarter-wave resonator cryomodule, used operationally for longitudinal bunch compression with up to 1 MV RF voltage, is being refit to accommodate an expected beam current of 418 mA per ring, an increase of ~1.5 relative to previous operation. The upgrades to the system include an improved fundamental mode damp-er, and dual function fundamental power and higher-order mode damper couplers. This paper will describe the preliminary testing, select subsystem changes and plans for testing the cryomodule prior to installation in the RHIC beam line in 2022.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV016  
About • Received ※ 21 June 2021 — Revised ※ 09 February 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 April 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV017 Processing and Test Result of 650 MHz 50 kW CW Prototype Couplers for PIP-II Project vacuum, GUI, multipactoring, coupling 526
 
  • N. Solyak, B.M. Hanna, S. Kazakov
    Fermilab, Batavia, Illinois, USA
 
  For PIP-II project Fermilab is developing 650 MHz couplers to deliver up to 50 kW CW RF power to the superconducting low-beta (LB650) and high-beta (HB650) cavities. To meet project requirements two different designs of the couplers were proposed, one is conventional design with copper plated stainless steel walls. In second design (EM-shielded) a copper screen is used to shield stainless steel wall from electromagnetic field. For prototyping we built two couplers of each type and tested them at 50kW with full reflection at different reflection phases. In each test the assembly of two couplers were processed with DC bias up to +5 kV, starting with short pulses and ramping power up to 100 kW. Final run for 2 hours in CW mode at 50 kW to reach equilibrium temperature regime and qualify couplers. One pair of couplers was also processed without DC bias. Finally, all four couplers demonstrated full requirements and were qualified. Based on test results the conventional coupler with some modification was chosen as a baseline design. Modified version of coupler is now ordered for prototype of HB650 cryomodule. In paper we will discuss details of coupler processing and results  
poster icon Poster TUPTEV017 [2.206 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV017  
About • Received ※ 21 June 2021 — Revised ※ 06 August 2021 — Accepted ※ 19 November 2021 — Issue date ※ 08 December 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV018 Status of RF Power Coupler for HWR in RISP cryomodule, status, vacuum, simulation 531
 
  • S. Lee, M. Lee, Y.U. Sohn
    IBS, Daejeon, Republic of Korea
  • Y.U. Sohn
    PAL, Pohang, Republic of Korea
 
  Funding: This work was supported by the Rare Isotope Science Project of Institute for Basic Science funded by Ministry of Science and ICT and NRF of Korea 2013M7A1A1075764.
A heavy-ion accelerator facility is under construction for Rare Isotope Science Project(RISP) in Korea. Four types of super conducting cavities, QWR, HWR, SSR1, and SSR2 are developed to accelerate the ion beams. The QWR cryomodule is already installed in the tunnel. The HWR cryomodule is transport to the tunnel. Here, the status of HWR RF power coupler is presented. After the fabrication, the coupler is test with high power RF. The some of the test results are described.
 
poster icon Poster TUPTEV018 [1.735 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-TUPTEV018  
About • Received ※ 21 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 29 April 2022
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WEPFAV001 Cryomodule Development for the Materials Irradiation Facility: From IFMIF-EVEDA to IFMIF-DONES cryomodule, vacuum, linac, solenoid 534
 
  • N. Bazin, S. Chel
    CEA-DRF-IRFU, France
 
  For several years, CEA has been involved in the development of superconducting linac for fusion related project, with the goal to develop an high flux neutrons source to test and qualify specific materials to be used in fusion power plants. In the framework of the ITER Broder Approch, a prototype cryomodule is under construction in Japan for the IFMIF/EVEDA phase(Engineering Validation and Engineering Design Activities) and the construction of the Accelerator Prototype (LIPAc) at Rokkasho, fully representative of the IFMIF low energy (9 MeV) accelerator (125 mA of D+beam in continuous wave). Meanwhile, the design studies of a plant called DONES (Demo Oriented NEutron Source, derived from IFMIF) started, with a superconducting linac made of 5 cryomodules. These one are based on the same principles as the one developed for IFMIF/EVEDA, but taking into account the lessons learnt from the prototype. This paper will present the similarities but also the differences between the cryomodules for IFMIF/EVEDA and DONES.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFAV001  
About • Received ※ 28 June 2021 — Revised ※ 23 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 13 October 2021
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WEPFAV005 Design Optimization of the 166-MHz and 500-MHz Fundamental Power Couplers for Superconducting RF Cavities at High Energy Photon Source multipactoring, simulation, cryogenics, photon 544
 
  • T.M. Huang, Chang, Z.Z. Chang, L. Guo, H.Y. Lin, Q. Ma, W.M. Pan, P. Zhang, X.Y. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: Supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China under Grant 12075263.
Five 166-MHz quarter-wave ß=1 cavities have been chosen for the fundamental srf system while two 500-MHz single-cell elliptical cavities for the third-harmonic system for High Energy Photon Source (HEPS). Each cavity will be equipped with one fundamental power coupler (FPC) capable of delivering 250-kW continuous-wave rf power. For the 166-MHz FPC, two prototypes were developed and excellent performances were demonstrated in the high-power operations. However, the inner air part was observed to be warmer than predictions. Therefore, an innovative cooling scheme was adopted. In addition, the Nb extension tube has been elongated to solve the overheating in the cavity-coupler interface region. Concerning the 500-MHz FPC, several improvements were proposed. First, a doorknob adopting WR1800 instead of WR1500 waveguide was chosen to better match the operating frequency; Second, the window position was optimized to ensure multipacting-free on the window; Third, the cryogenic heat load was estimated carefully to obtain an optimum helium gas cooling. The main parameters and the design optimizations of the 166-MHz and 500-MHz FPCs are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFAV005  
About • Received ※ 21 June 2021 — Accepted ※ 21 August 2021 — Issue date; ※ 20 January 2022  
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WEPFAV006 ILC Energy Upgrade Paths to 3 TeV linac, SRF, klystron, cryomodule 549
 
  • H. Padamsee
    Fermilab, Batavia, Illinois, USA
 
  We consider ILC upgrade paths beyond 1 TeV: (1) to 2 TeV and (2) to 3 TeV depending on the needs of high energy physics. Parameters for four scenarios will be presented and challenges discussed. 1. From 1 TeV to 2 TeV based on: a. Gradient advances of Nb cavities to 55 MV/m anticipated from on-going SRF R&D on Nb structures discussed in Section 4.3.x. b. Radically new travelling wave (TW) superconducting structures [1,2] optimized for effective gradients of 70+ MV/m, along with 100% increase in R/Q (discussed in more detail in Section 4.3.x). The large gain in R/Q has a major beneficial impact on the refrigerator heat load, the RF power, and the AC operating power. OR 2. From 1 TeV to 3 TeV based on a. Radically new travelling wave (TW) superconducting structures [1,2] optimized for effective gradients of 70+ MV/m, along with 100% increase in R/Q. The large gain in R/Q has a major beneficial impact on heat load, RF power, and the AC operating power. b. 80 MV/m gradient potential for Nb3Sn [3] with Q of 1x1010, based on extrapolations from high power pulsed measurements on single cell Nb3Sn cavities. Further, the operating temperature is 4.2 K instead of 2K.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFAV006  
About • Received ※ 13 June 2021 — Accepted ※ 29 September 2021 — Issue date; ※ 16 May 2022  
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WEPFDV004 A New Model for Q-Slope in SRF Cavities: RF Heating at Multiple Josephson Junctions at Weakly Linked Grain Boundaries or Dislocations SRF, data-analysis, ECR, electron 556
 
  • K. Saito
    KEK, Ibaraki, Japan
  • K. Saito
    FRIB, East Lansing, Michigan, USA
 
  Several models are already proposed for Q-slopes in SRF cavity performance, medium field Q-slope (MFQS), high field Q-slope (HFQS). However, these does not explain both in a way unified. Here, a new model by multiple Josephson junctions on weakly linked grain boundaries or dislocations is proposed for the unified explanation. This model suggests two kind of junctions: ceramic like one and weak superconductor one. If plotted the field vs. RF power dissipation, an increase of RF loss is remarkably observed in proportional to the cube of fields, on both BCP’ed and EP’ed cavity (MFQS). An exponential RF dissipation is often observed at high fields for BCP’ed cavity (HFQS). If supposed the number of J-junctions linearly increases with the fields (this is explained by the flux quantum penetration condition), these behaviors are easily explained. In addition, this model has a potential to explain the anti-Q slope behavior observed in Nitrogen doped or mid-temperature baked cavity. In this paper, this model will be explained, then several data analysis results will be presented.  
poster icon Poster WEPFDV004 [2.196 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV004  
About • Received ※ 21 June 2021 — Accepted ※ 11 November 2021 — Issue date; ※ 16 May 2022  
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WEPFDV005 Tensile Tests of Large Grain Ingot Niobium at Liquid He Temperature niobium, experiment, SRF, radio-frequency 562
 
  • M. Yamanaka
    KEK, Ibaraki, Japan
  • K. Enami
    Tsukuba University, Ibaraki, Japan
 
  Tensile tests at liquid He temperature were performed using specimen taken from high purity large grain niobium ingot produced by CBMM. The measured RRR is 242. The ingot is 260 mm in diameter and sliced by a multi wire saw to 2.8 thickness. 5 specimens were cut off from one sliced disk. 3 disks were set in same phase to obtain same grain distribution. 3 specimens each of 5 grain patterns 5, 15 in total were used for the tensile test. The tensile test stand using a cryostat and liquid He was manufactured by ourselves. The measured tensile strength varied 379 to 808 MPa. The average value is 611 MPa. The tensile strength at room temperature is 84 MPa. The strength becomes high at low temperature like a fine grain niobium. The specimen includes a grain boundary, and causes the variation of strength. The different result was obtained in same grain patterns. The relationship between crystal orientation and strength is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV005  
About • Received ※ 08 June 2021 — Accepted ※ 12 September 2021 — Issue date; ※ 02 May 2022  
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WEPFDV006 Activities at NCBJ Towards Development of the Future, Fully-Superconducting, XFEL-Type, RF Electron Gun cathode, gun, electron, plasma 566
 
  • J. Lorkiewicz, P.J. Czuma, A.M. Kosińska, P. Krawczyk, R.M. Mirowski, R. Nietubyć, M. Staszczak, K. Szamota-Leandersson
    NCBJ, Świerk/Otwock, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
 
  Our group at NCBJ works on upgrade of 1.6-cell, SRF, XFEL-type injector in collaboration with DESY and other laboratories. The work is focused on preparation of lead-on-niobium photocathode, its positioning in the gun cavity and on the UV laser system for photocurrent excitation. RF focusing effect was used to minimize the predicted emittance and transverse size of accelerated e- beam. Following beam dynamics computation, it has been proposed that the photocathode be recessed 0.45 mm into the rear wall of the gun cavity. It helps focusing e- beam in its low-energy part. Preparation of sc cathodes of Pb layer on Nb plugs (*, **) is reported, aimed at reaching clean, planar and uniform Pb films. The laser system will consist of commercially available Pharos laser and a 4-th harmonic generator. A gaussian, 300 fs long, 257 nm in wavelength UV pulse will be transformed in time by a pulse stretcher/stacker and in space by pi-shaper. The planned optical system will generate cylindrical photoelectron bunch 2 - 30 ps long and 0.2 - 3 mm wide.
* J. Lorkiewicz et al., Vacuum 179 (2020) 109524
** R. Nietubyc et al., NIM A891 (2018) pp. 78-86
 
poster icon Poster WEPFDV006 [2.014 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV006  
About • Received ※ 21 June 2021 — Accepted ※ 13 April 2022 — Issue date; ※ 03 May 2022  
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WEPFDV007 Main Highlights of ARIES WP15 Collaboration SRF, site, laser, radio-frequency 571
 
  • O.B. Malyshev, P. Goudket, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • O. Azzolini, E. Chyhyrynets, G. Keppel, C. Pira, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  • G. Burt, D.J. Seal, D.A. Turner
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • G. Burt, B.S. Sian
    Lancaster University, Lancaster, United Kingdom
  • O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • S.B. Leith, A.O. Sezgin, M. Vogel
    University Siegen, Siegen, Germany
  • A. Medvids, P. Onufrijevs
    Riga Technical University, Riga, Latvia
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
  • B.S. Sian
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal Garcia
    CERN, Meyrin, Switzerland
  • D.A. Turner
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  Funding: European Commission’s ARIES collaboration H2020 Research and Innovation Programme under Grant Agreement no. 730871
An international collaboration of research teams from CEA (France), CERN (Switzerland), INFN/LNL (Italy), HZB and USI (Germany), IEE (Slovakia), RTU (Latvia) and STFC/DL (UK), are working together on better understanding of how to improve the properties of superconducting thin films (ScTF) for RF cavities. The collaboration has been formed as WP15 in the H2020 ARIES project funded by EC. The systematic study of ScTF covers: Cu substrate polishing with different techniques (EP, SUBU, EP+SUBU, tumbling, laser), Nb, NbN, Nb3Sn and SIS film deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application of all obtained knowledge on polishing, deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application to the QPR samples for testing the films at RF conditions. The preparation, deposition and characterisation of each sample involves 3-5 partners enhancing the capability of each other and resulting in a more complete analysis of each film. The talk will give an overview of the collaborative research and will be an introduction to the detailed talks given by the team members.
 
poster icon Poster WEPFDV007 [2.008 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV007  
About • Received ※ 19 June 2021 — Accepted ※ 12 February 2022 — Issue date; ※ 10 April 2022  
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WEPFDV008 Thermal Conductivity of Electroplated Copper Onto Bulk Niobium at Cryogenic Temperatures SRF, niobium, site, radio-frequency 576
 
  • G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  • I.P. Parajuli, M.R.P. Walive Pathiranage
    ODU, Norfolk, Virginia, USA
  • T. Saeki
    KEK, Ibaraki, Japan
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Superconducting radio-frequency (SRF) cavities made of high-purity bulk niobium are widely used in modern particle accelerators. The development of metallic outer coatings with high thermal conductivity would have a beneficial impact in terms of improved thermal stability, reduced material cost and for the development of conduction-cooled, cryogenic-free SRF cavities. Several high-purity, fine-grain Nb samples have been coated with 2’4 mm thick copper by electroplating. Measurements of the thermal conductivity of the bimetallic Nb/Cu samples in the range 2’7 K showed values of the order of 1 kW/(m K) at 4.3 K. Very good adhesion between copper and niobium was achieved by depositing a thin Cu layer by cold spray on the niobium, prior to electroplating the bulk Cu layer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV008  
About • Received ※ 17 June 2021 — Accepted ※ 10 September 2021 — Issue date; ※ 01 March 2022  
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WEPFDV010 Structural Investigation of Nitrogen-Doped Niobium for SRF Cavities niobium, SRF, superconducting-RF, operation 581
 
  • M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H18RDRB2 and the German Research Foundation (DFG) via the AccelencE Research Training Group (GRK 2128).
Niobium is the standard material for superconducting RF (SRF) cavities for particle acceleration. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram, the cubic delta-phase of NbN has the highest critical temperature. Niobium samples were annealed and doped with nitrogen in the high-temperature furnace at TU Darmstadt and investigated at its Materials Research Department with respect to structural modifications. X-ray diffraction (XRD) confirmed the appearance of Nb4N3 and Nb2N phases on the surface of the samples. A single cell cavity was annealed under optimized doping conditions. The test samples treated together with the cavity showed almost single Nb4N3 phase. XRD pole figures also showed grain growth during sample annealing.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV010  
About • Received ※ 22 June 2021 — Revised ※ 18 August 2021 — Accepted ※ 17 November 2021 — Issue date ※ 19 November 2021
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WEPCAV001 Study of the Niobium Oxide Structure and Microscopic Effect of Plasma Processing on the Niobium Surface plasma, niobium, background, ECR 585
 
  • B. Giaccone, M. Martinello
    Fermilab, Batavia, Illinois, USA
  • B. Giaccone, J. Zasadzinski
    IIT, Chicago, Illinois, USA
 
  A study of the niobium oxide structure is presented here, with particular focus on the niobium suboxides. Multiple steps of argon sputtering and XPS measurements were carried out until the metal surface was exposed. The sample was then exposed to air and the oxide regrowth was studied. In addition, three Nb samples prepared with different surface treatments were studied before and after being subjected to plasma processing. The scope is investigating the microscopic effect that the reactive oxygen contained in the glow discharge may have on the niobium surface. This study suggests that the Nb2O5 thickness may increase, although no negative change in the cavity performance is measured since the pentoxide is a dielectric.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV001  
About • Received ※ 22 June 2021 — Revised ※ 13 September 2021 — Accepted ※ 13 January 2022 — Issue date ※ 16 May 2022
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WEPCAV002 Improvement of Chemical Etching Capabilities (BCP) for SRF Spoke Resonators at IJCLab simulation, HOM, SRF, niobium 590
 
  • J. Demercastel-Soulier, P. Duchesne, D. Longuevergne, G. Olry, T. Pépin-Donat, F. Rabehasy, D. Reynet, S. Roset, L.M. Vogt
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
 
  Buffered chemical polishing (BPC) is the reference surface polishing adopted for ESS and MYRRHA SRF spoke resonators at IJCLab. This chemical treatment, in addition to improving the RF performance, fits into the frequency adjustment strategy of the jacketed cavity during its preparation phase. In the framework of the collaboration with Fermilab for PIP-II project, IJCLab has developed a new setup to perform rotational BCP. The implementation of a rotation during chemical etching improves significantly the homogeneity and quality of surface polishing. In this paper, we present the numerical analysis based on a fluid dynamics model. The goal is to estimate the acid flow characteristics inside the cavity, determine the influence of several parameters as mass flow rate and rotation speed and propose the best configuration for the new experimental setup  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV002  
About • Received ※ 23 June 2021 — Revised ※ 18 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 January 2022
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WEPCAV006 650 MHz Elliptical Cavities in IMP for CiADS Project niobium, linac, simulation, proton 594
 
  • Y.L. Huang, H. Guo, Y. He, C.L. Li, R.X. Wang, Z.J. Wang, M. Xu, Z.Q. Yang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: Large Research Infrastructures "China initiative Accelerator Driven System"(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249)
650MHz multi-cell superconducting elliptical cavities with optimum beta equal to 0.62 and 0.82 were adopted in the driver linac of Chinese initiative Accelerator Driven Subcritical System (CiADS) to accelerate the 10 mA proton beam from 175 MeV up to 500 MeV, with the possibility to upgrade the energy to 1 GeV and higher. Mechanical design and optimization of the niobium cavity-titanium helium vessel assembly will be summarized in this paper. Vertical test results of three single cell prototype cavities will also be discussed, with comparisons with the simulation values.
*Work supported by Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249)
 
poster icon Poster WEPCAV006 [1.389 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV006  
About • Received ※ 21 June 2021 — Revised ※ 10 December 2021 — Accepted ※ 05 February 2022 — Issue date ※ 07 April 2022
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WEPCAV007 Status and First Tests of the Reduced-Beta Capture Cavity for the S-DALINAC linac, electron, SRF, operation 597
 
  • S. Weih, M. Arnold, M. Dutine, J. Enders, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
 
  Funding: work supported by German research council (DFG) through GRK 2128 ’AccelencE’ and the state of Hesse through the LOEWE research project Nuclear Photonics and the Collaborative Research Cluster ELEMENTS
The superconducting part of the injector section of the superconducting Darmstadt electron linear accelerator (S-DALINAC) [1] consisted of one five-cell capture cavity and two 20-cell cavities at 3 GHz resonance frequency. All of them were geometrically adapted to electron velocities with a beta of 1, while the thermionic gun provides electrons with a beta of 0.74. This mismatch resulted in an insufficient capture process for optimum beam quality. For this reason, a new six-cell capture cavity with a beta of 0.86 has been designed and built. Field flatness tuning, a test in the vertical bath cryostat, and a UHV furnace treatment have been carried out in-house to finalize the cavity processing. The cryostat module was adapted to house the new cavity, which has been recently installed. Following the module assembly, a first RF test run was conducted at the S-DALINAC. We report on these latest advancements towards the implementation of the injector upgrade.
* N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV007  
About • Received ※ 20 June 2021 — Revised ※ 22 December 2021 — Accepted ※ 27 February 2022 — Issue date ※ 01 March 2022
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WEPCAV008 A Fast Mechanical Tuner for SRF Cavities SRF, controls, acceleration, coupling 600
 
  • S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  There is a particular need for fast tuners and phase shifters for advanced superconducting accelerator RF systems. The tuners based on ferrite, ferroelectric and piezo materials are commonly used. However, those methods suffer from one or another issue of high power loss, slow response, and narrow tuning range. We propose a robust, fast (up to ~5 MHz/sec), high efficient mechanical tuner for SRF cavities operating at the frequency 50 MHz. We develop an external mechanical tuner that is strongly coupled to the cavity. The tuner design represents a trade-off of high efficiency (low RF losses and low heat flux) and frequency tunability range. Our approach solves this trade-off issue. We propose RF design which exploits two coupled resonators so that a main high-field cavity is controlled with a small tunable resonator with a flexible metallic wall operating in a relatively low RF field. Simulations, carried out for a 7.5 MV/m 50 MHz SRF Quarter Wave Resonator (QWR), show that frequency tunability at level 10-3 is obtainable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV008  
About • Received ※ 17 June 2021 — Revised ※ 06 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 04 February 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPCAV009 Conceptual Design of Balloon Double Spoke Resonator electron, accelerating-gradient, linac, heavy-ion 604
 
  • Z.Y. Yao, R.E. Laxdal
    TRIUMF, Vancouver, Canada
 
  Funding: TRIUMF receives funding via a contribution through the National Research Council Canada.
The balloon variant of the spoke resonator was proposed to eliminate the intensive multipacting (MP) barriers around the operating field level by modifying the local electro-magnetic (EM) fields. TRIUMF has previously reported the prototyping of a 325MHz β=0.3 single spoke resonator (SSR) that demonstrated the principle of the balloon concept. To extend the benefits of the balloon variant to multi-spoke resonators, this paper will report a conceptual design of a 325MHz β=0.5 balloon double spoke resonator (DSR). The consequences from the balloon SSR design, such as the relations between EM field distributions and the field levels of the MP barriers, were applied to the DSR design. Other particular geometry features were also added due to the characters of DSRs. The simulated MP barriers were significantly squeezed to the lower field level compared to a conventional DSR design. Simulation results and conceptual design will be reported.
 
poster icon Poster WEPCAV009 [2.260 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV009  
About • Received ※ 22 June 2021 — Revised ※ 20 December 2021 — Accepted ※ 01 March 2022 — Issue date ※ 18 April 2022
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WEPCAV010 Comparison of Electromagnetic Properties During Fabrication of Copper and Niobium Prototypes of 325 MHz Coaxial Half-Wave Resonator niobium, experiment, controls, electron 609
 
  • D. Bychanok, V. Bayev, S. Huseu, S.A. Maksimenko, A.E. Sukhotski, E. Vasilevich
    INP BSU, Minsk, Belarus
  • A.V. Butenko, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • M. Gusarova, M.V. Lalayan, S.M. Polozov
    MEPhI, Moscow, Russia
  • V.S. Petrakovsky, A.I. Pokrovsky, A. Shvedov, S.V. Yurevich
    Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
  • Y. Tamashevich
    HZB, Berlin, Germany
 
  The main fabrication stages of niobium and copper prototypes of coaxial half-wave resonators (HWR) operating at frequency 325 MHz for the Nuclotron-based Ion Collider fAcility (NICA) injector are presented and discussed. Results of intermediate measurements and electromagnetic properties control for niobium and copper cavities of equivalent geometrical characteristics are compared and analyzed. The comparison of electromagnetic properties of Cu- and Nb-prototypes allows estimating specific features and differences of intermediate "warm" measurements of niobium and copper cavities. The presented results will be used for further development and production of superconductive niobium cavities with a similar design for the NICA-project.  
poster icon Poster WEPCAV010 [3.180 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV010  
About • Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 27 December 2021 — Issue date ※ 05 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPCAV011 Present Status of the Spoke Cavity Prototyping for the JAEA-ADS Linac linac, niobium, SRF, electron 612
 
  • J. Tamura, Y. Kondo, F.M. Maekawa, S.I. Meigo, B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Dohmae, E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  The Japan Atomic Energy Agency (JAEA) is proposing an accelerator-driven subcritical system (ADS) for efficient reduction of high-level radioactive waste generated in nuclear power plants. One of the challenging R¥&Ds for ADS is the reliability of the accelerator. In preparation for the full-scale design of the proton linac for the JAEA-ADS, we are now prototyping a single-spoke cavity for low-beta (around 0.2) beam acceleration. As there is no experience of manufacturing a superconducting spoke cavity in Japan, the cavity prototyping and performance testing are essential to ensure the feasibility of the JAEA-ADS linac. To proceed to an actual cavity fabrication, we have carefully reviewed the fabrication process. And then, we examined the electron-beam welding using niobium test pieces and investigated the welding condition for realizing the smooth underbead. We have finally started the press forming of niobium sheets and the machine work to shape the cavity parts. Now, we are parparing for the electron-beam welding of the shaped niobium parts.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV011  
About • Received ※ 02 July 2021 — Revised ※ 30 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 28 March 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPCAV012 Research and Development of 650 MHz Cavities for CEPC HOM, cryomodule, SRF, electron 616
 
  • P. Sha, C. Dong, F.S. He, S. Jin, Z.Q. Li, B.Q. Liu, Z.H. Mi, W.M. Pan, J.Y. Zhai, X.Y. Zhang, H.J. Zheng
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work was supported by the National Key Programme for S&T Research and Development (No. 2016YFA0400400), the Platform of Advanced Photon Source Technology R&D.
650 MHz 2-cell superconducting cavities are proposed for the main ring of the Circular Electron Positron Collider (CEPC). The design, fabrication, surface treatment (buffered chemical polishing) and vertical tests of the cavities with HOM couplers were conducted. The performance of the cavity at 2 K is not affected by the HOM coupler. The maximum intrinsic quality factor of the cavity with the HOM coupler reached 3.1·1010 at 20 MV/m. The vertical test results showed that the fundamental mode external quality factor of all HOM couplers is an order of magnitude larger than quality factor of the cavity. The HOM damping results for the 650 MHz 2-cell cavity were also measured at cryogenic temperature and compared with the simulated and measured results at room temperature. Two 650 MHz 2-cell cavities jacketed have been integrated into a test cryomodule for CEPC. Another 650 MHz 2-cell cavity reached 6·1010 at 22 MV/m after nitrogen infusion. In addition, two 650 MHz 1-cell cavities reached 2.7·1010 at 35 MV/m (fine grain) and 3.6·1010 at 32 MV/m (large grain) after electro-polishing, respectively. In future, electro-polishing will be applied to 650 MHz 2-cell cavity soon.
 
poster icon Poster WEPCAV012 [1.956 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV012  
About • Received ※ 21 June 2021 — Accepted ※ 07 December 2021 — Issue date; ※ 02 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPCAV013 Occurring Dependency between Adjustable Coupling and Q0 - Finding and Solving a Problem during Vertical Cavity Testing at DESY coupling, SRF, resonance, vacuum 619
 
  • Y.F. Liu, C. Luo
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • D. Reschke, L. Steder, M. Wiencek
    DESY, Hamburg, Germany
 
  In the AMTF (Accelerator Module Test Facility) hall at DESY, various types of cavities have been tested for different accelerators and R&D projects during the last years. For R&D purposes, dedicated inserts with additional auxiliaries like a movable INPUT antenna can be used to perform accurate measurements at different temperatures between 1.4 K and 4 K. Since 2017 more than hundred vertical tests were conducted in these inserts without troubles besides rare expected occurrences of cold leaks or even rarer a loose antenna. However, in the last months, an unexpected dependency between the measured quality factor and the coupling coefficient ß has been observed. In order to understand the source of this measurement uncertainty, several different special checks have been performed. In a logical sequence of measurements with different cryostats, inserts and cavities the problem has been encircled and in the end was identified and solved. In this paper, the observed problem is described in detail as well as the entire path leading to its solution.  
poster icon Poster WEPCAV013 [1.073 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV013  
About • Received ※ 18 June 2021 — Revised ※ 18 October 2021 — Accepted ※ 18 October 2021 — Issue date ※ 22 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPCAV014 HOM Damper Design for BNL EIC 197 MHz Crab Cavity HOM, impedance, GUI, cryomodule 624
 
  • B.P. Xiao, Q. Wu
    BNL, Upton, New York, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
  • S. Verdú-Andrés
    Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
 
  Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The interaction region (IR) crab cavity system is a special RF system to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point (IP) for BNL EIC. There will be six crab cavities, with four 197 MHz crab cavities and two 394 MHz crab cavities, installed on each side of the IP in the proton/ion ring, and one 394 MHz crab cavity on each side of the IP in the electron ring. Both rings share identical 394 MHz crab cavity design to minimize the cost and risk in designing a new RF system, and it will be scaled from 197 MHz crab cavity. In this paper, the HOM damper design for 197 MHz crab cavity is introduced.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV014  
About • Received ※ 22 June 2021 — Revised ※ 17 October 2021 — Accepted ※ 17 December 2021 — Issue date ※ 07 April 2022
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WEPCAV015 Refurbishment and Testing of the WiFEL E-Gun at Argonne FEL, gun, electron, SRF 627
 
  • T.B. Petersen, G. Chen, M.V. Fisher, M. Kedzie, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  We report on the refurbishment and testing of the Wisconsin Free Electron Laser (WiFEL) superconducting radiofrequency electron gun with application as an electron injector for DOE accelerators and as a possible future stand-alone tool for electron microscopy. Initial testing at ANL showed the cavity had a very low quality factor, ~107, later determined to be due to contamination some-time since the initial assembly. Following ultrasonic cleaning, high-pressure water rinsing, reassembly, and cold testing, the e-gun has largely recovered with Q~109 and surface electric fields ~15 MV/m. We intend that WiFEL be available as a testbed for future high brightness sources and, in particular, for testing an SRF gun photocathode loader design; an essential, and as yet, not sufficiently proven technology. We report here on many operationally important properties of a quarter-wave SRF cavity for application as an e-gun, including microphonics, pressure sensitivity, and mechanical tuning. New electromagnetic simulations show that the WiFEL cavity shape and design can be optimized in several respects.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPCAV015  
About • Received ※ 21 June 2021 — Revised ※ 23 October 2021 — Accepted ※ 07 April 2022 — Issue date ※ 07 April 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV002 High Power Coupler Devepment for EIC multipactoring, SRF, detector, simulation 632
 
  • W. Xu, Z.A. Conway, J.M. Fite, D. Holmes, K.S. Smith, A. Zaltsman
    BNL, Upton, New York, USA
 
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The future EIC Electron storage ring at BNL needs to compensate up to 10 MW synchrotron loss with RF systems. The RF system relies on 34 fundamental power couplers to deliver RF power from power sources at room temperature to 17 SRF cavities at 2 K. Each power coupler will operate with 400 kW forward power, with full reflection for ~10% of time. We are developing two 1 MW coaxial FPCs at BNL, one with a BeO window and the other with an Al2O3 window. This paper will briefly summarize test results of high power test on the BeO window FPC , and then describe the development status of the Al2O3 window FPC.
 
poster icon Poster WEPTEV002 [3.393 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV002  
About • Received ※ 25 June 2021 — Revised ※ 28 January 2022 — Accepted ※ 05 April 2022 — Issue date ※ 12 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV007 Review of the Application Piezoelectric Actuators for SRF Cavity Tuners SRF, operation, cryogenics, vacuum 642
 
  • Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authorized by Fermi Research Alliance LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy
Large SRF Linacs and HEP experiments require accurate frequency control, which is achieved using cavity tuners typically actuated by the piezoelectric ceramic stacks. The piezoelectric ceramic stacks became ’standard’ components of the SRF cavity tuner and, depending on the application, could be operated in the different environment: in air, at cryogenic temperature, in vacuum, and submerged in liquid helium. Different applications place different requirements on the piezo actuators, but the important parameters, common to all applications, are the lifetime and reliability of the actuators. Several R&D programs targeting the development of reliable piezo actuators are reviewed in this contribution.
 
poster icon Poster WEPTEV007 [1.215 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV007  
About • Received ※ 22 June 2021 — Revised ※ 27 August 2021 — Accepted ※ 18 September 2021 — Issue date ※ 22 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV008 VSR Demo Cold String: Recent Developments and Manufacturing Status HOM, SRF, operation, GUI 647
 
  • N.W. Wunderer, V. Dürr, A. Frahm, H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples-Milne, A.V. Tsakanian, A.V. Vélez
    HZB, Berlin, Germany
  • M. Bonezzi, A. D’Ambros, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • J. Guo, J. Henry, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • A.V. Vélez
    Technical University Dortmund, Dortmund, Germany
 
  The BESSY VSR project aims to demonstrate the possibility to simultaneously run both long (15ps) and short bunches (1.7ps) within BESSY II storage ring. To achieve this, a new SRF cavity system with higher harmonic cavities (3 and 3.5 harm.) needs to be installed. The combined cavity SRF beating allows for stable bunch shortening for half of the buckets while standard lengths remaining for the other half. These SRF cavities will be equipped with waveguide-connected HOM absorbers and will be controlled with a blade tuner plus piezos. To demonstrate the feasibility of this complex system the VSR DEMO cold string consists of two 1.5 GHz cavities, each featuring five waveguides and a higher power coupler, plus all interconnecting elements coupled to the beam vacuum. For most of these components the fundamental development work is completed and has been reported in the past. This paper summarizes recent enhancements, component detailing and manufacturing status. The key cold string components such as cavities, higher power couplers and blade tuners have already entered the manufacturing phase. All other cold string components will be ready for purchase at the latest beginning of 2022.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV008  
About • Received ※ 18 June 2021 — Revised ※ 09 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 05 January 2022
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WEPTEV009 The 1.5 GHz Coupler for VSR DEMO: Final Design Studies, Fabrication Status and Initial Testing Plans SRF, HOM, coupling, operation 652
 
  • E. Sharples-Milne, V. Dürr, J. Knobloch, S. Schendler, A.V. Vélez, N.W. Wunderer
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • A.V. Vélez
    Technical University Dortmund, Dortmund, Germany
 
  The variable pulse length storage ring demo (VSR DEMO) is a research and development project at the Helmholtz Zentrum Berlin (HZB) to develop and validate a 1.5 GHz SRF system capable of accelerating high CW currents (up to 300 mA) at high accelerating fields (20 MV/m) for application in electron storage rings. Such a system can be employed to tailor the bunch length in synchrotron light source such as BESSY II. VSR DEMO requires a module equipped with two 1.5 GHz 4-cell SRF cavities and all ancillary components required for accelerator operations. This includes one 1.5 GHz fundamental power coupler (FPC) per cavity, designed to handle 16 kW peak and 1.5 kW average power. The final design studies, fabrication status and initial testing plans for these FPCs will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV009  
About • Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 09 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV011 Development of In-Situ Plasma Cleaning for the FRIB SRF Linac plasma, electron, cryomodule, operation 657
 
  • C. Zhang, W. Chang, K. Elliott, W. Hartung, S.H. Kim, J.T. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, Michigan, USA
 
  Development of techniques for in-situ plasma cleaning of quarter-wave and half-wave resonator cryomodules is underway at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. If SRF cavity performance degradation is seen during future FRIB linac operation, in-situ plasma cleaning may help to restore performance without disassembly of the cavities from the cryomodules for off-line cleaning. A plasma cleaning feasibility study for FRIB cryomodules indicates that plasma cleaning can be done on-line without modifications to the RF couplers or cryomodules. Initial bench measurements have been performed on a FRIB half-wave resonator using noble gases (Ne, Ar), with and without added oxygen gas. The plasma ignition threshold has been measured as a function of gas pressure and composition. Studies of plasma cleaning efficacy are underway. Results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV011  
About • Received ※ 04 July 2021 — Revised ※ 08 November 2021 — Accepted ※ 24 December 2021 — Issue date ※ 01 March 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV012 Characterization of Atomic-Layer-Deposited NbTiN and NbTiN/AlN Films for SIS Multilayer Structures interface, SRF, site, superconductivity 662
 
  • Z. Sun, M. Liepe, T.E. Oseroff
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • X. Deng
    University of Virginia, Charlottesville, Virginia, USA
 
  SIS (superconductor-insulator-superconductor) mul-tilayer structures are proposed designs to repel early flux penetration and ease the impact of defects in SRF cavities. The demonstration of such device physics is strongly affected by the film qualities ’ material struc-ture and composition. Here, we characterized 100 nm NbTiN / 2 nm AlN / bulk Nb SIS structures and investigated the effect of the presence of the AlN layer on the NbTiN film properties. We find that the hcp-structured AlN layer results in a Nb composition gra-dient as a function of film depth, whereas the Nb con-centration remains constant in the NbTiN/Nb samples, which suggests that interface mismatch could induce significant change in NbTiN composition. The surface composition variation further leads to different oxide structures, which might impact the superconducting performance. Our observations indicate that the choice of the insulating layer in SIS structures is critical, and that interface mismatch together with internal strain could deteriorate the superconducting film.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV012  
About • Received ※ 08 July 2021 — Revised ※ 06 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 02 January 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV013 New Frequency-Tuning System and Digital LLRF for Stable and Reliable Operation of SRILAC cryomodule, controls, operation, linac 666
 
  • K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  • H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, H. Nakai, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  The superconducting booster linac at RIKEN (SRILAC) has ten 73-MHz quarter-wavelength resonators (QWRs) that are contained in three cryomodules. The beam commissioning of SRILAC was successfully performed in January 2020. Frequency tuning during cold operation is performed by compressing the beam port of the cavity with stainless wires and decreasing the length of each beam gap, similar to the method adopted at ANL and FRIB. However, each tuner is driven by a motor connected to gears, instead of using gas pressure. Since the intervals of the QWRs are small due to the beam dynamics, a compact design for the tuner was adopted. Each cavity was tuned to the design frequency, which required frequency changes of 3 kHz to 7 kHz depending on the cavity. Although no piezoelectric actuator is mounted on the tuning system, phase noise caused by microphonics can be sufficiently reduced by a phase-locked loop using a newly developed digital LLRF. The details of the tuning system as well as the digital LLRF will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV013  
About • Received ※ 13 August 2021 — Revised ※ 13 September 2021 — Accepted ※ 11 November 2021 — Issue date ※ 22 November 2021
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WEPTEV015 Design of the 650 MHz High Beta Prototype Cryomodule for PIP-II at Fermilab cryomodule, vacuum, alignment, SRF 671
 
  • V. Roger, S.K. Chandrasekaran, S. Cheban, M. Chen, J. Helsper, J.P. Holzbauer, Y.O. Orlov, V. Poloubotko, B. Squires, N. Tanovic, G. Wu
    Fermilab, Batavia, Illinois, USA
  • N. Bazin, O. Napoly, C. Simon
    CEA-DRF-IRFU, France
  • R. Cubizolles, M. Lacroix
    CEA-IRFU, Gif-sur-Yvette, France
  • M.T.W. Kane
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P. Khare
    RRCAT, Indore (M.P.), India
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Proton Improvement Plan II (PIP-II) is the first U.S. accelerator project that will have significant contributions from international partners. The prototype High Beta 650 MHz cryomodule (pHB650 CM) is designed by an integrated design team, consisting of Fermilab (USA), CEA (France), UKRI-STFC (UK), and RRCAT (India). The manufacturing & assembly of this prototype cryomodule will be done at Fermilab, whereas the production cryomodules will be manufactured and/or assembled by UKRI-STFC, RRCAT, or Fermilab. Similar to the prototype Single Spoke Resonator 1 cryomodule (pSSR1 CM), this cryomodule is based on a strong-back at room temperature supporting the coldmass. The pSSR1 CM led to significant lessons being learnt on the design, procurement, and assembly processes. These lessons were incorporated into the design and processes for the pHB650 CM. Amongst many challenges faced, the main challenges of the pHB650 CM design were to make the cryomodule compatible to overseas transportation and to design components that can be procured in USA, Europe, and India.
 
poster icon Poster WEPTEV015 [0.932 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV015  
About • Received ※ 21 June 2021 — Revised ※ 28 February 2022 — Accepted ※ 20 April 2022 — Issue date ※ 16 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPTEV016 Field Emission Studies During ESS Cryomodule Tests at CEA Saclay cryomodule, electron, simulation, detector 677
 
  • E. Cenni
    CEA-IRFU, Gif-sur-Yvette, France
  • M. Baudrier, G. Devanz, L. Maurice, O. Piquet
    CEA-DRF-IRFU, France
 
  For the development of efficient superconducting cavi-ties, field emission is an important parasitic phenomena to monitor. A diagnostic system composed of Geiger-Mueller (G-M) probes, NaI(Tl) scintillators are placed in the cryomodule test stand. Collected data is analysed and confronted to particle tracking simulation and electro magnetic shower code. With such systematic analysis we aim to identify the most probable field emission location and hence help to improve clean procedures during as-sembly and operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV016  
About • Received ※ 21 June 2021 — Revised ※ 22 September 2021 — Accepted ※ 18 December 2021 — Issue date ※ 17 May 2022
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WEPTEV017 Transportation Analysis of the Fermilab High-Beta 650 MHz Cryomodule cryomodule, vacuum, alignment, acceleration 682
 
  • J. Helsper, S. Cheban
    Fermilab, Batavia, Illinois, USA
  • I. Salehinia
    Northern Illinois University, DeKalb, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy.
The prototype High-Beta 650 MHz cryomodule for the PIP-II project will be the first of its kind to be transported internationally, and the round trip from FNAL to STFC UKRI will use a combination of road and air transit. Transportation of an assembled cryomodule poses a significant technical challenge, as excitation can generate high stresses and cyclic loading. To accurately assess the behavior of the cryomodule, Finite Element Analysis (FEA) was used to analyze all major components. First, all individual components were studied. For the critical/complex components, the analysis was in fine detail. Afterwards, all models were brought to a simplified state (necessary for computational expenses), verified to have the same behavior as their detailed counterparts, and combined to form larger sub-assemblies, with the ultimate analysis including the full cryomodule. We report the criteria for acceptance and methods of analysis, and results for selected components and sub-assemblies.
 
poster icon Poster WEPTEV017 [3.159 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPTEV017  
About • Received ※ 21 June 2021 — Revised ※ 27 December 2021 — Accepted ※ 01 March 2022 — Issue date ※ 02 May 2022
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WEOCAV03 RF Dipole Crab Cavity Testing for HL-LHC HOM, dipole, controls, operation 687
 
  • N. Valverde Alonso, R. Calaga, S.J. Calvo, O. Capatina, O. Capatina, A. Castilla, M. Chiodini, C. Duval, L.M.A. Ferreira, M. Gourragne, P.J. Kohler, T. Mikkola, J.A. Mitchell, E. Montesinos, C. Pasquino, G. Pechaud, N. Stapley, M. Therasse, K. Turaj, J.D. Walker
    CERN, Geneva 23, Switzerland
  • A. Castilla
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A. Castilla
    Lancaster University, Lancaster, United Kingdom
 
  RF Crab Cavities are an essential element of the High Luminosity LHC (HL-LHC) upgrade at CERN. Two RF dipole crab cavity used for the compensation of the horizontal crossing angle were recently manufactured and integrated into Titanium Helium tank and RF ancillaries necessary for the beam operation. The two cavities will be integrated into a cryomodule in collaboration with UK-STFC and tested with proton beams in the SPS in 2023. This paper will highlight the RF measurements during the important manufacturing steps, surface preparation and cavity performance at 2K.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEOCAV03  
About • Received ※ 18 June 2021 — Revised ※ 07 September 2021 — Accepted ※ 16 September 2021 — Issue date ※ 22 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEOCAV04 Optimization of a Traveling Wave Superconducting Radiofrequency Cavity for Upgrading the International Linear Collider ECR, multipactoring, niobium, GUI 694
 
  • V.D. Shemelin
    Valery D Shemelin, Freeville, USA
  • H. Padamsee
    Cornell University, Ithaca, New York, USA
  • H. Padamsee, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  The Standing Wave TESLA Niobium-based structure is limited to a gradient of about 50 MV/m by the critical RF magnetic field. To break through this barrier, we explore the option of Niobium-based traveling wave (TW) structures. Optimization of TW structures was done taking into account experimentally known limiting electric and magnetic fields. It is shown that a TW structure can have an accelerating gradient above 70 MeV/m that is about 1.5 times higher than contemporary standing wave structures with the same critical magnetic field. The other benefit of TW structures shown is R/Q about 2 times higher than TESLA structure that reduces 2 times the dynamic heat load. A method is proposed how to make TW structures multipactor-free. Some design proposals can be realized to facilitate fabrication. Further increase of the real-estate gradient (equivalent to 80 MV/m active gradient) is also possible by increasing the length of the accelerating structure because of higher group velocity and cell-to-cell coupling. Realization of this work opens paths to ILC energy upgrades beyond 1 TeV to 3 TeV in competition with CLIC. The paper will discuss corresponding opportunities and challenges.  
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slides icon Slides WEOCAV04 [3.667 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEOCAV04  
About • Received ※ 15 June 2021 — Accepted ※ 24 October 2021 — Issue date; ※ 16 May 2022  
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WEOCAV06 Saraf-Phase 2 Low-Beta and High-Beta Superconducting Cavities Qualification linac, cryomodule, SRF, MMI 703
 
  • G. Ferrand, G. Jullien, S. Ladegaillerie, N. Misiara, N. Pichoff, C. Servouin
    CEA-IRFU, Gif-sur-Yvette, France
  • M. Baudrier, E. Fayette, L. Maurice
    CEA-DRF-IRFU, France
  • A. Navitski, L. Zweibaeumer
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5 mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL consists in four cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β= 0.09) at 176 MHz. The last two identical cryomodules will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The low-beta prototypes was qualified in 2019. Low-beta series manufacturing is on-going. The high-beta prototype was first tested in 2019 but failed. A new prototype was tested in the end of 2020. This contribution will present the results of the tests for low- and high-beta SARAF cavities, series and prototypes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEOCAV06  
About • Received ※ 21 June 2021 — Revised ※ 17 October 2021 — Accepted ※ 20 December 2021 — Issue date ※ 17 May 2022
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WEOTEV03 Toward Stoichiometric and Low-Surface-Roughness Nb3Sn Thin Films via Direct Electrochemical Deposition SRF, superconductivity, electron, controls 710
 
  • Z. Sun, G. Gaitan, M. Ge, K. Howard, M. Liepe, T.E. Oseroff, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller, J.P. Sethna, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  • K.D. Dobson
    University of Delaware, Newark, Delaware, USA
 
  Reducing surface roughness and attaining stoichiometry of Nb3Sn superconducting films are required to push their superheating field to the theoretical limit in SRF cavities. As such, we explore direct electrochemical processes that minimize involving foreign elements to deposit high-quality Sn, Nb, and NbxSn films on Nb and Cu surfaces. These films are then thermally annealed to Nb3Sn. We find that smooth Sn pre-depositions via electroplating on Nb surfaces significantly reduce the average roughness of resultant Nb3Sn to 65 nm, with a dramatic reduction in power intensity at medium special frequencies. Structural and superconducting properties demonstrate a Nb3Sn A15 phase with a stoichiometry of 25 at% Sn. This process is being scaled-up to a 3.9 GHz cavity. Moreover, preliminary results on electroplating on Cu surface show that Nb plating undergoes a slow growth rate while subsequent Sn plating on the plated Nb surface can be controlled with varied thickness. The Nb plating process is currently being optimized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEOTEV03  
About • Received ※ 09 July 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 16 January 2022
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THOTEV02 Stable Beam Operation in cERL for Medical and Industrial Application at KEK operation, FEL, linac, SRF 714
 
  • H. Sakai, M. Adachi, D.A. Arakawa, S. Eguchi, M.K. Fukuda, K. Haga, M. Hagiwara, K. Hara, K. Harada, N. Higashi, T. Honda, Y. Honda, T. Honma, M. Hosumi, E. Kako, Y. Kamiya, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, T. Konomi, H. Matsumura, S. Michizono, C. Mitsuda, T. Miura, T. Miura, T. Miyajima, Y. Morikawa, S. Nagahashi, H. Nakai, N. Nakamura, K. Nakanishi, K.N. Nigorikawa, T. Nogami, T. Obina, F. Qiu, H. Sagehashi, M. Shimada, H. Shimizu, T. Shioya, M. Tadano, T. Takahashi, R. Takai, H. Takaki, O.A. Tanaka, Y. Tanimoto, A. Toyoda, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
    KEK, Ibaraki, Japan
  • R. Hajima, K. Kawase
    QST, Tokai, Japan
  • N.P. Norvell
    SLAC, Menlo Park, California, USA
  • F. Sakamoto
    Akita National College of Technology, Akita, Japan
  • M. Shimada
    HSRC, Higashi-Hiroshima, Japan
 
  Funding: Supported by Accelerator Inc. and a New Energy and Industrial Technology Development Organization (NEDO) project and JSPS Grant-in-Aid for Scientific Research (KAKENHI) Grant Number JP18H03473.
A superconducting Compact Energy Recovery Linac (cERL) for electrons was constructed in 2013 at KEK to demonstrate energy recovery concept with low emittance, high-current CW beams of more than 10 mA for future multi-GeV ERL. Recently this cERL was operated not only to demonstrate energy recovery linac high current beam operation but also to promote and conduct a variety of industrial applications such as FEL, THz operation and Rare Isotope Production and irradiation for some materials. In this talk, I will present the status of the studies to realize the stable high-current low emittance CW beam and some applications with this beam.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THOTEV02  
About • Received ※ 19 June 2021 — Revised ※ 13 March 2022 — Accepted ※ 13 May 2022 — Issue date ※ 15 May 2022
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THOTEV06 Plasma Electrolytic Polishing as a Promising Treatment Replacement of Electropolishing in the Copper and Niobium Substrate Preparation for SRF plasma, SRF, niobium, cathode 718
 
  • C. Pira, O. Azzolini, R. Caforio, E. Chyhyrynets, V.A. Garcia, G. Keppel, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
 
  Superconducting radio frequency (SRF) cavities performances strongly depend on the substrate preparation. Currently, the conventional protocol of SRF surface preparation includes electropolishing (EP) as the main treatment achieving low roughness, clean and non-contaminated surfaces, both for bulk Nb and Cu substrates. Harsh and non-environmentally friendly solutions are typically used: HF and H2SO4 mixture for Nb, and H3PO4 with Butanol mixtures for EP of Cu. This research is focused on the application of a relatively new technique "Plasma Electrolytic Polishing" (PEP) for the SRF needs. PEP technology is an evolution of EP with a list of advantages that SRF community can benefit from. PEP requires diluted salt solutions moving to a greener approach in respect to EP. PEP can in principle substitute, or completely eliminate, intermediate steps, like mechanical and/or (electro) chemical polishing. Thanks to the superior removing rate in the field (up to 3.5 µm/min of Nb, and 10 µm/min of Cu) in one single treatment roughness below 100 nm Ra has been obtained both for Nb and Cu. In the present work a proof of concept is shown on Nb and Cu planar samples.  
slides icon Slides THOTEV06 [7.197 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THOTEV06  
About • Received ※ 21 June 2021 — Accepted ※ 18 October 2021 — Issue date; ※ 01 May 2022  
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THOTEV07 Industrial X-Ray Tomographie as a Tool for Shape and Integrity Control of SRF Cavities photon, detector, electron, radiation 725
 
  • H.-W. Glock, J. Knobloch, A. Neumann, A.V. Vélez
    HZB, Berlin, Germany
 
  Industrial X-ray tomography offers the possibility to capture the entire inner and outer shape of an SRF cavity, providing also insights in weld quality and material defects. As a non-contact method this is especially attractive to investigate shape properties of fully processed and closed cavities. A drawback is the inherently strong X-ray damping of niobium, which causes the demand for intense hard X-rays, typically beyond the capabilities of dc-X-ray-tubes. This also limits the accuracy of material borders found by the tomographic inversion. To illustrate both capabilities and limitations, results of X-ray tomography investigations using three different cavities are reported, also describing the fundamental parameters and the hard- and software demands of the technology. We also discuss the non-trivial transferring of tomography data into RF simulation tools.  
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slides icon Slides THOTEV07 [9.574 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THOTEV07  
About • Received ※ 30 June 2021 — Revised ※ 03 January 2022 — Accepted ※ 03 March 2022 — Issue date ※ 08 April 2022
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THPFAV002 Fabrication and Installation of Newly Designed Cryostats and Top Flanges for the Vertical Test of RISP SRF, cryogenics, vacuum, cryomodule 733
 
  • M.O. Hyun, M.S. Kim, Y. Kim, J. Lee, M. Lee, J.H. Shin
    IBS, Daejeon, Republic of Korea
  • D.W. Kim, S.R. Kim
    CVE, Suwon, Gyeonggi, Republic of Korea
 
  Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea.
Rare Isotope Science Project (RISP) in the Institute of Basic Science (IBS), South Korea, is now operating SRF test facility in Sindong, Daejeon. Sindong SRF test facility has three vertical test pits and three horizontal test bunkers, 900 W cryogenic system, RF power system, and radiation protection system. This paper explains about detail procedures of constructing cryostats and top flanges for the vertical test of RISP, Installed cryostats and top flanges have insulation vacuum layer, magnetic and thermal shield, 4K/2K reservoir, heat exchanger, cryogenic valves for supplying liquid helium, vacuum lines, and electrical instrumentations for the superconducting cavity tests.
 
poster icon Poster THPFAV002 [2.010 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFAV002  
About • Received ※ 22 June 2021 — Revised ※ 21 August 2021 — Accepted ※ 23 October 2021 — Issue date ※ 22 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPFAV005 LCSL-II Cryomodule Testing at Fermilab cryomodule, LLRF, operation, EPICS 741
 
  • E.R. Harms, B.E. Chase, E. Cullerton, B.D. Hartsell, J. Hurd, M.J. Kucera, F.L. Lewis, A. Lunin, J.N. Makara, D.L. Newhart, D.J. Nicklaus, P.S. Prieto, J. Reid, R.P. Stanek, R. Wang
    Fermilab, Batavia, Illinois, USA
  • A.L. Benwell
    SLAC, Menlo Park, California, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • C.M. Ginsburg
    JLab, Newport News, Virginia, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Cold powered testing of all LCLS-II production cryomodules at Fermilab is complete as of February 2021. A total of twenty-five tests on both 1.3 GHz and 3.9 GHz cryomodules were conducted over a nearly five year time span beginning in the summer of 2016. During the course of this campaign cutting-edge results for cavity Q0 and gradient in continuous wave operation were achieved. A summary of all test results will be presented, with a comparison to established acceptance criteria, as well as overall test stand statistics and lessons learned.
 
poster icon Poster THPFAV005 [1.379 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFAV005  
About • Received ※ 22 June 2021 — Revised ※ 24 November 2021 — Accepted ※ 05 January 2022 — Issue date ※ 01 March 2022
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THPFAV006 Degradation and Recovery of the LHC RF Cryomodule Performance Using the Helium Processing Technique cryomodule, vacuum, radiation, operation 746
 
  • K. Turaj, O. Brunner, A.C. Butterworth, F. Gerigk, P. Maesen, E. Montesinos, F. Peauger, M. Therasse, W. Venturini Delsolaro
    CERN, Meyrin, Switzerland
 
  The LHC RF cryomodule "Asia" suffered an accidental influx of about 0.5 l of tunnel air during the leak checks of the pumping manifolds. The resulting risk of particle contamination was difficult to assess, and could not be excluded with certainty. If one or more cavities were contaminated, a severe impact on beam operations in the LHC machine was to be expected. In order to minimize the risks, the Asia cryomodule has been replaced with a spare unit. Subsequently, the cryomodule was tested in the SM18 test facility without intermediate venting, and showed high levels of radiation due to field emission above 1.8 MV in one of the cavities. The other cavities were less strongly affected, but clear signs of contamination were observed. The helium processing technique was used to improve the performance of the SRF cavity with respect to field emission. This paper will discuss the results of the above-mentioned test.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFAV006  
About • Received ※ 21 June 2021 — Revised ※ 14 January 2022 — Accepted ※ 27 April 2022 — Issue date ※ 01 May 2022
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THPFDV001 Status of the New Quadrupole Resonator for SRF R&D quadrupole, SRF, operation, simulation 751
 
  • R. Monroy-Villa, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Gorgi Zadeh, P. Putek
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • M. Lemke, R. Monroy-Villa, D. Reschke, M. Röhling, J.H. Thie
    DESY, Hamburg, Germany
 
  A basic understanding of the properties of SRF samples under surface treatments would aid in the development of consistent theories. To study the RF properties of such samples under realistic superconducting-cavity-like conditions, a test device called Quadrupole Resonator (QPR) was fabricated. In this publication we report the status of the QPR at Universität Hamburg in collaboration with DESY. Our device is based on the QPRs operated at CERN and at HZB, and its design will allow for testing samples at temperatures between 2 K and 8 K, under magnetic fields up to 120 mT and with operating frequencies of 433 MHz, 866 MHz and 1300 MHz. Fabrication tolerance studies on the electromagnetic field distributions and simulations of the static detuning of the device, together with the commissioning report and the ongoing surface treatment, will be presented.  
poster icon Poster THPFDV001 [1.069 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV001  
About • Received ※ 27 June 2021 — Revised ※ 23 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 29 April 2022
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THPFDV003 SIMS Investigation of Furnace Baked Nb vacuum, niobium, SRF, radio-frequency 761
 
  • E.M. Lechner, M.J. Kelley, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
 
  Funding: U.S. DOE Contract No. DE-AC05-06OR23177
Results recently published by Ito et al. showed that "furnace baking" Nb SRF cavities after electropolishing yields high quality factors and anti-Q-slopes resembling that of N doped cavities. Small Nb samples were prepared following the recipe outlined by Ito. These samples were measured by SIMS to examine impurity contributions to the RF penetration layer. These diffusion profiles are modeled, and their consequences on RF properties discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV003  
About • Received ※ 22 June 2021 — Accepted ※ 24 November 2021 — Issue date; ※ 15 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPFDV005 Superconducting RF Performance of Cornell 500 MHz N-Doped B-Cell SRF Cavitiy SRF, vacuum, cryomodule, GUI 764
 
  • M. Ge, T. Gruber, A.T. Holic, M. Liepe, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Cornell SRF group is working on rebuilding a 500 MHz B-cell cryomodule (CRYO-2 BB1-5) as a spared cryomodule for the operation of the CESR ring. To minimize BCS surface resistance, achieve a high quality-factor (Q0), and increase maximum fields, we prepared the cavity’s surface with electropolishing and performed a 2/6 N2-doping. In this work, we report 4.2 K and 2 K cavity test results with detailed surface resistance analysis, showing improved performance, including significant higher fields.  
poster icon Poster THPFDV005 [0.712 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV005  
About • Received ※ 05 July 2021 — Revised ※ 10 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 22 April 2022
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THPFDV006 Seebeck Coefficient Measurement at Cryogenic Temperatures for the LCLS-II HE Project experiment, cryomodule, niobium, cryogenics 768
 
  • M. Ge, A.T. Holic, M. Liepe, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Reducing thermoelectric currents during cooldown is important to maintain high-quality factors (Q0) of the cavities in the LCLS-II HE cryomodules. The temperature-dependent Seebeck coefficients of the materials used in the cryomodules are needed for quantitative estimations of thermoelectric currents. In this work, we present a setup for cryogenic Seebeck coefficient measurements as well as the measured Seebeck coefficients of high-pure niobium at cryogenic temperatures between 4K and 200K.  
poster icon Poster THPFDV006 [0.505 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV006  
About • Received ※ 29 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 26 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPFDV008 Research on Ceramic for RF Window electron, multipactoring, Windows, operation 771
 
  • Y. Yamamoto, K. Nakamura, H. Yoshizumi
    Kyocera Corporation, Corporate Fine Ceramics Group, Kyoto, Japan
  • S. Michizono, Y. Yamamoto
    KEK, Ibaraki, Japan
 
  Kyocera and KEK had started joint research on developing materials that satisfy the required characteristics as RF window materials. In previous studies, AO479B was developed, and it has been applied to some products. However, AO479B has size limitation in applying to products. Recently, large RF windows is demanded. Therefore, we have developed a new material AO479U which is designed to be applied to products regardless of the product size. In this report, the characteristics of AO479U was evaluated by comparing it with other materials, including the presence or absence of TiN coating. In order to clarify how the differences of materials or manufacturing processes contributes to heat generation and multipactor discharge occurring in RF windows, we measured important characteristics as RF window materials (relative permittivity, dielectric loss tangent, surface resistance, volume resistivity, secondary electron emission coefficient, and TiN thickness), and investigated the relationships of them and materials or manufacturing processes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV008  
About • Received ※ 18 June 2021 — Revised ※ 06 December 2021 — Accepted ※ 28 February 2022 — Issue date ※ 01 May 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPCAV001 Modal Analysis and Vibration Test of Single Spoke Resonator Type-1 (SSR1) for RISP FEM, SRF, simulation, superconductivity 776
 
  • M.O. Hyun, Y.W. Jo, H.C. Jung, Y. Kim, M. Lee
    IBS, Daejeon, Republic of Korea
 
  Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea.
Rare Isotope Science Project (RISP) is developing the single spoke resonator type-1 (SSR1) and type-2 (SSR2) for making superconducting linear accelerator 2 (SCL2). For optimizing of SSR1 and SSR2, we should research every aspects of superconducting cavity including RF performances and mechanical properties. This paper explains about modal analysis of SSR1 using FEM (finite element method) applying material properties of RRR300 niobium for bare cavity and STS316L for liquid helium jacket. Also, this paper shows the vibration test results with modal analysis.
 
poster icon Poster THPCAV001 [1.636 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV001  
About • Received ※ 22 June 2021 — Accepted ※ 06 September 2021 — Issue date; ※ 15 May 2022  
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THPCAV002 Low Temperature Heat Treatment on the HWR Cavity cryomodule, controls, SRF, superconducting-cavity 779
 
  • Y. Jung, H. Jang, H. Kim, H. Kim, J.W. Kim, M.S. Kim, J. Lee, M. Lee
    IBS, Daejeon, Republic of Korea
  • S. Jeon
    Kyungpook National University, Daegu, Republic of Korea
 
  Institute for Basic Science have been constructing Superconducting LINAC composed of quarter wave resonator (QWR) and half wave resonator (HWR). All QWR cavities have been completely fabricated and successfully tested to be assembled in QWR cryomodules. For now, we have been testing HWR cavities over 50%. For the testing period, the success rate experienced up and downs like we went through during the QWR tests. In many cases, we observed that some cavities did not reach requirement performance 2K although they showed high performance at 4K. We increased the temperature of heat treatment to cure the rapid Q drop at the high gradient and observed most cavities passed the test after heat treatment.  
poster icon Poster THPCAV002 [1.975 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV002  
About • Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 22 November 2021 — Issue date ※ 23 February 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPCAV003 Impact of Vertical Electropolishing with Flipping System on Removal Uniformity and Surface State: Study with 9-Cell Niobium Coupon Cavity cathode, experiment, niobium, status 783
 
  • K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki
    KEK, Ibaraki, Japan
 
  We have been developing a vertical electropolishing (VEP) method for niobium superconducting RF cavities using a novel setup that allows periodic flipping of the cavity to put it upside down in the VEP process. The purpose of using the novel setup named as flipping system is to achieve uniform removal and smooth surface of the cavity. Previously, we have already introduced the VEP system and showed the preliminary results of VEP performed with the flipping system. In this article, we report VEP results obtained with a nine-cell coupon cavity. The results include detail on coupon currents with I-V curves for coupons, and impact of the cavity flipping on removal uniformity and surface morphology of the cavity.  
poster icon Poster THPCAV003 [1.261 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV003  
About • Received ※ 19 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 22 October 2021 — Issue date ※ 23 November 2021
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPCAV005 Status of the INFN-LASA Contribution to the PIP-II Linac SRF, linac, simulation, experiment 787
 
  • R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, G. Fornasier, A.T. Grimaldi, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  The international effort for the PIP-II project at Fermilab has been joined by INFN with its planned contribution to the PIP-II proton linac in the low-beta section. INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, 36 plus spares resonators with 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry to reach the unprecedented performances required by PIP-II, qualified through vertical cold test at state-of-the art infrastructures and delivered as ready for the linac at the string assembly site. The status of INFN contribution to PIP-II, the development of infrastructures and prototypes as well as the ongoing activities toward the start of series production are summarized in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV005  
About • Received ※ 21 June 2021 — Accepted ※ 09 October 2021 — Issue date; ※ 08 May 2022  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPCAV006 Recent Activities Regarding 9-Cell TESLA-Type Cavities at KEK EPICS, controls, niobium, superconducting-RF 792
 
  • M. Omet, R. Katayama, K. Umemori
    KEK, Ibaraki, Japan
 
  In this contribution we report on two topics regarding recent activities on 9-cell TESLA-type cavities at the High Energy Accelerator Research Organization (KEK). First, we give an overview of the inner surface treatments and vertical test (VT) results of four fine grain 9-cell TESLA-type cavities over the last one and a half years. Secondly, we report on the upgrade of the VT DAQ system at the Superconducting RF Test Facility (STF) at KEK. In this upgrade, most components of the VT system were integrated in an EPICS control system. Based on Control System Studio (CSS) and Python a new user interface was created, improving the workflow during and after VTs at STF.  
poster icon Poster THPCAV006 [1.748 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV006  
About • Received ※ 18 June 2021 — Revised ※ 26 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 04 March 2022
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THPCAV007 Thermal Mapping Studies on Nb/Su SRF Cavities SRF, interface, experiment, cryogenics 796
 
  • A. Bianchi, M. Chiodini, G. Vandoni, W. Venturini Delsolaro
    CERN, Meyrin, Switzerland
 
  A thermal mapping system is one of the most useful diagnostic tools to identify the mechanisms responsible of performance degradation in superconducting radio frequency (SRF) cavities. Unlike most of the thermal mapping systems currently in operation, we want to develop a system for mapping copper coated SRF cavities. This thermal mapping system, based on contact thermometry, will operate in both superfluid and normal liquid helium for the study of thin film cavities on copper built at CERN. This paper describes the R&D studies to design and develop the system. The characterisation of thermometers and the validation of their thermal contact are presented. Thanks to the use of some heaters with the aim of reproducing the presence of heat losses in a SRF cavity, temperature profiles on a copper surface will be shown at different conditions of the helium bath. In addition, preliminary results on magnetic field sensors, based on the anisotropic magnetoresistance effect, will be reported in view of their possible implementation in the thermal mapping system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV007  
About • Received ※ 18 June 2021 — Revised ※ 23 August 2021 — Accepted ※ 25 November 2021 — Issue date ※ 12 May 2022
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THPCAV008 Results From the Proton Power Upgrade Project Cavity Quality Assurance Plan cryomodule, linac, hardware, operation 801
 
  • J.D. Mammosser, E. Robertson
    ORNL RAD, Oak Ridge, Tennessee, USA
  • R. Afanador, M.S. Champion, M.N. Greenwood, M.P. Howell, S.-H. Kim, S.E. Stewart, D.J. Vandygriff
    ORNL, Oak Ridge, Tennessee, USA
  • A. Bitter, K.B. Bolz, A. Navitski, L. Zweibaeumer
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • E. Daly, G.K. Davis, P. Dhakal, D. Forehand, K. Macha, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  Funding: UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE)
The Proton Power Upgrade (PPU) Project at Oak Ridge National Lab’s Spallation Neutron Source (SNS) is currently under construction. The project will double the beam power from 1.4 to 2.8 MW. This is accomplished by increasing the beam current and adding seven new Superconducting Radio Frequency (SRF) cryomodules. Each new cryomodule will contain four six-cell, beta 0.81, PPU style cavities. A quality assurance plan was developed and implemented for the procurement of 32 PPU cavities. As part of this plan, reference cavities were qualified and sent to Research Instruments Co. for the development and verification of process steps. Here we present the results from this plan to date.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV008  
About • Received ※ 04 June 2021 — Accepted ※ 06 September 2021 — Issue date; ※ 16 May 2022  
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THPCAV009 Statistical Modeling of Peak Accelerating Gradients in LCLS-II and LCLS-II-HE cryomodule, multipactoring, simulation, accelerating-gradient 804
 
  • J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  In this report, we study the vertical test gradient performance and the gradient degradation between vertical test and cryomodule test for the 1.3 GHz LCLS-II cavities. We develop a model of peak gradient statistics, and use our understanding of the LCLS-II results and the changes implemented for LCLS-II-HE to estimate the expected gradient statistics for the new machine. Finally, we lay out a plan to ensure that the LCLS-II-HE cryomodule gradient specifications are met while minimizing cavity disqualification by introducing a variable acceptance threshold for the accelerating gradient.  
poster icon Poster THPCAV009 [1.306 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV009  
About • Received ※ 21 June 2021 — Revised ※ 14 September 2021 — Accepted ※ 02 November 2021 — Issue date ※ 23 November 2021
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THPCAV011 Operational Experience with the Mechanical Tuner Systems in the Superconducting Linac at IUAC controls, linac, operation, resonance 809
 
  • A. Pandey, R. Ahuja, G.K. Chaudhari, B.B. Chaudhary, R.N. Dutt, S. Ghosh, B. Karmakar, J. Karmakar, R. Kumar, D.S. Mathuria, P. Patra, P.N. Potukuchi, A. Rai, B.K. Sahu, S.K. Saini, A. Sharma, S.K. Sonti, S.K. Suman
    IUAC, New Delhi, India
 
  The phase locking of the QWRs by dynamic phase control method in the superconducting linac at IUAC is done in a faster time scale. The slow frequency drifts (few hundreds of ms) are corrected using a niobium bellows tuner attached at the open end of the cavity. Initially, the tuners in the cavities were operated using helium gas. This system had the limitation of non-linearity, hysteresis and slow response due to which the cavities could not be phase locked at higher fields. To address this, piezo based tuning system was implemented in the cavities of the 2nd and 3rd linac modules. But due to space constraints, the same could not be used in the 1st linac module and the buncher modules. For them, the helium gas based system was continued, albeit with suitable modifications. The old flow control valves which operated with DC voltages were replaced with valves operating in pulsed mode and controlled by varying the duty cycle of the input pulses. The above mentioned limitations were overcome by using this PWM based technique and this enabled phase locking at higher gradients. This paper presents our operational experience with all the different tuning systems and their comparison.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV011  
About • Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021
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THPCAV012 ESS Medium Beta Cavities at INFN LASA linac, SRF, multipactoring, operation 815
 
  • D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, A.T. Grimaldi, L. Monaco, R. Paparella, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  INFN Milano - LASA contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. All the cavities have been mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold at DESY. We present the result of the cavities already qualified and delivered to CEA, discussing the lessons learnt so far. For remaining cavities, we discuss the actions taken and the plans foreseen to recover them to full specifications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV012  
About • Received ※ 21 June 2021 — Revised ※ 01 September 2021 — Accepted ※ 10 October 2021 — Issue date ※ 23 November 2021
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THPCAV014 Development of High-Q Treatments for PIP-II Prototype Cavities at LASA-INFN target, SRF, niobium, operation 820
 
  • M. Bertucci, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • A. Gresele, A. Torri
    Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • M. Rizzi
    Ettore Zanon S.p.A., Schio, Italy
 
  INFN-LASA is currently involved in the production of PIP-II low-beta cavity prototypes. The main challenge of this activity is to develop a state-of-the art surface treatment recipe on such cavity geometry, to achieve the high-Q target required for cavity operation in the linac. This paper reports the status of cavity treatments development and the first cold test results of a single-cell cavity. This cavity has undergone a baseline treatment based on Electropolishing as bulk removal step. Being this test successful, a strategy for pushing the cavities towards higher performances is here proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV014  
About • Received ※ 21 June 2021 — Accepted ※ 01 March 2022 — Issue date; ※ 01 May 2022  
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THPTEV002 Enhanced Pneumatic Tuner Control for FRIB Half-Wave Resonators controls, solenoid, feedback, cryomodule 829
 
  • W. Chang, W. Hartung, S.H. Kim, J.T. Popielarski, T. Xu, C. Zhang, S. Zhao
    FRIB, East Lansing, Michigan, USA
 
  The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) includes a total of 46 cryomodules; 31 cryomodules contain half-wave resonators (HWRs) with pneumatic tuners. Pneumatic tuner control is via solenoid valves connecting the tuner to a helium gas supply manifold and a gas return line. For precise compensation of cavity detuning over a small range, the control voltage for the solenoid valves must be calibrated. Some valves have hysteresis in the gas flow rate as a function of control voltage, such that their response may be nonlinear and not repeatable–this makes the control algorithm challenging. To improve the system performance, a new pneumatic tuner control system was developed which regulates the position of one stepper motor instead of the two solenoid valves.  
poster icon Poster THPTEV002 [1.321 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV002  
About • Received ※ 24 June 2021 — Revised ※ 15 December 2021 — Accepted ※ 17 February 2022 — Issue date ※ 16 May 2022
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THPTEV003 LCLS-II Cryomodules Production Experience and Lessons Learned Towards LCLS-II-HE Project cryomodule, controls, SRF, vacuum 832
 
  • T.T. Arkan, D.J. Bice, J.N. Blowers, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, M. Martinello, T.H. Nicol, Y.O. Orlov, S. Posen, K.S. Premo, R.P. Stanek
    Fermilab, Batavia, Illinois, USA
 
  Funding: DOE
LCLS-II is an upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac consists of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF (SRF) continuous wave (CW) cryomodules with high quality factor cavities. Cryomodules were produced at Fermilab and at Jefferson Lab in collaboration with SLAC. Fermilab successfully completed the assembly, testing and delivery of seventeen 1.3 GHz and three 3.9 GHz cryomodules. LCLS-II-HE is a planned upgrade project to LCLS-II. The LCLS-II-HE linac will consist of twenty-three 1.3 GHz cryomodules with high gradient and high quality factor cavities. This paper presents LCLS-II-HE cryomodule production plans, emphasizing the improvements done based on the challenges, mitigations, and lessons learned from LCLS-II.
 
poster icon Poster THPTEV003 [0.615 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV003  
About • Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021
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THPTEV004 Surface Oxides on Nb and Nb3Sn Surfaces: Toward a Deeper Understanding SRF, niobium, superconductivity, electron 836
 
  • Z. Sun, M. Liepe, T.E. Oseroff, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, Z. Baraissov, D.A. Muller, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  • C. Dukes
    University of Virginia, Charlottesville, Virginia, USA
  • D. Johnson-McDaniel, M. Salim
    CCMR, Ithaca, New York, USA
 
  Surface oxides on Nb and Nb3Sn SRF cavities, as a thin ’dirty’ layer, could be critical to their performance as suggested by recent theory. Although these oxides have been studied in the past, we intend here to provide a deeper understanding based on a systematic study on coupon samples that have been processed under the different conditions currently used in SRF cavity treatments. Our aim is to obtain a more complete picture of the oxide evolution. This then might help to explain the observed cavity performance variation, and might allow designing a process to achieve a designed, optimized surface with controlled oxides types and thickness. We find that the surface oxides are in amorphous phase that exhibits normal conducting behaviors, while the pentoxide further degrades with time. Also, we observed a thin hydroxide layer on the outermost surface and possibly Nb(OH)x motifs in the bulk. Moreover, distinctive oxide structures were found in Nb3Sn samples from vapor diffusion, electroplating, and sputtering. The semiconducting SnOx appeared through the oxide depth in vapor diffused Nb3Sn, while a ~1 nm SnOx layer merely exists at the outermost surface of electroplated Nb3Sn.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV004  
About • Received ※ 09 July 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 04 November 2021
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THPTEV006 Design of the PIP-II 650 MHz Low Beta Cryomodule cryomodule, vacuum, SRF, superconductivity 841
 
  • N. Bazin, S. Berry, G. Maitre, O. Napoly, C. Simon
    CEA-DRF-IRFU, France
  • S. Bouaziz, R. Cubizolles, M. Lacroix
    CEA-IRFU, Gif-sur-Yvette, France
  • S.K. Chandrasekaran, Y.O. Orlov, V. Roger
    Fermilab, Batavia, Illinois, USA
 
  The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and is responsible of the 650 MHz low-beta section made of 9 cryomodules, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and the 9 series ones. This paper will present the design of the 650 MHz low-beta cryomodule.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV006  
About • Received ※ 02 July 2021 — Accepted ※ 30 January 2022 — Issue date; ※ 01 May 2022  
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THPTEV008 Development of a Digital LLRF System for SRF Cavities in RAON Accelerator controls, LLRF, SRF, resonance 845
 
  • H. Jang, D.H. Gil, Y. Jung, H. Kim, Y. Kim, M. Lee
    IBS, Daejeon, Republic of Korea
 
  An ion accelerator, RAON is planned and under construction in Daejeon, Korea by Rare Isotope Science Project (RISP) team in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and IF (In-flight Fragmentation) method. To achieve this goal RAON adopted the superconducting cavities at three different frequency (81.25 MHz, 162.5 MHz and 325 MHz) and their RF field will be controlled independently for the acceleration of ions with various A/q. A solid state power amplifier and a low level RF (LLRF) controller pairs are under development to generate and to control the RF for the cavities. Recently the development and evaluation of the digital-based LLRF have been performed. For the operation and test of SRF cavities, self-excited loop (SEL) and generator-driven-resonator (GDR) algorithm is digitally implemented and its test was performed. In this paper the status and test result of RAON LLRF controller will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV008  
About • Received ※ 21 June 2021 — Revised ※ 30 August 2021 — Accepted ※ 26 September 2021 — Issue date ※ 23 November 2021
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THPTEV012 Substitution of Spring Clamps for Bolts on SRF Cavity Flanges to Minimize Particle Generation SRF, vacuum, cryomodule, niobium 853
 
  • G.H. Biallas
    Hyperboloid LLC, Yorktown, Virginia, USA
  • E. Daly, K. Macha, C.E. Reece
    JLab, Newport News, Virginia, USA
 
  Funding: Funding supplied by US Department of Energy SBIR Grant #DE-SC0019579
Hyperboloid LLC developed and successfully tested a System of High Force Spring Clamps to substitute, one for one, for bolts on the flanges of SRF Cavities. The Clamps are like exceptionally forceful binder clips. The System, that includes the Hydraulic Openers that apply the clamps, minimizes generation of particulates when sealing cavity flanges. Hyperboloid LLC used ANSYS to design the titanium clamps that generate the force to seal the hexagonal cross section, relatively hard aluminum gasket developed for TESLA and used at JLab and other accelerators. The System is developed to be suitable for use in SRF Clean Rooms. Results of particle counter readings during bolt and clamp installation and superfluid helium challenges to the sealed flanges are discussed. Results of a half-size clamp that could seal a soft aluminum gasket and the attempt to seal a gasket made of niobium are also discussed.
L. Monaco, P. Michelato, C. Pagani, N. Panzeri, Experimental and Theoretical Analysis of Tesla-like SFRF Cavity Flanges, INFN Milano- LASA, I-20090 Segrate (MI), Italy. Proc. EPAC 2006, Edinburgh, SC
 
poster icon Poster THPTEV012 [1.400 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV012  
About • Received ※ 21 June 2021 — Revised ※ 16 December 2021 — Accepted ※ 28 April 2022 — Issue date ※ 01 May 2022
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THPTEV013 LCLS-II Cryomodule Production at JLab: Summary and Lessons cryomodule, operation, FEL, SRF 858
 
  • N.A. Huque, E. Daly, J.P. Preble, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  Cryomodules for the Linear Coherent Light Source II (LCLS-II) at SLAC National Accelerator Laboratory were jointly fabricated at Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Facility (FNAL). Procurements, cavity testing, cryomodule assembly, and cryomodule testing were carried out at the two labs. Twenty-one 1.3 GHz cryomodules were fabricated at JLab. The LCLS-II cryomodules are based on the design used in the European X-Ray Free Electron Laser (XFEL) but modified for continuous wave operation. The higher performance requirements lead to challenges in cavity processing, microphonics, magnetic hygiene and cryomodule transportation. This paper outlines the cryomodule production experience at JLab, as well as improvements to procedures and infrastructure to overcome the performance challenges of the LCLS-II design.  
poster icon Poster THPTEV013 [2.441 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV013  
About • Received ※ 21 June 2021 — Revised ※ 02 December 2021 — Accepted ※ 24 January 2022 — Issue date ※ 01 May 2022
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THPTEV015 Cylindrical Magnetron Development for Nb3sn Deposition via Magnetron Sputtering SRF, target, site, radio-frequency 868
 
  • Md.N. Sayeed, H. Elsayed-Ali
    ODU, Norfolk, Virginia, USA
  • C. Côté, M.A. Farzad, A. Sarkissian
    PLASMIONIQUE Inc., Varennes, Québec, Canada
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177.
Due to its better superconducting properties (critical temperature Tc~ 18.3 K, superheating field Hsh~ 400 mT), Nb3Sn is considered as a potential alternative to niobium (Tc~ 9.25 K, Hsh~ 200 mT) for superconducting radiofrequency (SRF) cavities for particle acceleration. Magnetron sputtering is an effective method to produce superconducting Nb3Sn films. We deposited superconducting Nb3Sn films on samples with magnetron sputtering using co-sputtering, sequential sputtering, and sputtering from a stoichiometric target. Nb3Sn films produced by magnetron sputtering in our previous experiments have achieved DC superconducting critical temperature up to 17.93 K and RF superconducting transition at 17.2 K. A magnetron sputtering system with two identical cylindrical cathodes that can be used to sputter Nb3Sn films on cavities has been designed and is under development now. We report on the design and the current progress on the development of the system.
 
poster icon Poster THPTEV015 [1.126 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV015  
About • Received ※ 22 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 September 2021
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THPTEV016 The Role of Oxygen Concentration in Enabling High Gradients in Niobium SRF Cavities niobium, SRF, ECR, radio-frequency 871
 
  • D. Bafia, A. Grassellino, A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
 
  We studied the role of O concentration with depth in the performance of Nb SRF cavities. An ensemble of electropolished 1.3 GHz cavities, which initially showed high field Q-slope (HFQS), was subjected to sequential testing and treatment with in-situ low temperature baking at various temperatures. We find that increasing the bake duration causes (i) an increase in the onset of HFQS until it is absent up to quench (ii) a non-monotonic relationship with the quench field (iii) an evolution of the RBCS toward a non-equilibrium behavior that drives anti-Q slope. Our data is qualitatively explained by assuming an O diffusion model and suggests that the mitigation of HFQS that arises from 120°C in-situ LTB is mediated by the diffusion of O from the native oxide which prevents the precipitation of proximity-coupled Nb nano-hydrides, in turn enabling higher quench fields. The decrease in quench field for cavities in which O has been diffused >90 nm from the RF surface may be due to a reduction of the field limit in the SS bilayer structure. We also suggest that the evolution of the RBCS occurs due to the absence of proximity coupled inclusions, bringing about non-equilibrium effects.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV016  
About • Received ※ 22 June 2021 — Revised ※ 13 September 2021 — Accepted ※ 13 October 2021 — Issue date ※ 23 November 2021
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THPTEV017 Status of the LCLS-II HE Project at Jefferson Lab cryomodule, SRF, HOM, vacuum 876
 
  • K.M. Wilson, J. Hogan, M. Laney, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
 
  Funding: This work was supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and for BES under contract DE’AC02’76SF00515 (SLAC).
The Linac Coherent Light Source II High Energy (LCLS-II-HE) upgrade at the SLAC National Accelerator Laboratory is being constructed in partnership with the Thomas Jefferson National Accelerator Facility (JLab) and the Fermi National Accelerator Laboratory (FNAL). The cryomodule production scope consists of the design, procurement, construction, and acceptance testing of 24 eight-cavity, 1.3 GHz cryomodules, as well as R&D activities necessary to develop the required technology. To achieve this, JLab and FNAL are also contributing to SLAC’s effort to develop the cavity recipe and production processes necessary to meet the LCLS-II-HE goal of 20.8 MV/m and average Q0 of 2.7·1010. This paper details the JLab scope, focusing on the project initiation phase, in particular technology development and prototyping, project development and planning, and implementation of lessons learned from LCLS-II.
 
poster icon Poster THPTEV017 [1.531 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPTEV017  
About • Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 02 March 2022 — Issue date ※ 01 May 2022
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FROFDV01 Systematic Investigation of Mid-T Furnace Baking for High-Q Performance niobium, vacuum, SRF, superconducting-RF 881
 
  • H. Ito, A. Araki, K. Umemori
    KEK, Ibaraki, Japan
  • K. Takahashi
    Sokendai, Ibaraki, Japan
 
  We report on an investigation of the effect of a new baking process called "furnace baking" on the quality factor. Furnace baking is performed as the final step of the cavity surface treatment; the cavities are heated in a vacuum furnace in a temperature range of 200-800C for 3 h, followed by high-pressure rinsing and radio-frequency measurement. We find the anti-Q-slope for cavities furnace-baked at a temperature range of 250 to 400C and a reduction in the residual resistance for all cavities. In particular, an extremely high Q value of 5·1010 at 16 MV/m and 2.0 K is obtained for cavities furnace-baked at 300C.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-FROFDV01  
About • Received ※ 21 June 2021 — Accepted ※ 24 February 2022 — Issue date; ※ 30 April 2022  
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FROFDV03 Investigating the Anomalous Frequency Variations Near Tc of Nb SRF Cavities niobium, SRF, ECR, scattering 885
 
  • D. Bafia, M. Checchin, A. Grassellino, A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
  • J. Zasadzinski
    IIT, Chicago, Illinois, USA
 
  We report recent studies on the anomalous frequency variations of 1.3 GHz Nb SRF cavities near the transition temperature Tc and use them to investigate the underlying physics of state-of-the-art surface treatments. One such feature, a dip in frequency, correlates directly with the quality factor at 16 MV/m and the anti-Q slope that arise in cavities with dilute concentrations of N interstitial in the RF layer achieved via N-doping and mid temperature baking. For N interstitial, we find that the dip magnitude and Tc follow exponential relationships with the electronic mean free path. We present the first observation of the frequency dip near Tc in a cavity baked at 200 C in-situ for 11 hours, which is concurrent with the anti-Q slope, and may be driven by oxygen diffused from the native oxide, thus suggesting the possibility of ‘‘O-doping.’’ We also investigate the conductivities of two cavities that display different resonant frequency behaviors near Tc and suggest that the anti-Q slope and frequency dip phenomena may occur in the presence of interstitial N or possibly O that inhibit the formation of proximity coupled Nb nano-hydrides.  
slides icon Slides FROFDV03 [1.035 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-FROFDV03  
About • Received ※ 25 June 2021 — Revised ※ 13 September 2021 — Accepted ※ 18 December 2021 — Issue date ※ 28 April 2022
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FROFDV06 Synthesis of Nb and Alternative Superconducting Film to Nb for SRF Cavity as Single Layer site, SRF, niobium, target 893
 
  • R. Valizadeh, P. Goudket, A.N. Hannah, O.B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C.Z. Antoine
    CEA-DRF-IRFU, France
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • E. Chyhyrynets, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • P. Goudket, O.B. Malyshev, D.J. Seal, B.S. Sian, D.A. Turner
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • S.B. Leith, A.O. Sezgin, M. Vogel
    University Siegen, Siegen, Germany
  • A. Medvids, P. Onufrijevs
    Riga Technical University, Riga, Latvia
  • D.J. Seal, B.S. Sian, D.A. Turner
    Lancaster University, Lancaster, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • A. Sublet, G. Vandoni, L. Vega Cid, W. Venturini Delsolaro, P. Vidal Garcia
    CERN, Meyrin, Switzerland
 
  "Bulk niobium (Nb) has been the material of choice for superconducting RF (SRF) cavities but for further improvement in cavity RF performance, one may have to turn to films of Nb and to other superconducting materials deposited on copper as thermal and mechanical support. Other materials known as A15, such as Nb3Sn or V3Si and B1 such as NbTiN and NbN are much easier to synthesise in thin films rather than being made as bulk cavity. The potential benefits of using materials other than Nb would be a higher Tc, a potentially higher critical held Hc, leading to potentially significant cryogenics cost reduction if the cavity operation temperature is 4.2 K or higher. We report on optimising deposition parameters and effect of substrate treatment prior to deposition for successful synthesising of Nb and the alternative superconducting thin film with high superconducting properties (Tc and Hsh) on flat substrates and QPR samples in single layer. The DC and RF SC properties have been tested using PPMS and QPR measurements. This work is part of the H2020 ARIES collaboration. We further report on preparation of RF cavities employing these alternative material for future cavity production."  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-FROFDV06  
About • Received ※ 21 June 2021 — Accepted ※ 05 January 2022 — Issue date; ※ 28 April 2022  
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