SUPCAV —  Sunday Student Poster Cavities   (27-Jun-21   08:00—09:30)
Paper Title Page
SUPCAV002 Ex-Situ Investigation of the Effects of Heating Rate on the Recrystallization in Rolled Polycrystals of High-Purity Niobium 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 ※ doi: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 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 ※ doi: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 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 [0.943 MB]  
DOI • reference for this paper ※ doi: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 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.
 
poster icon Poster SUPCAV006 [1.495 MB]  
DOI • reference for this paper ※ doi: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 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.
 
poster icon Poster SUPCAV007 [1.012 MB]  
DOI • reference for this paper ※ doi: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 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.  
poster icon Poster SUPCAV008 [0.986 MB]  
DOI • reference for this paper ※ doi: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 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 [1.481 MB]  
DOI • reference for this paper ※ doi: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 32
 
  • N. Yuan, L. Lu, W. Ma
    Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
  • G.M. 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 ※ doi: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 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 ※ doi:10.18429/JACoW-SRF2021-SUPCAV011  
About • Received ※ 20 June 2021 — Accepted ※ 15 November 2021 — Issue date ※ 21 March 2022  
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SUPCAV013 Multipacting Analysis of the Quadripolar Resonator (QPR) at HZB 42
 
  • S. Bira, D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • Y. Kalboussi
    CEA-IRFU, Gif-sur-Yvette, France
  • S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • Th. Proslier
    CEA-DRF-IRFU, France
 
  Multipacting (MP) is a resonating electron discharge, often plaguing radio-frequency (RF) structures, produced by the synchronization of emitted electrons with the RF fields and the electron multiplication at the impact point with the surface structure. The electron multiplication can take place only if the secondary emission yield (SEY, i.e. the number of electrons emitted due to the impact of one incoming electron), , is higher than 1. The SEY value depends strongly on the material and the surface contamination. Multipacting simulations are crucial in high-frenquency (HF) vacuum structures to localize and potentially improve the geometry. In this work, multipacting simulations were carried out on the geometry of the Quadrupole Resonator (QPR) in operation at HZB using the Spark 3D module in Microwave Studio suite (CST). These simulations helped to understand a particular behavior observed during the QPR tests, and furthermore made it possible to suggest enhancement ways in order to limit this phenomenon and facilitate its operation.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV013  
About • Received ※ 09 July 2021 — Revised ※ 09 July 2021 — Accepted ※ 09 April 2022 — Issue date ※ 07 May 2022
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SUPCAV014 Design and Simulation of 500 MHz Single Cell Superconducting Cavity 46
 
  • Y.B. Sun, W. Ma
    Sun Yat-sen University, Zhuhai, Guangdong, People’s Republic of China
  • G.M. 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.
 
poster icon Poster SUPCAV014 [0.425 MB]  
DOI • reference for this paper ※ doi: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 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.  
poster icon Poster SUPCAV016 [2.452 MB]  
DOI • reference for this paper ※ doi: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 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 ※ doi: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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