Keyword: superconductivity
Paper Title Other Keywords Page
SUPCAV007 Thick Film Morphology and SC Characterizations of 6 GHz Nb/Cu Cavities cavity, niobium, SRF, 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.
 
poster icon Poster SUPCAV007 [1.007 MB]  
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPFDV001 Update on Nitrogen Infusion Sample R&D at DESY niobium, vacuum, cavity, 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  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPFDV006 Investigation of SIS Multilayer Films at HZB SRF, cavity, 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.
 
poster icon Poster SUPFDV006 [2.229 MB]  
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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV003 Cu/Nb QPR Surface Preparation Protocol in the Framework of ARIES Project SRF, cavity, 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 cavity, SRF, MMI, 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
SUPTEV011 Nb3Sn Coating of Twin Axis Cavity for SRF Applications cavity, linac, SRF, niobium 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPCAV009 A New Process for Nitrogen Doping of Niobium Cavities cavity, niobium, SRF, 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
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, cavity, SRF, cryogenics 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)  
 
MOPFDV009 On the Nature of Surface Defects Found in 2/0 N-Doped 9-Cell Cavities cavity, SRF, survey, electron 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPFDV001 Effect of Heating Rate on Recrystallization in Rolled Multicrystals of Pure Niobium ECR, niobium, cavity, SRF 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPFDV008 Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University cavity, SRF, experiment, 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPCAV003 1.3 GHz Seamless Copper Cavities via CNC Spinning Technique cavity, SRF, ECR, 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPTEV003 Progress of MgB2 Deposition Technique for SRF Cavities at LANL cavity, SRF, experiment, 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)  
 
TUPTEV013 Managing Sn-Supply to Tune Surface Characteristics of Vapor-Diffusion Coating of Nb3Sn cavity, SRF, experiment, niobium 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)  
 
WEPTEV012 Characterization of Atomic-Layer-Deposited NbTiN and NbTiN/AlN Films for SIS Multilayer Structures interface, SRF, cavity, site 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)  
 
WEOTEV03 Toward Stoichiometric and Low-Surface-Roughness Nb3Sn Thin Films via Direct Electrochemical Deposition cavity, SRF, 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPFDV002 The Influence of Irradiation on the Current Carrying Phenomena in HTc Multilayered Superconductors induction, radiation, ECR, lattice 756
 
  • J. Sosnowski
    NCBJ, Świerk/Otwock, Poland
 
  Paper is devoted to analysis of the influence of irradiation arising in SRF accelerators on critical current phenomena of HTc multilayered superconductors. Impact of size and concentration of created then nano-defects on current-voltage characteristics and critical current of HTc superconductors as function of the magnetic field and temperature will be investigated. It will be studied basing on analysis of interaction of the magnetic pancake vortices with arising during irradiation defects, for various strengths of capturing. The comparison of the model with experimental data will be given too. The dynamic losses dependent on critical current, generated in the superconducting current leads for varying current, will be considered. Analysis of the dynamic magnetic induction distribution inside superconducting lead for time varying current in the cycle will be given and Joule losses estimated. As the result it has been established the hysteresis behavior of the losses in current leads. The changes of losses have been observed for first and following current increase, which effect should have meaning during multiply charging of the superconducting electromagnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPFDV002  
About • Received ※ 16 June 2021 — Revised ※ 10 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 02 March 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 cavity, FEM, SRF, simulation 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  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPTEV004 Surface Oxides on Nb and Nb3Sn Surfaces: Toward a Deeper Understanding SRF, cavity, niobium, 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
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPTEV006 Design of the PIP-II 650 MHz Low Beta Cryomodule cryomodule, cavity, vacuum, SRF 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  
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)