THPFDV —  Thursday Poster Fundamental Development and Research   (01-Jul-21   11:10—12:10)
Paper Title Page
THPFDV001 Status of the New Quadrupole Resonator for SRF R&D 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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THPFDV002 The Influence of Irradiation on the Current Carrying Phenomena in HTc Multilayered Superconductors 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
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THPFDV003 SIMS Investigation of Furnace Baked Nb 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  
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THPFDV005 Superconducting RF Performance of Cornell 500 MHz N-Doped B-Cell SRF Cavitiy 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 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
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THPFDV008 Research on Ceramic for RF Window 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
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