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SUPCAV009 First Nb3Sn Coating and Cavity Performance Result at KEK cavity, SRF, radio-frequency, experiment 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.  
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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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TUPFAV002 Calibration of SRF Cavity Voltage by Measurement of Synchrotron Frequency in SuperKEKB cavity, 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 ※ doi: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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TUPCAV010 Application of the ASME Boiler and Pressure Vessel Code in the Design of SRF Cavities at Fermilab cavity, SRF, GUI, niobium 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 ※ doi:10.18429/JACoW-SRF2021-TUPCAV010  
About • Received ※ 22 June 2021 — Accepted ※ 23 August 2021 — Issue date ※ 12 December 2021  
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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 ※ doi:10.18429/JACoW-SRF2021-TUPTEV013  
About • Received ※ 21 June 2021 — Revised ※ 09 October 2021 — Accepted ※ 15 December 2021 — Issue date ※ 22 February 2022
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