Author: Dohmae, T.
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WEPMB012 Production and Investigation of Superconducting 9-Cell Cavity Made of Large Grain Nb in KEK 2141
  • T. Dohmae, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka
    KEK, Ibaraki, Japan
  For CW operation of superconducting cavity, reduction of heat load at cavity surface is one of important topics, since generated heat load is much higher than that of pulse wave. Using Large Grain (LG) Nb for superconducting cavity has possibility to reach higher Q0 than using Fine Grain Nb, which reduces heat load to 2K Helium. KEK Cavity Fabrication Facility(CFF) group had successfully produced superconducting 1-cell cavity made of LG Nb in 2013, and reached high Q0 at the vertical test (maximum field of 45 MV/m). Then, KEK CFF group started producing first superconducting 9-cell LG cavity in 2015, which will be completed in the end of December 2015. Whole processes of producing this cavity from sliced Nb are done in KEK. In this report, process flow and strategies of producing 9-cell cavity and results of vertical test will be presented in detail.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB012  
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WEPMB023 Hydroforming SRF Three-cell Cavity from Seamless Niobium Tube 2170
  • M. Yamanaka, T. Dohmae, H. Inoue, G.-T. Park, K. Umemori
    KEK, Ibaraki, Japan
  • A. Hocker
    Fermilab, Batavia, Illinois, USA
  • T. Tajima
    LANL, Los Alamos, New Mexico, USA
  We are developing the manufacturing method for superconducting radio frequency (SRF) cavities by using a hydroforming instead of using conventional electron beam welding. We expect higher reliability and reduced cost with hydroforming. For successful hydroforming, high-purity seamless niobium tubes with good formability as well as advancing the hydroforming technique are necessary. Using a seamless niobium tube from ATI Wah Chang, we were able to successfully hydroform a 1.3 GHz three-cell TESLA-like cavity and obtained an Eacc of 32 MV/m. A barrel polishing process was omitted after the hydroforming. The vertical test was carried out with very rough inside surface. We got amazing and interesting result.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB023  
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