Author: Yamamoto, Y.
Paper Title Page
TUPFAV003 Stable Beam Operation at 33 MV/m in STF-2 Cryomodules at KEK 382
  • Y. Yamamoto, M. Akemoto, D.A. Arakawa, A. Araki, S. Araki, A. Aryshev, T. Dohmae, M. Egi, M.K. Fukuda, K. Hara, H. Hayano, Y. Honda, T. Honma, H. Ito, E. Kako, H. Katagiri, R. Katayama, M. Kawamura, N. Kimura, Y. Kojima, Y. Kondou, T. Konomi, M. Masuzawa, T. Matsumoto, S. Michizono, Y. Morikawa, H. Nakai, H. Nakajima, K. Nakanishi, M. Omet, T. Oyama, T. Saeki, H. Sakai, H. Shimizu, S.I. Takahara, R. Ueki, K. Umemori, A. Yamamoto
    KEK, Ibaraki, Japan
  • S. Aramoto
    Hiroshima University, Higashi-Hiroshima, Japan
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  • Z.J. Liptak
    HU/AdSM, Higashi-Hiroshima, Japan
  • K. Sakaue
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  • A. Yamamoto
    CERN, Meyrin, Switzerland
  In STF at KEK, as the operational demonstration of the SRF accelerator for ILC, the STF-2 cryomodules (CM1+CM2a: one and half size CM with 12 cavities) have achieved 33 MV/m as average accelerating gradient with 7 cavities in Mar/2019. After that, one cavity with the lowest performance installed in CM2a was replaced with one N-infused cavity developed for High-Q/High-G R&D between Japan and US. From this April, the beam operation started again and those CMs achieved 33 MV/m as average accelerating gradient with 9 cavities including one N-infused cavity again. This is the very important milestone for ILC. In this report, the detailed results will be presented.  
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About • Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 01 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 ※  
About • Received ※ 18 June 2021 — Revised ※ 06 December 2021 — Accepted ※ 28 February 2022 — Issue date ※ 01 May 2022
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