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Shobuda, Y.

Paper Title Page
TUBX01 Impedance and radiation generated by a ceramic chamber with RF shields and TiN coating 125
 
  • Y. H. Chin, S. Lee, K. Takata, T. Toyama
    KEK, Ibaraki
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Tsutsui
    SHI, Tokyo
 
  In the RCS (Rapid Cycle Synchrotron) ring of J-PARC, we use ceramic chambers with the interior TiN coating and exterior Cu RF shields in the magnet sections. A new theory has been developed for calculation of impedance in this unusual configuration. When it was applied to a prototype RCS ceramic chamber, the calculation results got good agreement with the measurement results. We also considered the dipole radiation from gaps between Cu shields of the ceramic chamber in the bending magnets. The effects turn out to be rather small thanks to the special configuration of the ceramic chambers. We measured the radiation from a ceramic break with and without RF shields and capacitors in the KEK, PS and found that the RF shields with capacitors considerably suppress the radiation from the ceramic break. We summarize all these studies in this paper.  
TUBX03 Coupling impedance of the J-PARC kicker magnets 140
 
  • T. Toyama, Y. Hashimoto, E. Nakamura, Y. Shirakabe
    KEK, Ibaraki
  • J. Kamiya, Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
  The single- and twin-wire measurements both for the longitudinal ( ZL ) and transverse impedances ( ZT ) will be discussed for the J-PARC kicker magnets: a lumped circuit kicker and several types of traveling wave kickers. The question if a position shifted single-wire can measure ZT is discussed. The measurement results are compared with the equivalent circuit analysis. The relation between the imaginary part of the impedance and causality will also be discussed.