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Saeki, T.

Paper Title Page
TUP025 Optimization of Surface Treatment of High-Gradient Single-Cell Superconducting Cavities at KEK 299
 
  • F. Furuta, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, T. Saeki, K. Saito, M. Satoh, K. Ueno, H. Yamaoka
    KEK, Ibaraki
  
  We have continued the study of a series of single cell superconducting cavities at KEK. These tests are aimed at establishing a prescription for a surface treatment that would reliably allow cavities to reach gradients in excess of 45 MV/m in vertical tests. The cavity profiles were all of the KEK Low Loss design, and were fabricated from deep drawn Niobium half shells using electron beam welding. The cavity initial surface preparation followed an established KEK procedure of centrifugal barrel polishing, high temperature annealing, light chemical polishing, electropolishing. and final a high pressure water rinse. Early results from this series test demonstrated that reaching gradients as high as 50 MV/m is feasible. However, the initial yield was of order 50%. In this paper we will discuss our studies of further improvement of the surface treatment aimed at increasing the yield.  
THP026 HIGH POWER TEST OF COUPLER WITH CAPACITIVE WINDOW 625
 
  • S. Kazakov, F. Furuta, T. Higo, J. H. Hong, H. Matsumoto, T. Saeki, K. Saito, M. Satoh
    KEK, Ibaraki
  • R. S. Orr
    University of Toronto, Toronto, Ontario
  • H. Urakata
    TETD, Otawara
  • Y. Yano
    Toshiba, Yokohama
  • O. Yushiro
    Toshiba Electron Tubes & Devices Co., Ltd, Tokyo
  
  New type of coupler with capacitive-coupling inner conductor is designed in KEK. This coupler has a module structure, which is convenient for mass-production, assembling and repairing. Four samples of couplers were made and two of them were tested at high power level. The main parameters of the couplers and test results are presented in this paper.  
THP090 Initial Studies of 9-Cell High-Gradient Superconducting Cavities at KEK 794
 
  • T. Saeki, F. Furuta, H. Hayano, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, K. Saito, M. Satoh, N. Toge, K. Ueno, H. Yamaoka, K. Yokoya
    KEK, Ibaraki
  
  Vertical tests of single cell cavities of the KEK Low Loss "Ichiro" design have established that gradients as high as 51 MV/m are feasible in principle. We have also performed vertical tests of 9-cell cavities. The internal surface was prepared according to the prescription developed in the single cell series test. In this paper we report results on the accelerating gradients achieved so far, an investigation of the possible presence of hydrogen "Q Disease," and other high-field related studies. We also present the measurement of the higher modes of the cavities.