Author: Yamaguchi, T.Y.
Paper Title Page
MOPLR037 Study of the Surface and Performance of Single-Cell Nb Cavities After Vertical EP Using Ninja Cathodes 217
 
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • P. Carbonnier, F. Éozénou, Y. Gasser, L. Maurice, C. Servouin
    CEA/DSM/IRFU, France
  • F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • K. Ishimi
    MGI, Chiba, Japan
 
  A 1.3 GHz single-cell niobium (Nb) coupon cavity was vertically electropolished (VEPed) with three different Ninja cathodes which were specially designed for VEP of 1.3 GHz superconducting RF elliptical (ILC/Tesla type) cavities. The cathodes were fabricated to have different surface areas and different distances between cathode surface and the equator. The Ninja cathode prepared with an enhanced cathode surface area was covered with a meshed shield to avoid bubble attack on the surface of the cavity cell. It has been turned out that the anode-cathode distance and the cathode area affect surface morphology of the equator. A smooth equator surface was obtained in the cases in which the cathode surface was geometrically close to the equator or instead the cathode surface area was sufficiently larger. Two 1.3 GHz ILC/Tesla type single-cell cavities VEPed with the Ninja cathodes and using optimized conditions showed good performance in vertical tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR037  
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MOPLR038 Fabrication of 9 Cell Coupon Cavity for Vertical Electropolishing Test 220
 
  • S. Kato, H. Hayano, H. Inoue, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
 
  We have been using single cell coupon cavities to establish vertical electropolishing (VEP) process for a couple of years. A series of in-situ measurements of an EP current at an individual coupon in a coupon cavity can help determination of appropriate EP conditions. VEPed coupons which are surface analysed with XPS, SEM and the other tools can also bring lot information and expertise to development of VEP cathode and optimization of VEP conditions. This time we fabricated the world first 9-cell coupon cavity where 3 sample coupons at the equators and 6 sample coupons at positions close to the irises can be installed. VEP of this coupon cavity with a newly developed Ninja cathode brought useful information for improvement of the VEP facility and optimization of the VEP conditions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR038  
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MOPLR039 Development of New Type "Ninja" Cathode for Nb 9-cell Cavity and Experiment of Vertical Electro-Polishing 223
 
  • K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • K. Ishimi
    MGI, Chiba, Japan
 
  Marui Galvanizing Co. Ltd. has been improving Vertical Electro-Polishing (VEP) technologies and facilities for Nb 9-cell superconducting accelerator cavity for International Linear Collider (ILC) in collaboration with KEK. This time, we developed new type 'Ninja' cathode in order to improve VEP uniformity of Nb 9-cell cavity inner surface based on the results of 1-cell cavity VEP experiment. In this article, we will report construction of new type "Ninja" cathode for Nb 9-cell cavity and experiment of VEP using this.  
poster icon Poster MOPLR039 [0.610 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR039  
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