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Takatomi, T. T.

Paper Title Page
WEPP084 Fabrication of a Quadrant-type Accelerator Structure for CLIC 2716
 
  • T. Higo, Y. Higashi, H. Kawamata, T. T. Takatomi, K. Ueno, Y. Watanabe, K. Yokoyama
    KEK, Ibaraki
  • A. Grudiev, G. Riddone, M. Taborelli, W. Wuensch, R. Zennaro
    CERN, Geneva
 
  In order to heavily damp the higher order modes of an accelerator structure for CLIC, two kind of damping mechanisms are implemented in one of the designs. Here each cell is equipped with electrically coupled damping channels in addition to the magnetically coupled waveguides. This design requires an assembly of longitudinally cut four quadrants to form a structure and the parts are necessarily made with milling. Since KEK has developed a high-precision machining of X-band accelerator cells with milling and turning at the same time, the experience was extended to the milling of this quadrant. Firstly, the fabrication test of a short quadrant was performed with multiple vendors to taste the present-day engineering level of milling. Following this, a full-size quadrant is also made. In this course, some of the key features are addressed, such as flatness of the reference mating surfaces, alignment grooves, 3D profile shape of the cells, surface roughness and edge treatment. In this paper, these issues are discussed from both fabrication and evaluation point of views.  
MOPP074 Improvement of an S-band RF-gun cavity with a Cs-Te Photo-cathode 721
 
  • A. Murata, Y. Hama, T. Hirose, Y. Kato, K. Sakaue, T. Suzuki, M. Washio
    RISE, Tokyo
  • H. Hayano, N. Kudoh, T. T. Takatomi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • Y. Kamiya
    University of Tokyo, Tokyo
  • S. Kashiwagi
    ISIR, Osaka
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
 
  A 1.6cell S-band photo-cathode RF-Gun is one of the good alternatives of the short pulse electron source. Therefore,we are operating as a high brightness short pulse electron source for studying a reaction of radiation chemistry,an inverse Compton scattering at Waseda University and as an injector at KEK-ATF. To improve an electron beam quality and to reduce a dark current,we decided to improve the RF-Gun cavity. Frequency tuning of the half cell of existing RF-gun was performed by the torque control of Helicoflex seal on the cathode plate and two moving rod type tuners were installed on the full cell. Newly designed RF-Gun cavity has four compact tuners on each cell,which can be tune the frequency to deform the cavity wall,to remove the Helicoflex seal and tuning holes that were considered to be the major cause of electric discharge and/or a dark current source. According to these improvements,the Q-value and shunt impedance of the cavity is 30% larger than that of existing guns. As the result,the reduction of dark current is succeeded and the beam energy is reached up to 5.5MeV at 10MW RF input. The detailed results of electron beam generation will be reported at the conference.