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Higashi, Y.

Paper Title Page
TUPMN050 Development of Pulsed-Laser Super-Cavity for Compact X-Ray Source Based on Laser-Compton Scattering 1034
  • K. Sakaue, M. Washio
    RISE, Tokyo
  • S. Araki, M. K. Fukuda, Y. Higashi, Y. Honda, T. Taniguchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • N. Sasao, H. Yokoyama
    Kyoto University, Kyoto
  • M. Takano
    Tsukuba-shi, Ibaraki-ken
  A compact and high quality x-ray source is required from various field, such as medical diagnosis, drug manifacturing and biological sciences. Laser-Compton based x-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of compact x-ray source. Pulsed-laser super-cavity has been developed for a compact high brightness x-ray sources at KEK-ATF. The pulsed-laser super-cavity increases the laser power and stably makes small laser beam size at the collision point with the electron beam. Recently, 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with 1'000 enhancement in our R&D. Therefore, we have planned a compact hard x-ray sources using 50MeV multi-bunch electrons and a pulse stacking technology with 42cm Fabry-Perot cavity. (LUCX Project at KEK) The photon flux is multiplied with the number of bunches by using multi-bunch beam and super-cavity. Development of the super-cavity and present result of LUCX will be presented at the conference.  
WEPMN026 Test Operation of Ball-Screw-Type Tuner for Low-Loss High-Gradient Superconducting Cavity in a Cryomodule 2104
  • T. Higo, F. Furuta, Y. Higashi, T. Saeki, K. Saito, M. Satoh, H. Yamaoka
    KEK, Ibaraki
  We are constructing a Superconducting RF Test Facility (STF) at KEK as an R&D for ILC accelerator. In STF, four Low-Loss (LL) type 9-cell cavities will be installed into a cryomodule. We are developing ball-screw-type tuner for these cavities aiming at the accelerating gradient of 45 MV/m. At the end of 2006, we installed one LL 9-cell cavity dressed with the ball-screw tuner into the cryomodule. It will be operated without beam in 2007. This paper describes the results of the first operation of the ball-screw tuner for LL 9-cell cavity in the cryomodule of STF.  
WEPMN036 High Field Performance in Reduced Cross-sectional X-Band Waveguides Made of Different Materials 2119
  • K. Yokoyama, Y. Higashi, T. Higo, N. K. Kudo, S. Ohsawa
    KEK, Ibaraki
  To study the characteristics of different materials on high-field rf breakdown we designed a simplified waveguide, where the field of 200MV/m is realized at rf power of 100MW. The geometry is transformed from the WR90, where the height and the width are reduced from 10.16 mm to 1mm and from 22.86mm to 14mm, respectively. This paper reports on the high-gradient testing of copper and stainless-steel waveguides. We have observed rf breakdowns by bursts of x-rays, flashes of visible lights and acoustic signals. Frequent breakdowns are observed at about 100MV/m level in copper case and the study on the stainless-steel waveguide will be performed to be compared to that of copper case.  
WEPMS039 High Power Tests of Normal Conducting Single-Cell Structures 2430
  • V. A. Dolgashev, C. D. Nantista, S. G. Tantawi
    SLAC, Menlo Park, California
  • Y. Higashi, T. Higo
    KEK, Ibaraki
  Funding: This work was supported by the U. S. Department of Energy contract DE-AC02-76SF00515.

We report results of the first high power tests of single-cell traveling-wave and standing-wave accelerating structures. These tests are part of an experimental and theoretical study of RF breakdown in normal conducting structures at 11.4 GHz*. The goal of this study is to determine the gradient potential of normal conducting, RF powered particle beam accelerators. The test setup consists of reusable mode converters and short test structures powered by SLAC?s XL-4 klystron. This setup was created for economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. The mode launchers and structures were manufactured at SLAC and KEK and tested in the klystron test laboratory at SLAC.

* V. A. Dolgashev et al., "RF Breakdown In Normal Conducting Single-Cell Structures," SLAC-PUB-11707, Particle Accelerator Conference (PAC 05), Knoxville, Tennessee, 16-20 May 2005, pp. 595- 599.