• J.Y. Zhai, J.P. Dai, L. Dong, J. Gao, Z.D. Guo, Z.Q. Li, L.L. Men, Q.Y. Wang
  IHEP Beijing, Beijing
• J.Z. Chen, J.Q. Qiao
  HJL, Beijing
• J.X. Wang, H. Yu, H. Yuan
  BIAM, Beijing
• W.P. Xie
  Ningxia Orient Tantalum Industry Co., Ltd., Dawukou District, Shizuishan city
• T.X. Zhao
  IHEP Beiing, Beijing

The combination of the low-loss shape and large grain niobium material is expected to be the possible way to achieve higher gradient and lower cost for ILC 9-cell cavities. As the key component of the 'IHEP 1.3 GHz SRF Accelerating Unit and Horizontal Test Stand Project', a low-loss shape 9-cell cavity using Ningxia large grain niobium has been fabricated and surface treated at IHEP and will be tested at KEK. The fabrication procedure, surface treatment recipes as well as the SRF facilities are presented in this paper.

• M. Akemoto, S. Fukuda, H. Honma, H. Nakajima, T. Shidara
  KEK, Ibaraki

This paper describes a long-pulse 1.3 GHz klystron modulator that was recently developed for the Superconducting RF Test Facility (STF) at High Energy Accelerator Research Organization (KEK). The modulators is a direct-switched-type design with a 1:15 step-up transformer and a bouncer circuit to compensate for the output pulse droop within ±0.5%; it can drive a klystron with up to 10 MW peak power, 1.5 ms rf pulse width, and up to 5 pps repetition rate. The main features of this modulator are the use of four 50 kW switching power supplies in parallel to charge the storage capacitors to 10 kV, self-healing-type capacitor to realize a compact storage capacitor bank, and a highly reliable IGBT switch which enables elimination of a crowbar circuit. Design considerations and its performance are presented. An IEGT (Injection Enhanced Gate Transistor) switch, composed of six series devices with a rating of 4.5 kV and 2100 A-DC, has been also developed and tested for R&D to realize a compact modulator.