• J. Kamiya, Y. Hikichi, K. Kanazawa, M. Kinsho, N. Ogiwara, Y. Takiyama
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

Since the start of the beam commissioning on October 2007, we have succeeded to increase the beam power of the Rapid Cycling Synchrotron (RCS) in the Japan Proton Accelerator Research Complex (J-PARC). The effect of the high power beam on the vacuum had become visible above the beam power of 50 kW. When the high power beam was operated at 25 Hz, the vacuum pressure became higher. Especially the vacuum of the injection area became worse than other areas. The residual gas analyzer was installed in order to investigate which kinds of outgassing were desorbed by the high power beam. The carbon compound mainly increased with the high power beam in the area. The source of the ougtassing is thought to be carbon foils for charge exchange and/or a electron catcher which was installed in order to collect the stripped electron by the carbon foil. After this, the RCS forwards into the stage where the high power beam is continuously operated during a few weeks. We will report the results of the conditioning effect on the vacuum by the beam itself.

• H. Hotchi, N. Hayashi, Y. Hikichi, S. Hiroki, J. Kamiya, K. Kanazawa, M. Kawase, M. Kinsho, M. Nomura, N. Ogiwara, R. Saeki, P.K. Saha, A. Schnase, T. Shimada, Y. Shobuda, K. Suganuma, H. Suzuki, H. Takahashi, T. Takayanagi, O. Takeda, F. Tamura, N. Tani, T. Togashi, T. Ueno, M. Watanabe, Y. Watanabe, K. Yamamoto, M. Yamamoto, Y. Yamazaki, H. Yoshikawa, M. Yoshimoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• A. Ando
  LASTI, Hyogo
• H. Harada
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• K. Hasegawa, Y. Irie, C. Ohmori, M. Yoshii
  KEK, Ibaraki
• K. Satou, Y. Yamazaki
  J-PARC, KEK & JAEA, Ibaraki-ken

The beam commissioning of the J-PARC 3-GeV RCS started in October 2007. The initial machine parameter tuning and underlying beam studies were completed in February 2008 through various beam dynamics measurements, such as optical functions, turn-by-turn beam positions, and transverse and logitudinal beam profiles. Now the RCS is in transition from the first commissioning phase to the next challenging stage and our efforts hereafter will be focused on higher beam power operations. In this paper, we describe experimental results obtained in the high intensity demonstrations in October 2008, together with the corresponding simulation results.