• Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, A. Takagi
  KEK, Ibaraki
• D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf
  ANL, Argonne
• T. Oki
  Tsukuba University, Ibaraki

A low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by collaboration between Argonne National Laboratory (US), KEK (Japan) and Rutherford Appleton Laboratory (UK). The system has less than 30 Ω of output impedance over wide frequency range of 2.7-6.2 MHz. However, distortions of voltage waveform in the driver stage have been a long-standing issue. It was found such distortions were generated depending upon the higher-order-modes of the anode-choke impedance. In this report, method to realize the smooth sinusoidal waveform in the wideband system is presented.

• S. Hatori, S. Fukumoto, Y. Hayashi, H. Kagawa, T. Kurita, E.J. Minehara, S. Nagasaki, Y. Nakata, T. Odagiri, M. Shimada, H. Yamada, F. Yamaguchi, H. Yamamoto, M. Yodose
  WERC, Tsuruga , Fukui

We have operated the accelerator system which consists of a tandem accelerator and a synchrotron since the completion of the construction and beam commissioning at the Wakasa-wan Energy Research Center, Tsuruga, Japan in 2000. The acceleration voltage of the tandem accelerator amounts to 5 MV and is generated by the Dynamitron-type cascade voltage doubler rectifier. The beam from the tandem accelerator is transported to the MeV-ion experimental area for the irradiation to the industrial or biological material and for the ion beam analysis. The tandem beam is also injected to the 200 MeV proton synchrotron. The synchrotron beam has been used for the high energy irradiation and the cancer therapy. The tandem accelerator is used for a lot of purposes including cancer therapy, therefore, stable operation of the system and efficient sharing of the operation duration are required. Developments of the accelerator are presented putting a stress on the stable and efficient operation of the system in this paper.