Author: Morishita, T.
Paper Title Page
THPWO034 Fabrication of the RFQ III for the J-PARC Linac Current Upgrade 3839
  • T. Morishita, Y. Kondo, H. Oguri
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Hasegawa
    JAEA, Ibaraki-ken, Japan
  • H. Kawamata, F. Naito, T. Sugimura
    KEK, Ibaraki, Japan
  The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400MeV) and current (to 50mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the RFQ III, which is designed for 50mA beam acceleration, has been fabricated. The engineering design and the fabrication technologies are basically the same as the RFQ II in J-PARC linac. Some engineering methods are improved for the dimension accuracy, the reliability, and the period of fabrication. In the RFQ II fabrication, there was a leakage trouble at the electron-beam-welding spot by the thermal stress at the brazing only occasionally. Then, we changed to all-brazing design. Also, there was a vane deformation after the final machining. This was corrected by changing the method of fixation at the brazing. As a result, a dimension error was in a tolerable range. Currently, the fabrication is in a final process and the high-power test is scheduled at the second quarter of 2012.