Author: Hasegawa, K.
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.  
THPWO031 Status of J-PARC Accelerators 3830
  • K. Hasegawa, M. Kinsho, H. Oguri
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Koseki
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  After nine-months of beam shutdown by the Great Earthquake in March 2011, the J-PARC facility resumed beam operation. In December 2011, operations were carried out at low duty such as single-shots or 1 to 2.5 Hz for beam tuning. At the beginning of January 2012, we started beam tuning at the full repetition rate of 25 Hz at the linac and the 3 GeV Rapid Cycling Synchrotron (RCS). After the tuning, user programs of the Materials and Life Science Experiment Facility (MLF), the Neutrino facility and the Hadron facility started. The beam power was increased from 100 to 300 kW to the MLF users, from 3.3 kW to 6 kW to the Hadron users, and from 140 to 200 kW to the Neutrino users. The beam availability went lower to 73 % in JFY 2011 due to the trouble of the linac klystron power supply in March, but it has got back to 90-94 % as of November in JFY2012. We have also much upgrade work during the shutdown period or in parallel to the operation. We’ve demonstrated new record power beyond 500kW from the RCS. The status and progress of the J-PARC accelerators are presented.