Author: Ogiwara, N.
Paper Title Page
MOPPD053 Reduction of Outgassing from the Ferrite Cores in the Kicker Magnet of J-PARC RCS 487
  • N. Ogiwara, Y. Hikichi, J. Kamiya, M. Kinsho, M. Nishikawa, K. Suganuma, T. Yanagibashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  Kicker magnets are used to kick out the accelerated beam to the beam transport lines in the RCS of the J-PARC. A high voltage is applied to kickers for a short period, so they must be installed in a vacuum to prevent discharge. Therefore, it is important to reduce the outgassing of water vapor from the ferrite cores. After bake-out at 200°C for 300 hours, the outgassing rate decreased to less than 1×10-7 Pam/s. However, the small amount of water vapor and carbon monoxide were emitted from the ferrite cores at charging voltage of 80 kV. This time, we have decided to construct the reserve magnets with very low outgassing at high-voltage discharge. First of all, the thermal desorption behavior of the ferrite was investigated. Water vapor has two peaks: at ~ 100°C and 350°C. Carbon monoxide is rather largely emitted until 300°C. From these results, the ferrite cores were vacuum-fired at 450°C for 10 h. Then the good properties for the magnetic cores were confirmed. And now the assembling of the kicker magnet is undertaken. The performance of the kicker magnet made of the vacuum-fired ferrite will be shown in this meeting.  
WEPPD013 Status of the Vacuum System in J-PARC RCS 2522
  • J. Kamiya, Y. Hikichi, M. Kinsho, M. Nishikawa, N. Ogiwara, T. Yanagibashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  In the vacuum system of J-PARC Rapid cycling synchrotron (RCS), we use beam pipes and bellows whose materials are vacuum fired at 700~850 oC in order to eliminate atoms in their bulk who are origin of outgassing. Until now, beam power has been increased up to 300 kW. Pressure in synchrotron beam line increased when the high power beam was accelerated. However, increment of pressure has reduced during the continuous beam operation. It is because the molecules, which adsorb on surface of the wall of the vacuum chambers, desorb by an ion bombardment and a heat generation due to an eddy current. Because the atoms in the bulk is eliminated, desorption of the molecules, which adsorb on the surface, means the reduction of the outgassing from the wall. In this presentation, we will report the past situation of the vacuum system during the beam operation. In addition, we also show the status after the Great East Japan Earthquake.