ANNULAR-RING COUPLED STRUCTURE LINAC FOR THE J-PARC LINAC ENERGY UPGRADE

摘要

The Japan Proton Accelerator Research Complex (JPARC) linac is the injector to the 3-GeV rapid cycle synchrotron. To increase the beam power of the synchrotron, the task of upgrading the energy of the linac to 400 MeV started in March 2009. At the downstream of the 191-MeV separated-type drift tube linac, 25 modules of the annularring coupled structure (ACS) linac will be added in August 2013. Cavity fabrication of the ACS is nearly complete, and the completed modules are kept at the J-PARC site. Currently, pumps and vacuum components are being installed on the cavities for testing of vacuum conditions. For the J-PARC pulsed beam, vacuum pressures need to be less than 10~(-5) Pa along the beam line in order not to exceed 0.1 W/m beam loss. In this paper, we present the measurement results for reducing the vacuum pressure using the stored ACS cavity to enable the high-intensity operation.