Upgrade of the J-PARC Linac

Abstract

We have upgraded both the beam energy (400 MeV) and the peak beam current (50 mA) of the J-PARC linac to realize the nominal performance of 1 MW at the 3 GeV Rapid Cycling Synchrotron (RCS) and 0.75 MW at the 30 GeV Main Ring synchrotron (MR). For the energy upgrade, we installed an Annular-ring Coupled Structure linac (ACS) and 972 MHz klystron system during the summer shutdown of 2013. The result of the beam test showed the beam loss at the RCS beam injection area decreased significantly by increasing the energy. For the beam current upgrade, we replaced the ion source, the RFQ and the RF chopper system during the summer shutdown of 2014. The beam commissioning was started in September 2014, and the 1 MW equivalent beam operation was successfully demonstrated at the RCS in January 2015.