Path to 1-MW at J-PARC Rapid Cycling Synchrotron

The accelerator system at Japan Proton Accelerator Research Complex (J-PARC) has been operational since May 2008 and has mainly been used to perform physics experiments. The accelerator system consists of a Linac, a Rapid Cycling Synchrotron (RCS), and a Main Ring Synchrotron. The originally designed RCS injection energy is 400MeV, but the first operation started at 181MeV. New acceleration cavities were installed in J-PARC Linac during the summer shutdown of 2013, and user operation by the Material and Life science Facility (MLF) at the injection energy of 400MeV was started from February 2014. Post beam commissioning of 400MeV injection energy, beam loss was small enough, and we established 300kW continuous operation. Subsequently, the peak current of the Linac was increased from 30mA to 50mA. This upgrade enabled us to try 1-MW beam acceleration. Finally, after some additional improvements, we successfully accelerated 1-MW equivalent protons.