Recent progress of J-PARC RCS beam commissioning; Towards realizing 1-MW output beam power

Hotchi, Hideaki  

The J-PARC 3-GeV RCS have successfully achieved a 1-MW beam acceleration in January 2015. In this beam test, a major part of beam loss, such as space-charge induced beam loss, was well minimized by the injection painting technique. In addition, in the recent beam test in June, 2015, the transverse painting area was successfully expanded by correcting beta function beating during injection with the newly installed quadrupole corrector system. By this effort, a foil scattering part of beam loss during charge-exchange injection was further reduced. In this talk, recent progress of RCS beam commissioning will be reported especially focusing on our approaches to beam loss issues that we faced on the process of the beam power ramp-up.