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

Hotchi, Hideaki  

J-PARC RCS started 1-MW beam tuning from October 2014, and successfully achieved 1-MW beam acceleration in January 2015, where major part of beam loss, such as space-charge induced beam loss, was well minimized by the combination of transverse and longitudinal painting. In addition, very recently, the transverse painting area was successfully expanded by correcting beta function beating during injection caused by the edge focus of the injection bump magnets, by which the foil scattering part of beam loss was further reduced. By these efforts, now the beam loss is at the permissible level for the 1-MW routine beam operation. The main topic of this talk is to discuss our approaches to beam loss issues that we faced on the process of the beam power ramp-up.