BEAM HALO REDUCTION IN THE J-PARC 3-GeV RCS

The RCS beam power ramp-up has well proceeded since the start-up of user program in December 2008. So far the RCS has successfully achieved high intensity beam trials up to 420 kW at a low-level intensity loss of less than 1%, and the output beam power for the routine user program has been increased to 210 kW to date. Recently our effort has also been made to improve the quality of the extraction beam, namely to realize low-halo high-power beams. In this paper, recent effort for beam halo reduction in the RCS will be presented.