  The China Spallation Neutron Source (CSNS) uses H- stripping and phase space
painting method to fill large ring acceptance with the linac beam of small
emittance. The dependence of the painting beam on the injection beam parameters
was studied for the Rapid Cycling Synchrotron (RCS) of CSNS. The injection
processes for different momentum spread, rms emittance of the injection beam,
injection beam matching were simulated, then the beam losses, 99% and rms
emittances were obtained and the optimized ranges of injection beam parameters
were given. The interaction between the H- beam and the stripping foil was
studied and the foil scattering was simulated. Then, the stripping efficiency
was calculated and the suitable thickness of the stripping foil was obtained.
The energy deposition on the foil and the beam losses due to the foil
scattering were also studied.
