Space charge effects for JPARC main ring

Abstract

J-PARC Main Ring (MR) should provide the beam power up to 0.8 MW at the maximum energy of 50 GeV. The total beam intensity in this case should be 3.3e14. According to the basic machine parameters the harmonic number of MR is 9, the number of bunches around the ring is 8. The power of the bunch is about 6 kW at the injection energy of 3 GeV. At the beginning of the high power operation we expected to get about 2 kW per bunch. Limitation the uncontrolled particle losses for the high-intensity beam accelerators is one of the most serious issue. The MR collimator should cut the tail particles during the injection process and at the beginning of the acceleration. Acceptable power of the lost beam at the scraper is about 500 W, which is about 1% from the beam power at the injection energy. In frame of this report we analyze the combined effect of the low-energy space charge and the lattice' resonances, caused by the machine imperfection for different machine operation scenario including the collimation system of the 3-50 BT beam line between RCS and MR and the MR collimator system. The measured field data for main magnets of MR has been used for this study. The budget of the particle losses during the injection and acceleration processes for the MR operation have been established.