IHEP Beijing, Beijing
The China Spallation Neutron Source (CSNS) accelerator operates at 25 Hz repetition rate with an initial design beam power of 100 kW and is upgradeable to 500 kW. The accelerator of CSNS consists of a low energy linac and a Rapid Cycling Synchrotron (RCS). In this kind of high power accelerators, especially in the low energy end, the beam is space charge dominated, and the space charge effects are the main source of beam loss. The space charge effects limit the maximum beam density, as well as beam power. Many simulation works were done for the study of space charge effects for CSNS accelerators, by using code ORBIT , SIMPSONS and PARMILA. Various conditions are considered in simulations, including the effects of different lattice structure, different tune, the combine effect of sextupole field and space charge, the combine effects of higher order field, error and space charge effects, different painting beam distribution for RCS, etc. The beam loss and emittance growth are compared for different conditions. A brief introduction to beam dynamics design is also given.
IHEP Beijing, Beijing
China Spallation Neutron Source (CSNS) accelerator consists of a 80 MeV linac and a 1.6 GeV Rapid Cycling Synchrotron (RCS), which is designed to produce beam power of 100 kW with a repetition rate of 25 Hz. For such a high intensity RCS, beam loss and control are of primary concern. A two-stage collimation system is designed to localize the beam losses in a restricted area, and keep the uncontrolled losses less than 1 W/m at the other part of RCS. The detailed design of the beam collimation system is presented, including the compare among different schemes. Key issues which affect the collimation efficiency are analyzed, and the collimation efficiency and beam loss distributions are studied by using the code ORBIT.