Chromatic correction for CSNS/RCS and nonlinear effects of chromaticity sextupoles

In order to meet special requirements of the high intensity accelerator for collimators with good heat dissipation performance, radiation protection performance, ultra-high vacuum, high positioning accuracy, high stability, and online real-time adjustments, researches have been done for the primary collimator of rapid cycling synchrotron of China Spallation Neutron Source (CSNS/RCS). To ensure the reliability of design for the CSNS/RCS primary collimator, the technical difficulties of the key components, such as the scraper, vacuum chamber, driving system and remote clamp are also discussed. Thermal analysis of the scraper and structure analysis of support parts have been completed by using ANSYS code. Radiation shielding is simulated with FLUKA program.