The machine protection system for CSNS

The China Spallation Neutron Source (CSNS) accelerator consists of an 80 MeV H- LINAC, a 1.6 GeV rapid cycling synchrotron (RCS) and two beam transport lines. The uncontrolled beam may permanently damage the components or lead to very high residual radiation dose along the beam line. So the equipment protection must be deliberately designed and implemented. The machine protection system (MPS) protects components from being damaged by the beam. The response time requirement for the CSNS MPS is less than 20 ms, so the PLC (programmable logic controller) was adopted to implement the interlock logic. The MPS was implemented as a two-tier architecture system, and developed through utilizing PLC and Experimental Physics and Industrial Control System (EPICS) software toolkits. The application logic was taken into careful consideration during the implementation stage. An embedded CPU module can function as an IOC accessing PLC I/O modules through the sequence CPU, with an embedded Linux operation system. The interlock logic and heartbeat functions were tested with all functions ok. Time consumption has been measured thoroughly since the important requirement, which is around 15 ms to stop the beam. MPS was completed in Sep. 2017 and then put into operation. It has been operating smoothly for more than 3 years. MPS has played an important role in every stage of CSNS’s commissioning and operation and achieved high reliability during the user’s experiment operation. The accelerator recently runs stably with low equipment failure.