Design and performance of LLRF system for CSNS/RCS
  The rapid cycling synchrotron (RCS) is part of China Spallation Neutron Source (CSNS). The RCS provides 1.6GeV protons with a repetition rate of 25Hz. The RF system in RCS is mainly composed of a ferrite loaded RF cavity, a high power tetrode amplifier, a bias supply of 3300A and a digital low level RF (LLRF) system based on FPGA. The major challenge of the LLRF system is to solve problems caused by rapid frequency sweeping and heavy beam loading effect. This paper will present the design and structure of the LLRF system, and show results of performance tests. 
Li Xiao, Sun Hong, Long Wei, Zhao Fa-Cheng, Zhang Chun-Lin
physics.acc-ph