Design and performance of the LLRF system for CSNS/RCS

The rapid cycling synchrotron(RCS) is part of the China Spallation Neutron Source(CSNS). The RCS provides 1.6 Ge V protons with a repetition rate of 25 Hz. The RF system in RCS is mainly composed of a ferrite loaded RF cavity, a high power tetrode amplifier, a bias supply of 3300 A 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 the heavy beam loading effect. A total of eight control loops are applied to ensure the normal operation. An effective feedforward scheme is widely used to improve the dynamic performance of the system. The design of the LLRF system and high power integration test results with the prototype RF system are presented.     

CSNS/RCS环射频腔用铁氧体环测试系统研制

为测试环射频铁氧体加载同轴谐振腔中铁氧体环的性能和批量筛选铁氧体环,研制了铁氧体双环测量系统。与国内外同类设备相比,该系统采用了扫频测量的闭环控制,可以模拟射频腔的运行工况、实现对铁氧体环性能的动态测量。扫频范围测量结果表明:该测试系统满足在0~3 000 A偏流调谐范围内的1.02~2.44 MHz频率覆盖要求,固定频率点的高功率测量结果和材料性能参数与日本J-PARC测量数据吻合。