LLRF超导腔体控制系统的测试

中国科学院近代物理研究所自主研发的ADS注入器Ⅱ第一代高频低电平(LLRF)控制系统,工作频率为162.5 MHz;LLRF系统是由基于I/Q采样的正交解调技术构成的全数字闭环反馈控制系统,其主要功能是实现超导腔腔体电压幅值稳定控制、相位稳定控制与腔体谐振频率控制;LLRF控制系统在液氦温区超导腔上进行了系统稳定度和性能的在线测试,根据实验数据计算得超导腔体电压幅度稳定度为±3.4‰,相位稳定度为±0.3°,腔体表面峰值电场(Epk)能长时间稳定在25.1 MV/m。通过实验测试,检验了LLRF控制系统的性能,并对测试过程中出现的问题进行了分析,为将来超导腔LLRF控制系统运行积累了经验。

Test of LLRF Control System on Superconducting Cavity

The first generation Low-Level radio frequency(LLRF) control systemfor China ADS injector Ⅱis developed by IMP, CAS(Institute of Modern Physics, Chinese Academy of Sciences). This system is composed by superconducting cavity amplitude stability controller, phase stability controller and the cavity resonance frequency controller; the operation frequency is 162.5 MHz. This is an all-digital closed-loop feedback controlsystem which based on the IQ quadrature sampling demodulation technique. The performance of the system has been tested on the superconducting cavity, which is running in the temperature range of liquid helium and the Epk=25.1 MV/m (the peak electricon the surface of the superconducting cavity). The amplitude stability is lessthan .4 ‰ and the phase stability is less than 0.3°. Superconducting cavity bandwidth is about 230 Hz. From the spectrum, the phase noise suppression can reach 70 dBm.