固态功率源功放模块反射功率过荷分析

Analysis of the over-loaded reflection of solid state power amplifier module

中国加速器驱动次临界系统(Chinese Accelerator Driven Sub-critical System,C-ADS)注入器II超导直线加速器采用固态功率源驱动常温加速结构和超导腔,运行中出现了功率源的功放模块因反射功率过荷而损坏的现象。为此研究了反射功率在模块间的分配与功率合成网络S参数以及模块输出状态的关系。结果表明:如果个别功放模块无功率输出,合成失衡会导致反射功率在模块间的不平衡分布,部分模块承受的反射功率将超过其实际承受能力。对于一级合成的功率源,只有失效模块承受的反射功率可能超限;对于多级合成的功率源,失效模块以及同一合成支路的正常模块均存在反射功率过荷的可能性。

[Background] C-ADS (Chinese Accelerator Driven Sub-critical System) injector II superconducting linac uses solid state amplifier (SSA) to drive normal temperature acceleration structure and superconducting cavity. During operation, some power amplifier modules of SSA were damaged due to overload of reflected power.[Purpose] This study aims to analyze the reasons that caused over loading of SSA.[Methods] The relationship between the distribution of reflected power among the amplifier modules, the S parameters of power combination network, and various output states of amplifier module is derived and analyzed.[Results] The results showed that the failure of amplifier module would cause the unbalanced of reflected power distribution among modules. Some modules would undertake the reflection above normal level.[Conclusions] For the SSA with one-stage combined net, only failure module probably undertakes over loading reflected power;for the SSA of the multi-stage combined net, any module in the combined branch where the faulty module was located may have an overload reflection.