一种220 GHz分布作用速调管的高频系统模拟

对一种基于双排矩形波导慢波结构(SDRWS) 结构的3腔EIK进行了详细计算机模拟计算, 通过对基于SDRWS结构的EIK用输入输出腔的S11的模拟计算及对分布作用速调管用中间腔的本征频率的模拟计算, 初步确定了EIK用输入输出腔及中间腔的结构参数, 进而对EIK进行了PIC互作用模拟计算, 结果表明: 该EIK的3dB工作频带为219.5~220.5GHz, 3dB带宽为1GHz, 最大功率为456 W, 最大增益为40.06dB。在此基础上, 通过调整中间腔的波导头宽度以进行参差调谐, 用PIC互作用模型模拟计算研究了中间腔谐振频率对EIK整体性能的影响。结果表明, EIK的3dB工作频带主要由输入输出腔的通频带决定, 而中间腔的谐振频率也具有重要影响。当中间腔的谐振频率分别处于输入输出腔的通频带的低频端或高频端时, 可以使EIK的3dB工作频带向低频端或高频端得到一定程度展宽; 当中间腔的谐振频率高于输入输出腔的通频带的高频端时, EIK的增益在其3dB工作频带内较为平坦, EIK的输出信号在其3dB工作频带内比较稳定, 频谱的纯净程度较好。参差调谐的最终结果表明, 当中间腔的波导头宽度为0.747mm时, EIK获得了接近最优的性能, 3dB工作频带为219.5~220.0GHz, 3dB带宽扩展到1.2GHz, 最大功率为630W, 相应的最大电子效率为11.3%, 最大增益为47dB。

RF system of a 220 GHz extended interaction klystron

An extended interaction klystron (EIK), which is composed of an input cavity and an output cavity both based on 8 periods of staggered double rectangular waveguide structure (SDRWS) and an intermediate cavity based on 6 periods of SDRWS, is calculated in detail on computer.After calculating reflection coefficient S11 of the input cavity and output cavity and the eigenmodes of the intermediate cavity, the structural parameters of the input cavity and output cavity and the intermediate cavity are determined, then PIC simulation is done to predict the EIK's performance, the results show that the EIK has an 1 GHz 3 dB bandwidth (219.5-220.5 GHz), a 456 W maximum power and a 40.06 dB maximum gain.Furthermore, stagger tuning by adjusting the structural parameter aof the intermediate cavity is performed to analyse howaaffects the EIK's performances, and the results show that the 3 dB band of the EIK mainly depends on the passband of the input cavity and output cavity, it also depends on the resonant frequency of the intermediate cavity in some cases.When the resonant frequency of the intermediate cavity is located at the lower or higher ends of the passband of the input cavity and output cavity, the 3 dB band of the EIK may be extended to certain extent.Particularly, when the resonant frequency of the intermediate cavity is located at or beyond the higher ends of the passband of the input cavity and output cavity, it is verified that the EIK has steady output signal featuring with pure spectrum and flat gains over the 3 dB band.The final results of the stagger tuning show that, when the structural parameter aof the intermediate cavity is 0.747 mm, the EIK reaches almost the optimum performances, with an 1.2 GHz3 dB bandwidth (219.5-220.7 GHz), a 630 W maximum power companied with a 11.3%efficiency, and a 47 dB maximum gain.