新型虚阴极振荡器的研究

 采用小信号理论，在考虑到透射、反射束电子不同作用下，分析了虚阴极振荡器产生微波的机制，获得了计算微波主频的方法，讨论了增强束波作用效率的方法，并提出一种新型结构的虚阴极振荡器。该振荡器的阳极后放置了一个谐振腔，谐振腔长度很小，虚阴极不能在其中形成，谐振腔受到反射电子束激励并建立强场，场对入射电子进行调制，同时采用同轴结构引出微波。利用2.5D PIC 程序对新型的结构进行了数值模拟，验证了理论分析的正确性。在入射电子束电子能量为520keV和电子束流12.5kA的条件下，获得微波平均功率为1GW，频率为3.66GHz，平均束波转换效率为15.3%。

Vircator with resonant cavity and coaxial extractor

A simple model was developed to investigate the generation mechanism of virtual cathode oscillation microwave based on space-charge effect under small signal condition. With this model, the generated microwave frequency in a vircator an be calculated. On the basis of theoretical analysis, an improved virtual cathode oscillator was brought forward. In this configure, a resonant cavity is located behind anode, the cavity is very small so that virtual cathode couldn't be formed in it, the reflected beem current may excited a cavity mode, which modulates injected beam; and microwave is extracted in coaxial structure.2.5D PIC numerical simulation was conducted to study it. Microwave pulse power of 1GW at 3.66GHz for 520kV and 12.5kA injecting e-beam was obtained, power efficiency was about 15.3%.