提出一种高效率预调制型同轴虚阴极振荡器，进行了数值模拟研究。研究表明：径向束流预调制型同轴虚阴极振荡器利用在束-波互作用区加载金属圆环形成谐振腔，改变束-波互作用区的电场，对电子束进行调制。圆筒形金属形成的调制腔产生的电场既对电子束进行了调制，同时对微波频率进行了锁定，其谐振频率主要是由加载的金属圆筒的长度和两个圆筒之间的径向距离决定。经过优化设计，在600 kV，73 kA无外加引导磁场的条件下，预调制型同轴虚阴极振荡器获得了平均功率6 GW，频率为2.575 GHz的微波输出，效率达到13.94%。

A new beam premodulation structure of the coaxial virtual cathode oscillator is proposed and numerically studied. Radial beam premodulation type coaxial virtual cathode oscillator has a metal ring in beam-wave interaction region forming a resonant cavity which changes the electric field distribution of the beam-wave interaction region and modulates the electron beam. The electric field generated by the buncher both modulates the electron beam, and locks the microwave frequency. The resonant frequency is dominated by the length of the metal cylinder and the radial distance between the two cylinders. Through optimization, applying a 600 kV voltage at 73 kA current without external guiding magnetic field, the generated microwave has an average power of 6.00 GW at 2.575 GHz operating frequency, the conversion efficiency reaches 13.94%.