A new radial three-cavity structure of the coaxial virtual cathode oscillator is proposed and studied numerically in this paper.Using the radial three-cavity structure,the beam-wave conversion efficiency is enhanced by modulating the electric field in the beam-wave interaction area,while the resonator composed of the radial three-cavity configuration and the mesh anode helps restrain mode competition effectively.And then the coaxial extraction structure benefits the energy extraction,and it can also absorb the used electrons entering into the drifting tube.Therefore,this new kind of virtual cathode oscillator can achieve a high output power.With an electron beam of 50 kA at 400 kV,a peak power of about 6 GW is achieved by simulation at 4.5 GHz.The mean power reaches 3.1 GW and the beam-wave conversion efficiency is about 15%.%提出了一种新型径向三腔同轴虚阴极振荡器,并进行了数值模拟研究.研究表明：这种径向三腔结构在束波转换面进行电场调制,能够大幅提高束波转换效率;同时,由阳极栅网和径向三腔结构构成的谐振装置能有效地抑制模式竞争;另外,由于采用了同轴引出结构,在提高能量引出的同时还能有效吸收漂移管中被利用过的电子,因此这种新型虚阴极振荡器能够获得较高的输出功率.模拟的电子束电压为400kV,电流为50kA,主频为4.5GHz,峰值功率达到6GW,平均输出功率为3.1GW,束波转换效率达到15%.
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