Analysis and optimization of the characteristics of superpower virtode generation

We report on the results of the 3D numerical simulation of perspective design of an oscillator based on an external-feedback virtual cathode (virtode), as well as optimization of characteristics of its generation. We have analyzed the effect of beam parameters on the virtode output characteristics. In particular, we have obtained the dependence of the efficiency on the feeding voltage and on the current being injected. We have studied the effect of beam velocity premodulation and electron velocity spread on virtode generation characteristics. It has been established that the introduction of premodulation sharply increases the generation efficiency up to 13% for optimal parameters. The possibility of stable generation in the virtode at relatively large spread in electron velocities has been demonstrated.