Investigation of a Low-Impedance Reltron as a Gigawatt HPM Source

In this paper, a novel version of reltron has been proposed for the gigawatt power level of microwave generation. It uses a modified modulation cavity structure, in which the electromagnetic field coupling has been made through two coupling cavities instead of one coupling cavity as in the conventional case. This low-impedance device allows higher beam current at lower applied dc pulse potential, producing larger RF power. Particle-in-cell simulation for a typical 500-kV dc voltage and 15-kA beam current, the modified reltron radiates an average power of ~2.2 GW with ~14.7% efficiency. Here, virtual cathodes do not form during device oscillation, which facilitates longer pulse and repetitive pulse operation.