Experimental Investigation of a Super Klystron-Like Relativistic Backward Wave Oscillator Operating With Low Magnetic Field

An investigation of a super klystron-like relativistic backward wave oscillator is presented in this article. To obtain high power and high efficiency, an additional anode cavity is used to promote electron-beam modulation. Additionally, two waveguide cavities at the end of the electron collector are employed to enhance the constructive resonance, which intensifies energy conversion from the modulated electron beam to the electromagnetic field. Because of the enhancement of centralized transition radiation, the power generated in the extractor constitutes over 95% of the total power. Consistent with the results from numerical simulations, microwaves with a power of 5.0 GW, a frequency of 4.4 GHz, and a pulsewidth of 36 ns were obtained in high-power microwave generation experiments with an external magnetic field of 0.42 T, in which the diode voltage and beam current were configured to be 815 kV and 15.5 kA, respectively, indicating a beam-wave conversion efficiency of 40%. The diode insulation was investigated experimentally, and an unfortunate shunting current of over 3 kA was observed when the working voltage was beyond 800 kV, which indicates an actual conversion efficiency of 33% in the diode region.