Design of the collector in a coaxial relativistic backward wave oscillator

In this paper, a compact L-band coaxial relativistic backward wave oscillator (RBWO) is designed using the 2.5 D particle simulation code. The advantage of a coaxial extractor instead of the conventional collector in enhancing efficiency is analyzed theoretically. Detailed physical interactions of the device with and without the coaxial extractor are investigated through KARAT code, respectively. The efficiencies in such two cases are compared. Simulation results show that under the same parameters (700keVand 11.5kA), the beam-to-microwave efficiency is increased from 14% for no extractor to about 30% using the coaxial extractor. The results show that the coaxial BWO with the coaxial extractor has great promise for high-efficiency microwave generation.