Optimizing nonstationary 38-GHz pulse-train relativistic backward wave oscillator with low guiding magnetic field

Characteristics of a compact relativistic backward wave oscillator (BWO) operating in the 8-mm wavelength range have been optimized using the results of experimental investigation and numerical simulations. The coefficient of electron beam power conversion into microwave pulses close to unity is obtained for electrons transported in inhomogeneous magnetic field (2.2–1.7 T) below the cyclotron resonance level. In a regime of train generation at a repetition frequency of 10 Hz, the peak power of ∼250-ps electromagnetic pulses amounted to 450–600 MW. Numerical simulations show good prospects for obtaining peak powers above 100-MW level using a BWO with a beam-focusing system based on high-coercivity permanent magnets.