Investigation of an improved relativistic backward wave oscillator in efficiency and power capacity

TLDR

The paper investigates a relativistic backward wave oscillator engineered for high efficiency and power, employing a TM021 mode resonant reflector to increase power capacity by about 1.7×. The RBWO design incorporates a TM021 resonant reflector to reduce pulse shortening and an extraction cavity at the slow‑wave structure’s end to intensify beam‑wave interaction, raising efficiency from <30% to >40%. Experiments produced 3.2 GW microwaves at 9.75 GHz with 27 ns pulses using a 910 kV, 8.6 kA electron beam, and the RBWO achieved efficiencies above 40% across 870–1000 kV.

Abstract

Investigation of relativistic backward wave oscillator with high efficiency and power capacity is presented in this paper. To obtain high power and high efficiency, a TM021 mode resonant reflector is used to reduce the pulse shortening and increase power capacity to about 1.7 times. Meanwhile, an extraction cavity at the end of slow wave structure is employed to improve the efficiency from less than 30% to over 40%, through the beam-wave interaction intensification and better energy conversion from modulated electron beam to the electromagnetic field. Consistent with the numerical results, microwave with a power of 3.2 GW, a frequency of 9.75 GHz, and a pulse width of 27 ns was obtained in the high power microwave generation experiment, where the electron beam energy was configured to be ∼910 kV and its current to be ∼8.6 kA. The efficiency of the RBWO exceeds 40% at a voltage range of 870 kV–1000 kV.