An overmoded relativistic backward wave oscillator with efficient dual-mode operation

TLDR

The TM02 mode, with a phase velocity roughly twice that of the TM01 surface harmonic, is significant for high‑power microwave generation. The study presents a dual‑mode operation mechanism for an overmoded relativistic backward wave oscillator. The mechanism involves synchronous interaction of the electron beam with the −1st space harmonic of the TM01 mode, followed by conversion of the backward TM01 mode into a forward TM02 mode. Particle‑in‑cell simulations demonstrate a 48 % efficiency and a marked increase in power capacity.

Abstract

A dual-mode operation mechanism in an overmoded relativistic backward wave oscillator is presented. The electron beam interacts with the −1st space harmonic of TM01 mode synchronously in the slow wave structure. Then the backward propagating TM01 mode is converted to the forward propagating TM02 mode. As the phase velocity of the volume harmonic of TM02 mode is about twice that of the surface harmonic of TM01 mode, the TM02 mode also plays an important role in the high-power microwave generation. Particle-in-cell simulation shows that an efficiency of 48% and a significant improvement of the power capacity have been obtained.