Multimode analysis and PIC simulation of a metal PBG cavity gyrotron oscillator

Abstract

This paper is devoted to the study of beam-wave interaction behavior of a 35GHz photonic band gap (PBG) cavity gyrotron operating in a higher order TE3,4,1 mode. For the present gyrotron, PBG cavity is used instead of conventional tapered cylindrical cavity due to its promising feature of the mode selectivity. In order to observe beam-wave interaction behavior, multimode theory has been used for the PBG cavity operating at the fundamental harmonic mode. Results obtained from the analysis have been validated using a commercially available 3D PIC code. The energy and phase variations of electrons demonstrate the bunching mechanism as well as energy transfer phenomena. RF power output obtained from the analysis as well as PIC simulation is compared and is found in close agreement within 12%. More than 45 kW of stable RF power output is achieved in TE3,4,1 mode with ∼ 17% efficiency. The existence of competing modes has been considerably reduced, and the single mode operation of PBG cavity gyrotron has been achieved. © 2014, Electromagnetics Academy. All rights reserved.