Numerical analysis of non-axisymmetric mode radiation from a high power backward wave oscillator with beam having perpendicular velocity component

Abstract

Summary form only given. The mechanism of radiation from backward wave oscillators (BWO's) has been considered to be a Cherenkov interaction of a streaming electron beam with a slow wave structure (SWS). Mostly, analyses have considered an electron beam without a perpendicular velocity component in a sufficiently large guiding axial magnetic field, and have assumed TM mode radiation. In actual experiments, however, the output from BWO's depends on the strength of the magnetic field, and non-axisymmetric modes have been observed in some experiments. Accordingly, we explore the possible presence of resonantly enhanced radiation connected with the cyclotron motion of the beam electrons with perpendicular velocity component in a finite strength magnetic field. From a linearized kinetic equation and a relativistic momentum distribution function, we derive nine dielectric tensor components in cylindrical coordinates for a beam with perpendicular velocity in a finite strength axial magnetic field. We assume an electromagnetic field with non-axisymmetric modes in a corrugated metal wall SWS.