Effect of beam parameters on the space charge wave modes in slow wave structures with semi-circular and trapezoidal corrugation

Department of Electrical and Electronic Engineering, Islamic University of Technology (IUT), Board Bazar, 1704 Gazipur, Bangladesh

^a e-mail: gsaber@iut-dhaka.edu

Received: 14 April 2015
Revised: 11 July 2015
Accepted: 30 July 2015
Published online: 25 August 2015

Abstract

Corrugated waveguide with sinusoidal shape has long been used as slow wave structure (SWS) in backward wave oscillators (BWOs). Alternative SWSs with arbitrary geometries such as trapezoidal and semi-circular have drawn the attention of the researchers recently to be used as interaction regions in BWOs. In this work, the zero and non-zero beam dispersion characteristics of the axisymmetric transverse magnetic (TM) modes of semi-circularly and trapezoidally corrugated SWS (SCCSWS and TCSWS) have been studied numerically. The effect of variation of the electron beam parameters such as beam energy, current and radius on space charge wave modes (SCWM) and temporal growth rate (TGR) has also been investigated rigorously. The simulation results provide detail information regarding the unstable region where the resonant interaction occurs which is the requirement for microwave generation.