PIC simulation study of Beam Tunnel for W- Band high power Gyrotron

This paper presents the analysis of parasitic mode generation and its absorption inside a high-power gyrotron beam tunnel. Beam tunnel consists of four sections, out of which one section (near cavity) has been considered for the analysis. Dispersion curves are drawn to find out the possibilities of parasitic mode interaction with the electron beam. Beam tunnel structure has also been studied in Particle in Cell (PIC) solver of CST and power-sharing and frequency of various modes of oscillations have been recorded. To reduce the parasitic mode interaction, alternate rings of Copper and lossy ceramics are used in beam tunnel development.