Numerical design and analysis of parasitic mode oscillations for 95 GHz gyrotron beam tunnel

The beam tunnel, equipped with the high lossy ceramics, is designed for 95 GHz gyrotron. The geometry of the beam tunnel is optimized considering the maximum RF absorption (ideally 100%) and the suppression of parasitic oscillations. The excitation of parasitic modes is a concerning problem for high frequency, high power gyrotrons. Considering the problem of parasitic mode excitation in beam tunnel, a detail analysis is performed for the suppression of these kinds of modes. Trajectory code EGUN and CST Microwave Studio are used for the simulations of electron beam trajectory and electromagnetic analysis, respectively.

► Design of beam tunnel using AlN–SIC lossy ceramic material for 95 GHz gyrotron. ► Scattering matrix analysis of RF behavior of beam tunnel. ► Analysis of parasitic mode oscillations in beam tunnel. ► Analysis of the possibility of beam–wave interaction in beam tunnel by using dispersion diagram.