Design of a TE42,7 coaxial cavity for a 1 MW, 280 GHz gyrotron

To provide the required mode selectivity for a 1 MW, 280 GHz gyrotron, a coaxial resonator operating in the high order TE_42,7 mode is considered. Mode discrimination is achieved both by exploring selective ohmic effects and examining the electrodynamic properties of the coaxial cylindrical waveguide. Analytic results indicate the effectiveness of a coaxial insert with a low electrical conductivity in rarefying the mode density of overmoded, megawatt hollow cavities.