Radiation output system for planar gyrotron

Gyrotrons with planar resonator cavity offer some advantages over conventional cylindrical ones for submillimetre wavelengths. The radiation in the planar gyrotron should be converted from the mixture of several high modes of the rectangular waveguide into the Gaussian beam with high efficiency. For the experimental 145 GHz gyrotron, a two channel output is considered. Both channels consist of waveguide converter and two convex mirrors and direct the radiation through the single output window. Calculated total efficiency of the system exceeds 98%.