A quasi-optical system converting an output radiation of a gyrotron into a Gaussian beam

High frequency gyrotrons are characterized by their abilities to deliver high powers in submillimeter wavelength range and the frequency step-tunability. Practically all applications require Gaussian beams as a power source. The quasi-optical system consisting of a quasi-optical antenna, two focusing mirrors and a filter is appropriate as a transmission line for frequency tunable gyrotrons operating at TE/sub 0n/ mode. As an illustration of our approach, we present results which demonstrate the applicability of the developed system for conversion of the radiation generated by the Gyrotron FU IVA. The examples include conversions of three TE/sub 0n/ modes (TE/sub 02/, 223 GHz; TE/sub 03/, 323 GHz; TE/sub 04/, 423 GHz) into Gaussian-like beams.