Design of a Quasi-Optical Launcher for 263 GHz Low Order Mode gyrotron

In this paper, a Quasi-Optical launcher operating at 263 GHz with low order TE3,2 mode is designed for THz gyrotron at Wuhan National High Magnetic Center (WHMFC). A TE3,2 to TE
8,3
mode converter is designed up front, because the lower-order operating mode TE3,2 does not follow the mode selection rules for Denisov-type launchers. The launcher consists of a left-handed (LH) TE3,2 to right-handed (RH) TE
8,2
11-fold helically corrugated waveguide mode converter, a TE
8,2
to TE
8,3
azimuthally symmetric ripple-wall waveguide mode converter and a Denisov-type launcher. A coupled-wave theory MATLAB code for analysis of the electromagnetic fields at the deformed waveguide wall has been developed. The commercial simulation result shows the launcher can generate a Gaussian-like mode with a scalar correlation coefficient of 93.50% and a vector correlation coefficient of 85.65% at the launcher aperture.