Optimal synthesis of quasi-optical launchers for high-power gyrotrons

Quasi-optical launcher designs for high-power gyrotrons use perturbations of the waveguide surface following the cavity to convert the high order cavity mode to a Gaussian-like beam, which is then radiated from a spiral cut of the waveguide. The design technique of these launchers is based on an analytic theory that specifies the mode amplitudes to obtain a Gaussian-like distribution of the field in the azimuthal and longitudinal directions. This approach can generate a beam with high Gaussian content and low diffraction losses. However, by adjusting the mode amplitudes to obtain a Gaussian-like distribution of the field in the radial (instead of the azimuthal) direction, designs with significantly less diffraction loss, reduced beam divergence angles, and higher Gaussian beam content can be achieved.