The design of a quasi-optical mode converter for a coaxial-cavity gyrotron

A quasi-optical mode converter is used in the TE/sub 34,19/, 2 MW, CW 170 GHz coaxial cavity gyrotron, which is under development at FZK. The cut of the launcher has been optimized taking the tapering angle of the launcher into account. Further on, the amplitude of the launcher corrugations have been optimized for improved focusing in order to reduce the diffraction losses at the cut. In addition, the influence of phase corrections of a non-quadratic mirror on wave properties has been investigated for a real fabricated surface in comparison to the measurement. Results are reported.