On the design of high conversion efficiency quasi-optical mode converter for 140 GHz high-power gyrotron applications

A high conversion efficiency quasi-optical mode converter prototype is designed for 140 GHz TE (22,6) ap. plications. The Denisov launcher is designed based on the periodic perturbation concept,leading to primary radia. tion field with low edge diffraction. Full-vector physical optics integration solver is used to model and analysis the 3-mirror system. And the 3-mirror iterative phase correction is applied based on the co-polarization field compo. nent,so as to achieve high-quality mode conversion. Specifically,the correction of the 1(st) mirror sufficiently re. fines the non-ideal radiated fields from the launcher. It is then validated by numerical investigations that,compar. ing to the original quaritic mirrors,the phase-shaped mirror system leads to excellent conversion performance: The Gaussian content(eta(v))of the output fields rises from 92. 7% to 99. 6%,while the power transmission efficien. cy(eta(p))reaches 98. 8%.