Designed of a quasi-optical mode converter for 0.42THz high order mode gyrotron

A quasi-optical mode converter (QOMC) for a 0.42THz TE_17,4 mode gyrotron has been designed by theoretical analysis, numerical calculation, 3D simulation in this paper. The QOMC consists of a Denisov launcher and a set of beam-forming mirrors. The operation of the Denisov launcher has been analyzed by the coupling mode theory. The mirrors are used to form the beam-forming mirrors system. The vector diffraction theory is used to calculate the fields on the mirrors. A full 3D electromagnetic analysis of the integrated QOMC has been done. Results show that a conversion efficient of more than 98.1% has been obtained. Results of 3D simulations are in good agreement with the design calculation.