Highly Efficient Quasi-Optical Mode Converter for a Multifrequency High-Power Gyrotron |
| |
Authors: | Prinz O. Arnold A. Gantenbein G. Ying-hui Liu Thumm M. Wagner D. |
| |
Affiliation: | Inst. fur Hochstfrequenztechnik und Elektron., Univ. Karlsruhe, Karlsruhe; |
| |
Abstract: | A highly efficient quasi-optical mode converter with a bandwidth of 38 GHz has been designed and tested. The mode converter combines low-diffraction losses and a Gaussian mode content up to 97% for a set of nine modes in the range of 105 to 143 GHz for a 1-MW CW gyrotron. This was achieved using a dimpled-wall waveguide antenna (launcher), one quasi-elliptical mirror, and two toroidal mirrors. The optimization of the launcher was done using coupled-mode theory. The simulation results show a well-focused Gaussian beam for all nine operating modes. The curvature radii of the toroidal mirrors were determined by Gaussian mode transformation (ABCD-law) and subsequently optimized for a multimode operation. The simulations of the quasi-optical mode converter are based on the electric field integral equation and, thus, are 3-D. Experimental low-power measurements show close agreement with predictions. |
| |
Keywords: | |
|
|