Development of 154/116 GHz Dual-Frequency Gyrotron for the Large Helical Device

Abstract

Based on the successful results of three 77 and two 154 GHz gyrotrons development and their contributions to large helical device (LHD) plasma experiments, a new 154/116 GHz dual-frequency gyrotron was developed. The optimal combination of cavity oscillation modes for dual-frequency oscillations at 154 and 116 GHz and optimal designs for the electron gun, cavity, mode converter, RF transmission mirrors, output window, and collector were determined. In an experimental test of the 154/116 GHz dual-frequency gyrotron, maximum powers of 1.66 and 1.34 MW were achieved at 154.05 and 116.15 GHz with pulse widths of 2.5 ms, respectively.