Design and Experiment of a long-pulse high-power 170GHz gyrotron

The MW gyrotrons are key devices in ECRH of magnetic confinement nuclear fusion systems. In order to achieve the high-power and long-pulse of the 170GHz gyrotron, which are adopted in the CFETR, a $\mathbf{TE_{25.10}}$ -mode 170GHz gyrotron research are given in this paper. A single-anode magnetron injection gun (MIG) and the cylindrical resonant cavity operating are designed and optimized by PIC. The theoretical output power of the gyrotron with operating Voltage 75 kV, electron current 45 A is about 1.1 MW, corresponding to electron efficiency of 32.6%. The prototype of the gyrotron has been fabricated and tested preliminarily. The First results of the 170 GHz gyrotron experiments are that an output power of $\boldsymbol{\sim 350}\ \mathbf{kW}$ with Gaussian beam is achieved at 15-ms pulse length in operating voltage 52.2 kV, electron beam 40 A.