Development of 170 GHz gyrotron for ITER

The new design of 170 GHz/1 MW/50% gyrotron with depressed collector and diamond window is reported. First stage testing of this gyrotron with BN window was completed. Output power of 950 kW and efficiency up to 44% were achieved. Pulse duration of 0.4 s was limited by BN window capacity. BN window was replaced then with the diamond one and second stage testing started with low power regime. Pulse duration of 20 s was reached at 250-kW power level.