Experimental Study of a Stabilized 230-GHz Gyrotron-Driver for Frequency Locking of Megawatt-Level Gyrotrons

This brief presents the results of experimental study of a 230-GHz gyrotron-driver designed for the frequency locking of a prototype megawatt-power gyrotron for plasma heating and current drive in the next generation of fusion power plants, such as tokamaks TRT and DEMO. The driver provides the output power of up to 130 kW at TE18,8 operating mode in a free-running regime. The frequency tuning dependencies on the magnetic field, cavity temperature, accelerating, and anode voltage are measured. When the generation frequency is stabilized using a phase-locked loop system controlling a modulating anode voltage, the radiation power is reduced to 60 kW. The obtained power and frequency tuning are sufficient for a fairly wide (~40–50 MHz) locking band of the implemented megawatt gyrotron.