Stability of gyrotron operation in very high-order modes

This study was motivated by the desire to increase the power, which can be delivered by gyrotrons in long pulse and continuous regimes. Since the admissible power level is determined by the density of ohmic losses in resonator walls, to increase the radiated power a gyrotron should operate in higher order modes. Using an existing gyrotron developed for plasma experiments in the International Thermonuclear Experimental Reactor as a base model, the stability of operation of such a gyrotron in modes with larger number of radial variations was studied. It is shown that the power level achievable in such gyrotrons in stable single mode regimes is close to 1.5 MW. The power level 1.7–1.8 MW can b…