Numerical simulation of a processes in the cavity of 170 GHz/CW/1 MW gyrotron for iter

We study two versions of a gyrotron operating in the TE_28.7 and TE_31.8 modes for electron-cyclotron heating of plasma in the international thermonuclear reactor ITER. The gyrotron cavity parameters are optimized allowing for ohmic losses, dips in electron beam potential, and velocity spread. The influence of the ion compensation for the space charge, the setting of oscillations at when the gyrotron is switched on, and the competition between the operating and parasitic modes are discussed. The possibility of attaining an efficiency of 32 to 36% for a specific power of ohmic losses in the cavity of less than 2.5 kW/cm² in the TE_28.7 mode and 2 kW/cm² in the TE_31.8 mode is demonstrated. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 6, pp. 788–797, June, 1997.