An Increase in Plasma Energy Lifetime in the Profiled-Pulse Regime in the L-2M Stellarator

Results of experiments carried out with a quasi-stationary L-2M stellarator in the regime of electron cyclotron resonance heating by means of two gyrotrons are presented. The data on increase in the plasma energy lifetime by means of modulation (profiling) of the microwave pulse are obtained. The first gyrotron operating at fixed power was used for ionization and initial heating of plasma, while the second gyrotron initiated a stationary discharge with a duration of 10 ms. It is demonstrated that the lifetime can be increased by varying the second-gyrotron power in the range of 50–200 kW. A fourfold increase in the lifetime was obtained when the second-gyrotron power was reduced to 50 kW. This work is of interest as a method of studying hot plasma confined in the toroidal magnetic system of a stellarator.