Transport transitions at high electron cyclotron resonance heating powers at the L-2M stellarator

Abstract

The experimental results are presented from the experiments on the high-power electron cyclotron resonance heating (ECRH) of the current-free plasma with the power 200–500 kW (the specific power was 0.8–2 MW/m3). The spontaneous transport transitions were observed that resulted in an increase in the plasma density and energy. At the ECRH powers exceeding 150 kW, the processes are observed accompanied by the abrupt changes in the plasma edge parameters, while the core plasma parameters change only slightly. At the ECRH powers exceeding 400 kW, a jump-like increase in the plasma density and energy is observed. At a power of approximately 500 kW, the regime was obtained, in which at time of transition, the plasma energy and lifetime increase by 20%, despite a decrease in the electron temperature. At the same time, at heating powers up to 700 kW, the energy lifetime corresponds on average to the L-2M single-machine stellarator scaling.