Energy Confinement Dynamics and Soft X-Ray Spectra in Experiments on ECR Plasma Heating in the L-2M Stellarator at Heating Powers to 1 MW

The shape of soft X-ray spectra and energy confinement dynamics is studied in experiments on central ECR heating with a power to 1 MW using the L-2M stellarator. It is shown that the spectra remain two-temperature with increasing heating power. In this case, the average electron energy in the epithermal spectral region increases reaching 25% of the average energy over the entire spectrum at an ECR heating power of 950 kW. It is shown that the plasma confinement energy in the L-2M stellarator gradually decreases at heating powers above 700 kW, which is associated with an increase in the plasma radiative loss power, caused by impurity accumulation.