Characteristic features of SXR spectra measured in the stage of initial ECR plasma heating in the L-2M stellarator

Abstract

SXR spectra measured in the stage of initial plasma heating in the L-2M stellarator were analyzed. It was ascertained that the two-slope SXR spectra usually measured in the quasistationary stage of the L-2M shots are not observed in the stage of initial plasma heating. In the initial stage of plasma heating, the suprathermal electrons are not generated. The electron temperature profiles were also measured in this stage. In contrast to the temperature profiles measured in the quasi-stationary stage of the discharges which have flat top in the radial range of r/ap ≤ 0.4, the temperature profiles measured in the stage of initial plasma heating have narrow shape. The differences in some plasma properties in two stages of plasma heating which result in different shapes of SXR spectra and temperature profiles are discussed.