Recovery of Plasma Electron Temperature Profile from Data of ECE Diagnostics and Relative Calibration of Its Frequency Channels in Ohmic Heating Regime at the L-2M Stellarator

Abstract

A technique is proposed for reconstructing the electron temperature profile under conditions when the integral absorption coefficient of electron cyclotron emission (ECE) is less than unity. Numerical simulations of plasma ECE were performed for the L-2M stellarator in the ohmic heating regime. It is shown that the radiation temperature profiles recovered from the ECE diagnostics data in the ohmic heating regime require considerable correction. The profile width turns out to be smaller than the width of the true temperature profile, and the on-axis plasma temperature is underestimated by ~30%. A new method is proposed for the relative calibration of ECE diagnostics channels in the ohmic heating regime. The resulting calibration coefficients can be used to measure the plasma temperature in the electron cyclotron resonance heating regime.