Quasi-coherent mode evolution in discharges with positive radial electric field at the T-10 tokamak

Abstract

The effect of the high-power ECRH on the quasi-coherent (QC) mode in the plasma of the T-10 tokamak with the magnetic field Bt = 2.2 T, plasma current Ipl = 230 kA and chord-averaged electron density <ne> ≈ 1⋅1019 m-3 is discussed. The most pronounced changes appear in the core plasma region with r < 0.5a. For the ECRH power PECRH = 2.2 MW causing the appearance of the positive radial electric field (in the OH stage, the occurring field is ), the mean frequency of the QC-mode gradually decreases from (in the OH stage) to , and its frequency spread Δf QC decreases from to . For the ECRH power PECRH = 1.7 MW and weak negative radial electric field (), the mean frequency decreases to , and the frequency spread becomes . After the ECRH-induced drop, the QC-mode mean frequency increases with increasing line-averaged density.