THE M=2, N=1 MODE SUPPRESSION BY ECRH ON THE T-10 TOKAMAK

Experiments on m = 2, n = 1 tearing mode suppression and on avoidance of density limit disruptions by electron cyclotron resonance heating ( ECRH) were performed on the T-10 tokamak. Partial suppression of the m = 2, n = 1 mode by the high frequency (HF) power deposition in the vi cinity of the q = 2 surface was observed. Development of external kink modes with HF power injection can result in m = 2, n = 1 mode destabi lization under specific operating conditions. ECRH suppresses m = 2, n = 1 mode activity at extremely high values of electron densities and prevents the density limit disruptions practically independently of EC resonance position. Complete compensation of the additional periphera l heat losses near the density limit by ECRH should be responsible for this result. No effect of electron cyclotron current drive (ECCD) on m = 2, n = 1 mode stability has been observed because of insufficient values of HF driven current in the vicinity of the q = 2 surface under the operating conditions of the experiment.