COUPLING OF INTERNAL M=1 AND M=2 MODES AT DENSITY LIMIT DISRUPTIONS IN THE T-10 TOKAMAK

A soft X ray imaging system consisting of three arrays of silicon surf ace barrier diodes is applied to the tomographic analysis of internal Plasma perturbations in the T-10 tokamak (R0 = 1.5 m, a = 0.32 m). It is found that density limit disruptions in a plasma with a high safety factor at the edge (q(a) = 3.5-4.5) are associated with joint rotatio n of the m = 2, n = 1 and m = 1, n = 1 modes, overlapping at the energ y quench stage. Electron cyclotron resonance heating is used to preven t density limit disruptions or to recover stable operation of the disc harge after the energy quench at the density limit.