PHENOMENOLOGY OF MAJOR AND MINOR DISRUPTIONS IN HIGH-BETA DEUTERIUM AND TRITIUM TOKAMAK FUSION TEST REACTOR PLASMA

The main subject of this work is the experimental study of the low m a nd n magnetohydrodynamics (MHD) perturbations during disruptive instab ility. This work presents the magnetic probe data, electron cyclotron emission (ECE), alpha-particle losses, and neutron flux data measured during the disruptive instability in high beta tokamak fusion test rea ctor (TFTR) [D. J. Grove and D. M. Meade, Nucl. Fusion 25, 1167 (1985) ] plasmas. The major disruptions in high beta regimes go through sever al phases. The first phase is the fast (150-250 mu s) minor disruption (predisruption), causing a drop of the central temperature (and possi bly, density). In this phase a powerful central m=1/n=1 mode initiates the sequential development of m=4/n=1, 3/1, 2/1, 3/2 peripheral modes , which lead to a 3/1 locked mode. The second phase is the slow therma l quench (2 ms) in the presence of a locked mode. The third phase is a fast positive current spike generation (5%-10% increase in Ip in less than 0.5 ms) and finally, the current quench occurs with a loss of 2. 5 MA in 5 ms. (C) 1998 American Institute of Physics. [S1070-664X(98)0 0911-2].