Gl. Kuang et G. Waidmann, THE DECISIVE ROLE OF M=1 AND M=2 PERTURBATIONS IN DENSITY LIMIT DISRUPTIONS ON TEXTOR, Acta physica Sinica, 5(1), 1996, pp. 58-70
The behavior of magnetohydrodynamic phenomena associated with disrupti
ons of ohmically heated density limit discharges (q(a) = 3.9) in the T
EXTOR tokamak has been investigated in detail. A minor disruption is d
emonstrated to be only due to an m = 2 mode instability, possibly due
to the magnetic reconnection of an m = 2 island. When the m = 2 mode o
scillations cease, the internal m = 1 kink mode instability is drastic
ally enhanced at once, twisting the plasma core considerably. If the t
wisting is too strong, the twisted plasma core is inevitably displaced
to the outside and brings cold plasma to the central region, leading
to the energy quench at a major disruption.