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P: Plasmaphysik

P 1: Magnetic Confinement and Plasma Wall Interaction

P 1.1: Talk

Monday, April 2, 2001, 16:30–16:45, 2053

Mitigation of the effects of disruptions in the tokamak TEXTOR-94 — •G. Mank, K.H. Finken, A. Krämer-Flecken, S.S. Abdullaev, G. Fuchs, and A. Savtchkov — Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Ass., 52425 Jülich, Germany

The serious consequences of a sudden energy quench in a fusion plasma can be mitigated by the injection of impurities into the collapsing plasma. At TEXTOR a fast massive helium gas puff (about 1 mbar L/ms) has been used to influence the plasma current decay time. By this method no strong additional heat pulses during the decay phase appear. The injection of helium allows the rapid suppression of runaway electrons which can be produced after the thermal energy quench. Further no strong wall loading is observed, thus reducing the necessity to perform a glow discharge to deplete the wall. The injection of a gases for the termination of a discharge allows to influence the collapse of the plasma even if the plasma column is displaced. Fast mode detection systems make it possible to inject helium during growing mode activity (e.g. m=2) or to suppress the mode and by this the disruption by neutral beam injection.