Currents during disruptions

Major disruptions and VDEs result in halo and eddy currents flowing in the conducting structures surrounding plasma [1-4]. These currents can produce unacceptable forces on vacuum vessel and in-vessel components, and their careful evaluation is necessary. Recent analytical theory [5, 6] predicts that the ideal plasma surface current can contribute to the halo, especially when the plasma boundary almost coincides with the rational surface. Here we speculate that such a particular case must not be considered in the frame of the ideal MHD, because it leads to a singularity for the plasma displacement. Treating the cold post-disruption plasma edge as a resistive layer we derive a dispersion relation for the growth rate and mode frequency, expressions for the resistive plasma "surface" current and eddy currents in the wall. Our approach has some similarities with that in [7, 8].