Thermal load distribution on the ALT-II limiter of TEXTOR-94 during disruptions

Disruptions investigated on TEXTOR-94 are initiated by unstably growing modes. The island width of these modes corresponds to 5-10 cm resulting in a perturbation field amplitude of the order of 100 Gauss, The energy stored in the plasma is released in short and intense power fluxes towards the limiter, the power decay length is practically unchanged with respect to the normal power e-folding length. These observations can be interpreted in the following way: The perturbation fields associated with the modes create an ergodization of the full plasma cross-section creating a laminar zone with convective fluxes at the plasma edge. The energy transport inside the plasma is determined by the ergodic transport while the power flux to the limiter is convective. The assumption of the ergodization has important consequences for runaway electron level created during disruptions. (C) 2001 Elsevier Science B.V. All rights reserved.