Analysis of radiative disruptions in RF-heated Tore Supra plasmas using infrared imaging

The precursors and following sequential events leading to radiative disruptions in Tore Supra have been analysed using infrared imaging, together with visible and ultraviolet spectroscopy of impurity species. A common feature observed prior to the disruptions is the appearance of a small (similar to cm(2)) hot spot on the main plasma facing component, the Toroidal Pumped Limiter (TPL), clearly localised in a Zone of thick carbon re-deposition (> 100 mu m). A MARFE (Multifaceted Asymmetric Radiation From the Edge) is often triggered, followed by disruption. Such hot spots have been observed in similar to 24% of the analysed disruptions, which is consistent with the fact that only 4/18 (22%) of the total area of the TPL is monitored with infrared cameras. These results suggest that over-heating of thick carbon re-deposition layers may play a role in the operational limits (MARFE, disruption) encountered. (C) 2009 Elsevier B.V. All rights reserved.