Infoscience

Conference paper

Plasma radiation distribution and radiation loads onto the vessel during transient events in JET

The JET bolometer camera system allows greatly improved tomographic reconstruction of the radiation pattern on a timescale of the order of the typical duration of a Type I ELM period (approximate to 0.1-0.4 ms). The ELM-induced radiation is always higher at the inner than at the outer divertor with an approximately linear increase of the asymmetry up to a total Delta W-ELM of about 0.6 MJ and a decrease for higher Delta W-ELM. Large Type I ELMs with energy losses above 0.65-0.7 MJ show enhanced radiation losses, which are associated with the ablation of thick co-deposited layers in the inner divertor. During the 'compound' phase, plasma contamination can increase but does not usually lead to radiative collapse of the plasma. It is found that the radiation distribution during the transient events is poloidally asymmetric with a maximum of the observed 'radiation peaking factor' for the disruptive current quench and for MARFEs of about 4.5, and less than 5 during VDEs. (C) 2009 Elsevier B.V. All rights reserved.

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