Strike-point splitting induced by external magnetic perturbations: Observations on JET and MAST and associated modelling

Heat flux deposition profiles, calculated from infrared imaging, are presented for JET and MAST cases in the presence of external magnetic perturbations. In L-mode, a clear splitting of the strike-point is observed and well reproduced by modelling based on field line tracing with no plasma magnetic response included (vacuum field approximation). In H-mode, in contrast, the splitting is not clearly observed in spite of being expected from vacuum field modelling. As illustrated by modelling results, screening effects could explain the absence of a clear splitting in H-mode. (C) 2010 Elsevier B.V. All rights reserved.