JET Disruption Studies in Support of ITER

Plasma disruptions affect plasma facing and structural components of tokamaks due to electromechanical forces, thermal loads and generation of high energy runaway electrons. Asymmetries in poloidal halo and toroidal plasma current can now be routinely measured in four positions 90o apart. Their assessment is used to validate the design of the ITER vessel support system and its in-vessel components. The challenge of disruption thermal loads comes from both the short duration over which a large energy has to be lost and the potential for asymmetries. The focus of this paper will be on localised heat loads. Resonant magnetic perturbations failed to reduce the generation of runaway electrons in JET. An explanation of the limitations applying to these attempts is offered together with a minimum guideline. The REs generated by a moderate, but fast, Ar injection in limiter plasmas show evidence of milder and more efficient losses due to the high Ar background density.
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