Response of plasma facing components to off-normal heat loads in a next generation nuclear fusion device

Abstract

During off-normal events, especially disruptions and runaway-electron impact, the plasma facing components of a tokamak are subjected to high heat loads. In the case of a next generation device the large increase of the stored energy will lead to energy deposition values which will very much exceed those experienced in present day devices. For this reason the behaviour of plasma facing materials and components under high heat fluxes needs study to arrive at sufficiently reliable predictions of their response to off-normal events. However, until now only partially quantitative predictions have been possible. This deficiency is mainly due to the lack of knowledge of the actual processes which occur during off-normal events in tokamaks. In addition, experiments and numerical approaches can simulate only partial aspects of these complex processes. The present knowledge of the response of the plasma facing components of a next generation device to off-normal heat loads is summarized.