Towards an improved understanding of the relationship between plasma edge and materials issues in a next-step fusion device

Long pulse lengths, and high power and particle fluxes ensure that the biggest incremental step in a next-step fusion device will be the understanding and control of the plasma–wall interaction region. High confidence, predictive models are needed to bridge the considerable gap from existing devices. Modelling the strong, non-linear feed-back between the plasma and surface physics in this region will require significant improvements in the range and quality of diagnostic information as well as enhanced data on atomic and molecular processes and material properties. This paper highlights the key data required, discusses the need for improved diagnostics to generate these data and examines the case for future, dedicated experiments for studying plasma–wall interactions.