Modelling of power exhaust in fusion plasmas

This PhD thesis deals with the thorny problem of †œModelling of power exhaust in fusion plasmas†�, a challenge concerning the development of a system able to withstand the large loads expected in the fusion power plant divertor. After an introduction to fusion and to the key concepts modelling the behaviour of the plasma during plasma-surface interactions and describing the power exhaust, an overview of the state-of-the-art in the research field on power exhaust is given. A brief introduction on theoretical basis of the plasma boundary reconstruction precedes the author first contribution in the design and vertical stability analysis of plasma alternative magnetic configurations for a demonstration fusion power plant (DEMO). The second contribution concerns an assessment of the DEMO divertor target tiles lifetime in case of strike-point sweeping. This technique is one of the most promising candidate solution to the power exhaust issue but its main drawback is related to the periodical heating and cooling of the plasma facing components inducing the thermal-fatigue phenomenon. To evaluate the lifetime of the DEMO divertor target tiles, different 2D and 3D thermo-mechanical models are presented. Finally, a preliminary analysis on the wobbling technique applied to a DEMO Double Null plasma magnetic configuration is illustrated.