A Bulk Tungsten Tile for JET: Derivation of Power-Handling Performance and Validation of the Thermal Model, in the MARION Facility
In the frame of the ITER-Like Wall (ILW) for the JET tokamak, a divertor row made of bulk tungsten material has been developed for the position where the outer strike point is located in most of the foreseen plasma configurations. In the absence of active cooling, this represents a formidable challenge when one considers the temperature reached by tungsten (TW,surf >2000°C) and the vertical gradient ðT/ðz = 5¥104 K/m. As the development is drawing to an end and most components are in production, actual 1:1 prototypes are exposed to an ion beam with a power density around 7MW/m2 on the plasmafacing surface. Advantage is taken of the flexibility of the MARION facility to bombard the tungsten stack under shallow angles of incidence (~6°) with a powerful beam of ions and neutrals (>70MW/m2 on axis). It does help in validating the thermal model that was steadily developed along with the tungsten tile and delivers, with respect to the toroidal wetted surface, experimental values to the expected performance under actual tokamak conditions.