Power handling of a segmented bulk W tile for JET under realistic plasma scenarios

摘要

A solid tungsten divertor row has been designed for JET in the frame of the ITER-like Wall project (ILW). The plasma-facing tiles are segmented in four stacks of tungsten lamellae oriented in the toroidal direction. Earlier estimations of the expected tile performance were carried out mostly for engineering purposes, to compare the permissible heat load with the power density of 7 MW/m~2 originally specified for the ILW as a uniform load for 10 s. The global thermal model developed for the W modules delivers results for more realistic plasma footprints: the poloidal extension of the outer strike point was reduced from the full lamella width of 62 mm to ≥15 mm. Model validation is given by the experimental exposure of a 1:1 prototype stack in the ion beam facility MARION (incidence ～6°, load E ≤ 66 MJ/m ~2 on the wetted surface). Spreading the deposited energy by appropriate sweeping over one or several stacks in the torus is beneficial for the tungsten lamellae and for the support structure.