Design and preliminary thermal validation of the WEST actively cooled upper divertor

The WEST (W - for tungsten - Environment in Steady-state Tokamak) project is based on an upgrade of the Tore Supra tokamak, into a double X-point divertor device, while taking advantage of its long discharge capability. Therefore components with tungsten (W) as plasma-facing material will be used. This paper presents the upper divertor of the WEST project (design constraints, thermal performance). This component, with a total surface of 8 m2 is designed to exhaust 4 MW of conducted power in steady state with a maximum local heat load of 8 MW m−2. The actively cooled heat sink of this upper divertor target is made of CuCrZr. It is covered with a W coating up to 30 μm thickness. The suited thermal behaviour of the component was checked using finite element modelling. Moreover, under high heat flux tests this component had the expected thermal exhaust capability and survived without visible damage up to 10.5 MW m−2 in steady-state.