Technologies for the ITER divertor vertical target plasma facing components

The ITER divertor vertical target (VT) has to sustain heat fluxes up to 20 MW/m2. The concept developed for this Plasma Facing Component (PFC) working at steady state is based on Carbon Fibre Composite (CFC) armour for the lower straight part and tungsten (W) for the curved upper part. The main challenges of such components are to be able to remove the high deposited heat fluxes and to join mechanically and thermally armour to the metallic heat sink, despite of the mismatch of the thermal expansions. Two solutions based on the use of CuCrZr hardened copper alloy and active metal casting (AMC) process were investigated during the ITER EDA phase: the first one called 'flat tile geometry' was mainly developed for Tore Supra pumped limiter, the second one called 'monoblock geometry' was developed by the EU Participating Team for the ITER project. This paper presents a review of these two solutions and analyses their assets and drawbacks: pressure drop, critical heat flux, surface temperature and expected behaviour during operation, risks during the manufacture, controls of the armour defects during the manufacture and at the reception and possibility to repair defected tiles. (author)