GEOMETRY FREE OF SINGULARITIES FOR FUSION DUPLEX COMPONENTS

Duplex components are one of the proposed concepts for actively cooled plasma-facing structures. This concept introduces a new source of str esses due to the mismatch in the coefficients of thermal expansion bet ween the bounded materials. To ensure equilibrium, singular edge stres ses fields are generated at the edge with high values of the involved gradients. Although confined to a very small region, their characteris ation is important because debonding starting from this region is one common cause of component failure. Castellated beryllium tiles brazed to a copper alloy (CuCrZr) heat sink has been studied as prototype tar get plates for the pumped divertor phase of JET. For this system, an e igenvalue analysis is performed for edge stress fields free of singula rities and favourable local geometry is deduced. Based on these result s, guidelines for component optimisation with respect to those fields are presented. In particular the strong effect of the local geometry i s discussed.