High heat flux testing of plasma-facing component mock-ups with tailored tungsten-copper composite heat sinks

Plasma-facing components (PFCs) in future magnetic confinement fusion reactors must sustain high heat fluxes and intense neutron irradiation. These extreme conditions demand specially engineered material solutions. Stateof-the-art designs for highly loaded PFCs are based on bulk tungsten (W) armor combined with a copper (Cu) alloy heat sink. Whereas the monoblock design cannot be readily extrapolated to large dimensions due to the large number of armor blocks, the broader use of the flat-tile design is limited due to concerns about the integrity of the joint of the armor to the heat sink, i.e. the delamination of armor tiles. Therefore, a material design is being explored in which tailored tungsten-copper (W-Cu) composite structures are utilized to minimize thermally induced stresses and to strengthen the bond between a W armor and a Cu based heat sink. These composites are based on W lattice-like preforms, which are additively manufactured utilizing laser-based powder bed fusion (PBF-LB) on monolithic W armor tiles. The composite is created in a vacuum-assisted Cu melt infiltration process. The present work summarizes investigations on two composite specimens with different honeycomb-type W lattice preforms. High heat flux tests were performed in the GLADIS facility to assess the behavior and the thermomechanical response under cyclic heat loading procedures up to 500 pulses at 20 MW m -2 surface heat load. No deterioration in the heat removal capability of the composite heat sinks was found throughout the cyclic tests. Although further optimization of the composite fabrication process is still necessary, the results can be considered a strong hint for the superior performance of the presented PFC concept.