Design optimization of plasma facing component with functional gradient material Cu/W interlayer

In the current water cooled divertor concept, tungsten is an armor material and CuCrZr is a structural material. The difference in thermal expansion coefficient between tungsten and copper alloy causes a thermal mismatch between them resulting in accumulation of stresses which would yield failure of the joint. To reduce such stresses, a functionally graded material or a graded layer is introduced between tungsten and copper alloy. A fabrication via a powder metallurgy process such as SPS (Spark Plasma Sintering) is proposed. In this work, an actively cooled component composed of a functionally graded W/Cu is simulated under high heat flux using the finite element modeling method. Thermo-mechanical behaviors, due to the existence of temperature gradient, are analyzed by a modification of the layer compositions and the number of layers. Such behaviors are evaluated to determine the optimal water cooled divertor design. It appears that the copper concentration in the interlayer defines the mechanical response. We suggest, as a conclusion, to use three layers having an optimized copper concentration to fabricate them using SPS technology.