Optimization of functionally graded materials for plasma facing components by finite element methods

Plasma Facing Components (PFCs) are made of Tungsten, Copper & CuCrZr heat sink, with Copper casting on Tungsten. Due to vast difference in thermal expansion coefficients (15.4*10^-6 to 4.5*10^-6 per⁰ K) between Tungsten and Copper it is proposed to have an interlayer of W/Cu Functionally Graded Material (FGM) between Tungsten and Copper. Present work investigates the effects of the W/Cu Functionally Graded Material (FGM) introduced between Tungsten and Copper interface using finite element method. A representative model problem is formulated to observe different thermal stress characteristics for different compositions of Functionally Graded Material (FGM). Initially a Thermal stress analysis of the model without Functionally Graded Material (FGM) has been performed. A series of Thermal stress simulations (iterations) have been carried out with the introduction of different grades of Functionally Graded Material (FGM) by progressively varying W/Cu compositions. Significant reduction in thermal stresses has been observed at the Tungsten interface region and maximum heat conduction is observed towards Copper. This basic study provides insight into the concept of FGM and lays the foundation of FGM optimisation to control thermal stresses for PFCs.