Damage effects of high-intensity laser pulse on W for fusion applications: modelling and experiments

In future nuclear fusion reactors plasma-facing materials (PFMs) will be exposed to transient high energy events such as disruptions, edge localized modes (ELMs) and vertical displacement events (VDEs) which may cause melting and vaporization leading to component damage and plasma contamination. The interaction between plasma and refractory metals, namely bulk tungsten (W) and W deposited by plasma spraying (PS-W), has been simulated through a single laser pulse of high energy (≈ 4 J) and short duration (≈ 15 ns). The morphology of the zone affected by laser pulse has been then examined by scanning electron microscopy (SEM) and 3D optical surface profilometry. Both an analytical and a numerical thermal model of the phenomenon based on the specific conditions of heat transfer from the laser spot into each irradiated material were developed. The attention has been focused on the erosion occurring on the material surface because this is the primary cause of damage of PFMs and plasma contamination. Numerical, analytical, and experimental results were found in good agreement.