Strain and thermal gradient effects on the transport properties of intrinsic defects and impurities in tungsten

Plasma-facing materials (PFMs) in a fusion reactor are expected to withstand stringent conditions, with high heat and particle fluxes that create strong gradients of temperature and concentration of diverse species. These species will then migrate in the presence of the afore-mentioned gradients and large strain fields. In this work, we use nonequilibrium molecular dynamics (NEMD) simulations to study the transport properties of H, He, and SIAs in the presence of a thermal gradient and different strain fields in tungsten. The NEMD simulations reveal that defects and impurity atoms tend to migrate toward the hot regions of the material (negative heat of transport). The resulting concentration profiles are in agreement with the predictions of irreversible thermodynamics. Furthermore, strain seems to play a critical role in the transport of these species significantly changing the concentration profiles. We demonstrate that the resulting steady-state profiles significantly depend on these fields.