Atomic-scale modeling toward enabling models of surface nanostructure formation in plasma-facing materials

Publication date: March 2019Source: Current Opinion in Chemical Engineering, Volume 23Author(s): Dimitrios Maroudas, Brian D WirthDesigning plasma-facing components (PFCs) that can tolerate the extreme heat and particle flux exposure conditions inside a fusion reactor core is one of the major obstacles toward the practical realization of nuclear fusion. In this article, atomic-scale simulation findings are reviewed that provide a fundamental understanding of the dynamical response of tungsten, an important PFC material, to reactor-relevant plasma exposure conditions leading to helium implantation. This hierarchy of simulations include molecular-statics computations to establish helium-surface interaction energetics and the origin of helium segregation on tungsten surfaces, targeted molecular-dynamics (MD) simulations of near-surface helium cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten conducted in leadership-scale computing facilities. The simulations reveal that cluster-surface elastic interactions induce drift fluxes of small mobile helium clusters in the tungsten toward the plasma-exposed tungsten surface, which facilitate helium segregation on the surface and activate cluster reactions, most importantly trap mutation, which generates a flux of self-interstitial tungsten atoms to the surface. Such near-surface cluster dynamics has significant effects on PFC surface morphological evolution, near-surface defect str...
Source: Current Opinion in Chemical Engineering - Category: Chemistry Source Type: research