Effect of simulation technique on the high-dose damage in tungsten

Abstract

Tungsten is the material of choice for plasma-facing components planned for fusion reactors. The high irradiation doses accumulated over years of operation from its exposure to high-energy fusion neutrons are expected to alter its microstructure and so degrade its structural properties. In order to understand the defect accumulation on atomistic resolution, computer simulations are a necessity. To reach reactor-relevant doses, overlapping collision cascade simulations can be carried out with Molecular Dynamics, but these simulations are limited by the computationally expensive accumulation of the damage. In this article, we investigate several accelerated methods and compare them to the computationally heavy cumulative accumulation simulations. We find that the acceleration technique chosen can dramatically affect the defect evolution as a function of dose. However, applying ‘cascade annealing’, by adding more collision cascades to configurations generated by the accelerated simulations leads to similar end results for all measured properties, regardless of the technique used to produce the initial damage. This indicates that accelerated simulation techniques can be used to efficiently generate an initial defect population, provided sufficient cascade annealing is subsequently applied.