Monte Carlo simulations of pure tungsten and advanced “smart” tungsten alloys under helium bombardment for future fusion power plants

Abstract

Self‐passivating tungsten‐based alloys may provide a major safety advantage in comparison with pure tungsten, which is presently the main candidate material for the plasma‐facing protection of future fusion power reactors. Advanced “smart” tungsten‐based alloys adjust their properties to the environment: during the plasma operation, preferential sputtering will form almost pure tungsten surface facing the plasma. In case of an accident, the remaining alloying elements form a protective layer, preventing tungsten mobilization. The major challenge in such a scenario is to suppress the sublimation which is responsible for a release of radioactivity. Subsequent oxidation confirmed superior oxidation resistance that is to say resistance to sputtering of advanced “smart” tungsten‐based alloys compared with pure tungsten (W). In this work, we study an alloy containing tungsten (W), chromium (Cr), silicon (Si), titanium (Ti), and yttrium (Y). We have applied the Monte Carlo SRIM‐2013 simulation program to calculate the sputtering yields, number of vacancies, and backscattering yields of the first wall of pure tungsten (W) and advances “smart” tungsten‐based alloys (W‐Cr, W‐Si, W‐Cr‐Si, W‐Cr‐Ti, and W‐Cr‐Y) by helium ion bombardment. It is found that the sputtering yields of advanced “smart” tungsten alloys are very low than that of pure (W) at each incident energy and incidence angle. On the other hand, the sputtering yield depends on the properties of both the incident particle and the target.