A better nanochannel tungsten film in releasing helium atoms

Discovering highly radiation resistant plasma facing materials (PFM) is an urgent target for nuclear fusion reactor. In our previous work, a new PFM (nanochannel tungsten film) that consists of many tungsten crystal columns was found having excellent radiation tolerant properties. In the present work, three tungsten columns whose top surfaces are {100}, {110} and {111} -oriented were studied by molecular dynamics simulations and density functional theory calculations. We find that the tungsten columns whose top surfaces are {100}-oriented retain fewer helium atoms than the tungsten columns whose top surfaces are {110} or {111}-oriented. Moreover, the microstructural changes of tungsten columns whose top surfaces are {100}-oriented are smaller than others after high helium fluence exposure, which indicates that the nanochannel tungsten film maybe more suitable than bulk tungsten for plasma facing material in releasing helium atoms and delaying the formation of “fuzz” structure. The results reported here can help us to design a better radiation resistant plasma facing material in the future.