Molecular Dynamics Simulation Of Extreme Material

The behavior of tungsten as plasma facing material in an extreme environment is investigated using molecular dynamics simulation method. It revealed that the influence of the incident angle of the particles, on the erosion of tungsten surface with the irradiation by plasma impurities. And it also demonstrated that the formation of the surface bubbles, growth, rupture, and microcosmic morphology changes of the tungsten surface.This paper simulates the micro process of the interaction between the impinging CH2group of150eV with different angle and the surface of tungsten. The results showed that the change morphology of the tungsten irradiated surface has a strong dependence on the incident angle of CH2group. When the incident angle is greater than a certain threshold, the kinetic energy of incident particles is greater than its binding energy, most CH2composite particles is reflected out. When the angle is less than the threshold, the combination of W-C bond is very effective, so that the formation of about0.5nm thin W-C layer, and a deposited hydrocarbon thin film on the top of this layer. In almost any incident angles, however, carbon atoms are much more easily to bonded to the tungsten atoms than the hydrogen atoms.This paper also simulates the micro process of the foaming on the tungsten sub-surface by the implantation of helium atoms of the fusion reaction products, with equivalent of60eV. Results show that the formation, growth, rupture of helium bubble in the tungsten sub-surface, lead to the sample surface become rough, looser and thicker, with the basement temperature of1200K. The helium bubble grows along the Z-up. Some of the displacement atoms around helium bubble slip along<111>direction of crystal, to form the face-atoms on the surface. The tungsten atomic layer directly above the helium bubble become thinner with the bubble growth, finally broken up by enough large pressure of helium bubble.