New modeling of scattering behaviors of argon atoms on tungsten substrate

In this study argon beam–tungsten surface scattering processes were investigated numerically by applying molecular dynamics simulations. Energy transfer, momentum change and the scattering processes of argon gas atoms from the W(1 1 0) surface were discussed. The molecular dynamics results showed that Maxwell boundary conditions fail to describe the behaviors of a high mean kinetic energy argon beam impinging on a tungsten surface. A new three-dimensional model of argon–tungsten interaction was thus proposed, and its results proved to be in line with experimental and theoretical results that have been obtained previously by other researchers.Specifically, we developed a method for the normalization of the parameters of a gas beam scattered by a metal surface. We found that the ratio of the average velocity of the scattered beam to the appropriate root mean square deviation (RMSD) allowed us to determine whether the distribution of the scattered atoms was Maxwellian or not. We found that the shape of the functions representing the angular distributions of the scattered Ar atoms could be determined using the ratio of the RMSD of an angle (azimuthal or polar) of the scattered beam to the RMSD of a uniform distribution. The distribution of the azimuthal angle of the scattered atoms was found to be uniform regardless of the incident's kinetic energy, when the incident of the beam on the surface was normal.

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► We have studied argon beam–tungsten surface scattering by molecular-dynamics method.
► We examine energy and momentum change of gas atoms over a wide range on parameters.
► Limited of applicability of Maxwell boundary conditions has been observed.
► New approximation for gas–surface interaction is proposed.