On the formation of surface craters by rapid cluster ions

Abstract

A theoretical approach is developed to describe the dominant features of process by which craters form on the copper, gold and solid argon surfaces under self impacts of high velocity cluster ions. It is showed that, in the shock wave conditions generated at the impact of cluster on the surface, the dynamical process begins when the shock reaches the target free surface inducing the formation of a rarefaction wave(release wave) which propagates inward into the compressed region. The rarefaction causes the shocked material to move toward the free surface and expand into a vacuum forming the crater. It is found that the size of cluster has a significant influence on the mechanism of crater formation. In addition to metals (Cu and Au) the proposed approach has been successfully extended to impact of argon clusters on solid argon substrate. The approach has been validated using molecular dynamics simulated data for copper, gold and argon available in the literature. All simulated crater volumes have been analytically reproduced with a good agreement on the basis of a hemispherical shape.