MeV Cluster Ion Beam–Material Interaction

Abstract

This paper treats the characteristic topics of MeV/atom cluster ion beams produced using tandem accelerators both in the production stage and in the penetration stage from the viewpoint of fundamental processes. The former is related to atomic collisions in that production and decay of a cluster ion Cn+ (n=1−4) colliding with a charge-changing rare gas underlined through the electron-loss process. Regarding the latter, relatively small carbon clusters Cn+ (n=2−10) are treated. The reduction effect of the average charge of cluster ions in a material is first presented. Next, the electronic stopping power and the energy loss, the polarization force, and the coulomb explosion under cluster-ion impact are described in the dielectric function form. Alignment and structure effects are stressed. As a large and highly symmetric cluster, the electronic stopping power and the average charge are shown for a C60 cluster ion moving inside a solid. Throughout the paper, it is emphasized that the vicinage effect originating from correlation on spatial structure and orientation of constituent ions plays the key role. Moreover, results obtained in cluster production and penetration phenomena are mostly different from multiplication of those under single-ion impact.