Theoretical study of image charge acceleration of highly charged ions in front of a metal surface

Abstract

We show how a simple model for electron transfer from a metal surface to a slow highly charged ion can be used to calculate the image charge interaction energy. In the theoretical model the attractive force, caused by the image charge, is described with a classical image potential. The velocity of the ion enters explicitly and the electron transition rate has an exponential decay with the distance from the surface. The distance where the rate of change of the ion charge has a maximum is required to fulfil a classical barrier condition. The results compare reasonably well with recent experiments for ions with charges up to q ≈ 80.