Double electron transitions in collisions between multiply charged ions and helium atoms

Abstract
A semiclassical model for He is applied to the study of multiply charged ions colliding with He at intermediate energies. Single and double-electron capture and ionisation and capture-ionisation reactions are studied for incident-ion charge states q=+1 to +50 at 1 MeV amu-1. For charge states q>or approximately=+10, single electron capture is found to be dominated by a two-electron transition in which one electron is captured and the other is ionised.