Measurements of cross sections for inelastic collisions between 4He+ ions

Cross sections for He2+ production and charge transfer have been measured for collisions between two unexcited He2+ ions at centre-of-mass energies between 14 and 58 keV. In this range the cross section for He2+ production rose with increasing energy from 5.3 x 10-18cm2 to 24 x 10-18cm2, whilst the cross section for charge transfer increased from 5.2 x 10-18cm2 to about 19 x 10-18cm2. The measurements of charge transfer were compared with theoretical and experimental results for He(1s2) + He2+ → He+(1s) + He+(1s). Excellent agreement was found which implies that, for interactions between 4He+ ions at these energies, charge transfer proceeds almost exclusively into the ground state. (author)