Scaling relation for total excitation cross sections of He in collisions with highly charged ions

Abstract

Total cross sections for excitation of He singlet levels by highly charged ions of charge states q from 3 to 45, and for projectile velocities from 1.6 to 7.5 a.u., were measured. A scaling of cross section per q with specific energy per q was observed, and is discussed on the basis of classical arguments. In addition to their fundamental aspect, the measurements are important for the prospects of neutral-beam injection heating and beam-driven currents in tokamaks.