Charge Equilibrium Fractions of a Helium Beam in Hydrogen, Nitrogen, Neon, and Argon from 60 to 850 keV

Equilibrium fractions of charge 0, +1, and +2 of helium beams traversing the gas targets H₂, N₂, Ne, and Ar have been measured. Primary beams of (He⁴)⁺ and (He³)⁺⁺ were used. The measurements cover ion velocities corresponding to energies of (He⁴)⁺ between 60 to 850 keV. The charge-equilibrated beam was magnetically separated and charge spectra were recorded by means of a movable detector of equal sensitivity for all three charge components. In the energy interval of overlap, that is between 60 and 200 keV, agreement with Barnett et al. is excellent in the fractions F_0∞ and F_1∞, which make up almost the entire charge-equilibrated beam. The results show a strong dependence of the equilibrium charge distributions on the chemical nature or electronic configuration of the gas target.