CROSS-SECTIONS FOR HYDROGEN AND HELIUM IONIZATION BY IMPACTS OF FAST HIGHLY-CHARGED IONS

Collisions of hydrogen and helium atoms with fast highly charged ions are considered for the range of parameters upsilon less than or simila r to Z << gamma upsilon(2) tau, upsilon >> upsilon(0) (Z and upsilon a re the ion charge and velocity, respectively; upsilon(0) is the orbita l velocity of atomic electrons; tau is a characteristic atomic time; g amma = (1 - upsilon(2)/c(2))(-1/2), c is the speed of light). Formulae have been derived for cross sections of hydrogen and helium (single a nd double) ionization. A formula has also been obtained for cross sect ions of hydrogen excitation into discrete states.