ON THE ASYMPTOTIC-BEHAVIOR OF ELECTRON-IMPACT IONIZATION CROSS-SECTIONS

Behavior of the ionization cross sections at high incident electron en ergies E >> I was considered, where I is the binding energy of the tar get. Presenting the total ionization cross section as a sum of the cla ssical and dipole (Bethe), terms the dependences of the ionization cro ss sections on the principal and orbital quantum numbers of the target are investigated. The applicability of the asymptotic formulas obtain ed is discussed on the basis of comparison with ionization cross secti ons calculated in the Born approximation for high n states.