METHOD FOR CALCULATING THE ELECTRON-IMPACT IONIZATION OF IONS OF ANY COMPLEXITY

Relativistic,distorted-wave cross sections are calculated for electron -impact ionization from the 21 subshells with n = 3, 4, and 5 in sever al types of ions. Based on these results and the general, but very sim ple form for the cross section derived by Sampson and Zhang [Phys. Rev . A 45, 1657 (1992)] a very rapid, but quite accurate method using fit s to the reduced cross sections is given. This applies to highly charg ed ions with any degree of complexity and should be very convenient fo r use in plasma modeling. The procedure is illustrated by application to inner-shell ionization of Cu-like gold ions, where good agreement i s obtained with detailed direct relativistic distorted-wave calculatio ns.