Electron-impact single and double ionization of the Fe atom and Feq plus (q=1-4) atomic ions

Electron-impact single and double ionization cross sections for the Fe atom and Feq+(q= 1-4) atomic ions are calculated using a combination of perturbative distorted-wave (DW) and non-perturbative time-dependent close-coupling (TDCC) methods. The single ionization cross sections include contributions from outer subshell direct ionization and excitation-autoionization. The double ionization cross sections include contributions from direct double ionization, inner subshell direct ionization, and excitation-autoionization. The accuracy of the perturbative DW calculations for direct ionization of the outer subshells of Fe and Fe+ are checked by comparison with non-perturbative TDCC calculations. The cross sections for single and double ionization are then compared with crossed-beams measurements.