DISTORTED-WAVE CROSS-SECTIONS FOR ELECTRON-IMPACT IONIZATION OF AR7+

Distorted-wave methods have been used to calculate cross sections for electron-impact ionization of sodiumlike Ar7+ for collision energies r anging from near threshold to 1 keV. We included contributions due to excitation-autoionization and resonant excitation-double autoionizatio n (REDA), as well as the contributions from direct ionization of the 3 s electron and the n = 2 inner-shell electrons. We find that the effec ts of radiative damping and loss channels reduce the REDA contribution s by a factor of 4. We compare our calculated results to experimental results and to theoretical cross sections obtained in a close-coupling approximation.