Electron-impact ionization of Fe14+ and other atomic ions in the Mg isoelectronic sequence

Distorted-wave calculations are carried out for the electron-impact ionizat ion of Fe14+ in both the ground 3s(2) S-1(0) and metastable 3s3p P-3(0,2) l evels. The cross sections and Maxwellian-averaged rate coefficients include direct ionization of the 2s, 2p, 3s, and 3p subshells, as well as inner-sh ell excitations from the 2s and 2p subshells leading to autoionization. The excitation-autoionization contributions are found to be large for both the ground and metastable levels. To assist modeling efforts of moderately den se plasmas, the direct and indirect rate coefficients are resolved as to th e final level of the ionization process and assembled in a standard databas e file. A complete database for selected metallic ions in the Mg isoelectro nic sequence will reside in electronic form at the Controlled Fusion Atomic Data Center at ORNL (http://www-cfadc.phy.ornl.gov/data_and_codes/). (C) 1 998 Elsevier Science B.V.