Resonance contribution to electron-impact excitation of Ne-like ions.

Abstract

Detailed calculation of cross sections and rate coefficients for electron-impact excitation of Ne-like ions is presented in which contributions of the resonance intermediate states, 2p/sup 5/n/sub t/l/sub t/nl with n/sub t/less than or equal to4, are included, leading to the final states 2p/sup 5/3l/sub f/, where l/sub f/ = 0,1,2. The cascade effect greatly complicates the calculation, as compared with the complementary process, the dielectronic recombination. The present study of the Fe/sup 16+/ ion supplements the earlier work by B. W. Smith et al. (Astrophys. J. 298, 898 (1985)), while the Se/sup 24+/ ion was considered in detail for application to soft x-ray lasers. The resonance-excitation effect reduces substantially the existing discrepancy in the case of Se between the simple ionization-balance model and recent plasma experiments.