Description
Spectral lines of He-like ions are among the most prominent features in X-ray spectra from a large variety of astrophysical and high-temperature fusion plasmas. A reliable plasma modeling and interpretation of the spectra require a large amount of accurate atomic data related to various physical processes. In this paper, we focus on the electron-impact excitation (EIE) process. We adopted the independent process and isolated resonances approximation using distorted waves (IPIRDW). Resonant stabilizing transitions and decays to lower-lying autoionizing levels from the resonances are included as radiative damping. To verify the applicability of the IPIRDW approximation, an independent Dirac R-matrix calculation was also performed. The two sets of results show excellent agreement. We report electron impact excitation collision strengths for transitions among the lowest 49 levels of the 1snl(n<=5,l<=(n-1)) configurations in He-like ions with 20<=Z<=42. The line ratios R and G are calculated for Fe XXV and Kr XXXV.
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