SIII collision strengths

The calculation incorporates 53 fine-structure levels arising from the six configurations--3s^2^3p^2^, 3s3p^3^, 3s^2^3p3d, 3s^2^3p4s, 3s^2^3p4p, and 3s^2^3p4d--giving rise to 1378 individual lines and is undertaken using the recently developed RMATRX II plus FINE95 suite of codes.

A detailed comparison is made with a previous R-matrix calculation and significant differences are found for some transitions. The atomic data are subsequently incorporated into the modeling code CLOUDY to generate line intensities for a range of plasma parameters, with emphasis on allowed ultraviolet extreme-ultraviolet emission lines detected from the Io plasma torus. Electron density-sensitive line ratios are calculated with the present atomic data and compared with those from CHIANTI v7.1, as well as with Io plasma torus spectra obtained by Far-Ultraviolet Spectroscopic Explorer and Extreme-Ultraviolet Explorer.