Rate coefficients for the electron impact excitation of He-like sulfur ions

Abstract

Cross section for the electron impact excitation of S XV is calculated with the use of the R-matrix method. Nineteen lowest LS states are included. Rate coefficients are obtained for the transitions from the ground 1s2 1S state to all the states of 1s2l (l = 0, 1) and 1s3l (l = 0, 1, 2) configurations for the temperature range 1 × 106−1 × 108 K. The resulting effective collision strengths are compared to those reported by Keenan et al. [5]. For the excitation of the n = 3 states, some significant differences are found between the two results.