ATOMIC DATA AND SPECTRAL-LINE INTENSITIES FOR C-LIKE SI-IX

Electron impact collision strengths and spontaneous radiative decay rates are calculated for the C-like ion, Si IX. The data pertain to the 46 levels of the configurations 2s22p2, 2s2p2, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d. Collision strengths are calculated at three incident electron energies: 20.0, 40.0 and 60.0 Ry. Spectral line intensities are calculated for all transitions with intensities within two orders of magnitude of the most intense Si IX line. These are obtained by computing the excitation rate coefficients, that is, the collision strengths integrated over a Maxwellian electron distribution, and then solving the equations of detailed balance for the populations of the 46 energy levels, assuming a collisional excitation model and an electron temperature of 1.26 × 106 K. This temperature is typical for Si IX in solar and some other astrophysical plasmas. Using the excitation rate coefficients and the radiative decay rates, level populations are computed for several electron densities and are also given in this paper. © 1993 Academic Press. All rights reserved.