Atomic data and spectral line intensities for Ca XIV

Abstract

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ca XIV. The configurations used are 2s 22p 3, 2s2p 4, 2p 5, 2s 22p 23s, 2s 22p 23p, 2s 22p 23d, and 2s2p 33s giving rise to 91 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies: 45, 90, 135, 180, and 225 Ry. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8–10 14 cm −3 at an electron temperature of log T e (K) = 6.5, corresponding to a maximum abundance of Ca XIV. Relative and absolute spectral line intensities are calculated and compared with observations of a solar active region and of tokamak plasma.