Measurement and Calculation of the Stark-Broadening Parameters for the Resonance Lines of Singly Ionized Calcium and Magnesium

Abstract

The electron-impact-broadened profiles of the resonance lines of singly ionized calcium ($\lambda \sim 3934$ Å) and magnesium ($\lambda \sim 2802$ Å) have been measured using an electromagnetically driven shock tube and a rapid-scanning Fabry-Perot spectrometer. For $N_e\simeq {10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and $T\simeq 19000°$K, we found the Lorentizian half-width of the ${\mathrm{Ca}}^{+}$ line to be 0.086 Å ± 10% and of the ${\mathrm{Mg}}^{+}$ line to be 0.044 Å ± 10%. Using the quantum-mechanical theory of Barnes and Peach and our semiclassical calculation for the calcium lines, we found that the temperature dependence of the theoretical curves is close to that measured, although both theories predict actual values which are somewhat large. Using the quantum-mechanical theory of Bely and Griem and our semiclassical calculation for the magnesium lines, once again we found that the shape of both curves agrees quite well with the experimental points, although the quantum-mechanical predictions are somewhat too small. The probable sources of error are the use of the classical assumption in the semiclassical calculations and the use of an incomplete set of perturbing levels in the quantum-mechanical calculations.