An analytic Voigt profile escape probability approximation

An efficient analytic Voigt profile escape probability approximation is presented and compared to exact numerical calculations. Using this analytic approximation, the two-level-atom source function is also computed for optically thick media, which have been previously evaluated exactly by Avrett and Hummer. Comparison with a more realistic laboratory plasma case also validates the usefulness of the approximation for economical modeling of radiation transport in optically thick plasmas.