A unified theory of Stark broadening for hydrogenic ions—III: Results for He II Lyman-α

Calculations have been performed for He II Lyman-α using a previously developed theory (Papers I and II in this series) in which the effect of time-ordering in the required time development operator is retained. Representative results are given for an electron density of 10¹⁷ cm^-3 and a temperature of 40,000°K. Compared with non-time ordered results, these profiles are about 17% lower at line center and up to 16% higher in the wings. In addition, since the perturbing electron is speeded up by the Coulomb attraction, in comparison with neutral hydrogen the static results are not obtained until much further into the line wings. Comparison is also made to the calculations of Kepple for which good agreement is obtained, except near the line center where the difference approaches 25%.