Improved Stark Profile Calculations for the Hydrogen Lines Hα, Hβ, Hγ, and Hδ

Abstract

The frequency distributions of the first four Balmer lines broadened by the local fields of both ions and electrons in a plasma are calculated in the classical path approximation. The electron collisions are treated by an impact theory accounting for upper- and lower-level perturbations and allowing (approximately) for level splittings caused by the ion fields, finite duration of the collisions, and screening of the electron fields. Ion effects are calculated in the quasistatic, linear Stark-effect approximation, using Hooper's distribution functions, which include correlation and shielding effects to high orders. Theoretical uncertainties (mainly from the impact approximation) generally increase with density, frequency separation from the line center, and decreasing temperature. However, they only exceed ∼10% when a substantial fraction of the electrons begins to act quasistatically, and agreement with measured linewidths is within 10% in all cases.