Observation of Ion Motion in Hydrogen Stark Profiles

Abstract

We have measured the central part of the Balmer ${\mathrm{H}}_{\ensuremath{\beta}}$ or ${\mathrm{D}}_{\ensuremath{\beta}}$ line in similar stabilized arc plasmas, but of different chemical compositions. We have found an ion-motion effect which appears to scale with the inverse square root of the reduced mass of the radiator-perturber system and which, for ${\mathrm{H}}_{\ensuremath{\beta}}$ at least, essentially removes one of the largest remaining discrepancies between experiment and Stark-broadening theory.