Interferometric measurements of the gas density distribution in the dark space of an abnormal glow discharge in xenon

Abstract

Measurements of the spatial dependence of the gas density distribution near the cathode of an abnormal glow discharge on the current density are described. The technique uses a pulsed discharge in xenon with a mercury cathode, placed in one arm of a Michelson interferometer so that the changing density influences the optical path length. The sensitivity of the system is equivalent to approximately 0.04 Torr at 300K. Considerable changes in gas density are observed in the dark space, particularly at high current densities. The proposed theoretical model for this non-uniform gas density agrees well with the experimental results.