Rotational and vibrational temperature distributions in cathode fall region of Grimm glow discharge

Abstract

Optical emission spectroscopy technique is used to measure rotational and vibrational temperature along the axis of cylindrical abnormal glow discharge parallel to the copper cathode surface (side-on) in hydrogen-argon mixture at low pressure. The rotational temperature of excited state of H2 was determined from the rotational structure of Q branch of Fulcher-α diagonal band using Boltzmann plot technique. From the intensity ratio of two consecutive vibrational bands of the same sequence, the H2 (d3Πu) vibrational temperature is determined. The population of excited energy levels, determined from relative line intensities, was used to derive rotational and vibrational temperature distributions in cathode fall region as well as relative population densities of vibrational levels of the d3Πu.