Light emission from the cathode zone of DC glow discharge

Abstract

The space close to a cathode of a low-pressure glow discharge (∼15Pa) is a reservoir of sputtered atoms in the gaseous phase and that seems to be an effective source of optical lines of buffer gas as well as those of sputtered solid. The dependence of line intensity on discharge parameters (gas pressure, current density) are well qualitatively explained by the phenomenological modelling, where characteristics (e.g. cross sections of particle–particle and particle–solid interaction, energy spectra of fast heavy molecules) of fundamental processes are taken into account for both buffer gas and sputtered species. Agreement of experimental results with those of modelling allows to conclude that fast heavy molecule–buffer gas or sputtered material interaction is the main excitation channel. Excitation in the cathode solid and non-radiative electron transfer seem to be second-rate processes affecting the sputtered material luminescence.