Spectroscopic Investigation of a Hydrogen and Helium Plasma in a P.I.G. Discharge

Abstract

The intensities of spectral lines emitted from a low pressure P. I. G. discharge running in hydrogen and helium gas have been measured, and the population densities of the corresponding excited levels have been calculated from there. It was found that the population densities of the excited states do not follow the values given by the SAHA equation. The probable reason for this deviation is the influx (or diffusion) of the neutral atoms into the plasma column. A model which takes into account the free diffusion of the surrounding gas atoms into the plasma column permits an explanation of the observed phenomena. Using this model and solving the corresponding rate equations, electron temperatures of several electronvolts have been obtained for both gases. These temperatures are confirmed by mass spectrometric abundance measurements of the He⁺- and He²⁺-ions, in conjunction with the coronal ionization formula.