Temperature and Electron Density Measurements in a DC Glow Discharge

Data on the glow discharge have been accumulated by photographic detection with an echelle spectrometer. Intensity, excitation temperature, and electron density results are reported for the cathode dark space, negative glow, and Faraday dark space regions of the plasma for three values of discharge current and five values of fill gas pressure. It is concluded that neither excitation temperature nor electron density is a useful descriptor of excitation conditions in low pressure plasmas. Excitation is interpreted in terms of an ionization-radiative recombination model, and intensity of argon atomic emission is shown to be correlated with the product of discharge current and argon ionization cross section.