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Relative population densities and transition probabilities in a neon glow discharge Irwin, John Charles


An experimental technique has been developed for the investigation of departures from thermodynamic equilibrium in plasmas. The relative populations of the upper and lower levels of a spectral line are measured by the reversal temperature method. The reversal temperatures themselves are determined by varying the relative exposure times of the background source and the plasma to be investigated. The relative population densities of the levels in the 2p⁵3s and 2p⁵3p configurations of Nel have been measured. A Neon glow discharge operated in the current region 1mA to 100mA served as the plasma. The results show that the excited gas is definitely not in thermal equilibrium. The relative intensities of the emission lines between the 2p⁵3s and 2p⁵3p configurations of NeI were measured photometrically and corrected for self-absorption. These intensities were then used in conjunction with the relative population densities to determine relative transition probabilities for the spectral lines concerned. The results are accurate to approximately 10% to 15% and are compared to the values obtained previously by other workers.

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