Abstract
The investigation is a sequel to the spectral analysis of Kaufman, Hughes and Williams (1960). From spectrograms taken with the high-current discharge assemblies Sceptre III and IV, new lines of Ne IV, Ne V and Ne VI in the range between about 2200 Å and 3000 Å have been observed and classified. The lists of classified lines and term values, both new and revised, are given in tabular form. No intersystem combinations have been observed in any of the three spectra. A method of distinguishing the higher stages of ionization (Ne IV, Ne V, Ne VI) has been developed by varying the concentration of the neon added to the deuterium. The relative intensities of the spectra vary with the concentration in a characteristic manner and so the lines of a given spectrum can be picked out with comparative ease. A theoretical explanation of the effect is advanced on the assumption that the plasma is cooled by spectral-line radiation. Methods of identifying the stage of ionization when high-current discharges are used as spectral sources are appraised.