=The line profile of the HeI line at λ447.15 nm has been measured during the ionisation phase and during the afterglow of a condensed low-pressure helium discharge by means of a 10-channel spectrum analyzer having a channel width of 0.1 Å. The temporal resolution was I.6 μs (e-folding time). The filling pressure ranged from one to twenty Torr. The same relative peak structure was observed during the plasma build-up phase and the afterglow, only the intensities of the peaks were different in the two cases. Our measured profiles are quite similar to those obtained under different experimental conditions by other authors who explained the structure as being due to Baranger-Mozer plasma satellites. In contrast to this we did not find any correlation between electron density and peak position, i.e. the interpretation as Baranger- Mozer plasma satellites has to be excluded. The wavelengths of a number of peaks agree well with already identified He2 molecular lines, and there are sufficient experimental indications to conclude that the prominent part of the satellite structure originates from He0 molecular transitions most of which have not yet been identified.
Kinetic simulation of a low-pressure helium discharge with comparison to experimental measurements
