Behaviour of the First Balmer Lines in a High Density Plasma

Observation of Balmer line profiles revealed their relative constriction and growing asymmetry with increasing ion density, measured in the range of 2 × 10 16 to 3 × 10 17 ion/cm 3 . The fit of these profiles with the existing theoretical profiles gives smaller densities by the use of higher series members and smaller densities by the use of a red wing as compared with that of a violet wing. The phenomenon is believed to be caused by a combined action of the transition from the impact to the quasi-static line broadening effect of electrons and of the dissolution (pre-ionization) of discrete energy levels. The change in the line broadening mechanism due to the electrons makes the line narrower than in the case in which there would be no such change, because the quasi-static broadening does not rise so steeply with density as the impact broadening. The dissolution effect on the other hand, is accompanied by a decrease in line intensity and in asymmetry, the red wing being narrower than the violet one. The dissolution estimated by the use of the available data is in accordance with the experimental evaluation.