DYNAMIC SCREENING EFFECTS ON THE SHIFT AND THE SHAPE OF SPECTRAL-LINES

A many particle theory has been applied to investigate collective effects on the shift and the shape of spectral lines. It is shown that the line shift becomes nonlinear with respect to the electron density if the energy distance of the radiators levels is in the order of magnitude of the electron plasma frequency. For weakly non thermal plasmas dips on the line profile occur near the electron plasma frequency.