Effects of density distribution on the Stark width and shift of spectral lines in plasma

A plasma density distribution that arises due to a finite observation volume or is inherent due to turbulence, needs to be accounted for when using spectral lines for plasma diagnostics. Such a distribution distorts line shapes in a non-trivial way and alters their intensities. In the present study, these effects are analyzed. The results are presented analytically and also tabulated for two types of the density distribution, Gaussian and log-normal, over a wide range of the distribution variance. The results are applicable to practically any type of spectral lines used for plasma density diagnostics. Provided also are considerations for choosing spectral lines to minimize uncertainties if a density distribution is expected but its extent is unknown. In addition, an approach for inferring the density distribution based on the line-shape asymmetry is suggested.