Astrophysical plasma diagnostics through analysis of Ar I line shape characteristics

Abstract

On the basis of five accurately recorded neutral argon (Ar I) line shapes (in the 4s-5p transition) we have recovered the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of three different plasmas created in a linear, low-pressure, pulsed arc discharge. The mentioned plasma parameters have also been measured using independent experimental diagnostic techniques. An excellent agreement has been found among the two sets of obtained parameters. This recommends our deconvolution procedure for plasma diagnostic purposes, especially in astrophysics where direct measurements of the main plasma parameters (T and N) are not possible. On the basis of the observed asymmetry of the Stark broadened line profile we have obtained not only its ion broadening parameter (A) which is caused by the influence of the ion microfield on the line broadening mechanism but also the influence of the ion-dynamical effect (D) on the line shape. The separate electron (We) and ion (Wi) contributions to the total Stark width, which have not been measured so far, have also been obtained and represent the first experimental data in this field. We have found a stronger influence of the ion contribution to the Ar I line profiles than the existing theoretical approximation provides. This is of importance for astrophysical plasma modeling and diagnostics.