Noble gas line profiles in dense plasmas. I. Argon

Stark widths and shifts of the Ar I 696.5 nm and of the Ar II 480.6, 484.7 and 434.8 nm lines have been measured in the range of electron density and temperature 0.6-1.5*10 18 cm -3 , 16200-18700 K. These high-density plasmas are created in linear flash-tubes. The plasma parameters are principally determined by measurements of the continuum radiation, from the intensity of optically thick lines in their centre and by the condition of local thermodynamic equilibrium of the plasma. The electron density and temperature radial profiles so deduced are found to be practically flat over more than half of the tube radius. In this quasi-stationary stage of the plasma, the experimental line profiles are recorded by an optical multichannel analyser coupled with a high-dispersion spectrometer. The profiles are analysed and fitted to a Lorentzian function. The Stark parameters, width and shift, show a non-linear dependence against the electron density.