Experimental and theoretical studies of Stark profiles of Ar I 696.5 nm spectral line in laser-induced plasma

Abstract

We report the results of the Stark profile studies of the 696.543 nm Ar I spectral line in laser-induced plasma generated by a nanosecond Nd:YAG laser radiation at 532 nm in argon at reduced pressure. Plasma diagnostics was performed with the use of the laser Thomson scattering method, free from assumptions about the plasma thermodynamic equilibrium, its composition but also independently of plasma emission spectra. The profiles were investigated in wide range of electron densities and temperatures, from 2.81 · 1022 m−3 to 5.69 · 1023 m−3 and from 10 430 K to 73 400 K, respectively. Stark profiles were calculated using a semi-classical method as well as by N-body numerical simulations assuming a plasma in local thermodynamic equilibrium. Our studies show agreement within 20% between experimental Stark widths and those calculated by the semi-classical method while much bigger discrepancies were found with computer simulated ones. Importantly, Stark profiles of the investigated spectral line, both experimentally determined and computed, are highly sensitive to electron temperature.