ИСТИНА

Optical emission spectroscopic methods are often used for plasma diagnostics by spectral lines broadening due to collisions of electrons and emitting particles and ions. Electron density calculation with the use of Stark broadening is a remote and non-contact technique even in non-equilibrium plasma. Not surprisingly, it is widely used to characterize the glow discharge, discharge in a hollow cathode, high-density star plasma and other plasma objects. However, we need the following parameters Stark shift and width for the determination of the electron density. They are reliably calculated for hydrogen-like atoms and ions. Parameters for lines of other species are hardly calculated by numerical methods. Experimental determination of the Stark parameters are seriously hampering by the following reasons: a heterogeneity of plasma sources, a hyperfine structure of the resonance lines sometimes comparable with the Doppler broadening, and self-absorption. There have been made several attempts for experimental determination of the Stark parameters of manganese resonance lines, but the data are strongly disagreed [1,2]. In this work we used a "long" spark for producing laser plasma to reduce the heterogeneity of a plasma and aluminum alloys with low manganese content as a target to suppress the self-absorption. A long spark had a relatively low temperature and electron density (T=5000 K, Ne=8,7×1016 cm-3 at delay 1.5 μs). Stark widths of Mn I resonance lines were estimated as a value about 9-10 pm at Ne=1017 cm-3. However, we have not observed evident Stark shifts of these lines.