Stark broadening measurements of Al II, Al III and He I 388.86 nm spectral lines at high electron densities

Abstract

Experimental Stark width broadening parameters (w) for 5 spectral lines of singly (Al II) and 8 spectral lines of doubly ionized aluminum atoms (Al III) are presented. The for Al III values are the first experimental data. The experiment was conducted in laser-induced plasma in helium‑hydrogen gas mixture at reduced pressure. The laterally resolved spectra are recorded side-on. The plasma parameters are inferred after applying inverse Abel transform. The electron densities ranging from (0.98–4.86)×1023 m−3 are estimated relying on broadening of hydrogen Hβ spectral line. The electron temperature in experiment was in the range 20 000 K to 28 000 K and it was determined applying Boltzmann and Saha-Boltzmann method. Stark broadening parameters for Al II and Al III spectral lines are compared with available experimental and theoretical results. We also present experimental Stark widths and shifts (d) for neutral helium 388.86 nm spectral line at electron densities above 1×1023 m−3, where the existing number of w and d data is limited. Some of new Al III w values are convenient for plasma diagnostics.