Stark broadening of lines from transition between states n = 3 to n = 2 in neutral helium

An experimental and computer-simulation study ^⋆

¹ Departamento de Óptica, Universidad de Valladolid, 47071 Valladolid, Spain
e-mail: gigosos@coyanza.opt.cie.uva.es
² University of Novi Sad, Faculty of Sciences, Department of Physics, Trg Dositeja Obradovića 4, 21000 Novi Sad, Serbia
e-mail: djurovic@uns.ac.rs

Received: 17 October 2013
Accepted: 3 December 2013

Abstract

Context. The Stark broadening of the spectral lines of the wavelengths 501.6, 667.8, 728.1, 388.9, 587.6, and 706.5 nm from neutral helium in plasmas are studied theoretically and experimentally.

Aims. The aim of this work is to provide information about the connection between the shape and width of spectral lines and the electron density and temperature to be used as a diagnostic tool.

Methods. The theoretical calculations were carried out through molecular dynamics computer simulations with noninteracting particles. The experimental measurements were done in a plasma of pure helium generated in an electromagnetically driven T-tube. The plasma diagnostics used previous results about the Stark broadening of the He I 447.1 nm and He I 492.2 nm lines and the coherence between the shape of these spectra and those obtained here. The electron temperature was obtained through a Boltzmann-plot of eight lines of Si II.

Results. Several tables of width and shift are provided in a wide range of electron density and temperature. Furthermore, we supply several fitting formulas, which allow calculating the plasma electron density from the measured values of the spectral line widths. The results obtained in the laboratory and in the simulations are compared with the data from the literature.