Laser-induced plasma characterization using line profile analysis of chromium neutral atom and ion transitions

- Line profiles of Cr I-II transitions were analyzed for plasma characterization.
- A model of a homogeneous plasma was employed with a computational fitting algorithm.
- The plasma was characterized through its temperature, electron and atom/ion densities.
- The results were interpreted with a picture of two homogeneous plasma regions.

In this paper, line profile analysis of several Cr transitions was carried out for characterization of a laser-induced plasma. The plasma was generated on a metallic alloy (nominal Cr concentration 29.7%) in air at atmospheric pressure by using an infrared Nd:YAG laser. The emission intensities of 24 Cr I lines and 25 Cr II lines were measured spatially integrated along the line-of-sight with good resolution. Their line profiles were analyzed applying a computational fitting algorithm under a framework of a homogeneous plasma in thermodynamic equilibrium. The effects of self-absorption and spatial inhomogeneity were taken into account. The plasma temperature and the parameters Nl (the atom/ion concentration times the length of the plasma along the line-of-sight) were accurately determined, and the electron density was estimated. The results were properly interpreted under the employed approach, demonstrating the important influence of the issues investigated on characterizing the physical state of laser-induced plasmas.