Abstract
The aim of this paper is to evaluate the effect of the laser beam energy on the properties of the plasma generated by focusing an intense laser beam on Zn solid targets in air at atmospheric pressure. Plasma is generated using Nd-YAG pulsed laser from Quanta at the fundamental and visible wavelength, its duration being 6 ns. This paper has been done at laser energies of 350, 200, and 100 mJ for the fundamental wavelength, and of 400, 200, and 100 mJ for the second-harmonic laser. The emitted light is collected by a fiber cable and illuminates the entrance slit of an Acton grating spectrometer equipped with intensified charge coupled device camera from photoionization at several delay time intervals. Boltzmann plots of Fe I spectral lines are used to obtain the excitation temperature evolution of the produced plasmas. The evolution of the plasma density is obtained from the Stark full-width at half-maximum of the Si I line at 288.16 nm and Al II line at 281.6 nm. In this paper, we are able to perform experiments at different laser energies and different delay times, which also allow us to study the dependence of the plasma evolution on the laser wavelength.