Study of laser produced plasma plume and its dynamics in nickel thin film

Abstract

Abstract newlinePlasma plume formation from a nickel thin film in rear ablation geometry, its propagation and interaction newlinewith ambient gas using lasers of different pulse widths and wavelengths has been studied newlinein a range of background pressures. The plasma plume dynamics is studied using fast imaging, newlineLangmuir probe and spectroscopic diagnostics. Stark broadening of neutral nickel lines is studied newlinein correlation with Hand#8629; line broadening and the Stark broadening parameters of nickel lines are newlineestimated. The Stark parameters estimated for nickel lines are used for the estimation of plasma newlinedensity at different background pressures. In the rear ablation geometry, the evolution of plasma newlineplume, directionality, splitting and expansion are found to depend on parameters like laser pulse newlinewidth, wavelength,fluence, film thickness and background pressure with which the plume interacts. newlineThe experimental results show that the background pressure confines the plasma plume and newlinethus helps increase in the electron density. In the case of fs ablation, the plume shows a linear newlineexpansion at lower background pressures, while at higher pressures the expansion appears to follow newlineshock wave like nature. For ps ablation the expansion appears to follow a blast wave model newlineat lower pressures, which, however, fits with drag model at higher pressures. In case of ns ablation, newlineshock wave like nature is observed for all the pressures. The dependence of wavelength newlineand laser fluence on plume formation is also investigated. It is observed that the dynamics of newlineconstituent species in plasma plume say, neutrals and ions exhibit distinct behavior which can be newlineseen from the spectroscopic and fast imaging. The TOF spectra for the neutral and ionic species of newlinethe plasma plume show that it has multiple distributions probably, exhibiting a signature of their newlineorigin. The numerical fit of Shifted Maxwell Boltzman distribution provides some information newlineinto the generation mechanism or the energy gain of different constituents of the plasma. The different newlinediagnostics u