Influence of laser energy on the electron temperature of a laser-induced Mg plasma

Abstract

radiations in this process are used for the identification of the elemental composition of the sample [7][8][9].LIBS offers many advantages over other spectroscopic techniques such as mass spectroscopy, electrode spark and inductively coupled plasma. Some of LIBS unique advantages include the ability to make in situ analysis even in hostile environment, remote sensing, little or no preparation of the sample, and multi-element analysis [10][11][12]. Based on these advantages, LIBS has been extensively investigated on several samples including liquids [13], gases [14] and as well from non-conducting and conducting solids [15].LIBS is also a spectroscopic technique for the determination of the density of electron, electron temperature and number densities of the plasma plume [16,17]. Laserinduced plasma temperatures are influenced by various experimental conditions such as ambient surrounding, laser energy and laser pulse width. Most of the studies on LIBS temperatures report that the plasma temperature tends to increase with increasing laser energy, pulse width, laser wavelength and ambient pressure [18][19][20][21].Although LIBS has been employed successfully in several experimental and theoretical works, to analyze the spectroscopic composition of the samples, there are still many aspects which need to be investigated [6]. For example, Barthelemy et al. [22] investigated the influence of the laser parameters of an aluminum-induced plasma. They reported that the temperature slightly decreases at the plasma edge and close to the aluminum surface. This decrease in temperature at the plasma edge is basically caused by radiative cooling, while the decrease in temperature at the aluminum surface is as a result of thermal conduction. The authors also found that at the first microsecond of the ablation plume, the electron density was spatially homogeneous.Zhang et al.[23] also reported on the influence of laser parameters on plasma temperature. Their results predicted Abstract The magnesium plasma induced by a 1064-nm Q-switched Nd:YAG laser in atmospheric air was investigated. The evolution of the plasma was studied by acquiring spectral images at different laser energies and delay times. We observed that the intensities of the spectral lines decrease with larger delay times. The electron temperature was determined using the Boltzmann plot method. At a delay time of 100 ns and laser energy of 350 mJ, the electron temperature attained their highest value at 10164 K and then decreases slowly up to 8833.6 K at 500 ns. We found that the electron temperature of the magnesium plasma increases rapidly with increasing laser energy.

Spatiotemporal spectroscopic characterization of plasmas induced by non-orthogonal laser ablation

“…Similar temperatures (in the order of 1E+4 K) have been commonly reported for orthogonal ablation with pulse energies ranging from 20 mJ to 200 mJ [34][35][36][37][38] , which validates our results. Overall, the observed temporal evolution of the temperature is in good agreement with existing reports [39][40][41][42][43] . In addition, for each plasma, the ionization fraction calculated according to (1,2) approached unity, which is in line with studies of orthogonal ablation 44 .…”

Investigation into the Effect of Increasing Target Temperature and the Size of Cavity Confinements on Laser-Induced Plasmas

“…The electron temperature was estimated from the Boltzmann and Saha-Boltzmann plot methods by utilizing the relative intensities of the emission lines of the Mg and Ti plasmas, respectively. The plasma obtained was optically thin, and the condition for local thermodynamic equilibrium to exist was warranted [44,45].…”

“…The expression in Equation (2) can be condensed into the form of the Boltzmann's equation in Equation (1). Where E IP is the ionization energy, m is the mass of the electron, and the subscripts 1 and 2 denotes the neutral and ionic lines, respectively [44,[47][48][49][50].…”

Laser Spectroscopic Characterization for the Rapid Detection of Nutrients along with CN Molecular Emission Band in Plant-Biochar

“…In the LIBS technique, the plasma emission spectra of the target sample are investigated. The plasma generated at the surface of the target, such as gas, liquid, and solid, is normally generated when the high-power laser beam is focused onto the target material [ 7 , 8 , 9 ]. The plasma emission spectrum from the laser-produced plasma gives the optical fingerprints of the sample ingredients [ 10 , 11 ].…”