Spatial distribution of hydrogen and other emitters in aluminum laser-induced plasma in air and consequences on spatially integrated Laser-Induced Breakdown Spectroscopy measurements

Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

“…Several authors observe a different behavior of the n e axial variation during the ablation of aluminum in air. 23,32 Their axial distribution of n e was spatially structured, showing a shallow minimum. This is attributed to the recombination processes occurring in regions of high number density.…”

“…However, when the thermal conductivity is low, argon, the spatial variation of the temperature is quasi-linear with independence on the gas pressure. De Giacomo et al, 23 Barthélemy et al 32 and Ma et al 36 have studied the ablation of aluminum in air. They observed that the temperature has a special behavior: it drops close to the target side and at the plasma edge and this is attributed mainly to the thermal conduction from the plasma toward the solid target and to radiative cooling, respectively.…”

“…The densities and temperatures show similar spatial distributions for plasmas generated in air and argon with a maximum in the central region. De Giacomo et al 23 have studied the expansion and spatial structure of an aluminum plasma produced by a Nd:YAG laser in air at atmospheric pressure. They find that the spatial distribution of n e presents a shallow minimum that progressively shifts towards greater distance from the target surface when time increases.…”

Calibration-Free Laser-Induced Breakdown Spectroscopy: State of the art

“…Characterization of plasma features have been reported in the literature [69][70][71][72][73][74][75][76][77][78][79]. Several researchers proposed models to take into account the plasma inhomogeneity and its consequences on the spectral line intensity [57,80,81].…”

Orthogonal Double-pulse versus Single-pulse laser ablation at different air pressures: A comparison of the mass removal mechanisms

“…The hydrogen emission, which is clearly observed in all the spectra, is probably due to the water vapor coming from the natural humidity of the air, and is in part adsorbed on the target surface. In a recent paper [31], where spatial resolved measurements are presented, it was shown that the H I line emission mainly comes from the inner part of the plume, as well as the emission from species ablated from the target. This observation supports the validity of such method for calculating the electron density in the plasma.…”