Measurements of Plasma Electron Temperature Utilizing Magnesium Lines Appeared in Laser Produced Aluminum Plasma in Air

Abstract

We have utilized the relative intensity of magnesium lines originated from the Mg I at 285.2 nm and Mg II at 280.27, 279.55 nm to measure the plasma electron temperature. The plasma was produced via interaction of Nd:YAG laser with solid aluminum target contains traces of magnesium. The magnesium lines were found to suffer from optical thickness which manifests itself on the form of scattered points around the Saha-Boltzmann line. We have utilized a simple method used for rapid calculation to the amount of absorption to these lines via comparison of the electron densities as deduced from magnesium lines to that evaluated from the optically thin hydrogen H α line at 656.27 nm appeared in the same spectra under the same condition. A correction to the magnesium spectral lines intensities was carried out; hence the corrected temperatures were re-evaluated. The measurements were repeated at different delay times ranging from 1 to 5 μsec. This work emphasizes on the importance of correcting the emitted spectral line intensity against the effect of self absorption before using them in the calculation of plasma electron temperature in laser induced breakdown spectroscopy (LIBS) experiments.

Stand-off laser-induced breakdown spectroscopy of aluminum and geochemical reference materials at pressure below 1 torr

“…is the line width in FWHM, w is the electron impact width parameter, N e is the plasma electron number density, and N r is the reference electron density [16][17][18]. The electron impact broadening width parameter w for the Al I 396.15 nm line is given by Griem with the reference electron density, N r = 10 18 cm -3 [19].…”

Experimental Determination of Electronic Density and Temperature in Water-Confined Plasmas Generated by Laser Shock Processing

“…In 2010, Parigger and Oks [20] presented a review about plasma diagnostics based on Stark broadening of hydrogen Balmer lines in laser-induced breakdown of plasma. Later, in 2012, the Hα-line was used again by El Sherbini et al [21] to determine the electron density in aluminum plasma and to correct the self-absorption in the Mg I and Mg II spectral lines present in this plasma. In 2004, De Giacomo et al [22] completed several experiments of laser induced breakdown spectroscopy in aqueous solution.…”

Influence of the homogeneous magnetic field of the laser-induced breakdown spectroscopy of copper plasma

“…The Stark broadening effect using to calculate the electron density requires a line which is free from self-absorption [12]:…”