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

Abstract

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