TITLE:
Measurements of Plasma Electron Temperature Utilizing Magnesium Lines Appeared in Laser Produced Aluminum Plasma in Air
AUTHORS:
Ashraf M. El Sherbini, Abdel Aziz S. Al Aamer, Ahmed T. Hassan, Tharwat M. El Sherbini
KEYWORDS:
LIBS; Self Absorption; Mg-Lines; Plasma Parameters
JOURNAL NAME:
Optics and Photonics Journal,
Vol.2 No.4,
December
28,
2012
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 Hα 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.