Measurement of the Electron Temperature in a Metallic Copper Using Ultrafast Laser-Induced Breakdown Spectroscopy
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Journal of Russian Laser Research, Volume 41, Number 5, September, 2020
MEASUREMENT OF THE ELECTRON TEMPERATURE IN A METALLIC COPPER USING ULTRAFAST LASER-INDUCED BREAKDOWN SPECTROSCOPY Mohamed Fikry,1,2 Walid Tawfik,3∗ and Magdy Omar1 1 Department
Physics, Faculty of Science Cairo University, Cairo, Egypt
2 Egypt
Nanotechnology Center (EGNC) Cairo University, Cairo, Egypt
3 National
Institute of Laser Enhanced Sciences (NILES) Cairo University, Cairo, Egypt
∗ Corresponding
author e-mail:
walid tawfik @ niles.edu.eg
Abstract In this paper, we provide the laser-induced breakdown spectroscopic (LIBS) analysis of copper under the action of the ultrafast picosecond Nd:YAG laser and the specifications calculated from the electron temperature of plasma generated by the fundamental (1064 nm), second (532 nm), third (355 nm), and fourth (266 nm) laser harmonics. In this work, a laser pulse energy of 60 mJ ±5% with a duration of 170 ps, a beam diameter of ∼0.5±0.1 mm, and a laser intensity 1.79·1011 W/cm2 ±8% for a single shot was applied. The electron temperature is measured using three spectral lines of neutral copper (Cu I) at 515.3, 521.8, and 522.0 nm, according to the Boltzmann plot model where the local thermodynamic equilibrium (LTE) conditions were assumed. The electron temperature values observed are 13422, 15152, 16605, and 17783 K for laser wavelengths of 266, 355, 532, and 1064 nm, respectively. The experimental analysis reveals that the plasma electron temperature rises with the laser wavelength. Variations in the mass ablation rate, inverse Bremsstrahlung absorption, and photoionization with the laser wavelength variation allow us to explore the interaction dynamics. The results obtained allow for variation of the generated plasma electron temperature by guiding the picosecond pulse wavelengths; the later may allow for controlling plasma interactions, which can be applied in plasma spectroscopy of material science.
Keywords: ultrafast picosecond laser pulse, laser-induced breakdown spectroscopy (LIBS), copper plasma, electron temperature, Boltzmann plot, local thermodynamic equilibrium (LTE).
1.
Introduction
A material breakdown can be generated by the plasma interaction, which created significant change in a matter temperature to overcome the binding electrostatic forces between its electrons and nuclei [1]. Subsequently, very hot gas is therefore collected of a mixture of neutral atoms, electrons, and ions [2]. Plasma breakdown spectroscopy is an important diagnostic method in plasma physics and technology. The plasma has two main categories, according to its temperature – the hot plasma with temperature Tp ranged from 106 K to 108 K and the cold plasma with temperature ranged from 103 K to 104 K [3]. Manuscript submitted by the authors in English on July 3, 2020. c 2020 Springer Science+Business Media, LLC 1071-2836/20/4105-0484 484
Volume 41, Number 5, September, 2020
Journal of Russian Laser Research
Using a laser beam to induce material breakdown by focusing a high-energy laser pulse on a
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