Determination of excitation temperature in laser-induced plasmas using columnar density Saha-Boltzmann plot
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Determination of excitation temperature in laser-induced plasmas using columnar density Saha-Boltzmann plot. In exploiting the analytical capabilities of plasma-based spectroscopy method, the evaluation of plasma parameters, particularly the plasma temperature, is a crucial step. In this work, a modified SahaBoltzmann plot, which uses the columnar densities of atomic and ionic ground levels, is utilized to calculate the plasma temperature in a laser-induced plasma from an aluminum alloy target. The columnar densities are here calculated by quantifying the self-absorption of resonance lines. It is demonstrated that this is a promising method for accurate determination of plasma temperature. To validate the capability of this technique, plasma emission is measured at different gate delay times. For each delay, excitation temperature is calculated both by the conventional Saha-Boltzmann plot (by using the excited states) and by exploiting the new Columnar Density Saha–Boltzmann (CD-SB) plot. The results suggest that at later times of the plasma evolution, the CD-SB plot can be more suitable for the determination of plasma temperature than conventional Saha-Boltzmann plot. These findings provide a new approach for physical characterization of plasmas and give access to a wealth of information about the state of plasma.
Determination of excitation temperature in laser-induced plasmas using
columnar density Saha-Boltzmann plot
Ali Safia, S. Hassan Tavassolia,⇑, Gabriele Cristoforettib, Stefano Legnaiolic, Vincenzo Palleschic,
Fatemeh Rezaeid, Elisabetta Tognonib
a Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran, Iran
b National Institute of Optics of the National Research Council (INO-CNR), Via G. Moruzzi 1, Pisa, Italy
c Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Via G. Moruzzi, 1, Pisa, Italy
d Department of Physics, K. N. Toosi University of Technology, 15875-4416 Tehran, Iran
h i g h l i g h t s
g r a p h i c a l
a b s t r a c t
Characterization of LIP by the
Columnar Density Saha-Boltzmann
(CD-SB) plot.
Use of strongly self-absorbed lines to
calculate the plasma temperature.
Temporal evolution of the plasma
temperature by CD-SB plot.
CD-SB plot as a promising method to
obtain plasma temperature at later
times.
CD-SB plot does not require the
calibration of the detection system.
a r t i c l e
i n f o
a b s t r a c t
Article history:
In exploiting the analytical capabilities of plasma-based spectroscopy method, the evaluation of plasma
Received 7 October 2018
Revised 17 January 2019
Accepted 18 January 2019
Available online 26 January 2019
parameters, particularly the plasma temperature, is a crucial step. In this work, a modified Saha-
Boltzmann plot, which uses the columnar densities of atomic and ionic ground levels, is utilized to cal-
culate the plasma temperature in a laser-induced plasma from an aluminum alloy target. The columnar
densities are here calculated by quantifying the self-absorption of resonance lines. It is demonstrated that
Keywords:
Plasma
Spectroscopy
LIBS
Excitation temperature
this is a promising method for accurate determination of plasma temperature. To validate the capability
of this technique, plasma emission is measured at different gate delay times. For each delay, excitation
temperature is calculated both by the conventional Saha-Boltzmann plot (by using the excited states)
and by exploiting the new Columnar Density Saha–Boltzmann (CD-SB) plot. The results suggest that at
later times of the plasma evolution, the CD-SB plot can be more suitable for the determination of plasma
Self-absorption
temperature than conventional Saha-Boltzmann plot. These findings provide a new approach for physical
Saha-Boltzmann plot
characterization of plasmas and give access to a wealth of information about the state of plasma.
2019 The Authors. Published by Elsevier B.V. on behalf of Cairo University. This is an open access article