Determination of excitation temperature in laser-induced plasmas using columnar density Saha-Boltzmann plot.

• 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. 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 Saha-Boltzmann 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. [ABSTRACT FROM AUTHOR]