Spectroscopic Diagnostics of Laser-Induced SilverPlasma Using LIBS at Different Laser Energies

Abstract

Laser-induced breakdown spectroscopy (LIBS) has been used to investigate the plasma
generated from a silver target by the Nd:YAG laser system at a wavelength of 1064 nm. The plasma was
produced at different laser pulse energies (500, 600, 700, and 800 mJ) to study the effect of laser energy
on plasma parameters. The electron temperature (Te) was determined using the Boltzmann plot method,
while the electron density (ne) was calculated using Stark broadening of the spectral lines. Moreover,
other plasma parameters such as plasma frequency (fp), Debye length (λD), and Debye number (ND) have
been evaluated. The results showed that the electron density increased from 3.11×10¹⁷ cm⁻³ to 5.32×10¹⁷
cm⁻³ with increasing laser energy, while the electron temperature increased from 0.64 eV at 500 mJ to
0.84 eV at 800 mJ. The plasma frequency also increased from 5.01×10¹² Hz to 6.55×10¹² Hz, whereas
the Debye length decreased from 3.37×10⁻⁷ cm to 3.06×10⁻⁷ cm. The Debye number (ND) was greater
than unity, confirming that the generated plasma satisfies the basic conditions of a stable ionized plasma.
These results indicate that increasing laser energy significantly influences excitation, ionization
processes, and overall plasma characteristics.