Speaker
Dr
Hanif Muhammad
(National University of Sciences & Technology, Islamabad, Pakistan)
Description
Spectroscopic studies of silicon (Si) plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of an Nd: YAG laser by placing the target material in open air at atmospheric pressure are presented.. The electron temperature measurements have been estimated using the Boltzmann plot method. The electron temperature as a function of laser irradiance (2 x $10^{10}$ to 6.5 x $10^{10}$ W/cm$^2$) ranges from 11290 to 14120 K (for fundamental), and 11660 to 13750 K (for second) laser respectively. The electron number density is calculated using Stark broadening profile of 288.15 nm (3p4s 1P1 → 3s23p2 1D2)transition. The electron number density as a function of laser irradiance ranges from 2.20 x $10^{16}$ to 1.55 x $10^{17}$/cm$^3$ (for fundamental) and 1.09 x $10^{16}$ to 1.80 x $10^{17}$/cm$^3$ (for second) laser respectively. The spatial distribution of electron temperature and electron number density shows same decreasing trend up to 2.0 mm from the target surface (0.05 mm). It is observed that electron temperature and number density increases as laser irradiance is increased. In addition inverse bremsstrahlung absorption coefficient has been estimated. Apart from that variation of these plasma parameters (electron temperature and number density) along-with variation of distances in the direction of propagation of plasma plume have also been investigated. The plasma parameters calculated based on this research work are within the range already reported in the literature.
Primary author
Dr
Hanif Muhammad
(National University of Sciences & Technology, Islamabad, Pakistan)
