Emission Studies of Silicon Plasma Produced by a Nd: YAG Laser

Abstract

In the present experimental work emission studies of silicon (Si) plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Nd: YAG laser are studied. The electron temperature measurements have been estimated using the Boltzmann plot method. The electron temperature as a function of laser irradiance (2 × 1010 to 6.5 × 1010 W/cm2) ranges from 11290 to 14120 K (for fundamental), and 11660 to 13750 K (for second) laser respectively. The electron number density is calculated using the Stark broadening profile of 288.15 nm (3p4s 1P1 → 3s 23p 2 1D2) transition. The electron number density as a function of laser irradiance ranges from 2.20 × 10 16 to 1.55 × 1017/cm3(for fundamental) and 1.09 × 1016 to 1.80 × 1017/cm3(for second) laser respectively. The spatial distribution of electron temperature and electron number density shows the same decreasing trend up to 2.0 mm from the target surface (0.05 mm). It is observed that electron temperature and number density increase as laser irradiance is increased. In addition the inverse bremsstrahlung absorption coefficient has been estimated. Variation of these plasma parameters (electron temperature and number density) along with variation of distances in the direction of propagation of the plasma plume have also been investigated.