LASER PLASMA INTERACTION DURING VISIBLE AND IR LASER ABLATION OF CHROMITE MINERAL TARGET

摘要

In this work, we present optical emission studies of the laser induced Chromite mineral plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched pulsed Nd: YAG laser. The spectra predominantly reveal the spectral lines of neutral Cr as well as dominant spectral lines of constituent elements. The experimentally observed line profiles of neutral chromium have been used to extract the electron temperature (T_e) using Boltzmann plot method. Whereas, the electron number density (N_e) has been determined from the Stark broadened line profiles. We have also studied the variation of electron temperature and electron number density as a function of laser irradiance at atmospheric pressure. We have also studied the variation of these plasma parameters (T_e and N_e) as a function of the laser irradiance as well as distance along the direction of plasma plume. The validity of the assumption of local thermodynamic equilibrium (LTE) is also discussed in the light of the experimental data and analysis.