Optical emission studies of the mercury plasma generated by the fundamental, second and third harmonics of a Nd : YAG laser

Abstract

We report the first measurements of the optical emission spectra of mercury plasma produced by the fundamental, second and third harmonics of a Nd : YAG laser, which reveals numerous transitions due to the neutral and singly ionized mercury. The excitation temperature has been determined from the Boltzmann plots, whereas the electron number density is estimated from the Stark broaden profile of the spectral lines. The estimated range of the excitation temperature and the electron number density is (7000–14000) K and (3.6 × 1016 to 2.5 × 1017) cm−3, respectively. The behaviour of the excitation temperature and the electron number density with the laser irradiance has been studied. The spatial distribution of the temperature and the electron number density has also been investigated besides the studies of absorption in the plasma through inverse bremstrahlung and photoionization.