Spectroscopy Measurements of Laser-Induced Molybdenum Plasma

Abstract

Molybdenum plasma in air at atmospheric pressure was carried out by utilizing Nd-YAG laser at fundamental wavelength 1064 nm, 0.206 mJ input energy, 5 ns pulse duration and repetition rate 10 Hz. After plasma formation, the optical fiber was used to collect plasma emission. The spectral analysis was displayed in the Local Thermal Equilibrium (LTE) state. Electron temperature was estimated by Boltzmann plot method and electron density was calculated from Stark broadening and compared with electron density of Hα-line at 656.3 nm which has reliable values. The temperature of plasma and density were evaluated for different positions along the expansion axis. The influence of the input power on plasma was studied. The electron density varied from 5 ×1018 to 3.5×1019 cm-3. These parameters are important in environmental and industrial application. At distance of 10 mm from the target, the electron temperature has a minimum value while the electron density shows a maximum value.