Delving into the time dependent properties of thorium laser induced plasma by optical emission spectroscopy

Abstract

AbstractLaser-induced breakdown spectroscopy (LIBS) presents a promising avenue for both qualitative and quantitative analysis. This technique utilizes emission spectral study from laser-induced plasma (LIP) generated due to ablation of samples from surfaces. From the point of view of understanding plasma physics, this study delves into the parametric analysis of Laser-induced plasma of Thorium, which is a key element in India’s pioneering three stage power program. Following optimization of experimental parameters like acquisition delay and number of laser shots, key plasma parameters such as Temperature and Electron density of the plasma were computed. For description of LIP, ‘Local Thermodynamic Equilibrium’ (LTE) model is widely used. The model’s validity was meticulously scrutinized in entire temporal region of analysis. Furthermore, investigations into the impact of laser parameters like irradiance, revealed changes in magnitude of plasma parameters along with their evolution pattern and it was concluded that the temporal holding region of LTE strongly depends upon the laser parameters. Next, temporal evolution study of the peak broadening within the plasma revealed the importance of optimization of the experimental parameters, and differences between the decay trends of ionic and atomic lines were clarified. In addition, experiments were carried out exploring the influence of different ambient atmospheres (Air, He, and Ar) on spectral intensity and plasma lifetime, both of which were found to have the order Ar > Air > He. This provided crucial insights into the plasma-atmosphere interaction, which was also manifested by the different rates of decay trend of plasma parameters. In summary, this complete study offers a valuable tool for diagnosing the plasma properties of complex sample matrices like Thorium, thereby advancing our understanding of LIBS applications a step forward.