Spatial and Temporal Behavior of a Laser Generated Titanium Plasma

Optical emission studies have been performed on the laser ablation of Titanium metallic targets. The high intensity radiation of a pulsed N₂ laser (337.1 nm; 8 J/cm²) was focused onto the target to generate a short living (150 ns) plasma cloud that expands away from the surface into vacuum at high velocities. Time resolved measurements were taken as a function of the distance from the studied surface with a spatial rsolution of 20 µm, by collecting the emitted light in a direction perpendicular to the plasma expansion axis. A simple diffusion model with a source term is proposed to demonstrate the interaction of the laser beam with the plasma plume, as derived from analysis of the space-time behavior of several UV and visible atomic transitions.