Effect of ambient pressure on the generation and the propagation of plasmas produced by pulsed laser ablation of metal Al in air

Simultaneous time-and space-resolved emission spectra from a Nd: YAG laser-ablated plasma on an Al target have yielded quantitative information on the generation and the propagation of species in the plasma. Five ambient pressures from atmosphere to 5 Pa were chosen. The experimental results showed that the characteristics of the species in the plasma were strongly influenced by the ambient pressure. The mean spatially projected ranges of Al2+ ions in the atmosphere of different densities were calculated in theory, and the slowing-down processes were simulated by using a popular Monte Carlo simulation program, TRIM90. The calculated results can be used to explain observed experimental phenomena.