Time-resolved PLIF imaging of Cu in a laser-ablated copper plasma plume

Planar laser-induced fluorescence (PLIF) has been used to determine the relative number density of ground state copper atoms in laser-ablated plasma plumes. An ablation laser power flux of ~1.5 GW/cm ² is applied to a solid copper target in a background gas, producing a plasma plume suitable for studying homogeneous copper vapor condensation. Density is measured at postablation time delays ranging from 5 μs to 10 ms with 1-100 torr of either argon or helium as the background gas. Planar laser-induced fluorescence images are used to spatially resolve the relative density within the plume, The decrease in density is due to the homogeneous condensation of copper vapor to form particulate