Combined Spatial, Temporal, and Spectral Analysis of Absorption and Emission in a Laser-Produced Plasma

Spatio-temporal analysis of emission and absorption signatures of Al species in a nanosecond (ns) laser produced plasma (LPP) is presented. Plasmas were generated from an Inconel target containing Al by using 1064 nm, 6 ns full width half maximum pulses from an Nd:YAG laser at an Ar cover gas pressure of 34 Torr. Time-resolved emission and absorption (time-of-flight) from the Al I (394.4 nm) transition was collected from various spatial points within the plasma to study kinetics of the excited and ground state populations. Emission and absorption signatures showed multiple features in the temporal profiles appearing at different spatial locations and times after the plasma onset, including excitation of the Ar ambient gas, shock wave propagation, and plume expansion dynamics. Analysis of time- and space-resolved emission and absorption spectra were used to determine spectral linewidths, atomic number density, kinetic temperature, and excitation temperature. The results highlight that using time-of-flight measurements for high time- and space-resolution, combined with spectrally-resolved measurements to determine excitation temperatures and linewidths, provides a more complete picture of LPP spatiotemporal dynamics than is possible using each technique alone.