PNNL

Abstract

We report spatio-temporal evolution of emission and absorption signatures of Al species in a nanosecond (ns) laser-produced plasma. The plasmas were generated from an Inconel target, which contained~0.4 wt. % Al, using 1064 nm,˜6 ns full width half maximum pulses from an Nd:YAGlaser at an Ar cover gas pressure of˜34 Torr. The temporal distributions of the Al I (394.4nm) transition were collected from various spatial points within the plasma employing time-of-flightemission and laser absorption spectroscopy and they provide kinetics of the excited state and groundstate population of the selected transition. The emission and absorption signatures showed multiple peaks in their temporal profiles although they appeared at different spatial locations and timesafter the plasma onset. The absorption temporal profiles showed an early time signature which represents shock wave propagation into the ambient gas. We also used emission and absorption spectral features for measuring various physical properties of the plasma. The absorption spectral profiles are utilized for measuring linewidths, column density, and kinetic temperature while emission spectra were used to measure excitation temperature. A comparison between excitation and kinetic temperature was made at various spatial points in the plasma.