Spectroscopy diagnostics of a low temperature laser ablated LiAg plasma plume

Abstract

In experiments performed at Sandia National Laboratories, laser-generated LiAg plasma plumes were produced by irradiation of solid targets using a 10 ns pulse duration, 1×108 W/cm2 intensity Nd YAG laser. Time- and spatially resolved (along a direction normal to the target’s surface) optical spectra were recorded with a framing spectrograph. The observed spectra consist of optical line emission in Li and Ag atoms. Evidence of ions in the plume is suggested by the presence of a forbidden line and Stark-broadened line shapes. A spectroscopic model based on time-dependent collisional-radiative atomic kinetics that self-consistently calculate the Li and Ag level populations in conjunction with detailed line shapes and radiation transport is used to interpret the data. From this analysis, temperature, density, and ionization in the plume as a function of time and position along the normal to the target surface are extracted.