Two-Dimensional Spatial Distribution of the Time-Integrated Emission from Laser-Produced Plasmas in Air at Atmospheric Pressure

Abstract

Emission from Nd:YAG laser-produced plasmas generated in air at atmospheric pressure has been studied with spatial resolution. With the use of a charge-coupled device (CCD), two-dimensional spatial distributions of the time-integrated line emission from plasmas of metallic (copper and stainless steel) and ceramic (alumina) samples were measured for laser power densities in the range 80–900 GW/cm2. Geometrical parameters (distance of the maximum, width in two directions) and the total space- and time-integrated emission were obtained as a function of power density. At the range 100–700 GW/cm2, the formation of a plasma in air for the metallic samples was shown to be responsible for a decrease in the total intensity of lines emitted from the sample plasma, accompanied by effects in the spatial profiles along the laser direction. Beyond 700 GW/cm2, a sharp increase of the line intensities was observed, related to the absence of the shielding air plasma.