Measurement of extinction coefficients of laser-produced aluminum plumes

Abstract

Radial spectral intensities (0.632 yum) were measured using a He:Ne probe laser scanning an aluminum plume formed by Ndiglass laser irradiation of a target surface. Furthermore, techniques were developed to measure the radial distributions of the extinction coefficients in an axisymmetric, laser-produced aluminum plume. The techniques developed allow for measurements of these distributions as functions of time, wavelength, and elevation above the aluminum target. The extinction coefficients determine the ability of the plasma to attenuate incident laser radiation. The extinction coefficient distribution was determined by scanning a He:Ne probe laser through the plume and converting line-of-sight measurements to a radial distribution. Results indicate that the aluminum plume is optically thin in the first 80 /*s after formation and that the radial extinction coefficient profile has a Gaussian distribution.