Measurement of submicrometer Al2O3 particles in plumes

Abstract

We made multiple-wavelength light transmission measurements at the edge of a plume from a small solid-propellant motor in order to determine the mean particle size and the in situ particle index of refraction. We retrieved the particle size distribution from the Sauter mean diameter and the geometrical standard deviation assuming a lognormal distribution. The good correlation of the data indicated the applicability of the technique with a relatively high confidence level and that submicrometer particles were dominantly present at the edge of the plume.