Condensed Zinc Particle Size Determined by a Time Discrete Sampling Apparatus

This paper describes an experiment in which a novel sampling technique is employed to determine the size distribution of zinc particles originating through homogeneous condensation of zinc vapor expanding with a helium carrier gas through a supersonic nozzle. Decelerating a skimmed portion of the nozzle flow by mixing with quiescent air at matched pressure was found to be an effective method of sampling. The particles were collected on a cylinder shuttered in a way which permitted several time discrete samplings within a very short time span. Electron microscope analysis of the particles sampled showed a narrow distribution of sizes with 80% of the particles having diameters within a 100 A range and a peak number of particles having diameters about 135 A.