Condensation In A Rapidly Expanding Metal Vapor Inert Gas Mixture

An investigation of the condensation of metal vapor in an inert carrier gas accelerated through nozzles was carried out. The mixture used is primarily zinc vapor in helium gas. Two types of condensation measurements are made. Measurement of particle size is made in the tunnel. Determination of condensation onset point is made in the exploding-wire system. Particle size is determined by means of a shuttered sampling device developed for the purpose combined with electron microscope techniques evolved. The condensation onset point is determined by nozzle static pressure measurement. Simplified computational analyses are made to predict conditions for the measured condensation onset point. They are also used as a guide for the more complex two component non-equilibrium expansion computation which may predict the location of the onset point as well as particle size. Measurements of particle size at the exit of a nominal Mach 25 (helium) nozzle showed a major portion of the total particles to be less than approx. 70 A in diameter. The pressure measurements made in a nominal Mach 3 nozzle indicated a large degree of supercooling. (Author).