Laser scattering by metallic particles in two-phase nozzle flow into a vacuum

For several years the Max-Planck-Institute for Extraterrestrial Physics has performed experiments with artificial barium clouds in space by means of research rockets and satellites in order to investigate electric fields and currents in the ionosphere and in the magnetosphere. The processes which lead to the formation of these artificial clouds were simulated in laboratory in order to optimize the barium vapor yield and to obtain a better insight into the initial phase of the clouds. In these experiments the combustion of excess barium with copper oxide, the two-phase flow of the combustion products through a nozzle and their expansion into a 20 m³ vacuum chamber were investigated in detail. Purpose of this work is to measure through detection techniques of scattered laser light and thermal radiation: 1) the density of small metall particles on the particle jet axis, 2) the particle velocity, 3) the thermal radiation of larger particles, and 4) the position of the Mach disk which limits the free nozzle jet downstream. This work was carried out at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany.