Grain Formation Experiments by a Plasma Jet Apparatus

Abstract

The observational fact that the interstellar and circumstellar dust grains are not crystalline but amorphous has been accumulated and it leads to the idea that the grain formation in space is a non-equilibrium phenomenon. In order to investigate the non-equilibrium condensation, we have developed a plasma jet apparatus. The high power of the apparatus enables to dissociate molecular sample gas completely and to obtain condensates from atomized gas. The purpose of our experiments is to examine the condensates from rapidly cooled atomized gas with various abundance ratios. In the experiments, we first focused on the condensation from mixtures of H, C, O, and Si atoms. Three kinds of gas mixtures, a mixture af H and C atoms, that of H, C, and Si atoms, and that of H, C, O, and Si atoms, were chosen as reactant condensable gases. Our experiments were executed with entirely new features: (1) condensation from atomized gas and (2) condensation from mixtures of silicon, oxygen, carbon and hydrogen atoms.