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Recently [1-3], the possibility of the formation of dust structures in cryogenic environment at 4.2-77 K was investigated. It was revealed from the experiments that the dust structures with high concentration of dust particles can be formed (so-called superdense dusty plasma structures), in which interparticle distance is comparable with particle size. Such formations had exotic properties such as spherical (globular) configuration, free boundaries, etc. In the present work new results on the experimental investigations of spheroidizing-phenomenon of the transition of dust structures to compact globular (spherical) shape at cryogenic temperatures-were presented. The experiments were made by means of recently developed techniques and new cryogenic facilities (optical helium cryostat). Possible nature of such phenomenon is discussed. [ABSTRACT FROM AUTHOR]

Results of experimental investigations of instabilities in cryogenic DC discharge were presented. Different types of dusty plasma instabilities (self-excited oscillations, vortices and complex oscillations) were observed. The dependence between frequencies of oscillations and the gas pressure for structures with self-excited oscillations at temperatures from 10 to 300 K was obtained. It was revealed that decreasing of gas temperature can lead to damping of self-excited oscillations. A relative gradient of the particles charge causing the dusty plasma instabilities was estimated. [ABSTRACT FROM AUTHOR]