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Experiments with extended three-dimensional dusty plasmas under microgravity conditions were performed to study the complex wave pattern of self-excited dust-density waves and its interaction with the plasma. The simultaneous observation of the dust-density fluctuations and the plasma glow revealed that the observed wave phenomenon affects the plasma in the complete discharge. In particular, our investigations suggest, that self-excited dust-density waves are the product of a self-organized system consisting of the dust cloud, the plasma, and the external circuit. The complex wave pattern is a consequence of partial synchronization of neighboring regions inside the dust cloud and can be modeled by a system of coupled nonlinear oscillators. [ABSTRACT FROM AUTHOR]

Laboratory experiments with thermophoretic levitation of dust particles for gravity compensation are reported. The observed spatially extended dust clouds were investigated, e.g., the dependence of discharge parameters on the void structure. These investigations lead to the discovery of an extended parameter region where spatially extended void-free clouds can be found. The mechanism of void closure is accompanied by a spontaneous change in the discharge topology. This change becomes evident from a reversal of the wave propagation direction. [ABSTRACT FROM AUTHOR]

A chain of mutually coupled nonlinear and self-sustained oscillators is studied numerically. The simple model allows to explain the topological structure of self-excited dust-density waves under microgravity conditions. The basic properties of the model are presented and compared with experimental studies. [ABSTRACT FROM AUTHOR]