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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]

The dynamical properties of individual particles in a dusty plasma under microgravity conditions are investigated by means of a stereoscopic camera setup. This camera system allows the three-dimensional reconstruction of particle trajectories in a volume of approximately (15×15×15) mm3 in three dimensions. We present measurements in two different regions of a dust cloud on parabolic flights. First, the force field in the void is reconstructed from probe particles in three dimensions. Second, the oscillation of particles at the outer dust cloud surface is evaluated, and the relation to dust-density waves in the dust cloud is investigated. [ABSTRACT FROM AUTHOR]

Dusty plasmas have been confined by glass walls in order to generate void-free particle structures under microgravity conditions. Different types of clouds establish in the cuvette in dependence on the rf power and dc bias applied to the multi-electrode system of the discharge device. The observations can be basically understood when applying standard force models to discharge simulation results. The various dust topologies are proposed to result from a change in the direction of the ion drag — inwards or outwards the cuvette gap. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The interaction of a supersonic projectile with a static dust cloud trapped in an rf discharge under microgravity conditions is examined. It is observed that the projectile forms a dust-free cavity in its wake. The cavity dynamics can be divided into an initial impulse and a subsequent elastic response that can be modeled by a damped harmonic oscillator. [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]