Layered structures in extended dust clouds under microgravity

Abstract

Three dimensional particle clouds in a plasma environment have been studied under microgravity conditions on parabolic flights. By using a stereoscopic 4-camera system, it was possible to reconstruct the three-dimensional particle motion in a selected volume. From this, a layered structure in the dust-cloud is revealed that is not observable with plain two-dimensional diagnostics. The spacing between the layers is found to be decisively larger than the interparticle distance inside the layer. This layered structure is observed in different situations, with and without waves. Further, it has been found that the position of the layers is stationary in the plasma even though the particles show an overall motion. The origin of the layer formation is discussed.