Self-sustained levitation of dust aggregate ensembles by temperature-gradient-induced overpressures.
In laboratory experiments we observe dust aggregates from 100 mum to 1 cm in size composed of micrometer-sized grains levitating over a hot surface. Depending on the dust sample aggregates start to levitate at a temperature of 400 K. Levitation of dust aggregates is restricted to a pressure range between 1-40 mbar. The levitating is caused by a Knudsen compressor effect. Based on thermal transpiration through the dust aggregates the pressure increases between surface and aggregates. Dust aggregates are typically balanced approximately 100 microm over the surface. On a slightly concave surface individual aggregates are trapped at the center. Ensembles of aggregates are confined in a 2D plane. Aggregates are subject to systematic and random translational and rotational motion. The levitated aggregates are well suited to study photophoretic or thermophoretic forces or the mutual interaction between dust aggregates.
Kelling
Thorben
T
Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany. thorben.kelling@uni-muenster.de
Wurm
Gerhard
G