H. Hoefner | Searcharxiv

arXiv2008

Convective dust clouds in a complex plasma

The plasma is generated in a low frequency glow discharge within an elongated glass tube oriented vertically. The dust particles added to the plasma are confined above the heater and form counter-rotating clouds close to the tube centre. The shape of the clouds and the velocity field of the conveying dust particles are determined. The forces acting on the particles are calculated. It is shown that convection of the dust is affected by the convective gas motion which is triggered, in turn, by thermal creep of the gas along the inhomogeneously heated walls of the tube.

physics.plasm-ph↗

arXiv2004

Measurement of the Ion Drag Force in a Complex DC-Plasma Using the PK-4 Experiment

The force on a microparticle in a complex plasma by streaming ions, the so-called ion drag force, is not well known. However, it is important for the understanding of interesting phenomena in complex plasmas such as the void formation under microgravity conditions. The PK-4 experiment, which is developed for a later use on board of the International Space Station, is ideally suited for investigating this problem. In this experiment a complex DC-plasma is created in a glass tube in which the microparticles flow from the cathode to the anode. Measuring the microparticle velocities, the forces on the particles for different particle sizes, pressures, and DC-currents can be extracted by assuming force balance. Experiments have been performed in the laboratory as well as under microgravity using parabolic flights. The results of these experiments will be presented and compared to theoretical predictions.

physics.plasm-ph↗