Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 18: Poster: Diagnostics

P 18.20: Poster

Donnerstag, 11. März 2010, 16:00–18:00, Lichthof

Measurement of the Drag Force on Microparticles in an Energetic Ion Beam — Viktor Schneider, •Thomas Trottenberg, and Holger Kersten — Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel

In complex (dusty) plasmas the coexistence of microparticles and streaming ions is a common situation, e.g. in natural environments in space, in laboratory plasmas and in technological applications.

A new experiment for the study of forces on microparticles in an ion beam is presented. A 125 mm broad beam ion source provides a vertically upward directed beam of several hundreds of eV wherein hollow glass spheres (∼100µm) are injected. The particles are illuminated by a diode laser and their trajectories are recorded with a ccd camera. From the trajectories the acceleration and the net force on the particles are determined. The experimental setup allows a measurement of the momentum transfer due to the two possible mechanisms, i.e. ion-dust and fast-neutral-dust collisions (the fast neutrals stem mainly from charge-exchange collisions). If the ion beam current density and the ion velocity distribution are known, the net force can be attributed quantitatively to the two mechanisms.

The experimental situation differs in essential aspects from typical dusty plasma experiments, where the ion energies are mostly in the order of room temperature thermal energies (<1eV), and the ion velocities are rather isotropically distributed than directed (subthermal ion drift).