Aachen PK 2003 – scientific programme

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P: Plasmaphysik

P 4: Poster I

P 4.38: Poster

Monday, March 17, 2003, 17:45–19:15, Foyer

Particle manipulation by electrostatic probes in complex plasmas under microgravity — •Markus Klindworth, André Melzer, and Alexander Piel — Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität Kiel, 24098 Kiel

Langmuir probe measurements are highly desirable for the understanding of complex plasmas.Especially under microgravity conditions phenomena like the dust free “void” region or sharply localised dust dynamics are observed, which are not fully understood.Another application of electrostatic probes is the direct manipulation of the charged dust particles.

We have performed excitation and perturbation of particles by Langmuir probe measurements in the PKE plasma chamber which was designed by the MPE for studying complex plasmas under microgravity on parabolic flights. While measuring the probe characteristics the dust surrounding the probe was illuminated by a laser and observed via CCD-cameras.

Interesting effects due to the probe dust interaction can be studied. For example particles are trapped in an voltage dependant equilibrium position around the probe tip, forming shell-like ordered structures. To explain the observations one has to take into account opposite effects like the repulsion of negatively charged dust particles by the negatively biased probe tip and drag force on the dust by ions streaming towards the probe.