Reversal of Microparticle Motion at the Onset of Polarity Switching in Ground-Based PK-4 Experiments

The behavior micron-sized particles (dust) in a plasma system are of great interest, both as a model system for studying a wide range of physics and in practical applications. In ground-based experiments, the high mass of the dust leads to sedimentation effects. To reduce sedimentation effects, it is necessary to perform experiments in a microgravity environment, such as in the ISS based experiment facility "Plasma-Kristall-4" ("PK-4"). In the PK-4 facility, particles are injected into a dc glow discharge plasma and flow along an axial electric field. Upon the application of polarity switching (a periodic oscillation of the electric field), a sudden change in the bulk motion and spatial ordering of the dust is observed. This poster will present the results of a study of the thermal state of dust particles within the PK-4 experiment as the frequency of polarity switching is varied.