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P: Fachverband Plasmaphysik

P 23: Helmholtz Graduate School for Plasma II

P 23.1: Fachvortrag

Donnerstag, 3. März 2016, 14:30–14:55, b302

Investigating structure and dynamics of Yukawa-balls — •Matthias Mulsow and André Melzer — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald

The aim of this talk is to give an overview on our current research in the field of Yukawa-balls. These three-dimensional strongly coupled systems usually consist of less than one hundred micron-sized particles. By using a harmonic trapping potential they form spherical, crystal-like structures in the plasma sheath region.

In order to investigate their structural and dynamical properties, we developed a new experimental setup. Its centerpiece is a segmented confinement ring that provides us with a trapping potential without disturbing the visual observation. By applying electrical potentials to the ring segments it is possible to modulate fluid mode oscillations onto the cluster. With a slightly modified version of the ring the confinement potential can also be switched off in two spacial directions, inducing a uniform expansion of the cluster. The characteristic expansion behavior is then compared with theoretical prediction [1].

Furthermore, as an example of cluster thermodynamics we have studied structural transitions and analyzed them in terms of configurational Shannon entropies and associated specific heat capacities, as proposed in [2].

The talk will present the new methods mentioned above in detail and put them into perspective.

[1] A. Piel and J. A. Goree, Phys. Rev. E 88, 063103 (2013)

[2] H. Thomsen and M. Bonitz, Phys. Rev. E 91, 043104 (2015)