Bochum 2015 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 16: Poster Session - Helmholtz Graduate School for Plasma Physics
P 16.21: Poster
Dienstag, 3. März 2015, 16:30–18:30, Foyer Audimax
Experimental investigation of specific heat in finite 3D Yukawa-balls — •Matthias Mulsow1, André Schella2, and André Melzer1 — 1Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald — 2Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen
In low-temperature plasmas micrometer-sized particles are able to form highly ordered structures. Using a harmonic three-dimensional trapping potential strongly coupled finite systems can be created, the Yukawa-balls. The characteristic crystal-like structure and its phase transitions during heating can be quantified by the center-two-particle correlation function (C2P) and the triple correlation function (TCF). While the C2P takes all particles of the spherical cluster into account, the TCF is computed for each shell individually.
Recently it was shown by Thomsen and Bonitz  that reduced Shannon entropies and reduced specific heats can be derived from these distribution functions. The authors used the latter to identify the onset of the well known radial melting on the one hand but also discovered new intrashell structural transitions in the specific heats associated with the C2P.
To investigate these predictions experimentally, spherical Yukawa-balls are observed at different temperatures to which they are tuned by heating lasers. This poster presents the current status and results of these observations in order to verify the new structural transitions.
 H. Thomsen and M. Bonitz, arXiv:1410.2393v1 (2014)