Dresden 2011 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 26: Poster III
A 26.78: Poster
Donnerstag, 17. März 2011, 16:00–18:30, P2
Ion - ion collisions in strongly coupled ultracold plasmas — •Georg Bannasch1, Thomas Pohl1, Jose Castro2, Patrick McQuillen2, and Thomas Killian2 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden — 2Physics & Astronomy Department, Rice University, Houston, USA
Collisions between charged plasma particles are often described by the famous Spitzer collision rate [1]. The Spitzer theory is based on the assumption that the Debye screening length is larger than the mean interparticle distance, i.e. that the plasma is weakly coupled. Laboratory-based ultracold plasmas, on the other hand, grant experimental access to the strong coupling regime, in which the Spitzer collision rate may diverge.
Here, we present a joint experimental theoretical study of ion - ion collisions in such an ultracold plasma. Velocity-selective optical pumping combined with fluorescence measurements permits to observe the dynamics of velocity relaxation on relevant timescales. In addition, we present exhaustive molecular dynamics simulations that yield good agreement with the experiment, and combined with a statistical description allow to characterize the collision rate at the onset of correlations and deep in the strongly coupled regime.
[1] Jr. L. Spitzer. Physics of Fully Ionized Gases. Wiley, New York, 1962