Stuttgart 2012 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 6: Correlation dynamics in plasmas and clusters II
A 6.1: Hauptvortrag
Montag, 12. März 2012, 14:00–14:30, V57.01
Equilibration of Strongly Coupled Ultracold Plasmas — •Thomas Killian — Rice University, Houston, Texas, USA
Ultracold neutral plasmas provide a powerful platform for studying collisional equilibration in strongly coupled systems. They are created by photoionizing laser-cooled atoms at the ionization threshold, and the resulting ion and electron temperatures are orders of magnitude colder than in traditional neutral plasmas. The ions are strongly coupled and equilibrate with Coulomb coupling constant 1< Γi < 4. Because the density is relatively low compared to high-density strongly coupled plasmas, all relevant timescales are much longer, which provides great advantages for experiments.
The creation of the plasma involves a rapid hardening, or quench of the particle interactions. This leads to an exchange of potential and kinetic energy during subsequent thermalization called correlation induced heating. This is followed by oscillations of the kinetic energy at the ion plasma oscillation frequency. It is also possible to perturb the velocity distribution in an equilibrium plasma and observe the relaxation to a Maxwell-Boltzmann distribution. This allows a measurement of the collision rate in the strongly coupled regime, beyond the point where standard Landau-Spitzer theory becomes invalid. Both experiments probe general features of equilibrating strongly coupled systems and can be related to dynamics in other laser-produced plasmas.