Hannover 2010 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 23: Poster II

A 23.53: Poster

Donnerstag, 11. März 2010, 16:30–19:00, Lichthof

Collective modes of ultracold neutral plasmas — •Andrei Lyubonko, Thomas Pohl, and Jan-Michael Rost — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

We study collective modes in an ultracold neutral plasma (UNP), as observed in recent experiments via microwave excitation of plasma electrons. The absence sharp boundary in freely expanding UNPs requires different approaches than used to understand the response of confined hot plasmas, but suggests an analogy to the behavior of hot stars.

We present extensive molecular dynamics simulations that reproduce experimental observations, upon a proper inclusion of temperature and charge imbalance effects. In contrast to previous believe, the calculations show that the found high-order resonances are not of Tonks-Dattner type. We elucidate the nature of these unusual modes, based on a hydrodynamical theory. Upon proper understanding such modes can serve as diagnostic tool to monitor the plasma temperature and other properties, such as the degree of neutrality during the expansion of ultracold plasmas.