Berlin 2005 – wissenschaftliches Programm
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SYPS: Plasmen in ungewöhnlichen Situationen
SYPS 1: Symposium: Plasmas in unusual situations, Part I: Ultracold plasmas
SYPS 1.1: Hauptvortrag
Montag, 7. März 2005, 10:30–11:00, HU Audimax
Ultracold Neutral Plasmas — •Thomas Killian — Department of Physics and Astronomy, Rice University, Houston, Texas, USA
Ultracold neutral plasmas [1], formed by photoionizing laser-cooled atoms near the ionization threshold, stretch the boundaries of traditional neutral plasma physics. The electron temperature in these plasmas is from 1-1000K and the ion temperature is around 1 K. The density can be as high as 1010 cm−3. Fundamental interest stems from the possibility of creating strongly-coupled plasmas, but recombination, collective modes, and thermalization in these systems have also been studied.
The ultracold plasma group at Rice University recently demonstrated optical absorption imaging of a strontium plasma [2] using the Sr+ 2S1/2 → 2P1/2 transition at 422 nm. Images depict the density profile of the plasma and probe kinetics on a 50 ns time-scale. The Doppler-broadened ion absorption spectrum measures the ion velocity distribution, which gives an accurate measure of the ion dynamics in the first few hundred nanoseconds after photoionization.
Current work focuses on kinetic energy oscillations during plasma equilibration and developing the tools to laser cool and trap the plasma. This work is supported by the Department of Energy, National Science Foundation, Alfred P. Sloan Foundation, Research Corporation, and David and Lucille Packard Foundation.
[1] T. C. Killian, S. Kulin, S. D. Bergeson, L. A. Orozco, C. Orzel, and S. L. Rolston, Phys. Rev. Lett. 83, 4776 (1999). [2] C. E. Simien, Y.C. Chen, P. Gupta, S. Laha, Y. N. Martinez, P. G. Mickelson, S. B. Nagel, T. C. Killian, Phys. Rev. Lett. 92, 143001 (2004).