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P: Plasmaphysik

P 17: Postersitzung: Plasma-Wand-Wechselwirkung III, Grundlegende Probleme Theorie II, Schwerionen- Laserplasmen II, Dichte Plasmen II

P 17.11: Poster

Mittwoch, 10. März 2004, 17:45–19:30, Foyer

Mitigating Disorder-Induced Heating in Ultracold Plasmas^* — •D.O. Gericke and M.S. Murillo — Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

Recent experiments demonstrated the creation of ultracold plasmas by ionization of trapped atoms with temperatures in the µK range [1,2]. The initial ion properties correspond to a very strongly coupled state; therefore, ultracold plasmas could provide a new avenue to investigate strong coupling effects with relatively long lived samples.

Unfortunately, the build up of correlations strongly heats the ions [3]. We show how this process is related to the establishment of Coulomb structure in the final plasma state and give results for the amount of disorder-induced heating for a wide variety of initial conditions. Since the ions gain a large amount of kinetic energy while building up negative potential energy, plasmas are usually heated to a moderately coupled state that is almost independent of the initial temperature [4]. Two possibilities for reducing the heating by the introduction of structure in the initial state, i.e., the gas before ionization, are then discussed: the ionization of a highly degenerate gas of fermionic atoms and the ionization of highly excited atoms in Rydberg states.

[1] T.C. Killian et al., Phys. Rev. Lett. 83, 4776 (1999).

[2] M.P. Robinson et al.; Phys. Rev. Lett. 85, 4466 (2000).

[3] M.S. Murillo, Phys. Rev. Lett. 87, 1150031 (2001).

[4] D.O. Gericke & M.S. Murillo, Contrib. Plasma Phys. 43, 298 (2003).

^*funded by the U.S. Department of Energy (contract W-7405-ENG-36)