Keywords

ionization, ion, plasma, ultracold, Coulomb

Abstract

We report measurements and simulations of the time-evolving rms velocity distribution in an ultracold neutral plasma. A strongly coupled ultracold neutral Ca+ plasma is generated by photoionizing laser-cooled atoms close to threshold. A fraction of these ions is then promoted to the second ionization state to form a mixed Ca+-Ca2+ plasma. By varying the time delay between the first and the second ionization events, a minimum in ion heating is achieved. We show that the Coulomb strong-coupling parameter Γ increases by a factor of 1.4 to a maximum value of 3.6. A pure Ca2+ plasma would have Γ=6.8, moving these strongly coupled systems closer to the regime of liquid-like correlations.

Original Publication Citation

M. Lyon, S. D. Bergeson, A. Diaw, and M. S. Murillo. Using higher ionization states to increase Coulomb coupling in an ultracold neutral plasma. Phys. Rev. E 91 (3), 033101 (2015).

Document Type

Peer-Reviewed Article

Publication Date

2015

Publisher

American Physical Society

Language

English

College

Physical and Mathematical Sciences

Department

Physics and Astronomy

Included in

Physics Commons

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