ionization, ion, plasma, ultracold, Coulomb
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).
BYU ScholarsArchive Citation
Lyon, M.; Bergeson, Scott D.; Diaw, A.; and Murillo, M. S., "Using Higher Ionization States to Increase Coulomb Coupling in an Ultracold Neutral Plasma" (2015). Faculty Publications. 1838.
American Physical Society
Physical and Mathematical Sciences
Physics and Astronomy
© 2015 American Physical Society. This article is the Version of Record published by the American Physical Society in Physical Review E in 2015, available online at https://doi.org/10.1103/PhysRevE.91.033101
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