| Description | Abstract:
Nonneutral plasmas consisting of particles with only a single sign
of charge (e.g., pure electron, pure positron, or pure ion plasmas) can
be confined for days or even weeks using the static electric and
magnetic fields of a Penning trap. These novel plasma systems can
access regimes unavailable to neutral plasmas. For instance, they have
been cooled to cryogenic temperatures without recombination, where they
can form strongly-coupled nonneutral liquid or crystalline states. Theory and experiments have explored
the structure of these novel condensed matter systems. Also, they are confined by
strong magnetic fields, allowing access to several novel strongly-magnetized regimes. In one such regime,
where the plasma is strongly magnetized but weakly-coupled,
the cross-magnetic field thermal conductivity is predicted and observed to be independent of magnetic field strength,
a surprising result. In a second strongly-magnetized and strongly-coupled regime, the interparticle
collision physics can be fruitfully compared to nuclear reactions in high energy
density astrophysical plasmas such as those found in
the interior of a supernova progenitor. This comparison has allowed the first laboratory measurements of
dense plasma enhancements to nuclear reaction rates.
References:
D. Dubin and T. O'Neil, "Trapped nonneutral plasma, liquids and crystals (the thermal equilibrium states), Rev. Mod. Phys. 71, 87 (1999)
T. B. Mitchel et al., "Direct Observations of Structural Phase Transitions in Planar Crystallized Ion Plasmas", Science 282, 1290 (1998)
E. M. Hollman, F. Anderegg and C. F. Driscoll, "Measurement of Cross-Magnetic Field Heat Transport in a Pure Ion PLasma, Phys. Rev. Lett. 82, 4839 (1999)
D. Dubin, "Modelling Nuclear Fusion in Dense Plasmas Using a Cryogenic Nonneutral Plasma", Phys. Plasmas 15, 055705 (2008)
F. Anderegg et al., "Mesaurment of Correlation-Enhanced Collision Rates Using Pure Ion Plasmas:, Phys. Plasmas 17, 055702 (2010)
Bio:
Dr. Dubin completed his undergraduate degree in theoretical physics in 1978 at Queen's University in Kingston, Ontario. He then enrolled in the plasma physics program at Princeton University. Dr. Dubin then joined the nonneutral plasma group at the University of California, San Diego. His chief research interest is the basic physics of nonneutral plasmas. This has led to investigations in several related areas, including 2D fluid dynamics, dusty plasmas, nonequilibrium statistical physics, and structural condensed matter physics. Dr. Dubin is now a professor in the physics department at UCSD. He is a Fellow of the American Physical Society and a recipient of the John Dawson Award for Excellence in Plasma Physics Research.
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