Bulletin of the American Physical Society
50th Annual Meeting of the Division of Plasma Physics
Volume 53, Number 14
Monday–Friday, November 17–21, 2008; Dallas, Texas
Session AR0: Celebration of Plasma Physics Plenary Presentations I |
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Chair: Thomas Antonsen, University of Maryland Room: Landmark A/B |
Monday, November 17, 2008 8:00AM - 8:36AM |
AR0.00001: Magnetic Confinement: Establishing the Principles through Experiment Invited Speaker: In the past fifty years, the quality of magnetic confinement (the product of density x temperature x confinement time) has increased by a factor of 100,000. Fueling this evolution is the development of robust physics principles, from single particle behavior to turbulence. These principles have evolved through experiments in many configurations, and continue to stimulate progress in plasma confinement. Early appreciation of the constraining effect of symmetry on single particle motion yielded a focus on axisymmetric tori; today, symmetry ideas appear in 3D stellarator experiments with the new ingredient of quasi-symmetry. Collecting particles into an MHD equilibrium has become routine for a wide range of plasma structures. Specially tailored equilibria are now produced by wave-driven and pressure-driven (bootstrap) currents. The principle of favorable magnetic curvature for stability has been established and exploited in many configurations; recently, high plasma pressure is obtained in the spherical tokamak by enhancement of good toroidal curvature. But plasma stability can be interrupted by magnetic reconnection events that scramble the magnetic field, forcing fusion experiments to unravel the physics of reconnection. Early experiments revealed the ubiquity of turbulence that degrades confinement. Now, turbulence is partly controlled, from electrostatic turbulence in tokamaks to magnetic turbulence in reversed field pinches. All these principles combine in the grand experiment of our era: ITER, a burning plasma with fusion-produced alpha particles confined in shaped plasma equilibria, with favorable average curvature, assisted by wave-driven and bootstrap currents, situated in turbulence reduced by flow shear. And experiments continue to advance, with no sign of saturation, the physics of tokamaks and the broad spectrum of other magnetic configurations. [Preview Abstract] |
Monday, November 17, 2008 8:36AM - 9:12AM |
AR0.00002: Nonneutral Plasmas and the Wider World of Physics Invited Speaker: Basic research with nonneutral plasmas has been rich in interdisciplinary connections to the wider world of physics. For example, the creation of laser cooled pure ion crystals involved a combination of ideas from plasma physics and condensed matter physics and experimental techniques from atomic physics. The collaboration of plasma physicists and atomic physicists on studies of these small Penning trap plasmas, liquids, crystals has been an interdisciplinary success story, yielding what are arguably the best understood and best controlled plasmas systems in existence. Current research with these plasmas is attempting to model fusion reactions in correlated dense matter. Another example is the use of magnetically confined pure electron plasma systems to model the 2D incompressible and inviscid flow of ordinary neutral fluids. The precision of 2D vortex dynamics experiments, such as vortex merger, can be higher than with water tanks because the plasma flow is of very low viscosity and is not influenced by a boundary layer at the bottom of the tank. Surprisingly, for certain initial conditions, the decay of 2D turbulence is found to result in a 2D vortex crystal, similar to the 2D vortex crystals observed in other systems, such as superconductors and superfluids. Plasma physicists, atomic physicists, and particle physicists are collaborating at CERN to produce cold antihydrogen for basic physics studies. In these experiments a cryogenic positron plasma and a cryogenic antiproton plasma are mixed, yielding antihydrogen through rapid three body recombination. The experiments generate many interesting theory challenges at the interface of plasma physics and atomic physics. For example, the antihydrogen atoms formed initially are weakly bound and strongly magnetized, and guiding center drift theory provides a natural description of the positron orbit in the atom. Thus, these novel atoms, now called guiding center drift atoms, are rendered integrable using orbit dynamics developed in plasma physics. [Preview Abstract] |
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