A Plasma Dynamo Experiment For Studying Astrophysically Relevant Flow Driven MHD Instabilities

Type Journal Article
Names C. Forest, E. G. Zweibel, N. K. Katz, E. J. Spence, M. Nornberg, I. Khalzov, C. Collins, D. Weisberg, J. Wallace, J. Jara-Almonte, M. Clark
Publication AGU Fall Meeting Abstracts
Volume 51
Pages 05
Date December 1, 2010
URL http://adsabs.harvard.edu/abs/2010AGUFMNG51C..05F
Library Catalog NASA ADS
Abstract Many astrophysical objects, like the Sun, are composed of high magnetic Reynolds number, turbulent, flowing plasma in which the flow energy is much larger than that of magnetic field. Creating such conditions in laboratory plasma experiments is challenging since confinement is usually required to keep the plasma hot (and conducting) which is typically achieved by using strong applied magnetic fields. For this reason, laboratory experiments using liquid metals have been addressing fundamental plasma processes in this unique parameter regime. This talk will begin by reviewing self-generation of a magnetic field of energy comparable to the turbulent flow from which it arises--the dynamo process. Liquid metal experiments have (1) demonstrated self-excitation of magnetic fields, (2) two scale dynamos where a small scale flow drives a large scale magnetic field, (3) intermittent self-excitation and a variety of time dynamics including field reversals, and (4) showed the existence of a turbulent electromotive force (mean-field current generation). Liquid metals are, however, not plasmas: dynamos may differ in plasmas where the relative importance of viscosity and resistivity can be interchanged, and new instability mechanisms, outside the scope of incompressible MHD may be critical in plasmas. This suggests that the next generation of experiments in this important astrophysics regime should be based upon plasmas. The Madison Plasma Dynamo experiment (now under construction) will then be described with an overview of the concept and show how the dynamos might operate in this plasma. Modeling of several experimental scenarios that mimic solar processes will also be described, including experiments on rotating, compressible convection driven by magnetic buoyancy.
Tags [0654] ELECTROMAGNETICS / Plasmas, [4490] NONLINEAR GEOPHYSICS / Turbulence, [5734] PLANETARY SCIENCES: FLUID PLANETS / Magnetic fields and magnetism
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