Plasma Physics (Physics/ECE/NE 922) Seminars

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Numerical modeling of magnetic self-organization at the top of the solar convection zone
Date: Monday, March 11th
Time: 12:05 pm
Place: 2241 Chamberlin Hall
Speaker: John O'Bryan, University of Washington-Seattle
Abstract: Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization near the narrow, convectively unstable super-adiabatic layer at the top of the solar convection zone. The convective turbulence produced by the super-adiabatic rapidly saturates with kinetic and magnetic energy fluctuations in equipartition. Magnetic self-organization produces a radially-localized, latitudinally-elongated magnetic structure. The convective turbulence drive is stabilized by magnetic field, which limits the achievable magnetic field from localized turbulence alone. Differential rotation of the sun creates an inductive electric field which also causes growth of the magnetic field within the structure, the rate of which scales with its magnitude. The saturated small-scale turbulence can also drive a large-scale dynamo through the magnetic shear-current effect. When considered together, the localized convective turbulence and rotational flow shear create a robust mechanism for magnetic field generation, regardless of its magnitude. The nonlinear evolution of such a shallow magnetic structure may provide insight into the evolution of surface magnetic features.
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