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Center for Nonlinear Studies |
It has long been expected that Rayleigh-Taylor instabilities in ICF implosions can generate magnetic fields. To investigate this, a Hall-MHD model is used with the discontinuous Galerkin method in the code, WARPX (Washington Approximate Riemann Plasma). 2-D single-mode and multi-mode studies of a Rayleigh-Taylor instability are performed in a stratified two-fluid plasma. Self-generated magnetic fields are observed and these fields grow (to over 100 T) as the Rayleigh-Taylor instability progresses. The thermoelectric term in the generalized Ohm's law is responsible for the formation of a self-generated magnetic field. In the absence of this term in Ohm's law, no magnetic field forms. Scaling studies are performed to determine the growth of the self-generated magnetic field as a function of density, gravity, Atwood number, and perturbation wavelength. The magnetic field increases as the wavelength decreases, and as gravity increases, which is consistent with theory. A heuristic model is developed for the magnetic field as a function of Rayleigh-Taylor parameters and an estimate of the Hall parameter is provided.
Host: Shiv K. Sambasivan, T-5 665-8075