Self-Magnetization of Deceleration-Phase Rayleigh-Taylor Growth

Biermann battery magnetic field growth can be driven hydrodynamically, producing magnetic fields strong enough to alter thermal transport in ICF capsules. This project presents results from HYDRA extended-MHD simulations of single-mode and multimode Rayleigh-Taylor growth during deceleration-phase conditions. As the capsule approaches peak-compression during the deceleration-phase, magnetic fields on the order of 5-10kT are injected into the hotspot by the freefalling dense features. The magnetic field growth is driven by rotational acceleration generated through the RT interchange, which produces the misaligned density and temperature gradients necessary for Biermann growth. Magnetic field evolution and structure in the nonlinear stage of RT growth is dependent on competition between ablative fluxes and Nernst advection; this produces a localized pileup of magnetic flux migrating away from the dense RT spike. Reduction of thermal fluxes through Hall parameters of 1-3 cools a 5-10µm region around the spike, creating a volume of low pressure which can accelerate instability growth. Results show the low-pressure volumes contain temperature reductions of 500eV – 1keV in regions surrounding RT structures, with ablated spike mass pulled into the cooled region and injected into the hotspot. The injection of this cooled mass into inertial fusion hotspots along with Righi-Leduc thermal fluxes increasing hot electron flux out of the hotspot can potentially reduce experimental performance.