Self-Generated Magnetic Field Growth During Deceleration-Stage Rayleigh-Taylor Mixing

The Rayleigh-Taylor instability occurs during the deceleration stage of inertial confinement fusion implosions, in which turbulent mixing injects plasma from the colder outer shell into the hotspot. The interchange between the high and low-density fluids generates a growing vorticity, forming non-parallel temperature and density gradients which drive Biermann battery magnetic field growth [1]. The magnetic field forms azimuthally around the free-falling dense spike, and is compressed against the spike by the Nernst effect [2], [3]. With sufficient magnetization, outward-moving hotspot electrons will be deflected away from the tip of the spike to form a colder, lower pressure region of plasma which will accelerate the spike. It is believed the Rayleigh-Taylor instability can magnetize the hotspot of inertial confinement implosions, where the accelerated growth could lead to reduced symmetry and lower yields [2]. A computational study of the relationship between the Biermann battery and Rayleigh-Taylor instability is presented. The presence of vorticity in the linear and late non-linear stage is studied as the main driver of magnetic field growth, and the contribution of multiple extended-MHD effects such as Nernst advection, the Hall effect, and Righi-Leduc flux are reviewed using the HYDRA MHD code. [1] B. Srinivasan and X.-Z. Tang, Physics of Plasmas, 19, 082703 (2013); [2] C. A. Walsh and D. S. Clark, Phys. Rev. E, 107, L013201, (2023); [3] D. Zhang, J. Li, J. Xin et. al, Physics of Plasmas 29, 072702. LLNL-ABS-866252