Numerical Investigations of Plasma Rayleigh-Taylor Instability in ICF Coasting Stage

Accurate simulations of Rayleigh-Taylor instability (RTI) with realistic transport phenomena have been conducted under ICF coasting stage conditions by using a high-order two-fluid plasma solver (Li and Livescu, Phys. Plasmas 26, 012109, 2019). The numerical results show that, for any given Atwood number and hot-spot temperature, the RTI development or lack thereof can be characterized by two critical hot-spot number densities, which increase exponentially with hot-spot temperature and decrease with Atwood number. When the hot-spot number density is smaller than the lower threshold value, RTI is completely suppressed by the electron thermal diffusion and viscous dissipation. Instead, fully developed RTI into chaotic stage (single-mode) or turbulence (multimode) is observed only when the hot-spot number density is larger than the upper threshold value. Though a strong magnetic field (B~10³T) is created by the Biermann battery effect, and its magnitude increases with Atwood number, for all simulations conducted in this study, the self-generated magnetic field is not sufficient to affect the flow dynamics or inhibit the electron thermal conduction because of the extremely large plasma beta (β~10⁵) and small product (x~10^-2) of electron cyclotron frequency and collision time.