Abstract
Blast-wave-driven hydrodynamic instabilities are studied in the presence of a background B-field through experiments and simulations in the high-energy-density (HED) physics regime. In experiments conducted at the Laboratoire pour l’utilisation des lasers intenses (LULI), a laser-driven shock-tube platform was used to generate a hydrodynamically unstable interface with a prescribed sinusoidal surface perturbation, and short-pulse x-ray radiography was used to characterize the instability growth with and without a 10-T B-field. The LULI experiments were modeled in FLASH using resistive and ideal magnetohydrodynamics (MHD), and comparing the experiments and simulations suggests that the Spitzer model implemented in FLASH is necessary and sufficient for modeling these planar systems. These results suggest insufficient amplification of the seed B-field, due to resistive diffusion, to alter the hydrodynamic behavior. Although the ideal-MHD simulations did not represent the experiments accurately, they suggest that similar HED systems with dynamic plasma-β (=2μ0ρv2/B2) values of less than ∼100 can reduce the growth of blast-wave-driven Rayleigh–Taylor instabilities. These findings validate the resistive-MHD FLASH modeling that is being used to design future experiments for studying B-field effects in HED plasmas.
Highlights
Hydrodynamic instabilities such as Richtmyer–Meshkov (RM), Kelvin–Helmholtz (KH), and Rayleigh–Taylor (RT) have been studied for decades in high-energy-density (HED) plasmas
The l’utilisation des lasers intenses (LULI) experiments were modeled in FLASH using resistive and ideal magnetohydrodynamics (MHD), and comparing the experiments and simulations suggests that the Spitzer model implemented in FLASH is necessary and sufficient for modeling these planar systems
These findings validate the resistive-MHD FLASH modeling that is being used to design future experiments for studying B-field effects in HED plasmas. These mechanisms dominate the late-time behavior of inertial confinement fusion (ICF) implosions1,2 and are prevalent in the evolution of astrophysical systems such as supernovae3,4 and supernova remnants5–7 such as the Crab Nebula
Summary
Hydrodynamic instabilities such as Richtmyer–Meshkov (RM), Kelvin–Helmholtz (KH), and Rayleigh–Taylor (RT) have been studied for decades in high-energy-density (HED) plasmas. These mechanisms dominate the late-time behavior of inertial confinement fusion (ICF) implosions and are prevalent in the evolution of astrophysical systems such as supernovae and supernova remnants such as the Crab Nebula. As high-density spikes fall through the lower-density material, the interface along the spikes is unstable to KH growth. This is often most prominent at the tip of a spike, where the characteristic “mushroom cap” is formed by KH vortices. Magnetic fields present in these hydrodynamically unstable plasmas are predicted to alter this behavior.
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