FLASH Simulations of Laser-Driven Experiments to Investigate Heat Transport in Astrophysical Magnetized Turbulence*

There has been an extended debate about whether the conduction of heat through the tenuous, magnetized plasma that fills galaxy clusters helps to maintain the temperatures of galaxy-cluster cores at much higher values than might be expected given their short radiative cooling times. Although heat conductivity given by the classical Spitzer model suggests that thermal conduction should play a significant role, astronomical observations of temperature fluctuations over much smaller scales than global cluster scales imply strong suppression of heat conductivity compared to the Spitzer value. The precise physical mechanism behind this suppression remains to be understood. Here we present high-fidelity FLASH simulations that were used to design and execute an experimental campaign at the Omega Laser Facility by the TDYNO (Turbulent Dynamo) collaboration, to explore and quantify the suppression of heat conduction in magnetized turbulence. Guided by the FLASH simulations, we were able maximize heat conduction suppression in the magnetized turbulence by introducing heater beams that bring collisional mean free paths to values significantly larger than the plasma Larmor radii. The work builds on our recent breakthrough the National Ignition Facility (NIF), where the strong heat conduction suppression was first demonstrated.