Strong Suppression of Heat Conduction in Laser-Driven Magnetized Turbulent Plasmas

Astronomical observations of galaxy-cluster cores reveal temperatures that are significantly higher than expected from the relatively short radiative-cooling time scales. While the central active galactic nuclei are thought to provide most of the heating, the presence of stochastic magnetic fields at equipartition with the kinetic energy of the turbulent motions is expected to impact thermal transport. We present laser-driven experiments by the Turbulent Dynamo collaboration at LLNL’s National Ignition Facility that realize magnetized turbulence and plasma properties relevant to those in galaxy clusters. The experiments, designed with high-fidelity FLASH simulations, demonstrate a strong suppression of local heat transport by two orders of magnitude or more. The suppression results in pronounced temperature fluctuations at small spatial scales, akin to the cold fronts observed in galaxy-cluster plasmas.