The Interaction of Low-Frequency Turbulence with Collisionless Shock Waves

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Shock waves and low-frequency turbulence are ubiquitous in plasmas, occurring in environments as diverse as jet engines, inertial confinement fusion devices, interplanetary space, the Earth's bow-shock and supernovae. The fundamental interactions between shocks and turbulence will be addressed through two complementary studies. For situations in which pre-existing upstream turbulence is simply convected into a shock, the mean location and speed of the shock as a function of the upstream energy density and turbulence, the variance of the shock position and speed, the amplification of the turbulence by the shock and its subsequent dissipation downstream will all be assessed through sophisticated numerical simulations. Broad energetic-particle-mediated shocks amplify and transmit the pre-existing turbulence, but also generate additional turbulence through shock-accelerated energetic particle gradients. In this case, energetic particles can contribute to the overall momentum balance within the shock. The second study aims at developing a fully self-consistent model of the thermal plasma, the superthermal accelerated particles and the associated magnetohydrodynamic turbulence through a shock jump.