Effect of background magnetic fields on magnetised, collisionless shocks.

Magnetized collisionless (λ_mfp>> L_shock) shocks are created throughout the universe including within super-nova remnants and the Earth’s atmosphere. When these shocks propagate into a magnetised background plasma where fields are aligned perpendicular to the flow velocity, density perturbations and voids can be produced as the fields pile-up ahead of the shock front. The understanding of the influence of the magnitude of the background magnetic field on the shock formation and the resulting structures has recently been investigated using a laboratory experiment. The results assist in benchmarking HANE (High Altitude Nuclear Explosion) models, as well as supporting HYDRA simulations, to develop a better understanding of the underlying physics.



The experiments were conducted using the Omega laser where a gas jet provides a pre-ionized, pre-magnetized background plasma within a MIFED assembly, through which the shock is driven. The effect of the magnitude of the background magnetic fields on the shock formation is primarily diagnosed using both temporally and spatially resolved Thomson scattering. Proton probing also assisted in understanding the magnetic field structures produced. This presentation will discuss experimental results as well as comparisons with HANE and HYDRA simulations.