Laboratory Simulation of Magnetospheric Plasma Shocks

Abstract

An experimental simulation of planetary magnetospheres is being developed to investigate the formation of collisionless shocks and their effects. Two experimental situations are considered. In both, the solar wind is simulated by laser ablation plasmas. In one case, the “solar wind” flows across the magnetic field of a high-current discharge. In the other, a transverse magnetic field is embedded in the plasma flow, which interacts with a conductive obstacle. The ablation plasma is created using the “Tomcat” laser, currently emitting 5 J in a 6 ns pulse at 1 μm wavelength and irradiance above 10¹³ W/cm². The “Zebra” z-pinch generator, with load current up to 1 MA and voltage up to 3.5 MV produces the magnetic fields. Hydrodynamic modeling is used to estimate the plasma parameters achievable at the front of the plasma flow and to optimize the experiment design. Particle-in-cell simulations reveal details of the interaction of the “solar wind” with an external magnetic field, including flow collimation and heating effects at the stopping point. Hybrid simulations show the formation of a bow shock at the interaction of a magnetized plasma flow with a conductor. The plasma density and the embedded field have characteristic spatial modulations in the shock region, with abrupt jumps and fine structure on the skin depth scale.