Enhanced collisionless shock formation in a magnetized plasma containing a density gradient

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Enhanced collisionless shock formation in a magnetized plasma containing a density gradient

S. E. Clark, E. T. Everson, D. B. Schaeffer, A. S. Bondarenko, C. G. Constantin, C. Niemann, and D. Winske

Phys. Rev. E 90, 041101(R) – Published 17 October 2014

Abstract

Two-dimensional hybrid simulations of super-Alfvénic expanding debris plasma interacting with an inhomogeneous ambient plasma are presented. The simulations demonstrate improved collisionless coupling of energy to the ambient ions when encountering a density gradient. Simulations of an expanding cylinder running into a step function gradient are performed and compared to a simple analytical theory. Magnetic flux probe data from a laboratory shock experiment are compared to a simulation with a more realistic debris expansion and ambient ion density. The simulation confirms that a shock is formed and propagates within the high density region of ambient plasma.