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Title: Shocks in unmagnetized plasma with a shear flow: Stability and magnetic field generation

A pair of curved shocks in a collisionless plasma is examined with a two-dimensional particle-in-cell simulation. The shocks are created by the collision of two electron-ion clouds at a speed that exceeds everywhere the threshold speed for shock formation. A variation of the collision speed along the initially planar collision boundary, which is comparable to the ion acoustic speed, yields a curvature of the shock that increases with time. The spatially varying Mach number of the shocks results in a variation of the downstream density in the direction along the shock boundary. This variation is eventually equilibrated by the thermal diffusion of ions. The pair of shocks is stable for tens of inverse ion plasma frequencies. The angle between the mean flow velocity vector of the inflowing upstream plasma and the shock's electrostatic field increases steadily during this time. The disalignment of both vectors gives rise to a rotational electron flow, which yields the growth of magnetic field patches that are coherent over tens of electron skin depths.
Authors:
; ;  [1] ; ; ; ;  [2]
  1. Department of Science and Technology, Linköping University, SE-60174 Norrköping (Sweden)
  2. Centre for Plasma Physics (CPP), Queen's University Belfast, BT7 1NN (United Kingdom)
Publication Date:
OSTI Identifier:
22490959
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COLLISIONLESS PLASMA; COMPUTERIZED SIMULATION; ELECTRON-ION COLLISIONS; ELECTRONS; LANGMUIR FREQUENCY; MACH NUMBER; MAGNETIC FIELDS; SHEAR; STABILITY; THERMAL DIFFUSION; TWO-DIMENSIONAL CALCULATIONS; VARIATIONS