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Title: Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma

A mechanism for explosive magnetic reconnection is investigated by analyzing the nonlinear evolution of a collisionless tearing mode in a two-fluid model that includes the effects of electron inertia and temperature. These effects cooperatively enable a fast reconnection by forming an X-shaped current-vortex layer centered at the reconnection point. A high-resolution simulation of this model for an unprecedentedly small electron skin depth d{sub e} and ion-sound gyroradius ρ{sub s}, satisfying d{sub e}=ρ{sub s}, shows an explosive tendency for nonlinear growth of the tearing mode, where it is newly found that the explosive widening of the X-shaped layer occurs locally around the reconnection point with the length of the X shape being shorter than the domain length and the wavelength of the linear tearing mode. The reason for the onset of this locally enhanced reconnection is explained theoretically by developing a novel nonlinear and nonequilibrium inner solution that models the local X-shaped layer, and then matching it to an outer solution that is approximated by a linear tearing eigenmode with a shorter wavelength than the domain length. This theoretical model proves that the local reconnection can release the magnetic energy more efficiently than the global one and the estimated scaling ofmore » the explosive growth rate agrees well with the simulation results.« less
Authors:
;  [1] ;  [2]
  1. Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8677 (Japan)
  2. Department of Physics and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22410294
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 5; 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; ELECTRON TEMPERATURE; ELECTRONS; EXPLOSIVE INSTABILITY; FLOW MODELS; ION ACOUSTIC WAVES; MAGNETIC RECONNECTION; MATHEMATICAL SOLUTIONS; MOMENT OF INERTIA; PLASMA SIMULATION; TEARING INSTABILITY; VORTICES; WAVELENGTHS