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

Abstract

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
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
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

Citation Formats

Hirota, M., Hattori, Y., and Morrison, P. J. Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma. United States: N. p., 2015. Web. doi:10.1063/1.4921329.
Hirota, M., Hattori, Y., & Morrison, P. J. Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma. United States. doi:10.1063/1.4921329.
Hirota, M., Hattori, Y., and Morrison, P. J. Fri . "Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma". United States. doi:10.1063/1.4921329.
@article{osti_22410294,
title = {Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma},
author = {Hirota, M. and Hattori, Y. and Morrison, P. J.},
abstractNote = {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 of the explosive growth rate agrees well with the simulation results.},
doi = {10.1063/1.4921329},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 22,
place = {United States},
year = {2015},
month = {5}
}