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  • Accepted Manuscript: Nonthermally dominated electron acceleration during magnetic reconnection in a low- β plasma

Title: Nonthermally dominated electron acceleration during magnetic reconnection in a low- β plasma

By means of fully kinetic simulations, we investigate electron acceleration during magnetic reconnection in a nonrelativistic proton–electron plasma with conditions similar to solar corona and flares. We demonstrate that reconnection leads to a nonthermally dominated electron acceleration with a power-law energy distribution in the nonrelativistic low-β regime but not in the high-β regime, where β is the ratio of the plasma thermal pressure and the magnetic pressure. The accelerated electrons contain most of the dissipated magnetic energy in the low-β regime. A guiding-center current description is used to reveal the role of electron drift motions during the bulk nonthermal energization. We find that the main acceleration mechanism is a Fermi-type acceleration accomplished by the particle curvature drift motion along the electric field induced by the reconnection outflows. Although the acceleration mechanism is similar for different plasma β, low-β reconnection drives fast acceleration on Alfvénic timescales and develops power laws out of thermal distribution. Thus, the nonthermally dominated acceleration resulting from magnetic reconnection in low-β plasma may have strong implications for the highly efficient electron acceleration in solar flares and other astrophysical systems.
Authors:
 [1] ;  [2] ;  [2] ;  [1]
+ Show Author Affiliations
  1. Univ. of Alabama in Huntsville, Huntsville, AL (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-15-23232
Journal ID: ISSN 2041-8213
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 811; Journal Issue: 2; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; acceleration of particles; magnetic reconnection; sun flares; sun corona
OSTI Identifier:
1227724
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