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

Abstract

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]
  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:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1227724
Report Number(s):
LA-UR-15-23232
Journal ID: ISSN 2041-8213
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: 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)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; acceleration of particles; magnetic reconnection; sun flares; sun corona

Citation Formats

Li, Xiaocan, Guo, Fan, Li, Hui, and Li, Gang. Nonthermally dominated electron acceleration during magnetic reconnection in a low-β plasma. United States: N. p., 2015. Web. doi:10.1088/2041-8205/811/2/L24.
Li, Xiaocan, Guo, Fan, Li, Hui, & Li, Gang. Nonthermally dominated electron acceleration during magnetic reconnection in a low-β plasma. United States. doi:10.1088/2041-8205/811/2/L24.
Li, Xiaocan, Guo, Fan, Li, Hui, and Li, Gang. Thu . "Nonthermally dominated electron acceleration during magnetic reconnection in a low-β plasma". United States. doi:10.1088/2041-8205/811/2/L24. https://www.osti.gov/servlets/purl/1227724.
@article{osti_1227724,
title = {Nonthermally dominated electron acceleration during magnetic reconnection in a low-β plasma},
author = {Li, Xiaocan and Guo, Fan and Li, Hui and Li, Gang},
abstractNote = {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.},
doi = {10.1088/2041-8205/811/2/L24},
journal = {The Astrophysical Journal. Letters},
issn = {2041-8213},
number = 2,
volume = 811,
place = {United States},
year = {2015},
month = {9}
}

Journal Article:
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Cited by: 24 works
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