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Title: Dynamics of double layers, ion acceleration, and heat flux suppression during solar flares

Abstract

Observations of flare-heated electrons in the corona typically suggest confinement of electrons. The confinement mechanism, however, remains unclear. The transport of coronal hot electrons into ambient plasma was recently investigated by particle-in-cell (PIC) simulations. Electron transport was significantly suppressed by the formation of a highly localized, nonlinear electrostatic potential in the form of a double layer (DL). In this work large-scale PIC simulations are performed to explore the dynamics of DLs in larger systems where, instead of a single DL, multiple DLs are generated. The primary DL accelerates return current electrons, resulting in high velocity electron beams that interact with ambient ions. This forms a Buneman unstable system that spawns more DLs. Trapping of heated return current electrons between multiple DLs strongly suppresses electron transport. DLs also accelerate ambient ions and produce strong ion flows over an extended region. This clarifies the mechanism by which hot electrons in the corona couple to and accelerate ions to form the solar wind. These new dynamics in larger systems reveal a more likely picture of DL development and their impact on the ambient plasma in the solar corona. They are applicable to the preparation for in situ coronal space missions like the Solarmore » Probe Plus.« less

Authors:
 [1]; ;  [2]
  1. Current address: Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA. (United States)
  2. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States)
Publication Date:
OSTI Identifier:
22365069
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CONFINEMENT; ELECTRON BEAMS; ELECTRONS; HEAT FLUX; INHIBITION; IONS; NONLINEAR PROBLEMS; PLASMA; SIMULATION; SOLAR CORONA; SOLAR FLARES; SOLAR WIND; SPACE; SUN; TRAPPING; VELOCITY

Citation Formats

Li, T. C., Drake, J. F., and Swisdak, M., E-mail: takchu-li@uiowa.edu. Dynamics of double layers, ion acceleration, and heat flux suppression during solar flares. United States: N. p., 2014. Web. doi:10.1088/0004-637X/793/1/7.
Li, T. C., Drake, J. F., & Swisdak, M., E-mail: takchu-li@uiowa.edu. Dynamics of double layers, ion acceleration, and heat flux suppression during solar flares. United States. doi:10.1088/0004-637X/793/1/7.
Li, T. C., Drake, J. F., and Swisdak, M., E-mail: takchu-li@uiowa.edu. Sat . "Dynamics of double layers, ion acceleration, and heat flux suppression during solar flares". United States. doi:10.1088/0004-637X/793/1/7.
@article{osti_22365069,
title = {Dynamics of double layers, ion acceleration, and heat flux suppression during solar flares},
author = {Li, T. C. and Drake, J. F. and Swisdak, M., E-mail: takchu-li@uiowa.edu},
abstractNote = {Observations of flare-heated electrons in the corona typically suggest confinement of electrons. The confinement mechanism, however, remains unclear. The transport of coronal hot electrons into ambient plasma was recently investigated by particle-in-cell (PIC) simulations. Electron transport was significantly suppressed by the formation of a highly localized, nonlinear electrostatic potential in the form of a double layer (DL). In this work large-scale PIC simulations are performed to explore the dynamics of DLs in larger systems where, instead of a single DL, multiple DLs are generated. The primary DL accelerates return current electrons, resulting in high velocity electron beams that interact with ambient ions. This forms a Buneman unstable system that spawns more DLs. Trapping of heated return current electrons between multiple DLs strongly suppresses electron transport. DLs also accelerate ambient ions and produce strong ion flows over an extended region. This clarifies the mechanism by which hot electrons in the corona couple to and accelerate ions to form the solar wind. These new dynamics in larger systems reveal a more likely picture of DL development and their impact on the ambient plasma in the solar corona. They are applicable to the preparation for in situ coronal space missions like the Solar Probe Plus.},
doi = {10.1088/0004-637X/793/1/7},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 793,
place = {United States},
year = {2014},
month = {9}
}