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Title: Particle-in-cell simulations of particle energization from low Mach number fast mode shocks

Abstract

Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation of the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfven Mach number M{sub A}=6.8 and ratio of thermal to magnetic pressure {beta}=8. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulencemore » that sustains the shock.« less

Authors:
;  [1];  [2];  [1];  [2];  [1];  [2];  [2];  [1]
  1. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22072478
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 6; Other Information: (c) 2012 American Institute of Physics; 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; ALFVEN WAVES; ASTROPHYSICS; CALCULATION METHODS; COLLISIONLESS PLASMA; ELECTRON DRIFT; ELECTRONS; IONS; MACH NUMBER; MAGNETIC RECONNECTION; PLASMA SIMULATION; SHOCK WAVES; SOLAR FLARES; TURBULENCE; TWO-DIMENSIONAL CALCULATIONS; TWO-STREAM INSTABILITY

Citation Formats

Park, Jaehong, Blackman, Eric G., Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Workman, Jared C., Department of Physical and Environmental Sciences, Colorado Mesa University, Grand Junction, Colorado 81501, Ren, Chuang, Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627, and Siller, Robert. Particle-in-cell simulations of particle energization from low Mach number fast mode shocks. United States: N. p., 2012. Web. doi:10.1063/1.4729913.
Park, Jaehong, Blackman, Eric G., Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Workman, Jared C., Department of Physical and Environmental Sciences, Colorado Mesa University, Grand Junction, Colorado 81501, Ren, Chuang, Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627, & Siller, Robert. Particle-in-cell simulations of particle energization from low Mach number fast mode shocks. United States. doi:10.1063/1.4729913.
Park, Jaehong, Blackman, Eric G., Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Workman, Jared C., Department of Physical and Environmental Sciences, Colorado Mesa University, Grand Junction, Colorado 81501, Ren, Chuang, Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627, and Siller, Robert. Fri . "Particle-in-cell simulations of particle energization from low Mach number fast mode shocks". United States. doi:10.1063/1.4729913.
@article{osti_22072478,
title = {Particle-in-cell simulations of particle energization from low Mach number fast mode shocks},
author = {Park, Jaehong and Blackman, Eric G. and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 and Workman, Jared C. and Department of Physical and Environmental Sciences, Colorado Mesa University, Grand Junction, Colorado 81501 and Ren, Chuang and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 and Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 and Siller, Robert},
abstractNote = {Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation of the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfven Mach number M{sub A}=6.8 and ratio of thermal to magnetic pressure {beta}=8. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock.},
doi = {10.1063/1.4729913},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 6,
volume = 19,
place = {United States},
year = {2012},
month = {6}
}