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Title: Plasma Energization in Colliding Magnetic Flux Ropes

Abstract

Magnetic flux ropes are commonly observed throughout the heliosphere, and recent studies suggest that interacting flux ropes are associated with some energetic particle events. In this work, we carry out 2D particle-in-cell (PIC) simulations to study the coalescence of two magnetic flux ropes (or magnetic islands), and the subsequent plasma energization processes. The simulations are initialized with two magnetic islands embedded in a reconnecting current sheet. The two islands collide and eventually merge into a single island. Particles are accelerated during this process as the magnetic energy is released and converted to the plasma energy, including bulk kinetic energy increase by the ideal electric field, and thermal energy increase by the fluid compression and the nonideal electric field. We find that contributions from these different energization mechanisms are all important and comparable with each other. Fluid shear and a nongyrotropic pressure tensor also contribute to the energy conversion process. For simulations with different box sizes ranging from $$L_x$$ ~ 25–100$$d_i$$ and ion-to-electron mass ratios $$m_i /m_e$$ = 25,100, and 400, we find that the general evolution is qualitatively the same for all runs, and the energization depends only weakly on either the system size or the mass ratio. The results may help us understand plasma energization in solar and heliospheric environments.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [4]
  1. Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science; New Mexico Consortium, Los Alamos, NM (United States)
  2. New Mexico Consortium, Los Alamos, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science, and Center for Space Plasma and Aeronomic Research (CSPAR)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States); Nmc, Inc.
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1544070
Grant/Contract Number:  
AC02-05CH11231; SC0018240
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 867; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics

Citation Formats

Du, Senbei, Guo, Fan, Zank, Gary P., Li, Xiaocan, and Stanier, Adam. Plasma Energization in Colliding Magnetic Flux Ropes. United States: N. p., 2018. Web. doi:10.3847/1538-4357/aae30e.
Du, Senbei, Guo, Fan, Zank, Gary P., Li, Xiaocan, & Stanier, Adam. Plasma Energization in Colliding Magnetic Flux Ropes. United States. doi:10.3847/1538-4357/aae30e.
Du, Senbei, Guo, Fan, Zank, Gary P., Li, Xiaocan, and Stanier, Adam. Thu . "Plasma Energization in Colliding Magnetic Flux Ropes". United States. doi:10.3847/1538-4357/aae30e. https://www.osti.gov/servlets/purl/1544070.
@article{osti_1544070,
title = {Plasma Energization in Colliding Magnetic Flux Ropes},
author = {Du, Senbei and Guo, Fan and Zank, Gary P. and Li, Xiaocan and Stanier, Adam},
abstractNote = {Magnetic flux ropes are commonly observed throughout the heliosphere, and recent studies suggest that interacting flux ropes are associated with some energetic particle events. In this work, we carry out 2D particle-in-cell (PIC) simulations to study the coalescence of two magnetic flux ropes (or magnetic islands), and the subsequent plasma energization processes. The simulations are initialized with two magnetic islands embedded in a reconnecting current sheet. The two islands collide and eventually merge into a single island. Particles are accelerated during this process as the magnetic energy is released and converted to the plasma energy, including bulk kinetic energy increase by the ideal electric field, and thermal energy increase by the fluid compression and the nonideal electric field. We find that contributions from these different energization mechanisms are all important and comparable with each other. Fluid shear and a nongyrotropic pressure tensor also contribute to the energy conversion process. For simulations with different box sizes ranging from $L_x$ ~ 25–100$d_i$ and ion-to-electron mass ratios $m_i /m_e$ = 25,100, and 400, we find that the general evolution is qualitatively the same for all runs, and the energization depends only weakly on either the system size or the mass ratio. The results may help us understand plasma energization in solar and heliospheric environments.},
doi = {10.3847/1538-4357/aae30e},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 867,
place = {United States},
year = {2018},
month = {10}
}

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