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Title: Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection

Abstract

We perform the first study of the properties of the Larmor electric field (LEF) in collisionless asymmetric magnetic reconnection in the presence of an out-of-plane (guide) magnetic field for different sets of representative upstream parameters at Earth’s dayside magnetopause with an ion temperature greater than the electron temperature (the ion-to-electron temperature ratio fixed at 2) using two-dimensional particle-in-cell simulations. We show that the LEF does persist in the presence of a guide field. We study how the LEF thickness and strength change as a function of guide field and the magnetospheric temperature and reconnecting magnetic field strength. We find that the thickness of the LEF structure decreases, while its magnitude increases when a guide field is added to the reconnecting magnetic field. The added guide field makes the Larmor radius smaller, so the scaling with the magnetospheric ion Larmor radius is similar to that reported for the case without a guide field. Note, however, that the physics causing the LEF is not well understood, so future work in other parameter regimes is needed to fully predict the LEF for arbitrary conditions. We also find that a previously reported upstream electron temperature anisotropy arises in the vicinity of the LEF regionmore » both with and without a guide field. We argue that the generation of the anisotropy is linked to the existence of the LEF. The LEF can be used in combination with the electron temperature anisotropy as a signature to effectively identify dayside reconnection sites in observations.« less

Authors:
;  [1];  [2];  [3];  [4]
  1. Department of Physics, Faculty of Science, Mahidol University, Bangkok (Thailand)
  2. Department of Physics, Faculty of Science and Techonology, Thammasat University, Pathum Thani (Thailand)
  3. Department of Physics and Astronomy, University of Delaware, Newark, DE (United States)
  4. Department of Physics and Astronomy, West Virginia University, Morgantown, WV (United States)
Publication Date:
OSTI Identifier:
22663236
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 845; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; ASYMMETRY; ELECTRIC FIELDS; ELECTRON TEMPERATURE; ELECTRONS; ION TEMPERATURE; IONS; LARMOR RADIUS; MAGNETIC FIELDS; MAGNETIC RECONNECTION; MAGNETOPAUSE; PLASMA; SIMULATION; THICKNESS; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Ek-In, Surapat, Ruffolo, David, Malakit, Kittipat, Shay, Michael A., and Cassak, Paul A., E-mail: kmalakit@gmail.com. Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7F2C.
Ek-In, Surapat, Ruffolo, David, Malakit, Kittipat, Shay, Michael A., & Cassak, Paul A., E-mail: kmalakit@gmail.com. Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection. United States. doi:10.3847/1538-4357/AA7F2C.
Ek-In, Surapat, Ruffolo, David, Malakit, Kittipat, Shay, Michael A., and Cassak, Paul A., E-mail: kmalakit@gmail.com. Sun . "Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection". United States. doi:10.3847/1538-4357/AA7F2C.
@article{osti_22663236,
title = {Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection},
author = {Ek-In, Surapat and Ruffolo, David and Malakit, Kittipat and Shay, Michael A. and Cassak, Paul A., E-mail: kmalakit@gmail.com},
abstractNote = {We perform the first study of the properties of the Larmor electric field (LEF) in collisionless asymmetric magnetic reconnection in the presence of an out-of-plane (guide) magnetic field for different sets of representative upstream parameters at Earth’s dayside magnetopause with an ion temperature greater than the electron temperature (the ion-to-electron temperature ratio fixed at 2) using two-dimensional particle-in-cell simulations. We show that the LEF does persist in the presence of a guide field. We study how the LEF thickness and strength change as a function of guide field and the magnetospheric temperature and reconnecting magnetic field strength. We find that the thickness of the LEF structure decreases, while its magnitude increases when a guide field is added to the reconnecting magnetic field. The added guide field makes the Larmor radius smaller, so the scaling with the magnetospheric ion Larmor radius is similar to that reported for the case without a guide field. Note, however, that the physics causing the LEF is not well understood, so future work in other parameter regimes is needed to fully predict the LEF for arbitrary conditions. We also find that a previously reported upstream electron temperature anisotropy arises in the vicinity of the LEF region both with and without a guide field. We argue that the generation of the anisotropy is linked to the existence of the LEF. The LEF can be used in combination with the electron temperature anisotropy as a signature to effectively identify dayside reconnection sites in observations.},
doi = {10.3847/1538-4357/AA7F2C},
journal = {Astrophysical Journal},
number = 2,
volume = 845,
place = {United States},
year = {Sun Aug 20 00:00:00 EDT 2017},
month = {Sun Aug 20 00:00:00 EDT 2017}
}