Title: The Effect of a Guide Field on Local Energy Conversion During Asymmetric Magnetic Reconnection: Particle-in-Cell Simulations

Abstract

We use theory and simulations to study how the out-of-plane (guide) magnetic field strength modifies the location where the energy conversion rate between the electric field and the plasma is appreciable during asymmetric magnetic reconnection, motivated by observations (Genestreti et al., 2017). For weak guide fields, energy conversion is maximum on the magnetospheric side of the X line, midway between the X line and electron stagnation point. As the guide field increases, the electron stagnation point gets closer to the X line, and energy conversion occurs closer to the electron stagnation point. We motivate one possible nonrigorous approach to extend the theory of the stagnation point location to include a guidefield. The predictions are compared to two-dimensional particle-in-cell (PIC) simulations with vastly different guide fields. The simulations have upstream parameters corresponding to three events observed with Magnetospheric Multiscale (MMS). The predictions agree reasonably well with the simulation results,capturing trends with the guide field. The theory correctly predicts that the X line and stagnation points approach each other as the guide field increases. The results are compared to MMS observations, Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) observations of each event,and a global resistive-magnetohydrodynamics simulation of the 16 October 2015more » event. The PIC simulation results agree well with the global observations and simulation but differ in the strong electric fields and energy conversion rates found in MMS observations. The observational, theoretical, and numerical resultssuggest that the strong electric fields observed by MMS do not represent a steady global reconnection rate.« less

Authors:

Cassak, P. A.  ^[1];

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Genestreti, K. J. ^[2]; Burch, J. L.  ^[3];

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Phan, T. -D.  ^[4];

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Shay, M. A.  ^[5];

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Swisdak, M.  ^[6];

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Drake, J. F.  ^[6];

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Price, L.  ^[6];

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Eriksson, S.  ^[7];

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Ergun, R. E.  ^[8];

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Anderson, B. J.  ^[9];

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Merkin, V. G.  ^[9];

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Komar, C. M.  ^[10]

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+ Show Author Affiliations

1. West Virginia Univ., Morgantown, WV (United States). Dept. of Physics and Astronomy
2. Austrian Academy of Sciences, Graz (Austria). Space Research Inst.
3. Southwest Research Inst. (SwRI), San Antonio, TX (United States)
4. Univ. of California, Berkeley, CA (United States). Space Sciences Lab.
5. Univ. of Delaware, Newark, DE (United States). Dept. of Physics and Astronomy, and Bartol Research Inst.
6. Univ. of Maryland, College Park, MD (United States)
7. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics
8. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics; Univ. of Colorado, Boulder, CO (United States). Dept. of Astrophysical and Planetary Sciences
9. Johns Hopkins Univ., Baltimore, MD (United States). Applied Physics Lab.
10. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); The Catholic Univ. of America, Washington, DC (United States). Dept. of Physics

Publication Date:

2017-10-31

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1461532

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Volume: 122; Journal Issue: 11; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS