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Title: Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations

An electron diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale spacecraft at the Earth's magnetopause. The distinct substructures in the EDR on both sides of the reconnecting current sheet are visualized with electron distribution functions that are 2 orders of magnitude higher cadence than ever achieved to enable the following new findings: (1) Motion of the demagnetized electrons plays an important role to sustain the reconnection current and contributes to the dissipation due to the nonideal electric field, (2) the finite guide field dominates over the Hall magnetic field in an electron–scale region in the exhaust and modifies the electron flow dynamics in the EDR, (3) the reconnection current is in part carried by inflowing field–aligned electrons in the magnetosphere part of the EDR, and (4) the reconnection electric field measured by multiple spacecraft is uniform over at least eight electron skin depths and corresponds to a reconnection rate of approximately 0.1. Here, the observations establish the first look at the structure of the EDR under a weak but not negligible guide field.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [1] ; ORCiD logo [5] ; ORCiD logo [2] ;  [6] ; ORCiD logo [7] ;  [2] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [8] ; ORCiD logo [9] ; ORCiD logo [9] ; ORCiD logo [10] ; ORCiD logo [11] ; ORCiD logo [1]
  1. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  2. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  3. Univ. of Colorado, Boulder, CO (United States)
  4. Southwest Research Institute, San Antonio, TX (United States)
  5. Southwest Research Institute, San Antonio, TX (United States); Univ. of New Hampshire, Durham, NH (United States)
  6. Rice Univ., Houston, TX (United States)
  7. Denali Scientific, Healy, AK (United States)
  8. Univ. de Toulouse, Toulouse (France); Centre National de la Recherche Scientifique, Toulouse (France)
  9. Univ. of California, Los Angeles, CA (United States)
  10. Swedish Institute of Space Physics, Uppsala (Sweden)
  11. KTH Royal Institute of Technology, Stockholm (Sweden)
Publication Date:
Grant/Contract Number:
SC0016278; DESC0016278
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 5; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Research Org:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; magnetic reconnection; diffusion region; electron acceleration; electric field acceleration; electron diffusion region
OSTI Identifier:
1466266
Alternate Identifier(s):
OSTI ID: 1402346

Chen, L. -J., Hesse, M., Wang, S., Gershman, D., Ergun, R. E., Burch, J., Bessho, N., Torbert, R. B., Giles, B., Webster, J., Pollock, C., Dorelli, J., Moore, T., Paterson, W., Lavraud, B., Strangeway, R., Russell, C., Khotyaintsev, Y., Lindqvist, P. -A., and Avanov, L.. Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations. United States: N. p., Web. doi:10.1002/2017JA024004.
Chen, L. -J., Hesse, M., Wang, S., Gershman, D., Ergun, R. E., Burch, J., Bessho, N., Torbert, R. B., Giles, B., Webster, J., Pollock, C., Dorelli, J., Moore, T., Paterson, W., Lavraud, B., Strangeway, R., Russell, C., Khotyaintsev, Y., Lindqvist, P. -A., & Avanov, L.. Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations. United States. doi:10.1002/2017JA024004.
Chen, L. -J., Hesse, M., Wang, S., Gershman, D., Ergun, R. E., Burch, J., Bessho, N., Torbert, R. B., Giles, B., Webster, J., Pollock, C., Dorelli, J., Moore, T., Paterson, W., Lavraud, B., Strangeway, R., Russell, C., Khotyaintsev, Y., Lindqvist, P. -A., and Avanov, L.. 2017. "Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations". United States. doi:10.1002/2017JA024004. https://www.osti.gov/servlets/purl/1466266.
@article{osti_1466266,
title = {Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations},
author = {Chen, L. -J. and Hesse, M. and Wang, S. and Gershman, D. and Ergun, R. E. and Burch, J. and Bessho, N. and Torbert, R. B. and Giles, B. and Webster, J. and Pollock, C. and Dorelli, J. and Moore, T. and Paterson, W. and Lavraud, B. and Strangeway, R. and Russell, C. and Khotyaintsev, Y. and Lindqvist, P. -A. and Avanov, L.},
abstractNote = {An electron diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale spacecraft at the Earth's magnetopause. The distinct substructures in the EDR on both sides of the reconnecting current sheet are visualized with electron distribution functions that are 2 orders of magnitude higher cadence than ever achieved to enable the following new findings: (1) Motion of the demagnetized electrons plays an important role to sustain the reconnection current and contributes to the dissipation due to the nonideal electric field, (2) the finite guide field dominates over the Hall magnetic field in an electron–scale region in the exhaust and modifies the electron flow dynamics in the EDR, (3) the reconnection current is in part carried by inflowing field–aligned electrons in the magnetosphere part of the EDR, and (4) the reconnection electric field measured by multiple spacecraft is uniform over at least eight electron skin depths and corresponds to a reconnection rate of approximately 0.1. Here, the observations establish the first look at the structure of the EDR under a weak but not negligible guide field.},
doi = {10.1002/2017JA024004},
journal = {Journal of Geophysical Research. Space Physics},
number = 5,
volume = 122,
place = {United States},
year = {2017},
month = {4}
}