Magnetospheric Multiscale Observations of an Ion Diffusion Region With Large Guide Field at the Magnetopause: Current System, Electron Heating, and Plasma Waves

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JGR Space Physics - 2018 - Zhou - Magnetospheric Multiscale Observations of an Ion Diffusion Region With Large Guide Field.pdf (9.93 MB)

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https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017JA024517

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https://doi.org/10.1002/2017JA024517
 http://hdl.handle.net/11603/31342

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UMBC Goddard Planetary Heliophysics Institute (GPHI)
UMBC Faculty Collection

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Author/Creator ORCID

https://orcid.org/0000-0002-5317-988X

Date

2018-02-20

Type of Work

journal articles
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Citation of Original Publication

Zhou, M., Berchem, J., Walker, R. J., El-Alaoui, M., Goldstein, M. L., Lapenta, G., et al. (2018). Magnetospheric Multiscale observations of an ion diffusion region with large guide field at the magnetopause: Current system, electron heating, and plasma waves. Journal of Geophysical Research: Space Physics, 123, 1834–1852. https://doi.org/10.1002/2017JA024517

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

We report Magnetospheric Multiscale (MMS) observations of a reconnecting current sheet in the presence of a weak density asymmetry with large guide field at the dayside magnetopause. An ion diffusion region (IDR) was detected associated with this current sheet. Parallel current dominated over the perpendicular current in the IDR, as found in previous studies of component reconnection. Electrons were preferentially heated parallel to the magnetic field within the IDR. The heating was manifested as a flattop distribution below 400 eV. Two types of electromagnetic electron whistler waves were observed within the regions where electrons were heated. One type of whistler wave was associated with nonlinear structures in E|| with amplitudes up to 20 mV/m. The other type was not associated with any structures in E||. Poynting fluxes of these two types of whistler waves were directed away from the X-line. We suggest that the nonlinear evolution of the oblique whistler waves gave rise to the solitary structures in E||. There was a perpendicular super-Alfvénic outflow jet that was carried by magnetized electrons. Intense electrostatic lower hybrid drift waves were localized in the current sheet center and were probably driven by the super-Alfvénic electron jet, the velocity of which was approximately equal to the diamagnetic drift of demagnetized ions. Our observations suggest that the guide field significantly modified the structures (Hall electromagnetic fields and current system) and wave properties in the IDR.