Electron dynamics in a subproton‐gyroscale magnetic hole

Gershman, D. J.; Dorelli, J.; Viñas, A. F.; Avanov, L. A.; Gliese, U.; Barrie, A. C.; Coffey, V. N.; Chandler, M. O.; Dickson, C. R.; MacDonald, E.; Salo, C.; Holland, Matthew; Saito, Y.; Sauvaud, J. A.; Lavraud, B.; Paterson, W. R.; Torbert, R. B.; Chen, Li‐Jen; Goodrich, K.; Russell, C. T.; Strangeway, R. J.; Giles, B. L.; Pollock, C. J.; Moore, T. E.; Burch, J. L.

doi:10.1002/2016gl068545

Cited by 58 publications

(82 citation statements)

References 25 publications

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“…Taking MH geometry (as shown by Figure ) into account, we use plasma flows along the x axis to estimate the current density. The electron bulk velocity, v ex , obtained from direct ESA measurements significantly exceeds the ion bulk velocity ( v ex reaches 400 km/s, comparable with previous observations [ Gershman et al , ]). Electrons flow in opposite directions at two hole boundaries, generating current density j ex =− e n e v ex that supports the magnetic field gradients.…”

Section: Magnetic Hole Kineticssupporting

confidence: 89%

“…Thus, we can assume that these cold (at energies <1 keV) electrons do not contribute to MH structure. Similar conclusions, but for energies <0.2 keV, were drawn by Gershman et al [].…”

Section: Magnetic Hole Kineticssupporting

confidence: 88%

“…Gershman et al [] and Yao et al [] showed that electron distributions within MHs exhibit significant anisotropies with increased transverse fluxes in the 0.2–4 keV energy range. We checked that the electron population below 500 eV does not contribute to the observed electron bulk velocity v ex , and thus only suprathermal particles are responsible for current generation.…”

Section: Magnetic Hole Kineticsmentioning

confidence: 99%

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Kinetics of sub‐ion scale magnetic holes in the near‐Earth plasma sheet

et al. 2017

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In collisionless space plasmas, the energy cascade from larger to smaller scales requires effective interactions between ions and electrons. These interactions are organized by sub‐ion scale plasma structures in which strong electric fields connect demagnetized ions to magnetized electrons. We consider one such structure, magnetic holes, observed by THEMIS spacecraft in the dipolarized hot plasma sheet. Magnetic holes are localized depressions of the magnetic field with strong currents at their boundaries. Taking advantage of slow plasma convection (∼10–20 km/s), we reconstruct the electron velocity distribution within magnetic holes and demonstrate that the current at their boundaries is predominantly carried by magnetized thermal electrons. The motion of these electrons is the combination of diamagnetic drift and E × B drift in a Hall electric field. Magnetic holes can effectively modulate the intensity of electron cyclotron harmonic waves, and thus the spatial distribution of thermal electron precipitation. They may also contain field‐aligned currents with magnitudes of ∼5 nA/m2 (1 order of magnitude smaller than the cross‐field current density). Therefore, sub‐ion scale magnetic holes can be important for ionosphere‐magnetosphere coupling.

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Section: Magnetic Hole Kineticssupporting

confidence: 89%

“…Thus, we can assume that these cold (at energies <1 keV) electrons do not contribute to MH structure. Similar conclusions, but for energies <0.2 keV, were drawn by Gershman et al [].…”

Section: Magnetic Hole Kineticssupporting

confidence: 88%

Section: Magnetic Hole Kineticsmentioning

confidence: 99%

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Kinetics of sub‐ion scale magnetic holes in the near‐Earth plasma sheet

et al. 2017

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“…Subion scale MHs have been observed both in steady and turbulent plasmas (Gershman et al, 2016;Huang, Du, et al, 2017;Yao et al, 2017;Zhang et al, 2017). Subion scale MHs have been observed both in steady and turbulent plasmas (Gershman et al, 2016;Huang, Du, et al, 2017;Yao et al, 2017;Zhang et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…It has been widely observed in various space plasmas, including the solar wind (Turner et al, 1977;Winterhalter et al, 1995;Zhang et al, 2008), the comet magnetosphere (Russell et al, 1987), the planetary magnetosheath (Balikhin et al, 2009;Cattaneo et al, 1998;Huang, Du, et al, 2017;Joy et al, 2006;Lucek et al, 1999;Tsurutani et al, 1982;Violante et al, 1995), and the magnetosphere (Ge et al, 2011;Gershman et al, 2016;Shi et al, 2009;Sun et al, 2012;Zhang et al, 2017). It has been widely observed in various space plasmas, including the solar wind (Turner et al, 1977;Winterhalter et al, 1995;Zhang et al, 2008), the comet magnetosphere (Russell et al, 1987), the planetary magnetosheath (Balikhin et al, 2009;Cattaneo et al, 1998;Huang, Du, et al, 2017;Joy et al, 2006;Lucek et al, 1999;Tsurutani et al, 1982;Violante et al, 1995), and the magnetosphere (Ge et al, 2011;Gershman et al, 2016;Shi et al, 2009;Sun et al, 2012;Zhang et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

Zhong

Zhou

Huang

et al. 2019

Geophysical Research Letters

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Magnetic holes have been widely observed in various space plasma systems. The origin of magnetic holes and their influence to background plasma are under debate. In this paper, we show a kinetic‐scale electron vortex magnetic hole in a nonideal region of an active X line, which was observed by the Magnetospheric Multiscale mission at the dayside magnetopause. Intense current and nonideal electric field in the electron frame were observed within the magnetic hole, which led to a strong energy dissipation. Thus, the electron vortex magnetic hole probably provided an additional energy dissipation channel besides the electron diffusion region adjacent to the hole. We suggest that magnetic reconnection provided favorable conditions for the formation of this kinetic‐scale magnetic hole and is an important source of magnetic holes in space plasma.

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MMS Multipoint electric field observations of small‐scale magnetic holes

Goodrich

Ergun

Wilder

et al. 2016

Geophysical Research Letters

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Small‐scale magnetic holes (MHs), local depletions in magnetic field strength, have been observed multiple times in the Earth's magnetosphere in the bursty bulk flow (BBF) braking region. This particular subset of MHs has observed scale sizes perpendicular to the background magnetic field (B) less than the ambient ion Larmor radius (ρi). Previous observations by Time History of Events and Macroscale Interactions during Substorms (THEMIS) indicate that this subset of MHs can be supported by a current driven by the E × B drift of electrons. Ions do not participate in the E × B drift due to the small‐scale size of the electric field. While in the BBF braking region, during its commissioning phase, the Magnetospheric Multiscale (MMS) spacecraft observed a small‐scale MH. The electric field observations taken during this event suggest the presence of electron currents perpendicular to the magnetic field. These observations also suggest that these currents can evolve to smaller spatial scales.

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Electron dynamics in a subproton‐gyroscale magnetic hole

Cited by 58 publications

References 25 publications

Kinetics of sub‐ion scale magnetic holes in the near‐Earth plasma sheet

Kinetics of sub‐ion scale magnetic holes in the near‐Earth plasma sheet

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

MMS Multipoint electric field observations of small‐scale magnetic holes

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