Electromagnetic energy conversion at dipolarization fronts: Multispacecraft results

Huang, Suming; Fu, Huishan; Yuan, Zhiyong; Zhou, Meng; Fu, Song; Deng, Xiaohua; Sun, W.; Pang, Y.; Wang, D. D.; Li, H. M.; Yu, Xiongdong

doi:10.1002/2015ja021083

Cited by 92 publications

(128 citation statements)

References 44 publications

(95 reference statements)

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“…The loads show a peak value approaching 150 pW/m 3 , which is~3 times larger than the typical value (e.g., Huang et al, 2015) but still much smaller than the value (up to 6,000 pW/m 3 ) reported by Angelopoulos et al (2013). The loads show a peak value approaching 150 pW/m 3 , which is~3 times larger than the typical value (e.g., Huang et al, 2015) but still much smaller than the value (up to 6,000 pW/m 3 ) reported by Angelopoulos et al (2013).…”

Section: Summary and Discussionmentioning

confidence: 70%

Electron‐Scale Measurements of Dipolarization Front

Liu

et al. 2018

Geophysical Research Letters

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Dipolarization front (DF)—a sharp boundary with scale of ion inertial length (c/ωpi) in the Earth's magnetotail—can also have fine structures at electron scale (c/ωpe). Such electron‐scale structures, determining the local energy conversion, have not been revealed by multispacecraft observations so far, due to the large separation of spacecraft in previous studies. Here we report the first electron‐scale multispacecraft measurements of DF, using data from the recent Magnetospheric Multiscale mission. We find strong parallel currents only in the high‐density side of the DF but strong perpendicular currents across the whole DF. We find no parallel electric fields during the DF interval. Although DF is primarily an energy‐load region (E·J > 0), the electron‐scale currents could lead to a localized energy generation (E·J < 0). Such features are different from those reported in previous multispacecraft studies, where the currents, electric fields, and energy conversion are uniform across the DF; they also shed lights on the study of substorm current wedge, which is crucial in the magnetosphere‐ionosphere coupling.

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Section: Summary and Discussionmentioning

confidence: 70%

Electron‐Scale Measurements of Dipolarization Front

Liu

et al. 2018

Geophysical Research Letters

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“…The new experimental capabilities provided by MMS and discussed above allow us to address the fundamental question about the role of DFs in energy conversion in the magnetotail. Previous studies have reported that energy is transferred from field to plasma (i.e., J · E >0) on the DF [ Hamrin et al , ; Huang et al , ]. However, the accuracy of J · E strongly depends on the current density calculation and 3‐D electric field measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Clearly, J · E is positive, with a peak power of ∼250 pW/m 3 . The positive value is consistent with previous energy conversion on the DF with J · E [e.g., Huang et al , ]. J ·( E + V e × B ) and J ·( E + V i × B ) are both negative, with a peak power of ∼−80 pW/m 3 .…”

Section: Discussionmentioning

confidence: 99%

A direct examination of the dynamics of dipolarization fronts using MMS

Yao¹,

Rae²,

Guo

et al. 2017

JGR Space Physics

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Energy conversion on the dipolarization fronts (DFs) has attracted much research attention through the suggestion that intense current densities associated with DFs can modify the more global magnetotail current system. The current structures associated with a DF are at the scale of one to a few ion gyroradii, and their duration is comparable to a spacecraft's spin period. Hence, it is crucial to understand the physical mechanisms of DFs with measurements at a timescale shorter than a spin period. We present a case study whereby we use measurements from the Magnetospheric Multiscale (MMS) Mission, which provides full 3‐D particle distributions with a cadence much shorter than a spin period. We provide a cross validation amongst the current density calculations and examine the assumptions that have been adopted in previous literature using the advantages of MMS mission (i.e., small‐scale tetrahedron and high temporal resolution). We also provide a cross validation on the terms in the generalized Ohm's law using these advantageous measurements. Our results clearly show that the majority of the currents on the DF are contributed by both ion and electron diamagnetic drifts. Our analysis also implies that the ion frozen‐in condition does not hold on the DF, while electron frozen‐in condition likely holds. The new experimental capabilities allow us to accurately calculate Joule heating within the DF, which shows that plasma energy is being converted to magnetic energy in our event.

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“…This gives in situ evidence that transient reconnection can produce DFs [ Fu et al, ]. DFs, also called jet fronts, are characterized by the sharp increase of magnetic field | B z | component (GSM coordinates) embedded inside the high‐speed plasma flows in the magnetotail [e.g., Nakamura et al , ; Runov et al , ; Sitnov et al , ; Fu et al , , , ; Huang et al , , ]. In this event, the Cluster separation was about 3000 km (Figure a).…”

Section: Observationsmentioning

confidence: 97%

Two types of whistler waves in the hall reconnection region

Huang

Yuan

et al. 2016

JGR Space Physics

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Whistler waves are believed to play an important role during magnetic reconnection. Here we report the near‐simultaneous occurrence of two types of the whistler‐mode waves in the magnetotail Hall reconnection region. The first type is observed in the magnetic pileup region of downstream and propagates away to downstream along the field lines and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type, propagating toward the X line, is found around the separatrix region and probably is generated by the electron beam‐driven whistler instability or Čerenkov emission from electron phase‐space holes. These observations of two different types of whistler waves are consistent with recent kinetic simulations and suggest that the observed whistler waves are a consequence of magnetic reconnection.

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Electromagnetic energy conversion at dipolarization fronts: Multispacecraft results

Cited by 92 publications

References 44 publications

Electron‐Scale Measurements of Dipolarization Front

Electron‐Scale Measurements of Dipolarization Front

A direct examination of the dynamics of dipolarization fronts using MMS

Two types of whistler waves in the hall reconnection region

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