Kinetic Dissipation Around a Dipolarization Front

Sitnov, M. I.; Merkin, V. G.; Roytershteyn, V.; Swisdak, M.

doi:10.1029/2018gl077874

Cited by 50 publications

(55 citation statements)

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“…We used the same technique as Dunlop et al (2002) to calculate the spatial velocity gradients in Pi − D. Pi − D (i) and Pi − D (e) show small perturbation at the DF, while they exhibit large perturbation in the FPR, which were probably ascribed to the large ion and electron temperature anisotropies (Figures 1d and 1e). These features are different from those reported in Sitnov et al (2018), which demonstrates that both Pi − D (i) and Pi − D (e) reach positive peaks at DF.…”

Section: Figures 1j and 1kcontrasting

confidence: 99%

“…Our observations of 122 DFs probably sample these DFs at different Y locations, thus the average values shown in Figure are similar to the values averaged in Y in simulations (e.g., Lapenta et al, ). Recent three‐dimensional PIC simulations demonstrate that ripples developed on the DF cause the coexistence of the load (J · E > 0) and generator (J · E < 0) regions on the same DF (e.g., Lapenta et al, ; Pritchett, ; Sitnov et al, , ). The scale size of these ripples is on the order of the ion inertial length, which is significantly larger than MMS spacing (a few electron inertial length) in our events.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…It should be noted that J · (E+v i × B) = J · (E+v e × B) when assuming charge neutrality (n i = n e ). Thus, it cannot be used to distinguish the dissipation between electrons and ions (Sitnov et al, ; Yao et al, ). In MHD theory, it describes the change of local entropy (Birn & Hesse, ).…”

Section: Introductionmentioning

confidence: 99%

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Energy Conversion and Dissipation at Dipolarization Fronts: A Statistical Overview

Zhong

Deng

Zhou

et al. 2019

Geophysical Research Letters

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Dipolarization fronts (DFs) are important for energy conversion, particle acceleration, and flux transport in the magnetotail. The partition of energy conversion between ions and electrons and the energy dissipation at DFs are not well understood. In this paper, we present a statistical study of energy conversion and dissipation of 122 DFs observed by Magnetospheric Multiscale mission in the magnetotail. Statistically, electromagnetic energy transfers to plasma at DF. The released energy is mainly transferred to ions rather than electrons. On average, ions gain energy across the whole DF, while electrons gain energy at the leading part but lose energy at the trailing part of DFs. Joule dissipation J · (E+ve × B) can be either positive or negative at DFs, and its average value is very small. The kinetic energy dissipation parameter Pi − D does not exhibit clear signatures at the DFs; hence, it is not suitable for quantifying the energy dissipation at DF.

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Section: Figures 1j and 1kcontrasting

confidence: 99%

Section: Discussion and Summarymentioning

confidence: 99%

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Energy Conversion and Dissipation at Dipolarization Fronts: A Statistical Overview

Zhong

Deng

Zhou

et al. 2019

Geophysical Research Letters

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“…This idea can be traced back to early works by Braginskii [63], which is generalized into the kinetic realm of collisionless systems by Del Sarto et al [64,65] as well. More recently, there is growing evidence that elucidates the role of pressure-strain interaction using numerical simulations [66] and observations [67].…”

Section: Introductionmentioning

confidence: 99%

Scale dependence of energy transfer in turbulent plasma

Yang

Wan

Matthaeus

et al. 2018

Monthly Notices of the Royal Astronomical Society

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In the context of space and astrophysical plasma turbulence and particle heating, several vocabularies emerge for estimating turbulent energy dissipation rate, including Kolmogorov-Yaglom third-order law and, in its various forms, j ·E (work done by the electromagnetic field on particles), and − (P · ∇) · u (pressure-strain interaction), to name a couple. It is now understood that these energy transfer channels, to some extent, are correlated with coherent structures. In particular, we find that different energy dissipation proxies, although not point-wise correlated, are concentrated in proximity to each other, for which they decorrelate in a few d i (s). However, the energy dissipation proxies dominate at different scales. For example, there is an inertial range over which the third-order law is meaningful. Contributions from scale bands stemming from scale-dependent spatial filtering show that, the energy exchange through j · E mainly results from large scales, while the energy conversion from fluid flow to internal through − (P · ∇) · u dominates at small scales. * wanmp@sustc.edu.cn arXiv:1809.05677v1 [physics.space-ph]

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“…Fu, Khotyaintsev, Vaivads, André, & Huang, ; Khotyaintsev et al, ; Schmid et al, ; Lu et al, ), earlier studies concluded that on subgyroscales, the DFs might be complex with embedded small scale dissipative layers (e.g. Angelopoulos et al, ; Balikhin et al, ; Sitnov et al, ) and that DFs cannot be described completely by the MHD theory and show a more diverse picture on small scales.…”

Section: Introductionmentioning

confidence: 99%

Dipolarization Fronts: Tangential Discontinuities? On the Spatial Range of Validity of the MHD Jump Conditions

et al. 2019

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Magnetotail dipolarization fronts (DFs) are referred as the sharp increase of the northward magnetic field component, embedded in bursts of fast earthward moving plasma flows, so called bursty bulk flows. Earlier studies often considered DFs as tangential discontinuities (TDs), which can be understood as thin vertical current layers of earthward moving flux tubes, so called dipolarzing flux bundles (DFBs), which separate the ambient plasma sheet plasma from the low entropy plasma within the DFB. Here we present a statistical study of 23 DFs observed by the Magnetospheric Multiscale mission during 2017 and 2018 when the apogee was at 25 R E in the magnetotail. We perform a test of the Walén relation to distinguish whether the observed DFs have rather a TD or rotational discontinuity character and evaluate the plasma flow across the DFs in detail. The results show that on MHD large scales, all 23 DFs can be considered as TD like, but sometimes may have a significant normal plasma flow across it: for 16 events (∼ 70%), the plasma flows mainly tangential to the DFs, while for seven events (∼ 30%), the plasma flows mainly across the DFs. Based on the findings present in this study, we further hypothesize that the DF structure becomes more distorted and unstable in a (locally) more dipolarized background magnetic field region, which may additionally facilitate the plasma flow across the front.sides of this type of discontinuity. For RDs, on the other hand, all field and plasma quantities are continuous across it and only a rotation of the tangential velocity and magnetic field vectors within the discontinuity take place. This implies that for RDs, a change of the plasma velocity and the Alfvén velocity across the discontinuity must change accordingly. This relation is called the Walén relation (e.g. Hudson, 1970) and is valid for linear and nonlinear Alfvén waves (RDs are nonlinear Alfvénic waves). Note that the alignment between the plasma and Alfvén velocity alone is not sufficient to discriminate TDs from RDs, since such an alignment would be also present, for example, for Alfvénic surface waves traveling along a TDs Denskat and Burlaga (1977). The ratio of the magnitude changes of plasma and Alfvén velocity, however, may be a distinctive feature. Previous studies often used this Walén relation as a criteria to distinguish RDs and TDs in the solar wind (e.g. Neugebauer et al., 1984) or at the magnetopause (e.g. Paschmann et al., 1986).

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Kinetic Dissipation Around a Dipolarization Front

Cited by 50 publications

References 53 publications

Energy Conversion and Dissipation at Dipolarization Fronts: A Statistical Overview

Energy Conversion and Dissipation at Dipolarization Fronts: A Statistical Overview

Scale dependence of energy transfer in turbulent plasma

Dipolarization Fronts: Tangential Discontinuities? On the Spatial Range of Validity of the MHD Jump Conditions

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