Configuration of the Earth’s Magnetotail Current Sheet

Artemyev, А. V.; Lu, San; El‐Alaoui, M.; Lin, Y.; Angelopoulos, V.; Zhang, Xiaojia; Runov, A.; Vasko, I. Y.; Zelenyǐ, L. M.; Russell, C. T.

doi:10.1029/2020gl092153

Cited by 18 publications

(17 citation statements)

References 76 publications

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“…Yet, these current density values shown in Figure 3f are about five times larger than those determined from the large‐scale gradient between Cluster and MMS. This is possible due to the simplified current profile model as well as the large distance (>2 R E ) between Cluster and MMS across the current sheet, which would not allow to model a thin embedded current sheet expected to be observed at growth phase in near‐tail region (Artemyev et al., 2021; Petrukovich et al., 2011, 2015). Furthermore, it is apparent that the local current density in Figure 3f from both Cluster and MMS have a shorter time‐scale enhancement at the beginning of the current sheet thinning.…”

Section: Context Of the Eventmentioning

confidence: 99%

Thin Current Sheet Behind the Dipolarization Front

et al. 2021

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In the near-Earth magnetotail, a major energy conversion process takes place associated with dipolarization and localized fast flows, called bursty bulk flows (BBFs) containing minute-scale flow bursts (FBs; e.g., Angelopoulos et al., 1994;Baumjohann et al., 1989) with a mesoscale (few R E : Earth radii) dawn-dusk size (R. Nakamura et al., 2004) that can ultimately affect the large-scale magnetotail dynamics (Sergeev et al., 2012, and reference therein). These localized BBFs contain sharp enhancements in Bz (south-to-north component of the magnetic field) called dipolarization fronts (DFs;. The thin DF, which has a thickness of 1-3 ion-inertial length and/or gyroradii (Runov et al., 2009;Schmid et al., 2011), is the leading boundary of a dipolarizing flux bundle (DFB; J. Liu et al., 2013), which is a strong magnetic field region, associated with significant Earthward transport of magnetic flux.Azimuthally localized BBFs and DFs have been considered to be associated with the transient/localized reconnection and different interaction processes between a localized fast flow and the ambient plasmas. Evolution of localized reconnection in a 1D Harris type current sheet has been simulated by 3D Hall-MHD simulation (T. K. M. Nakamura et al., 2012;Shay et al., 2003) and 3D PIC simulation (Y.-H. Liu et al., 2019) and the effect of a localized reconnection region on the evolution of the reconnection jets was shown. PIC simulations with normal component of the magnetic field to the initial current sheet, as expected in the near-Earth tail current sheet, reported DF like feature that leads to an onset of new reconnection at its

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Section: Context Of the Eventmentioning

confidence: 99%

Thin Current Sheet Behind the Dipolarization Front

et al. 2021

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“…The associated flow shear ∂u ix / ∂z drives the formation of the ion pressure nongyrotropy, P i , xz , the key element of 1D current sheet models with B z ≠ 0 (see Sitnov & Merkin, 2016; Zelenyi et al., 2011, and references therein). A finite P xz may explain the formation of current sheets with J y exceeding the isotropic limit c ( ∂P xx / ∂x )/ B z (see discussion of such strong J y observations in the magnetotail in Artemyev et al., 2021).…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The second model may be unstable to magnetic reconnection even for an ion‐scale current sheet (Bessho & Bhattacharjee, 2014; Pritchett, 2015; Sitnov et al., 2013). However, both models have difficulties in describing the most intense thin current sheets, those with J y > c ( ∂P / ∂x )/ B z often observed in the magnetotail (Artemyev, Angelopoulos, & Runov, 2016; Artemyev et al., 2021) and even in the reconstructed magnetotail empirical models (see discussion in Sitnov, Stephens, et al., 2021). If the current density J y exceeds c ( ∂P / ∂x )/ B z , the magnetic and thermal stress balance in the magnetotail current sheet requires a contribution from pressure anisotropy (e.g., electron anisotropy, see Artemyev, Vasko, et al., 2016) or nongyrotropy (e.g., P xz ≠ 0 due to ion demagnetized motion around the equatorial plane; see Ashour‐Abdalla et al., 1994; Burkhart et al., 1992; Mingalev et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Configuration of Magnetotail Current Sheet Prior to Magnetic Reconnection Onset

Artemyev

Angelopoulos

et al. 2022

Geophysical Research Letters

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The magnetotail current sheet configuration determines magnetic reconnection properties that control the substorm onset, one of the most energetic phenomena in the Earth’s magnetosphere. The quiet‐time current sheet is often approximated as a two‐dimensional (2D) magnetic field configuration balanced by isotropic plasma pressure gradients. However, reconnection onset is preceded by the current sheet thinning and the formation of a nearly one‐dimensional (1D) magnetic field configuration. In this study, using particle‐in‐cell simulations, we investigate the force balance of such thin current sheets when they are driven by plasma inflow. We demonstrate that the magnetic field configuration transitions from 2D to 1D thanks to the formation of plasma pressure nongyrotropy and reveal its origin in the nongyrotropic terms of the ion distributions. We show that substorm onset may be controlled by the instability and dynamics of such nongyrotropic current sheets, having properties much different from the most commonly investigated 2D isotropic configuration.

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“…In-situ spacecraft measurements of the magnetotail plasma and magnetic field are rather limited, as spacecraft (even multiple) can only simultaneously probe few spatially localized regions (see Refs. 6,7,8,9,10 for examples of probing of the magnetotail current sheet configuration with in-situ multi-spacecraft missions). Thus, alternative methods to examine the current sheet configuration can be especially useful.…”

Section: Introductionmentioning

confidence: 99%

Charged particle scattering in dipolarized magnetotail

Lukin,

Artemyev,

Petrukovich

et al. 2021

Preprint

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The Earth's magnetotail is characterized by stretched magnetic field lines. Energetic particles are effectively scattered due to the field-line curvature, which then leads to isotropization of energetic particle distributions and particle precipitation to the Earth's atmosphere. Measurements of these precipitation at low-altitude spacecraft are thus often used to remotely probe the magnetotail current sheet configuration. This configuration may include spatially localized maxima of the curvature radius at equator (due to localized humps of the equatorial magnetic field magnitude) that reduce the energetic particle scattering and precipitation. Therefore, the measured precipitation patterns are related to the spatial distribution of the equatorial curvature radius that is determined by the magnetotail current sheet configuration. In this study, we show that, contrary to previous thoughts, the magnetic field line configuration with the localized curvature radius maximum can actually enhance the scattering and subsequent precipitation. The spatially localized magnetic field dipolarization (magnetic field humps) can significantly curve magnetic field lines far from the equator and create off-equatorial minima in the curvature radius. Scattering of energetic particles in these off-equatorial regions alters the scattering (and precipitation) patterns, which has not been studied yet. We discuss our results in the context of remote-sensing the magnetotail current sheet configuration with low-altitude spacecraft measurements.

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Configuration of the Earth’s Magnetotail Current Sheet

Cited by 18 publications

References 76 publications

Thin Current Sheet Behind the Dipolarization Front

Thin Current Sheet Behind the Dipolarization Front

Configuration of Magnetotail Current Sheet Prior to Magnetic Reconnection Onset

Charged particle scattering in dipolarized magnetotail

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