Model of a Thin Current Sheet in the Earth’s Magnetotail with a Kinetic Description of Magnetized Electrons

Мингалев, О. В.; Malova, H. V.; Мингалев, И. В.; Melnik, M. N.; Сецко, П. В.; Zelenyǐ, L. M.

doi:10.1134/s1063780x18100082

Cited by 10 publications

(12 citation statements)

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“…The preferentially field‐aligned anisotropic cold electrons (probably of the ionospheric origin; see, e.g., Walsh et al, ) provide p ‖, e / p ⊥, e ∼1.1 in the quiet magnetotail (Artemyev et al, ; Walsh et al, ). For some CSs, the contribution of electron anisotropy to j y can reach 100%, that is, the current density can be fully attributed to the electron anisotropy, (1/ μ 0 )( p ‖, e − p ⊥, e )( ∂B x / ∂z )/ B 2 (Artemyev et al, , , Mingalev et al, ). However, statistical estimates of the electron anisotropy are too low to explain the observed j y (Artemyev et al, ).…”

Section: Introductionmentioning

confidence: 99%

Ion Anisotropy in Earth's Magnetotail Current Sheet: Multicomponent Ion Population

et al. 2019

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The configuration and stability of the magnetotail current sheet, which determine the dynamics of the entire magnetosphere, largely depend on the ion kinetics as inferred from the velocity distribution function. This distribution is shaped by various transient acceleration processes and by contributions from the ionosphere and the distant magnetotail. Investigating the ion distribution is thus crucially important for adequate modeling of the current sheet stability. This necessitates spacecraft observations of the ion distribution in a wide energy range, from ionospheric outflow energies (below 1 keV) to high energies (approximately hundreds of kiloelectron volts). Using combined measurements of Electrostatic Analyzer and Solid State Telescope onboard Time History of Events and Macroscale Interactions during Substorms in 2008–2009 tail seasons, we demonstrate that the ion distribution in the quiet magnetotail current sheet (at times devoid of fast plasma flows and large electric fields) consists of three populations: a subthermal field‐aligned anisotropic population (contributing ∼90% to the total density but only ∼20% to the total pressure), an isotropic thermal population (contributing ∼10% of the total density and ∼60% of the total pressure), and a transversely anisotropic suprathermal population (contributing <1% of the total density and ∼20% of the total pressure). The suprathermal population may include high‐energy ions moving along transient (Speiser) orbits. The competing effects of subthermal and suprathermal partial pressure anisotropies result in an almost isotropic total (combined) ion pressure. We characterize the dependence of the ion distribution characteristics, including the anisotropy of different populations on local plasma sheet activity (ion flows and electric fields). We discuss the implications of our results for current sheet modelling.

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Section: Introductionmentioning

confidence: 99%

Ion Anisotropy in Earth's Magnetotail Current Sheet: Multicomponent Ion Population

et al. 2019

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“…This model version is a generalization of the initial version [Mingalev et al, 2018], in which the magnetic field has only one self-consistent shear symmetric component.…”

Section: Equations Of Numerical Model Of Spatially One-dimensional Tcsmentioning

confidence: 99%

“…The main features of the technique for numerical solution of the stationary Vlasov equation are discussed in detail in [Mingalev et al, 2018]. In this case, in the course of the numerical solution of the Vlasov equation for protons, we calculated their density n(z)=n i (z), the current density, and the stress tensor components defined in (1.5).…”

Section: Examples Of Force Balance In a Thin Current Sheetmentioning

confidence: 99%

“…Note that the development of numerical and approximate analytical models of stationary TCS with the normal magnetic field component has a long history, which is described in the reviews [Zelenyi et al, 2011[Zelenyi et al, , 2016 and in [Mingalev et al, 2018]. Analytical models represent protons in the quasi-adiabatic approximation [Kropotkin et al, 1995], and the most advanced models describe electrons in the so-called semi-fluid approximation (see, e.g., [Sitnov et al, 2000;Zelenyi et al, 2011]).…”

Section: Introductionmentioning

confidence: 99%

“…In our TCS model [Mingalev et al, 2018], the analytical description of magnetized electrons has been improved and has become totally kinetic. They are described by a Maxwell-Boltzmann distribution, which, depending on the formulation of the problem, is either an exact or approximate solution of the Vlasov equation in the drift approximation.…”

Section: Introductionmentioning

confidence: 99%

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Force balance in current sheets in collisionless plasma

Мингалев

Сецко

Melnik

et al. 2021

Solar-Terrestrial Physics

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In this paper, we derive a divergent form of the force balance equation for collisionless plasma in the quasineutrality approximation, in which the electric field and current density are excluded. For a stationary spatially one-dimensional current sheet with a constant normal component of the magnetic field and magnetized electrons, the general form of the force balance equation has been obtained for the first time in the form of a conservation law. An equation in this form is necessary for the correct formulation of boundary conditions when modeling asymmetric current sheets, as well as for the control of the stationarity of the numerical solution obtained in the model. Furthermore, the fulfillment of this equation is considered for two types of stationary configurations of a thin current sheet, which are obtained using a numerical model. The derived equation makes it possible to develop models of asymmetric current sheets, in particular current sheets on the magnetopause flanks in the magnetotail.

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Contribution of Anisotropic Electron Current to the Magnetotail Current Sheet as a Function of Location and Plasma Conditions

et al. 2020

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The magnetotail current sheet carries the current responsible for the largest fraction of the energy storage in the magnetotail, the magnetic energy in the lobes. It is thus inextricably linked with the dynamics and evolution of many magnetospheric phenomena, such as substorms. The magnetotail current sheet structure and stability depend mostly on the kinetic properties of the plasma populating the magnetotail. One of the most underinvestigated properties of this plasma is electron temperature anisotropy, which may contribute a large fraction of the total current. Using observations from five missions in the magnetotail, we examine the electron temperature anisotropy, T e|| ∕T e⟂ , and its potential contribution to the current density, quantified by the firehose parameter ( e|| − e⟂ )∕2, across y ∈ [−20, 20]R E and x ∈ [−100, −10]R E . We find that a significant fraction (>30%) of all current sheets have an anisotropic electron current density >10% of the total current. These current sheets form two distinct groups: (1) near-Earth (<30 R E ) accompanied by weak plasma flows (<100 km/s) and enhanced equatorial magnetic field (>3 nT) and (2) middle tail (>40 R E ) accompanied by fast plasma flows (>300 km/s) and small equatorial magnetic field (≤1 nT). For a significant number of near-Earth current sheets, the anisotropic electron current can be >25% of the total current density. Our findings suggest that electron temperature anisotropy should be included in current sheet models describing realistic magnetotail structure and dynamics.

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Model of a Thin Current Sheet in the Earth’s Magnetotail with a Kinetic Description of Magnetized Electrons

Cited by 10 publications

References 42 publications

Ion Anisotropy in Earth's Magnetotail Current Sheet: Multicomponent Ion Population

Ion Anisotropy in Earth's Magnetotail Current Sheet: Multicomponent Ion Population

Force balance in current sheets in collisionless plasma

Contribution of Anisotropic Electron Current to the Magnetotail Current Sheet as a Function of Location and Plasma Conditions

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