Current carriers in the bifurcated tail current sheet: Ions or electrons?

Israelevich, P. L.; Ershkovich, A. I.; Oran, R.

doi:10.1029/2007ja012541

Cited by 21 publications

(27 citation statements)

References 48 publications

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“…However, in agreement with the previous investigations j curl and proton current are only weakly correlated Israelevich et al, 2008). One could conclude that there exists some mechanism of decreasing proton current and increasing electron one, while preserving the total current.…”

Section: Discussionsupporting

confidence: 80%

“…1a). This result agrees with the similar earlier findings for bifurcated CS (Israelevich et al, 2008) and thin CS . Electron currents are always positive and generally better correspond to j curl (Fig.…”

Section: Observational Datasupporting

confidence: 83%

“…Another important problem of CS structure is a weak correlation between current density measured with the help of the curlometer technique (j curl = c 4π rotB) and that obtained from proton flows Israelevich et al, 2008). This result (see Sect.…”

Section: Introductionmentioning

confidence: 60%

“…Ion bulk velocity related to diamagnetic drift and quasi-adiabatic motion should be much larger than electron bulk velocity (in the system without electric field). To explain the dominant electron current one can use the assumption about particle cross field drift (Asano et al, 2004;Israelevich et al, 2008). It means that coordinate system in which CS does not move has some velocity in negative direction.…”

Section: Observational Datamentioning

confidence: 99%

“…For example, CS bifurcation (double-peaked current density) was first reported in GEOTAIL observations by Hoshino et al (1996). With the recent observations of bifurcated CS by CLUSTER (Sergeev et al, 2003;Thompson et al, 2006;Israelevich et al, 2008) it became possible to perform thorough comparisons with theories (Zelenyi et al, 2002;Sitnov et al, 2006). …”

Section: Introductionmentioning

confidence: 99%

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Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

et al. 2009

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Abstract. Kinetic structure of embedded thin horizontal current sheets is investigated. Current density estimated by curlometer technique is in general agreement with a sum of electron and proton currents. Embedding of observed thin current sheets in the much wider plasma sheet is apparent in the current density profiles. Ion velocity distributions consist of two parts: the cold non-drifting core likely belongs to the plasma sheet background, while the hotter asymmetric "wings" carry the main portion of the current. Oxygen ions (if present) and higher-energy tails of distribution function can contribute up to 30% of the total current. We compared current density profiles across sheets with three typical current sheet models. Models which allow embedding, describe observed structures equally well at the level of experimental accuracy.

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Section: Discussionsupporting

confidence: 80%

Section: Observational Datasupporting

confidence: 83%

Section: Introductionmentioning

confidence: 60%

Section: Observational Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

et al. 2009

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Electron pitch angle/energy distribution in the magnetotail

et al. 2014

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In this paper we utilize 9 years of Cluster observations in the Earth's magnetotail to investigate electron pitch angle/energy distributions. We mainly concentrate on the population of anisotropic electrons with a dominance of the parallel phase space density and energies larger than 100 eV. The energy distribution of this population strongly varies with the downtail distance (the near-Earth x > −12 R E and the tail x ∈ [−20, −12] R E ) and along the dawn-dusk direction (the midnight |y| < 10 R E and the flanks |y| > 10 R E ). In the tail-midnight domain the electron anisotropic population is present at all energy ranges up to 20 keV, while at the tail-flank domain only the energy range below several keV is filled by this population. In the near-Earth domain the only anisotropic electrons are cold, with energies less than 1 keV. We investigate the dependence of the energy distribution of the anisotropic electron population on the system parameters for the midnight-tail domain where the main statistics is collected. The increase of the B z GSM component of the magnetic field corresponds to an increasing energy range filled by anisotropic electrons. The increase of the electron temperature anisotropy is provided by the enhancement of the anisotropic population at all energies up to 20 keV. There is no distinct dependence of the electron anisotropic population on the plasma flow velocity. The increase of the electron temperature corresponds to shifting of the electron anisotropic population toward higher energies. We propose a simple model of the pitch angle/energy distribution of this electron population and discuss the origin of anisotropic electrons in the magnetotail.

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Where is the magnetic energy for the expansion phase of auroral substorms accumulated? 2. The main body, not the magnetotail

Akasofu

2017

JGR Space Physics

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It is suggested that the magnetosphere tries to stabilize itself by quickly unloading the magnetic energy accumulated within its main body, when the accumulated magnetic energy exceeds a limited amount, which can be identified as the energy for the expansion phase. It is this process which manifests as the impulsive expansion phase, during which auroral arcs advance well beyond the presubstorm latitude in the midnight sector. It was shown in the previous paper that the magnetotail does not have enough magnetic energy for a medium substorm (energy 5 × 1015 J; AE = 1000 nT). In this paper, it is shown that (1) the reason of the short lifetime (1–1.5 h) of the expansion phase is due to the fact that a limited amount of magnetic energy accumulated during the growth phase is dissipated in a period similar to the duration of the growth phase (1–1.5 h); the accumulation rate is similar to the dissipation rate during the expansion phase: (2) when the main body of the magnetosphere accumulates the magnetic energy, it is inflated; β (= (nkT/B2/8π)) even at XGSM = −6 RE becomes close to 1.0 for magnetic energy (2.9 × 1014 J) which is less than the amount consumed by a medium intensity substorm. (3) As a result, the plasma sheet current and thus the magnetosphere are expected to become unstable, unloading the accumulated excess magnetic energy and resulting in current reduction and deflation. (4) The resulting deflation can cause an earthward electric field of 5–50 mV/m, which can generate Bostrom's current system, which is mainly responsible in producing various phenomena of the expansion phase. (5) The large range of substorm intensity (AE = 100–2000 nT) is likely to be due to the location where the energy is accumulated; the closer is the distance to the Earth (XGSM between −10 RE and −4 RE), the more intense the substorm intensity is.

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Current carriers in the bifurcated tail current sheet: Ions or electrons?

Cited by 21 publications

References 48 publications

Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

Electron pitch angle/energy distribution in the magnetotail

Where is the magnetic energy for the expansion phase of auroral substorms accumulated? 2. The main body, not the magnetotail

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