Local structure of the magnetotail current sheet: 2001 Cluster observations

Runov, A.; Сергеев, В. А.; Nakamura, R.; Baumjohann, W.; Apatenkov, S.; Asano, Yasuhito; Takada, T.; Volwerk, M.; Vörös, Z.; Zhang, T. L.; Sauvaud, J. A.; Rème, H.; Balogh, A.

doi:10.5194/angeo-24-247-2006

Cited by 246 publications

(336 citation statements)

References 36 publications

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“…For both profiles, proton energies of up to 100 keV are obtained, in agreement with observations. When a small magnetic fluctuation level is present, A 0 / 1 nT, the proton 924 F. Catapano et al: Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail energy can easily reach 5-6 keV and He ++ and O + can reach 10 keV, in agreement with typical ion temperatures observed in the magnetotail (e.g, Baumjohann et al, 1989;Runov et al, 2006;Artemyev et al, 2011). For He ++ ions, notably, energies of up to 200 keV are obtained (see Fig.…”

Section: Discussionsupporting

confidence: 58%

“…Considering that the proton temperature in the magnetotail plasma sheet is observed to be of the order of 5 keV (e.g., Borovsky et al, 1997;Runov et al, 2006;Artemyev et al, 2011), a very small fluctuation level with δB ∼ 1 nT, almost always present in the magnetotail (Hoshino et al, 1994), is sufficient to heat the cold plasma coming from the solar wind to a temperature of 3-5 keV (Runov et al, 2006).…”

Section: Results For Protonsmentioning

confidence: 99%

“…We notice that T i ∼ 5T e most frequently in the magnetotail (e.g., Baumjohann et al, 1989;Runov et al, 2006), and this condition has an influence on the current carrying populations. Here, the condition T 0e = T 0i can be used because the background populations do not contribute to the current density.…”

Section: Introductionmentioning

confidence: 99%

“…Further, relevant levels of energetic electrons and ions are also observed during periods of low geomagnetic activity (Christon et al, 1989), leaving open the search for the acceleration mechanism. In addition, the observed proton temperatures, of the order of 5-10 keV, are also much larger than the energy corresponding to their original source, but the mechanism that can generate such heated particles is not fully understood (Runov et al, 2006;Artemyev et al, 2011). Grigorenko et al (2009) pointed out that 100 keV ions are accelerated near reconnecting regions, possibly by a process related to time-dependent, patchy reconnection.…”

Section: Introductionmentioning

confidence: 99%

“…While the Harris magnetic field profile is very popular in space plasmas, many observations in the Earth's magnetotail show that the current sheet has a non-Harris-like profile, with the current sheet being often embedded in a thicker plasma sheet (e.g., Runov et al, 2006). Recently, Catapano et al (2015) generalized the well-known solution of the Harris current sheet to the case where several current carrying populations, i.e., multiple electron and ion populations, are present.…”

Section: Introductionmentioning

confidence: 99%

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Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

et al. 2016

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Abstract. Spacecraft observations show that energetic ions are found in the Earth's magnetotail, with energies ranging from tens of keV to a few hundreds of keV. In this paper we carry out test particle simulations in which protons and other ion species are injected in the Vlasov magnetic field configurations obtained by Catapano et al. (2015). These configurations represent solutions of a generalized Harris model, which well describes the observed profiles in the magnetotail. In addition, three-dimensional time-dependent stochastic electromagnetic perturbations are included in the simulation box, so that the ion acceleration process is studied while varying the equilibrium magnetic field profile and the ion species. We find that proton energies of the order of 100 keV are reached with simulation parameters typical of the Earth's magnetotail. By changing the ion mass and charge, we can study the acceleration of heavy ions such as He ++ and O + , and it is found that energies of the order of 100-200 keV are reached in a few seconds for He ++ , and about 100 keV for O + .

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Section: Discussionsupporting

confidence: 58%

Section: Results For Protonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

et al. 2016

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Collisionless resistivity in a bifurcated current sheet

Andriyas

Spencer

2014

JGR Space Physics

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The collisionless resistivity due to charged particle chaos in spatially inhomogeneous magnetic fields is calculated for two frequently observed magnetotail current sheets, the X line, and a bifurcated current sheet (BCS) over varying strengths of cross-tail electric field. The calculation is done for two charged species, protons and O + ions, found in the magnetotail specially during active times. Chaotic behavior of the particles is studied for the chaos parameter ≈ 1 defined by Buchner and Zelenyi (1989) as the square root of minimum radius of curvature to the maximum particle gyroradius. The surface of section plot and maximal Lyapunov exponents are analyzed to compare the particle behavior in the two magnetic field topologies. It is found that the particle behavior in a BCS is chaotic around the two humps located at ±z 0 and that the configuration is more chaotic than the X line (maximum Lyapunov exponent for X line is around 0.25 compared to 0.34 for BCS). The collisionless resistivity is calculated using the technique developed by Numata and Yoshida (2003). The method relies on a phenomenological equivalence between the particle loss rate from the chaos region and rate of change of momentum in the chaos region under steady state conditions. Rapid decay of the particles from the chaos region is modeled with exponential fits, and it is found that a double exponent is needed for O + ions in an X line and for both species in the BCS. The resistivity thus calculated is found to be 9-10 orders of magnitude higher than the Spitzer resistivity.

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On the relation between asymmetries in the ring current and magnetopause current

Haaland

Gjerloev

2013

JGR Space Physics

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[1] Motion of charged particles in the Earth's magnetosphere sets up a system of currents. Current continuity requires that these currents are closed, either locally or via other current systems. In this paper, we have investigated whether magnetopause surface currents can contribute to ring current closure. Using measurements from the Cluster constellation of spacecraft, we calculated thickness and current density of the magnetopause current layer for a large number of flank magnetopause traversals. For each event, we consulted sectorial ring current indices, derived from SuperMAG-a large constellation of ground-based magnetometer stations. SuperMAG results show a significant and persistent dawn-dusk asymmetry in ground magnetic perturbations which indicates a more intense ring current on the duskside. The asymmetries become more pronounced during disturbed magnetospheric conditions, indicating an increased divergence of the current and closure through other current systems. A similar response to geomagnetic activity is also observed at the magnetopause. Duskside magnetopause current densities are generally higher than their dawnside counterparts, and also, the magnetopause asymmetry becomes more pronounced during disturbed conditions. Although the two current systems are related to different processes-gradient drift of energetic plasma sheet particles for the ring current and a surface current due to differential motion of ions and electrons inside the magnetopause interface for the magnetopause current-the results demonstrate a mutual relation between the two current systems.Citation: Haaland, S., and J. Gjerloev (2013), On the relation between asymmetries in the ring current and magnetopause current,

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Local structure of the magnetotail current sheet: 2001 Cluster observations

Cited by 246 publications

References 36 publications

Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

Proton and heavy ion acceleration by stochastic fluctuations in the Earth's magnetotail

Collisionless resistivity in a bifurcated current sheet

On the relation between asymmetries in the ring current and magnetopause current

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