Profile of strong magnetic field By component in magnetotail current sheets

Rong, Zhaojin; Wan, Weixing; Shen, C.; Li, X.; Dunlop, M. W.; Petrukovich, A. A.; Hau, L.‐N.; Zhang, T. L.; Rème, H.; Du, Aimin; Lucek, E.

doi:10.1029/2011ja017402

Cited by 35 publications

(54 citation statements)

References 63 publications

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“…Since, in tilted CSs, B y B z (Petrukovich et al, 2006), there is significant field-aligned current near the neutral plane (Shen et al, 2008). In this respect strongly titled CSs are similar to horizontal CSs with substantial B y component (Rong et al, 2012). In this paper we compare properties of strongly tilted and horizontal CSs and discuss the nature of the current in strongly tilted CSs.…”

Section: Y Vasko Et Al: Statistical Study Of Strongly Tilted Curmentioning

confidence: 99%

The structure of strongly tilted current sheets in the Earth magnetotail

et al. 2014

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Abstract. We investigate strongly tilted (in the y-z GSM plane) current sheets (CSs) in the Earth magnetotail using data from the Cluster mission. We analyze 29 CS crossings observed in [2001][2002][2003][2004]. The characteristic current density, magnetic field at the CS boundary and the CS thickness of strongly tilted CSs are similar to those reported previously for horizontal (not tilted) CSs. We confirm that strongly tilted CSs are generally characterized by a rather large northward component of the magnetic field. The field-aligned current in strongly tilted CSs is on average two times larger than the transverse current. The proton adiabaticity parameter, κ p , is larger than 0.5 in 85 % of strongly tilted CSs due to the large northward magnetic field. Thus, the proton dynamics is stochastic for 18 current sheets with 0.5 < κ p < 3 and protons are magnetized for 6 sheets with κ p > 3, whereas electrons are magnetized for all observed current sheets. Strongly tilted CSs provide a unique opportunity to measure the electric field component perpendicular to the CS plane. We find that most of the electric field perpendicular to the CS plane is due to the decoupling of electron and ion motions (plasma polarization). For 27 CSs we determine profiles of the electrostatic potential, which is due to the plasma polarization. Drops in the potential between the neutral plane and the CS boundary are within the range of 200 V to 12 kV, while maximal values of the electric field are within the range of 0.2 mV m −1 to 8 mV m −1 . For 16 CSs the observed potentials are in accordance with Ohm's law, if the electron current density is assumed to be comparable to the total current density. In 15 of these CSs the profile of the polarization potential is approximately symmetric with respect to the neutral plane and has minimum therein.

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Section: Y Vasko Et Al: Statistical Study Of Strongly Tilted Curmentioning

confidence: 99%

The structure of strongly tilted current sheets in the Earth magnetotail

et al. 2014

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“…Thus, all particles cross the neutral plane moving along trajectories, which can be described by the guiding-centre theory. This effect of asymmetry of the CS interaction with particles can play an important role in the Earth's magnetotail, where B y is provided by penetration of the interplanetary magnetic field (Cowley, 1981;Wing et al, 1995), by deformation of the neutral plane (Petrukovich, 2009) or by local currents (Artemyev, 2011;Rong et al, 2012). Particles usually come to the CS of the Earth's magnetotail from the sources in the Southern and Northern Hemisphere.…”

Section: Discussionmentioning

confidence: 99%

“…This requirement can be written as a kinetic equation df/dt = 0 for the distribution function of particles f , where d/dt is the total derivative (Pitaevskii and Lifshitz, 1981). Absence of particle collisions results in the conservation of the phase volume, and forbids directed drifts of particles in the invariant space (Sinitsyn et al, 2011), i.e.…”

Section: Discussionmentioning

confidence: 99%

Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects

Artemyev

Neishtadt

Zelenyǐ

2013

Nonlin. Processes Geophys.

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Abstract. We investigate dynamics of charged particles in current sheets with the sheared magnetic field. In our previous paper (Artemyev et al., 2013) we studied the particle motion in such magnetic field configurations on the basis of the quasi-adiabatic theory and conservation of the quasiadiabatic invariant. In this paper we concentrate on violation of the adiabaticity due to jumps of this invariant and the corresponding effects of stochastization of a particle motion. We compare effects of geometrical and dynamical jumps, which occur due to the presence of the separatrix in the phase plane of charged particle motion. We show that due to the presence of the magnetic field shear, the average value of dynamical jumps is not equal to zero. This effect results in the decrease of the time interval necessary for stochastization of trapped particle motion. We investigate also the effect of the magnetic field shear on transient trajectories, which cross the current sheet boundaries. Presence of the magnetic field shear leads to the asymmetry of reflection and transition of particles in the current sheet. We discuss the possible influence of single-particle effects revealed in this paper on the current sheet structure and dynamics.

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“…On the other hand, Cluster data have shown the presence of CSs with a strong shear component (B y ∼ B 0 ) having uniform (Shen et al, 2008a;Rong et al, 2012) or bell-shape (Nakamura et al, 2008;Rong et al, 2012;Grigorenko et al, 2013) profiles. Due to the strong B y the current has a significant field-aligned component.…”

Section: Yvasko Et Al: Thin Current Sheets With Strong B Ymentioning

confidence: 99%

“…These CSs represent only a subclass of CSs with strong B y . The separate study is required for thicker CSs observed by Rong et al (2012) and Grigorenko et al (2013) in other periods of the Cluster mission.…”

Section: Yvasko Et Al: Thin Current Sheets With Strong B Ymentioning

confidence: 99%

Thin current sheets with strong bell-shape guide field: Cluster observations and models with beams

et al. 2014

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Abstract. We study the kinetic structure of intense ion-scale current sheets with strong electron currents and the guide field having a bell-shape profile. We consider four crossings of the Earth magnetotail current sheet by the Cluster mission in 2003. The thickness of these current sheets is about the ion inertial length and significantly smaller than the characteristic ion gyroradius. We analyze the asymmetry of the electron velocity distribution functions and show that the electron current is provided by the small electron subpopulation interpreted as an electron beam or two counter-streaming electron beams. The beam (counter-streaming beams) has a bulk velocity of the order of the electron thermal velocity and a density (difference of beam densities) of about 1-5 % of the plasma density. To describe the observed current sheets we develop a kinetic model with particle beams. The model predicts different thickness of the current sheet for different types of current carriers (one electron beam or two counterstreaming electron beams). The observed ion-scale current sheets can be explained assuming that the current is carried by one electron beam and a co-streaming ion beam. Although the ion beam does not carry a significant current, this beam is required to balance the electron current perpendicular to the current sheet neutral plane. The developed model explains the dominance of the electron current and the ion scales of the current sheets.

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Profile of strong magnetic field B_y component in magnetotail current sheets

Cited by 35 publications

References 63 publications

The structure of strongly tilted current sheets in the Earth magnetotail

The structure of strongly tilted current sheets in the Earth magnetotail

Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects

Thin current sheets with strong bell-shape guide field: Cluster observations and models with beams

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