Plasma sheet thickness during a bursty bulk flow reversal

Panov, E. V.; Nakamura, R.; Baumjohann, W.; Сергеев, В. А.; Petrukovich, A. A.; Angelopoulos, V.; Volwerk, M.; Retinò, Alessandro; Takada, T.; Glaßmeier, Karl‐Heinz; McFadden, J. P.; Larson, D. E.

doi:10.1029/2009ja014743

Cited by 64 publications

(99 citation statements)

References 67 publications

(103 reference statements)

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“…Our simulation confirms that this sequence is due to an expansion and thinning, rather than to a downward and upward motion, of the plasma sheet. This is also consistent with conclusions from THEMIS observations [Panov et al, 2010b].…”

Section: Flow Braking and Vortex Formationsupporting

confidence: 93%

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

et al. 2011

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[1] Using three-dimensional MHD simulations of magnetic reconnection in the magnetotail, we investigate the fate of earthward bursty bulk flows (BBFs). The flow bursts are identified as entropy-depleted magnetic flux tubes ("bubbles") generated by the severance of a plasmoid via magnetic reconnection. The onset of fast reconnection coincides closely with a drastic entropy reduction at the onset of lobe reconnection. The fact that, in the simulation, the Alfvén speed does not change significantly at this time suggests that the destabilization of ballooning/interchange modes is important in driving faster reconnection as well as in providing cross-tail structure. In the initial phase, the BBFs are associated with earthward propagating dipolarization fronts. When the flow is stopped nearer to Earth, the region of dipolarization expands both azimuthally and tailward. Tailward flows are found to be associated with a rebound of the earthward flow and with reversed vortices on the outside of the flow. Earthward and tailward flows are also associated with expansion and contraction of the near plasma sheet. All of these features are consistent with recent satellite observations by Cluster and the Time History of Events and their Macroscopic Interactions during Substorms (THEMIS) mission.Citation: Birn, J., R. Nakamura, E. V. Panov, and M. Hesse (2011), Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection,

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Section: Flow Braking and Vortex Formationsupporting

confidence: 93%

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

et al. 2011

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“…The BBF is represented by the earthward plasma flow (light green) together with flow braking and diversion closer to the inner plasma sheet boundary. Possible BBF return flows are also indicated by the green dashed arrows [Chen and Wolf, 1999;Kauristie et al, 2000;Birn et al, 2004;Keiling et al, 2009;Ohtani et al, 2009;Walsh et al, Panov et al, 2010a, 2010b. The shear and twisting of the magnetic field at the flanks of the BBF causes fieldaligned currents (magenta) connecting to the auroral iono- Figure 1.…”

Section: Theoretical Motivationmentioning

confidence: 99%

“…As shown by Birn et al [2004], flow vortices appear at the flanks of the bubble, twisting the magnetic field, and causing a downward (upward) field-aligned current at the dawnside (duskside) flank, and forming a local wedge like current system [e.g., Wolf, 1993, 1999;Sergeev et al, 1996a;Birn and Hesse, 1996;Birn et al, 1999Birn et al, , 2004Snekvik et al, 2007;Zhang et al, 2009]. A return plasma flow may occur at the flanks of the bubble, and the corresponding shear against the plasma flow in the bubble main channel may also be involved in the generation of the field-aligned currents [e.g., Chen and Wolf, 1999;Kauristie et al, 2000;Birn et al, 2004;Keiling et al, 2009;Ohtani et al, 2009;Walsh et al, 2009;Panov et al, 2010aPanov et al, , 2010bBirn et al, 2011;Ge et al, 2011;Pitkänen et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

Energy conversion regions as observed by Cluster in the plasma sheet

et al. 2011

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[1] In this article we present a review of recent studies of observations of localized energy conversion regions (ECRs) observed by Cluster in the plasma sheet at altitudes of 15-20R E . By examining variations in the power density, E · J, where E is the electric field and J is the current density, we show that the plasma sheet exhibits a high level of fine structure. Approximately three times as many concentrated load regions (CLRs) (E · J > 0) as concentrated generator regions (CGRs) (E · J < 0) are identified, confirming the average load character of the plasma sheet. Some ECRs are found to relate to auroral activity. While ECRs are relevant for the energy conversion between the electromagnetic field and the particles, bursty bulk flows (BBFs) play a central role for the energy transfer in the plasma sheet. We show that ECRs and BBFs are likely to be related, although details of this relationship are yet to be explored. The plasma sheet energy conversion increases rather simultaneously with increasing geomagnetic activity in both CLRs and CGRs. Consistent with large-scale magnetotail simulations, most of the observed ECRs appear to be rather stationary in space but varying in time. We estimate that the ECR lifetime and scale size are a few minutes and a few R E , respectively. It is conceivable that ECRs rise and vanish locally in significant regions of the plasma sheet, possibly oscillating between load and generator character, while some energy is transmitted as Poynting flux to the ionosphere.

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“…According to the spacecraft observations, dipolarization fronts originate in the reconnection region in the deep (or middle) magnetotail of planetary magnetospheres (Runov et al 2012;Kasahara et al 2013) and propagate toward the planets without substantial evolution of the magnetic field configuration (Runov et al 2009). In the vicinity of the region with the strong dipole (planet) magnetic field, these fronts are braking (e.g., Nakamura et al 2009;Zieger et al 2011) and can even change the direction of propagation (Panov et al 2010;Birn et al 2011;Nakamura et al 2013). It should be underlined that certain signatures of dipolarization fronts are found in the reconnection region in the solar corona as well (Reeves et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…The front can slow down due to propagation toward the region with increased magnetic field (Nakamura et al 2009;Panov et al 2010;Birn et al 2011). Effects of such front evolution on particle acceleration were not considered before.…”

Section: Introductionmentioning

confidence: 99%

Preferential acceleration of heavy ions in the reconnection outflow region

Artemyev

Zimbardo

Ukhorskiy

et al. 2014

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Context. Many observations show that heating in the solar corona should be more effective for heavy ions than for protons. Moreover, the efficiency of particle heating also seems to be larger for a larger particle electric charge. The transient magnetic reconnection is one of the most natural mechanisms of charged particle acceleration in the solar corona. However, the role of this process in preferential acceleration of heavy ions has still yet to be investigated. Aims. In this paper, we consider charged particle acceleration in the reconnection outflow region. We investigate the dependence of efficiency of various mechanisms of particle acceleration on particle charge and mass. Methods. We take into account recent in situ spacecraft observations of the nonlinear magnetic waves that have originated in the magnetic reconnection. We use analytical estimates and test-particle trajectories to study resonant and nonresonant particle acceleration by these nonlinear waves. Results. We show that resonant acceleration of heavy ions by nonlinear magnetic waves in the reconnection outflow region is more effective for heavy ions and/or for ions with a larger electric charge. Nonresonant acceleration can be considered as a combination of particle reflections from the front of the nonlinear waves. Energy gain for a single reflection is proportional to the particle mass, while the maximum possible gain of energy corresponds to the classical betatron heating. Conclusions. Small-scale transient magnetic reconnections produce nonlinear magnetic waves propagating away from the reconnection region. These waves can effectively accelerate heavy ions in the solar corona via resonant and nonresonnat regimes of interactions. This mechanism of acceleration is more effective for ions with a larger mass and/or with a larger electric charge.

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Plasma sheet thickness during a bursty bulk flow reversal

Cited by 64 publications

References 67 publications

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

Energy conversion regions as observed by Cluster in the plasma sheet

Preferential acceleration of heavy ions in the reconnection outflow region

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