Energetic electron bursts in the plasma sheet and their relation with BBFs

Duan, Aiying; Cao, Jinbin; Dunlop, M. W.; Wang, Z. Q.

doi:10.1002/2014ja020169

Cited by 56 publications

(55 citation statements)

References 97 publications

(153 reference statements)

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“…Previous work at the Earth has found that dipolarization fronts are often associated with increases in the flux of high‐energy electrons (Asano et al, ; Duan et al, ; Runov et al, , ). For the majority of terrestrial events the increase in high‐energy electrons (>1 keV) is accompanied by a decrease in the fluxes at lower energies (<1 keV; Deng et al, ; Pan et al, ; Runov et al, ).…”

Section: Introductionmentioning

confidence: 99%

Dipolarization Fronts With Associated Energized Electrons in Saturn's Magnetotail

et al. 2018

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We present a statistical study of dipolarization fronts within Saturn's magnetotail. Automated methods were used to identify 28 significant southward rotations of the field coupled with enhancements in the electron energy. The observed dipolarizations cover the majority of the magnetotail, though possess a strong dawn‐dusk asymmetry (79% occur postmidnight). Almost half (43%) of dipolarizations occur within 3 hr of another event, though these chains are solely observed postmidnight. Most pitch angle distributions of the heated electron populations show increased relative fluxes parallel or perpendicular to the field, likely due to nonlocal heating effects. The electron temperature and density following the passage of a front are anticorrelated; the temperature increases are accompanied by a decrease in their density. The temperature increases by factors of 4–12, while the density drops by factors of 3–10. Premidnight events consistently show the smallest relative heating and density depletion, suggesting they are observed closer to their generation. In contrast, the location of the postmidnight x‐line is inferred to be more variable, with a large variety of heating factors observed. Forty percent of the events show a strong reduction in water (W+) group fraction, likely related to either the preferential loss of equatorial heavy ions in departing plasmoids or the closure of open field. Two of these events show significant compositional changes suggesting the addition of plasma of external origin; we suggest that these events involved the closure of open field.

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Section: Introductionmentioning

confidence: 99%

Dipolarization Fronts With Associated Energized Electrons in Saturn's Magnetotail

et al. 2018

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“…Behind the DF, magnetic field strength is typically elevated to form a magnetic flux pileup region (FPR) [ Khotyaintsev et al ., ] or equivalently dipolarizing flux bundles [ Liu et al ., , ], which contain heated plasma proportion presumably originating from transient magnetic reconnection [ Fu et al ., ]. The electric structures at the DFs [ Zhou et al ., ; Fu et al ., ; Sun et al ., ] as well as the acceleration of electrons [e.g., Fu et al ., , ; Ashour‐Abdalla et al , ; Lu et al ., ; Duan et al ., ] and ions [e.g., Zhou et al ., ; Artemyev et al ., ] inside the FPRs have been widely reported. Usually, the electron acceleration can be attributed to either adiabatic process associated with betatron and Fermi mechanisms [ Fu et al ., , ; Liu et al ., ] or nonadiabatic process associated with wave‐particle interaction.…”

Section: Introductionmentioning

confidence: 99%

Broadband high‐frequency waves detected at dipolarization fronts

Yang

Cao

et al. 2017

JGR Space Physics

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Dipolarization front (DF) is a sharp boundary most probably separating the reconnection jet from the background plasma sheet. So far at this boundary, the observed waves are mainly in low‐frequency range (e.g., magnetosonic waves and lower hybrid waves). Few high‐frequency waves are observed in this region. In this paper, we report the broadband high‐frequency wave emissions at the DF. These waves, having frequencies extending from the electron cyclotron frequency fce, up to the electron plasma frequency fpe, could contribute ~10% to the in situ measurement of intermittent energy conversion at the DF layer. Their generation may be attributed to electron beams, which are simultaneously observed at the DF as well.

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“…In particular, Duan et al (2014) found that most energetic electrons in plasma sheet are directly or indirectly associated with magnetic reconnection, but some energetic electron burst is not caused by local acceleration. Actually we cannot determine the relative contribution of these two factors (local acceleration and drift-in effect) in any of the four structures.…”

Section: Discussion and Summarymentioning

confidence: 99%

Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study

Zhou

Deng³

et al. 2015

Ann. Geophys.

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Abstract. Magnetic reconnection has long been believed to be an efficient engine for energetic electrons production. Four different structures have been proposed for electrons being energized: flux pileup region, density cavity located around the separatrix, magnetic island and thin current sheet. In this paper, we compare the electron acceleration efficiency among these structures based on 12 magnetotail reconnection events observed by the Cluster spacecraft in [2001][2002][2003][2004][2005][2006]. We used the flux ratio between the energetic electrons (> 50 keV) and lower energy electrons (< 26 keV) to quantify the electron acceleration efficiency. We do not find any specific sequence in which electrons are accelerated within these structures, though the flux pileup region, magnetic island and thin current sheet have higher probabilities to reach the maximum efficiency among the four structures than the density cavity. However, the most efficient electron energization usually occurs outside these structures. We suggest that other structures may also play important roles in energizing electrons. Our results could provide important constraints for the further modeling of electron acceleration during magnetic reconnection.

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Energetic electron bursts in the plasma sheet and their relation with BBFs

Cited by 56 publications

References 97 publications

Dipolarization Fronts With Associated Energized Electrons in Saturn's Magnetotail

Dipolarization Fronts With Associated Energized Electrons in Saturn's Magnetotail

Broadband high‐frequency waves detected at dipolarization fronts

Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study

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