Dipolarizing flux bundles in the cis‐geosynchronous magnetosphere: Relationship between electric fields and energetic particle injections

Liu, Jiang; Angelopoulos, V.; Zhang, Xiaojia; Turner, D. L.; Gabrielse, Christine; Li, Jinxing; Funsten, H. O.; Spence, H. E.

doi:10.1002/2015ja021691

Cited by 74 publications

(107 citation statements)

References 71 publications

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“…Figure d shows magnetic field fluctuations during this event, in Geocentric solar magnetospheric (GSM) coordinates. Bz is strongly enhanced at the injection front, indicating a dipolarization of the magnetic field (Liu et al, ). Figures e and f show spectrograms of electric and magnetic field wave power, respectively.…”

Section: Observationsmentioning

confidence: 99%

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

et al. 2018

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Now that observations have conclusively established that the inner magnetosphere is abundantly populated with kinetic electric field structures and nonlinear waves, attention has turned to quantifying the ability of these structures and waves to scatter and accelerate inner magnetospheric plasma populations. A necessary step in that quantification is determining the distribution of observed structure and wave properties (e.g., occurrence rates, amplitudes, and spatial scales). Kinetic structures and nonlinear waves have broadband signatures in frequency space, and consequently, high‐resolution time domain electric and magnetic field data are required to uniquely identify such structures and waves as well as determine their properties. However, most high‐resolution fields data are collected with a strong bias toward high‐amplitude signals in a preselected frequency range, strongly biasing observations of structure and wave properties. In this study, an ∼45 min unbroken interval of 16,384 samples/s field burst data, encompassing an electron injection event, is examined. This data set enables an unbiased census of the kinetic structures and nonlinear waves driven by this electron injection, as well as determination of their “typical” properties. It is found that the properties determined using this unbiased burst data are considerably different than those inferred from amplitude‐biased burst data, with significant implications for wave‐particle interactions due to kinetic structures and nonlinear waves in the inner magnetosphere.

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Section: Observationsmentioning

confidence: 99%

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

et al. 2018

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“…They then propagate earthward as an integral part of bursty bulk flows (BBFs) (Angelopoulos et al, ; Liu et al, ) over more than 10 R E for a few minutes (Birn et al, ; Runov et al, ) before eventually stopping near the inner edge of the plasma sheet (e.g., Dubyagin et al, ; Ohtani, Singer, & Mukai, ). Some (~1/3) of them may penetrate deep into the inner magnetosphere (within the GEO) (Liu et al, ). The leading edge of a DFB is characterized by a sharp enhancement of B z (in GSM, the default coordinate system of this paper unless otherwise specified) known as a dipolarization front (DF) (Nakamura, Matsumoto, & Fujimoto, ) or a reconnection front (Angelopoulos et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…This acceleration can be either adiabatic (Ashour‐Abdalla et al, ; Deng et al, ; Fu et al, ; Runov et al, ), most simply understood as caused by the electric field accompanying moving DFBs (e.g., Artemyev et al, ; Gabrielse et al, ; Zhou et al, ), or nonadiabatic due to large amplitude waves observed in the DFB vicinity (Zhou et al, ). For some DFBs that can penetrate into the inner magnetosphere, the electric field related to the DFB evolution can still be large and lead to significant local particle acceleration (Liu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Ultralow Frequency Waves Deep Inside the Inner Magnetosphere Driven by Dipolarizing Flux Bundles

et al. 2017

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Dipolarizing flux bundles (DFBs) are small flux tubes (typical cross‐tail scale of 1–3 RE) in the nightside magnetosphere that have magnetic field more dipolar than the background. They are generated at or beyond 20 RE downtail and then travel earthward. Although DFBs usually stop before reaching the geosynchronous orbit (GEO), they may still transfer some portion of their energy into the inner magnetosphere by radiating ULF waves. We show the clearest evidence of this process, to date, using in situ data from a fleet of spacecraft and ground stations. We illustrate that a typical DFB stopped before reaching GEO but excited Pi2 waves that filled a volume of space extending from the plasma sheet to deep inside the plasmasphere. This event provides the first in situ, direct link between stopped DFBs and ULF waves deep inside the inner magnetosphere (as deep as L = 3). The waves were attenuated when traveling away from the DFB, but even at L = 3 (XGSM = −2.2), they were still traveling with a significant earthward Poynting flux. In addition, we observed evidence of interaction between these waves and electrons at GEO.

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“…Similar acceleration deep inside geosynchronous orbit may require even larger electric fields. According to a recent statistical study [Liu et al, 2016], the electric fields associated with mesoscale injections inside geosynchronous can be as large as ≳10 mV/m, but on average do not exceed 6 mV/m.…”

Section: 1002/2016ja023304mentioning

confidence: 99%

“…Gkioulidou et al [2015] reported a dispersionless ion injections at as low as L = 5.5 associated with a sharp dipolarization of magnetic field, similar to dipolarization fronts in the magnetotail. A statistical analysis of dipolarization fronts measured at Van Allen Probes [Liu et al, 2016] showed that as much as 30% of dipolarizations from the magnetotail can penetrate inside geosynchronous orbit.…”

Section: 1002/2016ja023304mentioning

confidence: 99%

Ion acceleration at dipolarization fronts in the inner magnetosphere

et al. 2017

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During geomagnetic storms plasma pressure in the inner magnetosphere is controlled by energetic ions of tens to hundreds of keV. Plasma pressure is the source of global storm time currents, which control the distribution of magnetic field and couple the inner magnetosphere and the ionosphere. Recent analysis showed that the buildup of hot ion population in the inner magnetosphere largely occurs in the form of localized discrete injections associated with sharp dipolarizations of magnetic field, similar to dipolarization fronts in the magnetotail. Because of significant differences between the ambient magnetic field and the dipolarization front properties in the magnetotail and the inner magnetosphere, the physical mechanisms of ion acceleration at dipolarization fronts in these two regions may also be different. In this paper we discuss a new acceleration mechanism enabled by stable trapping of ions at the azimuthally localized dipolarization fronts. It is shown that trapping can provide a robust mechanism of ion energization in the inner magnetosphere even in the absence of large electric fields.

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Dipolarizing flux bundles in the cis‐geosynchronous magnetosphere: Relationship between electric fields and energetic particle injections

Cited by 74 publications

References 71 publications

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

Ultralow Frequency Waves Deep Inside the Inner Magnetosphere Driven by Dipolarizing Flux Bundles

Ion acceleration at dipolarization fronts in the inner magnetosphere

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