Adiabatic Acceleration in a Magnetotail Flux Rope

Dahlin, Joel

doi:10.1029/2020gl087918

Cited by 2 publications

(1 citation statement)

References 60 publications

(85 reference statements)

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“…Nevertheless, direct identification of these acceleration mechanisms from in situ measurements is often challenging, partly due to the limited spatial and/or temporal resolution of the measurement. However, there is an important exception, namely the adiabatic processes of betatron and Fermi (curvature drift) acceleration, which act, respectively, on the perpendicular and parallel components of suprathermal electron pitch angle distributions, allowing the role of these mechanisms to be distinctly identified (Dahlin 2020;Fu et al 2020). In fact, the electron signatures of adiabatic acceleration mechanisms have been widely reported in planetary (mainly terrestrial) magnetotails (e.g., Fu et al 2011Fu et al , 2013Liu et al 2018;Zhong et al 2020;Guo et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Betatron Acceleration of Suprathermal Electrons within a Small-scale Flux Rope in the Solar Wind

Meng,

Guo,

Lin

et al. 2023

ApJL

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A growing body of evidence from observations, theories, and simulations indicates that particles can be effectively accelerated in solar wind regions filled with dynamic small-scale flux ropes (FRs). The main acceleration mechanisms identified in simulations include parallel electric field acceleration, first-order Fermi acceleration, and generalized betatron acceleration in contracting or merging small-scale FRs. However, direct identification of these acceleration mechanisms from in situ measurements remains a challenge. Here we present a distinct event of local betatron acceleration within a contracting small-scale FR in the solar wind, due to a local compression. In this event, the lower-energy halo electrons were effectively accelerated through the betatron mechanism, whereas the higher-energy suprathermal electrons predominated by the superhalo component were almost not energized. The halo electron energization processes via the betatron mechanism are reproduced using an analytical model. Further examination of small-scale FRs in the vicinity of the heliospheric current sheet over the period 1995–2020 indicates that in situ signatures of the betatron acceleration process are essentially elusive.

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Section: Introductionmentioning

confidence: 99%

Betatron Acceleration of Suprathermal Electrons within a Small-scale Flux Rope in the Solar Wind

Meng,

Guo,

Lin

et al. 2023

ApJL

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Particle Acceleration by Magnetic Reconnection in Geospace

Oka,

Birn,

Egedal

et al. 2023

Space Sci Rev

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Particles are accelerated to very high, non-thermal energies during explosive energy-release phenomena in space, solar, and astrophysical plasma environments. While it has been established that magnetic reconnection plays an important role in the dynamics of Earth’s magnetosphere, it remains unclear how magnetic reconnection can further explain particle acceleration to non-thermal energies. Here we review recent progress in our understanding of particle acceleration by magnetic reconnection in Earth’s magnetosphere. With improved resolutions, recent spacecraft missions have enabled detailed studies of particle acceleration at various structures such as the diffusion region, separatrix, jets, magnetic islands (flux ropes), and dipolarization front. With the guiding-center approximation of particle motion, many studies have discussed the relative importance of the parallel electric field as well as the Fermi and betatron effects. However, in order to fully understand the particle acceleration mechanism and further compare with particle acceleration in solar and astrophysical plasma environments, there is a need for further investigation of, for example, energy partition and the precise role of turbulence.

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Adiabatic Acceleration in a Magnetotail Flux Rope

Cited by 2 publications

References 60 publications

Betatron Acceleration of Suprathermal Electrons within a Small-scale Flux Rope in the Solar Wind

Betatron Acceleration of Suprathermal Electrons within a Small-scale Flux Rope in the Solar Wind

Particle Acceleration by Magnetic Reconnection in Geospace

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