Suprathermal electron acceleration in magnetic reconnection

Hoshino, Masahiro; Mukai, T.; Terasawa, T.; Shinohara, I.

doi:10.1029/2001ja900052

Cited by 347 publications

(390 citation statements)

References 51 publications

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“…However, the energy gain required by the observation is much larger than a factor of 6 and therefore the complete acceleration mechanism still remains unresolved. In addition, the many wave features observed in the plasma sheet may break the adiabatic motion as discussed by Drake et al [2003] and Hoshino et al [2001]. Lastly, the readers should keep in mind that non-adiabatic acceleration such as waveparticle interactions are important although they are not discussed here.…”

Section: Summary and Discussionmentioning

confidence: 99%

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

Fritz

Larvaud

et al. 2006

Geophysical Research Letters

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The Cluster satellites observed a distinct pattern in the evolution of energetic electron pitch angle distributions on November 13, 2003, in the mid‐tail (radius >10RE) associated with intensifications of these electron fluxes that accompanied an observed local dipolarization of the magnetic field. The intensity of electrons (20–200 keV) were first observed to increase for perpendicular pitch angles (pancake distribution), then evolve into isotropic distributions, then further evolve into mixed distributions ‐ a combination of perpendicularly peaked distributions and beamlike distributions (cigar distribution), and at the end of each of three episodes always evolved into a beamlike or field‐aligned distribution. This evolution pattern seen at a relative fixed observing (satellite) location usually developed within the locally observed dipolarization time scale. We have interpreted this pattern to indicate that electrons were coming from different regions along the magnetotail and have gotten accelerated differently. This has led us to suggest and present a model in which Fermi acceleration dominates for electrons that are accelerated from the reconnection region, while betatron acceleration dominates for electrons that are accelerated from the mid‐tail region that is very close to the satellite location.

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Section: Summary and Discussionmentioning

confidence: 99%

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

Fritz

Larvaud

et al. 2006

Geophysical Research Letters

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“…2f). The localized betatron mechanism we propose here is different from the global betatron mechanism, which accelerates electrons during the ∇B drift opposite to a finite electric field 25 . If electrons bounce along the magnetic field line and simultaneously the length of the field line is shrinking (for example, the earthward-moving flux tubes in the Earth's magnetotail or the downward-moving flux tubes in the solar chromosphere), Fermi acceleration is expected.…”

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confidence: 93%

Energetic electron acceleration by unsteady magnetic reconnection

Fu¹,

Khotyaintsev²,

Vaivads³

et al. 2013

Nature Phys

245

246

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The mechanism that produces energetic electrons during magnetic reconnection is poorly understood. This is a fundamental process responsible for stellar flares 1,2 , substorms 3,4 , and disruptions in fusion experiments 5,6 . Observations in the solar chromosphere 1 and the Earth's magnetosphere 7-10 indicate significant electron acceleration during reconnection, whereas in the solar wind, energetic electrons are absent 11 . Here we show that energetic electron acceleration is caused by unsteady reconnection. In the Earth's magnetosphere and the solar chromosphere, reconnection is unsteady, so energetic electrons are produced; in the solar wind, reconnection is steady 12 , so energetic electrons are absent 11 . The acceleration mechanism is quasi-adiabatic: betatron and Fermi acceleration in outflow jets are two processes contributing to electron energization during unsteady reconnection. The localized betatron acceleration in the outflow is responsible for at least half of the energy gain for the peak observed fluxes.

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“…As the primary acceleration mechanism, electrons are accelerated by the reconnection electric field in the X-line region, and then may be further accelerated in the pileup region owing to curvature and gradient drifts along the electric field [9,26]. In addition, electrons can be accelerated by contracting magnetic islands via Fermi acceleration [24].…”

Section: Discussionmentioning

confidence: 99%

“…Various acceleration mechanisms have been proposed to interpret the origin of the energetic electrons during magnetic reconnection with or without guide field [9,[24][25][26]. As the primary acceleration mechanism, electrons are accelerated by the reconnection electric field in the X-line region, and then may be further accelerated in the pileup region owing to curvature and gradient drifts along the electric field [9,26].…”

Section: Discussionmentioning

confidence: 99%

“…Recently, there were many observations of reconnection in the solar wind, which were often associated with interplanetary coronal mass ejection (ICME) [6][7][8]. Energetic electrons are important offspring of magnetic reconnection [9,10] and are observed in different magnetospheres [10][11][12][13][14]. Øieroset et al [14] reported energetic electrons, with energy up to 300 keV, in the reconnection diffusion region of the Earth's magnetotail.…”

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confidence: 99%

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Energetic electrons associated with magnetic reconnection in the sheath of interplanetary coronal mass ejection

et al. 2012

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Magnetic reconnection is an important universal plasma dissipation process that converts magnetic energy into plasma thermal and kinetic energy, and simultaneously changes the magnetic field topology. In this paper, we report the first observation of energetic electrons associated with asymmetric reconnection in the sheath of an interplanetary coronal mass ejection. The magnetic field shear angle was about 151°, implying guide-field reconnection. The width of the exhaust was about 8×10 4 km. The reconnection rate was estimated as 0.044-0.08, which is consistent with fast reconnection theory and previous observations. We observed flux enhancements of energetic electrons with energy up to 400 keV in this reconnection exhaust. The region where energetic electron fluxes were enhanced is located at one pair of separatrices in the higher density hemisphere. We discuss these observation results, and compare with previous observations and recent kinetic simulations.

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Suprathermal electron acceleration in magnetic reconnection

Cited by 347 publications

References 51 publications

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

Energetic electron acceleration by unsteady magnetic reconnection

Energetic electrons associated with magnetic reconnection in the sheath of interplanetary coronal mass ejection

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