Observations of parallel ion energization in the equatorial region

Quinn, J. M.; Southwood, D. J.

doi:10.1029/ja087ia12p10536

Cited by 86 publications

(66 citation statements)

References 8 publications

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“…They have also been observed at geosynchronous altitude by ATS-5 and ATS-6 [Quinn and Mcllwain, 1979;Quinn and Southwood, 1982]. In as shown in the Plate la.…”

Section: Introductionmentioning

confidence: 88%

Fast auroral snapshot observations of bouncing ion distributions: Fieldline length measurements

Boehm¹,

Klumpar²,

Möbius³

et al. 1999

J. Geophys. Res.

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Abstract.Observations of 0.01~10 keV ions at a discrete set of velocities, as expected for ions bouncing repeatedly between hemispheres, have been previously reported both at low altitudes and at geosynchronous orbit. The following two possible models of the ion source have been suggested: for the geosynchronous observations, an equatorial-acceleration model involving temporally confined ion acceleration "events" and for the low-altitude observations, a model involving a "heating wall" in the auroral acceleration region from which ions subsequently drift to other latitudes. In the latter case, the spatially bounded source appears temporally bounded from the point of view of one field line drifting over it. We report here Fast Auroral Snapshot (FAST) observations of multienergy events near local noon at several thousand kilometer altitude and show that these events orginated in a temporally localized, spatially extended, equatorial source. The dispersion pattern for individual ion bands over latitude is consistent with such a source, and not with the heating wall hypothesis, the observed energy being proportional to the square of the modeled field line length. The latter condition on the dispersion is much more precise than any imposed by a latitudinal drift model. A fit of this model to Akebono and DMSP F8 data previously published by Hirahara et al. (1997) is also shown. The fit to two Akebono events is accurate at lower latitudes, where the magnetic field model is expected to be reliable. The fit to DMSP data corresponding to one of the Akebono events involves additional field-aligned potentials of roughly 100 eV in the auroral zone. Observations of dispersion events of this type are expected to be useful more generally. The "nonlocal" determination of the magnetic field line length can provide a check on magnetic field models. A match of the observed field line length to the modeled one provides for greatly increased confidence in magnetic mapping.

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“…They have also been observed at geosynchronous altitude by ATS-5 and ATS-6 [Quinn and Mcllwain, 1979;Quinn and Southwood, 1982]. In as shown in the Plate la.…”

Section: Introductionmentioning

confidence: 88%

Fast auroral snapshot observations of bouncing ion distributions: Fieldline length measurements

Boehm¹,

Klumpar²,

Möbius³

et al. 1999

J. Geophys. Res.

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“…This suggests that the mechanisms of cross-tail acceleration and field collapse or dipolarization of the inner tail ("convection surge mechanism" [Lezniak and Winckler, 1970;Quinn and Southwood, 1982;Mauk, 1986]) are the major mechanisms responsible not only for ion acceleration and injection but also for electron injections in the inner magnetotail. The test orbits show that the electric field associated with the collapse is most significant for the inner edge of the region of enhanced electron fluxes (injection boundary), as well as for the ion injection boundary [Birn et al, 1997b].…”

Section: Stunmary and Discussionmentioning

confidence: 99%

Substorm electron injections: Geosynchronous observations and test particle simulations

Birn¹,

Thomsen²,

Borovsky³

et al. 1998

J. Geophys. Res.

192

208

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“…Early studies of the energetic electrons' pitch angle distributions during substorms included both modeling work and observational work. Modeling and observation work have shown that substorm induced electric fields accelerate electrons [Moore et al, 1981;Mauk, 1986;Aggson et al, 1983;Quinn and Southwood, 1982;Hesse, 1993, 1996;Birn et al, 1998Birn et al, , 2000.…”

Section: Introductionmentioning

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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Observations of parallel ion energization in the equatorial region

Cited by 86 publications

References 8 publications

Fast auroral snapshot observations of bouncing ion distributions: Fieldline length measurements

Fast auroral snapshot observations of bouncing ion distributions: Fieldline length measurements

Substorm electron injections: Geosynchronous observations and test particle simulations

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

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