Near‐equatorial magnetospheric particles from ∼1 eV to ∼1 MeV

Young, D. T.

doi:10.1029/rg021i002p00402

Cited by 47 publications

(25 citation statements)

References 253 publications

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“…In his view, the injected plasma contains chiefly hydrogen, which is rapidly removed, leaving behind helium, whose charge-exchange lifetime is much longer. Recent composition measurements, however, seem to indicate that helium has only a secondary role, though O + (also long lived) may be important (Young, 1983, Section 4). Lyons and Williams (1981) have proposed that most of AB in a magnetic storm is derived not from the injection of fresh particles but by driving closer to Earth particles already trapped in the ring current.…”

Section: February 1980mentioning

confidence: 99%

Energetics of the magnetosphere

Stern

1984

Space Sci Rev

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Section: February 1980mentioning

confidence: 99%

Energetics of the magnetosphere

Stern

1984

Space Sci Rev

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“…Furthermore, the above mentioned studies of AMPTE/CCE observations were the first statistical studies of energy density in the near-Earth magnetotail with multi-species ion data extending into the higher energy range (>_20 keV/e). A large gap in multispecies ion measurements between 20 and 200 keV existed until the middle of the 1980s; this was considered critical in the effort to assess the makeup of magnetospheric populations (Young, 1983). Furthermore, the energy range between 20 and 200 keV was suggested (Williams, 1981) and later shown (Krimigis et al, 1985;Hamilton et al, 1988) to be the most important energy range during the main phase of geomagnetic storms, because the bulk of the ring current energy density is contained within this range.…”

Section: Introductionmentioning

confidence: 99%

Auroral Ionospheric Ion Feeding of the Inner Plasma Sheet during Substorms

Daglis

Axford²,

Livi³

et al. 1996

J. geomagn. geoelec

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During the last decade, satellite observations in the nightside magnetosphere have confirmed the presence of energetic (>20 keV) ionospheric-origin ions in the near-Earth magnetotail. Observations also imply that the feeding of the equatorial magnetosphere with ions from the high-latitude ionosphere can be very fast and intense at times. In the present paper we use observations from the Combined Release and Radiation Effects Satellite (CRRES) to investigate the characteristics of ion energy density variations. Multispecies studies of the energy density give important clues on the coupling of the different plasma sources and their participation in the substorm energization. The measurements, coming from the Magnetospheric Ion Composition Spectrometer (MICS), confirm previous results obtained from the AMPTE/CCE-CHEM spectrometer, with regard to the timing of the high-latitude ionosphere response to the equatorial magnetosphere disturbances. The energy density profile of the ionospheric-origin 0+ follows the intensity enhancements of the westward electrojet very closely in time, exhibiting a continuing increase, contrary to the behaviour of the other major ion species H+ and He++. This feature, which is consistent with statistical studies of AMPTE/CCE observations, points towards a fast activation of an extraction/acceleration mechanism which feeds the inner plasma sheet with ions of ionospheric origin during the substorm expansion.

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“…In refilling models without the initial pitch angle scattering, the superthermal ions produced by the plasma expansion are lost as they precipitate down into the conjugate ionospheres; their contribution to the refilling lasts for a brief time when they transit from one hemisphere to the other. However, satellite observations have clearly shown that the superthermal ion population is a regular feature of the flux tubes undergoing refilling [Young, 1983;Sojka et al, 1983]. We suggest that the wave-particle interactions studied in this paper make a significant contribution to the accumulation of the superthermal ion population in the flux tubes during refilling.…”

Section: Cross-scale Couplingmentioning

confidence: 61%

“…0148-0227/99/1999JA900341 $09.00 thermal ions, ranging from ion beams to trapped anisotropic ions and ion conics [e.g., see Young, 1983;Sojka et al, 1983]. Theoretical models of plasmaspheric refilling have shown persistence of counterstreaming ion beams in the equatorial regions over several hours before the Coulomb collisions become effective [Wilson et al, 1992].…”

Section: Paper Number 1999ja900341mentioning

confidence: 99%

Nonlinear features of electrostatic ion cyclotron instability driven by counterstreaming ion beams in equatorial outer plasmasphere

Singh¹,

Leung²

1999

J. Geophys. Res.

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Abstract. A commonly observed feature of the field-aligned flow of ions on closed geomagnetic field lines is that the pitch angle distributions are considerably broadened. Such pitch angle distributions facilitate in trapping ions and thus contribute to the process of plasmaspheric refilling. Since counterstreaming ion beams are a common feature of the early stage refilling as shown by models, we have investigated the role of ion-beam-driven instabilities in broadening the pitch angle distribution of the ion beams. The study is performed using a 2.5-dimensional particle-in-cell code. It is shown that for sufficiently fast ion beams as expected in the outer region of the plasmasphere, the ion cyclotron modes, which appear at frequencies less than the ion-cyclotron frequency •'•i in the rest frame of the nondrifting electrons, are the dominant unstable wave modes. In the early stage of the instability a nearly purely growing mode dominates, which efficiently mediates in transferring a part of the parallel drift energy into the perpendicular energy, significantly broadening the ion pitch angle distribution. The transfer abruptly saturates when d•(/q_p•f)-->0, where .In( ) is the Bessel function of an appropriate order n, kñ is the perpendicular wave number of the dominant mode, and p•f is the maximum value of the Larmor radius of the beam ions in anomalous cyclotron resonance with the wave. This behavior of the dominant mode in conjunction with the conservation of ion energy allows a method for including such wave-particle interaction effects in mesoscale models for the plasmaspheric refilling. The perpendicular acceleration of ions by this instability reduces the parallel drift only by a relatively small fraction, leaving the counterstreaming intact. However, the perpendicular acceleration produces a pitch angle distribution which is inducive for the trapping of the counterstreaming ions in the plasmaspheric flux tubes.

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Near‐equatorial magnetospheric particles from ∼1 eV to ∼1 MeV

Cited by 47 publications

References 253 publications

Energetics of the magnetosphere

Energetics of the magnetosphere

Auroral Ionospheric Ion Feeding of the Inner Plasma Sheet during Substorms

Nonlinear features of electrostatic ion cyclotron instability driven by counterstreaming ion beams in equatorial outer plasmasphere

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