Detached plasma regions in the magnetosphere

Chappell, C. R.

doi:10.1029/ja079i013p01861

Cited by 273 publications

(211 citation statements)

References 15 publications

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“…However, 10 min averaged data processed from 1 min averaged data are analyzed when we discuss convections. Chappell [1974], it corresponds to n > 1.9 cm -3 at L = 10, which is close to the present criterion of n > 2 cm -a for the Geotail data analysisß…”

Section: Energy-time (E-t) Diagrams Processed From the Par-supporting

confidence: 89%

“…On the other hand, the density observed at the geosynchronous orbit in the same MLT is less than 5 cm -a. It is a similar structure to the detached plasma observed by OGO 5 [Chappell, 1974], such that there is a region with a minimum value of density between the region with CDP in the outer magnetosphere and main body of the plasmasphere inside the geosynchronous orbit. After 1500 MLT the density observed by Geotail decreases.…”

Section: Case Studiessupporting

confidence: 57%

“…Such a case happens when the plasmasphere has been recently eroded owing to a prior period of enhanced activity and the outer plasmasphere has not had enough time of plasma supply. Another problem with the above interpretation is that it is hard to explain the following configurations that were clarified previously: the eddy flows [Carpenter et al, 1993] and detachment [Chappell, 1974] of the plasmaspheric material. Although it is not clear whether we have observed such configurations, we should have a consistent model with previous and current observations in the future.…”

Section: Discussionmentioning

confidence: 96%

“…It is well known that a significant amount of cold plasma is at times observed in the outer magnetosphere [Chappell, 1974] …”

Section: Introductionmentioning

confidence: 99%

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Cold dense plasma in the outer magnetosphere

Matsui¹,

Mukai²,

Ohtani³

et al. 1999

J. Geophys. Res.

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Abstract. Cold dense plasma (CDP) with energies less than 32 eV in the outer magnetosphere, L •0 10, is reported using data obtained by Geotail. We have found unexpectedly recurrent CDP in afternoon magnetic local times. CDP is often accompanied by westward flows, indicating that the regions with CDP are located outside the corotation region and the plasma is presumably convected toward the magnetopause. CDP is observed in the cases of both small and moderate geomagnetic activity. We have calculated the location of the stagnation point as a function of cross-tail potential by using a Volland-Stern-type [Volland, 1973;Stern, 1975] convection model. Stagnation point locations are variable even if the cross-tail potential or geomagnetic activity is small, which could lead to a high rate of the observation of plasmaspheric material at the Geotail orbit. However, part of the cold plasma is directly supplied by the ionosphere without passing through the plasmasphere. The number of supplied particles could be larger on the drift orbits close to the stagnation points. Finally, an average quantity of cold plasma flowing through the Geotail orbit with quasi-stable westward convection is estimated to be 3.6 x 10 25 ions/s with a standard deviation of 3.7 x 10 25 ions/s, as compared to 9.4-14 x 10 2s ions/s for the polar wind toward the plasma sheet.

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Section: Energy-time (E-t) Diagrams Processed From the Par-supporting

confidence: 89%

Section: Case Studiessupporting

confidence: 57%

Section: Discussionmentioning

confidence: 96%

“…It is well known that a significant amount of cold plasma is at times observed in the outer magnetosphere [Chappell, 1974] …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cold dense plasma in the outer magnetosphere

Matsui¹,

Mukai²,

Ohtani³

et al. 1999

J. Geophys. Res.

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“…Inward convection of ring current ions and electrons provides a source of free energy for the excitation of both electromagnetic ion cyclotron (EMIC) waves [Kozyra et al, 1997] and whistler waves. Furthermore, the location of the plasmapause also significantly alters during storms [Chappell, 1972[Chappell, , 1974. Electron fluxes throughout the outer radiation belt significantly change during a magnetic storm [e.g., Baker et al, 1986Baker et al, , 1994.…”

Section: Discussionmentioning

confidence: 99%

SAMPEX observations of precipitation bursts in the outer radiation belt

Nakamura¹,

Isowa²,

Kamide³

et al. 2000

J. Geophys. Res.

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Abstract. The occurrence frequency of precipitation bursts of > 1 MeV electrons in the outer radiation belt is examined using data from the SAMPEX satellite. Electron burst characteristics shown in this paper include the dependence of the precipitation on magnetic local time, radial distance and geomagnetic activity. Precipitation bursts with timescales < 1 s, i.e., microbursts, are studied in detail, including their dependence on the phases of geomagnetic storms. It is found that precipitation bursts occur typically in the region between L = 4 and L = 6. Microbursts tend to occur at L lower than the bursts with timescales of several tens of seconds. The number of observed microbursts significantly increases during storms, appearing mainly in the morning sector early in the recovery phase of storms. These findings suggest that the microbursts may be due to interactions with electron whistler waves, which take place near the dawnside plasmapause in the density irregularities that are perhaps created in the "recovering" plasmasphere. The prevalence of bursty precipitation indicates that this enhanced loss component of the relativistic electron flux should be taken into account in any quantitative model of relativistic electron acceleration processes.

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On the presence and properties of cold ions near Earth's equatorial magnetosphere

2014

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Plasma flows related to magnetospheric convection or ULF waves often increase cold ions' kinetic energy sufficiently above the spacecraft potential energy so that these ions can be detected by charged particle instrumentation. Other detection methods also reveal the presence of cold ions even in the absence of flows. By applying such methods to complementary data sets obtained from particle, electric field, and magnetic field measurements by the multiple Time History of Events and Macroscale Interactions during Substorms spacecraft, we study the occurrence rates of cold ions and properties-composition, densities, and temperatures-of the dominant species (H + , He + , and O + ) near the equatorial magnetosphere. As plasma flows occur at all magnetic local time (MLT) sectors, predominantly outside the plasmasphere, they enable studies of cold ion occurrence and properties as functions of geocentric distance (up to 13 R E ) and MLT. Of the dominant cold ions, protons are most abundant on the dayside and coldest almost everywhere. By comparison, the heavier ions show evidence of larger abundance on the nightside and higher temperatures at most locations: median n He+ /n H+ is ≤0.1 in the afternoon, ≥1.0 on the nightside, and near 0.5 at dawn; median n O+ /n H+ exceeds 1 throughout the nightside and around dawn at smaller geocentric distances but varies from 0.0 to 0.1 in the afternoon; and T O+ > T He+ everywhere. By isolating the convective particle drift component of measured ion flows, we deduce that nightside/dawn/prenoon cold ions are components of the warm plasma cloak while cold ions near noon/afternoon are likely of mixed origin, including nightside/cusp outflow, plasmaspheric plumes, and the solar wind.

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Detached plasma regions in the magnetosphere

Cited by 273 publications

References 15 publications

Cold dense plasma in the outer magnetosphere

Cold dense plasma in the outer magnetosphere

SAMPEX observations of precipitation bursts in the outer radiation belt

On the presence and properties of cold ions near Earth's equatorial magnetosphere

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