Outer Zone Protons

Davis, Leverett; Williamson, James M.

doi:10.1007/978-94-010-3553-8_17

Cited by 33 publications

(3 citation statements)

References 9 publications

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“…Increases in the proton population of the Van Allen belts during magnetic storms have been observed and described in literature [Mcllwain, 1965;Davis, 1965;Davis and Williamson, 1966;and Vernov et al, 1965].…”

Section: Introductionmentioning

confidence: 97%

Proton events in the magnetosphere associated with magnetic bays

Konradi¹

1967

J. Geophys. Res.

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A series of 13 sudden increases in the proton flux was observed at L > 8 on the subsolar side of the magnetosphere during August, September, and October 1961. These increases are strongly correlated with the appearance of negative magnetic bays in the auroral zone. The increases exhibit proton intensities of J (>100 kev) ≲ 106 p/cm² sec ster. The particle intensity rise time is of the order of 10 minutes. The protons have strongly peaked energy distributions, and the peak energy decreases with time during a period of about 1 hour from about 300 key to 100 key. The events are interpreted as protons drifting in the earth's magnetosphere after being injected into it on the night side.

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Section: Introductionmentioning

confidence: 97%

Proton events in the magnetosphere associated with magnetic bays

Konradi¹

1967

J. Geophys. Res.

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“…Early observations at energies >100 keV [ Davis and Williamson , , ] and at lower energies [ Frank , , , ] established the understanding that these magnetospheric ions were associated with the development of the ring current. Later studies determined that the relevant ring current population associated with geomagnetic disturbances during storms existed at energies between ∼20 and 300 keV [ Smith and Hoffman , ; Berko et al , ; Williams and Lyons , ; Williams , ].…”

Section: Introductionmentioning

confidence: 99%

Dominance of high‐energy (>150 keV) heavy ion intensities in Earth's middle to outer magnetosphere

et al. 2017

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Previous observations have driven the prevailing assumption in the field that energetic ions measured by an instrument using a bare solid state detector (SSD) are predominantly protons. However, new near‐equatorial energetic particle observations obtained between 7 and 12 RE during Phase 1 of the Magnetospheric Multiscale mission challenge the validity of this assumption. In particular, measurements by the Energetic Ion Spectrometer (EIS) instruments have revealed that the intensities of heavy ion species (specifically oxygen and helium) dominate those of protons at energies ≳150–220 keV in the middle to outer (>7 RE) magnetosphere. Given that relative composition measurements can drift as sensors degrade in gain, quality cross‐calibration agreement between EIS observations and those from the SSD‐based Fly's Eye Energetic Particle Spectrometer (FEEPS) sensors provides critical support to the veracity of the measurement. Similar observations from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments aboard the Van Allen Probes spacecraft extend the ion composition measurements into the middle magnetosphere and reveal a strongly proton‐dominated environment at L≲6 but decreasing proton intensities at L≳6. It is concluded that the intensity dominance of the heavy ions at higher energies (>150 keV) arises from the existence of significant populations of multiply‐charged heavy ions, presumably of solar wind origin.

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“…Although the outer proton radiation belt has been observed by spacecraft instrumentation for five decades [e.g., Davis and Williamson , , ; Yershkovitch et al , ; Stevens et al , ; Spjeldvik , ; Fritz and Spjeldvik , ; Sheldon , ; Green et al , ; Lazutin et al , , ; Tverskaya et al , ; Forster et al , ], much less is known about its properties and dynamics than is known about the outer electron radiation belt. Modeling efforts for the outer proton radiation belt in those five decades [e.g., Nakada and Mead , ; Spjeldvik , ; Beutier et al , ; Bourdarie et al , ; Boscher et al , ; Vacaresse et al , ; Panasyuk , ; Smolin , , ] have been much less sophisticated than the modeling efforts for the outer electron radiation belt.…”

Section: Introductionmentioning

confidence: 99%

The proton and electron radiation belts at geosynchronous orbit: Statistics and behavior during high‐speed stream‐driven storms

Borovsky

Cayton²,

Denton

et al. 2016

JGR Space Physics

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The outer proton radiation belt (OPRB) and outer electron radiation belt (OERB) at geosynchronous orbit are investigated using a reanalysis of the LANL CPA (Charged Particle Analyzer) 8‐satellite 2‐solar cycle energetic particle data set from 1976 to 1995. Statistics of the OPRB and the OERB are calculated, including local time and solar cycle trends. The number density of the OPRB is about 10 times higher than the OERB, but the 1 MeV proton flux is about 1000 times less than the 1 MeV electron flux because the proton energy spectrum is softer than the electron spectrum. Using a collection of 94 high‐speed stream‐driven storms in 1976–1995, the storm time evolutions of the OPRB and OERB are studied via superposed epoch analysis. The evolution of the OERB shows the familiar sequence (1) prestorm decay of density and flux, (2) early‐storm dropout of density and flux, (3) sudden recovery of density, and (4) steady storm time heating to high fluxes. The evolution of the OPRB shows a sudden enhancement of density and flux early in the storm. The absence of a proton dropout when there is an electron dropout is noted. The sudden recovery of the density of the OERB and the sudden density enhancement of the OPRB are both associated with the occurrence of a substorm during the early stage of the storm when the superdense plasma sheet produces a “strong stretching phase” of the storm. These storm time substorms are seen to inject electrons to 1 MeV and protons to beyond 1 MeV into geosynchronous orbit, directly producing a suddenly enhanced radiation belt population.

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Outer Zone Protons

Cited by 33 publications

References 9 publications

Proton events in the magnetosphere associated with magnetic bays

Proton events in the magnetosphere associated with magnetic bays

Dominance of high‐energy (>150 keV) heavy ion intensities in Earth's middle to outer magnetosphere

The proton and electron radiation belts at geosynchronous orbit: Statistics and behavior during high‐speed stream‐driven storms

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