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Results for “OUTER RADIATION BELT”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1965

On the origin of outer-belt protons. i.

Energy spectra variation with pitch angle and L of relatively stable 0.1- to 5-mev protons in outer radiation belt indicate external source

OUTER RADIATION BELT↗
NASA NTRS2006

The Role of Ring Current on Slot Region Penetration

During magnetic quiet times, the inner belt, slot region and the outer belt are well defined regions. However, during some major storms, outer belt particles penetrate inward and significantly fill the slot region. In some extreme events, the outer belt particles travel through the slot and create a new belt in the inner region that persists from months to years. In this paper, we examine the role of the ring current on this radiation belt penetration into the slot region. The storm-time intensification of the ring current produces strong magnetic depression in the inner magnetosphere. This perturbation and its fluctuation enhance the radial transport and diffusion of the outer radiation belt particles. We perform kinetic and test-particle calculations to quantitatively assess the effects of the ring current field on filling of the slot region. Simulation results during major storms will be presented and discussed.

Fok, Mei-Ching↗
NASA NTRS2007

Whistlers Observed Outside the Plasmasphere: Correlation to Plasmaspheric/Plasmapause Features and Implications for the Scattering of Radiation-Belt Electrons

Magnetospherically reflected, lightning-generated whistler waves are an important potential contributor to pitch-angle scattering loss processes of the electron radiation belts. While lightning-generated whistlers are a common feature at, and just inside, the plasmapause, they are infrequently observed outside the plasmasphere. As such, their potential contribution to outer radiation belt loss processes is more tenuous. Recently, Platino et al. [2005] has reported on whistlers observed outside the plasmasphere by Cluster. Here, we present correlative global observations of the plasmasphere, for the reported periods of Cluster-observed whistlers outside the plasmasphere, using IMAGE-EUV data. The intent of this study is to seek the underlying mechanisms that result in whistlers outside the plasmasphere and consequently the anticipated morphology and significance these waves may have on radiation belt dynamics.

Adrian, Mark L.↗
NASA NTRS2024

Comparative Observations of the Outer Belt Electron Fluxes and Precipitated Relativistic Electrons

Relativistic electron precipitation (REP) refers to the release of high‐energy electrons initially trapped in the outer radiation belt, which then precipitate into Earth's upper atmosphere, contributing significantly to the rapid depletion of radiation belt electron flux. This study presents a statistical analysis of REP observations collected by the Calorimetric Electron Telescope (CALET) experiment aboard the International Space Station from 2015 to the present day. Specifically, the analysis utilizes count rates acquired from the two top scintillators constituting the top charge detector, each sensitive to electrons with energies above 1.5 and 3.4 MeV, respectively. Analysis of CALET data reveals a previously unreported semi‐annual variation in the occurrence of REP events. REP periodicities resemble those observed for trapped electron fluxes in the outer belt. Furthermore, their amplitude follows the overall trend of solar wind high‐speed streams and the solar activity.

Sergio E. Vidal-Luengo↗
NASA NTRS1999

May 4, 1998 Storm: Observations of Energetic Ion Composition by POLAR

A major geomagnetic storm occurred at 5:00-12:05 UT on May 4, 1998. During this period, the magnetosphere was compressed and eroded; POLAR traveled in its outbound orbit from the equatorial radiation belt to the cusp and crossed the magnetopause into the magnetosheath. Two CEP-like (Cusp Energetic Particle) events with two to three orders of magnitudes enhancements of MeV ion fluxes were measured. The first event had a peak flux higher than that of the intense outer radiation belt in the equatorial plane. The shape of the measured energy spectra (in the unit of keV/e) were ion species dependent. For He+/He++ ratio at 18-269 keV/e, the difference between the radiation belt and the magnetosheath can be by a factor of as large as 62. In the magnetosheath, the 18-269 keV/e ion composition are variable, indicating a mass dependent acceleration process. These MeV ions may be energized by a mechanism in the cusp responsible for the CEP events previously reported.

Chen, Jiasheng↗
NASA NTRS1978

Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

Hovestadt, D.↗