A new, temporarily confined population in the polar cap during the August 27, 1996 geomagnetic field distortion period

On August 27, 1996, a two-hour energetic heavy ion event (∼1 MeV) was detected at 8:25 UT at apogee (∼9 Re and an invariant latitude of ∼80°), by the Charge and Mass Magnetospheric Ion Composition Experiment onboard POLAR. The event, with a maximum spin averaged peak flux of ∼150 particles/(cm²-sr-s-MeV), showed three local peaks corresponding to three localized regions; the ion pitch angle distributions in the three regions were different from an isotropic distribution and different from each other. No comparable flux was observed by the WIND spacecraft. The appearance of lower energy He++ and O \u3e +2 during the event period indicates a solar source for these particles. From region 1 to 2 to 3, the helium energy spectra softened. A distorted magnetic field with three local minima corresponding to the three He peak fluxes was also observed by POLAR. A possible explanation is that the energetic He ions were energized from lower energy helium by a local acceleration mechanism that preferred smaller rigidity ions in the high altitude polar cusp region

Cusp energetic particle events: Implications for a major acceleration region of the magnetosphere

The Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) on board the Polar spacecraft observed 75 energetic particle events in 1996 while the satellite was at apogee. All of these events were associated with a decrease in the magnitude of the local magnetic field measured by the Magnetic Field Experiment (MFE) on Polar. These new events showed several unusual features: (1) They were detected in the dayside polar cusp near the apogee of Polar with about 79% of the total events in the afternoonside and 21% in the morningside; (2) an individual event could last for hours; (3) the measured helium ion had energies up to and many times in excess of 2.4 MeV; (4) the intensity of 1–200 KeV/e helium was anticorrelated with the magnitude of the local geomagnetic field but correlated with the turbulent magnetic energy density; (5) the events were associated with an enhancement of the low-frequency magnetic noise, the spectrum of which typically extends from a few hertz to a few hundreds of hertz as measured by the Plasma Wave Instrument (PWI) on Polar; and (6) a seasonal variation was found for the occurrence rate of the events with a maximum in September. These characterized a new phenomenon which we are calling cusp energetic particle (CEP) events. The observed high charge state of helium and oxygen ions in the CEP events indicates a solar source for these particles. Furthermore, the measured 0.52–1.15 MeV helium flux was proportional to the difference between the maximum and the minimum magnetic field in the event. A possible explanation is that the energetic helium ions are energized from lower energy helium by a local acceleration mechanism associated with the high-altitude dayside cusp. These observations represent a potential discovery of a major acceleration region of the magnetosphere

Proceedings of the Air Force Geophysics Laboratory Workshop on the Earth's Radiation Belts : Jan. 26-27, 1981 /

A two-day workshop on the earth's radiation belts was held on 26-27 January 1981 at the Air Force Geophysics Laboratory. The workshop reviewed the present state of knowledge of the radiation belts and the effects of energetic particles on microelectronic systems. From this perspective it is possible to define the instrumentation requirements of future missions into the radiation belts. Proceedings of the workshop include: (1) reports on a tutorial session concerning the present level of understanding of radiation belt measurements, dynamics, wave-particle interactions, and their effects on microelectronic elements, (2) specifications of the state-of-the art instrumentation required to measure energetic particles, cold plasmas, magnetic fields, and waves, (3) overviews of existing statistical, numerical, and analytical models of the radiation belts, and (4) summaries of the sessions presented at the end of the workshop by the various session chairmen.Workshop sponsored by the Air Force Geophysics Laboratory, Air Force Systems Command, United States Air Force, Hanscom AFB, Massachusetts.Space Physics Division Project 7601.ADA113959 (from http://www.dtic.mil)."21 October 1981."Includes bibliographical references.A Summary Review of the Radiation Belt Workshop. (p. 279).Summary and Comparison of Radiation Beld Models, by Stanley M. Kaye. (p. 271).Modelling of Magnetically Trapped Radiation in the Inner Magnetosphere of the Earth, by Walther N. Spjeldvik. (p. 245).Magnetic Fields, Low Energy Plasma, and Wave Measurements in the Radiation Belts, by WIlliam J. Burke and David T. Young. (p. 209).State of the Art of Energetic Particle Measurements in the Earth's Magnetosphere, by Walther N. Spjeldvik, (p. 125).Radiation Effects on Electronic Systems, by Peter J. McNulty. (p. 99).The Role of Waves and Cold Plasma in the Dynamics of the Earth's Radiation Belts, by Delia E. Donatelli. (p. 69).A Theorist's View of the Earth's Radiation Belts, by Michael Heinemann. (p. 47).An Overview of Radiation Belt Dynamics, by William J. Burke. (p. 9).A two-day workshop on the earth's radiation belts was held on 26-27 January 1981 at the Air Force Geophysics Laboratory. The workshop reviewed the present state of knowledge of the radiation belts and the effects of energetic particles on microelectronic systems. From this perspective it is possible to define the instrumentation requirements of future missions into the radiation belts. Proceedings of the workshop include: (1) reports on a tutorial session concerning the present level of understanding of radiation belt measurements, dynamics, wave-particle interactions, and their effects on microelectronic elements, (2) specifications of the state-of-the art instrumentation required to measure energetic particles, cold plasmas, magnetic fields, and waves, (3) overviews of existing statistical, numerical, and analytical models of the radiation belts, and (4) summaries of the sessions presented at the end of the workshop by the various session chairmen.Mode of access: Internet

The earth's radiation belts /

This report develops radiation belt transport theory from physical principles and compares the results with experimental data. It also provides an easy reference to the present empirical radiation flux models with some simple application techniques given. Specialized topics include shell-splitting, effects of wave-particle interactions, the ring current, geosynchronous environment, nuclear detonations and radiation effects. Heavy ions are specifically high-lighted as a significant component of the radiation belts.Space Physics Division Project 7601."20 September 1983."Distributed to depository libraries in microfiche.Cover title.Includes bibliographical references.Scientific. Interim.This report develops radiation belt transport theory from physical principles and compares the results with experimental data. It also provides an easy reference to the present empirical radiation flux models with some simple application techniques given. Specialized topics include shell-splitting, effects of wave-particle interactions, the ring current, geosynchronous environment, nuclear detonations and radiation effects. Heavy ions are specifically high-lighted as a significant component of the radiation belts.Mode of access: Internet