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Relativistic Electron Acceleration and Decay Time Scales in the Inner and Outer Radiation Belts: SAMPEX

Baker, D. N. and Blake, J. B. and Callis, L. B. and Cummings, J. R. and Hovestadt, D. and Kanekal, S. G. and Klecker, B. and Mewaldt, R. A. and Zwickl, R. D. (1994) Relativistic Electron Acceleration and Decay Time Scales in the Inner and Outer Radiation Belts: SAMPEX. Geophysical Research Letters, 21 (6). pp. 409-412. ISSN 0094-8276. doi:10.1029/93GL03532.

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High-energy electrons have been measured systematically in a low-altitude (520 × 675 km), nearly polar (inclination = 82°) orbit by sensitive instruments onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX). Count rate channels with electron energy thresholds ranging from 0.4 MeV to 3.5 MeV in three different instruments have been used to examine relativistic electron variations as a function of L-shell parameter and time. A long run of essentially continuous data (July 1992–July 1993) shows substantial acceleration of energetic electrons throughout much of the magnetosphere on rapid time scales. This acceleration appears to be due to solar wind velocity enhancements and is surprisingly large in that the radiation belt “slot” region often is filled temporarily and electron fluxes are strongly enhanced even at very low L-values (L ∼ 2). A superposed epoch analysis shows that electron fluxes rise rapidly for 2.5 ≲ L ≲ 5. These increases occur on a time scale of order 1–2 days and are most abrupt for L-values near 3. The temporal decay rate of the fluxes is dependent on energy and L-value and may be described by J = Ke-t/to with to ≈ 5–10 days. Thus, these results suggest that the Earth's magnetosphere is a cosmic electron accelerator of substantial strength and efficiency.

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Mewaldt, R. A.0000-0003-2178-9111
Additional Information:Copyright 1994 by the American Geophysical Union. (Received October 21, 1993; accepted November 30, 1993.) We thank the many individuals who have contributed so extensively to the success of SAMPEX. We especially thank G. Mason and D. Hamilton at the University of Maryland, E. Stone and R. Selesnick at Caltech, and R. Boughner at Langley Research Center for major contributions to this research. We also thank S. Gussenhoven of Phillips Laboratory for CRRES data plots.
Group:Space Radiation Laboratory
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Space Radiation Laboratory1995-03
Issue or Number:6
Record Number:CaltechAUTHORS:20140612-100420272
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46235
Deposited By: Deborah Miles
Deposited On:12 Jun 2014 23:23
Last Modified:10 Nov 2021 17:22

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