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| Titel |
Resonant scattering of energetic electrons in the plasmasphere by monotonic whistler-mode waves artificially generated by ionospheric modification |
| VerfasserIn |
S. S. Chang, B. B. Ni, J. Bortnik, C. Zhou, Z. Y. Zhao, J. X. Li, X. D. Gu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 32, no. 5 ; Nr. 32, no. 5 (2014-05-21), S.507-518 |
| Datensatznummer |
250121058
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| Publikation (Nr.) |
 copernicus.org/angeo-32-507-2014.pdf |
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| Zusammenfassung |
| Modulated high-frequency (HF) heating of the ionosphere provides a feasible
means of artificially generating extremely low-frequency
(ELF)/very low-frequency (VLF) whistler waves, which can leak into the inner
magnetosphere and contribute to resonant interactions with high-energy
electrons in the plasmasphere. By ray tracing the magnetospheric propagation
of ELF/VLF emissions artificially generated at low-invariant latitudes, we
evaluate the relativistic electron resonant energies along the ray paths and
show that propagating artificial ELF/VLF waves can resonate with electrons
from ~ 100 keV to ~ 10 MeV. We further implement
test particle simulations to investigate the effects of resonant scattering
of energetic electrons due to triggered monotonic/single-frequency ELF/VLF
waves. The results indicate that within the period of a resonance timescale,
changes in electron pitch angle and kinetic energy are stochastic, and the
overall effect is cumulative, that is, the changes averaged over all test
electrons increase monotonically with time. The localized rates of wave-induced pitch-angle scattering and momentum diffusion in the plasmasphere
are analyzed in detail for artificially generated ELF/VLF whistlers with an
observable in situ amplitude of ~ 10 pT. While the local momentum
diffusion of relativistic electrons is small, with a rate of < 10−7 s−1, the local pitch-angle scattering can be intense near the
loss cone with a rate of ~ 10−4 s−1. Our
investigation further supports the feasibility of artificial triggering of
ELF/VLF whistler waves for removal of high-energy electrons at lower L
shells within the plasmasphere. Moreover, our test particle simulation
results show quantitatively good agreement with quasi-linear diffusion
coefficients, confirming the applicability of both methods to evaluate the
resonant diffusion effect of artificial generated ELF/VLF whistlers. |
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