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| Titel |
Density fluctuations measured by ISEE 1-2 in the Earth's magnetosheath and the resultant scattering of radio waves |
| VerfasserIn |
C. Lacombe, J.-L. Steinberg, C. C. Harvey, D. Hubert, A. Mangeney, M. Moncuquet |
| 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 ; 15, no. 4 ; Nr. 15, no. 4, S.387-396 |
| Datensatznummer |
250012724
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| Publikation (Nr.) |
 copernicus.org/angeo-15-387-1997.pdf |
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| Zusammenfassung |
| Radio waves undergo angular scattering when
they propagate through a plasma with fluctuating density. We show how the
angular scattering coefficient can be calculated as a function of the frequency
spectrum of the local density fluctuations. In the Earth's magnetosheath, the
ISEE 1-2 propagation experiment measured the spectral power of the density
fluctuations for periods in the range 300 to 1 s, which produce most of the
scattering. The resultant local angular scattering coefficient can then be
calculated for the first time with realistic density fluctuation spectra, which
are neither Gaussian nor power laws. We present results on the variation of the
local angular scattering coefficient during two crossings of the dayside
magnetosheath, from the quasi-perpendicular bow shock to the magnetopause. For a
radio wave at twice the local electron plasma frequency, the scattering
coefficient in the major part of the magnetosheath is b(2fp)
≃ 0.5 – 4 × 10–9 rad2/m. The scattering coefficient
is about ten times stronger in a thin sheet (0.1 to1RE) just
downstream of the shock ramp, and close to the magnetopause. |
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