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| Titel |
Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability |
| VerfasserIn |
C. Krafft, A. Volokitin |
| 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 ; 21, no. 7 ; Nr. 21, no. 7, S.1393-1403 |
| Datensatznummer |
250014650
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1393-2003.pdf |
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| Zusammenfassung |
Several in situ
measurements performed in the solar wind evidenced that solar type III radio
bursts were some-times associated with locally excited Langmuir waves,
high-energy electron fluxes and low-frequency electrostatic and electromagnetic
waves; moreover, in some cases, the simultaneous identification of energetic
electron fluxes, Langmuir and whistler waves was performed. This paper shows
how whistlers can be excited in the disturbed solar wind through the so-called
"fan instability" by interacting with energetic electrons at the
anomalous Doppler resonance. This instability process, which is driven by the
anisotropy in the energetic electron velocity distribution along the ambient
magnetic field, does not require any positive slope in the suprathermal
electron tail and thus can account for physical situations where plateaued
reduced electron velocity distributions were observed in solar wind plasmas in
association with Langmuir and whistler waves. Owing to linear calculations of
growth rates, we show that for disturbed solar wind conditions (that is, when
suprathermal particle fluxes propagate along the ambient magnetic field), the
fan instability can excite VLF waves (whistlers and lower hybrid waves) with
characteristics close to those observed in space experiments.
Key words. Space plasma physics
(waves and instabilities) – Radio Science (waves in plasma) – Solar
physics, astrophysics and astronomy (radio emissions) |
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