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A Statistical Test of the Relationship Between Chorus Wave Activation and Anisotropy of Electron Phase Space Density
A Statistical Test of the Relationship Between Chorus Wave Activation and Anisotropy of Electron Phase Space Density
- Source :
- Journal of Astronomy and Space Sciences, Vol 31, Iss 4, Pp 295-301 (2014)
- Publication Year :
- 2014
- Publisher :
- The Korean Space Science Society, 2014.
-
Abstract
- Whistler mode chorus wave is considered to play a critical role in accelerating and precipitating the electrons in the outer radiation belt. In this paper we test a conventional scenario of triggering chorus using THEMIS satellite observations of waves and particles. Specifically, we test if the chorus onset is consistent with development of anisotropy in the electron phase space density (PSD). After analyzing electron PSD for 73 chorus events, we find that, for ~80 % of them, their onsets are indeed associated with development of the positive anisotropy in PSD where the pitch angle distribution of electron velocity peaks at 90 degrees. This PSD anisotropy is prominent mainly at the electron energy range of ≤ ~20 keV. Interestingly, we further find that there is sometimes a time delay among energies in the increases of the anisotropy: A development of the positive anisotropy occurs earlier by several minutes for lower energy than for an adjacent higher energy.
- Subjects :
- whistler chorus
radiation belt electrons
wave-particle interaction
Astronomy
QB1-991
Subjects
Details
- Language :
- English
- ISSN :
- 20935587 and 20931409
- Volume :
- 31
- Issue :
- 4
- Database :
- Directory of Open Access Journals
- Journal :
- Journal of Astronomy and Space Sciences
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.5f7562e1527d4b5abfa0aadcd15eaa1d
- Document Type :
- article
- Full Text :
- https://doi.org/10.5140/JASS.2014.31.4.295