The Modulation of Plasma and Waves by Background Electron Density Irregularities in the Inner Magnetosphere

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Keywords
Abstract
The background cold electron density plays an important role in plasma and wave dynamics. Here, we investigate an event with clear modulation of the particle fluxes and wave intensities by background electron density irregularities based on Van Allen Probes observations. The energies at the peak fluxes of protons and Helium ions of 100 eV to several keV are well correlated with the total electron density variation. Intense electromagnetic ion cyclotron (EMIC) and magnetosonic (MS) waves are simultaneously observed in the high-density regions and disappear in low-density regions. Based on the linear theory of wave growth, the EMIC waves are generated by the ~10 keV protons, while most MS waves are generated by the positive gradient of proton phase space density at several hundred eV in the high-density regions. Our results indicate the importance of background plasma density structures in generation of plasma waves by unstable ion distributions.
Notes
Year of Publication
2020
Journal
Geophysical Research Letters
Volume
47
Number
Number of Pages
e2020GL088855
Date Published
07/2020
URL
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL088855
DOI
https://doi.org/10.1029/2020GL088855