Journal article
The Impact of Plasma Density Gradients on Lower Band Chorus Wave Propagation
Geophysical research letters, Vol.52(6), e2024GL113258
03/28/2025
DOI: 10.1029/2024GL113258
Appears in UI Libraries Support Open Access
Abstract
Plasma density gradients, such as those that occur on plasmaspheric plume boundaries, have been shown to increase the obliquity of lower band chorus. Here, for the first time, this relationship is investigated more generally by considering the wave normal angle, , as a function of the magnitude of all observed density gradients. Both case studies, and a statistical analysis, reveal a direct correspondence between the magnitude of density gradients and wave obliquity, with increasing near stronger density gradients. Wave propagation is also investigated as a function of local plasma density, revealing that chorus is more often oblique when observed in lower density mediums, and more field‐aligned in higher density regions. This result highlights the importance of retaining the intrinsic physical coupling between wave propagation properties and the cold plasma density, since both parameters strongly influence the calculation of the diffusion coefficients used to quantify wave‐particle interactions in the inner‐magnetosphere.
Much like a prism refracts light, variations in the density of magnetospheric plasma impact the propagation of electromagnetic waves. This study investigates the relationship between chorus wave propagation and both the local plasma density, and gradients in the plasma density, for the first time. The propagation direction of chorus waves is shown to directly correspond to the local plasma density, as well as to the magnitude of density gradients that occur in the vicinity. Chorus waves can drive rapid acceleration of the Van Allen radiation belts up to relativistic energies, with calculations to quantify these wave‐particle interactions strongly influenced by both the plasma density and the propagation direction of the wave. As such, this result demonstrates that retaining the fundamental physical coupling between wave properties and the plasma density may be an important and worthwhile step toward accurate modeling and forecasting of the radiation belts.
Wave normal angle of chorus is investigated as a function of both the local plasma density, and plasma density gradients, for the first time Chorus wave obliquity is shown to directly correspond to both local plasma density, and the magnitude of density gradients in the vicinity Results highlight the importance of retaining the intrinsic physical coupling between wave propagation properties and the plasma density
Details
- Title: Subtitle
- The Impact of Plasma Density Gradients on Lower Band Chorus Wave Propagation
- Creators
- D. P. Hartley - University of IowaL. Chen - The University of Texas at DallasW. Gu - The University of Texas at DallasI. W. Christopher - University of IowaO. Santolik - Charles University
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.52(6), e2024GL113258
- Publisher
- Wiley
- DOI
- 10.1029/2024GL113258
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Grant note
- National Aeronautics and Space AdministrationNASA: 80NSSC24K0263 AFOSR: FA9550-23-1-0568 European Union's Horizon Europe programme: 101081772-FARBES Czech MEYS Interexcellence II programme: LUAUS23152
DPH, LC, and WG acknowledge that this material is based upon work supported by the National Aeronautics and Space Administration under Grant 80NSSC20K1324 issued through the Heliophysics Supporting Research Program. DPH and IWC acknowledge NASA Grant 80NSSC21K0519. DPH acknowledges NSF-GEM Grants 2040708 and 2350235. WG and LC acknowledge the support of NASA Grant 80NSSC24K0263 and the AFOSR Grant of FA9550-23-1-0568. OS acknowledges funding from the European Union's Horizon Europe programme under Grant 101081772-FARBES and from the Czech MEYS Interexcellence II programme through project LUAUS23152.
- Language
- English
- Date published
- 03/28/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984801843002771
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