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Effects of the Plasmapause on the Radial Propagation of Fast Magnetosonic Waves: An Analytical Approach
Author(s) -
Yu Xiongdong,
Yuan Zhigang,
Ouyang Zhihai,
Yao Fei
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028330
Subject(s) - plasmasphere , wkb approximation , ray tracing (physics) , physics , computational physics , wavelength , boundary layer , boundary value problem , wave propagation , magnetic field , quantum electrodynamics , classical mechanics , mechanics , optics , magnetosphere , quantum mechanics
In this study, analytical approximation is used to solve the wave equations near the plasmapause boundary layer in order to examine the validity of ray tracing approach for fast magnetosonic (MS) wave propagations, and then analytical solutions for electromagnetic fields of MS waves through the plasmapause boundary layer are provided for the first time. Both theoretical calculations from the analytical expressions and observations of Van Allen Probes have indicated that electric fields of MS waves decrease rapidly but magnetic fields increase rapidly when propagating across the plasmapause boundary layer from the outside. Considering effects of the plasmapause width and wave frequency, parameter analysis has shown that when the width of the plasmapause boundary layer is narrow in comparison with the wavelength of MS waves, a significant part of waves will be reflected. In these circumstances, the WKB approximation and then ray tracing method might become invalid, and analytical approach provided in this paper could be utilized to solve the wave equation.