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Simultaneous Trapping of Electromagnetic Ion Cyclotron and Magnetosonic Waves by Background Plasmas
Author(s) -
Yuan Zhigang,
Yu Xiongdong,
Ouyang Zhihai,
Yao Fei,
Huang Shiyong,
Funsten H. O.
Publication year - 2019
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja026149
Subject(s) - physics , cyclotron , electromagnetic radiation , plasma , electron , atomic physics , ion , computational physics , ion acoustic wave , wave propagation , cyclotron radiation , optics , nuclear physics , quantum mechanics
Electromagnetic ion cyclotron waves and fast magnetosonic waves are found to be simultaneously modulated by background plasma density: both kinds of waves were observed in high plasma density regions but vanished in low‐density regions. Theoretical analysis based on Snell's law and linear growth theory has been utilized to investigate the physical mechanisms driving such modulation. It is suggested that the modulation of fast magnetosonic waves might be due to trapping by plasma density structures, which results from the conservation of the parameter Q during their propagation. Here Q = nr sin ψ , with n as the refractive index, r as the radial distance, and ψ as the wave azimuthal angle. As for electromagnetic ion cyclotron waves, the modulation might be owed to the ion composition difference between different plasma density regions. Our results indicate the alternative mechanism for the simultaneous appearance of electromagnetic ion cyclotron waves and fast magnetosonic waves (rather than wave excitations of both two wave emissions), which might take combined effects on the evolution of radiation belt electrons.