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Narrowband Magnetosonic Waves Near the Lower Hybrid Resonance Frequency in the Inner Magnetosphere: Wave Properties and Excitation Conditions
Author(s) -
Ouyang Zhihai,
Yuan Zhigang,
Yu Xiongdong,
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 - 10.1029/2020ja028158
Subject(s) - physics , narrowband , plasmasphere , magnetosphere , resonance (particle physics) , excitation , excited state , van allen probes , computational physics , atomic physics , van allen radiation belt , optics , plasma , nuclear physics , quantum mechanics
In this study, the excitation of narrowband fast magnetosonic (MS) waves near the lower hybrid resonance frequency ( f LHR ) has been investigated with observations from Van Allen Probes mission and linear growth theory. A typical wave event is first examined to show that these waves can be excited through linear instabilities driven by partial shell distributions of protons. Then it is found that these narrowband MS waves from 188 wave events observed by the Van Allen Probe A between January 1, 2013 to December 31, 2015 have central frequencies around 0.7 f LHR with a bandwidth of 0.2 f LHR . In addition, these waves are observed mainly in the dayside and dusk sectors outside the plasmapause, which is different from previously reported results. Moreover, the simultaneously observed energetic protons during wave activities show that the ratios of the ring speed V r to the Alfvén speed V A mainly fall into the range of 0.8 < V r / V A < 1, and this preferred condition for excitations of narrowband MS waves near f LHR is also verified by a parameter analysis of calculating linear wave growth rates combined with wave observations.