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In situ evidence of the modification of the parallel propagation of EMIC waves by heated He + ions
Author(s) -
Yuan Zhigang,
Yu Xiongdong,
Wang Dedong,
Huang Shiyong,
Li Haimeng,
Yu Tao,
Qiao Zheng,
Wygant John R.,
Funsten Herbert O.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022573
Subject(s) - emic and etic , ion , plasmasphere , dispersion relation , physics , cyclotron , atomic physics , plasma , computational physics , magnetosphere , nuclear physics , optics , quantum mechanics , sociology , anthropology
With observations of the Van Allen Probe B, we report in situ evidence of the modification of the parallel propagating electromagnetic ion cyclotron (EMIC) waves by heated He + ions. In the outer boundary of the plasmasphere, accompanied with the He + ion heating, the frequency bands of H + and He + for EMIC waves merged into each other, leading to the disappearance of a usual stop band between the gyrofrequency of He + ions (Ω He+ ) and the H + cutoff frequency ( ω H+co ) in the cold plasma. Moreover, the dispersion relation for EMIC waves theoretically calculated with the observed plasma parameters also demonstrates that EMIC waves can indeed parallel propagate across Ω He+ . Therefore, the paper provides an in situ evidence of the modification of the parallel propagation of EMIC waves by heated He + ions.