Abstract
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 (ΩHe+) and the H+ cutoff frequency (ωH+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 ΩHe+. Therefore, the paper provides an in situ evidence of the modification of the parallel propagation of EMIC waves by heated He+ ions.
Original language | English (US) |
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Pages (from-to) | 6711-6717 |
Number of pages | 7 |
Journal | Journal of Geophysical Research: Space Physics |
Volume | 121 |
Issue number | 7 |
DOIs | |
State | Published - Jul 1 2016 |
Bibliographical note
Publisher Copyright:©2016. American Geophysical Union. All Rights Reserved.
Keywords
- EMIC waves
- He ion heating
- Van Allen Probes
- ring current ions
- stop band