FST Research Publications
2024 |
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EMIC Wave Energy Dissipation as a Source of O+ Conics and Warm Plasma Cloak in the Earth's Inner Magnetosphere
Konstantin V. Gamayunov, Hyomin Kim, Youra Shin Published: 11 May 2024, https://doi.org/10.1029/2023JA032399 Abstract: This study focuses on a specific source of the O+ conics and warm plasma cloak in the Earth's inner magnetosphere due to electromagnetic ion cyclotron (EMIC) wave energy dissipation. We analyze the EMIC wave event observed by Van Allen Probe-A in the early afternoon off equatorial magnetosphere on 18 November 2015, where the two dominant EMIC wave bands, He+-band and H+-band, were observed for ∼4 min. All the wave and plasma parameters, the DC magnetic field, and ion distributions needed for our analysis are taken from the Van Allen Probe-A observations during the event. The major results of our analysis are as follows. (a) The H+ and He+ heating by EMIC waves is negligible. (b) A strong heating of O+ by the wave energy dissipation around the third, fifth, and sixth harmonics of the O+ gyrofrequency is revealed, where the majority of energy dissipated goes into heating of O+ with the energies ≲100 eV and pitch angles ∼20°–90°. The estimated energy deposition rate is ∼0.1–3.4 eV/s per O+, totaling to the deposition of ∼20–800 eV per O+ during the event. (c) EMIC waves substantially contribute to the formation of O+ conics and warm plasma cloak by heating the upgoing low-energy ionospheric O+ because waves heat ions with the energies and pitch angles that are characteristic of conics and warm plasma cloak, and the energy deposition per O+ is comparable to those characteristic energies. |