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Poloidal Mode Wave‐Particle Interactions Inferred From Van Allen Probes and CARISMA Ground‐Based Observations
Author(s) -
Wang C.,
Rankin R.,
Wang Y.,
Zong Q.G.,
Zhou X.,
Takahashi K.,
Marchand R.,
Degeling A. W.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2017ja025123
Subject(s) - physics , flux (metallurgy) , spacecraft , ion , computational physics , resonance (particle physics) , equator , pitch angle , mode (computer interface) , atomic physics , energy flux , geophysics , latitude , materials science , astronomy , quantum mechanics , computer science , metallurgy , operating system
Ultralow‐frequency wave and test particle models are used to investigate the pitch angle and energy dependence of ion differential fluxes measured by the Van Allen Probes spacecraft on 6 October 2012. Analysis of the satellite data reveals modulations in differential flux resulting from drift resonance between H + ions and fundamental mode poloidal Alfvén waves detected near the magnetic equator at L ∼ 5.7. Results obtained from simulations reproduce important features of the observations, including a substantial enhancement of the differential flux between ∼20 and 40° pitch angle for ion energies between ∼90 and 220 keV and an absence of flux modulations at 90°. The numerical results confirm predictions of drift‐bounce resonance theory and show good quantitative agreement with observations of modulations in differential flux produced by ultralow‐frequency waves.