Formation of the Low-Energy “Finger” Ion Spectral Structure Near the Inner Edge of the Plasma Sheet

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Abstract
We present a case study of the H+, He+, and O+ low-energy “finger” structure observed by the Van Allen Probe A Helium, Oxygen, Proton, and Electron (HOPE) spectrometer on 26 October 2016. This structure, whose characteristic energy is from approximately tens of eV to a few keV, looks like a “finger” that is rich in O+ and He+, faint in H+ on an energy-time spectrogram. By using the Space Weather Modeling Framework (SWMF) and Weimer05 electric fields, combined with a dipole or more self-consistent magnetohydrodynamic (MHD) magnetic field, backward tracing of O+ reveals that the structure is formed by ions with a long drift time from the plasma sheet during the magnetic storm main phase to the inner region with trajectories dominated by eastward drift motion, and the formation depends on the convection electric field model. The heavy ion dominance of the feature is explained by charge exchange losses along the long slow drift paths.
Notes
Year of Publication
2020
Journal
Geophysical Research Letters
Volume
47
Number
Number of Pages
e2020GL089875
Date Published
11/2020
URL
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089875
DOI
https://doi.org/10.1029/2020GL089875