Journal article
Investigation of Mass-/Charge-Dependent Escape of Energetic Ions Across the Magnetopauses of Earth and Jupiter
Journal of geophysical research. Space physics, Vol.124(7), pp.5539-5567
07/2019
DOI: 10.1029/2019JA026626
Abstract
We present a continuing investigation of mass-/charge-dependent interactions between energetic ions (greater than tens of kiloelectron volts) and planetary magnetopauses and of the escape of the ions across the boundary. Previous studies at Earth using Magnetospheric Multiscale mission data are refined and advanced showing profound behavior differences between light (H, He) and singly charged heavy ions (O+). We highlight a distinctive feature of oxygen ions: an angular distribution bifurcation providing clear indication of entrainment along the magnetopause in Speiser-like orbits during relatively stable magnetic conditions. This signature, interpreted using a simple kinetic model, suggests that these ions tend to be carried substantial distances along the boundary (even with boundary-normal magnetic fields) in a fashion that impedes their full dayside escape. While large fluctuations and waves can likely sometimes disrupt the observed ordering, the following picture emerges. Energetic particles with gyroradii much smaller than the magnetopause thickness (e.g., electrons and absent boundary-normal magnetic fields) and ions with gyroradii much larger than the thickness (e.g., O+) are impeded from fully escaping across the boundary. However, energetic ions with intermediate-sized gyroradii commensurate with the thickness (e.g., H+, He++, and O6+) can be effectively scattered within the boundary causing them to escape much more readily, with and without boundary-normal fields. This picture is supported by observations from the Juno spacecraft at the near-dawn meridian side of Jupiter's magnetopause. There it is observed that energetic electrons and heavy ions are more strongly contained by the magnetopause than are the energetic protons and helium ions.
Details
- Title: Subtitle
- Investigation of Mass-/Charge-Dependent Escape of Energetic Ions Across the Magnetopauses of Earth and Jupiter
- Creators
- B. H. Mauk - Johns Hopkins University Applied Physics LaboratoryI. J. Cohen - Johns Hopkins University Applied Physics LaboratoryD. K. Haggerty - Johns Hopkins University Applied Physics LaboratoryG. B. Hospodarsky - University of IowaJ. E. P. Connerney - Goddard Space Flight CenterB. J. Anderson - Johns Hopkins University Applied Physics LaboratoryF. Bagenal - Laboratory for Atmospheric and Space PhysicsR. W. Ebert - Southwest Research InstituteS. J. Bolton - Southwest Research InstituteJ. L. Burch - Southwest Research InstituteS. M. Levin - Jet Propulsion LaboratoryR. B. Torbert - Southwest Research InstituteS. K. Vines - Johns Hopkins University Applied Physics LaboratoryJ. H. Westlake - Johns Hopkins University Applied Physics Laboratory
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(7), pp.5539-5567
- DOI
- 10.1029/2019JA026626
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Publisher
- Amer Geophysical Union
- Number of pages
- 29
- Grant note
- NASA's Solar Terrestrial Probes program via subcontract with the Southwest Research Institute NASA's New Frontiers program via subcontract with the Southwest Research Institute
- Language
- English
- Date published
- 07/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455557702771
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