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Author
Bowen, Trevor A.Mallet, Alfred
Huang, Jia
Klein, Kristopher G.
Malaspina, David M.
Stevens, Michael
Bale, Stuart D.
Bonnell, J. W.
Case, Anthony W.
Chandran, Benjamin D. G.
Chaston, C. C.
Chen, Christopher H. K.
Dudok de Wit, Thierry
Goetz, Keith
Harvey, Peter R.
Howes, Gregory G.
Kasper, J. C.
Korreck, Kelly E.
Larson, Davin
Livi, Roberto
MacDowall, Robert J.
McManus, Michael D.
Pulupa, Marc
Verniero, J. L.
Whittlesey, Phyllis
Affiliation
Univ ArizonaIssue Date
2020-02-06
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IOP PUBLISHING LTDCitation
Bowen, T. A., Mallet, A., Huang, J., Klein, K. G., Malaspina, D. M., Stevens, M., ... & Whittlesey, P. (2020). Ion-scale Electromagnetic Waves in the Inner Heliosphere. The Astrophysical Journal Supplement Series, 246(2), 66.Rights
© 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Understanding the physical processes in the solar wind and corona that actively contribute to heating, acceleration, and dissipation is a primary objective of NASA's Parker Solar Probe (PSP) mission. Observations of circularly polarized electromagnetic waves at ion scales suggest that cyclotron resonance and wave-particle interactions are dynamically relevant in the inner heliosphere. A wavelet-based statistical study of circularly polarized events in the first perihelion encounter of PSP demonstrates that transverse electromagnetic waves at ion resonant scales are observed in 30-50% of radial field intervals. Average wave amplitudes of approximately 4 nT are measured, while the mean duration of wave events is on the order of 20 s; however, long-duration wave events can exist without interruption on hour-long timescales. Determination of wave vectors suggests propagation parallel/antiparallel to the mean magnetic field. Though ion-scale waves are preferentially observed during intervals with a radial mean magnetic field, we show that measurement constraints, associated with single spacecraft sampling of quasi-parallel waves superposed with anisotropic turbulence, render the measured coherent ion-wave spectrum unobservable when the mean magnetic field is oblique to the solar wind flow; these results imply that the occurrence of coherent ion-scale waves is not limited to a radial field configuration. The lack of radial scaling of characteristic wave amplitudes and duration suggests that the waves are generated in situ through plasma instabilities. Additionally, observations of proton distribution functions indicate that temperature anisotropy may drive the observed ion-scaleyISSN
0067-0049EISSN
1538-4365Version
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4365/ab6c65