Van Allen Probes Observations of Second Harmonic Poloidal Standing Alfvén Waves

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dc.citation.firstpage611
dc.citation.issueNumber1
dc.citation.journalTitleJournal of Geophysical Research: Space Physics
dc.citation.lastpage637
dc.citation.volumeNumber123
dc.contributor.authorTakahashi, Kazue
dc.contributor.authorOimatsu, Satoshi
dc.contributor.authorNosé, Masahito
dc.contributor.authorMin, Kyungguk
dc.contributor.authorClaudepierre, Seth G.
dc.contributor.authorChan, Anthony
dc.contributor.authorWygant, John
dc.contributor.authorKim, Hyomin
dc.date.accessioned2018-07-11T20:57:33Z
dc.date.available2018-07-11T20:57:33Z
dc.date.issued2018
dc.description.abstractLong-lasting second-harmonic poloidal standing Alfvén waves (P2 waves) were observed by the twin Van Allen Probes (Radiation Belt Storm Probes, or RBSP) spacecraft in the noon sector of the plasmasphere, when the spacecraft were close to the magnetic equator and had a small azimuthal separation. Oscillations of proton fluxes at the wave frequency (∼10 mHz) were also observed in the energy (W) range 50–300 keV. Using the unique RBSP orbital configuration, we determined the phase delay of magnetic field perturbations between the spacecraft with a 2nπ ambiguity. We then used finite gyroradius effects seen in the proton flux oscillations to remove the ambiguity and found that the waves were propagating westward with an azimuthal wave number (m) of ∼−200. The phase of the proton flux oscillations relative to the radial component of the wave magnetic field progresses with W, crossing 0 (northward moving protons) or 180° (southward moving protons) at W ∼ 120 keV. This feature is explained by drift-bounce resonance (mωd ∼ ωb) of ∼120 keV protons with the waves, where ωd and ωb are the proton drift and bounce frequencies. At lower energies, the proton phase space density ( ) exhibits a bump-on-tail structure with occurring in the 1–10 keV energy range. This is unstable and can excite P2 waves through bounce resonance (ω ∼ ωb), where ω is the wave frequency.
dc.identifier.citationTakahashi, Kazue, Oimatsu, Satoshi, Nosé, Masahito, et al.. "Van Allen Probes Observations of Second Harmonic Poloidal Standing Alfvén Waves." <i>Journal of Geophysical Research: Space Physics,</i> 123, no. 1 (2018) Wiley: 611-637. https://doi.org/10.1002/2017JA024869.
dc.identifier.doihttps://doi.org/10.1002/2017JA024869
dc.identifier.urihttps://hdl.handle.net/1911/102414
dc.language.isoeng
dc.publisherWiley
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.titleVan Allen Probes Observations of Second Harmonic Poloidal Standing Alfvén Waves
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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