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Ion Bernstein instability as a possible source for oxygen ion cyclotron harmonic waves


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dc.contributorKaijun Liuen_US
dc.creatorMin, Kyungguk
dc.creatorDenton, Richard E.
dc.creatorLiu, Kaijun
dc.creatorGary, S. Peter
dc.creatorSpence, Harlan E.
dc.date.accessioned2020-06-01T18:36:24Z
dc.date.available2020-06-01T18:36:24Z
dc.date.created2017-05
dc.identifier10.1002/2017JA023979en_US
dc.identifier.urihttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JA023979en_US
dc.identifier.urihttp://hdl.handle.net/11200/49836
dc.description.abstractThis paper demonstrates that an ion Bernstein instability can be a possible source for recently reported electromagnetic waves with frequencies at or near the singly ionized oxygen ion cyclotron frequency, Omega(+)(O), and its harmonics. The particle measurements during strong wave activity revealed a relatively high concentration of oxygen ions (similar to 15%) whose phase space density exhibits a local peak at energy similar to 20 keV. Given that the electron plasma-to-cyclotron frequency ratio is omega(pe)/Omega(e) greater than or similar to 1, this energy corresponds to the particle speed v/v(A) . greater than or similar to 0.3, where v(A) is the oxygen Alfven speed. Using the observational key plasma parameters, a simplified ion velocity distribution is constructed, where the local peak in the oxygen ion velocity distribution is represented by an isotropic shell distribution. Kinetic linear dispersion theory then predicts unstable Bernstein modes at or near the harmonics of Omega(+)(O) and at propagation quasi-perpendicular to the background magnetic field, B-0. If the cold ions are mostly protons, these unstable modes are characterized by a low compressibility (vertical bar delta B-parallel to vertical bar(2)/vertical bar delta B vertical bar(2) less than or similar to 0.01), a small phase speed (v(ph) similar to 0.2v(A)), a relatively small ratio of the electric field energy to the magnetic field energy (between 10(-4) and 10(-3)), and the Poynting vector directed almost parallel to B-0. These linear properties are overall in good agreement with the properties of the observed waves. We demonstrate that superposition of the predicted unstable Bernstein modes at quasi-perpendicular propagation can produce the observed polarization properties, including the minimum variance direction on average almost parallel to B-0.en_US
dc.formatPDFen_US
dc.publisherAMER GEOPHYSICAL UNIONen_US
dc.relation.ispartofJOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICSen_US
dc.relation.ispartofseries2169-9380en_US
dc.subjectEQUATORIAL MAGNETOSONIC WAVES; ULF WAVES; POLARIZATION; PLASMA; PROTON; DRIVEN; PARTICLEen_US
dc.titleIon Bernstein instability as a possible source for oxygen ion cyclotron harmonic wavesen_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume122en_US
dc.citation.issue5en_US
dc.citation.spage5449en_US
dc.citation.epage5465en_US
dc.description.statusPublisheden_US
dc.creator.orcid0000-0001-5882-1328en_US

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