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Scalings of Alfven-cyclotron and ion Bernstein instabilities on temperature anisotropy of a ring-like velocity distribution in the inner magnetosphere


Metadata FieldValueLanguage
dc.contributorKyungguk Min, kmin@auburn.eduen_US
dc.creatorMin, Kyungguk
dc.creatorLiu, Kaijun
dc.creatorGary, S. Peter
dc.date.accessioned2020-06-03T13:38:53Z
dc.date.available2020-06-03T13:38:53Z
dc.date.created2016-03
dc.identifier10.1002/2015JA022134en_US
dc.identifier.urihttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JA022134en_US
dc.identifier.urihttp://hdl.handle.net/11200/49847
dc.description.abstractA ring-like proton velocity distribution with f(p)(v)/v>0 and which is sufficiently anisotropic can excite two distinct types of growing modes in the inner magnetosphere: ion Bernstein instabilities with multiple ion cyclotron harmonics and quasi-perpendicular propagation and an Alfven-cyclotron instability at frequencies below the proton cyclotron frequency and quasi-parallel propagation. Recent particle-in-cell simulations have demonstrated that even if the maximum linear growth rate of the latter instability is smaller than the corresponding growth of the former instability, the saturation levels of the fluctuating magnetic fields can be greater for the Alfven-cyclotron instability than for the ion Bernstein instabilities. In this study, linear dispersion theory and two-dimensional particle-in-cell simulations are used to examine scalings of the linear growth rate and saturation level of the two types of growing modes as functions of the temperature anisotropy T/T-parallel to for a general ring-like proton distribution with a fixed ring speed of 2v(A), where v(A) is the Alfven speed. For the proton distribution parameters chosen, the maximum linear theory growth rate of the Alfven-cyclotron waves is smaller than that of the fastest-growing Bernstein mode for the wide range of anisotropies (1T/T-parallel to <= 7) considered here. Yet the corresponding particle-in-cell simulations yield a higher saturation level of the fluctuating magnetic fields for the Alfven-cyclotron instability than for the Bernstein modes as long as T perpendicular to/T-parallel to greater than or similar to. Since fast magnetosonic waves with ion Bernstein instability properties observed in the magnetosphere are often not accompanied by electromagnetic ion cyclotron waves, the results of the present study indicate that the ring-like proton distributions responsible for the excitation of these fast magnetosonic waves should not be very anisotropic.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.subjectproton velocity shell-driven instabilities; Alfven-cyclotron instability; ion Bernstein instabilities; instability scalings on temperature anisotropyen_US
dc.subjectMAGNETOSONIC WAVES; EQUATORIAL NOISE; ULF WAVES; DRIVEN; PROTON; FREQUENCYen_US
dc.titleScalings of Alfven-cyclotron and ion Bernstein instabilities on temperature anisotropy of a ring-like velocity distribution in the inner magnetosphereen_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume121en_US
dc.citation.issue3en_US
dc.citation.spage2185en_US
dc.citation.epage2193en_US
dc.description.statusPublisheden_US
dc.creator.orcid0000-0002-2095-8529en_US
dc.creator.orcid0000-0001-5882-1328en_US

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