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Understanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributions


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dc.contributorKyungguk Minen_US
dc.creatorMin, Kyungguk
dc.creatorLiu, Kaijun
dc.date.accessioned2020-06-03T13:33:26Z
dc.date.available2020-06-03T13:33:26Z
dc.date.created2016-04
dc.identifier10.1002/2016JA022524en_US
dc.identifier.urihttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JA022524en_US
dc.identifier.urihttp://hdl.handle.net/11200/49845
dc.description.abstractFast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (f(p)) with partial derivative f(p)(v(perpendicular to))/partial derivative v(perpendicular to) > 0. Two typical types of distributions with such features are ring and shell velocity distributions. Both have been used in studies of ion Bernstein instabilities and fast magnetosonic waves, but the differences between instabilities driven by the two types of distributions have not been thoroughly addressed. The present study uses linear kinetic theory to examine and understand these differences. It is found that the growth rate pattern is primarily determined by the cyclotron resonance condition and the structure of the velocity distribution in gyroaveraged velocity space. For ring-driven Bernstein instabilities, as the parallel wave number (k(parallel to)) increases, the discrete unstable modes approximately follow the corresponding proton cyclotron harmonic frequencies while they become broader in frequency space. At sufficiently large k(parallel to), the neighboring discrete modes merge into a continuum. In contrast, for shell-driven Bernstein instabilities, the curved geometry of the shell velocity distribution in gyroaveraged velocity space results in a complex alternating pattern of growth and damping rates in frequency and wave number space and confines the unstable Bernstein modes to relatively small k(parallel to) In addition, when k(parallel to) increases, the unstable modes are no longer limited to the proton cyclotron harmonic frequencies. The local growth rate peak near an exact harmonic at small k(parallel to) bifurcates into two local peaks on both sides of the harmonic when k(parallel to) becomes large.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.subjectFAST MAGNETOSONIC WAVES; VAN ALLEN PROBES; EQUATORIAL NOISE; INNER MAGNETOSPHERE; DISPERSION-RELATION; MAGNETIC EQUATOR; ULF WAVES; EXCITATION; FREQUENCY; GENERATIONen_US
dc.titleUnderstanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributionsen_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume121en_US
dc.citation.issue4en_US
dc.citation.spage3036en_US
dc.citation.epage3049en_US
dc.description.statusPublisheden_US
dc.creator.orcid0000-0002-2095-8529en_US
dc.creator.orcid0000-0001-5882-1328en_US

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