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Characteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability

dc.contributor.authorK. Seki
dc.contributor.authorY. Matsumoto
dc.contributor.authorN. Terada
dc.contributor.authorT. Hara
dc.contributor.authorD. A. Brain
dc.contributor.authorH. Nakagawa
dc.contributor.authorJ. P. McFadden
dc.contributor.authorJ. S. Halekas
dc.contributor.authorS. Ruhunusiri
dc.contributor.authorD. L. Mitchell
dc.contributor.authorL. Andersson
dc.contributor.authorJ. R. Espley
dc.contributor.authorD. N. Baker
dc.contributor.authorJ. G. Luhmann
dc.contributor.authorB. M. Jakosky
dc.contributor.otherDepartment of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Tokyo, Japan
dc.contributor.otherInstitute for Advanced Academic Research, Chiba University, Chiba, Japan
dc.contributor.otherGraduate School of Science, Tohoku University, Sendai, Japan
dc.contributor.otherSpace Sciences Laboratory, University of California, Berkeley, CA, United States
dc.contributor.otherLaboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
dc.contributor.otherGraduate School of Science, Tohoku University, Sendai, Japan
dc.contributor.otherSpace Sciences Laboratory, University of California, Berkeley, CA, United States
dc.contributor.otherDepartment of Physics and Astronomy, University of Iowa, Iowa City, IA, United States
dc.contributor.otherLaboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
dc.contributor.otherSpace Sciences Laboratory, University of California, Berkeley, CA, United States
dc.contributor.otherLaboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
dc.contributor.otherNASA Goddard Space Flight Center, Greenbelt, MD, United States
dc.contributor.otherLaboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
dc.contributor.otherSpace Sciences Laboratory, University of California, Berkeley, CA, United States
dc.contributor.otherLaboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
dc.date.accessioned2024-05-31T04:57:31Z
dc.date.accessioned2025-10-08T09:25:44Z
dc.date.available2025-10-08T09:25:44Z
dc.date.issued01-05-2024
dc.identifier.urihttp://digilib.fisipol.ugm.ac.id/repo/handle/15717717/40344
dc.description.abstractBoundaries between space plasmas occur in numerous contexts and scales, from astrophysical jets to planetary magnetospheres. Mass and momentum transport across boundaries poses a fundamental problem in magnetospheric physics. Kelvin–Helmholtz instability (KHI) is a promising mechanism to facilitate transport. Although previous studies have suggested KHI occurrence in various space plasmas, theory predicts that compressibility prevents KHI excitation at boundaries with large density gradients because of previously considered boundary structures where density varies with velocity. Based on the observations of a large density gradient boundary by MAVEN at Mars, where we can observe an extreme case, in this study, we show that it is the entropy, instead of the previously considered density, that varies with the velocity in the real velocity-sheared boundary. The entropy-based boundary structure places the velocity shear in a lower-density region than the traditional density-based structure and weakens the compressibility effect. This new boundary structure thus enables KHI excitation even at large density gradient boundaries, such as at the ionopause of unmagnetized planets and the plasmapause of magnetized planets. The result suggests the ubiquitous occurrence of KHI in the plasma universe and emphasizes its important role in planetary cold plasma escape from unmagnetized planets.
dc.language.isoEN
dc.publisherFrontiers Media S.A.
dc.subject.lccAstronomy
dc.titleCharacteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability
dc.typeArticle
dc.description.keywordsKelvin–Helmholtz instability
dc.description.keywordsMars
dc.description.keywordsdensity gradient
dc.description.keywordscompressibility
dc.description.keywordscold plasma
dc.description.keywordsMAVEN
dc.description.doi10.3389/fspas.2024.1394817
dc.title.journalFrontiers in Astronomy and Space Sciences
dc.identifier.e-issn2296-987X
dc.identifier.oaioai:doaj.org/journal:9bacb495e22d413aa3ee8d33b4d3f73d


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