Ion temperature anisotropy and instability in the plasma sheet

Ion temperature anisotropy and instability in the plasma sheet | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ion temperature anisotropy and instability in the plasma sheet Ephrem Tesfaye Desta This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9604393/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Near-Earth and at lunar distances, where the terrestrial magnetotail merges into the solar wind, the PS becomes a collisionless environment dominated by temperature anisotropies and their resulting instabilities. Using THEMIS-C / ARTEMIS-P2 observations, we examine the instability and instability thresholds for different plasma flow speeds near-Earth and at lunar distances of the PS. We also compare the threshold instability and how ion anisotropies T⊥/T∥ regulate plasma dynamics through the onset of firehose, mirror, and cyclotron instabilities near-Earth and at lunar distances for different flow speeds. We found that most ions flowing at slow speeds (< 10 km s −1 ) near-Earth and at lunar distances are stable. The results reveal frequent intervals where the plasma approaches or exceeds kinetic instability thresholds, indicating active wave–particle coupling in the high-β regime. Additionally, we find that the FI are observed to be more dominant, while most ion data points are stable in the mirror and cyclotron modes during the PS intervals. These findings demonstrate that the distant magnetotail operates as a natural laboratory for anisotropy-driven instabilities, linking microscale kinetic physics to the large-scale structure of Earth’s extended magnetosphere. Space Exploration Plasma and Fluids Planetary Science Plasma sheet instability anisotropy space plasma lunar distances Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9604393","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":635209381,"identity":"7e6d4b37-ccef-444a-b420-b196bb5fe9c6","order_by":0,"name":"Ephrem Tesfaye Desta","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEklEQVRIiWNgGAWjYFACHhiD8QGQsEETxKNFgoGB2QBIpyEEcWtD1XKYsBZ+6d5jHz7mMNTx8x9m/MxTcV6ef0YC44O3bQxy9ji0SM45lzxz5jYGCckZyczSPGduG864kcBsOLeNwRiXLQY3coyZeYFaDG7wH5DmbbvN2HAjgQ3IYEjswaHFHqTlL1CL/fnDzL95/52zn38jgf03UEs9Li0GEkAtjCBbGJKBhjccSNwAtIUZqCUBl8Mk7pwxZuzdBvTKjWQ2yznHkpM3nnnYDPShhGHPARwhNrvHmOHnNht+/v7DzDfe1NjZzjuefPDDmzIbefYGXNYgkUwQtzA2wEXwaIEAxh+41Y2CUTAKRsEIBgAFq1LUcsceiQAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-5502-3064","institution":"Addis Ababa University","correspondingAuthor":true,"prefix":"","firstName":"Ephrem","middleName":"Tesfaye","lastName":"Desta","suffix":""}],"badges":[],"createdAt":"2026-05-04 05:49:20","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9604393/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-9604393/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108806430,"identity":"c08ed92f-b30f-487a-84f8-f7ee2d221d7e","added_by":"auto","created_at":"2026-05-08 15:28:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":869719,"visible":true,"origin":"","legend":"","description":"","filename":"ephremepsp2026av1clean.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9604393/v2_covered_7c4b6660-d1b2-4c2f-80ff-4432a2e28fbb.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"Ion temperature anisotropy and instability in the plasma sheet","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Addis Ababa University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Plasma sheet, instability, anisotropy, space plasma, lunar distances","lastPublishedDoi":"10.21203/rs.3.rs-9604393/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9604393/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eNear-Earth and at lunar distances, where the terrestrial magnetotail merges into the solar wind, the PS becomes a collisionless environment dominated by temperature anisotropies and their resulting instabilities. 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