High-Speed Shadowgraph Imaging for Measuring the Thermal Expansion of Niobium under Pulsed-Current Heating beyond 2000 K

High-Speed Shadowgraph Imaging for Measuring the Thermal Expansion of Niobium under Pulsed-Current Heating beyond 2000 K | 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 High-Speed Shadowgraph Imaging for Measuring the Thermal Expansion of Niobium under Pulsed-Current Heating beyond 2000 K Isamu Orikasa, Hiromichi Watanabe This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6952220/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 Sep, 2025 Read the published version in International Journal of Thermophysics → Version 1 posted 9 You are reading this latest preprint version Abstract A high-speed shadowgraph technique was developed to measure the linear thermal expansion of metallic solids above 2000 K during pulsed-current heating in vacuum. Niobium coupon specimens (3 mm × 0.5 mm × 100 mm) were resistively heated with a direct current of over 100 A for up to 2.3 s. The system incorporates a 405 nm bandpass filter, a Type-C thermocouple welded to the specimen surface, and a high-speed CMOS camera to enable high-contrast silhouette imaging under intense thermal radiation emitted by the specimen. Specimen elongation was determined by subpixel contour extraction of silhouette images, and the specimen temperature was recorded via the welded thermocouple. The linear thermal expansion and average coefficients of thermal expansion (CTE) were evaluated under three temperature conditions, yielding a maximum linear expansion of 1.88 × 10 − 2 between 340 K and 2355 K and an average CTE of 9.30 × 10 − 6 K − 1 at a mean temperature of 1344 K. The relative deviation from literature values remained below 1.1 × 10 − 7 K − 1 , and the combined standard uncertainty of the CTE measurement was 1.73 × 10 − 7 K⁻¹ (1.85%), including a 0.02% contribution from temperature non-uniformity across the specimen surface. These results confirm the method’s validity for rapid, precise, non-contact thermal expansion measurement above 2000 K. Linear thermal expansion high temperature Shadowgraphy Pulse heating Uncertainty evaluation Niobium (Nb) Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 09 Sep, 2025 Read the published version in International Journal of Thermophysics → Version 1 posted Editorial decision: Revision requested 17 Jul, 2025 Reviews received at journal 17 Jul, 2025 Reviews received at journal 11 Jul, 2025 Reviewers agreed at journal 29 Jun, 2025 Reviewers agreed at journal 28 Jun, 2025 Reviewers invited by journal 23 Jun, 2025 Editor assigned by journal 23 Jun, 2025 Submission checks completed at journal 23 Jun, 2025 First submitted to journal 22 Jun, 2025 You are reading this latest preprint version 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-6952220","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":475972633,"identity":"e90184cb-cb71-4efb-b62a-ada0efb93dfd","order_by":0,"name":"Isamu Orikasa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIie3SMQrCMBSA4SeBugRd66JXCLhKc5VXAnFxcHew4OAiuNpbKF4gEmiXHqDiUhGc61Y3I7qIUOMmkn8IJOSDFwiAy/WDefcFlVmaEajnIVoSqgxBC/LoTny0vNwCkpRFFvB2fDrurhUES4BzUT+YJ1aYi3B1kExTBBFHMGT1hPYBS4JwQKbNYIIpkL4FmfLePi13lT3JdWOdU6bMYMFnQjwBmKXhJhuNNZU+dmYf3tKbz3SjSia8m6bbSzUY8HZzIYs6AuR164cRobJWvMXN10m+Iy6Xy/Xv3QAWMkevyYuGegAAAABJRU5ErkJggg==","orcid":"","institution":"National Institute of Advanced Industrial Science and Technology (AIST)","correspondingAuthor":true,"prefix":"","firstName":"Isamu","middleName":"","lastName":"Orikasa","suffix":""},{"id":475972636,"identity":"cd02ab81-2e8b-42c0-99a5-0b9b27ddf93f","order_by":1,"name":"Hiromichi Watanabe","email":"","orcid":"","institution":"National Institute of Advanced Industrial Science and Technology (AIST)","correspondingAuthor":false,"prefix":"","firstName":"Hiromichi","middleName":"","lastName":"Watanabe","suffix":""}],"badges":[],"createdAt":"2025-06-23 03:08:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6952220/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6952220/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10765-025-03636-z","type":"published","date":"2025-09-09T15:57:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":91359054,"identity":"5441a61e-135d-4445-b332-fe762a10a6bb","added_by":"auto","created_at":"2025-09-15 16:04:38","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1246278,"visible":true,"origin":"","legend":"","description":"","filename":"ManuscriptIOHWAIST.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6952220/v1_covered_c3dd6afb-80c0-4124-99b1-6be406fcbc0e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"High-Speed Shadowgraph Imaging for Measuring the Thermal Expansion of Niobium under Pulsed-Current Heating beyond 2000 K","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-thermophysics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijot","sideBox":"Learn more about [International Journal of Thermophysics](http://link.springer.com/journal/10765)","snPcode":"10765","submissionUrl":"https://submission.nature.com/new-submission/10765/3","title":"International Journal of Thermophysics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Linear thermal expansion, high temperature, Shadowgraphy, Pulse heating, Uncertainty evaluation, Niobium (Nb)","lastPublishedDoi":"10.21203/rs.3.rs-6952220/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6952220/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA high-speed shadowgraph technique was developed to measure the linear thermal expansion of metallic solids above 2000 K during pulsed-current heating in vacuum. Niobium coupon specimens (3 mm \u0026times; 0.5 mm \u0026times; 100 mm) were resistively heated with a direct current of over 100 A for up to 2.3 s. The system incorporates a 405 nm bandpass filter, a Type-C thermocouple welded to the specimen surface, and a high-speed CMOS camera to enable high-contrast silhouette imaging under intense thermal radiation emitted by the specimen. Specimen elongation was determined by subpixel contour extraction of silhouette images, and the specimen temperature was recorded via the welded thermocouple. The linear thermal expansion and average coefficients of thermal expansion (CTE) were evaluated under three temperature conditions, yielding a maximum linear expansion of 1.88 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e between 340 K and 2355 K and an average CTE of 9.30 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at a mean temperature of 1344 K. The relative deviation from literature values remained below 1.1 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and the combined standard uncertainty of the CTE measurement was 1.73 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e K⁻\u0026sup1; (1.85%), including a 0.02% contribution from temperature non-uniformity across the specimen surface. These results confirm the method\u0026rsquo;s validity for rapid, precise, non-contact thermal expansion measurement above 2000 K.\u003c/p\u003e","manuscriptTitle":"High-Speed Shadowgraph Imaging for Measuring the Thermal Expansion of Niobium under Pulsed-Current Heating beyond 2000 K","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-26 13:33:06","doi":"10.21203/rs.3.rs-6952220/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-07-17T07:52:26+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-17T07:44:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-11T18:52:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192986204831264893970532940898921656562","date":"2025-06-29T14:05:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"261698033994859883453704870615090582510","date":"2025-06-28T13:31:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-23T08:44:31+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-23T07:03:01+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-23T07:00:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Journal of Thermophysics","date":"2025-06-23T03:00:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-journal-of-thermophysics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijot","sideBox":"Learn more about [International Journal of Thermophysics](http://link.springer.com/journal/10765)","snPcode":"10765","submissionUrl":"https://submission.nature.com/new-submission/10765/3","title":"International Journal of Thermophysics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d2f67562-1851-4249-9288-9fd61e88fc64","owner":[],"postedDate":"June 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-15T16:01:09+00:00","versionOfRecord":{"articleIdentity":"rs-6952220","link":"https://doi.org/10.1007/s10765-025-03636-z","journal":{"identity":"international-journal-of-thermophysics","isVorOnly":false,"title":"International Journal of Thermophysics"},"publishedOn":"2025-09-09 15:57:37","publishedOnDateReadable":"September 9th, 2025"},"versionCreatedAt":"2025-06-26 13:33:06","video":"","vorDoi":"10.1007/s10765-025-03636-z","vorDoiUrl":"https://doi.org/10.1007/s10765-025-03636-z","workflowStages":[]},"version":"v1","identity":"rs-6952220","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6952220","identity":"rs-6952220","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}