Record heat shield against steady-state heat flux 100 MW/m² (not only) for tokamaks

Record heat shield against steady-state heat flux 100 MW/m² (not only) for tokamaks | 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 Article Record heat shield against steady-state heat flux 100 MW/m² (not only) for tokamaks Jan Horacek, Vaclav Sedmidubsky, Anna Horachek, Jan Prevratil, and 11 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7108147/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Effectively withstanding the extreme surface heat fluxes, possibly exceeding the limit 20 MW/m² of the best nowadays shields, continues to pose one of the last few major unresolved engineering challenges for a practical thermonuclear fusion reactor. We present a novel STEAM heat shield aimed for a tokamak or stellarator divertors and potentially applicable also in microwave gyrotrons, high power microelectronics or solid rocket combustion chambers. It employs high-speed liquid impingement cooling, developed and systematically validated under extreme heat flux conditions. The design facilitates efficient boiling-driven heat removal. It is tested on a plasma torch, supported by heat transfer simulations, infrared thermography and calorimetry. Our shield sustained for over 20 minutes a steady-state heat flux of 73 MW/m² (31 kW across 4.2 cm²), exceeding conditions on the Sun. Fast camera revealed a strongly boiling outlet of an open water circuit and shape-optimized water injector. Even more, exactly where thermovision indirectly indicated that most liquid changes phase into steam, the STEAM survived for 1 minute under heat flux reaching 130 MW/m² — representing the most intensive sustained non-destructive heat shield test ever reported. Physical sciences/Energy science and technology/Nuclear energy/Nuclear fusion and fission Physical sciences/Physics/Statistical physics, thermodynamics and nonlinear dynamics/Phase transitions and critical phenomena Physical sciences/Physics/Plasma physics/Magnetically confined plasmas Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-7108147","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":497107224,"identity":"e56c9012-cf2b-470f-801c-62b06f39f4af","order_by":0,"name":"Jan 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