Evidence for Gain in Trapped Ions and a Cavity Concept for Future X-ray Laser

Evidence for Gain in Trapped Ions and a Cavity Concept for Future X-ray Laser | 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 Evidence for Gain in Trapped Ions and a Cavity Concept for Future X-ray Laser Shuang Li, Yan Wang, Yuxuan Li, Hao Zhou, Xuelian Chong, Yanran Luo, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7320144/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Coherent X-ray sources are indispensable tools in probing microstructures, resolving ultrafast dynamics, and investigating related phenomena, yet current technologies suffer from irreconcilable trade-offs between miniaturization, high brightness, high coherence, and high repetition rates---forming a critical bottleneck. Here, to our knowledge, we present the first theoretical validation of a groundbreaking ''non-plasma" X-ray laser gain medium. This approach employs ion trapping and cooling techniques to generate and confine highly charged Neon-like (or Ne-like) ions in an ultra-high vacuum environment, where ion excitation is achieved via collisions with a fixed-direction quasi-monoenergetic electron beam. Through first-principles simulations integrating the fully relativistic Flexible Atomic Code (FAC) and collisional-radiative models (CRM), we first validate our theoretical framework against established plasma-based scenarios, then extended to the ''non-plasma" regime and, rigorously demonstrate that excitation of highly charged Ne-like ions (Kr, Xe, W, U) by a fixed-direction quasi-monoenergetic electron beam can effectively achieve population inversion---establishing its principle feasibility. This analysis identifies a series of potential X-ray laser transitions spanning wavelengths from 0.45 nm to 9.88 nm, with small-signal gain coefficients ranging from 0.005 cm -1 to 59 cm -1 for electron densities between 1 × 10 19 cm -3 and 1 × 10 22 cm -3 To realise practical X-ray lasing, we further propose constructing an X-ray cavity using two high-reflectivity Bragg-diffracting crystals with specialised facets and two compound refractive lenses (CRLs), enabling coherent X-ray emission in a ''driver-laser-free" and ''non-plasma" environment. This work provides a critical theoretical foundation for developing compact, high-brightness, highly coherent X-ray lasers with high repetition rates and even continuous-wave operation. It indicates the potential transformation of X-ray lasers from ''big-science'' facilities to standard laboratory platforms, opening new ways for advances in materials science, life sciences, semiconductor lithography, and beyond. Physical sciences/Optics and photonics/Lasers, LEDs and light sources Physical sciences/Physics/Atomic and molecular physics X-ray laser X-ray cavity Collisional radiative model Gain coefficient Full Text Additional Declarations There is NO Competing Interest. Supplementary Files snarticlerevised20250807tablea1pop.pdf supplementary table a1 snarticlerevised20250807tablea2gain.pdf supplementary table a2 Cite Share Download PDF Status: Under Review 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. 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-7320144","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":503909524,"identity":"89da1604-2edc-4bd0-8f23-f3d61b766484","order_by":0,"name":"Shuang 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coefficient","lastPublishedDoi":"10.21203/rs.3.rs-7320144/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7320144/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCoherent X-ray sources are indispensable tools in probing microstructures, resolving ultrafast dynamics, and investigating related phenomena, yet current technologies suffer from irreconcilable trade-offs between miniaturization, high brightness, high coherence, and high repetition rates---forming a critical bottleneck. Here, to our knowledge, we present the first theoretical validation of a groundbreaking ''non-plasma\" X-ray laser gain medium. This approach employs ion trapping and cooling techniques to generate and confine highly charged Neon-like (or Ne-like) ions in an ultra-high vacuum environment, where ion excitation is achieved via collisions with a fixed-direction quasi-monoenergetic electron beam. Through first-principles simulations integrating the fully relativistic Flexible Atomic Code (FAC) and collisional-radiative models (CRM), we first validate our theoretical framework against established plasma-based scenarios, then extended to the ''non-plasma\" regime and, rigorously demonstrate that excitation of highly charged Ne-like ions (Kr, Xe, W, U) by a fixed-direction quasi-monoenergetic electron beam can effectively achieve population inversion---establishing its principle feasibility. This analysis identifies a series of potential X-ray laser transitions spanning wavelengths from 0.45 nm to 9.88 nm, with small-signal gain coefficients ranging from \u003cstrong\u003e0.005 \u003c/strong\u003ecm\u003csup\u003e-1 \u003c/sup\u003eto \u003cstrong\u003e59\u003c/strong\u003e cm\u003csup\u003e\u003cstrong\u003e-1\u003c/strong\u003e\u003c/sup\u003e for electron densities between \u003cstrong\u003e1 × 10\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e19\u003c/strong\u003e\u003c/sup\u003e \u003cstrong\u003ecm\u003c/strong\u003e\u003csup\u003e-3 \u003c/sup\u003eand \u0026nbsp;\u003cstrong\u003e1 × 10\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e22\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e cm\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e-3\u003c/strong\u003e\u003c/sup\u003e To realise practical X-ray lasing, we further propose constructing an X-ray cavity using two high-reflectivity Bragg-diffracting crystals with specialised facets and two compound refractive lenses (CRLs), enabling coherent X-ray emission in a ''driver-laser-free\" and ''non-plasma\" environment. This work provides a critical theoretical foundation for developing compact, high-brightness, highly coherent X-ray lasers with high repetition rates and even continuous-wave operation. It indicates the potential transformation of X-ray lasers from ''big-science'' facilities to standard laboratory platforms, opening new ways for advances in materials science, life sciences, semiconductor lithography, and beyond.\u003c/p\u003e","manuscriptTitle":"Evidence for Gain in Trapped Ions and a Cavity Concept for Future X-ray Laser","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-10 04:58:35","doi":"10.21203/rs.3.rs-7320144/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b3f4724f-e996-400b-98d4-2ff1db3c339e","owner":[],"postedDate":"September 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":53536380,"name":"Physical sciences/Optics and photonics/Lasers, LEDs and light sources"},{"id":53536381,"name":"Physical sciences/Physics/Atomic and molecular physics"}],"tags":[],"updatedAt":"2025-09-10T04:58:35+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-10 04:58:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7320144","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7320144","identity":"rs-7320144","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}