# CoSMo mirror fusion (WHAM to Hammir) by Realta Fusion Canonical page: https://technooptimist.io/energy/cosmo-mirror-fusion Frontier: [Energy](https://technooptimist.io/energy.md) · Field: Alternative fusion · Company: [Realta Fusion](https://technooptimist.io/companies/realta-fusion.md) Stage: Research (1 of 5: Research → Proto → Pilot → Deploy → Scaling) Updated: last update 2026-07-15, facts checked 2026-10-11 Goal: Build fusion plants small and modular enough (50-500 MW) to sit at a factory or data centre and supply heat and power on site, using a simple old fusion geometry made workable by new superconducting magnets. Status: WHAM running at 17 T; CFS magnet deal signed; Madison R&D site; pilot plant mid-2030s. Next milestone: Prototype mirror system operating, target 2028 ## Milestones | Status | Milestone | Date | Slip | | --- | --- | --- | --- | | Done | ARPA-E funds WHAM at UW-Madison, MIT and CFS ($10M) | 2020 | | | Done | Realta spins out of the WHAM project | 2022 | | | Done | Launches with $12M: Khosla-led seed plus DOE award | 31 May 2023 | | | Done | WHAM first plasma at a record 17 tesla | 15 Jul 2024 | | | Done | $36M Series A led by Future Ventures | 13 May 2025 | | | Done | CFS to supply HTS magnets for prototypes and plants | 2 Apr 2026 | | | Done | Direct energy conversion demonstrated | Jun 2026 | | | Done | Madison headquarters and R&D site chosen | 15 Jul 2026 | | | Current | Prototype mirror system operating | 2028 | | | Planned | Hammir pilot plant | | | ## Upcoming events - **Q4 2026**: Construction of Madison R&D facility begins - **2028**: Prototype mirror system operating ## Most important updates - **15 Jul 2026**: Realta Fusion picks Madison's former Oscar Mayer plant for its headquarters and R&D site. Realta will put its headquarters and research facility in the former Oscar Mayer plant in Madison, backed by up to $55 million of state and city incentives. ([our story](https://technooptimist.io/stories/realta-fusion-picks-madison-s-former-oscar-mayer-plant-for-its-646c5ed3.md) · [original source](https://www.dailycardinal.com/article/2026/07/realta-fusion-settles-in-madisons-former-oscar-mayer-plant)) - **2 Apr 2026**: Commonwealth Fusion Systems will build the superconducting magnets for Realta's mirror fusion machines. CFS will design and manufacture high-temperature superconducting magnets for Realta's demonstration prototypes and commercial plants, and lend staff to help design, build and run them. ([our story](https://technooptimist.io/stories/commonwealth-fusion-systems-will-build-the-superconducting-magnets-for-1d696925.md) · [original source](https://cfs.energy/news-and-media/realta-fusion-and-commonwealth-fusion-systems-form-strategic-partnership-to-commercialize-magnetic-mirror-fusion-energy/)) - **13 May 2025**: Realta Fusion raises a $36 million Series A led by Future Ventures. Realta closed an oversubscribed $36 million Series A led by Future Ventures, with Khosla Ventures and others. ([our story](https://technooptimist.io/stories/realta-fusion-raises-a-36-million-series-a-led-by-future-ventures-f0ca1ce8.md) · [original source](https://pulse2.com/realta-36-million-series-a-closed-for-fusion-energy-platform)) - **18 Jul 2024**: Realta and UW-Madison's WHAM holds plasma at 17 tesla, the first HTS-magnet mirror. WHAM, the Wisconsin HTS Axisymmetric Mirror built by UW-Madison with Realta, made its first plasma on 15 July 2024 using 17-tesla high-temperature superconducting magnets from Commonwealth Fusion Systems. ([our story](https://technooptimist.io/stories/realta-and-uw-madison-s-wham-holds-plasma-at-17-tesla-the-first-hts-3386ce6b.md) · [original source](https://ans.org/news/article-6242/wham-realta-gets-first-plasma-with-17-tesla-magnets-in-mirror-fusion-test)) ## Current obstacles - **Scale-up from WHAM**: WHAM proved the magnets; it has not shown fusion-relevant plasma performance. The prototype must show far better confinement. - **Capital**: Venture equity so far is about $45M; the CEO says the company still has significant capital needs for its prototype and pilot plant. ## Physics limits - **Open ends always leak**: Particles that collide and end up moving along the field lines slip through the ends; confinement depends on the end magnets and electric plugs, never on a closed loop. - **Magnets near a hot plasma**: Superconducting magnets must stay at cryogenic temperatures metres from a plasma of tens of millions of degrees and its neutrons, which needs heavy shielding. ## How it works ### Mirror: Fields that bounce particles back Charged particles spiral along field lines; where the field squeezes tighter at each end, most are pushed back toward the middle. ### Mirror ratio: Why magnet strength matters The stronger the ends relative to the middle, the fewer particles escape. Ratios near 2 never reached breakeven; 10 or more might. ### Heating: Microwaves and neutral beams Microwaves heat the electrons; injected beams of fast neutral atoms supply hot ions that bounce between the ends. ### Tandem mirror: Electric plugs at both ends Hammir adds dense end cells whose electric potential pushes escaping ions back into a long central cell where fusion happens. ## Spec sheet | Spec | CoSMo mirror fusion (WHAM to Hammir) | Provenance | | --- | --- | --- | | WHAM peak magnetic field | 17 tesla | reported | | Planned plant size | 50-500 MW | reported | | WHAM startup heating | 110 GHz microwaves | reported | | Employees | About 50 (July 2026) | reported | Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure. ## About Realta Fusion Madison, Wisconsin spinout of the University of Wisconsin's WHAM experiment, developing compact magnetic-mirror fusion plants of 50-500 MW to supply heat and power on site to industry. - WHAM, its joint experiment with UW-Madison, held plasma at a record 17 tesla in 2024 using CFS magnets. - April 2026: CFS to build the superconducting magnets for its prototypes and plants, a deal it says could be worth billions. - About $45M in venture equity plus $9.5M debt; one of eight firms in DOE's Milestone-Based Fusion Development Program. - Founded: 2022 - Headquarters: US - Status: private - Raised: $55M - Last round: Growth debt facility $9.5M, Feb 2026, led by Silicon Valley Bank - Website: https://realtafusion.com - People: Kieran Furlong (Co-founder and CEO); Cary Forest (Co-founder and Chief Scientific Officer) - Partners, customers, investors: Commonwealth Fusion Systems (supplier); University of Wisconsin-Madison (partner); Future Ventures (investor); Khosla Ventures (investor) Company page: https://technooptimist.io/companies/realta-fusion.md ## Related programs Everything in Energy: https://technooptimist.io/energy.md --- The Techno Optimist tracks every frontier of technology, program by program: https://technooptimist.io/ (a Markdown version of any page: add .md to its URL; site map for agents: https://technooptimist.io/llms.txt). 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