Key Takeaways
- • Hephaestus emerged from stealth and announced the close of a funding round totaling $17.2M, led by CiRi Ventures, to address two major cost drivers in fusion power.
- • The company plans to begin HTS magnet manufacturing at a new 70,000 ft² New Jersey facility in 2027, using rare-earth-free superconducting materials developed with its MaDi-AI discovery platform.
- • Hephaestus targets a net gain demonstration reactor (Q>1) by 2030 to demonstrate the commercial advantages of its negative triangularity plasma configuration.
- • Existing investors include Prescience Ventures, Teampact Ventures, Climate Capital, Unruly Capital, and CiRi Ventures.
- • The company is positioning itself as a foundational HTS supplier to the wider fusion sector, with early-access discussions already open with fusion developers.
Summary
London-based Hephaestus, founded in 2019, emerged from stealth on the Business Wire with solutions targeting the high temperature superconducting (HTS) magnets that confine plasma and the edge-localized modes (ELMs) that raise the cost and complexity of conventional reactor designs. The company announced the close of a new funding round led by CiRi Ventures, bringing the total raised to $17.2M according to the headline figure. Existing investors include Prescience Ventures, Teampact Ventures, Climate Capital, Unruly Capital, and CiRi Ventures.
The company's technical strategy rests on negative triangularity (NT), a configuration that inverts the D-shaped plasma used in most tokamaks. Hephaestus's AI plasma solver identified NT as the most likely route to low-cost fusion, and the company states that results from facilities including DIII-D, JET, and SMART have shown NT can deliver strong performance without ELM instabilities. Antoine Pochelon, a former EPFL researcher and one of the field's leading NT authorities, joined as co-founder and Head of the Experimental Campaign in February 2021. The company's first device, Anvil 0, described as the world's first tokamak designed for NT from inception, was completed in 2024.
On the materials side, Hephaestus uses its proprietary MaDi-AI platform to develop rare-earth-free HTS materials. The company says it has identified, manufactured, and characterized several novel HTS materials at lab scale, validated by the UK's National Physical Laboratory. The company contrasts these with REBCO (rare-earth barium copper oxide), the material used in every HTS fusion magnet today, which it describes as slow and expensive to scale and concentrated in geopolitically risky regions.
The new capital will fund HTS manufacturing at the New Jersey facility starting in 2027 and a planned 2030 demonstration of NT's commercial advantages in a net gain reactor. CEO and founder Jack Zamattio said fusion's grid potential depends on affordability and scalability. The company has opened early-access discussions with fusion developers seeking HTS supply and is hiring across its New Jersey, London, and Rome sites. Hephaestus also lists offices in New York.
The company's technical strategy rests on negative triangularity (NT), a configuration that inverts the D-shaped plasma used in most tokamaks. Hephaestus's AI plasma solver identified NT as the most likely route to low-cost fusion, and the company states that results from facilities including DIII-D, JET, and SMART have shown NT can deliver strong performance without ELM instabilities. Antoine Pochelon, a former EPFL researcher and one of the field's leading NT authorities, joined as co-founder and Head of the Experimental Campaign in February 2021. The company's first device, Anvil 0, described as the world's first tokamak designed for NT from inception, was completed in 2024.
On the materials side, Hephaestus uses its proprietary MaDi-AI platform to develop rare-earth-free HTS materials. The company says it has identified, manufactured, and characterized several novel HTS materials at lab scale, validated by the UK's National Physical Laboratory. The company contrasts these with REBCO (rare-earth barium copper oxide), the material used in every HTS fusion magnet today, which it describes as slow and expensive to scale and concentrated in geopolitically risky regions.
The new capital will fund HTS manufacturing at the New Jersey facility starting in 2027 and a planned 2030 demonstration of NT's commercial advantages in a net gain reactor. CEO and founder Jack Zamattio said fusion's grid potential depends on affordability and scalability. The company has opened early-access discussions with fusion developers seeking HTS supply and is hiring across its New Jersey, London, and Rome sites. Hephaestus also lists offices in New York.
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