Hephaestus, a London-based fusion energy company, is emerging from stealth with a $17.2 million round led by CiRi Ventures. The announcement was made on October 21, 2026. The funds will go toward producing rare-earth-free high-temperature superconductors (HTS) and a demonstration reactor planned by 2030.
Prescience Ventures, Teampact Ventures, Climate Capital and Unruly Capital also joined the round. The company was founded in London in 2019, has offices in London, Rome and New York, and operates a large manufacturing facility in New Jersey. It is there, in a new plant of roughly 70,000 square feet, that HTS magnet production will begin in 2027. Hephaestus is hiring across all three European and American locations and has started early-access talks with other fusion developers interested in securing supply.
The first line of work concerns materials. The HTS magnets used in fusion today are made from REBCO, a rare-earth barium copper oxide. Its production is slow, costly to scale and concentrated in geopolitically risky regions. Hephaestus is working on rare-earth-free alternatives, identified through its MaDi-AI artificial intelligence platform. The company says it has identified, produced and characterized in the lab several novel HTS materials, validated by the UK’s National Physical Laboratory.
The second line of work concerns the plasma. An AI solver explored the entire tokamak design parameter space, free from the constraints of the materials and designs already adopted by the industry. The result points to negative triangularity as the most promising configuration for low-cost fusion. This geometry inverts the typical D-shape of the plasma. According to the company, it lowers magnet costs and mitigates edge instabilities, known as ELMs, which complicate and add cost to conventional reactors. Results from facilities around the world, including DIII-D, point in the same direction.
The competitive landscape is on a different scale. Commonwealth Fusion Systems raised $1 billion in July and Tokamak Energy secured $125 million. Hephaestus is therefore also targeting its competitors, positioning itself as a magnet supplier as well as a reactor developer. CEO and founder Jack Zamattio puts it this way: fusion can add tens of gigawatts a year to the grid, but only if it becomes accessible and industrially replicable.
Large-scale magnet tests and the real commercial cost remain to be demonstrated. The 2030 goal is a reactor with net gain (Q>1), a metric that measures plasma energy rather than electricity output. If the New Jersey line starts on schedule, 2027 will show for the first time whether rare-earth-free HTS can withstand industrial production. Italy is following the story closely: Hephaestus has one of its offices in Rome, in a country with a well-established tradition of fusion research.
