Hephaestus

Product

Hephaestus works on two components of fusion-power economics: the magnets that confine plasma and the plasma configurations that determine reactor behaviour. Its approach combines rare-earth-free high-temperature superconducting materials with negative-triangularity tokamak designs.

Founded in London in 2019 by Jack Zamattio, the company uses AI-based tools for plasma modelling and materials discovery. It completed its first negative-triangularity device, Anvil 0, in 2024 and has developed superconducting materials at laboratory scale.

Hephaestus is preparing manufacturing at a New Jersey facility and pursuing a net-gain fusion demonstration. Its planned materials business would supply superconductors to other fusion developers as well as support its own reactors; commercial-scale production and net-gain performance remain development targets.