How high-temperature superconducting magnets transformed fusion reactor design in the 2020s — enabling compact, high-field devices that could achieve ITER-level performance at a fraction of the size and cost.
In September 2021, Commonwealth Fusion Systems (CFS) and MIT demonstrated a 20-tesla large-bore high-temperature superconducting (HTS) magnet — the most powerful fusion-relevant magnet ever built. Using REBCO (Rare Earth Barium Copper Oxide) tape, the magnet achieved fields far beyond what was possible with the Nb3Sn technology used in ITER (which peaks at ~12 T).[1]
The HTS magnet breakthrough triggered a wave of private fusion investment. CFS raised over $2 billion; Tokamak Energy, Type One Energy, Proxima Fusion, and others adopted HTS magnets for their designs. The ability to build smaller, cheaper fusion devices fundamentally changed the economics of fusion development — making it attractive to venture capital for the first time.[2]
REBCO tape production capacity, cost (~$20–50/kA·m), joint technology for demountable magnets, and radiation tolerance under fusion neutron bombardment are active areas of development. Several companies are building dedicated HTS tape production lines to meet fusion demand.[3]