Scaling high-temperature superconducting magnets for compact magnetic confinement

REBCO and YBCO tapes rewrite tokamak scaling laws — Energy Singularity's HH70 hits a 22 T peak field and a 1,337-second pulse.

The integration of Rare-Earth Barium Copper Oxide (REBCO) and Yttrium Barium Copper Oxide (YBCO) high-temperature superconducting materials has fundamentally altered the scaling laws of magnetic confinement fusion. By operating optimally at roughly 20 Kelvin, these magnets generate immense magnetic fields that drastically reduce the required major radius of a tokamak to achieve net energy gain.

Commonwealth Fusion Systems validated this approach by demonstrating a 20 Tesla field strength with their HTS electromagnet. The result, first published in 2021 and re-benchmarked on full-scale SPARC coils last week, has been the central reference point for the compact-tokamak thesis adopted across the private sector.

Energy Singularity's HH70 — the world's first all-HTS tokamak — has now extended the envelope, achieving a steady-state plasma operation of 1,337 seconds using a central solenoid with a record 22 Tesla peak field. The Shanghai-based developer says the result is a key data point for the EXL-50U follow-on machine targeting burning-plasma conditions later this decade.