MetroVolt's toroidal field is 6.37 T at the plasma axis but 24.42 T at the innermost conductor — exactly the demonstrated single-coil field — and that peak is carried by REBCO high-temperature superconducting tape, engineered with the margins published line by line.
The magnet system winds 183.1 MA-turns using roughly 33,200 km of REBCO tape at the operating field. Peak on-conductor field is 24.42 T at the critical radius R_c = 1.50 m — the 24.4 T single-coil field already demonstrated publicly, and below the 26 T design allowable. Hoop stress lands at 593 MPa against a 900 MPa yield basis (a 1.5× margin) using distributed-structure design, and the preload architecture is bladder-and-key, adapted from LHC-generation accelerator magnet practice.
This is the deposited field lever (S78) made real: the ratified Mode-D basis (24 July 2026) adopts the lever at its build limit — R_c = 1.50 m, B₀ = 6.37 T — landing the peak on the demonstrated single-coil field while raising the on-axis field that pays for the near-thermal operating output.
Magnets are the pacing technology of compact fusion, and the difference between a claim and a plan is whether the peak field, stress, quench, and fatigue lines are written down against demonstrated anchors. MetroVolt's are — including the honest note that 24.42 T is demonstrated at single-coil, not yet full-system, scale: the remaining gap is configuration, not field level.
| Peak on-conductor field | 24.42 T at R_c = 1.50 m |
| Demonstrated anchor | 24.4 T (single coil) — matched by the adopted S78 lever |
| Total conductor | ≈33,200 km REBCO tape · 183.1 MA-turns |
| Hoop stress | 593 MPa vs 800 allowable |
| Fatigue basis | >10⁴ full-field ramp cycles (30-yr life) |