MetroVolt's toroidal field is 6 T at the plasma axis but 24.6 T at the innermost conductor — and that peak is carried by REBCO high-temperature superconducting tape, engineered with the margins published line by line.
The magnet system winds 172.6 MA-turns using roughly 31,300 km of REBCO tape. Peak on-conductor field is 24.6 T at the critical radius R_c = 1.40 m — just above the 24.4 T single-coil field already demonstrated publicly, and below the 26 T design allowable. Hoop stress lands at 604 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.
The deposited field lever (S78) adds a purchased insurance policy: moving the winding-pack centre to R_c = 1.44 m while re-rating to B₀ = 6.11 T holds the peak at exactly the demonstrated 24.4 T — inside the 0.42 m of spare radial build, with fusion power unchanged and Troyon/kink margins improved.
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 24.6 T is demonstrated at single-coil, not yet full-system, scale.
| Peak on-conductor field | 24.6 T at R_c = 1.40 m |
| Demonstrated anchor | 24.4 T (single coil); S78 lever reaches it |
| Total conductor | ≈31,300 km REBCO tape · 172.6 MA-turns |
| Hoop stress | 604 MPa vs 900 yield (1.5×) |
| Fatigue basis | >10⁴ full-field ramp cycles (30-yr life) |