Peak Field 16.84 T and 8 T On-Axis

The toroidal field falls as 1/R, so a 16.84 T peak at the center-post conductor becomes 8 T on the magnetic axis — the field the plasma actually sees.

Two field numbers, one magnet

Hyperion's toroidal field is quoted two ways: a peak of 16.84 T and an on-axis value of 8 T. Both are correct and describe the same magnet. The toroidal field falls off as 1/R with distance from the machine axis, so it is highest at the inboard conductor on the center post and lower out at the plasma center.

The peak 16.84 T is what the superconducting conductor and its structure must withstand; the 8 T on-axis is what sets the plasma's confinement and fusion performance. Confusing the two overstates the field the plasma experiences, so the design keeps both explicit.

Why high field matters here

Fusion power density rises steeply with field, and confinement improves with field, so a high on-axis field lets a compact machine reach 85.0 MW. Achieving 8 T on-axis in a spherical tokamak demands 16.84 T at the center-post conductor — near the edge of what high-temperature superconductor can hold — which is why the magnet and center post are among the hardest engineering problems. The magnet gate exists to confront exactly this.

• Toroidal field ∝ 1/R: high inboard, lower on-axis
• 16.84 T peak on the conductor; 8 T on the plasma axis
• High field enables compactness but stresses the center post

This page describes a design-and-simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. No hardware net-gain is claimed before FOAK.