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Question
Why does Kronos use such a strong magnetic field?
Fusion power density rises with the fourth power of magnetic field, so a 24.6 T machine can be far more compact than a low-field one of equal output.
The high-field choice is what makes a compact high-power tokamak possible at all — the physics of power density rewards field steeply. It is enabled by REBCO magnets and detailed on the 24.6 T magnet system page.
Questions & answers
Why does field strength matter so much?
Fusion power density scales roughly as the fourth power of the magnetic field. Doubling the field can raise power density about sixteenfold, which means a high-field machine can reach the same performance in a far smaller, cheaper package. Field is the single strongest lever a fusion designer has.
How strong is the Kronos field?
6.0 tesla on axis, rising to a 24.6 tesla peak on the inboard magnet conductor — enabled by REBCO high-temperature superconductor, which stays superconducting at fields where older magnets would quench.
Is 24.6 T proven?
It sits just above the demonstrated 24.4 T single-coil field (Tokamak Energy's Demo3, 2025), so it is carried as a stated technology gap, defended by a strain clamp (0.252% vs 0.40% limit) and qualified at the G2 gate — not assumed.