Fusion Power Density

Fusion power density rises steeply with magnetic field and pressure — the physics that lets a high-field compact tokamak rival a much larger one.

Scales as

≈ β² · B⁴ (pressure² · field⁴)

Implication

Field is the strongest single lever

Kronos field

24.6 T peak conductor

Payoff

Gigawatt-class power from a 5.75 m machine

Fusion power density — how much fusion power a cubic metre of plasma produces — is what decides whether a reactor can be compact. It scales roughly as the square of the plasma pressure and, because pressure is limited by beta times field, as the fourth power of the magnetic field. Doubling the field, in principle, can raise power density sixteenfold.

This steep scaling is the entire rationale for the high-field approach. Kronos MetroVolt's 24.6 T peak conductor field is what lets a machine of modest size — a 5.75 m major radius — target gigawatt-class fusion power, where an older low-field design would need to be far larger. Field is the most powerful single lever a fusion designer has, which is why the magnet is the enabling technology.