Major and Minor Radius

R0 of 1.2 m and a minor radius near 0.48 m set Hyperion's size: a machine you can stand beside, not a stadium-scale reactor.

Setting the scale

Two lengths define a tokamak plasma. The major radius R0 is the distance from the machine's central axis to the center of the plasma cross-section; for Hyperion it is 1.2 m. The minor radius a is the half-width of the plasma cross-section; at aspect ratio 2.5 that is about 0.48 m. Together they describe a compact torus that fits in a modest hall.

Why compact

Hyperion is sized to a neutron and isotope supply requirement, not to a megawatt rating. A smaller plasma volume with strong field and high current reaches the neutron flux the blanket needs without the scale of a gigawatt power tokamak. Compactness also keeps the first-of-a-kind build tractable and shortens the path from construction start in Q2 2027 to first tritium near 2030.

Volume and surface

A plasma of R0 1.2 m and a 0.48 m, elongated vertically, encloses a modest volume but presents a substantial first-wall area for its size. That surface is where the 14 MeV neutron flux crosses into the blanket. The compact geometry concentrates that flux, which is favorable for breeding productivity per unit but demanding on materials, and it is one reason the center post carries a limited lifetime.

• R0 1.2 m; minor radius a ~ 0.48 m
• Sized to neutron supply, not to electrical output
• Compactness aids schedule and flux density, stresses materials

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.