Divertor Heat Exhaust

Spreading, radiating, and detaching the exhaust plasma keeps divertor target heat flux within material limits in a compact machine.

The scale of the load

A large fraction of the power that crosses the plasma edge is ultimately deposited on the divertor targets, concentrated onto a narrow strip. Left unmanaged, the resulting heat flux would exceed what any solid surface can survive continuously. Managing this exhaust is among the hardest engineering problems in tokamak design and is sharper in a compact machine with little divertor room.

Strategies

Three levers reduce target loading. Geometry lengthens and tilts the strike region to spread power over more area. Impurity seeding makes the divertor plasma radiate its energy volumetrically before it reaches the plates. Detachment cools the plasma near the target until it no longer contacts the surface at full energy. Real designs combine all three to hold flux within limits.

Coupling to the core

Exhaust cannot be optimized in isolation: radiating too hard or detaching too far can cool the plasma edge enough to hurt core confinement, while too little cooling overloads the targets. The divertor operating point must sit in the window that protects the surfaces without spoiling the confinement that sustains Q_sci 3.076. Finding and holding that window at Hyperion's compact scale is exercised in simulation and is a target of the first-of-a-kind tests.

• Target heat flux otherwise exceeds material limits
• Spreading, radiation, and detachment reduce the load
• Exhaust and core confinement must be balanced together

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.