Power Exhaust and Detachment

Detachment radiates exhaust power before it reaches the divertor surface, lowering peak heat flux; achieving it without spoiling the core is the trick.

Radiating the heat away

Power exhaust is quantified by how much power must cross the plasma edge per unit of machine size — a figure that is unfavorable for compact, high-power machines. If all of it landed as bare heat flux on the divertor, no material could survive. The mitigation is detachment: deliberately radiating a large fraction of the exhaust power as light, in a cushion of cool, dense, partially neutral gas near the target, so that far less arrives as direct heat.

Detachment is induced by raising edge density and sometimes seeding a light impurity that radiates efficiently. Done well, it spreads and softens the heat load. Done poorly, the radiating front moves inward and cools the core, degrading confinement and the gain — so detachment must be controlled, not merely triggered.

The control coupling

Because detachment sits on a knife-edge between protecting the divertor and cooling the plasma, it is a real-time control problem as much as a physics one. Hyperion pairs the exhaust solution with active control, and the negative-triangularity edge helps by making the boundary steadier. The achievable detached operating window at Hyperion's power density is a design and validation result still being defined.

• Detachment radiates exhaust power before it reaches the target
• Induced by higher edge density and impurity seeding
• Must be controlled to avoid cooling and degrading the core

Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. No hardware net-gain is claimed before FOAK.