Divertor Design

The divertor is the machine's exhaust: it channels heat and helium ash out of the plasma and onto surfaces built to take the load.

The plasma exhaust

A burning plasma must continuously exhaust heat and helium ash without contaminating or cooling the core. The divertor does this by shaping the magnetic field so the outermost field lines are diverted onto dedicated target plates, usually at the bottom of the vessel, where escaping particles and power are deposited away from the confined plasma.

How it works

Poloidal-field coils create a magnetic null, an X-point, below the plasma. Field lines outside the last closed surface pass through this null and strike the divertor targets. Neutral gas and helium ash are pumped away there, and impurities are kept from streaming back into the core. The divertor thus controls both power exhaust and particle exhaust, including removal of the helium produced by fusion.

A hard heat-flux problem

The power funneled onto the divertor targets can approach the surface limits of any known material, so the geometry spreads and, where possible, radiates the load before it reaches the plates. In a compact machine like Hyperion the divertor volume is tight, making the exhaust problem more acute. Negative-triangularity shaping and detachment strategies are part of how the design keeps target loads survivable, and divertor performance at Hyperion's parameters is a key item for the first-of-a-kind campaign.

• Diverts scrape-off field lines onto dedicated targets
• Handles both power exhaust and helium-ash removal
• Heat flux near material limits, tighter in a compact ST

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.