Physics & Fusion Science
Helium Ash Transport
How fusion-produced helium moves and must be exhausted.
- Goal
- Exhaust ash, avoid dilution
Helium 'ash' from fusion must be transported to the edge and pumped out before it dilutes the fuel. Helium transport and exhaust efficiency set a limit on sustainable fusion power, tying core physics to the pumping system.
It is one reason the divertor and vacuum pumping are performance-critical, not just protective.
Common questions
Why must helium ash be removed?
The helium produced by fusion dilutes the fuel and cools the plasma if it builds up, so it must be transported to the edge and pumped out. Ash removal efficiency sets a practical ceiling on sustainable fusion power.
What removes the ash?
The divertor and cryopumps on the breeder, and the end tanks on the burner — which is why those exhaust systems are performance-critical, not merely protective.