Vacuum Pumping System
Pumps establish and hold the high vacuum the plasma needs and remove unburned fuel and helium ash from the divertor.
Two vacuum jobs
The vacuum system does two things. Before operation it evacuates the vessel to the high vacuum a plasma requires, removing air and outgassed contaminants. During operation it continuously removes the gas load: unburned deuterium and tritium, helium ash from fusion, and any impurities, mostly through the divertor where exhaust is concentrated.
Coupled to fueling and tritium
Because only a small fraction of injected fuel is burned per pass, the pumps handle a large throughput of unburned tritium. That exhaust is not waste: it is separated, and the tritium is recovered and returned to the fueling system. The vacuum system is therefore the front end of the tritium recycling loop, and its efficiency affects how much tritium inventory the machine must hold at any time.
Helium removal
Helium ash is the spent product of fusion; if it accumulates it dilutes the fuel and cools the reaction. The vacuum system, working with the divertor, exhausts helium so the burn stays clean, and part of that helium stream connects to the machine's helium-3 accounting. Pumping speed, tritium compatibility, and reliable operation in an activated environment are the practical design drivers for this system.
- Establishes and maintains high vacuum for the plasma
- Removes unburned D-T and helium ash via the divertor
- Front end of tritium recovery and recycling
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.