MAST Upgrade
MAST Upgrade is a spherical tokamak fusion device run by UKAEA in United Kingdom. It is operating. Like every fusion device built so far, it has produced no net electricity.
Achieved first plasma in October 2020 and is testing the Super-X divertor, an exhaust design intended to spread the heat load that would otherwise destroy the surfaces of a commercial machine.
The exhaust problem is the one that decides whether any tokamak can run commercially: the power density arriving at the divertor of a full-scale machine exceeds what any known material tolerates. MAST Upgrade exists to test a way around it, and its results feed directly into STEP.
| Organisation | UKAEA |
|---|---|
| Approach | spherical tokamak |
| Confinement | magnetic |
| Country | United Kingdom |
| Status | Operating |
| First plasma | 2020-10 |
| Target date | none stated |
|---|---|
| Power target | none stated |
| Energy gain target | none stated |
| Net electricity | No. no fusion device has produced any |
Fusion needs tritium, and the world's civilian stock comes mostly from CANDU fission reactors. See the fusion overview.
MAST Upgrade in context
1 of the 24 fusion projects on record use the spherical tokamak approach: 1 operating, 0 under construction, 0 planned.
Its first plasma is dated 2020-10, 6 years ago: the 11th earliest of 15 projects on record with a first-plasma date.
| Measure | MAST Upgrade | Median of all projects | Standing |
|---|---|---|---|
| First plasma | 2020 | 2015 | 11 of 15 (earliest first) |
Worked out from the entries on this site only, so a figure compares MAST Upgrade with what is recorded here, not with everything that exists. An entry with no value for a measure is left out of that measure's ranking and median.
Sources
- World Nuclear News, MAST Upgrade achieves first plasma · retrieved 2026-09-07
How these sources are used, including the corrections applied on top of them and what is deliberately left blank · download the underlying data