Magnetic vs inertial confinement
The two dominant routes to fusion. One holds a thin plasma steady for seconds; the other crushes a fuel capsule in nanoseconds. They are not measured with the same yardstick, which is where most confusion starts.
Magnetic confinement
Doughnut-shaped magnetic confinement using a strong toroidal field plus a current driven through the plasma itself. The most-studied configuration, and the one ITER uses.
87 devices · 26 organisations · 425 measurements
Inertial confinement
Compressing fuel so fast that its own inertia holds it together long enough to burn — nanoseconds, not seconds.
8 devices · 10 organisations · 6 measurements
The differences that matter
| Magnetic confinement | Inertial confinement | |
|---|---|---|
| How confinement works | Magnetic fields hold a low-density plasma continuously. | A driver implodes a fuel capsule; its own inertia confines it for nanoseconds. |
| Density and duration | Low density, long duration — seconds to minutes. | Extreme density, durations measured in nanoseconds. |
| How gain is quoted | Plasma gain: fusion power over external heating power coupled into the plasma. | Target gain: fusion yield over laser energy delivered to the target. These denominators are not interchangeable. |
| What has been achieved | JET released 69.26 MJ in a single pulse; no device has exceeded plasma gain of 1. | NIF exceeded target gain 1 in December 2022, reaching 1.5. |
| The comparison trap | A magnetic device quoting plasma gain is counting heating power only. | An inertial device quoting target gain excludes the laser system’s own vast inefficiency. Same shot, wall-plug gain 0.0077. |
Read this before comparing. Comparing a target gain to a plasma gain is comparing two different fractions. See the gain page. More on that here.
Devices in this dataset
Magnetic confinement 87
- Joint European Torus · 12
- Experimental Advanced Superconducting Tokamak · 11
- KSTAR · 11
- ITER · 10
- DIII-D · 9
- ASDEX UPGRADE · 9
- ST40 · 9
- JT-60U · 9
- SPARC · 9
- Wendelstein 7-X · 8
- GLOBUS-M2 · 7
- Tokamak Fusion Test Reactor · 6
- NOVA-FURG · 5
- ETE · 5
- and 73 more
Inertial confinement 8
Organisations
Magnetic confinement 26
Commonwealth Fusion SystemsEnergy SingularityENN Science and Technology DevelopmentGauss FusionGeneral AtomicsHelical FusionHelion EnergyInstitute of Plasma Physics, Chinese Academy of SciencesITER OrganizationKorea Institute of Fusion EnergyMaritime FusionMax Planck Institute for Plasma PhysicsNational Institute for Fusion ScienceNovatron Fusion GroupNT-TaoProxima FusionRealta FusionRenaissance FusionStartorus FusionStellarex EnergySTEPTAE TechnologiesThea EnergyTokamak EnergyType One EnergyUK Atomic Energy Authority