Key facts
- Fusion combines light atoms into heavier ones, releasing energy — the process that powers stars
- Fusion fuel must be heated above 100 million degrees and confined long enough to sustain the reaction
- Three machine families compete: tokamaks, stellarators and inertial confinement
The hard part is control
Fusion is the reaction that combines light atoms into heavier ones and releases a huge amount of energy — the same process that powers the stars. The physics is not the obstacle; the engineering is. The fuel has to be heated to extreme temperatures, above 100 million degrees, and held there long enough for the reaction to keep going.
Three families of machines are chasing that goal, and they solve the same puzzle in very different ways.
Tokamak: the magnetic donut
Tokamaks use a donut-shaped chamber and strong magnets to keep hot plasma suspended away from any material wall. They are the most studied approach — ITER, the largest science experiment on Earth, is a tokamak — and they hold most of the field's performance records.
Stellarator and inertial confinement
Stellarators twist the chamber and the magnetic coils themselves, trading engineering complexity at construction time for calmer, more stable plasma at run time. Inertial confinement takes the opposite route entirely: no sustained confinement at all, just laser pulses compressing tiny fuel pellets to fusion conditions for a fraction of a second, many times per second.
Each approach solves the same puzzle differently. All three are chasing net energy, stable operation, and a design that can eventually scale into a power system.
What it means for the grid
None of these machines will replace a gigawatt of baseload this decade. But private capital, public programmes and grid operators are now planning around fusion as an eventual arrival rather than a perpetual promise — and the confinement race above will decide which design gets there first.
Questions
- What is nuclear fusion?
- Fusion combines light atoms into heavier ones, releasing far more energy per reaction than fission. It is the process that powers the sun and other stars.
- What is the difference between a tokamak and a stellarator?
- Both confine plasma magnetically. A tokamak uses a symmetric donut-shaped chamber and drives current through the plasma; a stellarator twists the chamber and coils themselves so the plasma stays stable without a driven current.
- Has fusion produced net energy?
- Laser-driven inertial confinement has demonstrated scientific gain at the target — more fusion energy out than laser energy in. No approach has yet delivered sustained net electricity to a grid.
Sources
- Fusion energy basics — IAEA
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