The inner workings of a nuclear fusion reactor

Imagine a power plant so powerful that it’s like bringing the energy of the sun to Earth. It might sound like science fiction, but a project in southern France is working to make this a reality.

The ITER plant will be the world’s largest nuclear fusion reactor when it comes online in 2025. It’s been 35 years in the making, involves 35 participating nations, and is designed to explore using fusion as an industrial-scale source of clean energy.

At its heart, a device called a tokamak uses toroidal (doughnut-shaped) magnetic field coils to contain the plasma created by the fusion process. Each about the same size as a six-story building and weighing 6,000 metric tons, ITER’s 18 field coils are the most powerful superconductive magnets ever designed.

This animation shows the part these giant magnetic coils play in the fusion reaction that produces carbon-free energy.