Take a look behind the scenes at the world’s largest fusion experiment

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine. — The 30-metre-deep assembly pit for the tokamak

©enrico sacchetti

Extreme in scale and ambition, this is ITER, the €20-billion energy project being built in southern France. It is set to pave the way to fusion power, akin to that which fuels the sun.

Work started on the world’s biggest fusion experiment in 2006 through an international effort, including the European Union, the US, China and Russia. The first run of the reactor, during which it will create superhot matter known as plasma – a state necessary for nuclear fusion to occur – was scheduled for 2020. This was first pushed back to 2025, and fresh delays have now postponed it to 2035.

Meanwhile, exclusive photographs taken by Enrico Sacchetti offer a glimpse into ITER’s construction and potential.

The main image shows the size involved, with a 30-metre-deep assembly pit for the tokamak, a device responsible for confining spiralling plasma to a doughnut-shaped torus using magnetic fields. Pictured above is a shot of one of the toroidal coils that produce these fields.

The below images show some of the nine sectors that make up the ITER vacuum vessel. This weighs 5200 tonnes and provides a highly resilient “cage” for experiments, ensuring that continuously spiralling plasma doesn’t touch its walls.

The image above shows part of the vacuum vessel being transported for repairs, while the below shots show supports lining the wall of blanket modules that shield the structure and magnets from the heat and high-energy neutrons of the reactions.