The world’s largest nuclear fusion project has entered its five-year assembly phase.
After this is finished, the facility will be able to start producing the super-hot “plasma” required for fusion power.
The £ 18.2bn (€ 20bn; $ 23.5bn) facility is under construction in Saint-Paul-Lez-Durance, southern France.
Advocates say fusion can be a source of clean, unlimited power that will help combat climate crises.
It is a collaboration between China, the European Union, India, Japan, South Korea, Russia and the US. All members share the cost of construction.
Current nuclear power depends on fission, where a heavy chemical element splits to make it lighter.
On the other hand, nuclear fusion works by combining two light elements to form a heavier one.
It releases large amounts of energy with very little radioactivity.
The etter will confine hot plasma within a structure called a tomacum to control fitter reactions.
The project will help demonstrate whether fusion can be commercially viable. French President Emmanuel Macron said the effort would unite countries around a good country.
The facility can see the plasma generated in the machine – an early start to operations shortly after the assembly phase ends in 2025.
President Macron said: “Iter is clearly an act of confidence in the future. The greatest progress in history has always proceeded with courageous bets, a journey filled with difficulty.
“At the beginning it always seems that there will be more than the will to create obstacles and progress. Iter relates to this sense of discovery, of ambition, with the idea that, thanks to science, tomorrow can actually be better than tomorrow is.”
But fusion power has its own skepticism. It is difficult to make it commercially viable because scientists have struggled to get enough energy from the reactions.
Advocates believe that Itter can overcome technical barriers and, while facing planetary challenges, fusion is worth the expense and effort.
The UK is a member of the Iter project, but is set to fall out, as the British government withdrew from a major treaty as part of Brexit. The UK can stay only when a new way is found to maintain its participation until the end of the Brexit transition.
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