The world’s biggest nuclear fusion project has entered its five-year assembly phase.
After this is finished, the facility will be able to start generating the super-hot “plasma” required for fusion power.
The £18.2bn (€20bn; $23.5bn) facility has been under construction in Saint-Paul-lez-Durance, southern France.
Advocates say fusion could be a source of clean, unlimited power that would help tackle the climate crisis.
Iter is a collaboration between China, the European Union, India, Japan, South Korea, Russia and the US. All members share in the cost of construction.
Current nuclear energy relies on fission, where a heavy chemical element is split to produce lighter ones.
Nuclear fusion, on the other hand, works by combining two light elements to make a heavier one.
This releases vast amounts of energy with very little radioactivity.
Iter will confine hot plasma within a structure called a tokamak in order to control fusion reactions.
The project will aim to help demonstrate whether fusion can be commercially viable. France’s President Emmanuel Macron said the effort would unite countries around a common good.