The sixth poloidal field coil, known as PF6, of the International Thermonuclear Experimental Reactor has been inserted into the fusion machine’s tokamak pit, a milestone that marks the beginning of assembly of Iter’s magnet system, which will control the shape and stability of the reactor’s plasma.

“It’s a milestone of symbolic importance… because it paves the way for the assembly and insertion of the rest of the Iter coils," said Alessandro Bonito-Oliva, magnets programme manager at Fusion for Energy (F4E), the organisation administering Europe’s contribution to Iter said.