"There’s one aspect of the current fleet of magnetic fusion machines that is holding back progress. It’s a lesson that has been learned time and time again in fusion: . . . fusion works best on big scales. For conventional tokamaks, the confinement of plasma gets better the bigger the machine is. . . . When it is completed, ITER will be the world’s largest tokamak, and one of its key objectives will be to demonstrate net energy gain. It’s a behemoth. . . . ITER will take up 180 hectares (equivalent to 250 soccer fields), and when finished, its structure will have a mass equivalent to three Eiffel Towers."