ITER: The world's largest fusion experiment

Weighing 23 000 tonnes and standing at nearly 30 metres tall, ITER will be an impressive sight to behold. This nuclear fusion reactor will sit at the heart of a 180-hectare site, together with auxiliary housing and equipment. The immense scale of ITER, Latin for "the way", will considerably outsize the largest experimental fusion reactors currently in operation — the Joint European Torus (JET) in the United Kingdom and the joint European–Japanese JT-60SA in Japan. But what is ITER's potential, and, in an era of miniaturization and optimization, why is it necessary to build a research device on such a gigantic scale? One of ITER's primary goals is to prove that fusion reactions can produce significantly more energy than the energy supplied to initiate the reaction process — resulting in an overall gain in power. Reactors like ITER are called tokamaks (see article, page 6), and use a combination of heating systems, strong magnets, and other devices to create energy-releasing fusion reactions in super-hot plasmas. The resulting magnetic fields bind and spin the charged particles around the doughnut-shaped reactor vessel so that these can fuse and produce fusion energy.