Fusion is the fundamental energy source of the universe, powering our sun and the distant stars.
The process involves light elements, such as hydrogen, smashing together to form heavier elements, like helium, releasing prodigious amounts of energy in process.
The promise of harnessing fusion energy is limitless, safe, zero-carbon energy. The problem is that the process only produces net energy at very high temperatures of hundreds of millions of degrees – too hot for any solid material to withstand. To get around that, fusion researchers use magnetic fields to hold in place the hot plasma, a gaseous soup of subatomic particles that fuels the process, to stop it melting through the metal reactor.
The ultimate goal of fusion research, yet to be achieved, is creating a fusion reactor that produces more energy than it took to ignite and contain the process.