After 40 years of major milestones in nuclear fusion, the Joint European Torus (JET) facility finally closed its doors in December 2023, not without one final record-breaking achievement. On Thursday, representatives of the revolutionary tokamak reactor confirmed its latest experiment generated 69.26 megajoules of energy in just five seconds. That's more than 10 megajoules more than JET's previous world record, and more than triple its first-ever peak power level of 22 megajoules in 1997.
[Related: The world’s largest experimental tokamak nuclear fusion reactor is up and running.]
Located in Oxfordshire, United Kingdom, the JET Reactor Facility began operations in 1983 with the hope of bringing the world closer to sustainable and economically viable fusion production. While fission emits massive amounts of energy by splitting atoms, fusion involves breaking apart atoms such as tritium and deuterium at temperatures above 150 million degrees Celsius to create helium plasma, a neutron and ridiculous amounts of energy. The sun – and all other stars, by extension – are essentially gigantic celestial nuclear fusion reactors, so imitating even a fraction of that type of energy here on Earth could revolutionize the energy industry.
The first one tokamakThe reactor, an acronym for “toroidal chamber with magnetic coils”, entered service in the USSR in 1958. Tokamaks resemble a huge, very high-tech tire filled with hydrogen gas which is then spun at high speed using a magnetic winding . The force of its rotations around the chamber then ionizes the atoms into helium plasma.
Although there are many facilities around the world that can produce nuclear fusion reactions, it is still extremely expensive. JET's December record, for example, reached its record energy level in just five seconds, but those 69 megajoules were still enough to warm the water in a few bathtubs.
Even the most optimistic realists estimate that it could take another 20 years (at very at least) before affordable fusion energy is a viable option. Others, meanwhile, argue that useful fusion reactors will never be a financially feasible solution. It currently costs hundreds of thousands of dollars to simply fire up a fusion reactor, let alone maintain its processes indefinitely – neither of which can do, since the technology is not yet available. Moreover, the current climate emergency cannot wait for a solution in two decades or more. But if society ever makes fusion reactors a real, sustainable alternative, it will be largely thanks to everything JET has accomplished over its four decades of service.
Talk with the BBC On Thursday, Britain's Minister for Nuclear and Networks, Andrew Bowie, called the final JET experiment a “swan song” for the reactor that pushes the world “closer than ever to fusion energy.”
With JET permanently shut down, the world's largest fusion reactor is now Japan's six-story JT-60SA tokamak located north of Tokyo. Although inaugurated in December 2023, if all goes as planned, the JT-60SA will not retain the title for long. Its European brother, the International Thermonuclear Experimental Reactor (ITER), should be commissioned in 2025, although this project has not been without difficulties and delays.