The experiment conducted by the Joint European Torus (JET) in England has marked a significant milestone in the quest for mastering nuclear fusion, a potentially limitless clean energy source. Since 1983, the JET has been working to recreate the nuclear fusion process, similar to the one powering the Sun and other stars, aiming ultimately to make it applicable for energy production on Earth. Recently, this facility achieved a new milestone by generating the largest amount of energy ever produced in a fusion reaction, marking the end of nearly four decades of experimentation.
Interior of the Joint European Torus (JET) experimental fusion tokamak with a superimposed photo of plasma.
Credit: United Kingdom Atomic Energy Authority, courtesy of EUROfusion
In its final phase, the JET used 0.2 milligrams of fuel to maintain high fusion power for 5 seconds, producing 69 megajoules (about 65,000 BTUs) of energy. While this might seem modest, enough to power an average home for only a few minutes, this success is celebrated as a major breakthrough by the scientific community. It demonstrates the growing potential of fusion as a clean energy source, although the path to commercial application remains long.
The JET has surpassed its own records but has not beaten the efficiency record, which is the ratio of energy produced to the energy invested to initiate fusion, held by the National Ignition Facility (NIF) in California. The NIF, utilizing a different method called inertial confinement fusion, was the first to produce more energy than it consumes, achieving efficiencies close to 2.
Comparing the JET and the NIF is complex due to their distinct approaches to fusion. The JET, a tokamak, uses a magnetic field to confine a superheated plasma and initiate fusion, while the NIF targets a fuel capsule with lasers to cause compression and fuel fusion.
As the JET approaches the end of its operation, marking the end of an era, its legacy serves as the foundation for the future International Thermonuclear Experimental Reactor (ITER), scheduled for 2030. ITER aims to test and perfect tokamak technology for a new generation of fusion reactors, promising to continue advancing towards a clean and abundant energy source for humanity.