JET has shown record fusion performance, producing 59 megajoules (MJ) of energy from fusion reactions sustained for 5 seconds.
This builds on a past deuterium-tritium (DT) campaign from 1997. Whilst they haven't exceed the peak fusion power produced (16 megawatts (MW) in 1997, average of 11MW today) or the scientific Q value (the ratio of energy out to energy in, 0.7 in 1997, 0.33 today) they have doubled the fusion power produced in a sustained 5-second pulse.
Work on the JET tokamak has also highlighted the development of remote handling robotic capabilities, which will be critical for future commercial fusion power plants.
The scientists have more than doubled the energy output from fusion over a sustained timescale. Keeping the plasma conditions right for fusion over the longer timescale is what will be required for future power plants.
5 seconds is long time on fusion timescales. It is more than ten times the "energy confinement time", which is the time takes energy to leak out of the hot plasma. This gives confidence that this timescale can be extended on future tokamaks with superconducting magnets, such as ITER.
Additionally, this doubling in performance has been attained on the same machine as in 1997, but with upgrades to the inner wall materials, among other capabilities. This shows the importance of advancing fusion technology.