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Joint European Torus celebrates 100,000 pulses: Neither Brexit nor middle age has stopped '80s era experiment

Fusion energy projects nearing 40th anniversary

A milestone was reached this week by the Joint European Torus (JET): the 100,000th pulse of the fusion energy experiment.

JET, which is located at the Culham Centre for Fusion Energy in the English county of Oxfordshire, has a history going back to 1975. The Culham site was chosen in 1977 and the doughnut-shaped tokamak achieved its first plasma in 1983 (the Queen did the official switching on duties the following year.)

In 1991 JET performed the world's first deuterium-tritium experiment and by 1997 it achieved 22.5 megajoules of fusion energy (and 16 megawatts of fusion power) in a dedicated deuterium-tritium run of experiments. In 2021 it completed a second full-power run using deuterium and tritium.

And now here we are, at 100,000 pulses. It is quite the achievement for the experiment as it approaches the 40th anniversary of activation.

In 2011, JET installed a new inner wall made of beryllium and tungsten metals, the same materials to be used in its international successor, ITER. JET was recently shut down in order to refit it with concepts from the ITER design. The results of JET's experiment runs will therefore inform plans for ITER, which is due to start operation in the mid-2020s.

JET interior photo UKAEA

Hotter than the Sun: JET – Earth’s biggest fusion reactor, in Culham


However, the clock is ticking for JET. Milestone notwithstanding, it will be succeeded by the much larger ITER Tokamak, currently under construction in southern France and due to generate its first plasma at the end of 2025.

The involvement of British boffins in the endeavor has been a little uncertain, despite the groundwork being done at JET for ITER. After all, the UK left the European Atomic Energy Community (Euratom) on 31 January 2020. However, an agreement was reached to allow the UK to keep participating from 1 January 2021.

Professor Ian Chapman, CEO of the UK Atomic Energy Authority, paid tribute to the experiment, and said: "JET has inspired and driven physicists and engineers across the world to build invaluable knowledge and develop ground-breaking new technology through a staggering 100,000 live pulses," before delivering what sounded a little like a eulogy: "It is truly one of a kind, the best there has been, and will be remembered long into the future."

Regardless of how much longer the machine, weighing in at 2,800 tonnes, will be operated, this week's milestone remains a tribute to both its design and the engineers and scientists that run it. ®

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