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 Center for Fusion Energy in the English county of Oxfordshire, has a history dating back to 1975. The Culham site was chosen in 1977 and the doughnut-shaped tokamak made its first plasma in 1983 ( the Queen made the official commissioning the following year.)
In 1991, JET performed the world’s first deuterium-tritium experiment, and in 1997 achieved 22.5 megajoules of fusion energy (and 16 megawatts of fusion power) in a series of dedicated deuterium-tritium experiments. In 2021, it completed a second full-power run using deuterium and tritium.
And now here we are, at 100,000 pulses. That’s quite a feat for the experience as we approach the 40th anniversary of activation.
JET was recently shut down in order to refit it with concepts from the ITER design, including a new deuterium-tritium inner wall installed in 2011. The results of JET’s experiments will therefore inform plans for ITER, which is to come in service in the mid-2020s.
Hotter than the sun: JET – Earth’s largest fusion reactor, at Culham
However, time is running out for JET. Notwithstanding this milestone, it will be replaced by the much larger ITER tokamak currently under construction in the south of France and expected to generate its first plasma in late 2025.
The involvement of British boffins in the undertaking has been a bit uncertain, despite the background work done at JET for ITER. After all, the UK left the European Atomic Energy Community (Euratom) on January 31, 2020. However, an agreement has been reached to allow the UK to continue participating from January 1, 2021.
Professor Ian Chapman, CEO of the UK Atomic Energy Authority, paid tribute to the experience and said: “JET has inspired and challenged physicists and engineers around the world to gain invaluable knowledge and develop groundbreaking new technology with an impressive 100,000 live pulses.”, before delivering what sounded a bit like a eulogy: “It’s truly one of a kind, the best ever, and we’re will remember it long into the future.”
Regardless of how long the machine, weighing 2,800 tonnes, has been in operation for this week’s milestone remains a tribute both to its design and to the engineers and scientists who operate it. ®