The history of JET

  • 1975
    Proposals for the JET machine are completed
  • 1977
    Culham in Oxfordshire is chosen as the host site for JET
  • 1983
    JET is turned on achieving its first plasma
  • 1984
    JET is officially opened by Her Majesty The Queen
  • 1991
    JET performs the world’s first deuterium-tritium experiment – the fuel mix that will be used in the first commercial fusion power plants
  • 1997
    JET achieves a world record of 22.5 megajoules of fusion energy and 16 megawatts of fusion power in the first dedicated deuterium-tritium run of experiments. This proves large amounts of power can be produced from fusion
  • 2021
    Completes a second full-power run of experiments using deuterium and tritium
  • 2022
    JET's 100,000th pulse is completed
  • 2022
    New record-breaking JET results are announced. The machine achieves 58 megajoules of sustained fusion energy

The Joint European Torus (JET) is the largest and most powerful tokamak in the world. Weighing 2,800 tonnes, the same as 14 blue whales, JET is operated by UKAEA in Oxfordshire, with experiments run by researchers from the EUROfusion consortium – 4,800 experts, students and staff from across Europe, co-funded by the European Commission.


JET is the only tokamak – a machine which confines a plasma using magnetic fields – in the world running experiments using deuterium and tritium, isotopes of hydrogen. It has been key to the development of its successor ITER, a larger and more advanced version of JET. ITER is based in France and is one of the biggest collaborative science projects in history, involving 35 nations.


ITER, which is expected to come into operation in the mid-2020s, plans to operate under conditions similar to those used by JET and will continue working towards demonstrating the scientific and technological feasibility of fusion energy.


Fusion energy is crucial in addressing climate change as a safe, sustainable and green energy supply. The fusion process brings together atoms of light elements, like hydrogen, at high temperatures to form helium and release tremendous amounts of energy as heat.


Fusion, the process that powers the sun and stars, promises a near-limitless green electricity source for the long term but is one of the biggest scientific and engineering challenges of them all.

Front cover: HRH The Prince of Wales visits UKAEA