Joint European Torus

The Joint European Torus stands beside the Culham Centre for Fusion Energy in Oxfordshire. It is the world’s largest tokamak, a doughnut-shaped machine that holds hot plasma in magnetic fields. Built between 1978 and 1982, the Torus Hall still houses the experiment today. The machine began operations in 1983 and was opened by Queen Elizabeth II the following year. Scientists from across Europe run the project, testing how plasma behaves under fusion conditions. JET was designed to reach scientific breakeven, where fusion power equals heating power. JET’s record-breaking run in 1997 brought it closest to that goal. It produced 16 megawatts of fusion power from 24 megawatts of heating, giving a Q value of 0.67. This stood as the world record until 2021. In 1991 JET became the first reactor to use a real fusion fuel mix of tritium and deuterium. Engineers also installed a divertor to remove waste from the plasma, improving performance. These advances shaped later designs for the international ITER project in France. Visitors walk into the Torus Hall to see the massive machine through viewing windows. Inside, the tokamak’s copper coils and vacuum vessel are clearly visible. The remote-handling system, developed at Culham, lets engineers swap components without entering the vessel. Outside, the Culham site includes laboratories and offices where fusion research continues. The experiment closed in December 2023, but decommissioning will take until 2040.