The pioneering Joint European Torus (JET) has performed its final fusion research experiments just over four decades after it delivered its first pulse on June 25, 1983. The Culham, U.K.-sited facility performed its final day of plasma experiments on December 18, 2023, and delivered its 105,929th pulse.

Operated by the U.K. Atomic Energy Authority, the facility was the site of research conducted by scientists from 28 European countries. using it to conduct research into the potential for carbon-free fusion energy in the future through work coordinated by the EUROfusion consortium, which manages and funds European fusion research activities on behalf of Euratom.

Temperatures inside this tokamak system can reach levels 10 times hotter than the center of the sun. JET achieved the world’s first controlled release of fusion energy, producing its first pulse or plasma in 1983, and went on to create the first deuterium-tritium plasma in 1991, reaching a record 1.8 MW. A second set of deuterium-tritium experiments was completed in 2021, reaching a world record for sustained fusion energy at high power by producing 59 megajoules over five seconds, demonstrating fusion power plant potential.

The JET system will next enter the repurposing and decommissioning phase expected to last until about 2040.