JET (Joint European Torus)

JET (Joint European Torus) was the world's largest and most successful tokamak experiment, located at the Culham Centre for Fusion Energy (CCFE) in Oxfordshire, UK. The facility was designed in the 1970s as a collaborative European project and began operation in June 1983. JET was operated by the UK Atomic Energy Authority (UKAEA) under the EUROfusion consortium.

JET's major achievements include:

• 1983: First plasma
• 1991: First experiments with deuterium-tritium (D-T) fuel mixture, producing ~2 MW of fusion power
• 1997: D-T campaign producing 16 MW of fusion power (peak) and 22 MJ of fusion energy, setting records that stood for over 25 years
• 2021: Tritium Exhaust Processing system commissioned for final D-T campaign
• December 2023: Final D-T campaign producing 69 MJ of fusion energy over 5 seconds, setting a new world record for fusion energy output

The December 2023 record was particularly significant as it demonstrated sustained fusion power production at a level relevant for power plant design. The 69 MJ result represented a significant improvement over the 1997 record and validated key physics predictions for ITER. The campaign used a deuterium-tritium fuel mixture, the same fuel planned for ITER and future power plants.

JET was unique in being the only operational tokamak capable of working with tritium, making it an essential facility for developing tritium handling, tritium breeding, and tritium safety protocols for ITER and future fusion power plants. The tritium handling expertise developed at JET is a critical asset for the European fusion program.

JET also served as a critical testbed for ITER technologies, including:

• The ITER-like ICRH antenna
• Beryllium and tungsten plasma-facing components (the same materials planned for ITER)
• Remote handling robotics for in-vessel maintenance
• Divertor physics and exhaust management

JET was decommissioned in 2023, with the final D-T campaign serving as the culmination of 40 years of operation. The decommissioning process will take several years and involves the safe removal and disposal of activated components, including tritium-contaminated materials. The knowledge gained from JET's decommissioning will inform the decommissioning of future fusion power plants.

The JET site at Culham continues to be a major fusion research hub, hosting MAST Upgrade (MAST-U), various technology test facilities, private fusion companies (First Light Fusion, Tokamak Energy nearby), and the STEP program offices. The Culham campus is also the site of General Fusion's demonstration plant (LM26).