The Joint European Torus (JET) facility at the Culham Centre for Fusion Energy in the UK has achieved a significant milestone in fusion energy production. In a late 2021 experiment, the results of which were announced in February 2022, the device generated 59 megajoules of heat energy from a sustained fusion reaction lasting five seconds. This achievement more than doubles the previous fusion energy record of 21.7 megajoules, also set at JET in 1997. The experiment operated with an average power output of approximately 11 megawatts (thermal) for the duration of the pulse. This result provides critical validation for the operational scenarios and plasma physics models underpinning the next-generation ITER project currently under construction in France. Source: The Independent

The record-setting pulse was achieved within JET's tokamak, a toroidal magnetic confinement device. The experiments utilized a deuterium-tritium (D-T) fuel mixture, the most reactive fuel cycle for fusion and the one planned for ITER and most commercial power plant designs. A key objective of this experimental campaign was to test the performance of materials and components under reactor-relevant conditions. The inner wall of the JET vessel was constructed with a beryllium and tungsten lining, mirroring the material choices for ITER's divertor and first wall. The ability to sustain a high-power D-T plasma for five seconds without significant material degradation or plasma instability is a crucial demonstration of these materials' viability and the robustness of the operating scenario. Source: The Independent

The record-setting pulse was achieved within JET's [tokamak](/glossary/tokamak), a toroidal magnetic confinement device.

This result is not a demonstration of net energy gain, as the energy required to heat the plasma and operate the facility's systems far exceeded the 59 megajoules produced. The primary scientific goal was to sustain a high-performance plasma for a multi-second timescale, which is a fundamental requirement for future power plants. The five-second duration was limited by the operational constraints of JET's copper-based magnetic field coils, which are not actively cooled and heat up during a pulse. In contrast, ITER will employ superconducting magnets capable of maintaining stable magnetic fields for hundreds or thousands of seconds, enabling much longer plasma durations and the potential to achieve a net energy gain, or Q > 1. Source: The Independent

The experiments at JET serve as a direct dress rehearsal for ITER, providing essential data for validating plasma control schemes, heat exhaust management, and neutronics codes. According to the UK Atomic Energy Authority (UKAEA), which operates the facility on behalf of the EUROfusion consortium, the successful campaign confirms the physics basis for ITER's planned operation. The ability to replicate and then exceed the 1997 performance in a machine with a different wall configuration demonstrates a mature understanding of the complex physics involved. These results will be used to finalize ITER's research plan and operational procedures, reducing the risks associated with its first D-T campaign. The achievement is a major update for the public fusion program's confinement records. Source: The Independent