Researchers at the Joint European Torus (JET) facility have achieved a new world record for sustained fusion energy, generating 59 megajoules from a five-second plasma pulse. The experiment, conducted by the EUROfusion consortium at the UK Atomic Energy Authority's Culham site, used a deuterium-tritium (D-T) fuel mixture and demonstrated an average fusion power of approximately 11 MW. This result more than doubles the previous fusion energy record of 21.7 megajoules set at JET in 1997. The successful campaign validates key physics models and provides critical operational data for the next generation of fusion devices, most notably the international ITER project. Source: Independent

The recent experiments at JET are significant not only for the energy produced but also for their direct relevance to ITER's design and operational plan. JET was upgraded with a new inner wall made of beryllium and tungsten, materials identical to those specified for the much larger ITER tokamak under construction in France. Operating with a D-T fuel cycle in this ITER-like wall environment for the first time since the late 1990s provides crucial data on plasma-wall interactions, fuel retention, and material performance. According to UKAEA CEO Ian Chapman, the results are the clearest demonstration in a quarter of a century of the potential for fusion energy to deliver safe and sustainable low-carbon power. Source: Independent

The recent experiments at JET are significant not only for the energy produced but also for their direct relevance to ITER's design and operational plan.

Achieving a sustained reaction for five seconds is a key operational milestone. While the duration was limited by the thermal capacity of JET's copper magnets and not by plasma instabilities, it represents a stable, high-power operating point. This duration is significant because it is the timescale over which heat transfer and other plasma processes reach a steady state, allowing for reliable extrapolation to the longer pulse durations planned for ITER and future power plants. The ability to maintain the plasma's stability and confinement under these conditions confirms that the chosen operational scenarios are robust, a critical step in de-risking the multi-billion-euro ITER program. Source: Independent

While the 59 MJ output is a scientific record, it is important to contextualize the net energy balance. The experiment consumed more energy to heat the plasma and run the facility than it produced, meaning the engineering gain (Q_engineering) was less than one. The primary goal was to validate the physics of a sustained, high-power D-T plasma in an ITER-relevant environment, not to achieve net energy gain, a feat for which JET was never designed. The data gathered from these pulses will now be used to refine the operational plans for ITER, which is specifically designed to be the first fusion experiment to produce a net energy gain, targeting a Q_plasma of 10. Source: Independent