Researchers at the Joint European Torus (JET) facility in Culham, UK, announced a new world record for fusion energy output on February 9. The tokamak generated a total of 59 megajoules of heat energy from a sustained deuterium-tritium (D-T) fusion reaction lasting five seconds. This performance corresponds to an average fusion power of 11 megawatts during the pulse. The result more than doubles the previous energy record of 22 megajoules, also set at JET in 1997, demonstrating significant progress in maintaining stable, high-performance plasmas over longer durations. The experiments were conducted by the EUROfusion consortium, which comprises 4,800 experts from across Europe, and represent the culmination of JET's second and final D-T experimental campaign before its scheduled decommissioning. Source: Nature

This achievement serves as a critical validation for the design and operational plan of the much larger ITER project under construction in France. JET is currently the only operational tokamak capable of using the D-T fuel mix that ITER will employ. Furthermore, JET's inner vessel wall is lined with beryllium and tungsten, the same materials chosen for ITER, making these experiments a direct dress rehearsal for the conditions expected in the next-generation machine. The five-second duration of the plasma was not limited by plasma instabilities but by the technical constraints of JET's conventional copper magnets, which begin to overheat. This demonstrates that the plasma physics of the high-power, sustained scenario are sound, a crucial data point for de-risking ITER's future operations. Source: Nature

This achievement serves as a critical validation for the design and operational plan of the much larger [ITER](/programs/iter) project under construction in France.

The experiment achieved a plasma energy gain, or Q_plasma, of 0.33. This means that for the 33 megawatts of external power used to heat the plasma, 11 megawatts of fusion power were produced. While this is below the breakeven point of Q=1, the primary goal of this experimental campaign was not to set a Q record but to demonstrate sustained energy production in an ITER-relevant regime. The 1997 JET experiments achieved a higher peak power of 16 MW and a transiently higher Q of 0.67, but for a much shorter duration. The recent result's significance lies in its combination of high power and extended duration, pushing the boundaries of sustained plasma control and heat management within the device. Source: Nature

The data gathered from this record-setting pulse and the wider experimental campaign are invaluable for the fusion community. They will be used to calibrate and verify the complex computer models that predict the behavior of ITER's plasma. Confirming that these models accurately reflect real-world D-T plasma performance at this scale gives scientists and engineers greater confidence in their projections for ITER, which is designed to produce 500 MW of fusion power from 50 MW of heating power (Q=10). As JET's operational life concludes, the focus of the international public fusion program shifts decisively to the assembly and commissioning of ITER, which will build directly upon the scientific and engineering legacy established by these final experiments. Source: Nature