Practical nuclear fusion milestone achieved, higher plasma pressure feat recorded

The United Kingdom Atomic Energy Authority announced a major achievement at the MAST Upgrade fusion facility where scientists recorded the highest plasma pressure ever achieved on the machine while maintaining stability. The breakthrough came during the facility's fifth experimental campaign which ran through 2025 and 2026 and produced more than 1,100 fusion plasmas. The experiments demonstrated access to four stable high-performance plasma regimes including QH-mode QCE and I-mode. Researchers also developed a world-first plasma position control technique using visible light measurements from deuterium in the divertor region to detect tiny positional imbalances in real time. James Harrison head of MAST Upgrade Science at UKAEA said the results genuinely shape the design of future fusion power plants and demonstrate the UK's central role in global fusion research. The findings take researchers another step closer to practical fusion energy. Future commercial fusion plants will need to operate at extremely high temperatures pressures and densities while maintaining precise control. The MAST Upgrade experiments showed this can be achieved even as plasma pressure is pushed higher. Researchers also found that adding small quantities of nitrogen at the plasma edge can cause a large proportion of exhaust power to be emitted as light.