UK scientists advance nuclear fusion with stable high plasma pressure
A major achievement at the MAST Upgrade experimental facility located in the United Kingdom offers a promising path to overcoming one of the biggest hurdles in commercial nuclear fusion. Researchers have managed to generate plasma at high pressure while maintaining its stability, an essential feat for sustainable energy production.
The United Kingdom marks another significant step towards applicable nuclear fusion. The team of scientists operating the MAST Upgrade reactor achieved the highest level of plasma pressure ever documented at the facility, while ensuring that the material remained in controlled conditions.
The United Kingdom Atomic Energy Authority (UKAEA) released this discovery following the completion of the fifth MAST Upgrade trial campaign. The tests, carried out between 2025 and 2026, resulted in the production of more than 1,100 fusion plasmas, consolidating the data obtained.
This advancement is of particular relevance as future fusion-based power plants will need to operate under extreme conditions, including extremely high temperatures, pressures and densities, while keeping the plasma under strict control.
Nuclear fusion, a process that naturally occurs on the Sun, is being replicated on Earth by scientists. They heat hydrogen isotopes to colossal temperatures to form plasma, an extremely hot, electrically charged state of matter.
To increase the efficiency and productivity of fusion reactions, it is essential that the fuel reaches high temperatures and densities, and is effectively confined within the reactor.
Pressure is a crucial factor in this process. High-pressure plasmas have the potential to generate more fusion energy in a smaller volume, which is critical for the development of commercial reactors. However, increasing plasma pressure traditionally leads to a major challenge: instability.
One of the most serious problems arising from this instability is known as Edge Localized Mode, or ELM.
Learn more: China verifies density-free regime in EAST tokamak and advances nuclear fusion
ELMs, or Extreme Energy Level Modulations, are abrupt bursts of instability that manifest at the edges of fusion plasma. They cause the rapid release of a considerable amount of energy stored in the plasma towards the internal components of the reactor.
As reported by the UKAEA, a single ELM event can expel about a tenth of the energy contained in the plasma. The repetition of these events is capable of causing damage to the walls and exhaust components of future fusion plants, increasing maintenance costs and possibly compromising the economic viability of this energy source.
The results obtained directly influence the design of future fusion power plants.
James Harrison, head of science for MAST Upgrade at UKAEA, said: “Producing extremely hot plasma is just one part of the challenge. Scientists also need to find ways to keep this plasma in check.”
He added that “the results truly shape the design of future fusion power plants. Access to four stable, high-performance plasma regimes, including QH mode, QCE mode and I mode, plus our novel plasma position control technique, demonstrates that MAST Upgrade is producing science at the cutting edge of what is possible.”
See Also
3,600-year-old tomb discovered in Egypt reveals king of lost dynasty
Virginia Fonseca leaves Grande Rio to focus on new businesses: ‘Ready for one more’
Humanoid robots will compete in new disciplines at the Beijing World Games
Harrison also highlighted that “the level of international interest in our data reflects the UK’s central role in global fusion research, and these findings bring us even closer to practical fusion energy.”
The most recent experiments carried out at MAST Upgrade confirm that plasma stability can be maintained even when internal pressure increases.
The MAST Upgrade team investigated a number of advanced operating regimes. The objective was to suppress or mitigate instabilities that could cause damage.
Full coverage: Latest News (EN)
Among the tested approaches, Quasi-Continuous Exhaustion (QCE) and Resonant Magnetic Perturbations (RMP) stand out. Furthermore, two additional regimes were explored: Quiescent Mode H (QH mode) and Mode I.
These strategies aim to improve plasma confinement and reduce the harmful effects associated with large ELMs. The experiments proved that the MAST Upgrade can operate in four stable, high-performance plasma regimes under conditions that are relevant to next generations of fusion machines.
The importance of these findings transcends the experiment itself. The ultimate goal is to create operational methods that can be applied to reactors designed for large-scale electricity generation.
One of the most notable advances was the development of an innovative method to detect and adjust the plasma position in real time, in an automated way.
The MAST Upgrade team used measurements of the visible light emitted by deuterium in the divertor area of the machine. By analyzing this luminosity, the researchers were able to identify small changes in the position of the plasma.
The relevance of this technique goes far beyond simple experimental monitoring. Future commercial fusion plants will rely on highly sophisticated automated control systems capable of responding to variations in plasma in an agile and precise manner.
A power plant will not be able to depend on constant manual interventions by scientists to adjust each parameter. Real-time automated control will be an essential requirement to ensure continuous and reliable operation.
Follow: all about Clean Energy
However, keeping the plasma stable is only part of the complexity. A fusion reactor also needs to manage extraordinary amounts of heat and particles expelled during the process.
In the MAST upgrade experiments, the use of nitrogen at the edges of the plasma was investigated. The researchers observed that the introduction of small amounts of this gas can cause a significant portion of the exhaust energy to be released in the form of light, making it easier to deal with excessive heat.
