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Nuclear energy

World-First Breakthroughs in Fusion Energy Research at the UK's MAST Upgrade Tokamak

Strategic Insights

— 1 min read

The UK's national fusion experiment, MAST Upgrade, has achieved two major world-first breakthroughs during its fourth scientific campaign. The researchers have successfully used small magnetic coils to stabilise instabilities in fusion plasmas within a spherical tokamak for the first time, and have also demonstrated independent control of upper and lower divertors. These advancements bring the UK closer to realising fusion as a clean, safe, and abundant energy source.

Key Takeaways:

  • For the first time in a spherical tokamak, small magnetic coils have been used to stabilise instabilities in fusion plasmas, marking a significant step forward in the development of sustainable fusion energy.
  • The achievement of independent control of upper and lower divertors in MAST Upgrade opens new capabilities for future fusion power plants.
  • The plasma shape achieved during the experiment was the best recorded within the machine, with an elongation of 2.5, which improves plasma performance.
  • The researchers have also demonstrated the ability to suppress Edge Localised Modes (ELMs) within the MAST Upgrade machine using Resonant Magnetic Perturbation (RMP) coils.
  • The findings will directly inform the design of ELM control systems for the UK's STEP Fusion programme and help to eliminate ELMs as a barrier to commercial fusion viability.
  • The experiment also set a record for power injected into its plasma, reaching 3.8 megawatts using neutral beam heating.
  • The technique of nitrogen injection at the plasma edge has shown that energy can be more evenly distributed across plasma-facing components, preventing excessive heat concentration.

Statistics:

  • 3.8 megawatts: The record-breaking power injected into the plasma using neutral beam heating.
  • 2.5: The best plasma shape elongation recorded within the machine, achieved during the experiment.
  • 20 year: The duration of MAST Upgrade's fourth scientific campaign.
  • ~2000: The number of researchers involved in the project.
  • £220 million: The investment made by the UK government in the STEP Fusion programme.

Sources:

  • "Mega Amp Spherical Tokamak (MAST) Upgrade" Press release, United Kingdom Atomic Energy Authority
  • "Fusion energy research" article, 2025, Contify.com
  • "MAST Upgrade achieves world-first plasma shape" article, MIL-OSI United Kingdom (http://milnz.co.nz/mil-osi-aggregation/), 20 October 2025.

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