UK Scientists Achieve Key Advance in Nuclear Fusion Control
CULHAM, UK – Scientists at the UK Atomic Energy Authority (UKAEA) have announced a notable breakthrough in controlling the volatile plasma within spherical tokamaks – a crucial step towards practical nuclear fusion energy. Experiments at the MAST-U (Mega Amp Spherical Tokamak Upgrade) facility have successfully suppressed Edge Localized Modes (ELMs), bursts of energy and particles that can damage fusion reactors, for the first time in this type of device.
ELMs are a persistent challenge in fusion research. Researchers describe them as “tantrums” of the superheated plasma,and have now demonstrated techniques to “teach their bottled sun better manners.” Previous ELM suppression was achieved in larger, doughnut-shaped tokamaks, with the DIII-D machine in California demonstrating the technique nearly two decades ago.
However, MAST-U’s success marks the first instance in a spherical tokamak, a more compact and potentially cost-effective design favoured by Britain for its future prototype fusion plant, STEP (Spherical Tokamak for Energy Production). While spherical tokamaks offer advantages in performance per cubic meter, their magnetic fields are inherently more complex to manage.
“Suppressing ELMs in a spherical tokamak is a landmark achievement,” said James Harrison, head of MAST-U science at UKAEA. “It is an important demonstration that advanced control techniques developed for conventional tokamaks can be successfully adapted to compact configurations.”
the plasma within MAST-U reaches temperatures exceeding 35 million °C – more than twice the temperature of the sun’s core.Alongside ELM suppression, the team also achieved independent control of the machine’s upper and lower divertors, the exhaust ports responsible for managing heat and particles after the hydrogen fuel is spent. This independent control is vital to prevent plasma from contacting the reactor walls, which would cause damage and halt the fusion reaction.
“I’m delighted with the ground-breaking findings from our team at UKAEA,” stated Fulvio Militello, executive director of plasma science and fusion operations at UKAEA. “These achievements reinforce the UK’s leadership in fusion research and bring us closer to realising fusion as a clean, safe, and abundant energy source for the future.”
The findings from MAST-U are expected to directly inform the growth of STEP,planned for completion in the 2040s.While acknowledging that harnessing fusion remains a complex undertaking,researchers express cautious optimism that these advancements are building a compelling case for its future viability.
