US nuclear fusion tests prove superconducting magnets repel neutron bombardment
A new research from MIT has resolved a critical concern about superconducting magnets used in nuclear fusion reactors.
By conducting precise experiments, they have confirmed that the feared “beam on effect” – a potential issue that could have weakened fusion magnets – is not a real risk. This breakthrough strengthens confidence in fusion technology, bringing humanity closer to realizing sustainable, limitless energy.
Superconducting magnets in fusion power
High-temperature superconducting magnets made from rare earth barium copper oxide (REBCO) play a crucial role in developing fusion power plants.
These magnets generate powerful magnetic fields that confine the extremely hot plasma needed for fusion reactions, where two hydrogen atoms combine to form helium, releasing energy.
However, early tests raised concerns that neutron radiation in a working fusion plant might reduce the ability of these magnets to carry electrical current without resistance. This critical current suppression could have potentially impacted the efficiency of fusion power plants.
The new study has now provided clear evidence that this ‘beam on effect’ is not an issue, removing a significant hurdle for the future of fusion energy.
The initial concern
During early experiments at MIT, researchers noticed a puzzling drop in the critical current of REBCO tapes when exposed to radiation similar to what they would experience in a fusion power plant. Unlike past tests, which measured magnets after radiation exposure these tests measured them in real-time while being irradiated.
The results were shocking! Critical current dropped by 30% during irradiation, raising alarms about whether fusion reactors could operate effectively.
“I remember the night we first saw it,” recalls MIT graduate student Alexis Devitre. “We were in the accelerator lab, and suddenly, the current just dropped. It was a big deal because it suggested fusion magnets might not work as expected.”
Identifying the true cause
The MIT team, led by professors Michael Short, Dennis Whyte, and Zachary Hartwig, along with their colleagues, conducted a series of carefully controlled experiments to get to the bottom of this effect.
They tested REBCO tapes under different radiation conditions and found something surprising – the suppression of critical current had nothing to do with neutron bombardment. Instead, it was caused by simple heating from the ion beam used in the experiments.
To confirm this, the researchers repeated their tests many times, collecting over a thousand data points. They compared conditions where the magnets were only heated with conditions where they were both heated and irradiated. The results were identical.
This meant that the “beam on effect” was not due to radiation damage but just temporary heating – something that would not occur in a fusion power plant where cooling systems are in place.
A step forward for fusion power
With this discovery, the research team has provided fusion power companies with valuable assurance. “Nobody really knew if it would be a problem, but now we can conclusively say that it’s not a concern,” says Short. “This finding allows companies to move forward with confidence.”
Beyond fusion power, this result is also important for other fields using REBCO magnets, such as satellite propulsion and particle accelerators.
The team is now focusing on longer-term studies to understand how these magnets hold up over years of radiation exposure, but for now, this research has eliminated a major risk factor. By proving that this problem does not exist, scientists can focus their efforts on other important challenges in making fusion energy a reality.
The study highlights the power of ruling out false concerns, allowing researchers to allocate their time and resources toward innovations that bring us closer to practical and sustainable fusion energy.