New superconducting magnet could give ‘clear path to fusion power’

8 Sep 2021

The team working on the magnet housed at MIT. Image: Gretchen Ertl/CFS/MIT-PSFC

Researchers said they’re ‘trying to keep the planet liveable’ in the race to make sustainable fusion energy.

A team of scientists in the US has announced the successful test of a new, powerful, high-temperature superconducting (HTS) magnet. This tech could help create commercial fusion energy, a sustainable and clean source of power.

Commonwealth Fusion Systems (CFS), a Massachusetts start-up founded by MIT scientists that has raised more than $200m in funding, and MIT’s Plasma Science and Fusion Centre (PSFC) are behind this new magnet.

In the recent test at PSFC, they found that the device is capable of sustaining a magnetic field of more than 20 tesla, which they calculate is enough to enable CFS’s tokamak device to achieve net energy from fusion reactions.

While the race to generate fusion energy is taking place all over the world, no researchers have been able to get out more energy than they are putting into their devices. Methods for achieving net fusion vary, from using lasers to magnet-based stellarators.

This latest research is based around tokamaks – a cousin of the stellarator that works through a different way of treating the magnetic field.

Decade’s worth of research

A tokamak is a donut-shaped device that uses magnets to control and insulate plasma in which fusion occurs. These devices were initially conceptualised in the 1950s. While more than 160 have been built and successfully operated, none of these have achieved a net energy gain from fusion.

‘How do you design these power plants so it will be cost effective to build and deploy them?’

A limitation of these devices was the use of low-temperature superconducting magnets that needed to be huge in order to create a magnetic field strong enough. CFS said that its magnets will enable significantly stronger magnet fields, with much smaller tokamaks.

“This record-breaking magnet is the culmination of the last three years of work and will give the world a clear path to fusion power for the first time,” said Bob Mumgaard, the CEO of CFS.

“The world needs a fundamentally new technology that will support efforts to decarbonise on a timeline that can mitigate climate change. This test of our magnet proves we have that technology, and we’re on our way to producing clean, limitless energy for the entire world.”

Reactors of the future

The HTS magnet is set to be used in the group’s SPARC reactor, which is currently under construction in Devens, Massachusetts. With the goal of demonstrating net energy from fusion by 2025, Mumgaard said it represents the “fastest path” to the commercialisation of fusion energy across the globe.

Prof Maria Zuber, MIT’s vice-president for research, added: “I now am genuinely optimistic that SPARC can achieve net positive energy, based on the demonstrated performance of the magnets. The next step is to scale up, to build an actual power plant.

“There are still many challenges ahead, not the least of which is developing a design that allows for reliable, sustained operation. And realising that the goal here is commercialisation, another major challenge will be economic. How do you design these power plants so it will be cost effective to build and deploy them?”

Zuber said that while the creation of a fusion device capable of generating net energy would be an amazing scientific achievement, that wasn’t the point of the exercise. “None of us are trying to win trophies at this point,” she said. “We’re trying to keep the planet liveable.”

Sam Cox is a journalist at Silicon Republic covering sci-tech news