This week, researchers at the University of Wisconsin-Madison and their spinoff company, Realta Fusion, have reached a record milestone and a significant step forward in attaining the persistent goal of nuclear fusion, first plasma. Following a long effort, the Wisconsin HTS Axisymmetric Mirror experiment now successfully achieved “first plasma” upon crossing a significant threshold on July 15.
The magnetic mirror confinement concept came to the fore in the 1980s but lost great interest because of its rival concept, the toroidal tokamaks. It is now re-invigorated with High-Temperature Superconductor improvements. Using superconducting magnets to create a “magnetic bottle” to trap high-energy plasma could make the technique more efficient and economical for fusion energy.
The prospects for decarbonizing our energy sector are just so much better with fusion than anything else, Cary Forest said. He is a key figure in the development of WHAM. “First plasma is important for us to take the first step in that direction.”
Design-wise, WHAM is deceivingly simple: it consists of a cylinder chamber flanked by two electromagnets. Charged particles of those isotopes travel in a helical path along this cylinder, and when they encounter a strong enough magnetic field, they reverse motion, increasing the probability of fusion. This yields a neutron and an alpha particle, the latter of which is caught by dish-shaped direct energy converters.
“Current fusion projects are taking too long, they’re too capital intensive, and they’re too complex,” said Kieran Furlong, Co-Founder of Realta Fusion. “Realta is developing a reactor that will be a much better fit in terms of time, capital, and risk for the early adoption of fusion energy.”
The WHAM experiment has already set a world record for confining a plasma with a magnetic field strength of 17 Tesla, the highest ever on a fusion plasma experiment. The accomplishment is due to the close collaboration with Commonwealth Fusion Systems, which manufactured the HTS magnets used in the experiment.
“This is the culmination of a huge effort from the WHAM team, and a significant step towards fusion energy power plants,” Forest continued. “Work on the WHAM experiment at MIT has combined advances in superconductor technology and plasma physics to successfully demonstrate the potential of the compact magnetic mirror as a fusion energy system.”
Good feel for numbers: Realta Fusion has racked up a serious list of supporters, which rounds up to more than $10M in funding from the U.S. Department of Energy’s Advanced Research Projects Agency–Energy, better known as ARPA-E. The company also closed a seed financing round in May 2023, led by Khosla Ventures.
“Today’s demonstration puts the compact magnetic mirror firmly back in the race towards commercial fusion energy,” Furlong said. “It’s a giant leap forward for a concept that promises economically viable, zero-carbon heat and electricity.”
It is fusion’s promise that seems most captivating when the serious quest for clean energy is being made today. Although many years away from mainstreaming the technology, such achievements lead us a step closer to the time when fusion may yield an all but boundless and clean energy source.
In the race toward a decarbonized future, fusion energy stands as a lighthouse, hopefully, one day providing the same energy from just one gram of fuel that 11 tons of coal do, but without the carbon emissions. The more scientists push their edge of the envelope, the closer is the realization of the dream of harnessing star power here on Earth.