US fusion energy startup Realta Fusion in partnership with researchers from the University of Wisconsin (UW) have applied the highest ever steady magnetic field in a fusion plasma experiment. Using the Wisconsin HTS Axisymmetric Mirror (WHAM) experiment, researchers formed and held a plasma with an applied magnetic field strength of 17 Tesla on the confined plasma achieving a series of firsts for fusion energy. This demonstration was the first use of High Temperature Superconductor (HTS) magnets in a magnetic mirror configuration.
Magnetic Confinement Fusion (MCF) creates the conditions for fusion to occur by trapping a very energetic plasma in a “magnetic bottle”. WHAM is the first device to integrate HTS magnets with multiple high power plasma heating systems and advanced plasma control. By combining these innovations, the WHAM experiment is expected to achieve new records in plasma density, paving the path to commercial fusion energy.
“This is the culmination of a huge effort from the WHAM team, and a significant step towards fusion energy power plants,” said Professor Cary Forest of the University of Wisconsin and Chief Scientific Officer of Realta Fusion. “With the WHAM experiment we have brought together advances in superconductor technology and plasma physics, to demonstrate the potential of the compact magnetic mirror as a fusion energy system.”
The magnetic mirror was a leading fusion energy concept in the US until the 1980s but the available technology was a limiting factor to controlling the magnetically confined plasma. Recent advances in superconducting technology – specifically HTS magnets – and plasma stability control encouraged the collaborators to revisit the magnetic mirror and design a much more compact and lower cost system than earlier experiments.
“Today’s demonstration puts the compact magnetic mirror firmly back in the race towards commercial fusion energy. It’s a giant leap forward for a concept that promises economically viable, zero-carbon heat and electricity,” said Realta Fusion CEO Kieran Furlong.
Realta Fusion is a venture-backed private fusion company spun out of the WHAM project in 2022. Realta continues to fund and staff the ongoing WHAM project through a sponsored research agreement with the University of Wisconsin. The US Department of Energy Advanced Research Projects Agency–Energy (ARPA-E) invested over $10m in the project, along with significant contributions from the University of Wisconsin, WARF, Commonwealth Fusion Systems (CFS) and other partners. CFS designed and manufactured the two 17 T axisymmetric HTS magnets used in the experiment. Realta Fusion raised a seed financing round in May 2023 led by Khosla Ventures and is an awardee of DOE’s Milestone Fusion Programme.
