The magnetic mirror fusion concept dates to the early 1950s, but decades ago it was sidelined by technical difficulties and researchers turned to tokamak fusion in their quest for confinement. Now it’s getting another look—with significantly more powerful technology—through WHAM, the Wisconsin HTS Axisymmetric Mirror, an experiment in partnership between startup Realta Fusion and the University of Wisconsin–Madison.

Just one week after the White House Office of Science and Technology Policy hosted a summit on domestic nuclear deployment, they filled a room again on June 6 for a livestreamed event cohosted with the Department of Energy to announce a new DOE fusion energy strategy and new public-private partnership programs, and to hear directly from stakeholders—including scientists, private fusion companies, investors, and end users—during panel discussions on fusion science and technology progress and the path to fusion energy commercialization.

Xcimer Energy announced June 4 that it has raised $100 million in Series A financing for a new facility in Denver, Colo., that will host a prototype laser system with “the world’s largest nonlinear optical pulse compression system.” As a private fusion developer, Xcimer wants to “extend the proven science of inertial fusion to industrial scale” with the help of that laser system and “key technologies and innovations from multiple fields.”

The Office of Fusion Energy Sciences (FES) in the Department of Energy’s Office of Science introduced a new plan—"Building Bridges: A Vision for the Office of Fusion Energy Sciences”—during a Fusion Energy Sciences Advisory Committee (FESAC) hearing on December 13, and announced that news December 14. What’s included? A plan for the DOE to “establish the steps needed to help advance fusion energy, including addressing key science and technology gaps in the supply chain and industry.” The vision is less a guiding document than a preview of DOE-FES’s near-term intentions, which include drafting a fusion science and technology road map in 2024 to shape investments for the coming decade.

Commonwealth Fusion Systems (CFS) and Tokamak Energy Inc. are the two magnetic confinement tokamak fusion developers to receive a portion of the $46 million in funding announced by the Department of Energy in late May for the first 18 months of a public-private Milestone-Based Fusion Development Program aimed at developing fusion pilot plant designs and resolving related scientific and technological challenges within five to 10 years.

Princeton Stellarators Inc. (PSI) and Type One Energy Group are two of the eight fusion developers selected by the Department of Energy in late May to receive a total of $46 million in funding to kick off a public-private Milestone-Based Fusion Development Program aimed at developing fusion pilot plant designs and resolving related scientific and technological challenges within five to 10 years. The DOE’s selections cover an array of plasma confinement concepts, including the magnetic confinement stellarators being developed by PSI and Type One more than 70 years after the stellarator was first envisioned.

Nuclear Newswire previously took a close look at two of the DOE’s picks: Realta Fusion and Zap Energy (“innovative concept”) and Focused Energy and Xcimer Energy (inertial fusion). Here, we’ll examine how PSI and Type One are engineering solutions to the fusion plasma confinement challenge. Both companies are benefiting from recent advances in computing power and high-temperature superconducting (HTS) magnets. It’s in plans for design, manufacturing, assembly, and control of their stellarators that they differ.

Focused Energy and Xcimer Energy are two of the eight fusion developers the Department of Energy selected in late May for funding under the public-private Milestone-Based Fusion Development Program, and the only developers using an inertial confinement concept. The Milestone program, announced in September 2022, was open to any fusion developer willing to undergo a competitive merit-review process, regardless of fusion confinement concept. But the prospects for inertial fusion concepts might have gotten a boost from Lawrence Livermore National Laboratory’s December 2022 achievement of scientific breakeven at the National Ignition Facility (NIF), which was announced shortly before the application window for the Milestone program closed.

Realta Fusion of Madison, Wis., and Zap Energy of Everett, Wash., are just two of the eight fusion developers selected by the Department of Energy for funding last week under the public-private Milestone-Based Fusion Development Program. They are the two companies with power plant concepts that don’t fit neatly into established fusion confinement categories. As energy secretary Jennifer Granholm said when she announced the awardees, “Some are working on more technically mature approaches like tokamaks and stellarators and laser inertial fusion, and others are working on innovative concepts with lower technical maturity like mirror and Z-pinch, which could lead to more compact and lower cost systems.”