esterday, defense contractor Lockheed Martin announced that they were working on a compact nuclear fusion reactor. That wasn’t much of a surprise—the company’s Skunk Works division is probably investigating lots of similar pie-in-the-sky technologies. Rather, the surprise was that Lockheed claimed they could have proof-of-concept prototypes working within five years and a functional reactor in ten. A 100 megawatt version, they added, would be as big as a small ranch home and use just 55 pounds of fuel per year.
And last week, a team from the University of Washington led by physicist Thomas Jarboe announced their “dynomak,” a new take on the classic tokamak reactor design, could be cheaper than coal. Inside the dynomak, a spheromak chamber would contain the superheated plasma required to create a self-sustaining fusion reaction. While the dynomak is expected to be larger than Lockheed’s compact fusion reactor (CFR) project, they say a one gigawatt version could be built for $100 million less than an equivalent coal-fired power plant.
Both proposals take use magnets to confine the plasma, similar to the massive International Thermonuclear Experimental Reactor, or ITER, that’s being built in France. ITER plans on containing the plasma within a more traditional tokamak, or donut shaped chamber. That reactor won’t be ready for testing until 2027.
Details on the Lockheed CFR proposal are sparse, but according to a simple figure they released, their confinement chamber does away with the tokamak in favor of a design that looks like a child’s top laid on its side. Two superconducting magnets, each placed a quarter of the way in from the spindle-like ends, generate the magnetic fields that would control the plasma. The key, according to project lead Tom McGuire, is how the magnetic fields react when plasma presses deep into them. He told Kathleen Palmer at Wired:
“If we have a perturbation or a ripple that sends it closer to the wall, the magnetic field gets stronger and stronger, so it has the right kind of feedback to keep it stable,” McGuire says.
Based on publicly-released information, the University of Washington team appears to be a step ahead of Lockheed. They have constructed a small-scale version of their reactor, called HIT-Si3, which can produce power, albeit far less than is required to start the reaction. Lockheed, on the other hand, has only built a small prototype to confirm their plasma confinement capabilities. They don’t appear to have any power-producing prototypes.
Lockheed’s announcement has made headlines for their ambitious timetable—a prototype in five years and a full-scale reactor in ten. That has made some scientists skeptical, including competitor Jarboe. “I would have to study their scientific publications on the confinement claim to see if their data justifies the claim. I have not seen the papers, but the nuclear engineering clearly fails to be cost effective,” he wrote in a comment at Aviation Week. Swamesh Mahajan, a plasma physicist at the University of Texas, was similarly doubtful, questioning the materials science behind the project. He told James West of Mother Jones, “We know of no materials that would be able to handle anywhere near that amount of heat.”
It’s easy to be cynical about nuclear fusion announcements. Full-scale reactors always seem to be 20 years away. But given these two announcements in the last two weeks—one from a major research university, another from a large defense contractor—along with continuing work at the ITER and the National Ignition Facility, there may be reason to hope that commercially-viable nuclear fusion could happen in the near future.