Aviation Week was given an exclusive story on Lockheed Martin, the largest defense contractor in America, having developed what they say is the first realistic design for a small fusion reactor capable of powering everything from an airplane to a city. If true, this is a monumental development.
Although the company released limited information on the CFR in 2013, Lockheed is now providing new details of its invention. Aviation Week was given exclusive access to view the Skunk Works experiment, dubbed “T4,” first hand. Led by Thomas McGuire, an aeronautical engineer in the Skunk Work’s aptly named Revolutionary Technology Programs unit, the current experiments are focused on a containment vessel roughly the size of a business-jet engine. Connected to sensors, injectors, a turbopump to generate an internal vacuum and a huge array of batteries, the stainless steel container seems an unlikely first step toward solving a conundrum that has defeated generations of nuclear physicists—namely finding an effective way to control the fusion reaction.
“I studied this in graduate school where, under a NASA study, I was charged with how we could get to Mars quickly,” says McGuire, who earned his Ph.D. at the Massachusetts Institute of Technology. Scanning the literature for fusion-based space propulsion concepts proved disappointing. “That started me on the road and [in the early 2000s], I started looking at all the ideas that had been published. I basically took those ideas and melded them into something new by taking the problems in one and trying to replace them with the benefits of others. So we have evolved it here at Lockheed into something totally new, and that’s what we are testing,” he adds…
The CFR will avoid these issues by tackling plasma confinement in a radically different way. Instead of constraining the plasma within tubular rings, a series of superconducting coils will generate a new magnetic-field geometry in which the plasma is held within the broader confines of the entire reaction chamber. Superconducting magnets within the coils will generate a magnetic field around the outer border of the chamber. “So for us, instead of a bike tire expanding into air, we have something more like a tube that expands into an ever-stronger wall,” McGuire says. The system is therefore regulated by a self-tuning feedback mechanism, whereby the farther out the plasma goes, the stronger the magnetic field pushes back to contain it. The CFR is expected to have a beta limit ratio of one. “We should be able to go to 100% or beyond,” he adds.
This crucial difference means that for the same size, the CFR generates more power than a tokamak by a factor of 10. This in turn means, for the same power output, the CFR can be 10 times smaller. The change in scale is a game-changer in terms of producibility and cost, explains McGuire. “It’s one of the reasons we think it is feasible for development and future economics,” he says. “Ten times smaller is the key. But on the physics side, it still has to work, and one of the reasons we think our physics will work is that we’ve been able to make an inherently stable configuration.” One of the main reasons for this stability is the positioning of the superconductor coils and shape of the magnetic field lines. “In our case, it is always in balance. So if you have less pressure, the plasma will be smaller and will always sit in this magnetic well,” he notes.Overall, McGuire says the Lockheed design “takes the good parts of a lot of designs.” It includes the high-beta configuration, the use of magnetic field lines arranged into linear ring “cusps” to confine the plasma and “the engineering simplicity of an axisymmetric mirror,” he says. The “axisymmetric mirror” is created by positioning zones of high magnetic field near each end of the vessel so that they reflect a significant fraction of plasma particles escaping along the axis of the CFR. “We also have a recirculation that is very similar to a Polywell concept,” he adds, referring to another promising avenue of fusion power research. A Polywell fusion reactor uses electromagnets to generate a magnetic field that traps electrons, creating a negative voltage, which then attracts positive ions. The resulting acceleration of the ions toward the negative center results in a collision and fusion.
The team acknowledges that the project is in its earliest stages, and many key challenges remain before a viable prototype can be built. However, McGuire expects swift progress. The Skunk Works mind-set and “the pace that people work at here is ridiculously fast,” he says. “We would like to get to a prototype in five generations. If we can meet our plan of doing a design-build-test generation every year, that will put us at about five years, and we’ve already shown we can do that in the lab.” The prototype would demonstrate ignition conditions and the ability to run for upward of 10 sec. in a steady state after the injectors, which will be used to ignite the plasma, are turned off. “So it wouldn’t be at full power, like a working concept reactor, but basically just showing that all the physics works,” McGuire says.
Now I’m certainly no physics expert (and I’d love to hear from those who are), but I’m giving this a lot more credibility than the usual cranks working in their garages who claim to have produced cold fusion and the like. This is a huge corporation that has spent a massive amount of money on this research and they know how bad it would be for them to announce such a breakthrough if they weren’t pretty certain it would work.
But there are still potential problems. The physics may turn out to be wrong, for instance. Or the actual material development of the units might end up being either impossible or far too expensive (though the latter seems unlikely). Still, if this technology becomes a reality it will mean a revolution in how we generate energy and would dramatically reduce our use of fossil fuels, which can only be a good thing.