hard-won knowledge, and they’re all about commercialization.”
Here’s a snapshot of three such companies:
COMMONWEALTH FUSION SYSTEMS, which was launched by professors
from MIT’s Plasma Physics and Fusion Research Center in 2018,
is looking for space. For the time being, CFS and MIT design and
technical teams are working in what used to be the control room
for Alcator C-Mod, an Energy Department-funded experimental
tokamak on MIT’s campus. The machine, which sits in a large bay
two doors away, ran a so-called high field using especially powerful
magnets and set a record for plasma pressure.
CFS is seeking to make the next advance in magnetic con-
finement using new, commercially available high-temperature
superconductors. The discovery of such materials was an advance
that won the Nobel Prize in Physics in 1987.
Before high-temperature superconductors became available
in the past decade, tokamak builders faced a trade-off: use a lot of
power to run a high magnetic field or run a lower magnetic field in
a much bigger device, like ITER, says Mumgaard of CFS. The new
superconductors will enable the company to build a smaller, cheaper
version of an ITER-like machine. “Two years from now, we will
have that magnet done,” he says.
CFS’s subsequent step will be to build a demonstration
machine called Sparc that will use the new magnet technology.
Sparc will be about 12 feet tall and could fit into half a tennis court.
Construction is supposed to start in 2021 and finish in 2025. A
commercial version, called Arc, is expected to follow. It would be
approximately twice as big, fitting into a basketball court.
CFS’s tokamak will burn D-T fuel, which means it will confront
the first-wall problem. The solution, Mumgaard says, is “to build a
machine so you can replace the wall very easily.” Replace it often
enough, he says, and it wouldn’t get very radioactive and could be
stored and then recycled. “You can choose what you put around the
machine,” he says. “Right now we can go with the stuff that’s cheapA plasma injector at General Fusion. Such machines are designed to shoot fusion fuel into a vortex of liquid metal where it would be compressed by pistons and ignite.
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