DOE and MIT Are Working on a Nuclear Fusion Reactor

This novel reactor that could make nuclear fusion commercially viable.
Christopher McFadden

The U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) is working with the private industry to develop a cutting-edge project to make nuclear fusion commercially viable. The device, called "SPARC" is being developed through a spinoff startup, Commonwealth Fusion Systems, from MIT.


The "SPARC" of inspiration

The project hopes to nail down the problem of leakage of "alpha particles" that are generated by nuclear fusion reactions from reactors like that used by the "SPARC" project. The project is a part public, part privately funded project that makes use of DOE grants to support their efforts to develop high-performance fusion grade plasmas using a tokamak-type reactor.

SPARC fusion reactor
Conceptual image of the "SPARC" reactor. Source: Steve Jurvetson/Flickr

However, such reactors can suffer from misalignments of superconducting magnets used to confine fusion plasma. This leads to the leakage of vital "alpha particles" that can slow or even halt the production of fusion energy, as well as, damage the interior of the reactor -- not ideal, to say the least.

The key to mitigating this problem is to use specially designed superconducting magnets and make the reactor more compact in size, so the team behind the "SPARC" project believes. By reducing the size of the reactor and using better magnets, the reactor should be able to operate at higher fields and stresses than existing reactors. 

This should also enable the design and construction of smaller and less-expensive fusion facilities. This, however, assumes that fast alpha particles created in fusion reactions can be contained long enough to keep the plasma hot.

"Our research indicates that they can be," PPPL physicist Gerrit Kramer said. Kramer is a key participant in the project through the DOE Innovation Network for Fusion Energy (INFUSE) program.

"We found that the alpha particles are indeed well confined in the SPARC design," explained Kramer, coauthor of a paper in the Journal of Plasma Physics that reports the findings. 

Kramer came to this conclusion thanks to a very special piece of computer code called SPIRAL. This was developed by the PPPL to verify particle confinement with the reactor. 

SPARC tokamak reactor
JET tokamak reactor. Source: aglet/Flickr

"The code, which simulates the wavy pattern, or ripples, in a magnetic field that could allow the escape of fast particles, showed good confinement and lack of damage to the SPARC walls," Kramer explained.

"The SPIRAL code agreed well with the ASCOT code from Finland. While the two codes are completely different, the results were similar," said Kramer.

"SPARC" is looking very promising indeed

The findings gladdened the study's lead author Steven Scott (a consultant to Commonwealth Fusion Systems and former long-time physicist at PPPL), "It's gratifying to see the computational validation of our understanding of ripple-induced losses," he said."

"Since I studied the issue experimentally back in the early 1980s for my doctoral dissertation," he added.

Nuclear fusion is one of the "holy grails" of energy generation that, once harnessed, has the potential to provide massive amounts of energy from a small amount of fuel. For this reason, scientists around the world are working tirelessly to enable mankind to create our own, near unlimited, source of power.

SPARC decom tokamak
Decommissioned tokamak reactor at the Canadian Science Museum in Ottawa. Source: Doug Zwick/Flickr

Projects like "SPARC" are taking us one step closer to this seemingly impossible task. 

You can read the original paper in the Journal of Plasma Physics.

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