A Small, Modular, Efficient Fusion Plant
August 10, 2015 | MITEstimated reading time: 5 minutes
![](https://iconnect007.com/application/files/1316/3116/9122/fusion_plant.jpg)
It’s an old joke that many fusion scientists have grown tired of hearing: Practical nuclear fusion power plants are just 30 years away — and always will be.
But now, finally, the joke may no longer be true: Advances in magnet technology have enabled researchers at MIT to propose a new design for a practical compact tokamak fusion reactor — and it’s one that might be realized in as little as a decade, they say. The era of practical fusion power, which could offer a nearly inexhaustible energy resource, may be coming near.
Using these new commercially available superconductors, rare-earth barium copper oxide (REBCO) superconducting tapes, to produce high-magnetic field coils “just ripples through the whole design,” says Dennis Whyte, a professor of Nuclear Science and Engineering and director of MIT’s Plasma Science and Fusion Center. “It changes the whole thing.”
The stronger magnetic field makes it possible to produce the required magnetic confinement of the superhot plasma — that is, the working material of a fusion reaction — but in a much smaller device than those previously envisioned. The reduction in size, in turn, makes the whole system less expensive and faster to build, and also allows for some ingenious new features in the power plant design. The proposed reactor, using a tokamak (donut-shaped) geometry that is widely studied, is described in a paper in the journal Fusion Engineering and Design, co-authored by Whyte, PhD candidate Brandon Sorbom, and 11 others at MIT. The paper started as a design class taught by Whyte and became a student-led project after the class ended.
Power plant prototype
The new reactor is designed for basic research on fusion and also as a potential prototype power plant that could produce significant power. The basic reactor concept and its associated elements are based on well-tested and proven principles developed over decades of research at MIT and around the world, the team says.
“The much higher magnetic field,” Sorbom says, “allows you to achieve much higher performance.”
Fusion, the nuclear reaction that powers the sun, involves fusing pairs of hydrogen atoms together to form helium, accompanied by enormous releases of energy. The hard part has been confining the superhot plasma — a form of electrically charged gas — while heating it to temperatures hotter than the cores of stars. This is where the magnetic fields are so important—they effectively trap the heat and particles in the hot center of the device.
While most characteristics of a system tend to vary in proportion to changes in dimensions, the effect of changes in the magnetic field on fusion reactions is much more extreme: The achievable fusion power increases according to the fourth power of the increase in the magnetic field. Thus, doubling the field would produce a 16-fold increase in the fusion power. “Any increase in the magnetic field gives you a huge win,” Sorbom says.
Tenfold boost in power
While the new superconductors do not produce quite a doubling of the field strength, they are strong enough to increase fusion power by about a factor of 10 compared to standard superconducting technology, Sorbom says. This dramatic improvement leads to a cascade of potential improvements in reactor design.
The world’s most powerful planned fusion reactor, a huge device called ITER that is under construction in France, is expected to cost around $40 billion. Sorbom and the MIT team estimate that the new design, about half the diameter of ITER (which was designed before the new superconductors became available), would produce about the same power at a fraction of the cost and in a shorter construction time.
But despite the difference in size and magnetic field strength, the proposed reactor, called ARC, is based on “exactly the same physics” as ITER, Whyte says. “We’re not extrapolating to some brand-new regime,” he adds.
Another key advance in the new design is a method for removing the the fusion power core from the donut-shaped reactor without having to dismantle the entire device. That makes it especially well-suited for research aimed at further improving the system by using different materials or designs to fine-tune the performance.
In addition, as with ITER, the new superconducting magnets would enable the reactor to operate in a sustained way, producing a steady power output, unlike today’s experimental reactors that can only operate for a few seconds at a time without overheating of copper coils.
Liquid protection
Another key advantage is that most of the solid blanket materials used to surround the fusion chamber in such reactors are replaced by a liquid material that can easily be circulated and replaced, eliminating the need for costly replacement procedures as the materials degrade over time.
“It’s an extremely harsh environment for [solid] materials,” Whyte says, so replacing those materials with a liquid could be a major advantage.
Right now, as designed, the reactor should be capable of producing about three times as much electricity as is needed to keep it running, but the design could probably be improved to increase that proportion to about five or six times, Sorbom says. So far, no fusion reactor has produced as much energy as it consumes, so this kind of net energy production would be a major breakthrough in fusion technology, the team says.
The design could produce a reactor that would provide electricity to about 100,000 people, they say. Devices of a similar complexity and size have been built within about five years, they say.
“Fusion energy is certain to be the most important source of electricity on earth in the 22nd century, but we need it much sooner than that to avoid catastrophic global warming,” says David Kingham, CEO of Tokamak Energy Ltd. in the UK, who was not connected with this research. “This paper shows a good way to make quicker progress,” he says.
The MIT research, Kingham says, “shows that going to higher magnetic fields, an MIT speciality, can lead to much smaller (and hence cheaper and quicker-to-build) devices.” The work is of “exceptional quality,” he says; “the next step … would be to refine the design and work out more of the engineering details, but already the work should be catching the attention of policy makers, philanthropists and private investors.”
The research was supported by the U.S. Department of Energy and the National Science Foundation.
Suggested Items
Trouble in Your Tank: Materials for PWB Fabrication—Drillability and Metallization
07/16/2024 | Michael Carano -- Column: Trouble in Your TankLaminate materials are the building blocks on which printed circuit boards are manufactured. Circuit board designers rely on the critical electrical properties of the materials to design the interconnects, and with the drive toward IoT (internet of things), autonomous driving, and virtual and augmented reality, material properties take on a very high level of importance.
Beyond Prepreg: The Glassless ‘Revolution’
06/25/2024 | Marcy LaRont, PCB007 MagazineAs our industry rallies around the call to action for HDI and UHDI, we find unparalleled and myriad laminate options. This abundance is rivaled only by the question surrounding them: Can they measure up to the high technology packaging demands required in our near future? Unsurprisingly, recent developments in FR-4-esque materials for high-speed and high-density designs, as well as newer, glassless technology for replacing traditional glass-impregnated laminates and prepreg, are garnering much interest. I caught up with Alun Morgan, technology ambassador for Ventec International Group, to ask about the impending “glassless revolution” and how it’s poised to solve some of our manufacturing challenges.
Connect the Dots: Designing for Reality—Lamination and Materials
06/19/2024 | Matt Stevenson -- Column: Connect the DotsAs many of you have likely figured out, I am quite passionate about the subject of designing PCBs for the reality of manufacturing. I wrote a book about it and I participate in an I-Connect007 On the Line with… podcast series dedicated to the subject. This companion article will focus on multilayer lamination, keeping the bigger picture in mind: Realistic PCB designs should prioritize manufacturability and reliability of the PCB as well as meet the other design requirements. So, one must account for the production variables associated with individual manufacturing partners.
Day 2: A Full Day at the EIPC Summer Conference
06/19/2024 | Pete Starkey, I-Connect007Editor's note: This is the third and final report from the EIPC Summer Conference. It was a bright and early start to the second day of the 2024 EIPC Summer Conference at the European Space Centre, Noordwijk, The Netherlands, June 4-5. A short journey by bus from the hotel in Leiden and our security passes from the day before got us through the gate and to our seats in the Newton Room for Session 4, “Material Studies,” moderated by Martyn Gaudion.
Looking Into Space: EIPC Summer Conference, Part 2
06/17/2024 | Pete Starkey, I-Connect007“Innovative Development of PCB Technology and Design” was the theme of the second session of the 2024 EIPC Summer Conference, June 4-5, at the European Space Centre, Noordwijk, The Netherlands.