A new superconducting magnet breaks the magnetic field strength records and opens the door to practical, commercial, and carbon-free power.

This was an event that took three years to create. It was the result of intensive research and design work. On September 5, a high-temperature superconducting electromagnetic magnet was elevated to 20 teslas. It is the strongest magnetic field ever created on Earth. According to the project leaders at MIT and the startup company Commonwealth Fusion Systems, this demonstration helped resolve the most significant uncertainty in building the first fusion power station that can produce more energy than it uses.

This advancement opens the door to the long-awaited creation of affordable, practical, and carbon-free power plants, which could significantly contribute to limiting global climate change’s effects.

“Fusion in many ways is the ultimate source of clean energy,” Maria Zuber, MIT’s vice-president for research and E. A. Griswold Professor of Geophysics. “The power available to create fusion energy is truly game-changing.” Water is the fuel for fusion energy. It’s up to us to find out how to use it.

Developing the new magnet is the most significant technological hurdle in making this happen. Its successful operation now allows the possibility of demonstrating fusion at an Earth lab, which has been attempted for many decades but with little success. The MIT-CFS partnership is now on track to create the first fusion device capable of creating and containing plasma that consumes more energy than it produces. SPARC is the name of the demonstration device. It will be completed in 2025.

Dennis Whyte, director of MIT’s Plasma Science and Fusion Center, works with CFS to create SPARC and says that fusion is complex because of technical and scientific challenges. He says that once the technology has been proven, it will be an inexhaustible source of carbon-free energy that can be deployed anywhere. It is an entirely new source of energy.

Whyte is the Hitachi America Professor in Engineering. He says this week’s demonstration addresses the most critical questions about the SPARC design. He says, “It’s a historic moment in fusion science technology.”

The sun in a glass

The sun’s power comes from the process of fusion, which is when two tiny atoms are combined to create a larger one. This results in a tremendous amount of energy. The process is complicated because it requires temperatures far higher than any material can withstand. It is necessary to capture the sun’s power source on Earth by suspending it so that it does not come into contact with any solid.

This is done by intense magnetic fields that form an invisible container to hold the hot, swirling soup of electrons and protons known as plasma. The magnetic fields are strong enough to control the electric charge of the particles. The most popular configuration is the tokamak, a donut-shaped device. While most of these devices were made from copper-based electromagnets, the ITER version, which is the largest, produces its magnetic fields with what are called low-temperature superconductors.

The MIT-CFS fusion design features a significant innovation: high-temperature superconductors. These allow for a stronger magnetic field in a smaller area. The commercial availability of new superconducting material made this design possible. It was initially developed as a class project in Whyte’s nuclear engineering class. It seemed so promising that the idea was developed in the following few iterations. This led to the ARC power station design concept in early 2015. SPARC is half the size of ARC and serves as a test bed to demonstrate the image before the construction of ARC’s full-size power-producing plant.

To create the powerful magnetic fields required to heat plasma to hundreds of millions of degree Celsius, one had to increase their size. The new high-temperature Superconductor material is a flat ribbon-like material that can achieve a greater magnetic field in a smaller device. This equals the performance of an apparatus 40 times larger using conventional low-temperature magnets. This revolutionary design of ARC is based on the principle that power outweighs size.

Using high-temperature superconducting magnetic magnets makes it possible to draw on decades of experimentation from tokamak experiments (including MIT’s Alcator series). Zach Hartwig is the principal investigator at MIT and the Robert N. Noyce Career Developer Assistant Professor of Nuclear Science and Engineering. The new design scales down the existing structure to half its size and achieves the same operational conditions due to the magnetic field.

Last year, a series of scientific papers outlined the physical foundation and, through simulation, confirmed the viability of the new fusion device. If the magnets work as expected, the fusion system should produce net power output for the first time since decades of fusion research.

Martin Greenwald is the deputy director and senior research scientist at the PSFC. He says that, unlike other designs for fusion experiments, “the niche we were filling was conventional plasma physics and conventional tokamak design and engineering, but bring in this new magnet technology.” We only required innovation in a dozen different areas. We would invent on the magnet and then use the knowledge accumulated over the past decades.”

Combining scientifically proven design principles with game-changing magnetic field strength allows plants to be economically viable and develop quickly. Bob Mumgaard is the CEO of CFS. “We now have an innovative platform that’s both scientifically advanced and commercially very attractive, thanks to decades of research. He said that the magnet demonstration allows us to make devices smaller and more cost-effectively.

The proof is in the pudding.

Three years of intense work were required to bring that new concept of magnets to life. Supply chains and manufacturing methods developed for magnets that could eventually be manufactured in the thousands were established.

“We created a unique superconducting magnet. It was a challenging task to develop unique manufacturing processes and equipment. CFS’s head of operations, Joy Dunn, says that SPARC production is now in good hands. “We started with a physical model and a computer-aided design. We then developed prototypes and built manufacturing facilities to make the actual magnet. This helped them to reach the required specifications, for which CFS is the largest user.

She says they worked with two different magnet designs simultaneously, and both met the design requirements. She says, “It came to which one would revolutionize how we make superconducting magnetics and which one was simpler to build.” This design stood out to her.

The new magnet was slowly powered up over a series of steps to reach the 20-tesla goal. This is the highest-ever field strength for a high-temperature superconducting magnet. Each of the 16 plates that make up the interest is stacked together.

Mumgaard says that three years ago, we had announced a plan to build a 20-tesla magnetic, which will be needed for future fusion machines. That goal was achieved on time, even with the pandemic.

Brandon Sorbom is the chief science officer of CFS and cites a series of physics papers published last year. He says, “The papers conclude that if you build the magnet, all of the Physics will work in SPARC.” This demonstration answers the question, “Can they build the magnet?” It’s an exciting time. It’s a significant milestone.

Next, SPARC will be built. This is a smaller version of the ARC power station. SPARC’s successful operation will prove that building a commercial-scale fusion power station is possible. This will allow for the rapid design and construction that can be done at full speed.

Zuber stated that SPARC could achieve net positive energy based on its demonstrated performance with the magnets. Next is scaling up and building an actual power plant. Still, many challenges lie ahead. Not least, developing a design that can sustain reliable operation is one of them. The goal is to commercialize the power plants. Another major challenge will cost. How can you design power plants that are cost-effective to build and maintain?

Zuber believes that one day, in a future where there are thousands of fusion power plants, Zuber will say, “I think it’s going to be looking back and thinking about how we got here, and I think the demo of the magnet technology was the moment when I believed that we can achieve this.”

Zuber points out that creating a fusion device capable of producing power would be an incredible scientific achievement. But that’s not all. “We are not trying to win any trophies at the moment. We want to make the planet liveable.