US team claims viable path to commercial fusion power

A record-breaking superconducting magnet developed by researchers in the US could pave the way for practical, commercial, nuclear fusion.

commercial fusion power
This large-bore, full-scale high-temperature superconducting magnet has demonstrated a record-breaking 20 tesla magnetic field. It is the strongest fusion magnet in the world. Credit: Gretchen Ertl, CFS/MIT-PSFC, 2021

Experts from MIT spin-out Commonwealth Fusion Systems (CFS) and MIT’s Plasma Science and Fusion Center (PSFC) have announced the successful test of the world’s strongest high temperature superconducting (HTS) magnet, the key technology for a device that the group claims will unlock the path to clean commercial fusion energy for the world.

The test, conducted at MIT’s Plasma Science and Fusion Center, proved that the magnet built at scale can reach a sustained magnetic field of more than 20 tesla, enough to enable CFS’s compact tokamak device, called SPARC, to achieve net energy from fusion.

“This record-breaking magnet is the culmination of the last three years of work and will give the world a clear path to fusion power for the first time,” said Bob Mumgaard, CFS CEO. “The world needs a fundamentally new technology that will support efforts to decarbonize on a timeline that can mitigate climate change. This test of our magnet proves we have that technology, and we’re on our way to producing clean, limitless energy for the entire world.”

commercial fusion power
Rendering of SPARC, a compact, high-field, tokamak, currently under design by a team from the Massachusetts Institute of Technology and Commonwealth Fusion Systems. Credit: T. Henderson, CFS/MIT-PSFC, 2020

To build the magnets the team used new commercially available high temperature superconductors (HTS). While existing tokamaks rely on device scale to attempt net energy, HTS magnets enable a high-field approach that will enable CFS to reach net energy from fusion with a device that is substantially smaller, lower cost, and on a faster timeline.

“This groundbreaking magnet opens a widely identified transformational and accelerated opportunity for advancing fusion science and commercial fusion energy,” said Dennis Whyte, Director of MIT’s PSFC and CFS Co-Founder.

Tokamaks are donut-shaped devices that use magnets to control and insulate a plasma in which fusion occurs. While no fusion device has yet to achieve net energy from fusion, tokamaks have come the closest with more than 160 tokamaks built and successfully operated around the world.

In the past, tokamaks used low-temperature superconducting magnets that required them to be enormous in size to create the magnetic field needed to attempt to achieve net energy. CFS HTS magnets will enable significantly stronger magnetic fields and as a result significantly smaller tokamaks.

This HTS magnet technology will next be used in SPARC, which is under construction in Devens, Massachusetts and on track to demonstrate net energy from fusion by 2025. SPARC will pave the way for the first commercially viable fusion power plant called ARC. “This is the fastest path to commercialization of affordable fusion energy across the globe,” said Mumgaard.