On September 5, 2021, researchers at MIT’s Plasma Science and Fusion Center (PSFC) reached a milestone in fusion energy research. They successfully tested a groundbreaking high-temperature superconducting magnet, achieving a record magnetic field strength of 20 tesla. This feat is a crucial step toward creating practical fusion power plants, potentially revolutionizing the future of energy with virtually limitless and clean power.

The Triumph of SPARC's Magnet

The magnet, central to the SPARC fusion device being developed by MIT and Commonwealth Fusion Systems (CFS), met and exceeded all expectations during its test. This success marked the culmination of years of dedicated work. However, the work wasn’t done yet. In the following months, the team dismantled the magnet, analyzed data, and conducted additional tests to push the magnet to its limits. They aimed to understand potential failure modes and refine the design.

 

Dennis Whyte, the Hitachi America Professor of Engineering and former director of the PSFC, described this achievement as “the most important thing, in my opinion, in the last 30 years of fusion research.”

 

Before this breakthrough, the superconducting magnets required for fusion were too large and costly to be practical. The new magnet's compact size and reduced cost have transformed the economics of fusion reactors, decreasing the cost per watt by nearly 40 times. This dramatic improvement makes the construction of economically viable fusion power plants feasible.

The Superconducting Revolution

Fusion, the process that powers the sun, involves combining light atoms to release energy. Achieving this on Earth requires compressing fuel at extremely high temperatures and pressures, necessitating powerful magnetic fields produced by superconducting magnets. 

 

Traditional superconducting materials operate at 4 kelvins (-270 degrees Celsius), but the new magnet, a complete redesign, uses REBCO (rare-earth barium copper oxide), which functions at 20 kelvins. Despite being only 16 kelvins warmer, this difference significantly enhances material properties and engineering possibilities. 

The No-Insulation Innovation

One of the most daring innovations was the decision to eliminate traditional insulation around the superconducting tape. Conventional magnets use insulation to prevent short circuits, but the new design left the tape bare, relying on REBCO's superior conductivity. Initially met with skepticism, this approach proved effective, simplifying the fabrication process and improving performance.

The Road Ahead 

The achievement brings the dream of practical fusion power closer to reality. The innovative design and thorough testing have established a solid foundation for future fusion devices, positioning fusion as a viable solution for clean, limitless energy. As the SPARC project progresses, the insights gained from this achievement will continue to drive advancements in fusion technology, paving the way for a sustainable energy future.

 

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