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taylorvich [soylentnews.org] writes:

https://phys.org/news/2024-04-roots-lab-stellarator-years-door.html [phys.org]

For the first time, scientists have built a fusion experiment using permanent magnets, a technique that could show a simple way to build future devices for less cost and allow researchers to test new concepts for future fusion power plants.

Researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) combined decades of expertise in engineering, computation and theoretical physics to design a new type of stellarator, a twisty machine that confines plasma, the electrically charged fourth state of matter, to harness the fusion process that powers the sun and stars and potentially generate clean electricity.

"Using permanent magnets is a completely new way to design stellarators," said Tony Qian, a graduate student in the Princeton Program in Plasma Physics, which is based at PPPL. Qian was the lead author of papers published in the Journal of Plasma Physics and Nuclear Fusion that detail the theory and engineering behind the device, known as MUSE. "This technique allows us to test new plasma confinement ideas quickly and build new devices easily."

Stellarators typically rely on complicated electromagnets that have complex shapes and create their magnetic fields through the flow of electricity. Those electromagnets must be built precisely with very little room for error, increasing their cost.

However, permanent magnets, like the magnets that hold art to refrigerator doors, do not need electric currents to create their fields. They can also be ordered off the shelf from industrial suppliers and then embedded in a 3D-printed shell around the device's vacuum vessel, which holds the plasma.

"MUSE is largely constructed with commercially available parts," said Michael Zarnstorff, a senior research physicist at PPPL and principal investigator of the project. "By working with 3D-printing companies and magnet suppliers, we can shop around and buy the precision we need instead of making it ourselves."

The original insight that permanent magnets could be the foundation for a new, more affordable stellarator variety came to Zarnstorff in 2014. "I realized that even if they were situated alongside other magnets, rare-earth permanent magnets could generate and maintain the magnetic fields necessary to confine the plasma so fusion reactions can occur," Zarnstorff said, "and that's the property that makes this technique work."

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