Permanent magnets stronger than those on refrigerator could be a solution for delivering fusion energy

Rare earth magnets have surprising and useful properties. They generate quite powerful fields for the magnets' small size, and these are "hard" fields that are almost unaffected by other fields nearby.

Permanent magnets have disadvantages, too. "You can't turn them off," Helander said, which means they can pull in anything they can attract within range.