23 Jun 2026
A company outside Boston just craned the second 48-ton half of a steel donut into Tokamak Hall and pushed its compact fusion reactor to 75% built, a machine ch…
For decades the recipe for a fusion reactor barely changed: build it enormous. A tokamak traps a cloud of gas hotter than the Sun inside a magnetic field, and for most of fusion’s history the only way to make that field strong enough was to make the machine huge. That is why ITER, the giant international reactor going up in southern France, is the size of a cathedral and has been under…
