Fusion Energy Projects are Not Trying to Imitate the Sun

The quest to use fusion power for break-even electricity generation has sometimes been described as “putting the sun in a jar”. Where by “jar,” we mean a carefully arranged series of coils that produce a powerful confining magnetic field. Usually it’s called a tokamak (toroidal design) or stellarator (complicated twisty design that is still topologically a toroid). The sun is so enormous that confinement happens as a natural result of its own gravitational field. On the other hand, the relatively small amount of plasma in a fusion reactor on Earth needs to be squeezed from the outside. But other than the nature of the confining force, you might think that the fusion reactions in a reactor are basically the same, physics-wise, as the fusion reactions in the sun. This is not true.

The quest to use fusion power for break-even electricity generation has sometimes been described as “putting the sun in a jar”. Where by “jar,” we mean a carefully arranged series of coils that produce a powerful confining magnetic field. Usually it’s called a tokamak (toroidal design) or stellarator (complicated twisty design that is still topologically a toroid).

The sun is so enormous that confinement happens as a natural result of its own gravitational field. On the other hand, the relatively small amount of plasma in a fusion reactor on Earth needs to be squeezed from the outside. But other than the nature of the confining force, you might think that the fusion reactions in a reactor are basically the same, physics-wise, as the fusion reactions in the sun.

This is not true.

https://notoneunusualthing.substack.com/p/fusion-energy-projects-are-not-trying