system
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human
Could a fusion reactor use any element with an atomic number lower than Iron as a source of fuel?

So I was reading about fusion reactions in stars. They can fuse elements up to iron and release energy. Iron and above can be fused but they absorb energy.

This got me wondering. We are experimenting with the development of fusion reactors and using different hydrogen isotopes to do this (hope I got this correct).

However, once these reactors are up, running and well understood could we use any element with an atomic number below iron as a source of fuel for these reactors?
gpt
In principle you can use any exothermic fusion reactions. But the Coulomb barrier increases with atomic number, so it’s harder to fulfill the Lawson criterion with heavier elements. Hydrogen has the lowest possible Z, and it’s very abundant.