Controlled fusion on Earth

William Happer

September 18, 2024

The Sun’s fusion power is mostly from the fusion of two protons P to form deuterium D, P+P->D + positron + neutrino. This is a very slow “weak” interaction that has nothing to do with what is called fusion power on Earth. All Earthly fusion schemes, starting with the easiest, D+T -> He4+N, reshuffle the arrangements of protons and neutrons in nuclei, where they are bound by the “strong” nuclear force. In earthly fusion, no neutrinos are involved, and there is no conversion of protons to neutrons or vice versa. The closest thing to the Sun’s fusion on Earth, is beta radioactivity, that does produce neutrinos, but this is of no practical significance for producing large amounts of power. And tritium T for earthly fusion has to be manufactured. There are no tritium mines, and tritium beta decays to He3 with a half-life of about 12 years.

There is no way to reproduce the fusion reactions of the Sun or stars on Earth since there is no way to confine hot protons long enough to let them fuse with the aid of weak interactions. Even in the incredibly hot, dense, and vast core of the Sun, the fusion power generated per unit volume is about 1/10 of that released by metabolism in our own bodies, and about the same as a good compost pile. References to fusion power of the Sun is more irrelevant hype.