# Has proton-proton fusion ever been seriously considered for an artificial fusion reactor?

All contemporary efforts to perform nuclear fusion as a source of power have focused on reactions between isotopes (often deuterium, tritium, or He3) and/or light elements (often boron or lithium isotopes). These have vastly larger cross sections / rates of reaction than the p-p or CNO-catalysis reactions that power main-sequence stars, that have power densities of only a few hundred watts per cubic meter.

One sees so little discussion of the possibility of artificial p-p fusion reactors that it's sometimes hard to even find detailed explanation of why nobody tries.

What I would like to ask is: has there ever been serious consideration of the potential for such a device? For example, were they envisioned in the early days of fusion research or by some of the more speculative Bussard projects?

• It's not exactly a duplicate, but this is addressed by the answers to How much faster is the fusion we make on earth compared to the fusion that happens in the sun?. Specifically note the comment in my answer: The p-p fusion is about $10^{26}$ times slower than the D-T fusion. – John Rennie Jun 26 '19 at 5:49
• It is definitely worthwhile background information, but that doesn't cover artificial equipment at all, which seems relevant given that our research reactors exceed the sun in some parameters. – ikrase Jun 26 '19 at 5:52
• The p-p fusion has $10^{26}$ times smaller cross section than the d-t fusion. That's why it has never been seriously considered for a artificial reactor. Any such reactor would yield a ridiculously small amount of energy. – John Rennie Jun 26 '19 at 5:58
• @ikrase how can you go around a crossection? the sun does it with a lot of protons and a lot of energy in the plasma space.com/26956-proton-fusion-sun-power-source-infographic.html – anna v Jun 26 '19 at 8:07
• I would take the position that noting the difference in cross-sections is exactly what "serious consideration" means. That is how you winnow design possibilities and decide where to spend you effort. Some options are so obviously hard that they are not worth your precious time. If you think it should mean something else perhaps you could elaborate on exactly what that is. Are you asking if anyone has ever poured years of effort and hundreds of pages into that rat hole? – dmckee --- ex-moderator kitten Jun 26 '19 at 13:42