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?