I understand that all efforts at present to make fusion work as an energy source have used light nuclei other than protons due to the fact that the cross section of the proton-proton reaction is just way too low, and it doesn't get much faster -- in fact, that the power density of stellar cores is really low, at under 1 kW per cubic meter.
But I also understand that the p-p reaction, or alternatively the CNO cycle or some other reactions where the fuel consists of protons may be able to be sped up under enough force. I also understand that when degenerate matter such as that in a white dwarf undergoing a type Ia supernova is compressed enough, it may fuse extremely quickly.
So the question is: Is there any reason to think that future technologies could ever make proton-fueled fusion happen at an appreciable rate without involving gravitational confinement? Is there any "ceiling" to the achievable reaction rates, or unpreventable losses that will prevent break-even, or fundamental reason why no sufficiently tight containment field can be generated?
(also, what if we had magical infinitely strong, rigid, and heat-resistant materials, could we do it then?)