I've heard that Sun is not hot enough to sustain thermonuclear fusion at the level we observe. Instead, the solar output relies on quantum tunneling of protons through their natural repulsive barrier. Might this same effect be useful in obtaining controlled thermonuclear fusion? It seems to me that this would require a large quantity of atomic interactions in a confined space. Might an atom laser be useful in producing a finely tuned beam of atoms that could direct large numbers of atoms into a small enough space for them to fuse?