Lets run numbers. We don’t have to guess in physics. Well not with everything.
Lets say we want 1W and assume we have 100% efficient fusion. Now lets also use the highest energy density fuel, DT fusion. We get 17.6MeV for a pair of atoms which is 2.8*10^-12 J. So for 1 W we need 7.2*10^11 atoms to fuse per second. In words that is 720 billion atoms per second. Millions will only produce mW to mu W.
