One way of generating neutrons is by fusing D-D or D with T. In neutron generators that work by acceleration D-ions into a solid matrix of e.g. metal and T or D (metal hydrides). Such generators can produce up to 10^8 neutrons per second. I'm wondering, could they be tweaked to even higher levels to eventually produce a net amount of energy? The best result for the polywell was for example 10^9 fusions/sec, not far off from 10^8 fusions/sec.
Neutron generators use a solid target, metal lattice filled with D2 or tritium, metal hydrides. The fusion reactions
D + T → n + 4He En = 14.1 MeV
D + D → n + 3He En = 2.5 MeV
happen within the lattice, most of the neutrons escape since they do not interact electromagnetically and generate the neutron source. There is no way a self sustaining reaction could exist within the lattice using the above energies so that the balance of (output energy -input energy ) could become positive and thus be an energy source.Interestingly there exist simpler neutron generators, patented and sold .In their own words: