The second one is the reactor neutron source, which, as the name implies, uses nuclear fission reactors to generate a large number of neutrons.
However, if he were to manage to create a nuclear reactor now, there wouldn't be the need to worry about how to "ignite" a nuclear explosion!
So, this method could only be ruled out!
The third one is the accelerator neutron source, which utilizes various charged particle accelerators to accelerate particles such as protons or deuterium, and then bombards a target nucleus to generate neutrons. Its advantage lies in the intensity of the neutrons obtained are much greater than those from radioactive isotope neutron sources, and it can obtain monoenergetic neutrons across a wide energy range.
Simply put, the principle behind these methods is the same—that is, particles or rays strike an element serving as the target, knocking out neutrons from within!
