Editing Tritium (section)

==== Neutron initiator ====
These are devices incorporated in [[nuclear weapon]]s which produce a pulse of neutrons when the bomb is detonated to initiate the [[fission reaction]] in the fissionable core (pit) of the bomb, after it is compressed to a [[critical mass]] by explosives.  Actuated by an ultrafast switch like a [[krytron]], a small [[particle accelerator]] drives [[ion]]s of tritium and deuterium to energies above the 15&nbsp;[[Electronvolt|keV]] or so needed for deuterium-tritium fusion and directs them into a metal target where the tritium and deuterium are [[Adsorption|adsorbed]] as [[hydride]]s. High-energy [[fusion neutron]]s from the resulting fusion radiate in all directions. Some of these strike plutonium or uranium nuclei in the primary's pit, initiating a [[nuclear chain reaction]]. The quantity of neutrons produced is large in absolute numbers, allowing the pit to quickly achieve neutron levels that would otherwise need many more generations of chain reaction, though still small compared to the total number of nuclei in the pit.