[Hah et al. "High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D₂O." Applied Physics Letters (2016)]

The study demonstrates a compact way to make neutrons using very short (35 femtoseconds), modest-energy laser pulses (a few millijoules) focused on a stream of heavy water (D₂O). The laser interaction accelerates deuterons (nuclei of heavy hydrogen) which then collide with other deuterons to produce fast neutrons via fusion reactions. Because the heavy water flow is continuous, this scheme allows many pulses per second (high repetition rate), giving a steady neutron output rather than just occasional bursts. Although each pulse produces relatively few neutrons compared to large laser facilities, the approach shows promise for neutron sources that are smaller, more practical, and usable for applications - such as materials testing or medical imaging - where steady, frequent operation outweighs sheer peak output.