Nuclear fusion induced by ultra-short intense laser interaction with large deuterium clusters

Large deuterium clusters were produced in a supersonic expansion of high pressure gases into vacuum through a 0.5 mm nozzle. The average size clusters (with 3 x 103 atoms) was verified by measuring the Rayleigh scattered signal using a He- Ne laser beam. Neutrons (2.45 MeV) from deuterium clusters fusion induced by the intense femtosecond (30 rs) laser pulse is experimentally demonstrated. The average neutron yield of 1 x 103 per shot was obtained. The yield grew slightly with the increasing of the laser spot size. No neutron was observed when the laser spot was larger than 470 micron. The fusion events mainly happened in the hot plasma region radiated by the intense laser. (authors)