Neutron generation in deuterated nanowire arrays irradiated by femtosecond pulses of relativistic intensity*

Nuclear fusion is regularly created in spherical plasma compressions driven with multi-kilojoule lasers. Driving fusion reactions with compact lasers that can be fired at much higher repetition rates is also of interest. We have demonstrated a new dense fusion environment created by irradiating arrays of deuterated nanostructures with Joule--level pulses from a compact Ti:Sa laser. The irradiation of ordered deuterated polyethylene nanowires arrays with femtosecond pulses of relativistic intensity is shown to create ultra-high energy density plasmas in which deuterons are accelerated to MeV energies, efficiently driving D-D fusion reactions and ultrafast neutron pulses. We have measured up to 2 x 10$^{\mathrm{6}}$ fusion neutrons/Joule, a 500 times increase respect to flat solid targets, a record yield for Joule-level lasers, and have also observed a rapid increase in neutron yield with laser pulse energy. We present results of a first experiments conducted at intensities \textgreater 1 x 10$^{\mathrm{21}}$ W cm$^{\mathrm{-2}}$ that generated \textgreater 1 x 10$^{\mathrm{7}}$ fusion neutrons per shot.