A femtosecond neutron source

The possibility of using the ultrashort ion bunches produced by circularly polarized laser pulses to drive a source of fusion neutrons with sub-optical cycle duration is discussed. A two-sided irradiation of a deuterated thin foil target produces two counter-moving ion bunches, whose collision produces an ultrashort neutron burst. Using particle-in-cell simulations and analytical modeling, it is calculated that, for intensities of a few 10¹⁹ W cm^-2, more than 10³ neutrons per Joule may be producedwithin a time shorter than one femtosecond. Another scheme based on a layered deuterium-tritium target is outlined. PACS 24.90.+d; 29.25.Dz; 52.38.ph; 52.50.Jm