Micro-Scale Fusion in Dense Relativistic Nanowire Array Plasmas

Abstract

Nuclear fusion is regularly created in spherical plasma compressions driven by multi-kilojoule pulses from the world's largest lasers. Here we demonstrate a dense microscale fusion environment created by irradiating arrays of deuterated nanostructures with joule-level pulses1 from a compact ultrafast frequency-doubled Ti:Sa laser developed at Colorado State University2, The irradiation of ordered deuterated polyethylene nanowires arrays with femtosecond pulses of relativistic intensity and ultra-high contrast (> 1 x 10 12) creates ultra-high energy density plasmas in which deuterons (D) are accelerated up to MeV energies, efficiently driving D-D fusion reactions and ultrafast neutron bursts. The ion specta were measured with a Thomson parabola, and the neutron yield with scintillator/photomultiplier neutron detectors calibrated with a dense plasma focus at the Nevada National Security Site. We measure up to 2 x 106 fusion neutrons per joule, an increase of about 500 times with respect to flat solid targets irradiated with the same laser pulses, a record yield for joule-level lasers. Moreover, in accordance with simulation predictions, we observe a rapid increase in neutron yield with laser pulse energy. The results will impact nuclear science and high energy density research and can lead to bright ultrafast quasi-monoenergetic neutron point sources for imaging and materials studies.