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We report a significant enhancement in both the energy and the flux of relativistic electrons accelerated by ultra-intense laser pulse irradiation (>1 10 21 W cm-2) of near solid density aligned CD2 nanowire arrays in comparison to those from solid CD2 foils irradiated with the same laser pulses. Ultrahigh contrast femtosecond laser pulses penetrate deep into the nanowire array creating a large interaction volume. Detailed three dimensional relativistic particle-in-cell simulations show that electrons originating anywhere along the nanowire length are first driven towards the laser to reach a lower density plasma region near the tip of the nanowires, where they are accelerated to the highest energies. Electrons that reach the lower density plasma experience direct laser acceleration up to the dephasing length, where they outrun the laser pulse. This yields an electron beam characterized by a 3 higher electron temperature and an integrated flux 22.4 larger respect to foil targets. Additionally, the generation of >1 MeV photons were observed to increase up to 4.5. Fil: Moreau, A.. State University of Colorado - Fort Collins; Estados Unidos Fil: Hollinger, R.. State University of Colorado - Fort Collins; Estados Unidos Fil: Calvi, C.. State University of Colorado - Fort Collins; Estados Unidos Fil: Wang, S.. State University of Colorado - Fort Collins; Estados Unidos Fil: Wang, Y.. State University of Colorado - Fort Collins; Estados Unidos Fil: Capeluto, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Rockwood, A.. State University of Colorado - Fort Collins; Estados Unidos Fil: Curtis, A.. State University of Colorado - Fort Collins; Estados Unidos Fil: Kasdorf, S.. State University of Colorado - Fort Collins; Estados Unidos Fil: Shlyaptsev, V.N.. State University of Colorado - Fort Collins; Estados Unidos Fil: Kaymak, V.. Universitat Dusseldorf; Alemania Fil: Pukhov, A.. Universitat Dusseldorf; Alemania Fil: Rocca, J.J.. State University of Colorado - Fort Collins; Estados Unidos

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 fusion environment created by irradiating arrays of deuterated nanostructures with joule-level pulses from a compact ultrafast laser. The irradiation of ordered deuterated polyethylene nanowires arrays with femtosecond pulses of relativistic intensity 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. We measure up to 2 × 106 fusion neutrons per joule, an increase of about 500 times with respect to flat solid targets, 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., Neutron beams are useful studying fundamental physics problems, fusion process and material properties. Here the authors use intense laser irradiation of deuterated nanowire array targets to create high energy density plasmas capable of efficient generation of ultrafast neutron pulses.

We demonstrate the generation of 0.85 PW, 30 fs pulses at a repetition rate of 3.3 Hz from a Ti:Sapphire laser system. Ultra-high contrast second harmonic fs pulses at 400 nm were generated with >40% efficiency and focused to an intensity of 6.5×1021 W/cm2.

The irradiation of high aspect ratio, vertically aligned nanoscale rods with ultrahigh contrast $(> 10^{12})$ , femtosecond laser pulses at highly relativistic intensities $(> 10^{21}\text{Wcm}^{-2})$ provides a unique combination of drastically enhanced light penetration deep into the near solid density target. This results in the material being volumetrically heated to depths two orders of magnitude greater than the skin depth of the material, creating a large volume, ultrahigh energy density $(> 10^{9}\text{Jcm}^{-3})$ plasma1. Time integrated spectroscopic measurements of Au and Ni nanowire plasmas at an intensity of $5\mathrm{x}10^{18}\text{Wcm}^{-2}(\mathrm{a}_{\mathrm{o}}=1)$ demonstrated the creation of multi- keV, near solid density plasmas ionized to the Au $52+$ and $\text{Ni}^{26+}$ charge states2. The radiative lifetime of these plasmas is significantly decreased due to their high electron density while their hydrodynamic expansion time is greatly increased due to their large size. The result is a large increase in the conversion of the optical laser light into hv > 1keV x-rays. Previously, the conversion efficiency has been shown to exceed 20% into 4 pi steradians when irradiating 80nm diameter, 12% of solid density, Au nanowires at an intensity of $4\mathrm{x}10^{19}\text{Wcm}^{-2\ 3}$ . Here we present the first results of Au nanowires irradiated at highly relativistic intensity of $5\mathrm{x}10^{21}\text{Wcm}^{-2}$ corresponding to $\mathrm{a}_{\mathrm{o}}=17$ . Results of experiments conducted with a variety of nanowire diameters and at various fractions of solid density will be presented and compared to the results of particle in cell simulations.

We demonstrated 0.85PW, 30fs pulses at a repetition rate of 3.3Hz from a Ti:Sapphire laser. Ultra-high contrast λ=400 nm fs pulses were generated with > 40% efficiency and focused to an intensity of 6.5×1021W/cm2.

We demonstrate the generation of 0.85 PW, 30 fs laser pulses at a repetition rate of 3.3 Hz with a record average power of 85 W from a Ti:sapphire laser. The system is pumped by high-energy Nd:glass slab amplifiers frequency doubled in LiB3O5 (LBO). Ultrahigh-contrast λ=400 nm femtosecond pulses were generated in KH2PO4 (KDP) with >40% efficiency. An intensity of 6.5×1021 W/cm2 was obtained by frequency doubling 80% of the available Ti:sapphire energy and focusing the doubled light with an f/2 parabola. This laser will enable highly relativistic plasma experiments to be conducted at high repetition rate.

Irradiation of deuterated nanowire arrays with femtosecond pulses of relativistic intensity creates ultra-high energy density plasmas where deuterons are accelerated to MeV energies, efficiently driving D-D fusion reactions with record neutron yield for joule-level lasers.