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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.

Results of a study of laser induced damage of ion beam sputtered single layers and capped single layers of Sc2O3, HfO2 and Ta2O5 in a controlled atmosphere and in an ultra-high vacuum (UHV) show the choice of material is paramount to achieving the best performance.

We discuss the results of work directed toward the development of high energy (>;1 J), high average power, diode-pumped picosecond lasers. The design and operation of diode-pumped chirped-pulse-amplification Yb:YAG lasers that combine either room temperature or cryogenically-cooled regenerative amplifiers with cryo-cooled power amplifiers for superior thermal performance and efficient energy extraction are discussed. Results obtained using thick-disk amplifiers include the generation of 100 mJ, 5-ps duration laser pulses at 100-Hz repetition rate, and 1-J pulses of 8.5-ps duration at 10-Hz repetition rate. The performance of the amplifiers in terms of pulse energy and bandwidth under a variety of pump condition is presented.

The efficient conversion of optical laser light into bright ultrafast x-ray pulses in laser created plasmas is of high interest for dense plasma physics studies, material science, and other fields. However, the rapid hydrodynamic expansion that cools hot plasmas has limited the x-ray conversion efficiency (CE) to 1% or less. Here we demonstrate more than one order of magnitude increase in picosecond x-ray CE by tailoring near solid density plasmas to achieve a large radiative to hydrodynamic energy loss rate ratio, leading into a radiation loss dominated plasma regime. A record 20% CE into ℎ>1 keVhν>1 keV photons was measured in arrays of large aspect ratio Au nanowires heated to keV temperatures with ultrahigh contrast femtosecond laser pulses of relativistic intensity. The potential of these bright ultrafast x-ray point sources for table-top imaging is illustrated with single shot flash radiographs obtained using low laser pulse energy. These results will enable the deployment of brighter laser driven x-ray sources at both compact and large laser facilities. Fil: Hollinger, Reed. Department Of Electrical And Engineering; Fil: Bargsten, Clayton. Department Of Electrical And Engineering; Fil: Shlyaptsev, Vyacheslav N.. Department Of Electrical And Engineering; Fil: Kaymak, Vural. Institut Fur Theoretische Physik, Heinrich-heine-univer; Fil: Pukhov, Alexander. Heinrich-heine-universität Düsseldorf; 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. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Wang, Shoujun. Department Of Electrical And Engineering; Fil: Rockwood, Alex. Department Of Electrical And Engineering; Fil: Wang, Yong. Department Of Electrical And Engineering; Fil: Townsend, Amanda. Department Of Electrical And Engineering; Fil: Prieto, Amy. Department Of Electrical And Engineering; Fil: Stockton, Patrick. Department Of Electrical And Engineering; Fil: Curtis, Alden. Department Of Electrical And Engineering; Fil: Rocca, Jorge J.. Department Of Electrical And Engineering

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.

We have investigated scintillator efficiency for MeV radiographic imaging. This paper discusses the modeled detection efficiency and measured brightness of a number of scintillator materials. An optical imaging camera records images of scintillator emission excited by a pulsed x-ray machine. The efficiency of various thicknesses of monolithic LYSO:Ce (cerium-doped lutetium yttrium orthosilicate) are being studied to understand brightness and resolution trade-offs compared with a range of micro-columnar CsI:Tl (thallium-doped cesium iodide) scintillator screens. The micro-columnar scintillator structure apparently provides an optical gain mechanism that results in brighter signals from thinner samples. The trade-offs for brightness versus resolution in monolithic scintillators is straightforward. For higher-energy x-rays, thicker materials generally produce brighter signal due to x-ray absorption and the optical emission properties of the material. However, as scintillator thickness is increased, detector blur begins to dominate imaging system resolution due to the volume image generated in the scintillator thickness and the depth of field of the imaging system. We employ a telecentric optical relay lens to image the scintillator onto a recording CCD camera. The telecentric lens helps provide sharp focus through thicker-volume emitting scintillators. Stray light from scintillator emission can also affect the image scene contrast. We have applied an optical light scatter model to the imaging system to minimize scatter sources and maximize scene contrasts.

Ultrafast scintillators are the subject of current research in an effort to better resolve ultrafast phenomena in high-energy density physics (HEDP) experiments. Despite extensive research on new scintillator materials, the essential mechanism of energy absorption, excitation, and photo-emission has remained unchanged for over 50 years. Recently, a new class of semiconductor detector has been developed utilizing the radoptic effect, or the change of refractive index when subjected to radiation, in an attempt to record events faster than conventional scintillators.1 This study was designed for the observation of the radoptic effect by optical interferometry in different semiconductors to experimentally determine the fastest and most sensitive materials for the optimization of current radsensors.

A diode-pumped cryogenic Yb:YAG CPA laser that produces 1J, 5ps pulses allowed for the first time the uninterrupted generation of 1.8x10^5 sub-20nm wavelength laser pulses with microjoule energy at 100Hz repetition rate on a table-top.

The table-top generation of high average power coherent soft x-ray radiation in a compact set up is of high interest for numerous applications. We have demonstrated the generation of bright soft x-ray laser pulses at 100 Hz repetition rate with record-high average power from compact plasma amplifiers excited by an ultrafast diode-pumped solid state laser. Results of compact λ=18.9nm Ni-like Mo and λ=13.9nm Ni-like Ag lasers operating at 100 Hz repetition rate are discussed.

Cygnus is a high-energy radiographic x-ray source. Three large zoom lenses have been assembled to collect images from large scintillators. A large elliptical pellicle (394 × 280 mm) deflects the scintillator light out of the x-ray path into an eleven-element zoom lens coupled to a CCD camera. The zoom lens and CCD must be as close as possible to the scintillator to maximize light collection. A telecentric lens design minimizes image blur from a volume source. To maximize the resolution of objects of different sizes, the scintillator and zoom lens are translated along the x-ray axis, and the zoom lens magnification changes. Zoom magnification is also changed when different-sized recording cameras are used (50 or 62 mm square format). The LYSO scintillator measures 200 × 200 mm and is 5 mm thick. The scintillator produces blue light peaking at 435 nm, so special lens materials are required. By swapping out one doublet and allowing all other lenses to be repositioned, the zoom lens can also use a CsI(Tl) scintillator that produces green light centered at 540 nm (for future operations). All lenses have an anti-reflective coating for both wavelength bands. Two sets of doublets, the stop, the scintillator, and the CCD camera move during zoom operations. One doublet has x-y compensation. Alignment of the optical elements was accomplished using counter propagating laser beams and monitoring the retro-reflections and steering collections of laser spots. Each zoom lens uses 60 lb of glass inside the 425 lb mechanical structure, and can be used in either vertical or horizontal orientation.

Compact λ = 13.9 nm and λ = 18.9 nm lasers with record >0.1 mW average power were demonstrated using a 100 Hz repetition rate diode-pumped CPA laser. Successful scaling to λ = 10.9 nm is reported.

Our goal is to collect x-ray images of different sized targets, which are positioned inside a containment vessel, onto different sized CCD cameras.

We demonstrate the operation of a gain-saturated table-top soft x-ray laser at 100 Hz repetition rate. The laser generates an average power of 0.15 mW at λ=18.9 nm, the highest laser power reported to date from a sub-20-nm wavelength compact source. Picosecond laser pulses of 1.5 μJ energy were produced at λ=18.9 nm by amplification in a Mo plasma created by tailoring the temporal intensity profile of single pump pulses with 1 J energy produced by a diode-pumped chirped pulse amplification Yb:YAG laser. Lasing was also obtained in the 13.9 nm line of Ni-like Ag. These results increase by an order of magnitude the repetition rate of plasma-based soft x-ray lasers opening the path to milliwatt average power table-top lasers at sub-20 nm wavelengths.

We have demonstrated the generation of bright soft x-ray laser pulses with record-high average power from compact plasma amplifiers excited by ultrafast solid state lasers. These lasers have numerous applications in nanoscience and nanotechnology.

We report the highest repetition rate table-top soft x-ray laser, 50Hz. Microjoule-level picosecond laser pulses were produced at λ=18.9nm by amplification in a molybdenum plasma generated by a 1 J diode-pumped chirped-pulse-amplification Yb-YAG laser.

We discuss recent advances in the development of high repetition rate table-soft soft x-ray lasers resulting from research conducted at Colorado State University. Advancing saturated table-top lasers to shorter wavelengths we report the operation of gain-saturated sub-10 nm table-top lasers at 1 Hz repetition rate. We also present experimental results that show that injection-seeding of solid-target soft x-ray plasma amplifiers reduces the far field divergence by an order of magnitude and to allow for control of the far-field beam characteristics by tailoring the divergence of the seed. We finally discuss progress towards the development of high repetition rate compact all-diode-pumped soft x-ray lasers. We have operated the front end of the diode-pumped soft-ray laser driver at 100Hz repetition rate, obtaining sub-5 ps optical laser pulses of 100 mJ energy.

Small variations of oxygen partial pressure during the ion beam sputtering of metal oxides strongly influence the optical properties, causing an increase in the absorption loss and a decrease in laser damage fluence.

We report the first demonstration of an all-diode-pumped soft xray laser system. Lasing was achieved in the λ?= 18.9 nm line of Ni-like Mo ions pumping with a diode-pumped cryo-cooled Yb:YAG chirped-pulse-amplification laser system that generates 1 J pulses of 8.5 ps duration. Driver lasers pump by diodes opens the possibility to develop a new generation more compact soft x-ray lasers operating at significantly increased repetition rates for applications.

We review recent progress in the development of table-top soft x-ray lasers that includes the demonstration of a gain-saturated λ= 10.9 nm laser, and the first demonstration of an all-diode-pumped soft x-ray laser.

We report the demonstration of an 18.9nm soft x-ray laser pumped by a compact; all diode pumped chirped pulse amplification laser system producing 1J, 8.5ps pulses at 10Hz repetition rate.

The first soft x-ray laser pumped by laser diodes is reported. Lasing was achieved on the 18.9 nm line of nickel-like molybdenum pumping with a Yb:YAG chirped pulse amplification system with 1 J energy.

We have demonstrated a compact diode-pumped chirped pulse amplification laser based on cryogenically-cooled Yb:YAG that produces 1 J, 8.5 ps duration pulses at 10 Hz repetition rate.

We review recent advances in the development of high repetition rate table-top soft X-ray lasers that includes their extension to wavelengths down to 10.9 nm and the first demonstration of an all-diode-pumped soft x-ray laser.

We have demonstrated an all-diode-pumped Yb:YAG chirped pulse amplification laser that produces 100 mJ pulses of 5 ps duration at 100 Hz repetition rate. The compact laser system combines a room-temperature Yb:YAG regenerative amplifier for increased bandwidth and a cryogenically cooled Yb:YAG four-pass amplifier for improved heat dissipation and increased efficiency. The optical efficiency of this amplifier is higher than that of other diode-pumped systems of comparable energy.

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.