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Sample records for laser compression experiments

  1. Fast optics for the Rutherford laser compression experiments

    International Nuclear Information System (INIS)

    Micholas, D.J.

    1976-12-01

    The compression chamber optical system proposed for the Rutherford Laboratory Laser compression experiments is described. The system corrects for longitudinal spherical aberration giving a final spot size approximately 15 μm. This could theoretically be improved. The two laser beams are focused via a pair of F/1.2 aspheric lenses onto a double-pass 'clam shell' aspheric mirror system. An analysis of the lens and mirror system is given and compared with an alternative ellipsoidal system already developed. The problems of manufacturing aspheric lenses to operate at 1.06 μm are outlined and an alternative novel approach to this design given. (author)

  2. Configuring and Characterizing X-Rays for Laser-Driven Compression Experiments at the Dynamic Compression Sector

    Science.gov (United States)

    Li, Y.; Capatina, D.; D'Amico, K.; Eng, P.; Hawreliak, J.; Graber, T.; Rickerson, D.; Klug, J.; Rigg, P. A.; Gupta, Y. M.

    2017-06-01

    Coupling laser-driven compression experiments to the x-ray beam at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS) of Argonne National Laboratory requires state-of-the-art x-ray focusing, pulse isolation, and diagnostics capabilities. The 100J UV pulsed laser system can be fired once every 20 minutes so precise alignment and focusing of the x-rays on each new sample must be fast and reproducible. Multiple Kirkpatrick-Baez (KB) mirrors are used to achieve a focal spot size as small as 50 μm at the target, while the strategic placement of scintillating screens, cameras, and detectors allows for fast diagnosis of the beam shape, intensity, and alignment of the sample to the x-ray beam. In addition, a series of x-ray choppers and shutters are used to ensure that the sample is exposed to only a single x-ray pulse ( 80ps) during the dynamic compression event and require highly precise synchronization. Details of the technical requirements, layout, and performance of these instruments will be presented. Work supported by DOE/NNSA.

  3. Compressive laser ranging.

    Science.gov (United States)

    Babbitt, Wm Randall; Barber, Zeb W; Renner, Christoffer

    2011-12-15

    Compressive sampling has been previously proposed as a technique for sampling radar returns and determining sparse range profiles with a reduced number of measurements compared to conventional techniques. By employing modulation on both transmission and reception, compressive sensing in ranging is extended to the direct measurement of range profiles without intermediate measurement of the return waveform. This compressive ranging approach enables the use of pseudorandom binary transmit waveforms and return modulation, along with low-bandwidth optical detectors to yield high-resolution ranging information. A proof-of-concept experiment is presented. With currently available compact, off-the-shelf electronics and photonics, such as high data rate binary pattern generators and high-bandwidth digital optical modulators, compressive laser ranging can readily achieve subcentimeter resolution in a compact, lightweight package.

  4. Flash Kα radiography of laser-driven solid sphere compression for fast ignition

    International Nuclear Information System (INIS)

    Sawada, H.; Lee, S.; Nagatomo, H.; Arikawa, Y.; Nishimura, H.; Ueda, T.; Shigemori, K.; Fujioka, S.; Shiroto, T.; Ohnishi, N.; Sunahara, A.; Beg, F. N.; Theobald, W.; Pérez, F.; Patel, P. K.

    2016-01-01

    Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while a flash of 4.51 keV Ti Kα x-ray backlighter was produced by a high-intensity, picosecond laser LFEX (Laser for Fast ignition EXperiment) near peak compression for radiography. Areal densities of the compressed core were inferred from two-dimensional backlit x-ray images recorded with a narrow-band spherical crystal imager. The maximum areal density in the experiment was estimated to be 87 ± 26 mg/cm"2. The temporal evolution of the experimental and simulated areal densities with a 2-D radiation-hydrodynamics code is in good agreement.

  5. Flash Kα radiography of laser-driven solid sphere compression for fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, H. [Department of Physics, University of Nevada Reno, Reno, Nevada 89557 (United States); Lee, S.; Nagatomo, H.; Arikawa, Y.; Nishimura, H.; Ueda, T.; Shigemori, K.; Fujioka, S. [Institute of Laser Engineering, Osaka University, Suita, Osaka (Japan); Shiroto, T.; Ohnishi, N. [Department of Aerospace Engineering, Tohoku University, Sendai, Miyagi (Japan); Sunahara, A. [Institute of Laser Technology, Nishi-ku, Osaka (Japan); Beg, F. N. [University of California San Diego, La Jolla, California 92093 (United States); Theobald, W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Pérez, F. [LULI, Ecole Polytechnique, Palaiseau, Cedex (France); Patel, P. K. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2016-06-20

    Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while a flash of 4.51 keV Ti Kα x-ray backlighter was produced by a high-intensity, picosecond laser LFEX (Laser for Fast ignition EXperiment) near peak compression for radiography. Areal densities of the compressed core were inferred from two-dimensional backlit x-ray images recorded with a narrow-band spherical crystal imager. The maximum areal density in the experiment was estimated to be 87 ± 26 mg/cm{sup 2}. The temporal evolution of the experimental and simulated areal densities with a 2-D radiation-hydrodynamics code is in good agreement.

  6. Limiting effects on laser compression by resonant backward Raman scattering in modern experiments

    International Nuclear Information System (INIS)

    Yampolsky, Nikolai A.; Fisch, Nathaniel J.

    2011-01-01

    Through resonant backward Raman scattering, the plasma wave mediates the energy transfer between long pump and short seed laser pulses. These mediations can result in pulse compression at extraordinarily high powers. However, both the overall efficiency of the energy transfer and the duration of the amplified pulse depend upon the persistence of the plasma wave excitation. At least with respect to the recent state-of-the-art experiments, it is possible to deduce that at present the experimentally realized efficiency of the amplifier is likely constrained mainly by two effects, namely, the pump chirp and the plasma wave wavebreaking.

  7. Intra-pulse laser absorption sensor with cavity enhancement for oxidation experiments in a rapid compression machine

    KAUST Repository

    Nasir, Ehson Fawad

    2018-05-23

    A sensor based on a mid-IR pulsed quantum cascade laser (QCL) and off-axis cavity enhanced absorption spectroscopy (OA-CEAS) has been developed for highly sensitive concentration measurements of carbon monoxide (CO) in a rapid compression machine. The duty cycle and the pulse repetition rate of the laser were optimized for increased tuning range, high chirp rate, and small line width to achieve effective laser-cavity coupling. This enabled spectrally resolved CO line-shape measurements at high pressures (P ~10 bar). A gain factor of 133 and a time resolution of 10 μs were demonstrated. CO concentration-time profiles during the oxidation of highly dilute n-octane/air mixtures were recorded, illustrating new opportunities in RCM experiments for chemical kinetics.

  8. Laser driven single shock compression of fluid deuterium from 45 to 220 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, D; Boehly, T; Celliers, P; Eggert, J; Moon, S; Meyerhofer, D; Collins, G

    2008-03-23

    The compression {eta} of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance match model derived from a best fit to absolute Hugoniot data has been used to quantify and minimize the systematic errors caused by uncertainties in the high-pressure Al equation of state. In deuterium below 100 GPa results show that {eta} {approx_equal} 4.2, in agreement with previous impedance match data from magnetically-driven flyer and convergent-explosive shock wave experiments; between 100 and 220 GPa {eta} reaches a maximum of {approx}5.0, less than the 6-fold compression observed on the earliest laser-shock experiments but greater than expected from simple extrapolations of lower pressure data. Previous laser-driven double-shock results are found to be in good agreement with these single-shock measurements over the entire range under study. Both sets of laser-shock data indicate that deuterium undergoes an abrupt increase in compression at around 110 GPa.

  9. Neutralized drift compression experiments with a high-intensity ion beam

    International Nuclear Information System (INIS)

    Roy, P.K.; Yu, S.S.; Waldron, W.L.; Anders, A.; Baca, D.; Barnard, J.J.; Bieniosek, F.M.; Coleman, J.; Davidson, R.C.; Efthimion, P.C.; Eylon, S.; Friedman, A.; Gilson, E.P.; Greenway, W.G.; Henestroza, E.; Kaganovich, I.; Leitner, M.; Logan, B.G.; Sefkow, A.B.; Seidl, P.A.; Sharp, W.M.; Thoma, C.; Welch, D.R.

    2007-01-01

    To create high-energy density matter and fusion conditions, high-power drivers, such as lasers, ion beams, and X-ray drivers, may be employed to heat targets with short pulses compared to hydro-motion. Both high-energy density physics and ion-driven inertial fusion require the simultaneous transverse and longitudinal compression of an ion beam to achieve high intensities. We have previously studied the effects of plasma neutralization for transverse beam compression. The scaled experiment, the Neutralized Transport Experiment (NTX), demonstrated that an initially un-neutralized beam can be compressed transversely to ∼1 mm radius when charge neutralization by background plasma electrons is provided. Here, we report longitudinal compression of a velocity-tailored, intense, neutralized 25 mA K + beam at 300 keV. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhances the beam peak current by a factor of 50 and produces a pulse duration of about 3 ns. The physics of longitudinal compression, experimental procedure, and the results of the compression experiments are presented

  10. Laser driven supersonic flow over a compressible foam surface on the Nike laser

    International Nuclear Information System (INIS)

    Harding, E. C.; Drake, R. P.; Gillespie, R. S.; Visco, A.; Grosskopf, M. J.; Ditmar, J. R.; Aglitskiy, Y.; Velikovich, A. L.; Weaver, J. L.; Plewa, T.

    2010-01-01

    A laser driven millimeter-scale target was used to generate a supersonic shear layer in an attempt to create a Kelvin-Helmholtz (KH) unstable interface in a high-energy-density (HED) plasma. The KH instability is a fundamental fluid instability that remains unexplored in HED plasmas, which are relevant to the inertial confinement fusion and astrophysical environments. In the experiment presented here the Nike laser [S. P. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to create and drive Al plasma over a rippled foam surface. In response to the supersonic Al flow (Mach=2.6±1.1) shocks should form in the Al flow near the perturbations. The experimental data were used to infer the existence and location of these shocks. In addition, the interface perturbations show growth that has possible contributions from both KH and Richtmyer-Meshkov instabilities. Since compressible shear layers exhibit smaller growth, it is important to use the KH growth rate derived from the compressible dispersion relation.

  11. Laser-pulse compression in a collisional plasma under weak-relativistic ponderomotive nonlinearity

    International Nuclear Information System (INIS)

    Singh, Mamta; Gupta, D. N.

    2016-01-01

    We present theory and numerical analysis which demonstrate laser-pulse compression in a collisional plasma under the weak-relativistic ponderomotive nonlinearity. Plasma equilibrium density is modified due to the ohmic heating of electrons, the collisions, and the weak relativistic-ponderomotive force during the interaction of a laser pulse with plasmas. First, within one-dimensional analysis, the longitudinal self-compression mechanism is discussed. Three-dimensional analysis (spatiotemporal) of laser pulse propagation is also investigated by coupling the self-compression with the self-focusing. In the regime in which the laser becomes self-focused due to the weak relativistic-ponderomotive nonlinearity, we provide results for enhanced pulse compression. The results show that the matched interplay between self-focusing and self-compression can improve significantly the temporal profile of the compressed pulse. Enhanced pulse compression can be achieved by optimizing and selecting the parameters such as collision frequency, ion-temperature, and laser intensity.

  12. Laser-pulse compression in a collisional plasma under weak-relativistic ponderomotive nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mamta; Gupta, D. N., E-mail: dngupta@physics.du.ac.in [Department of Physics and Astrophysics, North Campus, University of Delhi, Delhi 110 007 (India)

    2016-05-15

    We present theory and numerical analysis which demonstrate laser-pulse compression in a collisional plasma under the weak-relativistic ponderomotive nonlinearity. Plasma equilibrium density is modified due to the ohmic heating of electrons, the collisions, and the weak relativistic-ponderomotive force during the interaction of a laser pulse with plasmas. First, within one-dimensional analysis, the longitudinal self-compression mechanism is discussed. Three-dimensional analysis (spatiotemporal) of laser pulse propagation is also investigated by coupling the self-compression with the self-focusing. In the regime in which the laser becomes self-focused due to the weak relativistic-ponderomotive nonlinearity, we provide results for enhanced pulse compression. The results show that the matched interplay between self-focusing and self-compression can improve significantly the temporal profile of the compressed pulse. Enhanced pulse compression can be achieved by optimizing and selecting the parameters such as collision frequency, ion-temperature, and laser intensity.

  13. Symmetric compression of 'laser greenhouse' targets by a few laser beams

    International Nuclear Information System (INIS)

    Gus'kov, Sergei Yu; Demchenko, N N; Rozanov, Vladislav B; Stepanov, R V; Zmitrenko, N V; Caruso, A; Strangio, C

    2003-01-01

    The possibility of efficient and symmetric compression of a target with a low-density structured absorber by a few laser beams is considered. An equation of state is proposed for a porous medium, which takes into account the special features of the absorption of high-power nanosecond laser pulses. The open version of this target is shown to allow the use of ordinary Gaussian beams, requiring no special profiling of the absorber surface. The conditions are defined under which such targets can be compressed efficiently by only two laser beams (or beam clusters). Simulations show that for a 2.1-MJ laser pulse, a seven-fold gain for the target under study is achieved. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  14. Hydrodynamic instability experiments on the Nova laser

    International Nuclear Information System (INIS)

    Remington, B.A.; Glendinning, S.G.; Kalantar, D.H.

    1996-08-01

    Hydrodynamic instabilities in compressible plasmas play a critical role in the fields of inertial confinement fusion (ICF), astrophysics, and high energy-density physics. We are, investigating hydrodynamic instabilities such as the Rayleigh-Taylor (RT) instability, at high compression at the Nova laser in a series of experiments, both in planar and in spherical geometry. In the indirect drive approach, a thermal x-ray drive is generated by focusing the Nova laser beams into a Au cylindrical radiation cavity (hohlraum). Issues in the instability evolution that we are examining are shock propagation and foil compression, RT growth of 2D versus 3D single-mode perturbations, drive pulse shape, perturbation location at the ablation front versus at an embedded interface, and multimode perturbation growth and nonlinear saturation. The effects of convergence on RT growth are being investigated both with hemispherical implosions of packages mounted on the hohlraum wall and with spherical implosions of capsules at the center of the hohlraum. Single-mode perturbations are pre-imposed at the ablation front of these capsules as a seed for the RT growth. In our direct drive experiments, we are investigating the effect of laser imprinting and subsequent RT growth on planar foils, both at λ Laser = 1/3 μm and 1/2 μm. An overview is given describing recent progress in each of these areas

  15. Direct Laser-Driven Quasi-Isentropic Compression on HEAVEN-I Laser

    International Nuclear Information System (INIS)

    Zhang Pin-Liang; Tang Xiu-Zhang; Li Ye-Jun; Wang Zhao; Tian Bao-Xian; Yin Qian; Lu Ze; Xiang Yi-Huai; Gao Zhi-Xing; Li Jing; Hu Feng-Ming; Gong Zi-Zheng

    2015-01-01

    The HEAVEN-I laser is used for direct drive quasi-isentropic compression up to ∼18 GPa in samples of aluminum without being temporal pulse shaped. The monotonically increasing loading is with a rise time over 17 ns. The compression history is well reproduced by the 1D radiation hydrodynamics simulation. We find that a small shock precursor where the backward integration method cannot process is formed at the beginning of illumination. We compare the loading process of HEAVEN-I with the typical profile (concave down, prefect pulse shape), the results show that a typical profile can obtain more slowly rising and higher pressure, and the shock precursor has significant effects on temperature and entropy production. However, it is demonstrated that the HEAVEN-I is an excellent optical source for direct laser-driven quasi-isentropic compression, even if it produces more temperature rise and entropy than the typical profile. (paper)

  16. Quasi-isentropic Compression of Iron and Magnesium Oxide to 3 Mbar at the Omega Laser Facility

    Science.gov (United States)

    Wang, J.; Smith, R. F.; Coppari, F.; Eggert, J. H.; Boehly, T.; Collins, G.; Duffy, T. S.

    2011-12-01

    Developing a high-pressure, modest temperature ramp compression drive permits exploration of new regions of thermodynamic space, inaccessible through traditional methods of shock or static compression, and of particular relevance to material conditions found in planetary interiors both within and outside our solar system. Ramp compression is a developing technique that allows materials to be compressed along a quasi-isentropic path and provides the ability to study materials in the solid state to higher pressures than can be achieved with diamond anvil cell or shock wave methods. Iron and magnesium oxide are geologically important materials each representative of one of the two major interior regions (core and mantle) of terrestrial planets. An experimental platform for ramp loading of iron (Fe) and magnesium oxide (MgO), has been established and tested in experiments at the Omega Laser Facility, University of Rochester. Omega is a 60-beam ultraviolet (352 nm) neodymium glass laser which is capable of delivery kilojoules of energy in ~10 ns pulses onto targets of a few mm in dimension. In the current experiments, we used a composite ramped laser pulse involving typically 15 beams with total energy of 2.6-3.3 kJ. The laser beams were used to launch spatially planar ramp compression waves into Fe and MgO targets. Each target had four steps that were approximately 5-7 μm thick. Detection of the ramp wave arrival and its velocity at the free surface of each step was made using a VISAR velocity interferometer. Through the use of Lagrangian analysis on the measured wave profiles, stress-density states in iron and magnesium oxide have been determined to pressures of 291 GPa and 260 GPa respectively. For Fe, the α-ɛ transition of iron is overdriven by an initial shock pulse of ~90.1 GPa followed by ramp compression to the peak pressure. The results will be compared with shock compression and diamond anvil cell data for both materials. We acknowledge the Omega staff at

  17. Intra-pulse laser absorption sensor with cavity enhancement for oxidation experiments in a rapid compression machine

    KAUST Repository

    Nasir, Ehson Fawad; Farooq, Aamir

    2018-01-01

    A sensor based on a mid-IR pulsed quantum cascade laser (QCL) and off-axis cavity enhanced absorption spectroscopy (OA-CEAS) has been developed for highly sensitive concentration measurements of carbon monoxide (CO) in a rapid compression machine

  18. Laser drive development for the APS Dynamic Compression Sector

    Science.gov (United States)

    Lagrange, Thomas; Swift, Damian; Reed, Bryan; Bernier, Joel; Kumar, Mukul; Hawreliak, James; Eggert, Jon; Dixit, Sham; Collins, Gilbert

    2013-06-01

    The Dynamic Compression Sector (DCS) at the APS synchrotron offers unprecedented possibilities for x-ray diffraction and scattering measurements in-situ during dynamic loading, including single-shot data collection with x-ray energies high enough (tens of kV) to study high-Z samples in transmission as well as reflection. Dynamic loading induced by laser ablation is an important component of load generation, as the duration, strain rate, and pressure can be controlled via the energy, spot size, and pulse shape. Using radiation hydrodynamics simulations, validated by experiments at several laser facilities, we have investigated the relationship between irradiance history and pressure for ablative loads designed to induce shock and ramp loading in the nanosecond to microsecond range, and including free ablation and also ablation confined by a transparent substrate. We have investigated the effects of lateral release, which constrains the minimum diameter of the focal spot for a given drive duration. In this way, we are able to relate the desired drive conditions to the total laser energy needed, which dictates the laser technologies suitable for a given type of experiment. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  19. Compression measurement in laser driven implosion experiments

    International Nuclear Information System (INIS)

    Attwood, D.T.; Cambell, E.M.; Ceglio, N.M.; Lane, S.L.; Larsen, J.T.; Matthews, D.M.

    1981-01-01

    This paper discusses the measurement of compression in the context of the Inertial Confinement Fusion Programs' transition from thin-walled exploding pusher targets, to thicker walled targets which are designed to lead the way towards ablative type implosions which will result in higher fuel density and pR at burn time. These experiments promote desirable reactor conditions but pose diagnostic problems because of reduced multi-kilovolt x-ray and reaction product emissions, as well as increasingly more difficult transport problems for these emissions as they pass through the thicker pR pusher conditions. Solutions to these problems, pointing the way toward higher energy twodimensional x-ray images, new reaction product imaging ideas and the use of seed gases for both x-ray spectroscopic and nuclear activation techniques are identified

  20. Self-compression of intense short laser pulses in relativistic magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Olumi, M.; Maraghechi, B., E-mail: behrouz@aut.ac.ir [Department of Physics, Amirkabir University of Technology, Post code 15916-34311 Tehran (Iran, Islamic Republic of)

    2014-11-15

    The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrödinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

  1. Diagnostic methods and interpretation of the experiments on microtarget compression in the Iskra-4 device

    International Nuclear Information System (INIS)

    Kochemasov, G.G.

    1992-01-01

    Studies on the problem of laser fusion, which is mainly based on experiments conducted in the Iskra-4 device are reviewed. Different approaches to solution of the problem of DT-fuel ignition, methods of diagnostics of characteristics of laser radiation and plasma, occurring on microtarget heating and compression, are considered

  2. Pulse Compression Techniques for Laser Generated Ultrasound

    Science.gov (United States)

    Anastasi, R. F.; Madaras, E. I.

    1999-01-01

    Laser generated ultrasound for nondestructive evaluation has an optical power density limit due to rapid high heating that causes material damage. This damage threshold limits the generated ultrasound amplitude, which impacts nondestructive evaluation inspection capability. To increase ultrasound signal levels and improve the ultrasound signal-to-noise ratio without exceeding laser power limitations, it is possible to use pulse compression techniques. The approach illustrated here uses a 150mW laser-diode modulated with a pseudo-random sequence and signal correlation. Results demonstrate the successful generation of ultrasonic bulk waves in aluminum and graphite-epoxy composite materials using a modulated low-power laser diode and illustrate ultrasound bandwidth control.

  3. Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas.

    Science.gov (United States)

    Gotchev, O V; Knauer, J P; Chang, P Y; Jang, N W; Shoup, M J; Meyerhofer, D D; Betti, R

    2009-04-01

    A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity-a way of reaching higher gains than is possible with conventional ICF.

  4. Time resolved x-ray pinhole photography of compressed laser fusion targets

    International Nuclear Information System (INIS)

    Attwood, D.T.

    1976-01-01

    Use of the Livermore x-ray streak camera to temporally record x-ray pinhole images of laser compressed targets is described. Use is made of specially fabricated composite x-ray pinholes which are near diffraction limited for 6 A x-rays, but easily aligned with a He--Ne laser of 6328 A wavelength. With a 6 μm x-ray pinhole, the overall system can be aligned to 5 μm accuracy and provides implosion characteristics with space--time resolutions of approximately 6 μm and 15 psec. Acceptable criteria for pinhole alignment, requisite x-ray flux, and filter characteristics are discussed. Implosion characteristics are presented from our present experiments with 68 μm diameter glass microshell targets and 0.45 terawatt, 70 psec Nd laser pulses. Final implosion velocities in excess of 3 x 10 7 cm/sec are evident

  5. Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

    Science.gov (United States)

    Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

    2018-02-01

    A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

  6. Laser driven supersonic flow over a compressible foam surface on the Nike lasera)

    Science.gov (United States)

    Harding, E. C.; Drake, R. P.; Aglitskiy, Y.; Plewa, T.; Velikovich, A. L.; Gillespie, R. S.; Weaver, J. L.; Visco, A.; Grosskopf, M. J.; Ditmar, J. R.

    2010-05-01

    A laser driven millimeter-scale target was used to generate a supersonic shear layer in an attempt to create a Kelvin-Helmholtz (KH) unstable interface in a high-energy-density (HED) plasma. The KH instability is a fundamental fluid instability that remains unexplored in HED plasmas, which are relevant to the inertial confinement fusion and astrophysical environments. In the experiment presented here the Nike laser [S. P. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to create and drive Al plasma over a rippled foam surface. In response to the supersonic Al flow (Mach=2.6±1.1) shocks should form in the Al flow near the perturbations. The experimental data were used to infer the existence and location of these shocks. In addition, the interface perturbations show growth that has possible contributions from both KH and Richtmyer-Meshkov instabilities. Since compressible shear layers exhibit smaller growth, it is important to use the KH growth rate derived from the compressible dispersion relation.

  7. SBS pulse compression applied to a commercial Q-switch Nd-YAG laser

    International Nuclear Information System (INIS)

    Aliaga-Rossel, R.; Bayley, J.; Mamin, A.; Nizienko, Y.

    1997-01-01

    In optical diagnosis of dense Z-pinches, sub-nanosecond laser pulses are required in order to freeze the movement of the plasma during the probing. Commercial lasers can provide such type of pulses but they are either very expensive, or they have a very low energy per pulse. A technique that uses Stimulated Brillouin Scattering (SBS) to compress a 8 ns pulse of a commercial Q-switched Nd-YAG laser is reported here. To carry out this passive compression technique, a frequency doubled laser pulse of 10 ns was focused into a single SBS gas cell, 2 m long, filled with a mixture of argon and sulphurhexafluoride (SF 6 ) at a total pressure of 40 bar. A shorter and high intensity pulse was reflected from the cell (created by SBS) and it travelled back along its original path until it was separated from its original direction by using a dichroic polariser. The pumping volume of the SBS cell, the convergence of the incident beam and the pressure of the gas cell, were optimised to maximise both temporal compression and the output energy. Pulses of 10 ns were compressed to less than 400 ps with a conversion efficiency of 80%. This SBS pulse compression system has been used to make most of the optical measurements of a dense fibre pinch plasma produced in the MAGPIE generator

  8. Investigation of the compression of high-aspect targets irradiated with a laser pulse of the second harmonic of the Iskra-4 iodine laser

    International Nuclear Information System (INIS)

    Bel'kov, S.A.; Bessarab, A.V.; Voronich, I.N.; Garanin, S.G.; Dolgoleva, G.V.; Zaretskii, A.I.; Izgorodin, V.M.; Ilyushechkin, B.N.; Kochemasov, G.G.; Kunin, A.V.; Martynenko, S.P.; Merkulov, S.G.; Rukavishnikov, N.N.; Ryadov, A.V.; Suslov, N.A.; Sukharev, S.A.

    1992-01-01

    Theoretical modeling of experiments on the compression of targets under exploding pusher shell conditions, carried out at the Iskra-4 facility with the iodine laser pulsed at its fundamental frequency (λ= 1.315 μm) showed a correlation between the increase in the discrepancy between the calculated and experimental neutron yields and increase of the aspect ratio of the shell of the target used in the experiment. After conversion of the Iskra-4 facility to generate the second harmonic and improving the beam uniformity in the region of the target, a series of experiments was carried out on the compression of high-aspect targets A s > 300. In this series a record neutron yield for this installation, N = 6 x 10 7 , was obtained in experiments with glass-shell targets

  9. Equation of state of laser-shocked compressed iron; Equation d'etat du fer comprime par choc laser

    Energy Technology Data Exchange (ETDEWEB)

    Huser, G

    2004-01-01

    This thesis enters the field of highly compressed materials equation of state studies. In particular, it focuses on the case of laser shock compressed iron. This work indeed aims at getting to the conditions of the earth's core, comprising a solid inner core and a liquid outer core. The understanding of phenomena governing the core's thermodynamics and the geodynamic process requires the knowledge of iron melting line locus around the solid-liquid interface at 3.3 Mbar. Several experiments were performed to that extent. First, an absolute measurement of iron Hugoniot was obtained. Following is a study of partially released states of iron into a window material: lithium fluoride (LiF). This configuration enables direct access to compressed iron optical properties such as reflectivity and self-emission. Interface velocity measurement is dominated by compressed LiF optical properties and is used as a pressure gauge. Using a dual wavelength reflectivity diagnostic, compressed iron electrical conductivity was estimated and found to be in good agreement with previous results found in geophysics literature. Self-emission diagnostic was used to measure temperature of partially released iron and revealed a solid-liquid phase transition at Mbar pressures. (author)

  10. Laser-excited optical emission response of CdTe quantum dot/polymer nanocomposite under shock compression

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Kang, Zhitao; Summers, Christopher J. [Phosphor Technology Center of Excellence, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); Bansihev, Alexandr A.; Christensen, James M.; Dlott, Dana D. [School of Chemical Sciences and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Breidenich, Jennifer; Scripka, David A.; Thadhani, Naresh N. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Zhou, Min, E-mail: min.zhou@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States)

    2016-01-04

    Laser-driven shock compression experiments and corresponding finite element method simulations are carried out to investigate the blueshift in the optical emission spectra under continuous laser excitation of a dilute composite consisting of 0.15% CdTe quantum dots by weight embedded in polyvinyl alcohol polymer. This material is a potential candidate for use as internal stress sensors. The analyses focus on the time histories of the wavelength blue-shift for shock loading with pressures up to 7.3 GPa. The combined measurements and calculations allow a relation between the wavelength blueshift and pressure for the loading conditions to be extracted. It is found that the blueshift first increases with pressure to a maximum and subsequently decreases with pressure. This trend is different from the monotonic increase of blueshift with pressure observed under conditions of quasistatic hydrostatic compression. Additionally, the blueshift in the shock experiments is much smaller than that in hydrostatic experiments at the same pressure levels. The differences in responses are attributed to the different stress states achieved in the shock and hydrostatic experiments and the time dependence of the mechanical response of the polymer in the composite. The findings offer a potential guide for the design and development of materials for internal stress sensors for shock conditions.

  11. Experiments with automata compression

    NARCIS (Netherlands)

    Daciuk, J.; Yu, S; Daley, M; Eramian, M G

    2001-01-01

    Several compression methods of finite-state automata are presented and evaluated. Most compression methods used here are already described in the literature. However, their impact on the size of automata has not been described yet. We fill that gap, presenting results of experiments carried out on

  12. Cascaded quadratic soliton compression of high-power femtosecond fiber lasers in Lithium Niobate crystals

    DEFF Research Database (Denmark)

    Bache, Morten; Moses, Jeffrey; Wise, Frank W.

    2008-01-01

    The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs.......The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs....

  13. Gaseous laser targets and optical diagnostics for studying compressible hydrodynamic instabilities

    International Nuclear Information System (INIS)

    Edwards, J M; Robey, H; Mackinnon, A

    2001-01-01

    Explore the combination of optical diagnostics and gaseous targets to obtain important information about compressible turbulent flows that cannot be derived from traditional laser experiments for the purposes of V and V of hydrodynamics models and understanding scaling. First year objectives: Develop and characterize blast wave-gas jet test bed; Perform single pulse shadowgraphy of blast wave interaction with turbulent gas jet as a function of blast wave Mach number; Explore double pulse shadowgraphy and image correlation for extracting velocity spectra in the shock-turbulent flow interaction; and Explore the use/adaptation of advanced diagnostics

  14. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, M. J., E-mail: mros@lle.rochester.edu; Li, C. K.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Fox, W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Igumenshchev, I.; Stoeckl, C.; Glebov, V. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Town, R. P. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-04-15

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β ∼ 10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  15. Characterization of particle deformation during compression measured by confocal laser scanning microscopy.

    Science.gov (United States)

    Guo, H X; Heinämäki, J; Yliruusi, J

    1999-09-20

    Direct compression of riboflavin sodium phosphate tablets was studied by confocal laser scanning microscopy (CLSM). The technique is non-invasive and generates three-dimensional (3D) images. Tablets of 1% riboflavin sodium phosphate with two grades of microcrystalline cellulose (MCC) were individually compressed at compression forces of 1.0 and 26.8 kN. The behaviour and deformation of drug particles on the upper and lower surfaces of the tablets were studied under compression forces. Even at the lower compression force, distinct recrystallized areas in the riboflavin sodium phosphate particles were observed in both Avicel PH-101 and Avicel PH-102 tablets. At the higher compression force, the recrystallization of riboflavin sodium phosphate was more extensive on the upper surface of the Avicel PH-102 tablet than the Avicel PH-101 tablet. The plastic deformation properties of both MCC grades reduced the fragmentation of riboflavin sodium phosphate particles. When compressed with MCC, riboflavin sodium phosphate behaved as a plastic material. The riboflavin sodium phosphate particles were more tightly bound on the upper surface of the tablet than on the lower surface, and this could also be clearly distinguished by CLSM. Drug deformation could not be visualized by other techniques. Confocal laser scanning microscopy provides valuable information on the internal mechanisms of direct compression of tablets.

  16. Method and device for the powerful compression of laser-produced plasmas for nuclear fusion

    International Nuclear Information System (INIS)

    Hora, H.

    1975-01-01

    According to the invention, more than 10% of the laser energy are converted into mechanical energy of compression, in that the compression is produced by non-linear excessive radiation pressure. The time and local spectral and intensity distribution of the laser pulse must be controlled. The focussed laser beams must increase to over 10 15 W/cm 2 in less than 10 -9 seconds and the time variation of the intensities must be carried out so that the dynamic absorption of the outer plasma corona by rippling consumes less than 90% of the laser energy. (GG) [de

  17. Tamper temperature and compression from simultaneous proton and alpha-particle measurements in laser fusion experiments

    International Nuclear Information System (INIS)

    Cover, R.A.; Kubis, J.J.; Mayer, F.J.; Slater, D.C.

    1978-01-01

    The energy loss per unit path length for a charged particle incident on a spatially uniform isothermal Maxwellian plasma is a function of the temperature and density of the medium. Within this model the temperature and compression rhoΔr of the tamper of a laser-driven microshell target can be accurately determined, in the absence of electrostatic acceleration, by the simultaneous measurement of the energy loss from 3.52-MeV α particles from D-T reactions and 3.02-MeV protons from D-D reactions

  18. Gain compression and its dependence on output power in quantum dot lasers

    Science.gov (United States)

    Zhukov, A. E.; Maximov, M. V.; Savelyev, A. V.; Shernyakov, Yu. M.; Zubov, F. I.; Korenev, V. V.; Martinez, A.; Ramdane, A.; Provost, J.-G.; Livshits, D. A.

    2013-06-01

    The gain compression coefficient was evaluated by applying the frequency modulation/amplitude modulation technique in a distributed feedback InAs/InGaAs quantum dot laser. A strong dependence of the gain compression coefficient on the output power was found. Our analysis of the gain compression within the frame of the modified well-barrier hole burning model reveals that the gain compression coefficient decreases beyond the lasing threshold, which is in a good agreement with the experimental observations.

  19. Strategies for Time-resolved X-ray Diffraction of Phase Transitions with Laser Compression

    Science.gov (United States)

    Benedetti, Laura Robin; Eggert, J. H.; Bradley, D. K.; Bell, P. M.; Kilkenny, J. D.; Palmer, N.; Petre, R. B.; Rygg, J. R.; Sorce, C.; Collins, G. W.; Boehly, T. R.

    2017-10-01

    As part of a program to document kinetics of phase transitions under laser-driven dynamic compression, we are designing a platform to make multiple x-ray diffraction measurements during a single laser experiment. Our plans include experimental development at Omega-EP and eventual implementation at NIF. We will present our strategy for designing a robust platform that can effectively document a wide variety of phase transformations by utilizing both streaked and multiple-frame imaging detectors. Preliminary designs utilize a novel CMOS detector designed by Sandia National Lab. Our initial experiments include scoping studies that will focus on photometrics and shielding requirements in the high EMP environment close to the target. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC, LLNL-ABS-734470.

  20. Compressing and focusing a short laser pulse by a thin plasma lens

    International Nuclear Information System (INIS)

    Ren, C.; Duda, B. J.; Hemker, R. G.; Mori, W. B.; Katsouleas, T.; Antonsen, T. M.; Mora, P.

    2001-01-01

    We consider the possibility of using a thin plasma slab as an optical element to both focus and compress an intense laser pulse. By thin we mean that the focal length is larger than the lens thickness. We derive analytic formulas for the spot size and pulse length evolution of a short laser pulse propagating through a thin uniform plasma lens. The formulas are compared to simulation results from two types of particle-in-cell code. The simulations give a greater final spot size and a shorter focal length than the analytic formulas. The difference arises from spherical aberrations in the lens which lead to the generation of higher-order vacuum Gaussian modes. The simulations also show that Raman side scattering can develop. A thin lens experiment could provide unequivocal evidence of relativistic self-focusing

  1. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    Pisani, F.

    2000-02-01

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  2. High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

    International Nuclear Information System (INIS)

    Voronin, A. A.; Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A.; Zheltikov, A. M.

    2011-01-01

    Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-μm laser pulses in high-pressure argon.

  3. Process and application of shock compression by nanosecond pulses of frequency-doubled Nd:YAG laser

    Science.gov (United States)

    Sano, Yuji; Kimura, Motohiko; Mukai, Naruhiko; Yoda, Masaki; Obata, Minoru; Ogisu, Tatsuki

    2000-02-01

    The authors have developed a new process of laser-induced shock compression to introduce a residual compressive stress on material surface, which is effective for prevention of stress corrosion cracking (SCC) and enhancement of fatigue strength of metal materials. The process developed is unique and beneficial. It requires no pre-conditioning for the surface, whereas the conventional process requires that the so-called sacrificial layer is made to protect the surface from damage. The new process can be freely applied to water- immersed components, since it uses water-penetrable green light of a frequency-doubled Nd:YAG laser. The process developed has the potential to open up new high-power laser applications in manufacturing and maintenance technologies. The laser-induced shock compression process (LSP) can be used to improve a residual stress field from tensile to compressive. In order to understand the physics and optimize the process, the propagation of a shock wave generated by the impulse of laser irradiation and the dynamic response of the material were analyzed by time-dependent elasto-plastic calculations with a finite element program using laser-induced plasma pressure as an external load. The analysis shows that a permanent strain and a residual compressive stress remain after the passage of the shock wave with amplitude exceeding the yield strength of the material. A practical system materializing the LSP was designed, manufactured, and tested to confirm the applicability to core components of light water reactors (LWRs). The system accesses the target component and remotely irradiates laser pulses to the heat affected zone (HAZ) along weld lines. Various functional tests were conducted using a full-scale mockup facility, in which remote maintenance work in a reactor vessel could be simulated. The results showed that the system remotely accessed the target weld lines and successfully introduced a residual compressive stress. After sufficient training

  4. Laser fusion research with GEKKO XII and PW laser system at Osaka

    International Nuclear Information System (INIS)

    Izawa, Y.; Mima, K.; Azechi, H.; Fujioka, S.; Fujita, H.; Fujimoto, Y.; Jitsuno, T.; Johzaki, Y.; Kitagawa, Y.; Kodama, R.; Kondo, K.; Miyanaga, N.; Nagai, K.; Nagatomo, H.; Nakai, M.; Nishihara, K.; Nishimura, H.; Norimatsu, T.; Shiraga, H.; Shigemori, K.; Sunahara, A.; Tanaka, K.A.; Tsubakimoto, K.; Nakao, Y.; Norreys, P.; Sakagami, H.

    2005-01-01

    Fast heating of the compressed core plasma up to 500eV has been successfully demonstrated by injecting a 400J/0.6ps PW laser into a compressed CD shell through a hollow gold cone. According to this result, we started the FIREX (Fast Ignition Realization Experiment) project toward demonstrating the ignition of the highly compressed DT fuel by the high energy PW laser heating. A new heating laser LFEX (Laser for Fast Ignition Experiment) is under construction. In this paper the progresses in the experimental studies on scientific issues related to fast ignition and the integrated code development toward the FIREX will be reported. Research results on implosion hydrodynamics, Rayleigh-Taylor instability growth and a new stabilization mechanism are also reported. (author)

  5. Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

    KAUST Repository

    Nasir, Ehson Fawad

    2016-07-16

    A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm were operated in pulsed mode, causing a frequency "down-chirp" across two ro-vibrational transitions of carbon monoxide. The down-chirp phenomenon resulted in large spectral tuning (δν ∼2.8cm-1) within a single pulse of each laser at a high pulse repetition frequency (100kHz). The wide tuning range allowed the application of the two-line thermometry technique, thus making the sensor quantitative and calibration-free. The sensor was first tested in non-reactive CO-N2 gas mixtures in the RCM and then applied to cases of n-pentane oxidation. Experiments were carried out for end of compression (EOC) pressures and temperatures ranging 9.21-15.32bar and 745-827K, respectively. Measured EOC temperatures agreed with isentropic calculations within 5%. Temperature rise measured during the first-stage ignition of n-pentane is over-predicted by zero-dimensional kinetic simulations. This work presents, for the first time, highly time-resolved temperature measurements in reactive and non-reactive rapid compression machine experiments. © 2016 Elsevier Ltd.

  6. Hugoniot and refractive indices of bromoform under shock compression

    Science.gov (United States)

    Liu, Q. C.; Zeng, X. L.; Zhou, X. M.; Luo, S. N.

    2018-01-01

    We investigate physical properties of bromoform (liquid CHBr3) including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity-particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ˜21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ˜26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

  7. Hugoniot and refractive indices of bromoform under shock compression

    Directory of Open Access Journals (Sweden)

    Q. C. Liu

    2018-01-01

    Full Text Available We investigate physical properties of bromoform (liquid CHBr3 including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity−particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ∼21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ∼26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

  8. Self-protecting nonlinear compression in a solid fiber for long-term stable ultrafast lasers at 2 μm wavelength

    Science.gov (United States)

    Stutzki, Fabian; Gaida, Christian; Gebhardt, Martin; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas; Pupeza, Ioachim

    2017-02-01

    Ultrashort-pulse laser systems are an enabling technology for numerous applications. The stability of such systems is especially crucial for frequency metrology and high precision spectroscopy. Thulium-based fiber lasers are an ideal starting point as a reliable and yet powerful source for the nonlinear conversion towards the mid-IR region. Recently, we have demonstrated that nonlinear self-compression in a fused silica solid-core fiber allows for few-cycle pulse duration with up to 24 MW peak power using a high-repetition rate thulium-based fiber laser system operating at around 2 μm wavelength [1]. This experiment operates near the self-focusing limit of about 24 MW for circular polarization, which increases the requirements for the system stability due to the risk of a fiber damage. Here, we present a self-protecting nonlinear compression regime allowing for long-term operation and high output-pulse stability with very similar output performance.

  9. Effect of applied stress on the compressive residual stress introduced by laser peening

    International Nuclear Information System (INIS)

    Sumiya, Rie; Tazawa, Toshiyuki; Narazaki, Chihiro; Saito, Toshiyuki; Kishimoto, Kikuo

    2016-01-01

    Peening is the process which is able to be generated compressive residual stress and is known to be effective for preventing SCC initiation and improvement of fatigue strength. Laser peening is used for the nuclear power plant components in order to prevent SCC initiation. Although it is reported that the compressive residual stress decreases due to applied stresses under general operating condition, the change of residual stress might be large under excessive loading such as an earthquake. The objectives of this study are to evaluate the relaxation behavior of the compressive residual stress due to laser peening and to confirm the surface residual stress after loading. Therefore laser peened round bar test specimens of SUS316L which is used for the reactor internals of nuclear power plant were loaded at room temperature and elevated temperature and then surface residual stresses were measured by X-ray diffraction method. In the results of this test, it was confirmed that the compressive residual stress remained after applying uniform stress larger than 0.2% proof stress, and the effect of cyclic loading on the residual stress was small. The effect of applying compressive stress on the residual stress relaxation was confirmed to be less than that of applying tensile stress. Plastic deformation through a whole cross section causes the change in the residual stress distribution. As a result, the surface compressive residual stress is released. It was shown that the effect of specimen size on residual stress relaxation and the residual stress relaxation behavior in the stress concentration region can be explained by assumed stress relaxation mechanism. (author)

  10. Efficient compression of the femtosecond pulses of an ytterbium laser in a gas-filled capillary

    International Nuclear Information System (INIS)

    Konyashchenko, Aleksandr V; Losev, Leonid L; Tenyakov, S Yu

    2011-01-01

    A 290-fs radiation pulse of an ytterbium laser system with a central wavelength of 1028 nm and an energy of 145 μJ was compressed to a 27-fs pulse with an energy of 75 μJ. The compression was realised on the basis of the effect of pulse spectrum broadening in a xenon-filled glass capillary for a pulse repetition rate of 3kHz. (control of laser radiation parameters)

  11. [Experiments on the OMEGA Laser System]. LLE Review. Quarterly report, July-September 1985. Volume 24

    International Nuclear Information System (INIS)

    Skupsky, S.

    1985-01-01

    This volume of the LLE Review contains articles on the first 24-beam uv experiments on the OMEGA laser system, the use of absorption spectroscopy to diagnose high-density compressions, the development of a new target fabrication technique to coat mechanically unsupported laser-fusion targets with a parylene layer, the use of liquid crystals as laser-beam apodizers, the investigation of the process of melting using a subpicosecond probe, the development of a new picosecond oscilloscope, and the National Laser Users Facility activities for June-September 1985. 80 refs., 36 figs

  12. Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

    DEFF Research Database (Denmark)

    Bache, Morten; Wise, Frank W.

    2010-01-01

    The output pulses of a commercial high-power femtosecond fiber laser or amplifier are typically around 300–500 fs with wavelengths of approximately 1030 nm and tens of microjoules of pulse energy. Here, we present a numerical study of cascaded quadratic soliton compression of such pulses in LiNbO3....... However, the strong group-velocity dispersion implies that the pulses can achieve moderate compression to durations of less than 130 fs in available crystal lengths. Most of the pulse energy is conserved because the compression is moderate. The effects of diffraction and spatial walk-off are addressed......, and in particular the latter could become an issue when compressing such long crystals (around 10 cm long). We finally show that the second harmonic contains a short pulse locked to the pump and a long multi-picosecond red-shifted detrimental component. The latter is caused by the nonlocal effects...

  13. Compression experiments on the TOSKA tokamak

    International Nuclear Information System (INIS)

    Cima, G.; McGuire, K.M.; Robinson, D.C.; Wootton, A.J.

    1980-10-01

    Results from minor radius compression experiments on a tokamak plasma in TOSCA are reported. The compression is achieved by increasing the toroidal field up to twice its initial value in 200μs. Measurements show that particles and magnetic flux are conserved. When the initial energy confinement time is comparable with the compression time, energy gains are greater than for an adiabatic change of state. The total beta value increases. Central beta values approximately 3% are measured when a small major radius compression is superimposed on a minor radius compression. Magnetic field fluctuations are affected: both the amplitude and period decrease. Starting from low energy confinement times, approximately 200μs, increases in confinement times up to approximately 1 ms are measured. The increase in plasma energy results from a large reduction in the power losses during the compression. When the initial energy confinement time is much longer than the compression time, the parameter changes are those expected for an adiabatic change of state. (author)

  14. Simultaneous broadband laser ranging and photonic Doppler velocimetry for dynamic compression experiments

    Energy Technology Data Exchange (ETDEWEB)

    La Lone, B. M., E-mail: lalonebm@nv.doe.gov; Marshall, B. R.; Miller, E. K.; Stevens, G. D.; Turley, W. D. [National Security Technologies, LLC, Special Technologies Laboratory, Santa Barbara, California 93111 (United States); Veeser, L. R. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

    2015-02-15

    A diagnostic was developed to simultaneously measure both the distance and velocity of rapidly moving surfaces in dynamic compression experiments, specifically non-planar experiments where integrating the velocity in one direction does not always give the material position accurately. The diagnostic is constructed mainly from fiber-optic telecommunications components. The distance measurement is based on a technique described by Xia and Zhang [Opt. Express 18, 4118 (2010)], which determines the target distance every 20 ns and is independent of the target speed. We have extended the full range of the diagnostic to several centimeters to allow its use in dynamic experiments, and we multiplexed it with a photonic Doppler velocimetry (PDV) system so that distance and velocity histories can be measured simultaneously using one fiber-optic probe. The diagnostic was demonstrated on a spinning square cylinder to show how integrating a PDV record can give an incorrect surface position and how the ranging diagnostic described here obtains it directly. The diagnostic was also tested on an explosive experiment where copper fragments and surface ejecta were identified in both the distance and velocity signals. We show how the distance measurements complement the velocity data. Potential applications are discussed.

  15. Isentropic/shock compression and recovery methodology for materials using high-amplitude laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Maddox, B.R., E-mail: maddox3@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Park, H.-S., E-mail: park1@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Lu, C.-H., E-mail: chiahuilu@gmail.com [University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093 (United States); Remington, B.A., E-mail: remington2@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Prisbrey, S., E-mail: prisbrey1@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Kad, B., E-mail: bkad@ucsd.edu [University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093 (United States); Luo, R., E-mail: luorwga@gmail.com [General Atomics, 3483 Dunhill Street, San Diego, CA 92121-1200 (United States); Meyers, M.A., E-mail: mameyers@eng.ucsd.edu [University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093 (United States)

    2013-08-20

    Abstarct: A new method of subjecting samples to high-amplitude laser pulses with durations in the ns range and recovering them for characterization is presented. It is applied to tantalum monocrystals and nanocrystals that are subjected to controlled and prescribed ramp loading configurations, creating a quasi-isentropic loading in the front that is retained up to 40 μm into the specimen. This is enabled by the use of a reservoir into which six laser beams impinge simultaneously, thereby creating plasma in a reservoir, from which the pulse is launched into the metal. This technique enables, with proper wave trapping devices, the recovery of the specimens for subsequent characterization. Successful experiments conducted in the Laboratory for Laser Energetics, U. of Rochester, generated pressure pulses with initial amplitudes ranging from 15 to 110 GPa and initial durations of ∼3 ns. The quasi-isotropic loading minimizes thermal effects at the front surface. The compression history of the recovered samples is measured using velocity interferometry from an Al-coated LiF witness target on the same shot driven by a separate, but equivalent set of laser beams. These experimental measurements are compared with computations using a radiation hydrodynamics code. Recovered samples are investigated using optical, scanning, and transmission electron microscopy. The laser damage to the surface is characterized.

  16. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    Energy Technology Data Exchange (ETDEWEB)

    Teng, J.; Gu, Y.Q., E-mail: tengjian@mail.ustc.edu.cn; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

    2013-11-21

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

  17. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    Science.gov (United States)

    Teng, J.; Gu, Y. Q.; Zhu, B.; Hong, W.; Zhao, Z. Q.; Zhou, W. M.; Cao, L. F.

    2013-11-01

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

  18. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    International Nuclear Information System (INIS)

    Teng, J.; Gu, Y.Q.; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

    2013-01-01

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator

  19. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

    Science.gov (United States)

    Fujioka, Shinsuke; Arikawa, Yasunobu; Kojima, Sadaoki; Johzaki, Tomoyuki; Nagatomo, Hideo; Sawada, Hiroshi; Lee, Seung Ho; Shiroto, Takashi; Ohnishi, Naofumi; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Zhang, Zhe; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Mima, Kunioki; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki; Kawanaka, Junji; Jitsuno, Takahisa; Miyanaga, Noriaki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kondo, Kotaro; Bailly-Grandvaux, Mathieu; Bellei, Claudio; Santos, João Jorge; Azechi, Hiroshi

    2016-05-01

    A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKO-XII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >109. Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding

  20. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Fujioka, Shinsuke, E-mail: sfujioka@ile.osaka-u.ac.jp; Arikawa, Yasunobu; Kojima, Sadaoki; Nagatomo, Hideo; Lee, Seung Ho; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 Japan (Japan); and others

    2016-05-15

    A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKO-XII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser–plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >10{sup 9}. Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused

  1. Design, Construction and Calibration of a Near-Infrared Four-Color Pyrometry System for Laser-Driven High Pressure Experiments

    Science.gov (United States)

    Ali, S. J.; Jeanloz, R.; Collins, G.; Spaulding, D. K.

    2010-12-01

    Current dynamic compression experiments, using both quasi-isentropic and shock-compression, allow access to pressure-temperature states both on and off the principle Hugoniot and over a wide range of conditions of direct relevance to planetary interiors. Such studies necessitate reliable temperature measurements below 4000-5000 K. Such relatively low temperature states are also of particular interest for materials such as methane and water that do not experience much heating under shock compression. In order to measure these temperatures as a function of time across the sample, a four-color, near-infrared pyrometry system is being developed for use at the Janus laser facility (LLNL) with channels at wavelengths of 932nm-1008nm, 1008nm-1108nm, 1108nm-1208nm, and 1208nm-1300nm. Each color band is fiber-coupled to an InGaAs PIN photodiode with a rise time of less than 60 ps, read using an 18 GHz oscilloscope in order to ensure time resolutions of under 200 ps. This will allow for high temporal resolution measurements of laser-driven shock compression experiments with total durations of 5-15 ns as well as correlation with simultaneous time-resolved velocity interferometry and visual-wavelength pyrometry. Calibration of the system is being accomplished using quartz targets, as the EOS for quartz is well known, along with a calibrated integrating sphere of known spectral radiance.

  2. LSP Simulations of the Neutralized Drift Compression Experiment

    CERN Document Server

    Thoma, Carsten H; Gilson, Erik P; Henestroza, Enrique; Roy, Prabir K; Welch, Dale; Yu, Simon

    2005-01-01

    The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory involves the longitudinal compression of a singly-stripped K ion beam with a mean energy of 250 keV in a meter long plasma. We present simulation results of compression of the NDCX beam using the PIC code LSP. The NDCX beam encounters an acceleration gap with a time-dependent voltage that decelerates the front and accelerates the tail of a 500 ns pulse which is to be compressed 110 cm downstream. The simulations model both ideal and experimental voltage waveforms. Results show good longitudinal compression without significant emittance growth.

  3. Plasma experiments with 1.06-μm lasers at the Lawrence Livermore Laboratory

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.; Holzrichter, J.F.; Manes, K.R.; Storm, E.K.; Boyle, M.J.; Brooks, K.M.; Haas, R.A.; Phillion, D.W.; Rupert, V.C.

    1976-01-01

    Recent laser fusion experiments at the Lawrence Livermore Laboratory have provided basic data concerning: laser beam propagation and absorption in high temperature plasmas, electron energy transport processes that transfer the absorbed laser energy to the high-density ablation region, the general fluid dynamic expansion and compression of the heated plasma, and the processes responsible for the production of 14-MeV neutrons during implosion experiments. Irradiation experiments were performed with Nd:YAG glass laser systems: the two-beam Janus (less than or equal to40 J/100 ps, approx.0.4 TW) and Argus (less than or equal to140 J, 35 ps, approx.4 TW), and the single beam Cyclops (less than or equal to70 J/100 ps, approx.0.7 TW). Two classes of targets have been used: glass microshells (approx.40 to 120 μm in diameter with approx.0.75-μm-thick walls) filled with an equimolar deuterium-tritium mixture, and disks (approx.160 to 600 μm in diameter and approx. 10 μm thick) of several compositions. The targets were supported in vacuum (pressure less than or equal to10 -5 Torr) by thin glass stalks. This paper reports on results related to the propagation, absorption, and scattering of laser light by both spherical and planar targets

  4. The use of lasers to compress matter

    International Nuclear Information System (INIS)

    Billon, D.; Cognard, D.; Launspach, J.; Patou, D.; Redon, D.; Rocchioccioli, J.L.; Schirmann, D.

    1975-01-01

    On account of great progress realized in the technology of powerful lasers during recent years, it well be possible at some future date, to use them to implode small targets of fusible materials, and to produce thermonuclear controlled fusion. Through experiments carried out at Limeil, it is shown that laser energy can produce great pressures in solids. Particularly, the focusing of several laser beams on a target produces inside it a convergent shock wave [fr

  5. Soviet paper on laser target heating, symmetry of irradiation, and two-dimensional effects on compression

    International Nuclear Information System (INIS)

    Sahlin, H.L.

    1976-01-01

    Included is a paper presented at the Annual Meeting of the Plasma Physics Division of the American Physical Society in San Francisco on November 19, 1976. The paper discusses some theoretical problems of laser target irradiation and compression investigated at the laboratory of quantum radiophysics of Lebedev Physical Institute. Of significant interest was the absorption and reflection of laser radiation in the corona plasma of a laser target

  6. Application of Compressive Sensing to Gravitational Microlensing Experiments

    Science.gov (United States)

    Korde-Patel, Asmita; Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is an emerging technology for data compression and simultaneous data acquisition. This is an enabling technique for significant reduction in data bandwidth, and transmission power and hence, can greatly benefit spaceflight instruments. We apply this process to detect exoplanets via gravitational microlensing. We experiment with various impact parameters that describe microlensing curves to determine the effectiveness and uncertainty caused by Compressive Sensing. Finally, we describe implications for spaceflight missions.

  7. Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

    CERN Document Server

    Pompili, Riccardo; Bellaveglia, M; Biagioni, A; Castorina, G; Chiadroni, E; Cianchi, A; Croia, M; Di Giovenale, D; Ferrario, M; Filippi, F; Gallo, A; Gatti, G; Giorgianni, F; Giribono, A; Li, W; Lupi, S; Mostacci, A; Petrarca, M; Piersanti, L; Di Pirro, G; Romeo, S; Scifo, J; Shpakov, V; Vaccarezza, C; Villa, F

    2017-01-01

    The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC_LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations.

  8. Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

    International Nuclear Information System (INIS)

    Pompili, R; Anania, M P; Bellaveglia, M; Biagioni, A; Castorina, G; Chiadroni, E; Croia, M; Giovenale, D Di; Ferrario, M; Gallo, A; Gatti, G; Cianchi, A; Filippi, F; Giorgianni, F; Giribono, A; Lupi, S; Mostacci, A; Petrarca, M; Piersanti, L; Li, W

    2016-01-01

    The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC-LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations. (paper)

  9. Magnetic field effects on ultrafast lattice compression dynamics of Si(111) crystal when excited by linearly-polarized femtosecond laser pulses

    Science.gov (United States)

    Hatanaka, Koji; Odaka, Hideho; Ono, Kimitoshi; Fukumura, Hiroshi

    2007-03-01

    Time-resolved X-ray diffraction measurements of Si (111) single crystal are performed when excited by linearly-polarized femtosecond laser pulses (780 nm, 260 fs, negatively-chirped, 1 kHz) under a magnetic field (0.47 T). Laser fluence on the sample surface is 40 mJ/cm^2, which is enough lower than the ablation threshold at 200 mJ/cm^2. Probing X-ray pulses of iron characteristic X-ray lines at 0.193604 and 0.193998 nm are generated by focusing femtosecond laser pulses onto audio-cassette tapes in air. Linearly-polarized femtosecond laser pulse irradiation onto Si(111) crystal surface induces transient lattice compression in the picosecond time range, which is confirmed by transient angle shift of X-ray diffraction to higher angles. Little difference of compression dynamics is observed when the laser polarization is changed from p to s-pol. without a magnetic field. On the other hand, under a magnetic field, the lattice compression dynamics changes when the laser is p-polarized which is vertical to the magnetic field vector. These results may be assigned to photo-carrier formation and energy-band distortion.

  10. The dynamics of pulse compression in synchronously pumped fiber Raman lasers

    International Nuclear Information System (INIS)

    Band, Y.B.; Ackerhalt, J.R.; Heller, D.F.

    1990-01-01

    Dynamical equations describing the amplification and propagation of an initial Stokes seed pulse in a synchronously pumped fiber Raman laser configuration are formulated and analytic solutions are derived. A train of Stokes shifted pulses are produced, whose individual characteristics eventually evolve on successive round-trips through the fiber into subpicosecond pulses having constant fluence and decreasing temporal duration. Raman pulse compression stops when it is counterbalanced by the effects of group velocity dispersion and phase modulation in the normal dispersion regime. Pulse breakup due to soliton formation can occur in the anomalous dispersion regime. Simple expressions for the rate of pulse compression, steady-state pulse fluence, and for the minimum steady-state pulse duration are obtained

  11. On the characterisation of the dynamic compressive behaviour of silicon carbides subjected to isentropic compression experiments

    Directory of Open Access Journals (Sweden)

    Zinszner Jean-Luc

    2015-01-01

    Full Text Available Ceramic materials are commonly used as protective materials particularly due to their very high hardness and compressive strength. However, the microstructure of a ceramic has a great influence on its compressive strength and on its ballistic efficiency. To study the influence of microstructural parameters on the dynamic compressive behaviour of silicon carbides, isentropic compression experiments have been performed on two silicon carbide grades using a high pulsed power generator called GEPI. Contrary to plate impact experiments, the use of the GEPI device and of the lagrangian analysis allows determining the whole loading path. The two SiC grades studied present different Hugoniot elastic limit (HEL due to their different microstructures. For these materials, the experimental technique allowed evaluating the evolution of the equivalent stress during the dynamic compression. It has been observed that these two grades present a work hardening more or less pronounced after the HEL. The densification of the material seems to have more influence on the HEL than the grain size.

  12. Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam

    CERN Document Server

    Roy, Prabir K; Baca, David; Bieniosek, Frank; Coleman, Joshua E; Davidson, Ronald C; Efthimion, Philip; Eylon, Shmuel; Gilson, Erik P; Grant Logan, B; Greenway, Wayne; Henestroza, Enrique; Kaganovich, Igor D; Leitner, Matthaeus; Rose, David; Sefkow, Adam; Sharp, William M; Shuman, Derek; Thoma, Carsten H; Vanecek, David; Waldron, William; Welch, Dale; Yu, Simon

    2005-01-01

    Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first compression experiment, a 260 KeV, 25 mA, K+ ion beam of centimeters size is radially compressed to a mm size spot by neutralization in a meter-long plasma column and beam peak current is longitudinally compressed by an induction velocity tilt core. Instrumentation, preliminary results of the experiments, and practical limits of compression are presented. These include parameters such as emittance, degree of neutralization, velocity tilt time profile, and accuracy of measurements (fast and spatially high resolution diagnostic) are discussed.

  13. Direct-drive laser-fusion in the US

    International Nuclear Information System (INIS)

    McCrory, R.L.; Soures, J.M.; Audebert, P.

    1986-01-01

    Direct-drive experiments at the University of Rochester's Laboratory for Laser Energetics (LLE) and the Naval Research Laboratory (NRL) are presently addressing issues in pellet compression and heating: efficiency of coupling of laser energy to the target and the coupling of absorbed energy to the fuel, drive uniformity, hydrodynamic stability, preheat arising from laser plasma instabilities and x-rays, and target diagnostics. The 24-beam, 2500-Joule, 351 nm OMEGA laser system at LLE has been used in an experimental effort to achieve high compressed DT fuel densities. Detailed hydrodynamic computer simulations at NRL predict that the growth rate of the ablative Rayleigh-Taylor instability is less than the classical values. Recent Rayleigh-Taylor experiments ar NRL are testing these predictions

  14. Plasma physics study and laser development for the fast ignition realization experiment (FIREX) project

    International Nuclear Information System (INIS)

    Azechi, H.; Mima, K.; Fujimoto, Y.

    2008-10-01

    Since the approval of the first phase of Fast Ignition Realization Experiment (FIREX-I), we have devoted our efforts on designing advanced targets and constructing the world highest-energy Peta Watt laser. The new target design has the following features. The coupling efficiency from the heating laser to the thermal energy of the compressed core plasma can be increased by the two ways:1) Low-Z foam layer on the inner surface of the cone for optimum absorption. 2) Double cone. Electrons generated in the inner surface of the double cone will return by sheathe potential generated between two cones. The implosion performance can be improved by three ways: 3) Low-Z plastic layer on the outer surface of the cone may suppress the expansion of the Au cone that flows into the interior of the compressed core. 4) Br doped plastic ablator may significantly moderate the Rayleigh-Taylor instability, making implosion more stable. 5) Evacuation of the target center to prevent gas jets from destroying the cone tip. For project robustness, we also explore 6) impact ignition scheme that eliminates complexity of laser-plasma interaction while keeping the compactness advantage of fast ignition. The fully integrated fast ignition experiment is scheduled on 2009. If subsequent FIREX-II will start as proposed, the ignition and burn will be demonstrated shortly after the ignition at NIF and LMJ, providing a scientific database of both central and fast ignition. (author)

  15. Thermonuclear fusion plasma produced by lasers

    International Nuclear Information System (INIS)

    Yamanaka, C.; Yokoyama, M.; Nakai, S.; Sasaki, T.; Yoshida, K.; Matoba, M.; Yamabe, C.; Tschudi, T.; Yamanaka, T.; Mizui, J.; Yamaguchi, N.; Nishikawa, K.

    1975-01-01

    Recently, much attention has been focused on laser fusion schemes using high-density plasmas produced by implosion. Scientific-feasibility laser-fusion experiments are now in time. But the physics of interaction between laser and plasma, the high-compression technique and the development of high-power lasers are still important problems to be solved if laser fusion is to make some progress. In the field of laser-plasma coupling, experiments were carried out in which hydrogen and deuterium sticks were bombarded by laser beams; in these experiments, a glass-laser system, LETKKO-I, with an energy of 50 J in a nanosecond pulse, and a double-discharge TEA CO 2 laser system with an energy of 100 J in a 100-ns pulse were used. A decrease in reflectivity occurred at a laser intensity one order of magnitude higher than the parametric-instability threshold. Self-phase modulation of scattered light due to modulational instability was found. A Brillouin-backscattering isotope effect due to the hydrogen and deuterium plasma has also been observed in the red-side part of the SHG-light. Preliminary compression experiments have been carried out using a glass-laser system LETKKO-II, with an energy of 250-1000 J in a ns-pulse. A hologram has been used to study shock waves in the plasma due to the SHG-light converted from the main laser beam. Development of high-power lasers has been promoted, such as disc-glass lasers, E-beam CO 2 lasers and excimer lasers. (author)

  16. Theoretical models for describing longitudinal bunch compression in the neutralized drift compression experiment

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2006-09-01

    Full Text Available Heavy ion drivers for warm dense matter and heavy ion fusion applications use intense charge bunches which must undergo transverse and longitudinal compression in order to meet the requisite high current densities and short pulse durations desired at the target. The neutralized drift compression experiment (NDCX at the Lawrence Berkeley National Laboratory is used to study the longitudinal neutralized drift compression of a space-charge-dominated ion beam, which occurs due to an imposed longitudinal velocity tilt and subsequent neutralization of the beam’s space charge by background plasma. Reduced theoretical models have been used in order to describe the realistic propagation of an intense charge bunch through the NDCX device. A warm-fluid model is presented as a tractable computational tool for investigating the nonideal effects associated with the experimental acceleration gap geometry and voltage waveform of the induction module, which acts as a means to pulse shape both the velocity and line density profiles. Self-similar drift compression solutions can be realized in order to transversely focus the entire charge bunch to the same focal plane in upcoming simultaneous transverse and longitudinal focusing experiments. A kinetic formalism based on the Vlasov equation has been employed in order to show that the peaks in the experimental current profiles are a result of the fact that only the central portion of the beam contributes effectively to the main compressed pulse. Significant portions of the charge bunch reside in the nonlinearly compressing part of the ion beam because of deviations between the experimental and ideal velocity tilts. Those regions form a pedestal of current around the central peak, thereby decreasing the amount of achievable longitudinal compression and increasing the pulse durations achieved at the focal plane. A hybrid fluid-Vlasov model which retains the advantages of both the fluid and kinetic approaches has been

  17. Results of subscale MTF compression experiments

    Science.gov (United States)

    Howard, Stephen; Mossman, A.; Donaldson, M.; Fusion Team, General

    2016-10-01

    In magnetized target fusion (MTF) a magnetized plasma torus is compressed in a time shorter than its own energy confinement time, thereby heating to fusion conditions. Understanding plasma behavior and scaling laws is needed to advance toward a reactor-scale demonstration. General Fusion is conducting a sequence of subscale experiments of compact toroid (CT) plasmas being compressed by chemically driven implosion of an aluminum liner, providing data on several key questions. CT plasmas are formed by a coaxial Marshall gun, with magnetic fields supported by internal plasma currents and eddy currents in the wall. Configurations that have been compressed so far include decaying and sustained spheromaks and an ST that is formed into a pre-existing toroidal field. Diagnostics measure B, ne, visible and x-ray emission, Ti and Te. Before compression the CT has an energy of 10kJ magnetic, 1 kJ thermal, with Te of 100 - 200 eV, ne 5x1020 m-3. Plasma was stable during a compression factor R0/R >3 on best shots. A reactor scale demonstration would require 10x higher initial B and ne but similar Te. Liner improvements have minimized ripple, tearing and ejection of micro-debris. Plasma facing surfaces have included plasma-sprayed tungsten, bare Cu and Al, and gettering with Ti and Li.

  18. On the failure of NiAl bicrystals during laser-induced shock compression

    International Nuclear Information System (INIS)

    Loomis, Eric; Swift, Damian; Peralta, Pedro; McClellan, Ken

    2005-01-01

    Thin NiAl bicrystals 5 mm in diameter and 150-350 μm thick were tested under laser-induced shock compression to evaluate the material behavior and the effect of localized strain at the grain boundary on the failure of these specimens. Circular NiAl bicrystal samples with random misorientation were grown using a modified Czochralski technique and samples were prepared for shock compression at moderate pressures (<10 GPa). The observed crack patterns on the drive surface as well as the free surface were examined using optical microscopy. Transmission electron microscopy (TEM) of the drive surface as well as in the bulk of one grain was performed on recovered specimens following shock compression. This revealed that a nanocrystalline region with a grain size of 15-20 nm formed on a thin layer at the drive surface following the plasma expansion phase of the laser-induced shock. TEM in the bulk of one grain showed that plastic deformation occurred in a periodic fashion through propagation of dislocation clusters. Cracking on the free surface of the samples revealed a clear grain boundary affected zone (GBAZ) due to scattering of the shock wave and variations in wave speed across the inclined boundary. Damage tended to accumulate in the grain into which the elastic wave refracted. This damage accumulation corresponds well to the regions in which the transmitted waves impinged on the free surface as predicted by elastic scattering models

  19. Theory of high density laser fusion

    International Nuclear Information System (INIS)

    Zimmerman, G.B.; Nuckolls, J.H.

    1975-01-01

    A basic laser fusion scheme is presented. Some of its subtleties are described and the theoretical difficulties which now appear to be the major obstacles are considered. Interpretations of some recent laser compression experiments are given. (U.S.)

  20. Image compression of bone images

    International Nuclear Information System (INIS)

    Hayrapetian, A.; Kangarloo, H.; Chan, K.K.; Ho, B.; Huang, H.K.

    1989-01-01

    This paper reports a receiver operating characteristic (ROC) experiment conducted to compare the diagnostic performance of a compressed bone image with the original. The compression was done on custom hardware that implements an algorithm based on full-frame cosine transform. The compression ratio in this study is approximately 10:1, which was decided after a pilot experiment. The image set consisted of 45 hand images, including normal images and images containing osteomalacia and osteitis fibrosa. Each image was digitized with a laser film scanner to 2,048 x 2,048 x 8 bits. Six observers, all board-certified radiologists, participated in the experiment. For each ROC session, an independent ROC curve was constructed and the area under that curve calculated. The image set was randomized for each session, as was the order for viewing the original and reconstructed images. Analysis of variance was used to analyze the data and derive statistically significant results. The preliminary results indicate that the diagnostic quality of the reconstructed image is comparable to that of the original image

  1. Plasma crowbars in cylindrical flux compression experiments

    International Nuclear Information System (INIS)

    Suter, L.J.

    1979-01-01

    We have done a series of one- and two-dimensional calculations of hard-core Z-pinch flux compression experiments in order to study the effect of a plasma on these systems. These calculations show that including a plasma can reduce the amount of flux lost during the compression. Flux losses to the outer wall of such experiments can be greatly reduced by a plasma conducting sheath which forms along the wall. This conducting sheath consists of a cold, dense high β, unmagnetized plasma which has enough pressure to balance a large field gradient. Flux which is lost into the center conductor is not effectively stopped by this plasma sheath until late in the implosion, at which time a layer similar to the one formed at the outer wall is created. Two-dimensionl simulations show that flux losses due to arching along the sliding contact of the experiment can be effectively stopped by the formation of a plasma conducting sheath

  2. High power, short pulses ultraviolet laser for the development of a new x-ray laser

    International Nuclear Information System (INIS)

    Meixler, L.; Nam, C.H.; Robinson, J.; Tighe, W.; Krushelnick, K.; Suckewer, S.; Goldhar, J.; Seely, J.; Feldman, U.

    1989-04-01

    A high power, short pulse ultraviolet laser system (Powerful Picosecond-Laser) has been developed at the Princeton Plasma Physics Laboratory (PPPL) as part of experiments designed to generate shorter wavelength x-ray lasers. With the addition of pulse compression and a final KrF amplifier the laser output is expected to have reached 1/3-1/2 TW (10 12 watts) levels. The laser system, particularly the final amplifier, is described along with some initial soft x-ray spectra from laser-target experiments. The front end of the PP-Laser provides an output of 20--30 GW (10 9 watts) and can be focussed to intensities of /approximately/10 16 W/cm 2 . Experiments using this output to examine the effects of a prepulse on laser-target interaction are described. 19 refs., 14 figs

  3. New experimental platform to study high density laser-compressed matter

    International Nuclear Information System (INIS)

    Gauthier, M.; Fletcher, L. B.; Galtier, E.; Gamboa, E. J.; Granados, E.; Hastings, J. B.; Heimann, P.; Lee, H. J.; Nagler, B.; Schropp, A.; Falcone, R.; Glenzer, S. H.; Ravasio, A.; Gleason, A.; Döppner, T.; LePape, S.; Ma, T.; Pak, A.; MacDonald, M. J.; Ali, S.

    2014-01-01

    We have developed a new experimental platform at the Linac Coherent Light Source (LCLS) which combines simultaneous angularly and spectrally resolved x-ray scattering measurements. This technique offers a new insights on the structural and thermodynamic properties of warm dense matter. The < 50 fs temporal duration of the x-ray pulse provides near instantaneous snapshots of the dynamics of the compression. We present a proof of principle experiment for this platform to characterize a shock-compressed plastic foil. We observe the disappearance of the plastic semi-crystal structure and the formation of a compressed liquid ion-ion correlation peak. The plasma parameters of shock-compressed plastic can be measured as well, but requires an averaging over a few tens of shots

  4. Solid - solid and solid - liquid phase transitions of iron and iron alloys under laser shock compression

    Science.gov (United States)

    Harmand, M.; Krygier, A.; Appel, K.; Galtier, E.; Hartley, N.; Konopkova, Z.; Lee, H. J.; McBride, E. E.; Miyanishi, K.; Nagler, B.; Nemausat, R.; Vinci, T.; Zhu, D.; Ozaki, N.; Fiquet, G.

    2017-12-01

    An accurate knowledge of the properties of iron and iron alloys at high pressures and temperatures is crucial for understanding and modelling planetary interiors. While Earth-size and Super-Earth Exoplanets are being discovered in increasingly large numbers, access to detailed information on liquid properties, melting curves and even solid phases of iron and iron at the pressures and temperatures of their interiors is still strongly limited. In this context, XFEL sources coupled with high-energy lasers afford unique opportunities to measure microscopic structural properties at far extreme conditions. Also the achievable time resolution allows the shock history and phase transition mechanisms to be followed during laser compression, improving our understanding of the high pressure and high strain experiments. Here we present recent studies devoted to investigate the solid-solid and solid-liquid transition in laser-shocked iron and iron alloys (Fe-Si, Fe-C and Fe-O alloys) using X-ray diffraction and X-ray diffuse scattering. Experiment were performed at the MEC end-station of the LCLS facility at SLAC (USA). Detection of the diffuse scattering allowed the identification of the first liquid peak position along the Hugoniot, up to 4 Mbar. The time resolution shows ultrafast (between several tens and several hundreds of picoseconds) solid-solid and solid-liquid phase transitions. Future developments at XFEL facilities will enable detailed studies of the solid and liquid structures of iron and iron alloys as well as out-of-Hugoniot studies.

  5. The FRX-C/LSM compression experiment

    International Nuclear Information System (INIS)

    Rej, D.J.; Siemon, R.E.; Taggart, D.P.

    1989-01-01

    After two years of preparation, hardware for high-power FRC compression heating studies is now being installed onto FRX-C/LSM. FRCs will be formed and translated out of the θ-pinch source, and into a compressor where the external B-field will be increased from 0.4 to 2 T in 55 μs. The compressed FRC can then be translated into a third stage for further study. A principal experimental goal is to study FRC confinement at the high energy density, n(T/sub e/ + T/sub i/) ≤ 1.0 /times/ 10 22 keV/m 3 , associated with the large external field. Experiments are scheduled to begin in April. 11 refs., 5 figs

  6. Temperature measurement in a compressible flow field using laser-induced iodine fluorescence

    Science.gov (United States)

    Fletcher, D. G.; Mcdaniel, J. C.

    1987-01-01

    The thermometric capability of a two-line fluorescence technique using iodine seed molecules in air is investigated analytically and verified experimentally in a known steady compressible flow field. Temperatures ranging from 165 to 295 K were measured in the flowfield using two iodine transitions accessed with a 30-GHz dye-laser scan near 543 nm. The effect of pressure broadening on temperature measurement is evaluated.

  7. A proposed laser wakefield acceleration experiment

    International Nuclear Information System (INIS)

    Ebrahim, N.A.

    1995-05-01

    In this report we discuss the basic concepts of a laser wakefield experiment using an ultrashort laser pulse. In particular, we obtain some heuristic estimates of experimental parameters relevant to an experiment to test the laser wakefield acceleration concept. (author). 8 refs., 2 tabs

  8. Recent laser experiments on the Aurora KrF/ICF laser system

    International Nuclear Information System (INIS)

    Turner, T.P.; Jones, J.E.; Czuchlewski, S.J.; Watt, R.G.; Thomas, S.J.; Kang, M.; Tallman, C.R.; Mack, J.M.; Figueira, J.F.

    1990-01-01

    The Aurora KrF/ICF Laser Facility at Los Alamos is operational at the kilojoule-level for both laser and target experiments. We report on recent laser experiments on the system and resulting system improvements. 3 refs., 4 figs

  9. High-speed photographic methods for compression dynamics investigation of laser irradiated shell target

    International Nuclear Information System (INIS)

    Basov, N.G.; Kologrivov, A.A.; Krokhin, O.N.; Rupasov, A.A.; Shikanov, A.S.

    1979-01-01

    Three methods are described for a high-speed diagnostics of compression dynamics of shell targets being spherically laser-heated on the installation ''Kal'mar''. The first method is based on the direct investigation of the space-time evolution of the critical-density region for Nd-laser emission (N sub(e) asymptotically equals 10 21 I/cm 3 ) by means of the streak photography of plasma image in the second-harmonic light. The second method involves investigation of time evolution of the second-harmonic spectral distribution by means of a spectrograph coupled with a streak camera. The use of a special laser pulse with two time-distributed intensity maxima for the irradiation of shell targets, and the analysis of the obtained X-ray pin-hole pictures constitute the basis of the third method. (author)

  10. High level compressive residual stresses produced in aluminum alloys by laser shock processing

    International Nuclear Information System (INIS)

    Gomez-Rosas, G.; Rubio-Gonzalez, C.; Ocana, J.L; Molpeceres, C.; Porro, J.A.; Chi-Moreno, W.; Morales, M.

    2005-01-01

    Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm 2 in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm. Results using pulse densities of 2500 pulses/cm 2 in 6061-T6 aluminum samples and 5000 pulses/cm 2 in 2024 aluminum samples are presented. High level of compressive residual stresses are produced -1600 MPa for 6061-T6 Al alloy, and -1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products

  11. The laser thermonuclear fusion

    International Nuclear Information System (INIS)

    Coutant, J.; Dautray, R.; Decroisette, M.; Watteau, J.P.

    1987-01-01

    Principle of the thermonuclear fusion by inertial confinement: required characteristics of the deuterium-tritium plasma and of the high power lasers to be used Development of high power lasers: active media used; amplifiers; frequency conversion; beam quality; pulse conditioning; existing large systems. The laser-matter interaction: collision and collective interaction of the laser radiation with matter; transport of the absorbed energy; heating and compression of deuterium-tritium; diagnoses and their comparison with the numerical simulation of the experiment; performances. Conclusions: difficulties to overcome; megajoule lasers; other energy source: particles beams [fr

  12. Laser experiments for chemistry and physics

    CERN Document Server

    Compton, Robert N

    2016-01-01

    Lasers are employed throughout science and technology, in fundamental research, the remote sensing of atmospheric gases or pollutants, communications, medical diagnostics and therapies, and the manufacturing of microelectronic devices. Understanding the principles of their operation, which underlie all of these areas, is essential for a modern scientific education. This text introduces the characteristics and operation of lasers through laboratory experiments designed for the undergraduate curricula in chemistry and physics. Introductory chapters describe the properties of light, the history of laser invention, the atomic, molecular, and optical principles behind how lasers work, and the kinds of lasers available today. Other chapters include the basic theory of spectroscopy and computational chemistry used to interpret laser experiments. Experiments range from simple in-class demonstrations to more elaborate configurations for advanced students. Each chapter has historical and theoretical background, as well...

  13. NTES laser facility for physics experiments

    International Nuclear Information System (INIS)

    Christie, D.J.; Foley, R.J.; Frank, D.N.

    1989-01-01

    This paper discusses the following topics on the NTES laser facility: Mission Statement and Project Description; Experiment Area; High-Energy, Double-Pass Laser; Facilities; Laser Control and Data Acquisition; and Auxiliary Lasers

  14. Magnetic Compression Experiment at General Fusion with Simulation Results

    Science.gov (United States)

    Dunlea, Carl; Khalzov, Ivan; Hirose, Akira; Xiao, Chijin; Fusion Team, General

    2017-10-01

    The magnetic compression experiment at GF was a repetitive non-destructive test to study plasma physics applicable to Magnetic Target Fusion compression. A spheromak compact torus (CT) is formed with a co-axial gun into a containment region with an hour-glass shaped inner flux conserver, and an insulating outer wall. External coil currents keep the CT off the outer wall (levitation) and then rapidly compress it inwards. The optimal external coil configuration greatly improved both the levitated CT lifetime and the rate of shots with good compressional flux conservation. As confirmed by spectrometer data, the improved levitation field profile reduced plasma impurity levels by suppressing the interaction between plasma and the insulating outer wall during the formation process. We developed an energy and toroidal flux conserving finite element axisymmetric MHD code to study CT formation and compression. The Braginskii MHD equations with anisotropic heat conduction were implemented. To simulate plasma / insulating wall interaction, we couple the vacuum field solution in the insulating region to the full MHD solution in the remainder of the domain. We see good agreement between simulation and experiment results. Partly funded by NSERC and MITACS Accelerate.

  15. Experimental study of laser-plasma interaction physics with short laser wavelength

    International Nuclear Information System (INIS)

    Labaune, C.; Amiranoff, F.; Fabre, E.; Matthieussent, G.; Rousseaux, C.; Baton, S.

    1989-01-01

    Many non-linear processes can affect laser-plasma coupling in fusion experiments. The interaction processes of interest involve three or more waves, including the incident electromagnetic wave and various selections of electromagnetic, electrostatic and accoustic waves. Whenever plasma waves are involved (stimulated Raman scattering, two-plasmon decay instability, parametric decay instability and others), energetic electrons are created through the various damping processes of these waves: these energetic electrons in turn deleteriously affect the compression phase in laser fusion experiments through pre-heating of the fuel core. Some parametric processes lead primarily to loss of incident laser energy (stimulated Brillouin scattering) while others, such as filamentation, lead to strongly enhanced local laser intensities through the focusing of part (or all) of the laser beam into filaments of very small dimensions with a concomitant expulsion of the plasma out of these regions. So filamentation destroys the uniformity of energy deposition in the plasma and prevents high compression efficiency of the target. These interaction effects are typically of parametric nature, with their thresholds and growth rates depending critically on plasma scale lengths. Since these scale lengths increase with available laser energy and since millimeter sized plasmas are expected from reactor targets which will be used in direct drive implosion experiments, a good understanding of these processes and their saturation mechanisms becomes imperative. We report here the results on absolute energy measurements and time-resolved spectra of SRS and SBS obtained in various types of plasmas where the major changes were the inhomogeneity scale lengths. (author) 7 refs., 7 figs

  16. Trends in laser-plasma-instability experiments for laser fusion

    International Nuclear Information System (INIS)

    Drake, R.P.

    1991-01-01

    Laser-plasma instability experiments for laser fusion have followed three developments. These are advances in the technology and design of experiments, advances in diagnostics, and evolution of the design of high-gain targets. This paper traces the history of these three topics and discusses their present state. Today one is substantially able to produce controlled plasma conditions and to diagnose specific instabilities within such plasmas. Experiments today address issues that will matter for future laser facilities. Such facilities will irradiate targets with ∼1 MJ of visible or UV light pulses that are tens of nanoseconds in duration, very likely with a high degree of spatial and temporal incoherence. 58 refs., 4 figs

  17. A Space-Frequency Data Compression Method for Spatially Dense Laser Doppler Vibrometer Measurements

    Directory of Open Access Journals (Sweden)

    José Roberto de França Arruda

    1996-01-01

    Full Text Available When spatially dense mobility shapes are measured with scanning laser Doppler vibrometers, it is often impractical to use phase-separation modal parameter estimation methods due to the excessive number of highly coupled modes and to the prohibitive computational cost of processing huge amounts of data. To deal with this problem, a data compression method using Chebychev polynomial approximation in the frequency domain and two-dimensional discrete Fourier series approximation in the spatial domain, is proposed in this article. The proposed space-frequency regressive approach was implemented and verified using a numerical simulation of a free-free-free-free suspended rectangular aluminum plate. To make the simulation more realistic, the mobility shapes were synthesized by modal superposition using mode shapes obtained experimentally with a scanning laser Doppler vibrometer. A reduced and smoothed model, which takes advantage of the sinusoidal spatial pattern of structural mobility shapes and the polynomial frequency-domain pattern of the mobility shapes, is obtained. From the reduced model, smoothed curves with any desired frequency and spatial resolution can he produced whenever necessary. The procedure can he used either to generate nonmodal models or to compress the measured data prior to modal parameter extraction.

  18. Plans for longitudinal and transverse neutralized beam compression experiments, and initial results from solenoid transport experiments

    International Nuclear Information System (INIS)

    Seidl, P.A.; Armijo, J.; Baca, D.; Bieniosek, F.M.; Coleman, J.; Davidson, R.C.; Efthimion, P.C.; Friedman, A.; Gilson, E.P.; Grote, D.; Haber, I.; Henestroza, E.; Kaganovich, I.; Leitner, M.; Logan, B.G.; Molvik, A.W.; Rose, D.V.; Roy, P.K.; Sefkow, A.B.; Sharp, W.M.; Vay, J.L.; Waldron, W.L.; Welch, D.R.; Yu, S.S.

    2007-01-01

    This paper presents plans for neutralized drift compression experiments, precursors to future target heating experiments. The target-physics objective is to study warm dense matter (WDM) using short-duration (∼1 ns) ion beams that enter the targets at energies just above that at which dE/dx is maximal. High intensity on target is to be achieved by a combination of longitudinal compression and transverse focusing. This work will build upon recent success in longitudinal compression, where the ion beam was compressed lengthwise by a factor of more than 50 by first applying a linear head-to-tail velocity tilt to the beam, and then allowing the beam to drift through a dense, neutralizing background plasma. Studies on a novel pulse line ion accelerator were also carried out. It is planned to demonstrate simultaneous transverse focusing and longitudinal compression in a series of future experiments, thereby achieving conditions suitable for future WDM target experiments. Future experiments may use solenoids for transverse focusing of un-neutralized ion beams during acceleration. Recent results are reported in the transport of a high-perveance heavy ion beam in a solenoid transport channel. The principal objectives of this solenoid transport experiment are to match and transport a space-charge-dominated ion beam, and to study associated electron-cloud and gas effects that may limit the beam quality in a solenoid transport system. Ideally, the beam will establish a Brillouin-flow condition (rotation at one-half the cyclotron frequency). Other mechanisms that potentially degrade beam quality are being studied, such as focusing-field aberrations, beam halo, and separation of lattice focusing elements

  19. The VELOCE pulsed power generator for isentropic compression experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Tommy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Asay, James Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Chantrenne, Sophie J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hickman, Randall John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Willis, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Shay, Andrew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Grine-Jones, Suzi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hall, Clint Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Baer, Melvin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center

    2007-12-01

    Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic (MHD) simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.

  20. Characterization of silicon microstrip sensors with a pulsed infrared laser system for the CBM experiment at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Pradeep [Goethe Univ., Frankfurt (Germany); GSI (Germany); Eschke, Juergen [GSI (Germany); FAIR (Germany); Collaboration: CBM-Collaboration

    2014-07-01

    The Silicon Tracking System (STS) for the Compressed Baryonic Matter (CBM) experiment at FAIR will comprise more than 1200 double-sided silicon microstrip sensors. For the quality assurance of the prototype sensors a laser test system has been built up. The aim of the sensor scans with the pulsed infrared laser system is to determine the charge sharing between strips and to measure the uniformity of the sensor response over the whole active area. The laser system measures the sensor response in an automatized procedure at several thousand positions across the sensor with focused infrared laser light (σ∼15 μm, λ=1060 nm). The duration (5 ns) and power (few mW) of the laser pulses are selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24k electrons, which is similar to the charge created by minimum ionizing particles in these sensors. Results from the characterization of monolithic active pixel sensors, to understand the spot-size of the laser, and laser scans for different sensors are presented.

  1. Free-beam soliton self-compression in air

    Science.gov (United States)

    Voronin, A. A.; Mitrofanov, A. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Pugžlys, A.; Panchenko, V. Ya; Shumakova, V.; Ališauskas, S.; Baltuška, A.; Zheltikov, A. M.

    2018-02-01

    We identify a physical scenario whereby soliton transients generated in freely propagating laser beams within the regions of anomalous dispersion in air can be compressed as a part of their free-beam spatiotemporal evolution to yield few-cycle mid- and long-wavelength-infrared field waveforms, whose peak power is substantially higher than the peak power of the input pulses. We show that this free-beam soliton self-compression scenario does not require ionization or laser-induced filamentation, enabling high-throughput self-compression of mid- and long-wavelength-infrared laser pulses within a broad range of peak powers from tens of gigawatts up to the terawatt level. We also demonstrate that this method of pulse compression can be extended to long-range propagation, providing self-compression of high-peak-power laser pulses in atmospheric air within propagation ranges as long as hundreds of meters, suggesting new ways towards longer-range standoff detection and remote sensing.

  2. Experiments with polymer coated microspheres irradiated by the Shiva laser system

    International Nuclear Information System (INIS)

    Auerbach, J.M.; Manes, K.R.; Matthews, D.L.

    1979-01-01

    Polymer coated spherical targets have been irradiated by the Shiva laser system in an effort to compress the contained 10 mg/cc DT fuel to super liquid densities. Glass microspheres of 140 μm ID and 5 μm wall thickness with polymer coatings 15 μm to 100 μm thick have been irradiated with laser pulses of 4 kilojoules in 200 psec FWHM. Target performance was diagnosed with neutron yield measurements, radiochemistry, Argon line imaging, and x-ray imaging techniques. Ball in plate targets achieved greater implosion symmetry than free-standing ball targets. With yields of 10 7 to 10 8 neutrons, targets reached DT fuel compressions of several times liquid density

  3. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  4. X-ray diagnostics in the laser-initiated fusion program

    International Nuclear Information System (INIS)

    Godwin, R.P.

    1975-08-01

    The high-density and high-temperature plasma conditions required for successful laser-initiated fusion make x-ray diagnostics a valuable tool in this exciting field. Measurements of the hard x-ray continuum emitted from laser targets provide insight into the complex laser-plasma coupling physics and the consequent energy transport through the bremsstrahlung signature of energetic electrons. X-ray techniques are important in the selection and assay of microballoon targets for current compression experiments. X-ray imaging experiments and diffraction spectroscopy of highly stripped atoms can provide information upon the symmetry, density and temperature of laser targets. Extremely high temporal and spatial resolution may be required for definitive diagnostic information on compressed targets. While laser-produced plasmas are interesting as possible intense x-ray sources and as a possible means of achieving x-ray lasing, those topics are outside the scope of this review. (auth)

  5. Intensification of rare gas halide lasers with application to laser fusion

    International Nuclear Information System (INIS)

    Jacobs, R.R.; Eimerl, D.; Goldhar, J.; Murray, J.R.; Rapoport, W.R.; Schlitt, L.; Swingle, J.C.

    1980-01-01

    The two techniques of backward-wave Raman pulse compression and pulse stacking are reviewed in the context of using KrF lasers as drivers in inertial confinement fusion. Experimental and theoretical results on Raman pulse compression in methane are presented including data on 70 to 75% pump energy extraction by the counter propagating Stokes wave. Results from on-going pulse stacker/Raman compressor experiments are also described, along with future investigations in this general area

  6. X-ray laser '' oscillator-amplifier'' experiments

    International Nuclear Information System (INIS)

    Shimkaveg, G.M.; Carter, M.R.; Young, B.K.F.; Walling, R.S.; Osterheld, A.L.; Trebes, J.E.; London, R.A.; Ratowsky, R.P.; Stewart, R.E.; Craxton, R.S.

    1993-01-01

    We present results from experiments directed toward increasing the degree of transverse coherence in x-ray laser beams. We have concentrated on the neon-like yttrium (Z=39) collisionally-pumped x-ray laser as the test system for these studies because of its unique combination of brightness, monochromaticity, and high-reflectivity optics availability. Attempts at improving laser performance using proximate feedback optics failed. Modest success has been found to date in ''double foil'' experiments, involving two x-ray lasers spatially separated by 29 cm and shot sequentially in an ''oscillator-amplifier'' configuration

  7. Image compression software for the SOHO LASCO and EIT experiments

    Science.gov (United States)

    Grunes, Mitchell R.; Howard, Russell A.; Hoppel, Karl; Mango, Stephen A.; Wang, Dennis

    1994-01-01

    This paper describes the lossless and lossy image compression algorithms to be used on board the Solar Heliospheric Observatory (SOHO) in conjunction with the Large Angle Spectrometric Coronograph and Extreme Ultraviolet Imaging Telescope experiments. It also shows preliminary results obtained using similar prior imagery and discusses the lossy compression artifacts which will result. This paper is in part intended for the use of SOHO investigators who need to understand the results of SOHO compression in order to better allocate the transmission bits which they have been allocated.

  8. Commissioning Results of the Upgraded Neutralized Drift Compression Experiment

    International Nuclear Information System (INIS)

    Lidia, S.M.; Roy, P.K.; Seidl, P.A.; Waldron, W.L.; Gilson, E.P.

    2009-01-01

    Recent changes to the NDCX beamline offer the promise of higher charge compressed bunches (>15nC), with correspondingly large intensities (>500kW/cm 2 ), delivered to the target plane for ion-beam driven warm dense matter experiments. We report on commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.

  9. Compression Stockings after Endovenous Laser Ablation of the Great Saphenous Vein : A Prospective Randomized Controlled Trial

    NARCIS (Netherlands)

    Bakker, N. A.; Schieven, L. W.; Bruins, R. M. G.; van den Berg, M.; Hissink, R. J.

    2013-01-01

    Objectives: To determine if the duration of wearing compression stockings after endovenous laser ablation (EVLA) of the great saphenous vein (GSV) has influence on pain and quality of life. Methods: This was a prospective randomized controlled trial. Between December 2006 and February 2008, 109

  10. Drift compression experiments on MBE-4 and related emittance growth phenomena

    International Nuclear Information System (INIS)

    Eylon, S.; Faltens, A.; Fawley, W.; Garvey, T.; Hahn, K.; Henestroza, E.; Smith, L.

    1991-04-01

    We have recently conducted a series of experiments on the MBE-4 heavy ion accelerator in which a velocity tilt was placed on the beam in the first accelerating section beyond the injector, followed by drift compression over the remaining 11 meters. Depending upon the magnitude of the velocity tilt and the accompanying mismatch in the focusing lattice, emittance growth was observed, manifested by ''butterfly'' shapes in x - x' phase space. We discuss various analytical limits on ion beam compression and relate them to these experiments and also to a driver for a heavy ion fusion reactor. We also present numerical simulations which investigate various aspects of compression and consequent emittance growth. 2 refs., 3 figs., 1 tab

  11. Simulations and experiments of intense ion beam compression in space and time

    International Nuclear Information System (INIS)

    Yu, S.S.; Seidl, P.A.; Roy, P.K.; Lidia, S.M.; Coleman, J.E.; Kaganovich, I.D.; Gilson, E.P.; Welch, Dale Robert; Sefkow, Adam B.; Davidson, R.C.

    2008-01-01

    The Heavy Ion Fusion Science Virtual National Laboratory has achieved 60-fold longitudinal pulse compression of ion beams on the Neutralized Drift Compression Experiment (NDCX) (P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005)). To focus a space-charge-dominated charge bunch to sufficiently high intensities for ion-beam-heated warm dense matter and inertial fusion energy studies, simultaneous transverse and longitudinal compression to a coincident focal plane is required. Optimizing the compression under the appropriate constraints can deliver higher intensity per unit length of accelerator to the target, thereby facilitating the creation of more compact and cost-effective ion beam drivers. The experiments utilized a drift region filled with high-density plasma in order to neutralize the space charge and current of an ∼300 keV K + beam and have separately achieved transverse and longitudinal focusing to a radius Z 2 MeV) ion beam user-facility for warm dense matter and inertial fusion energy-relevant target physics experiments.

  12. Laser fusion experiments at 2 TW

    International Nuclear Information System (INIS)

    Storm, E.K.; Ahlstrom, H.G.; Boyle, M.J.

    1976-01-01

    The Lawrence Livermore Laboratory Solid State Laser System, Argus, has successfully performed laser implosion experiments at power levels exceeding 2 TW. D-T filled glass microspheres have been imploded to yield thermonuclear reaction products in excess of 5 x 10 8 per event. Neutron and α time-of-flight measurements indicate that D-T ion temperatures of approximately 5 to 6 keV and a density confinement time product (n tau) of approximately 1 x 10 12 were obtained in these experiments. Typically two 40J, 40 psec pulses of 1.06 μm light were focused on targets using 20 cm aperture f/l lenses, producing intensities at the target in excess of 10 16 W/cm 2 . An extensive array of diagnostics routinely monitored the laser performance and the laser target interaction process. Measurements of absorption and asymmetry in both the scattered light distribution and the ion blow off is evidence for non-classical absorption mechanisms and density scale heights of the order of 2 μm or less. The symmetry of the thermonuclear burn region is investigated by monitoring the α-particle flux in several directions, and an experiment to image the thermonuclear burn region is in process. These experiments significantly extend our data base and our understanding of laser induced thermonuclear implosions and the basic laser plasma interaction physics from the 0.4 to 0.7 TW level of previous experiments

  13. Laser fusion experiments at 2 TW

    International Nuclear Information System (INIS)

    Storm, E.K.; Ahlstrom, H.G.; Boyle, M.J.

    1976-01-01

    The Lawrence Livermore Laboratory Solid State Laser System, Arqus, has successfully performed laser implosion experiments at power levels exceeding 2 TW. D-T filled glass microspheres have been imploded to yield thermonuclear reaction products in excess of 5 x 10 8 per event. Neutron and α time-of-flight measurements indicate that D-T ion temperatures of approximately 5-6 keV and a density confinement time product (n tau) of approximately 1 x 10 12 were obtained in these experiments. Typically two 40J, 40 psec pulses of 1.06 μm light were focused on targets using 20 cm aperture f/1 lenses, producing intensities at the target in excess of 10 16 W/cm 2 . An extensive array of diagnostics routinely monitored the laser performance and the laser target interaction process. Measurements of absorption and asymmetry in both the scattered light distribution and the ion blow off is evidence for non-classical absorption mechanisms and density scale heights of the order of 2 μm or less. The symmetry of the thermonuclear burn region is investigated by monitoring the α-particle flux in several directions, and an experiment to image the thermonuclear burn region is in process. These experiments significantly extend our data base and our understanding of laser induced thermonuclear implosions and the basic laser plasma interaction physics from the 0.4 to 0.7 TW level of previous experiments

  14. The Compressed Baryonic Matter experiment

    Directory of Open Access Journals (Sweden)

    Seddiki Sélim

    2014-04-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is a next-generation fixed-target detector which will operate at the future Facility for Antiproton and Ion Research (FAIR in Darmstadt. The goal of this experiment is to explore the QCD phase diagram in the region of high net baryon densities using high-energy nucleus-nucleus collisions. Its research program includes the study of the equation-of-state of nuclear matter at high baryon densities, the search for the deconfinement and chiral phase transitions and the search for the QCD critical point. The CBM detector is designed to measure both bulk observables with a large acceptance and rare diagnostic probes such as charm particles, multi-strange hyperons, and low mass vector mesons in their di-leptonic decay. The physics program of CBM will be summarized, followed by an overview of the detector concept, a selection of the expected physics performance, and the status of preparation of the experiment.

  15. Binary rf pulse compression experiment at SLAC

    International Nuclear Information System (INIS)

    Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

    1990-06-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here

  16. Laser acceleration

    Science.gov (United States)

    Tajima, T.; Nakajima, K.; Mourou, G.

    2017-02-01

    The fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefield with a relativistic amplitude robustly supported by the plasma. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ˜ c and ultrafastness of the laser pulse introduce the wake stability and rigidity. A large number of worldwide experiments show a rapid progress of this concept realization toward both the high-energy accelerator prospect and broad applications. The strong interest in this has been spurring and stimulating novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression, the Coherent Amplification Network, and the Relativistic Mirror Compression. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. This science has triggered a number of worldwide research centers and initiatives. Associated physics of ion acceleration, X-ray generation, and astrophysical processes of ultrahigh energy cosmic rays are reviewed. Applications such as X-ray free electron laser, cancer therapy, and radioisotope production etc. are considered. A new avenue of LWFA using nanomaterials is also emerging.

  17. Laser acceleration

    International Nuclear Information System (INIS)

    Tajima, T.; Nakajima, K.; Mourou, G.

    2017-01-01

    The fundamental idea of LaserWakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefield with a relativistic amplitude robustly supported by the plasma. While the large amplitude of wake fields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ∼ c and ultra fastness of the laser pulse introduce the wake stability and rigidity. A large number of worldwide experiments show a rapid progress of this concept realization toward both the high-energy accelerator prospect and broad applications. The strong interest in this has been spurring and stimulating novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression, the Coherent Amplification Network, and the Relativistic Mirror Compression. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. This science has triggered a number of worldwide research centers and initiatives. Associated physics of ion acceleration, X-ray generation, and astrophysical processes of ultrahigh energy cosmic rays are reviewed. Applications such as X-ray free electron laser, cancer therapy, and radioisotope production etc. are considered. A new avenue of LWFA using nano materials is also emerging.

  18. Compression of TPC data in the ALICE experiment

    International Nuclear Information System (INIS)

    Nicolaucig, A.; Mattavelli, M.; Carrato, S.

    2002-01-01

    In this paper two algorithms for the compression of the data generated by the Time Projection Chamber (TPC) detector of the ALICE experiment at CERN are described. The first algorithm is based on a lossless source code modeling technique, i.e. the original TPC signal information can be reconstructed without errors at the decompression stage. The source model exploits the temporal correlation that is present in the TPC data to reduce the entropy of the source. The second algorithm is based on a source model which is lossy if samples of the TPC signal are considered one by one. Conversely, the source model is lossless or quasi-lossless if some physical quantities that are of main interest for the experiment are considered. These quantities are the area and the location of the center of mass of each TPC signal pulse. Obviously entropy coding is applied to the set of events defined by the two source models to reduce the bit rate to the corresponding source entropy. Using TPC simulated data according to the expected ALICE TPC performance, the lossless and the lossy compression algorithms achieve a data reduction, respectively, to 49.2% and in the range of 34.2% down to 23.7% of the original data rate. The number of operations per input symbol required to implement the compression stage for both algorithms is relatively low, so that a real-time implementation embedded in the TPC data acquisition chain using low-cost integrated electronics is a realistic option to effectively reduce the data storing cost of ALICE experiment

  19. Viscoelastic behavior of basaltic ash from Stromboli volcano inferred from intermittent compression experiments

    Science.gov (United States)

    Kurokawa, A. K.; Miwa, T.; Okumura, S.; Uesugi, K.

    2017-12-01

    After ash-dominated Strombolian eruption, considerable amount of ash falls back to the volcanic conduit forming a dense near-surface region compacted by weights of its own and other fallback clasts (Patrick et al., 2007). Gas accumulation below this dense cap causes a substantial increase in pressure within the conduit, causing the volcanic activity to shift to the preliminary stages of a forthcoming eruption (Del Bello et al., 2015). Under such conditions, rheology of the fallback ash plays an important role because it controls whether the fallback ash can be the cap. However, little attention has been given to the point. We examined the rheology of ash collected at Stromboli volcano via intermittent compression experiments changing temperature and compression time/rate. The ash deformed at a constant rate during compression process, and then it was compressed without any deformation during rest process. The compression and rest processes repeated during each experiment to see rheological variations with progression of compaction. Viscoelastic changes during the experiment were estimated by Maxwell model. The results show that both elasticity and viscosity increases with decreasing porosity. On the other hand, the elasticity shows strong rate-dependence in the both compression and rest processes while the viscosity dominantly depends on the temperature, although the compression rate also affects the viscosity in the case of the compression process. Thus, the ash behaves either elastically or viscously depending on experimental process, temperature, and compression rate/time. The viscoelastic characteristics can be explained by magnitude relationships between the characteristic relaxation times and times for compression and rest processes. This indicates that the balance of the time scales is key to determining the rheological characteristics and whether the ash behaves elastically or viscously may control cyclic Strombolian eruptions.

  20. Computer-assisted experiments with a laser diode

    Energy Technology Data Exchange (ETDEWEB)

    Kraftmakher, Yaakov, E-mail: krafty@mail.biu.ac.il [Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel)

    2011-05-15

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The h/e ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a data-acquisition system, the measurements are possible in a short time. The frequency response of the laser diode is determined in the range 10-10{sup 7} Hz. The experiments are suitable for undergraduate laboratories and for classroom demonstrations on semiconductors.

  1. Computer-assisted experiments with a laser diode

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2011-01-01

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The h/e ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a data-acquisition system, the measurements are possible in a short time. The frequency response of the laser diode is determined in the range 10-10 7 Hz. The experiments are suitable for undergraduate laboratories and for classroom demonstrations on semiconductors.

  2. Compressible Convection Experiment using Xenon Gas in a Centrifuge

    Science.gov (United States)

    Menaut, R.; Alboussiere, T.; Corre, Y.; Huguet, L.; Labrosse, S.; Deguen, R.; Moulin, M.

    2017-12-01

    We present here an experiment especially designed to study compressible convection in the lab. For significant compressible convection effects, the parameters of the experiment have to be optimized: we use xenon gaz in a cubic cell. This cell is placed in a centrifuge to artificially increase the apparent gravity and heated from below. With these choices, we are able to reach a dissipation number close to Earth's outer core value. We will present our results for different heating fluxes and rotation rates. We success to observe an adiabatic gradient of 3K/cm in the cell. Studies of pressure and temperature fluctuations lead us to think that the convection takes place under the form of a single roll in the cell for high heating flux. Moreover, these fluctuations show that the flow is geostrophic due to the high rotation speed. This important role of rotation, via Coriolis force effects, in our experimental setup leads us to develop a 2D quasigeostrophic compressible model in the anelastic liquid approximation. We test numerically this model with the finite element solver FreeFem++ and compare its results with our experimental data. In conclusion, we will present our project for the next experiment in which the cubic cell will be replace by a annulus cell. We will discuss the new expected effects due to this geometry as Rossby waves and zonal flows.

  3. A Fast Faraday Cup for the Neutralized Drift Compression Experiment

    CERN Document Server

    Sefkow, Adam; Coleman, Joshua E; Davidson, Ronald C; Efthimion, Philip; Eylon, Shmuel; Gilson, Erik P; Greenway, Wayne; Henestroza, Enrique; Kwan, Joe W; Roy, Prabir K; Vanecek, David; Waldron, William; Welch, Dale; Yu, Simon

    2005-01-01

    Heavy ion drivers for high energy density physics applications and inertial fusion energy use space-charge-dominated beams which require longitudinal bunch compression in order to achieve sufficiently high beam intensity at the target. The Neutralized Drift Compression Experiment-1A (NDCX-1A) at Lawrence Berkeley National Laboratory (LBNL) is used to determine the effective limits of neutralized drift compression. NDCX-1A investigates the physics of longitudinal drift compression of an intense ion beam, achieved by imposing an initial velocity tilt on the drifting beam and neutralizing the beam's space-charge with background plasma. Accurately measuring the longitudinal compression of the beam pulse with high resolution is critical for NDCX-1A, and an understanding of the accessible parameter space is modeled using the LSP particle-in-cell (PIC) code. The design and preliminary experimental results for an ion beam probe which measures the total beam current at the focal plane as a function of time are summari...

  4. Shock compression experiments on Lithium Deuteride (LiD) single crystals

    Science.gov (United States)

    Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

    2016-12-01

    Shock compression experiments in the few hundred GPa (multi-Mbar) regime were performed on Lithium Deuteride single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ˜190 and 570 GPa along the Principal Hugoniot—the locus of end states achievable through compression by large amplitude shock waves—as well as pressure and density of reshock states up to ˜920 GPa. The experimental measurements are compared with density functional theory calculations, tabular equation of state models, and legacy nuclear driven results that have been reanalyzed using modern equations of state for the shock wave standards used in the experiments.

  5. Integrated Laser-Target Interaction Experiments on the RAL Petawatt Laser

    International Nuclear Information System (INIS)

    Patel, P. K.; Key, M. H.; Mackinnon, A. J.; Akli, K.; Berry, R.; Borghesi, M.; Brummit, P. A.; Chambers, D.; Clarke, R. J.; Damian, C.; Chen, H.; Eagleton, R.; Freeman, R.; Glenzer, S.; Gregori, G.; Heathcote, R.; Izumi, N.; Kar, S.; King, J. A.; Kock, J.; Kuba, J.; May, M.; Moon, S.; Neely, D.; Neville, D. R.; Nikroo, A.; Niles, A.; Pasley, J.; Patel, N.; Park, H. S.; Romagnani, L.; Shepherd, R.; Snavely, R. A.; Stephens, R.; Stoeckl, C.; Storm, M.; Theobald, W.; Van Maren, R.; Wilks, S. C.; Zhang, B.

    2005-01-01

    We report on two recent experimental campaigns performed on the new Petawatt laser at the Rutherford Appleton Laboratory in the UK.The laser has recently demonstrated performance characteristics of 400 J of laser energy being delivered on target in a sub 400 fs pulse, reaching a peak focal intensity on the order of 10''21 W/cm''2. The experiments covered multiplic areas of investigation including hot electron transport in planar foil and cone focus geometries, relativistic laser-solid interactions proton beam focusing and heating, and high energy K-alpha production and radiography. A somewhat novel approach was taken to the experiments in that all of the diagnostics required for the different areas of study were fielded simultaneously and operated on all shots. Thus, we were able to obtain extensive sets of measurements on a single-shot basis which provides significant benefit to our understanding of the laser-target interaction conditions and plasma properties. (Author)

  6. Optimizing pulse compressibility in completely all-fibered Ytterbium chirped pulse amplifiers for in vivo two photon laser scanning microscopy.

    Science.gov (United States)

    Fernández, A; Grüner-Nielsen, L; Andreana, M; Stadler, M; Kirchberger, S; Sturtzel, C; Distel, M; Zhu, L; Kautek, W; Leitgeb, R; Baltuska, A; Jespersen, K; Verhoef, A

    2017-08-01

    A simple and completely all-fiber Yb chirped pulse amplifier that uses a dispersion matched fiber stretcher and a spliced-on hollow core photonic bandgap fiber compressor is applied in nonlinear optical microscopy. This stretching-compression approach improves compressibility and helps to maximize the fluorescence signal in two-photon laser scanning microscopy as compared with approaches that use standard single mode fibers as stretcher. We also show that in femtosecond all-fiber systems, compensation of higher order dispersion terms is relevant even for pulses with relatively narrow bandwidths for applications relying on nonlinear optical effects. The completely all-fiber system was applied to image green fluorescent beads, a stained lily-of-the-valley root and rat-tail tendon. We also demonstrated in vivo imaging in zebrafish larvae, where we simultaneously measure second harmonic and fluorescence from two-photon excited red-fluorescent protein. Since the pulses are compressed in a fiber, this source is especially suited for upgrading existing laser scanning (confocal) microscopes with multiphoton imaging capabilities in space restricted settings or for incorporation in endoscope-based microscopy.

  7. Laser performance upgrade for precise ICF experiment in SG-Ⅲ laser facility

    Directory of Open Access Journals (Sweden)

    Wanguo Zheng

    2017-09-01

    Full Text Available The SG-Ⅲ laser facility (SG-Ⅲ is the largest laser driver for inertial confinement fusion (ICF researches in China, which has 48 beamlines and can deliver 180 kJ ultraviolet laser energy in 3 ns. In order to meet the requirements of precise physics experiments, some new functionalities need to be added to SG-Ⅲ and some intrinsic laser performances need upgrade. So at the end of SG-Ⅲ's engineering construction, the 2-year laser performance upgrade project started. This paper will introduce the newly added functionalities and the latest laser performance of SG-Ⅲ. With these function extensions and performance upgrade, SG-Ⅲ is now fully prepared for precise ICF experiments and solidly paves the way towards fusion ignition.

  8. Inverse Cerenkov laser acceleration experiment at ATF

    International Nuclear Information System (INIS)

    Wang, X.J.; Pogorelsky, I.; Fernow, R.; Kusche, K.P.; Liu, Y.; Kimura, W.D.; Kim, G.H.; Romea, R.D.; Steinhauer, L.C.

    1994-01-01

    Inverse Cerenkov laser acceleration was demonstrated using an axicon optical system at the Brookhaven Accelerator Test Facility (ATF). The ATF S-band linac and a high power 10.6 μm CO 2 laser were used for the experiment. Experimental arrangement and the laser and the electron beams synchronization are discussed. The electrons were accelerated more than 0.7 MeV for a 34 MW CO 2 laser power. More than 3.7 MeV acceleration was measured with 0.7 GW CO 2 laser power, which is more than 20 times of the previous ICA experiment. The experimental results are compared with computer program TRANSPORT simulations

  9. Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

    KAUST Repository

    Nasir, Ehson Fawad; Farooq, Aamir

    2016-01-01

    A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm

  10. Modeling ramp compression experiments using large-scale molecular dynamics simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)

    2011-10-01

    Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.

  11. Beam dynamics of the Neutralized Drift Compression Experiment-II (NDCX-II),a novel pulse-compressing ion accelerator

    International Nuclear Information System (INIS)

    Friedman, A.; Barnard, J.J.; Cohen, R.H.; Grote, D.P.; Lund, S.M.; Sharp, W.M.; Faltens, A.; Henestroza, E.; Jung, J.-Y.; Kwan, J.W.; Lee, E.P.; Leitner, M.A.; Logan, B.G.; Vay, J.-L.; Waldron, W.L.; Davidson, R.C.; Dorf, M.; Gilson, E.P.; Kaganovich, I.D.

    2009-01-01

    Intense beams of heavy ions are well suited for heating matter to regimes of emerging interest. A new facility, NDCX-II, will enable studies of warm dense matter at ∼1 eV and near-solid density, and of heavy-ion inertial fusion target physics relevant to electric power production. For these applications the beam must deposit its energy rapidly, before the target can expand significantly. To form such pulses, ion beams are temporally compressed in neutralizing plasma; current amplification factors of ∼50-100 are routinely obtained on the Neutralized Drift Compression Experiment (NDCX) at LBNL. In the NDCX-II physics design, an initial non-neutralized compression renders the pulse short enough that existing high-voltage pulsed power can be employed. This compression is first halted and then reversed by the beam's longitudinal space-charge field. Downstream induction cells provide acceleration and impose the head-to-tail velocity gradient that leads to the final neutralized compression onto the target. This paper describes the discrete-particle simulation models (1-D, 2-D, and 3-D) employed and the space-charge-dominated beam dynamics being realized.

  12. The Compressed Baryonic Matter Experiment at FAIR

    International Nuclear Information System (INIS)

    Heuser, Johann M.

    2013-01-01

    The Compressed Baryonic Matter (CBM) experiment will explore the phase diagram of strongly interacting matter in the region of high net baryon densities. The experiment is being laid out for nuclear collision rates from 0.1 to 10 MHz to access a unique wide spectrum of probes, including rarest particles like hadrons containing charm quarks, or multi-strange hyperons. The physics programme will be performed with ion beams of energies up to 45 GeV/nucleon. Those will be delivered by the SIS-300 synchrotron at the completed FAIR accelerator complex. Parts of the research programme can already be addressed with the SIS-100 synchrotron at the start of FAIR operation in 2018. The initial energy range of up to 11 GeV/nucleon for heavy nuclei, 14 GeV/nucleon for light nuclei, and 29 GeV for protons, allows addressing the equation of state of compressed nuclear matter, the properties of hadrons in a dense medium, the production and propagation of charm near the production threshold, and exploring the third, strange dimension of the nuclide chart. In this article we summarize the CBM physics programme, the preparation of the detector, and give an outline of the recently begun construction of the Facility for Antiproton and Ion Research

  13. Image splitting and remapping method for radiological image compression

    Science.gov (United States)

    Lo, Shih-Chung B.; Shen, Ellen L.; Mun, Seong K.

    1990-07-01

    A new decomposition method using image splitting and gray-level remapping has been proposed for image compression, particularly for images with high contrast resolution. The effects of this method are especially evident in our radiological image compression study. In our experiments, we tested the impact of this decomposition method on image compression by employing it with two coding techniques on a set of clinically used CT images and several laser film digitized chest radiographs. One of the compression techniques used was full-frame bit-allocation in the discrete cosine transform domain, which has been proven to be an effective technique for radiological image compression. The other compression technique used was vector quantization with pruned tree-structured encoding, which through recent research has also been found to produce a low mean-square-error and a high compression ratio. The parameters we used in this study were mean-square-error and the bit rate required for the compressed file. In addition to these parameters, the difference between the original and reconstructed images will be presented so that the specific artifacts generated by both techniques can be discerned by visual perception.

  14. Construction and characterization of a laser-driven proton beamline at GSI

    OpenAIRE

    Busold, Simon

    2014-01-01

    The thesis includes the first experiments with the new 100 TW laser beamline of the PHELIX laser facility at GSI Darmstadt to drive a TNSA (Target Normal Sheath Acceleration) proton source at GSI's Z6 experimental area. At consecutive stages a pulsed solenoid has been applied for beam transport and energy selection via chromatic focusing, as well as a radiofrequency cavity for energy compression of the bunch. This novel laser-driven proton beamline, representing a central experiment of the...

  15. Shock compression experiments on Lithium Deuteride single crystals.

    Energy Technology Data Exchange (ETDEWEB)

    Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  16. Computer-Assisted Experiments with a Laser Diode

    Science.gov (United States)

    Kraftmakher, Yaakov

    2011-01-01

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The "h/e" ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a…

  17. High-energy 4ω probe laser for laser-plasma experiments at Nova

    International Nuclear Information System (INIS)

    Glenzer, S.H.; Weiland, T.L.; Bower, J.; MacKinnon, A.J.; MacGowan, B.J.

    1999-01-01

    For the characterization of inertial confinement fusion plasmas, we implemented a high-energy 4ω probe laser at the Nova laser facility. A total energy of >50 J at 4ω, a focal spot size of order 100 μm, and a pointing accuracy of 100 μm was demonstrated for target shots. This laser provides intensities of up to 3x10 14 Wcm -2 and therefore fulfills high-power requirements for laser-plasma interaction experiments. The 4ω probe laser is now routinely used for Thomson scattering. Successful experiments were performed in gas-filled hohlraums at electron densities of n e >2x10 21 cm -3 which represents the highest density plasma so far being diagnosed with Thomson scattering. copyright 1999 American Institute of Physics

  18. Experimental investigation of dynamic compression and spallation of Cerium at pressures up to 6 GPa

    Science.gov (United States)

    Zubareva, A. N.; Kolesnikov, S. A.; Utkin, A. V.

    2014-05-01

    In this study the experiments on one-dimensional dynamic compression of Cerium (Ce) samples to pressures of 0.5 to 6 GPa using various types of explosively driven generators were conducted. VISAR laser velocimeter was used to obtain Ce free surface velocity profiles. The isentropic compression wave was registered for γ-phase of Ce at pressures lower than 0.76 GPa that corresponds to γ-α phase transition pressure in Ce. Shock rarefaction waves were also registered in several experiments. Both observations were the result of the anomalous compressibility of γ-phase of Ce. On the basis of our experimental results the compression isentrope of Ce γ-phase was constructed. Its comparison with volumetric compression curves allowed to estimate the magnitude of shear stress at dynamic compression conditions for Ce. Spall strength measurements were also conducted for several samples. They showed a strong dependence of the spall strength of Ce on the strain rate.

  19. Experimental investigation of dynamic compression and spallation of cerium at pressures up to 6 GPa

    International Nuclear Information System (INIS)

    Zubareva, A N; Kolesnikov, S A; Utkin, A V

    2014-01-01

    In this study the experiments on one-dimensional dynamic compression of Cerium (Ce) samples to pressures of 0.5 to 6 GPa using various types of explosively driven generators were conducted. VISAR laser velocimeter was used to obtain Ce free surface velocity profiles. The isentropic compression wave was registered for γ-phase of Ce at pressures lower than 0.76 GPa that corresponds to γ-α phase transition pressure in Ce. Shock rarefaction waves were also registered in several experiments. Both observations were the result of the anomalous compressibility of γ-phase of Ce. On the basis of our experimental results the compression isentrope of Ce γ-phase was constructed. Its comparison with volumetric compression curves allowed to estimate the magnitude of shear stress at dynamic compression conditions for Ce. Spall strength measurements were also conducted for several samples. They showed a strong dependence of the spall strength of Ce on the strain rate.

  20. Hydrodynamic simulations of integrated experiments planned for OMEGA/OMEGA EP laser systems

    International Nuclear Information System (INIS)

    Delettrez, J. A.; Myatt, J.; Radha, P. B.; Stoeckl, C.; Meyerhofer, D. D.

    2005-01-01

    Integrated fast-ignition experiments for the combined OMEGA/OMEGA EP laser systems have been simulated with the multidimensional hydrodynamic code DRACO. In the simplified electron transport model included in DRACO, the electrons are introduced at the pole of a 2-D simulation and transported in a straight line toward the target core, depositing their energy according to a recently published slowing-down formula.1 Simulations, including alpha transport, of an OMEGA cryogenic target designed to reach a 1-D fuel R of 500 mg/cm2 have been carried out for 1-D (clean) and, more realistic, 2-D (with nonuniformities) implosions to assess the sensitivity to energy, timing, and irradiance of the Gaussian fast-ignitor beam. The OMEGA laser system provides up to 30 kJ of compression energy, and OMEGA EP will provide two short pulse beams, each with energies up to 2.6 kJ. For the 1-D case, the neutron yield is predicted to be in excess of 1015 (compared to 1014 for no ignitor beam) over a timing range of about 80 ps. This talk will present these results and new 2-D simulation results that include the effects of realistic cryogenic target perturbations on the compressed core. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article. (Author)

  1. Lossy compression of TPC data and trajectory tracking efficiency for the ALICE experiment

    International Nuclear Information System (INIS)

    Nicolaucig, A.; Ivanov, M.; Mattavelli, M.

    2003-01-01

    In this paper a quasi-lossless algorithm for the on-line compression of the data generated by the Time Projection Chamber (TPC) detector of the ALICE experiment at CERN is described. The algorithm is based on a lossy source code modeling technique, i.e. it is based on a source model which is lossy if samples of the TPC signal are considered one by one; conversely, the source model is lossless or quasi-lossless if some physical quantities that are of main interest for the experiment are considered. These quantities are the area and the location of the center of mass of each TPC signal pulse, representing the pulse charge and the time localization of the pulse. So as to evaluate the consequences of the error introduced by the lossy compression process, the results of the trajectory tracking algorithms that process data off-line after the experiment are analyzed, in particular, versus their sensibility to the noise introduced by the compression. Two different versions of these off-line algorithms are described, performing cluster finding and particle tracking. The results on how these algorithms are affected by the lossy compression are reported. Entropy coding can be applied to the set of events defined by the source model to reduce the bit rate to the corresponding source entropy. Using TPC simulated data according to the expected ALICE TPC performance, the compression algorithm achieves a data reduction in the range of 34.2% down to 23.7% of the original data rate depending on the desired precision on the pulse center of mass. The number of operations per input symbol required to implement the algorithm is relatively low, so that a real-time implementation of the compression process embedded in the TPC data acquisition chain using low-cost integrated electronics is a realistic option to effectively reduce the data storing cost of ALICE experiment

  2. Laser program overview

    International Nuclear Information System (INIS)

    Storm, E.; Coleman, L.W.

    1985-01-01

    The objectives of the Lawrence Livermore National Laboratory Laser Fusion program are to understand and develop the science and technology of inertial confinement fusion (ICF), and to utilize ICF in short- and long-term military applications, and, in the long-term, as a candidate for central-station civilian power generation. In 1984, using the Novette laser system, the authors completed experiments showing the very favorable scaling of laser-plama interactions with short-wavelength laser light. Their Novette experiments have unequivocally shown that short laser wavelength, i.e., less than 1 μm, is required to provide the drive necessary for efficient compression, ignition, and burn of DT fusion fuel. In other experiments with Novette, the authors made the first unambiguous observation of amplified spontaneous emission in the soft x-ray regime. The authors also conducted military applications and weapons physics experiments, which they discuss in detail in the classified volume of our Laser Program Annual Report. In the second thrust, advanced laser studies, they develop and test the concepts, components, and materials for present and future laser systems. Over the years, this has meant providing the technology base and scientific advances necessary to construct and operate a succession of six evermore-powerful laser systems. The latest of these, Nova, a 100-TW/100-kJ-class laser system, was completed in 1984. The Nd:glass laser continues to be the most effective and versatile tool for ICF and weapons physics because of its scalability in energy, the ability to efficiently convert its 1=μm output to shorter wavelengths, its ability to provide flexible, controlled pulse shaping, and its capability to adapt to a variety of irradiation and focusing geometries. For these reasons, many of our advanced laser studies are in areas appropriate to solid state laser technologies

  3. Experiences with delta compression of data produced by DIII

    International Nuclear Information System (INIS)

    Henline, P.A.

    1986-01-01

    The amount of data collected for each tokamak experimental shot is rapidly increasing. This is caused by many factors, including more diagnostic experiments, reduced cost of electronics hardware (especially memory), and longer plasma duration. The design goal for the DIII-D tokamak is 25 Mbytes of data per shot. In order to store the shot data as one logical unit, the delta compression algorithm, as it was implemented at ORNL by E. Blair, is being used. Statistics on compression factors, times, and general usage will be presented for actual DIII data. Data for 8-, 10-, and 12-bit digitizers will be highlighted since this hardware is common to most sites

  4. Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

    Science.gov (United States)

    Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

    2017-08-01

    High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

  5. Modeling of laser-driven hydrodynamics experiments

    Science.gov (United States)

    di Stefano, Carlos; Doss, Forrest; Rasmus, Alex; Flippo, Kirk; Desjardins, Tiffany; Merritt, Elizabeth; Kline, John; Hager, Jon; Bradley, Paul

    2017-10-01

    Correct interpretation of hydrodynamics experiments driven by a laser-produced shock depends strongly on an understanding of the time-dependent effect of the irradiation conditions on the flow. In this talk, we discuss the modeling of such experiments using the RAGE radiation-hydrodynamics code. The focus is an instability experiment consisting of a period of relatively-steady shock conditions in which the Richtmyer-Meshkov process dominates, followed by a period of decaying flow conditions, in which the dominant growth process changes to Rayleigh-Taylor instability. The use of a laser model is essential for capturing the transition. also University of Michigan.

  6. Power balancing of multibeam laser fusion lasers

    International Nuclear Information System (INIS)

    Seka, W.; Morse, S.; Letzring, S.; Kremens, R.; Kessler, T.J.; Jaanimagi, P.; Keck, R.; Verdon, C.; Brown, D.

    1989-01-01

    The success of laser fusion depends to a good degree on the ability to compress the target to very high densities of ≥1000 times liquid DT. To achieve such compressions require that the irradiation nonuniformity must not exceed ∼1% rms over the whole time of the compression, particularly during the early phases of irradiation. The stringent requirements for the irradiation uniformity for laser fusion have been known for quite some time but until recently the energy balance was mistakenly equated to power balance. The authors describe their effort on energy balance and irradiation patterns on the target. They significantly improved the laser performance with respect to overall intensity distributions on target including the implementation of distributed (random) phase plates in each high power beam. However, the slightly varying performance of the third harmonic conversion crystals in the twenty-four beams of their laser system was generally compensated for by appropriately adjusted 1.054μm input laser energy. Computational analysis of the results of the recent high density campaign are shown

  7. Laser for fusion energy

    International Nuclear Information System (INIS)

    Holzrichter, J.F.

    1995-01-01

    Solid state lasers have proven to be very versatile tools for the study and demonstration of inertial confinement fusion principles. When lasers were first contemplated to be used for the compression of fusion fuel in the late 1950s, the laser output energy levels were nominally one joule and the power levels were 10 3 watts (pulse duration's of 10 -3 sec). During the last 25 years, lasers optimized for fusion research have been increased in power to typically 100,000 joules with power levels approaching 10 14 watts. As a result of experiments with such lasers at many locations, DT target performance has been shown to be consistent with high gain target output. However, the demonstration of ignition and gain requires laser energies of several megajoules. Laser technology improvements demonstrated over the past decade appear to make possible the construction of such multimegajoule lasers at affordable costs. (author)

  8. Compression of Ultrafast Laser Beams

    Science.gov (United States)

    2016-03-01

    Copyright 2003, AIP Publishing LLC. DOI: http://dx.doi.org/10.1063/1.1611998.) When designing the pulse shaper, the laser beam must completely fill the...for the design of future versions of this device. The easiest way to align the pulse shaper is to use the laser beam that will be shaped, without...Afterward, an ultrafast thin beam splitter is placed into the system after the diameter of the laser beam is reduced; this is done to monitor the beam

  9. Influences on target irradiation symmetry in CO2 laser-fusion experiments

    International Nuclear Information System (INIS)

    Carman, R.L.

    1981-01-01

    The existence of very steep density profiles and high upper shelf densities imply that the CO 2 laser deposits its energy spatially quite close to the ablation surface where calculations indicate that a high degree of symmetry must exist in order to achieve the necessary high compression ratios. Thus, energy transport provides only limited improvement in the ablative symmetry over that achieved in the irradiation symmetry. Current data suggests that a balance between radiation pressure and hydrodynamic pressure underestimates the density to which the CO 2 laser light penetrates for early times

  10. Progress in high-energy laser technology

    International Nuclear Information System (INIS)

    Miyanaga, Noriaki; Kitagawa, Yoneyoshi; Nakatsuka, Masahiro; Kanabe, Tadashi; Okuda, Isao

    2005-01-01

    The technological development of high-energy lasers is one of the key issues in laser fusion research. This paper reviews several technologies on the Nd:glass laser and KrF excimer laser that are being used in the current laser fusion experiments and related plasma experiments. Based on the GEKKO laser technology, a new high-energy Nd: glass laser system, which can deliver energy from 10 kJ (boad-band operation) to 20 kJ (narrow-band operation), is under construction. The key topics in KrF laser development are improved efficiency and repetitive operation, which aim at the development of a laser driven for fusion reactor. Ultra-intense-laser technology is also very important for fast ignition research. The key technology for obtaining the petawatt output with high beam quality is reviewed. Regarding the uniform laser irradiation required for high-density compression, the beam-smoothing methods on the GEKKO XII laser are reviewed. Finally, we discuss the present status of MJ-class lasers throughout the world, and summarize by presenting the feasibility of various applications of the high-energy lasers to a wide range of scientific and technological fields. (author)

  11. SBS pulse compression for excimer inertial fusion energy drivers

    International Nuclear Information System (INIS)

    Linford, G.J.

    1994-01-01

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, λ ca. 250 nm, pulse duration, τ p ca. 6 ns, bandwidth, Δλ ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, τ pp , is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, τ pp which falls in the range, 30 τ p pp p . As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration τ p . These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ''chirped,'' self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF 6 at a density, ρ ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at λ=248 nm. In order to avoid the generation of output pulses substantially shorter than τ p , the optical power in the chirped input SBS ''seed'' beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of τ p ca. ns

  12. Spherical implosion experiments on OMEGA: measurements of the cold, compressed shell

    Energy Technology Data Exchange (ETDEWEB)

    Yaakobi, B.; Smalyuk, V.A.; Delettrez, J.A.; Town, R.P.J.; Marshall, F.J.; Glebov, V.Y.; Petrasso, R.D.; Soures, J.M.; Meyerhofer, D.D.; Seka, W. [Rochester Univ., NY (United States). Lab. for Laser Energetics

    2000-07-01

    Targets in which a titanium-doped layer is incorporated into the shell provide a variety of diagnostic signatures (absorption lines, K-edge absorption, K{alpha} imaging) for determining the areal density and dimensions of the shell around peak compression. Here we apply these methods to demonstrate the improvement in target performance when SSD is implemented on slow-rising laser pulses. We introduce a new method to study the uniformity of imploded shells: using a recently developed pinhole-array x-ray spectrometer, we obtain core images at energies below and above the K-edge energy of titanium. The ratio between such images reflects the nonuniformity of the shell alone. Finally, we compare the results with those of 1-D LILAC simulations, as well as 2-D ORCHID simulations that allow for the imprinting of laser non-uniformity on the target. The experimental results are replicated much better by ORCHID than by LILAC. (authors)

  13. Particle flow of ceramic breeder pebble beds in bi-axial compression experiments

    International Nuclear Information System (INIS)

    Hermsmeyer, S.; Reimann, J.

    2002-01-01

    Pebble beds of ceramic material are investigated within the framework of developing solid breeder blankets for future fusion power plants. A thermo-mechanical characterisation of such pebble beds is mandatory for understanding the behaviour of pebble beds, and thus the overall blanket, under fusion environment conditions. The mechanical behaviour of pebble beds is typically explored with uni-axial, bi-axial and tri-axial compression experiments. The latter two types of experiment are particularly revealing since they contain explicitly, beyond a compression behaviour of the bed, information on the conditions for pebble flow, i.e. macroscopic relocation, in the pebble bed. (orig.)

  14. Dynamic study of a compressed electron layer during the hole-boring stage in a sharp-front laser interaction region

    Directory of Open Access Journals (Sweden)

    W. P. Wang

    2012-08-01

    Full Text Available This study investigates the dynamics of a compressed electron layer (CEL when a circularly polarized laser pulse with a sharp front irradiates a high-density foil. A time-dependent model for CEL motion during the hole-boring stage is proposed to describe details of the interaction for any shape of laser pulse. The opacity case, where the laser pulse is totally reflected, is investigated using this model. The results obtained are consistent with the results from particle-in-cell (PIC simulations. A relaxation distance determined by the laser-front steepness is necessary to build a stable CEL state before ions rejoin into the CEL. For the transparent case, the laser-front steepness is important for the formation of the stable CEL state at the back surface of the target. Considering the motion of ions, both the CEL and ion dynamics are important to rebalance the laser pressure and electrostatic charge-separation force as the hole-boring stage changes to the light-sail stage.

  15. Neutron measurements in the FRX-C/LSM magnetic compression experiment

    International Nuclear Information System (INIS)

    Chrien, R.E.; Baron, M.H.

    1989-01-01

    Neutron measurements are being pursued as an ion temperature diagnostic in the FRX-C/LSM Magnetic Compression Experiment. One can easily see that the d-d neutron emission is a sensitive measure of ion heating during adiabatic magnetic compression of FRCs. The reaction rate may be written as R = (1/2) n N left-angle σv right-angle, where n and N are the deuterium density and inventory. The fusion reactivity varies as left-angle σv right-angle ∝ T 5.6 for T ≅ 1 keV. For adiabatic compression, n ∝ B 1.2 and T ∝ B 0.8 so R ∝ B 5.7 in the absence of losses. The neutron yield is also sensitive to the time duration that the plasma remains near its peak temperature. 4 refs., 4 figs

  16. Observation of a New High-Pressure Solid Phase in Dynamically Compressed Aluminum

    Science.gov (United States)

    Polsin, D. N.

    2017-10-01

    Aluminum is ideal for testing theoretical first-principles calculations because of the relative simplicity of its atomic structure. Density functional theory (DFT) calculations predict that Al transforms from an ambient-pressure, face-centered-cubic (fcc) crystal to the hexagonal close-packed (hcp) and body-centered-cubic (bcc) structures as it is compressed. Laser-driven experiments performed at the University of Rochester's Laboratory for Laser Energetics and the National Ignition Facility (NIF) ramp compressed Al samples to pressures up to 540 GPa without melting. Nanosecond in-situ x-ray diffraction was used to directly measure the crystal structure at pressures where the solid-solid phase transformations of Al are predicted to occur. Laser velocimetry provided the pressure in the Al. Our results show clear evidence of the fcc-hcp and hpc-bcc transformations at 216 +/- 9 GPa and 321 +/- 12 GPa, respectively. This is the first experimental in-situ observation of the bcc phase in compressed Al and a confirmation of the fcc-hcp transition previously observed under static compression at 217 GPa. The observations indicate these solid-solid phase transitions occur on the order of tens of nanoseconds time scales. In the fcc-hcp transition we find the original texture of the sample is preserved; however, the hcp-bcc transition diminishes that texture producing a structure that is more polycrystalline. The importance of this dynamic is discussed. The NIF results are the first demonstration of x-ray diffraction measurements at two different pressures in a single laser shot. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. Multiscale modeling of beryllium: quantum mechanics and laser-driven shock experiments using novel diagnostics

    International Nuclear Information System (INIS)

    Swift, D.C.; Paisley, Dennis L.; Kyrala, George A.; Hauer, Allan

    2002-01-01

    Ab initio quantum mechanics was used to construct a thermodynamically complete and rigorous equation of state for beryllium in the hexagonal and body-centred cubic structures, and to predict elastic constants as a function of compression. The equation of state agreed well with Hugoniot data and previously-published equations of state, but the temperatures were significantly different. The hexagonal/bcc phase boundary agreed reasonably well with published data, suggesting that the temperatures in our new equation of state were accurate. Shock waves were induced in single crystals and polycrystalline foils of beryllium, by direct illumination using the TRIDENT laser at Los Alamos. The velocity history at the surface of the sample was measured using a line-imaging VISAR, and transient X-ray diffraction (TXD) records were obtained with a plasma backlighter and X-ray streak cameras. The VISAR records exhibited elastic precursors, plastic waves, phase changes and spall. Dual TXD records were taken, in Bragg and Laue orientations. The Bragg lines moved in response to compression in the uniaxial direction. Because direct laser drive was used, the results had to be interpreted with the aid of radiation hydrodynamics simulations to predict the loading history for each laser pulse. In the experiments where there was evidence of polymorphism in the VISAR record, additional lines appeared in the Bragg and Laue records. The corresponding pressures were consistent with the phase boundary predicted by the quantum mechanical equation of state for beryllium. A model of the response of a single crystal of beryllium to shock loading is being developed using these new theoretical and experimental results. This model will be used in meso-scale studies of the response of the microstructure, allowing us to develop a more accurate representation of the behaviour of polycrystalline beryllium.

  18. Femtosecond Laser Tagging Characterization of a Sweeping Jet Actuator Operating in the Compressible Regime

    Science.gov (United States)

    Peters, Christopher J.; Miles, Richard B.; Burns, Ross A.; Bathel, Brett F.; Jones, Gregory S.; Danehy, Paul M.

    2016-01-01

    A sweeping jet (SWJ) actuator operating over a range of nozzle pressure ratios (NPRs) was characterized with femtosecond laser electronic excitation tagging (FLEET), single hot-wire anemometry (HWA) and high-speed/phase-averaged schlieren. FLEET velocimetry was successfully demonstrated in a highly unsteady, oscillatory flow containing subsonic through supersonic velocities. Qualitative comparisons between FLEET and HWA (which measured mass flux since the flow was compressible) showed relatively good agreement in the external flow profiles. The spreading rate was found to vary from 0.5 to 1.2 depending on the pressure ratio. The precision of FLEET velocity measurements in the external flow field was poorer (is approximately equal to 25 m/s) than reported in a previous study due to the use of relatively low laser fluences, impacting the velocity fluctuation measurements. FLEET enabled velocity measurements inside the device and showed that choking likely occurred for NPR = 2.0, and no internal shockwaves were present. Qualitative oxygen concentration measurements using FLEET were explored in an effort to gauge the jet's mixing with the ambient. The jet was shown to mix well within roughly four throat diameters and mix fully within roughly eight throat diameters. Schlieren provided visualization of the internal and external flow fields and showed that the qualitative structure of the internal flow does not vary with pressure ratio and the sweeping mechanism observed for incompressible NPRs also probably holds for compressible NPRs.

  19. High intensity pulse self-compression in short hollow core capillaries

    OpenAIRE

    Butcher, Thomas J.; Anderson, Patrick N.; Horak, Peter; Frey, Jeremy G.; Brocklesby, William S.

    2011-01-01

    The drive for shorter pulses for use in techniques such as high harmonic generation and laser wakefield acceleration requires continual improvement in post-laser pulse compression techniques. The two most commonly used methods of pulse compression for high intensity pulses are hollow capillary compression via self-phase modulation (SPM) [1] and the more recently developed filamentation [2]. Both of these methods can require propagation distances of 1-3 m to achieve spectral broadening and com...

  20. High-energy few-cycle pulse compression through self-channeling in gases

    International Nuclear Information System (INIS)

    Hauri, C.; Merano, M.; Trisorio, A.; Canova, F.; Canova, L.; Lopez-Martens, R.; Ruchon, T.; Engquist, A.; Varju, K.; Gustafsson, E.

    2006-01-01

    Complete test of publication follows. Nonlinear spectral broadening of femtosecond optical pulses by intense propagation in a Kerr medium followed by temporal compression constitutes the Holy Grail for ultrafast science since it allows the generation of intense few-cycle optical transients from longer pulses provided by now commercially available femtosecond lasers. Tremendous progress in high-field and attosecond physics achieved in recent years has triggered the need for efficient pulse compression schemes producing few-cycle pulses beyond the mJ level. We studied a novel pulse compression scheme based on self-channeling in gases, which promises to overcome the energy constraints of hollow-core fiber compression techniques. Fundamentally, self-channeling at high laser powers in gases occurs when the self-focusing effect in the gas is balanced through the dispersion induced by the inhomogeneous refractive index resulting from optically-induced ionization. The high nonlinearity of the ionization process poses great technical challenges when trying to scale this pulse compression scheme to higher energies input energies. Light channels are known to be unstable under small fluctuations of the trapped field that can lead to temporal and spatial beam breakup, usually resulting in the generation of spectrally broad but uncompressible pulses. Here we present experimental results on high-energy pulse compression of self-channeled 40-fs pulses in pressure-gas cells. In the first experiment, performed at the Lund Laser Center in Sweden, we identified a particular self-channeling regime at lower pulse energies (0.8 mJ), in which the ultrashort pulses are generated with negative group delay dispersion (GDD) such that they can be readily compressed down to near 10-fs through simple material dispersion. Pulse compression is efficient (70%) and exhibits exceptional spatial and temporal beam stability. In a second experiment, performed at the LOA-Palaiseau in France, we

  1. Effect of spatial nonuniformity of heating on compression and burning of a thermonuclear target under direct multibeam irradiation by a megajoule laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Bel’kov, S. A.; Bondarenko, S. V. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (Russian Federation); Vergunova, G. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Garanin, S. G. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (Russian Federation); Gus’kov, S. Yu.; Demchenko, N. N.; Doskoch, I. Ya. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Zmitrenko, N. V. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Kuchugov, P. A., E-mail: pkuchugov@gmail.com; Rozanov, V. B.; Stepanov, R. V.; Yakhin, R. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-02-15

    Direct-drive fusion targets are considered at present as an alternative to targets of indirect compression at a laser energy level of about 2 MJ. In this approach, the symmetry of compression and ignition of thermonuclear fuel play the major role. We report on the results of theoretical investigation of compression and burning of spherical direct-drive targets in the conditions of spatial nonuniformity of heating associated with a shift of the target from the beam center of focusing and possible laser radiation energy disbalance in the beams. The investigation involves numerous calculations based on a complex of 1D and 2D codes RAPID, SEND (for determining the target illumination and the dynamics of absorption), DIANA, and NUT (1D and multidimensional hydrodynamics of compression and burning of targets). The target under investigation had the form of a two-layer shell (ablator made of inertial material CH and DT ice) filled with DT gas. We have determined the range of admissible variation of compression and combustion parameters of the target depending on the variation of the spatial nonuniformity of its heating by a multibeam laser system. It has been shown that low-mode (long-wavelength) perturbations deteriorate the characteristics of the central region due to less effective conversion of the kinetic energy of the target shell into the internal energy of the center. Local initiation of burning is also observed in off-center regions of the target in the case of substantial asymmetry of irradiation. In this case, burning is not spread over the entire volume of the DT fuel as a rule, which considerably reduces the thermonuclear yield as compared to that in the case of spherical symmetry and central ignition.

  2. Laser and plasma diagnostics for the OMEGA Upgrade Laser System (invited) (abstract)

    International Nuclear Information System (INIS)

    Letzring, S.A.

    1995-01-01

    The upgraded OMEGA laser system will be capable of delivering up to 30 kJ of 351-nm laser light with various temporal pulse shapes onto a variety of targets for both ICF and basic plasma physics experiments. ICF experiments will cover a wide parameter space up to near-ignition conditions, and basic interaction and plasma physics experiments will cover previously unattainable parameter spaces. The laser system is the tool with which the experiments are performed; the diagnostics, both of the laser system and the interaction between the laser and the target, form the heart of the experiment. A new suite of diagnostics is now being designed and constructed. Most of these are based on diagnostics previously fielded on the OMEGA laser system very successfully over the last ten years, but there are some new diagnostics, both for the laser and the interaction experiments, which have had to be invented. Laser system diagnostics include high-energy, full-beam calorimetry for all of the 60 beams of the upgrade; a novel, multispectral energy-measuring system for assessing the tuning of the frequency-multiplying crystals; a beam-balance diagnostic that forms the heart of the energy-balance system; and a peak power diagnostic that forms the heart of the power-balance system. Target diagnostics will include the usual time-integrated x-ray imaging systems, both pinhole cameras and x-ray microscopes; x-ray spectrometers, both imaging and spatially integrating; plamsa calorimeters, including x-ray calorimetry; and time-resolved x-ray diagnostics, both nonimaging and imaging in one and two dimensions. Neutron diagnostics will include several measurements of total yield, secondary, and possibly tertiary yield and neutron spectroscopy with several time-of-flight spectrometers. Other measurements will include ''knock-on'' particle measurements and neutron activation of shell materials as a diagnostic of compressed fuel and shell density

  3. Experiments with a laser cooled cloud of atoms

    International Nuclear Information System (INIS)

    Natarajan, Vasant; Banerjee, Ayan; Rapol, Umakant

    1999-01-01

    We discuss two experiments that can be performed using a cloud of laser-cooled and trapped atoms, namely Bose-Einstein condensation (BEC) and search for a permanent Electric Dipole Moment (EDM). BEC can be observed in Rb atoms in a magnetic trap by using forced evaporative cooling to continuously lower the temperature below the condensation limit. The cloud is cooled by preferentially ejecting the hottest atoms from a magnetic trap. The magnetic trap is loaded with laser-cooled atoms from a magneto-optic trap. The EDM experiment can be performed with a laser-cooled cloud of Yb atoms. The atoms are spin polarized and the precession of the spin is measured in the presence of a strong electric field applied perpendicular to the spin direction. The use of laser-cooled atoms should greatly enhance the sensitivity of the experiment. (author)

  4. Thermal effect of laser ablation on the surface of carbon fiber reinforced plastic during laser processing

    Science.gov (United States)

    Ohkubo, Tomomasa; Sato, Yuji; Matsunaga, Ei-ichi; Tsukamoto, Masahiro

    2018-02-01

    Although laser processing is widely used for many applications, the cutting quality of carbon fiber reinforced plastic (CFRP) decreases around the heat-affected zone (HAZ) during laser processing. Carbon fibers are exposed around the HAZ, and tensile strength decreases with increasing length of the HAZ. Some theoretical studies of thermal conductions that do not consider fluid dynamics have been performed; however, theoretical considerations that include the dynamics of laser ablation are scarce. Using removed mass and depth observed from experiments, the dynamics of laser ablation of CFRP with high-temperature and high-pressure of compressive gas is simulated herein. In this calculation, the mushroom-like shape of laser ablation is qualitatively simulated compared with experiments using a high-speed camera. Considering the removal temperature of the resin and the temperature distribution at each point on the surface, the simulation results suggest that a wide area of the resin is removed when the processing depth is shallow, and a rounded kerf is generated as the processing depth increases.

  5. Radial focusing and energy compression of a laser-produced proton beam by a synchronous rf field

    Directory of Open Access Journals (Sweden)

    Masahiro Ikegami

    2009-06-01

    Full Text Available The dynamics of a MeV laser-produced proton beam affected by a radio frequency (rf electric field has been studied. The proton beam was emitted normal to the rear surface of a thin polyimide target irradiated with an ultrashort pulsed laser with a power density of 4×10^{18}  W/cm^{2}. The energy spread was compressed to less than 11% at the full width at half maximum (FWHM by an rf field. Focusing and defocusing effects of the transverse direction were also observed. These effects were analyzed and reproduced by Monte Carlo simulations. The simulation results show that the transversely focused protons had a broad continuous spectrum, while the peaks in the proton spectrum were defocused. Based on this new information, we propose that elimination of the continuous energy component of laser-produced protons is possible by utilizing a focal length difference between the continuous spectral protons and the protons included in the spectral peak.

  6. Inertial fusion by laser

    International Nuclear Information System (INIS)

    Dautray, R.; Watteau, J.-P.

    1980-01-01

    Following a brief historical survey of research into the effects of interaction of laser with matter, the principles of fusion by inertial confinement are described and the main parameters and possible levels given. The development of power lasers is then discussed with details of performances of the main lasers used in various laboratories, and with an assessment of the respective merits of neodymium glass, carbon dioxide or iodine lasers. The phenomena of laser radiation and its interaction with matter is then described, with emphasis on the results of experiments concerned with target implosion with the object of compressing and heating the mixture of heavy hydrogen and tritium to be ignited. Finally, a review is made of future possibilities opened up by the use of large power lasers which have recently become operational or are being constructed, and the ground still to be covered before a reactor can be produced [fr

  7. Porous media experience applicable to field evaluation for compressed air energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Allen, R.D.; Gutknecht, P.J.

    1980-06-01

    A survey is presented of porous media field experience that may aid in the development of a compressed air energy storage field demonstration. Work done at PNL and experience of other groups and related industries is reviewed. An overall view of porous media experience in the underground storage of fluids is presented. CAES experience consists of site evaluation and selection processes used by groups in California, Kansas, and Indiana. Reservoir design and field evaluation of example sites are reported. The studies raised questions about compatibility with depleted oil and gas reservoirs, storage space rights, and compressed air regulations. Related experience embraces technologies of natural gas, thermal energy, and geothermal and hydrogen storage. Natural gas storage technology lends the most toward compressed air storage development, keeping in mind the respective differences between stored fluids, physical conditions, and cycling frequencies. Both fluids are injected under pressure into an aquifer to form a storage bubble confined between a suitable caprock structure and partially displaced ground water. State-of-the-art information is summarized as the necessary foundation material for field planning. Preliminary design criteria are given as recommendations for basic reservoir characteristics. These include geometric dimensions and storage matrix properties such as permeability. Suggested ranges are given for injection air temperature and reservoir pressure. The second step in developmental research is numerical modeling. Results have aided preliminary design by analyzing injection effects upon reservoir pressure, temperature and humidity profiles. Results are reported from laboratory experiments on candidate sandstones and caprocks. Conclusions are drawn, but further verification must be done in the field.

  8. Laser driven hydrodynamic instability experiments

    International Nuclear Information System (INIS)

    Remington, B.A.; Weber, S.V.; Haan, S.W.; Kilkenny, J.D.; Glendinning, S.G.; Wallace, R.J.; Goldstein, W.H.; Wilson, B.G.; Nash, J.K.

    1993-01-01

    An extensive series of experiments has been conducted on the Nova laser to measure hydrodynamic instabilities in planar foils accelerated by x-ray ablation. Single mode experiments allow a measurement of the fundamental growth rates from the linear well into the nonlinear regime. Two-mode foils allow a first direct observation of mode coupling. Surface-finish experiments allow a measurement of the evolution of a broad spectrum of random initial modes

  9. First Laser-Plasma Interaction and Hohlraum Experiments on NIF

    International Nuclear Information System (INIS)

    Dewald, E L; Glenzer, S H; Landen, O L; Suter, L J; Jones, O S; Schein, J; Froula, D; Divol, L; Campbell, K; Schneider, M S; McDonald, J W; Niemann, C; Mackinnon, A J

    2005-01-01

    Recently the first hohlraum experiments have been performed at the National Ignition Facility (NIF) in support of indirect drive Inertial Confinement Fusion (ICF) designs. The effects of laser beam smoothing by spectral dispersion (SSD) and polarization smoothing (PS) on the beam propagation in long scale gas-filled pipes has been studied at plasma scales as found in indirect drive gas filled ignition hohlraum designs. The long scale gas-filled target experiments have shown propagation over 7 mm of dense plasma without filamentation and beam break up when using full laser smoothing. Vacuum hohlraums have been irradiated with laser powers up to 6 TW, 1-9 ns pulse lengths and energies up to 17 kJ to activate several diagnostics, to study the hohlraum radiation temperature scaling with the laser power and hohlraum size, and to make contact with hohlraum experiments performed at the NOVA and Omega laser facilities. Subsequently, novel long laser pulse hohlraum experiments have tested models of hohlraum plasma filling and long pulse hohlraum radiation production. The validity of the plasma filling assessment in analytical models and in LASNEX calculations has been proven for the first time. The comparison of these results with modeling will be discussed

  10. Inelastic response of silicon to shock compression.

    Science.gov (United States)

    Higginbotham, A; Stubley, P G; Comley, A J; Eggert, J H; Foster, J M; Kalantar, D H; McGonegle, D; Patel, S; Peacock, L J; Rothman, S D; Smith, R F; Suggit, M J; Wark, J S

    2016-04-13

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

  11. Lossy compression of TPC data and trajectory tracking efficiency for the ALICE experiment

    CERN Document Server

    Nicolaucig, A; Mattavelli, M

    2003-01-01

    In this paper a quasi-lossless algorithm for the on-line compression of the data generated by the Time Projection Chamber (TPC) detector of the ALICE experiment at CERN is described. The algorithm is based on a lossy source code modeling technique, i.e. it is based on a source model which is lossy if samples of the TPC signal are considered one by one; conversely, the source model is lossless or quasi-lossless if some physical quantities that are of main interest for the experiment are considered. These quantities are the area and the location of the center of mass of each TPC signal pulse, representing the pulse charge and the time localization of the pulse. So as to evaluate the consequences of the error introduced by the lossy compression process, the results of the trajectory tracking algorithms that process data off-line after the experiment are analyzed, in particular, versus their sensibility to the noise introduced by the compression. Two different versions of these off- line algorithms are described,...

  12. SBS pulse compression for excimer inertial fusion energy drivers

    Energy Technology Data Exchange (ETDEWEB)

    Linford, G.J. [TRW Space and Electronics Group, Redondo Beach, CA (United States). Space and Technology Div.

    1994-12-31

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, {lambda} ca. 250 nm, pulse duration, {tau}{sub p} ca. 6 ns, bandwidth, {Delta}{lambda} ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, {tau}{sub pp}, is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, {tau}{sub pp} which falls in the range, 30 {tau}{sub p}<{tau}{sub pp}<100{tau}{sub p}. As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration {tau}{sub p}. These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ``chirped,`` self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF{sub 6} at a density, {rho} ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at {lambda}=248 nm. In order to avoid the generation of output pulses substantially shorter than {tau}{sub p}, the optical power in the chirped input SBS ``seed`` beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of {tau}{sub p} ca. ns.

  13. Repetitive laser fusion experiment and operation using a target injection system

    International Nuclear Information System (INIS)

    Nishimura, Yasuhiko; Komeda, Osamu; Mori, Yoshitaka

    2017-01-01

    Since 2008, a collaborative research project on laser fusion development based on a high-speed ignition method using repetitive laser has been carried out with several collaborative research institutes. This paper reports the current state of operation of high repetition laser fusion experiments, such as target introduction and control based on a target injection system that allows free falling under 1 Hz, using a high repetition laser driver that has been under research and development, as well as the measurement of targets that freely fall. The HAMA laser driver that enabled high repetition fusion experiments is a titanium sapphire laser using a diode-pumped solid-state laser KURE-I of green light output as a driver pump light source. In order to carry out high repetition laser fusion experiments, the target injection device allows free falling of deuterated polystyrene solid sphere targets of 1 mm in diameter under 1 Hz. The authors integrated the developed laser and injection system, and succeeded first in the world in making the nuclear fusion reaction continuously by hitting the target to be injected with laser, which is essential technology for future laser nuclear fusion reactor. In order to realize repetition laser fusion experiments, stable laser, target synchronization control, and target position measurement technologies are indispensable. (A.O.)

  14. Staged electron laser accelerator (STELLA) experiment at brookhaven ATF

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelsky, I V; Steenbergen, A van; Gallardo, J C [Brookhaven National Lab., Upton, NY (United States); and others

    1998-03-01

    The STELLA experiment is being prepared at the BNL Accelerator Test Facility (STF). The goal of the experiment is to demonstrate quasi-monochromatic inverse Cherenkov acceleration (ICA) of electrons bunched to the laser wavelength period. Microbunches on the order of 2 {mu}m in length separated by 10.6 {mu}m will be produced using an inverse free electron laser (IFEL) accelerator driven by a CO{sub 2} laser. The design and simulations for two phases of this experiment including demonstration of 10 MeV and 100 MeV acceleration are presented. (author)

  15. Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Wayne D

    2008-06-27

    The original goals of the Staged Electron Laser Acceleration – Laser Wakefield (STELLA-LW) program were to investigate two new methods for laser wakefield acceleration (LWFA). In pseudo-resonant LWFA (PR-LWFA), a laser pulse experiences nonlinear pulse steepening while traveling through the plasma. This steepening allows the laser pulse to generate wakefields even though the laser pulse length is too long for resonant LWFA to occur. For the conditions of this program, PR-LWFA requires a minimum laser peak power of 3 TW and a low plasma density (10^16 cm^-3). Seeded self-modulated LWFA (seeded SM-LWFA) combines LWFA with plasma wakefield acceleration (PWFA). An ultrashort (~100 fs) electron beam bunch acts as a seed in a plasma to form a wakefield via PWFA. This wakefield is subsequently amplified by the laser pulse through a self-modulated LWFA process. At least 1 TW laser power and, for a ~100-fs bunch, a plasma density ~10^17 cm^-3 are required. STELLA-LW was located on Beamline #1 at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). The ATF TW CO2 laser served as the driving laser beam for both methods. For PR-LWFA, a single bunch was to probe the wakefield produced by the laser beam. For seeded SM-LWFA, the ATF linac would produce two bunches, where the first would be the seed and the second would be the witness. A chicane would compress the first bunch to enable it to generate wakefields via PWFA. The plasma source was a short-length, gas-filled capillary discharge with the laser beam tightly focused in the center of the capillary, i.e., no laser guiding was used, in order to obtain the needed laser intensity. During the course of the program, several major changes had to be made. First, the ATF could not complete the upgrade of the CO2 laser to the 3 TW peak power needed for the PR-LWFA experiment. Therefore, the PR-LWFA experiment had to be abandoned leaving only the seeded SM-LWFA experiment. Second, the ATF discovered that the

  16. Laser wakefield accelerator experiments at LBNL

    International Nuclear Information System (INIS)

    Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Fubiani, G.; Geddes, C.G.R.; Esarey, E.; Shadwick, B.A.; Brussaard, G.J.H.; Tilborg, J. van; Chattopadhyay, S.; Wurtele, J.S.; Archambault, L.; Dickinson, M.R.; DiMaggio, S.; Short, R.; Barat, K.L.; Donahue, R.; Floyd, J.; Smith, A.; Wong, E.

    2001-01-01

    The status is presented of the laser wakefield acceleration research at the l'OASIS laboratory of the Center for Beam Physics at LBNL. Experiments have been performed on laser driven production of relativistic electron beams from plasmas using a high repetition rate (10 Hz), high power (10 TW) Ti:sapphire (0.8 μm) laser system. Large amplitude plasma waves have been excited in the self-modulated laser wakefield regime by tightly focusing (spot diameter 8 μm) a single high power (≤10 TW), ultra-short (≥50 fs) laser pulse onto a high density (>10 19 cm -3 ) pulsed gasjet (length 1.2 mm). Nuclear activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Progress on implementing the colliding pulse laser injection method is also presented. This method is expected to produce low emittance ( 7 electrons/bunch

  17. Laser fusion experiments at the Lawrence Livermore Laboratory

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.

    1975-01-01

    A short review is given of some of the important dates in the experimental fusion program at Livermore. A few of the parameters of the laser systems which are being used for these experiments are mentioned. Some information about specialized diagnostics which have been developed at the Livermore Laboratory for these experiments is described. The focusing arrangements for each of the systems are discussed. Experiments both on planar targets and on targets for laser fusion are described

  18. The development of laser fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Mima, Kunioki [Osaka Univ., Suita (Japan). Inst. of Laser Engineering

    1998-11-01

    Laser fusion research started soon after the invention of laser. In 1972, the research was declassified and nuclear fusion by laser inplosion was proposed by J. Nuckolls. Since then, 26 years has passed and laser implosion experiments demonstrated 1000 times solid density compression. By the demonstration of 1000 times solid density, the mission of the laser fusion research shifted from `implosion physics` to `ignition and high gain`, namely demonstration of fusion output of 100 times input laser energy. By the recent developments of laser technology, ultra intense laser became available and opened up a new ignition scheme which is called `Fast Ignition`. The technology for the diode pumped solid state laser (DPSSL) is developed toward a laser driver for reactor. U.S. and France are constructing MJ lasers for demonstrating ignition and burn and Osaka University is investigating the fast ignition and the equivalent plasma of confinement (EPOC) toward high gain. (author)

  19. The development of laser fusion research

    International Nuclear Information System (INIS)

    Mima, Kunioki

    1998-01-01

    Laser fusion research started soon after the invention of laser. In 1972, the research was declassified and nuclear fusion by laser inplosion was proposed by J. Nuckolls. Since then, 26 years has passed and laser implosion experiments demonstrated 1000 times solid density compression. By the demonstration of 1000 times solid density, the mission of the laser fusion research shifted from 'implosion physics' to 'ignition and high gain', namely demonstration of fusion output of 100 times input laser energy. By the recent developments of laser technology, ultra intense laser became available and opened up a new ignition scheme which is called 'Fast Ignition'. The technology for the diode pumped solid state laser (DPSSL) is developed toward a laser driver for reactor. U.S. and France are constructing MJ lasers for demonstrating ignition and burn and Osaka University is investigating the fast ignition and the equivalent plasma of confinement (EPOC) toward high gain. (author)

  20. Modeling Drift Compression in an Integrated Beam Experiment for Heavy-Ion-Fusion

    Science.gov (United States)

    Sharp, W. M.; Barnard, J. J.; Friedman, A.; Grote, D. P.; Celata, C. M.; Yu, S. S.

    2003-10-01

    The Integrated Beam Experiment (IBX) is an induction accelerator being designed to further develop the science base for heavy-ion fusion. The experiment is being developed jointly by Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory. One conceptual approach would first accelerate a 0.5-1 A beam of singly charged potassium ions to 5 MeV, impose a head-to-tail velocity tilt to compress the beam longitudinally, and finally focus the beam radiallly using a series of quadrupole lenses. The lengthwise compression is a critical step because the radial size must be controlled as the current increases, and the beam emittance must be kept minimal. The work reported here first uses the moment-based model HERMES to design the drift-compression beam line and to assess the sensitivity of the final beam profile to beam and lattice errors. The particle-in-cell code WARP is then used to validate the physics design, study the phase-space evolution, and quantify the emittance growth.

  1. Soft x-ray laser experiments at Novette Laser Facility

    International Nuclear Information System (INIS)

    Matthews, D.; Hagelstein, P.; Rosen, M.

    1984-01-01

    We discuss the results of and future plans for experiments to study the possibility of producing an x-ray laser. The schemes we have investigated are all pumped by the Novette Laser, operated at short pulse (tau/sub L/ approx. 100 psec) and an incident wavelength of lambda /sub L/ approx. 0.53 μm. We have studied the possibility of lasing at 53.6, 68.0 to 72.0, 119.0, and 153.0 eV, using the inversion methods of resonant photo-excitation, collisional excitation, and three-body recombination

  2. Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

    Science.gov (United States)

    Lanin, Aleksandr A.; Fedotov, Il'ya V.; Sidorov-Biryukov, Dmitrii A.; Doronina-Amitonova, Lyubov V.; Ivashkina, Olga I.; Zots, Marina A.; Sun, Chi-Kuang; Ömer Ilday, F.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

    2012-03-01

    Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-μm-core hollow PCF compresses 510-fs, 1070-nm light pulses to a pulse width of about 110 fs, providing a peak power in excess of 5 MW. The compressed PCF output is employed to induce a local photodisruption of corpus callosum tissues in mouse brain and is used to generate the third harmonic in brain tissues, which is captured by the PCF and delivered to a detector through the PCF cladding.

  3. Development of all solid-state, high average power ultra-short pulse laser for X-ray generation. High average power CPA system and wavefront control of ultra short laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Harayama, Sayaka; Akaoka, Katsuaki; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Maruyama, Yoichiro; Matoba, Toru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    We developed a prototype CPA laser system which is pumped by a all solid-state Nd:YAG laser. In a preliminary experiment, the output energy of 52mJ before compression was obtained when the pumping energy was 250mJ. To compensate the wavefront distortion, an adaptive optics has been developed. By using this wavefront control system, the laser beam with the distortion of 0.15{lambda} was obtained. (author)

  4. Laser driven compression and neutron generation with spherical shell targets

    International Nuclear Information System (INIS)

    Campbell, P.M.; Hammerling, P.; Johnson, R.R.; Kubis, J.J.; Mayer, F.J.

    1977-01-01

    Laser-driven implosion experiments using DT-gas-filled spherical glass-shell targets are described. Neutron yields to 5 x 10 7 are produced from implosions of small ( -- 55 μm-diameter) targets spherically illuminated with an on-target laser power of 0.4 terawatt. Nuclear reaction product diagnostics, X-ray pinhole photographs, fast-ion spectra and X-ray measurements are used in conjunction with hydrodynamic computer code simulations to investigate the implosion phenomenology as well as the target corona evolution. Simulations using completely classical effects are not able to describe the full range of experimental data. Electron or radiation preheating may be required to explain some implosion measurements. (auth.)

  5. Laser driven hydrodynamic instability experiments

    International Nuclear Information System (INIS)

    Remington, B.A.; Weber, S.V.; Haan, S.W.; Kilkenny, J.D.; Glendinning, S.G.; Wallace, R.J.; Goldstein, W.H.; Wilson, B.G.; Nash, J.K.

    1992-01-01

    We have conducted an extensive series of experiments on the Nova laser to measure hydrodynamic instabilities in planar foils accelerated by x-ray ablation. Single mode experiments allow a measurement of the fundamental growth rates from the linear well into the nonlinear regime; multimode foils allow an assessment of the degree of mode coupling; and surface-finish experiments allow a measurement of the evolution of a broad spectrum of random initial modes. Experimental results and comparisons with theory and simulations are presented

  6. Electron bunch compression and coherent effects at the SDL

    International Nuclear Information System (INIS)

    Loos, Henrik; Carr, G. Lawrence; Doyuran, Adnan; Graves, William S.; Johnson, Eric D.; Krinsky, Samuel; Rose, James; Sheehy, Brian; Shaftan, Timur V.; Skaritka, John; Yu Lihua

    2002-01-01

    The DUVFEL accelerator in the Source Development Lab of NSLS/BNL generates a high brightness electron beam from a laser driven electron source and a magnetic bunch compressor. This beam is used for different FEL experiments in SASE and future HGHG configurations. The compression of the electron beam to high peak current while preserving the transverse properties is of great importance to the performance goals of these FELs. In this paper we report on the experimental methods to characterize the longitudinal properties of the electron beam and the measured results for various settings of the DUVFEL accelerator. The observed effects on the electron beam spectra and time profiles during compression are most likely due to coherent effects while their exact origin is still subject of ongoing investigation

  7. Laboratory astrophysics. Model experiments of astrophysics with large-scale lasers

    International Nuclear Information System (INIS)

    Takabe, Hideaki

    2012-01-01

    I would like to review the model experiment of astrophysics with high-power, large-scale lasers constructed mainly for laser nuclear fusion research. The four research directions of this new field named 'Laser Astrophysics' are described with four examples mainly promoted in our institute. The description is of magazine style so as to be easily understood by non-specialists. A new theory and its model experiment on the collisionless shock and particle acceleration observed in supernova remnants (SNRs) are explained in detail and its result and coming research direction are clarified. In addition, the vacuum breakdown experiment to be realized with the near future ultra-intense laser is also introduced. (author)

  8. Investigations concerning the applicability of X-ray flash interference and laser technology to shock-induced solidification of organic liquids

    International Nuclear Information System (INIS)

    Krehl, Peter; Schaaffs, Werner

    By a dielectric discharge through a thin layer of liquid a hot plasma is created, which expands very fast and builds up around a compression ring of very highly compressed matter. X-ray flash interferences and laser light are applied to investigate the structure of the compression rings. To perform investigation of the fine structure, an X-ray flash machine was developed which permits to obtain with a single flash in less than 1μs Laue patterns of monocrystals, and Debye-Scherrer patterns of polycrystalline substances. The investigation of the compression rings in diverse substances by laser light resulted that the optical transparency and solidification is different in different regions of the compression ring. Therefore important hints for experiments with X-ray flash interferences were obtained

  9. Dynamic Compression Experiments on Hydrogen and Deuterium in the Warm Dense Liquid.

    Science.gov (United States)

    Desjarlais, Michael; McCoy, Chad; Cochrane, Kyle; Mattsson, Thomas; Knudson, Marcus; Redmer, Ronald

    2017-06-01

    Recently a shock-ramp platform has been developed on the Z Accelerator to access off-Hugoniot states in liquids. The accelerator delivers a two-step current pulse; the first accelerates the electrode to a constant velocity, which upon impact with the sample cell creates a well-defined shock, the subsequent current rise produces ramp compression from the initially shocked state producing relatively cool (1-2 kK), high pressure (>300 GPa), high compression (10 to 15-fold compression) states. This technique allows experimental access to the region of phase space where hydrogen is predicted to undergo a first-order phase transition from an insulating molecular-like to a conducting atomic-like liquid. Here we discuss the experimental platform, survey various theoretical predictions for the liquid-liquid, insulator-to-metal transition in hydrogen, and present results of experiments on both deuterium and hydrogen that clearly show an abrupt transition to a metallic state. We also present results from recent experiments at higher temperatures (3-4 kK) and compare the observations to both first-principles theory and previous step-wise loading experiments that exhibited a minimum metallic conductivity. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  10. Optical pulse compression

    International Nuclear Information System (INIS)

    Glass, A.J.

    1975-01-01

    The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

  11. Toluene laser-induced fluorescence imaging of compressible flows in an expansion tube

    Science.gov (United States)

    Miller, V. A.; Gamba, M.; Mungal, M. G.; Hanson, R. K.; Mohri, K.; Schulz, C.

    2011-11-01

    Laser-induced fluorescence (LIF) imaging using toluene as a tracer molecule has been developed for high-speed, low-to-moderate enthalpy conditions in the Stanford 6-inch Expansion Tube. The approach is demonstrated on three canonical compressible flow configurations: (i) supersonic flow over a 20° wedge, (ii) around a cylinder, and (iii) a supersonic boundary layer. Under constant-pressure conditions, toluene LIF offers unique sensitivity to temperature and can therefore be used as an accurate thermometry diagnostic for supersonic flows; on the other hand, for variable-pressure flow fields (e.g., flow around a blunt body), toluene LIF imaging is demonstrated to be an effective flow visualization tool. The three configurations selected demonstrate the diagnostic in these two capacities. For all configurations considered in the study, toluene (0.6% by volume) is seeded into a nitrogen freestream at a Mach number ~ 2.2, T ~ 500K, and p ~ 1.5 bar. A frequency-quadrupled pulsed Nd:YAG laser is used to excite the tracer, and the resulting fluorescence is captured by an ICCD camera. Synthetic fluorescence signals from CFD solutions of each case have been computed and compare favorably to measured signals. Sponsored by DoE PSAAP at Stanford University.

  12. Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

    International Nuclear Information System (INIS)

    Ghosh, P.

    2015-01-01

    The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of 1292 double sided silicon micro-strip sensors. For the quality assurance of produced prototype sensors a laser test system (LTS) has been developed. The aim of the LTS is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype sensors which are tested with the LTS so far have 256 strips with a pitch of 50 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm , wavelength = 1060 nm). The pulse with duration (≈ 10 ns) and power (≈ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Laser scans different prototype sensors is reported

  13. Impedance-match experiments using high intensity lasers

    International Nuclear Information System (INIS)

    Holmes, N.C.; Trainor, R.J.; Anderson, R.A.; Veeser, L.R.; Reeves, G.A.

    1981-01-01

    The results of a series of impedance-match experiments using copper-aluminum targets irradiated using the Janus Laser Facility are discussed. The results are compared to extrapolations of data obtained at lower pressures using impact techniques. The sources of errors are described and evaluated. The potential of lasers for high accuracy equation of state investigations are discussed

  14. Laser fusion

    International Nuclear Information System (INIS)

    Eliezer, S.

    1982-02-01

    In this paper, the physics of laser fusion is described on an elementary level. The irradiated matter consists of a dense inner core surrounded by a less dense plasma corona. The laser radiation is mainly absorbed in the outer periphery of the plasma. The absorbed energy is transported inward to the ablation surface where plasma flow is created. Due to this plasma flow, a sequence of inward going shock waves and heat waves are created, resulting in the compression and heating of the core to high density and temperature. The interaction physics between laser and matter leading to thermonuclear burn is summarized by the following sequence of events: Laser absorption → Energy transport → Compression → Nuclear Fusion. This scenario is shown in particular for a Nd:laser with a wavelength of 1 μm. The wavelength scaling of the physical processes is also discussed. In addition to the laser-plasma physics, the Nd high power pulsed laser is described. We give a very brief description of the oscillator, the amplifiers, the spatial filters, the isolators and the diagnostics involved. Last, but not least, the concept of reactors for laser fusion and the necessary laser system are discussed. (author)

  15. Shuttle Laser Technology Experiment Facility (LTEF)-to-airplane lasercom experiment: Airplane considerations

    Science.gov (United States)

    Kalil, Ford

    1990-01-01

    NASA is considering the use of various airplanes for a Shuttle Laser Technology Experiment Facility (LTEF)-to-Airplane laser communications experiment. As supporting documentation, pertinent technical details are included about the potential use of airplanes located at Ames Research Center and Wallops Flight Facility. The effects and application of orbital mechanics considerations are also presented, including slant range, azimuth, elevation, and time. The pros and cons of an airplane equipped with a side port with a bubble window versus a top port with a dome are discussed.

  16. Experience with compressed air system of Dhruva and Cirus

    International Nuclear Information System (INIS)

    Shelar, V.G.; Patil, U.D.; Singh, V.K.; Zope, A.K.; Kharpate, A.V.

    2006-01-01

    Dhruva and Cirus reactors have independent compressed air plants with provision for sharing. Dhruva has the reciprocating oil free air compressors where as Cirus has oil lubricated compressors. Over the years, several improvements have been done in the equipments to combat various problems, among these noise mitigation in Dhruva and measures to extend life of compressors in Cirus and also incidence of discharge header catching fire are interesting. This paper details these experiences. (author)

  17. Pulse compression by Raman induced cavity dumping

    International Nuclear Information System (INIS)

    De Rougemont, F.; Xian, D.K.; Frey, R.; Pradere, F.

    1985-01-01

    High efficiency pulse compression using Raman induced cavity dumping has been studied theoretically and experimentally. Through stimulated Raman scattering the electromagnetic energy at a primary frequency is down-converted and extracted from a storage cavity containing the Raman medium. Energy storage may be achieved either at the laser frequency by using a laser medium inside the storage cavity, or performed at a new frequency obtained through an intracavity nonlinear process. The storage cavity may be dumped passively through stimulated Raman scattering either in an oscillator or in an amplifier. All these cases have been studied by using a ruby laser as the pump source and compressed hydrogen as the Raman scatter. Results differ slightly accordingly to the technique used, but pulse shortenings higher than 10 and quantum efficiencies higher than 80% were obtained. This method could also be used with large power lasers of any wavelength from the ultraviolet to the farinfrared spectral region

  18. Laser experiments in light cloudiness with the geostationary satellite ARTEMIS

    Science.gov (United States)

    Kuzkov, V.; Kuzkov, S.; Sodnik, Z.

    2016-08-01

    The geostationary satellite ARTEMIS was launched in July 2001. The satellite is equipped with a laser communication terminal, which was used for the world's first inter-satellite laser communication link between ARTEMIS and the low earth orbit satellite SPOT-4. Ground-to-space laser communication experiments were also conducted under various atmospheric conditions involving ESA's optical ground station. With a rapidly increasing volume of information transferred by geostationary satellites, there is a rising demand for high-speed data links between ground stations and satellites. For ground-to-space laser communications there are a number of important design parameters that need to be addressed, among them, the influence of atmospheric turbulence in different atmospheric conditions and link geometries. The Main Astronomical Observatory of NAS of Ukraine developed a precise computer tracking system for its 0.7 m AZT-2 telescope and a compact laser communication package LACES (Laser Atmosphere and Communication experiments with Satellites) for laser communication experiments with geostationary satellites. The specially developed software allows computerized tracking of the satellites using their orbital data. A number of laser experiments between MAO and ARTEMIS were conducted in partial cloudiness with some amount of laser light observed through clouds. Such conditions caused high break-up (splitting) of images from the laser beacon of ARTEMIS. One possible explanation is Raman scattering of photons on molecules of a water vapor in the atmosphere. Raman scattering causes a shift in a wavelength of the photons.In addition, a different value for the refraction index appears in the direction of the meridian for the wavelength-shifted photons. This is similar to the anomalous atmospheric refraction that appears at low angular altitudes above the horizon. We have also estimated the atmospheric attenuation and the influence of atmospheric turbulence on observed results

  19. Miniature proportional counter for compression measurements of laser-fusion targets

    International Nuclear Information System (INIS)

    Lane, S.M.; Dellis, J.H.; Bennett, C.K.; Campbell, E.M.

    1981-10-01

    Direct drive laser fusion targets consisting of DT gas encapsulated in glass microshells produce 14.1 MeV neutrons that can interact with silicon-28 nuclei in the glass to produce a 2.2 minute aluminum-28 activity. From the number of 28 Al nuclei created and the neutron yield, the compressed glass areal density can be found. To determine the number of activated atoms created, we collect approximately one-half of the target debris on a thin metal foil which is transferred to our beta-gamma coincidence detector. This detector consists of a 25 cm x 25 cm NaI(Tl) crystal having a 5 cm x 15 cm well. We have recently built a miniature proportional counter that fits into this well and is used to detect beta particles. It is constructed of .025 cm thick copper and has nine separate chambers through which methane flows. The coincidence background is 0.14 cpm and the measured beta efficiency is 45%. We are now building a .0125 cm thick counter made of aluminum having a predicted efficiency of > 90%

  20. Ultrasound-guided laser thermal ablation in the treatment of autonomous hyperfunctioning thyroid nodules and compressive nontoxic nodular goiter.

    Science.gov (United States)

    Spiezia, Stefano; Vitale, Giovanni; Di Somma, Carolina; Pio Assanti, Angelo; Ciccarelli, Antonio; Lombardi, Gaetano; Colao, Annamaria

    2003-10-01

    Percutaneous laser thermal ablation (LTA) has been applied in several tumors. In this study we evaluated the safety and long-term efficacy of LTA in the treatment of benign thyroid nodules. Seven patients with autonomous hyperfunctioning thyroid nodule (group A) and five patients with compressive nodular goiter (group B) were treated with LTA. Up to three needles were positioned centrally in the thyroid nodule and laser fiber was placed in the lumen of the needle. Laser illumination was performed reaching a maximal energy deposition of 1800 J per fiber. Thyroid nodule volume, endocrinologic, and clinical evaluation were performed at baseline, 3, and 12 months after the treatment. Scintigraphy was performed at diagnosis and 12 months after the first session in group A. In group A, mean thyroid volume decreased from 3.15 +/- 1.26 mL to 0.83 +/- 0.49 mL (p thyroid volume decreased from 11.14 +/- 4.99 mL to 3.73 +/- 1.47 mL (p thyroid nodules.

  1. Laser-plasma interactions in magnetized environment

    Science.gov (United States)

    Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

    2018-05-01

    Propagation and scattering of lasers present new phenomena and applications when the plasma medium becomes strongly magnetized. With mega-Gauss magnetic fields, scattering of optical lasers already becomes manifestly anisotropic. Special angles exist where coherent laser scattering is either enhanced or suppressed, as we demonstrate using a cold-fluid model. Consequently, by aiming laser beams at special angles, one may be able to optimize laser-plasma coupling in magnetized implosion experiments. In addition, magnetized scattering can be exploited to improve the performance of plasma-based laser pulse amplifiers. Using the magnetic field as an extra control variable, it is possible to produce optical pulses of higher intensity, as well as compress UV and soft x-ray pulses beyond the reach of other methods. In even stronger giga-Gauss magnetic fields, laser-plasma interaction enters a relativistic-quantum regime. Using quantum electrodynamics, we compute a modified wave dispersion relation, which enables correct interpretation of Faraday rotation measurements of strong magnetic fields.

  2. Self-compression of spatially limited laser pulses in a system of coupled light-guides

    Science.gov (United States)

    Balakin, A. A.; Litvak, A. G.; Mironov, V. A.; Skobelev, S. A.

    2018-04-01

    The self-action features of wave packets propagating in a 2D system of equidistantly arranged fibers are studied analytically and numerically on the basis of the discrete nonlinear Schrödinger equation. Self-consistent equations for the characteristic scales of a Gaussian wave packet are derived on the basis of the variational approach, which are proved numerically for powers P beams become filamented, and their amplitude is limited due to the nonlinear breaking of the interaction between neighboring light-guides. This makes it impossible to collect a powerful wave beam in a single light-guide. Variational analysis shows the possibility of the adiabatic self-compression of soliton-like laser pulses in the process of 3D self-focusing on the central light-guide. However, further increase of the field amplitude during self-compression leads to the development of longitudinal modulation instability and the formation of a set of light bullets in the central fiber. In the regime of hollow wave beams, filamentation instability becomes predominant. As a result, it becomes possible to form a set of light bullets in optical fibers located on the ring.

  3. Particle flow of ceramic breeder pebble beds in bi-axial compression experiments

    International Nuclear Information System (INIS)

    Hermsmeyer, S.; Reimann, J.

    2002-01-01

    Pebble beds of Tritium breeding ceramic material are investigated within the framework of developing solid breeder blankets for future nuclear fusion power plants. For the thermo-mechanical characterisation of such pebble beds, bed compression experiments are the standard tools. New bi-axial compression experiments on 20 and 30 mm high pebble beds show pebble flow effects much more pronounced than in previous 10 mm beds. Owing to the greater bed height, conditions are reached where the bed fails in cross direction and unhindered flow of the pebbles occurs. The paper presents measurements for the orthosilicate and metatitanate breeder materials that are envisaged to be used in a solid breeder blanket. The data are compared with calculations made with a Drucker-Prager soil model within the finite-element code ABAQUS, calibrated with data from other experiments. It is investigated empirically whether internal bed friction angles can be determined from pebble beds of the considered heights, which would simplify, and broaden the data base for, the calibration of the Drucker-Prager pebble bed models

  4. Formation of nanosecond SBS-compressed pulses for pumping an ultra-high power parametric amplifier

    Science.gov (United States)

    Kuz’min, A. A.; Kulagin, O. V.; Rodchenkov, V. I.

    2018-04-01

    Compression of pulsed Nd : glass laser radiation under stimulated Brillouin scattering (SBS) in perfluorooctane is investigated. Compression of 16-ns pulses at a beam diameter of 30 mm is implemented. The maximum compression coefficient is 28 in the optimal range of laser pulse energies from 2 to 4 J. The Stokes pulse power exceeds that of the initial laser pulse by a factor of about 11.5. The Stokes pulse jitter (fluctuations of the Stokes pulse exit time from the compressor) is studied. The rms spread of these fluctuations is found to be 0.85 ns.

  5. LPI Experiments at the Nike Laser*

    Science.gov (United States)

    Weaver, J.; Oh, J.; Afeyan, B.; Phillips, L.; Seely, J.; Brown, C.; Karasik, M.; Serlin, V.; Obenschain, S.; Chan, L.-Y.; Kehne, D.; Brown, D.; Schmitt, A.; Velikovich, A.; Feldman, U.; Holland, G.; Aglitskiy, Y.

    2007-11-01

    Advanced implosion designs under development at NRL for direct drive inertial confinement fusion incorporate high intensity pulses from a krypton-fluoride (KrF) laser to achieve significant gain with lower total laser energy (Etot˜500 kJ). These designs will be affected by the thresholds and magnitudes of laser plasma instabilities (LPI). The Nike laser can create short, high intensity pulses (t 10^15 W/cm^2) to explore how LPI will be influenced by the deep UV (248 nm), broad bandwidth (2-3 THz), and induced spatial incoherence beam smoothing of the NRL KrF laser systems. Previous results demonstrated no visible/VUV signatures of two-plasmon decay (2φp) for overlapped intensities ˜2x10^15 W/cm^2. We have increased the laser intensity and expanded the range of targets and diagnostics. Single and double pulse experiments are being planned with solid, foam, and cryogenic targets. In addition to spectrometers to study SRS, 2φp, SBS, and the parametric decay instability, hard x-ray spectrometers (hν>2 keV) and a scintillator/photomultiplier array (hν>10 keV) have been deployed to examine hot electron generation. *Work supported by U. S. DoE.

  6. Neutron scattering experiments of the ionic crystal deformed plastically with uniaxial compression under high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Yoshinori; Minakawa, Nobuaki; Aizawa, Kazuya; Ozawa, Kunio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-04-01

    As an aim of huge growth of alkali halide (AH) single crystal, a mosaic structure of small size AH single crystal deformed plastically with uniaxial compression under high temperature was evaluated due to its neutron irradiation experiment. Using TAS-2 installed at JRR-3M guide hole of Japan Atomic Energy Research Institute, locking curve at a representative face factor of the specimen was measured to observe the mosaic structure accompanied with expansion of the crystal due to compression. As a result, though the specimen before compression could be supposed to be divided to some parts already, the locking curve under 10 sec. of compression time showed already some fracture to divisions to suppose finer degradation of the crystal, and division of the locking curve at 600 sec. of compression time could be observed onto its 220 face. And, every compressed specimens showed some changes of crystallization method from standard sample. (G.K.)

  7. Observations of subpicosecond dynamics in GaAlAs laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Stix, M.S.; Kesler, M.P.; Ippen, E.P.

    1986-06-23

    We present results of pump-probe experiments on GaAlAs laser diodes indicating a 0.9-ps relaxation time associated with the device transmission. Subpicosecond, tunable near infrared pulses obtained by fiber compression were used to carry out the experiments. The data strongly support a model in which a nonequilibrium carrier temperature in the active layer is responsible for the observed signal.

  8. Supernova Hydrodynamics on the Omega Laser. Final report

    International Nuclear Information System (INIS)

    Drake, R. Paul

    2004-01-01

    (B204)The fundamental motivation for our work is that supernovae are not well understood. Recent observations have clarified the depth of our ignorance, by producing observed phenomena that current theory and computer simulations cannot reproduce. Such theories and simulations involve, however, a number of physical mechanisms that have never been studied in isolation. We perform experiments, in compressible hydrodynamics and radiation hydrodynamics, relevant to supernovae and supernova remnants. These experiments produce phenomena in the laboratory that are believed, based on simulations, to be important to astrophysics but that have not been directly observed in either the laboratory or in an astrophysical system. During the period of this grant, we have focused on the scaling of an astrophysically relevant, radiative-precursor shock, on preliminary studies of collapsing radiative shocks, and on the multimode behavior and the three-dimensional, deeply nonlinear evolution of the Rayleigh-Taylor (RT) instability at a decelerating, embedded interface. These experiments required strong compression and decompression, strong shocks (Mach ∼10 or greater), flexible geometries, and very smooth laser beams, which means that the 60-beam Omega laser is the only facility capable of carrying out this program

  9. Laser-generated shock-wave experiments in metals above 1 TPa

    International Nuclear Information System (INIS)

    Trainor, R.J.; Shaner, J.W.; Auerbach, J.M.; Phillion, D.W.

    1978-01-01

    Some initial experiments are described which form part of a new program aimed at significantly extending the range of high pressures and densities which may be explored in laboratory equation-of-state (EOS) experiments. These experiments will utilize high-energy lasers, such as those employed in the Laser Fusion Program at Lawrence Livermore Laboratory (LLL), to generate intense shock waves in materials of interest

  10. Compact toroid formation, compression, and acceleration

    International Nuclear Information System (INIS)

    Degnan, J.H.; Peterkin, R.E. Jr.; Baca, G.P.; Beason, J.D.; Bell, D.E.; Dearborn, M.E.; Dietz, D.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Hackett, K.E.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Sovinec, C.R.; Turchi, P.J.; Bird, G.; Coffey, S.K.; Seiler, S.W.; Chen, Y.G.; Gale, D.; Graham, J.D.; Scott, M.; Sommars, W.

    1993-01-01

    Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a magnetic confinement fusion program like most spheromak efforts. Rather, the ultimate goal of the present program is to compress toroids to high mass density and magnetic field intensity, and to accelerate the toroids to high speed. There are a variety of applications for compressed, accelerated toroids including fast opening switches, x-radiation production, radio frequency (rf) compression, as well as charge-neutral ion beam and inertial confinement fusion studies. Experiments performed to date to form and accelerate toroids have been diagnosed with magnetic probe arrays, laser interferometry, time and space resolved optical spectroscopy, and fast photography. Parts of the experiment have been designed by, and experimental results are interpreted with, the help of two-dimensional (2-D), time-dependent magnetohydrodynamic (MHD) numerical simulations. When not driven by a second discharge, the toroids relax to a Woltjer--Taylor equilibrium state that compares favorably to the results of 2-D equilibrium calculations and to 2-D time-dependent MHD simulations. Current, voltage, and magnetic probe data from toroids that are driven by an acceleration discharge are compared to 2-D MHD and to circuit solver/slug model predictions. Results suggest that compact toroids are formed in 7--15 μsec, and can be accelerated intact with material species the same as injected gas species and entrained mass ≥1/2 the injected mass

  11. Precision operation of the Nova laser for fusion experiments

    International Nuclear Information System (INIS)

    Caird, J.A.; Ehrlich, R.B.; Hermes, G.L.; Landen, O.L.; Laumann, C.W.; Lerche, R.A.; Miller, J.L.; Murray, J.E.; Nielsen, N.D.; Powell, H.T.; Rushford, M.C.; Saunders, R.L.; Thompson, C.E.; VanArsdall, P.J.; Vann, C.S.; Weiland, T.L.

    1994-01-01

    The operation of a Neodymium glass laser of a special design for fusion experiments is improved by a better pulse synchronization, the gain stabilization, and the laser diagnostics. We used sensor upgrading and antifriction coating of focusing lenses. The pointing accuracy of the Nova laser meets now our goal for precision operation. (AIP) copyright 1994 American Institute of Physics

  12. Shock-hydrodynamics experiments on the Nova laser

    International Nuclear Information System (INIS)

    Miller, P.; Peyser, T.; Stry, P.; Budil, K.; Wojtowicz, D.; Burke, E.

    1995-08-01

    We have conducted shock-induced hydrodynamics experiments using the Nova laser at Lawrence Livermore National Laboratory. The laser provides a high-enthalpy source by depositing its energy (about 22 kJ) in a small gold cavity called a Hohlraum. The Hohlraum serves as a driver section, launching very strong (M ∼ 20) shocks into millimeter-scale cylindrical ''shock tubes.'' The flow is imaged radiographically by an electronic framing camera, using a laser-generated x-ray source. Several topics have been addressed with this configuration, including shock-induced mixing at density interfaces (seeded with a variety of perturbations); the development of high-speed, shaped-charge-like jets; the effects of geometry on the planarity of the generated shocks; and shock-shock interactions which develop in the flows. This paper describes the general configuration of our experiments, presents an overview of the high-speed jet work, discusses some of our findings, and compares our results with computer simulations

  13. Study of compact X-ray laser pumped by pulse-train laser. Double-target experiment

    International Nuclear Information System (INIS)

    Yamaguchi, Naohiro; Fujikawa, Chiemi; Hara, Tamio

    2000-01-01

    We have been developing a tabletop x-ray laser based on the recombination plasma scheme. An advanced experiment has been started to improve x-ray laser output substantially. Two 11-mm-long laser produced plasmas were produced so that their axis aligned into a line, the double-target configuration. X-ray intensity of the 15.47 nm transition line of the Li-like Al ion has been enhanced in the double-target configuration. (author)

  14. Point-Cloud Compression for Vehicle-Based Mobile Mapping Systems Using Portable Network Graphics

    Science.gov (United States)

    Kohira, K.; Masuda, H.

    2017-09-01

    A mobile mapping system is effective for capturing dense point-clouds of roads and roadside objects Point-clouds of urban areas, residential areas, and arterial roads are useful for maintenance of infrastructure, map creation, and automatic driving. However, the data size of point-clouds measured in large areas is enormously large. A large storage capacity is required to store such point-clouds, and heavy loads will be taken on network if point-clouds are transferred through the network. Therefore, it is desirable to reduce data sizes of point-clouds without deterioration of quality. In this research, we propose a novel point-cloud compression method for vehicle-based mobile mapping systems. In our compression method, point-clouds are mapped onto 2D pixels using GPS time and the parameters of the laser scanner. Then, the images are encoded in the Portable Networking Graphics (PNG) format and compressed using the PNG algorithm. In our experiments, our method could efficiently compress point-clouds without deteriorating the quality.

  15. POINT-CLOUD COMPRESSION FOR VEHICLE-BASED MOBILE MAPPING SYSTEMS USING PORTABLE NETWORK GRAPHICS

    Directory of Open Access Journals (Sweden)

    K. Kohira

    2017-09-01

    Full Text Available A mobile mapping system is effective for capturing dense point-clouds of roads and roadside objects.Point-clouds of urban areas, residential areas, and arterial roads are useful for maintenance of infrastructure, map creation, and automatic driving. However, the data size of point-clouds measured in large areas is enormously large. A large storage capacity is required to store such point-clouds, and heavy loads will be taken on network if point-clouds are transferred through the network. Therefore, it is desirable to reduce data sizes of point-clouds without deterioration of quality. In this research, we propose a novel point-cloud compression method for vehicle-based mobile mapping systems. In our compression method, point-clouds are mapped onto 2D pixels using GPS time and the parameters of the laser scanner. Then, the images are encoded in the Portable Networking Graphics (PNG format and compressed using the PNG algorithm. In our experiments, our method could efficiently compress point-clouds without deteriorating the quality.

  16. Understanding Turbulence in Compressing Plasmas and Its Exploitation or Prevention

    Science.gov (United States)

    Davidovits, Seth

    Unprecedented densities and temperatures are now achieved in compressions of plasma, by lasers and by pulsed power, in major experimental facilities. These compressions, carried out at the largest scale at the National Ignition Facility and at the Z Pulsed Power Facility, have important applications, including fusion, X-ray production, and materials research. Several experimental and simulation results suggest that the plasma in some of these compressions is turbulent. In fact, measurements suggest that in certain laboratory plasma compressions the turbulent energy is a dominant energy component. Similarly, turbulence is dominant in some compressing astrophysical plasmas, such as in molecular clouds. Turbulence need not be dominant to be important; even small quantities could greatly influence experiments that are sensitive to mixing of non-fuel into fuel, such as compressions seeking fusion ignition. Despite its important role in major settings, bulk plasma turbulence under compression is insufficiently understood to answer or even to pose some of the most fundamental questions about it. This thesis both identifies and answers key questions in compressing turbulent motion, while providing a description of the behavior of three-dimensional, isotropic, compressions of homogeneous turbulence with a plasma viscosity. This description includes a simple, but successful, new model for the turbulent energy of plasma undergoing compression. The unique features of compressing turbulence with a plasma viscosity are shown, including the sensitivity of the turbulence to plasma ionization, and a "sudden viscous dissipation'' effect which rapidly converts plasma turbulent energy into thermal energy. This thesis then examines turbulence in both laboratory compression experiments and molecular clouds. It importantly shows: the possibility of exploiting turbulence to make fusion or X-ray production more efficient; conditions under which hot-spot turbulence can be prevented; and a

  17. Omega experiments and preparation for moderate-gain direct-drive experiments on Nif

    International Nuclear Information System (INIS)

    Mr Crory, R.L.; Bahr, R.E.; Boehly, T.R.

    2000-01-01

    Direct-drive laser-fusion ignition experiments rely on detailed understanding and control of irradiation uniformity, Rayleigh-Taylor instability, and target fabrication. LLE is investigating various theoretical aspects of a direct-drive NIF ignition target based on an 'all-DT' design: a spherical target of ∼ 3.5 mm diameter, 1 to 2 μm if CH wall thickness, and a ∼ 350 μm DT-ice layer near the triple point of DT (μ19K). OMEGA experiments are designed to address the critical issues related to direct-drive laser fusion and to provide the necessary data to validate the predictive capability of LLE computer codes. The future cryogenic targets used on OMEGA are hydrodynamically equivalent to those planned for the NIF. The current experimental studies on OMEGA address all of the essential components of direct-drive laser fusion: irradiation uniformity and laser imprinting, Rayleigh-Taylor growth and saturation, compressed core performance and shell-fuel mixing, laser-plasma interactions and their effect on target performance, and cryogenic target fabrication and handling. (authors)

  18. Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

    2016-11-15

    Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

  19. Final Report 02-ERD-033: Rapid Resolidification of Metals using Dynamic Compression

    International Nuclear Information System (INIS)

    Streitz, F H; Nguyen, J H; Orlikowski, D; Minich, R; Moriarty, J A; Holmes, N C

    2005-01-01

    The purpose of this project is to develop a greater understanding of the kinetics involved during a liquid-solid phase transition occurring at high pressure and temperature. Kinetic limitations are known to play a large role in the dynamics of solidification at low temperatures, determining, e.g., whether a material crystallizes upon freezing or becomes an amorphous solid. The role of kinetics is not at all understood in transitions at high temperature when extreme pressures are involved. In order to investigate time scales during a dynamic compression experiment we needed to create an ability to alter the length of time spent by the sample in the transition region. Traditionally, the extreme high-pressure phase diagram is studied through a few static and dynamic techniques: static compression involving diamond anvil cells (DAC) [1], shock compression [2, 3], and quasi-isentropic compression [4, 5, 6, 7, 8, 9, 10]. Static DAC experiments explore equilibrium material properties along an isotherm or an isobar [1]. Dynamic material properties can be explored with shock compression [2, 3], probing single states on the Hugoniot, or with quasi-isentropic compression [4, 5, 6, 7, 8, 9, 10]. In the case of shocks, pressures variation typically occurs on a sub-nanosecond time scale or faster [11]. Previous quasi-isentropic techniques have yielded pressure ramps on the 10-100 nanosecond time-scale for samples that are several hundred microns thick [4, 5, 6, 7]. In order to understand kinetic effects at high temperatures and high pressures, we need to span a large dynamic range (strain rates, relaxation times, etc.) as well as control the thermodynamic path that the material experiences. Compression rates, for instance, need to bridge those of static experiments (seconds to hours) and those of the Z-accelerator (10 6 s -1 ) [4] or even laser ablation techniques (10 6 s -1 to 10 8 s -1 ) [7]. Here, we present a new technique that both extends the compression time to several

  20. Laser fusion implosion and plasma interaction experiments

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.

    1977-08-01

    Results related to the propagation, absorption and scattering of laser light by both spherical and planar targets are described. The absorption measurements indicate that for intensities of interest, inverse bremsstrahlung is not the dominant absorption mechanism. The laser light scattered by the plasma is polarization dependent and provides evidence that Brillouin scattering and resonance absorption are operative. Special diagnostics have been designed and experiments have been performed to elucidate the nature of these two processes. Implosion results on glass microshell targets filled with DT gas are also summarized. These experiments are for targets intentionally operated in the portion of parameter space characteristic of exploding pusher events. Experiments have been performed over a yield range from 0 to 10 9 neutrons per event. It is shown how this data can be normalized with a simple scaling law

  1. HF-laser program

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The HF laser is an attractive candidate driver for a large-system ICF scientific demonstration facility, for an ICF experimental power reactor and for a commercial laser--fusion power reactor. Previous accomplishments of the program have included demonstrations of high efficiency and high energy capability, efficient energy extraction from HF amplifiers, good beam quality and focusability, and short-pulse generation and amplification. In the reporting period, beam quality has been determined to be near-diffraction limited for a short pulsewidth (6 ns to 25 ns) oscillator-amplifier chain, suppression of amplified spontaneous emission has been demonstrated on an individual spectral line, high-pressure characteristics have been determined for the Phoenix I amplifier, and detailed comparisions between the kinetic code and experiments have been made. Details of two major upcoming experiments are also included. The first is energy extraction and beam quality measurements on the Phoenix I amplifier operating under saturated output power conditions. The second experiment, using a newly designed amplifier (Phoenix II), is designed to demonstrate the concept of angular-multiplexing: a pulse width-compression scheme

  2. A theory overview on the Compressed Baryonic Matter Experiment at FAIR

    International Nuclear Information System (INIS)

    Nahrgang, Marlene

    2014-01-01

    The Compressed Baryonic Matter (CBM) experiment at FAIR offers for the first time in heavy-ion physics the opportunity to investigate extremely baryon-dense strongly interacting matter with large data samples as a basis for high precision measurements. This will allow us to put theories at test, answer questions about the structure of the phase diagram of QCD and the transport properties of the medium. In this overview I will highlight some recent advances on several key questions, which will be addressed by the CBM experiment.

  3. Bayesian model calibration of computational models in velocimetry diagnosed dynamic compression experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hund, Lauren [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    Dynamic compression experiments are being performed on complicated materials using increasingly complex drivers. The data produced in these experiments are beginning to reach a regime where traditional analysis techniques break down; requiring the solution of an inverse problem. A common measurement in dynamic experiments is an interface velocity as a function of time, and often this functional output can be simulated using a hydrodynamics code. Bayesian model calibration is a statistical framework to estimate inputs into a computational model in the presence of multiple uncertainties, making it well suited to measurements of this type. In this article, we apply Bayesian model calibration to high pressure (250 GPa) ramp compression measurements in tantalum. We address several issues speci c to this calibration including the functional nature of the output as well as parameter and model discrepancy identi ability. Speci cally, we propose scaling the likelihood function by an e ective sample size rather than modeling the autocorrelation function to accommodate the functional output and propose sensitivity analyses using the notion of `modularization' to assess the impact of experiment-speci c nuisance input parameters on estimates of material properties. We conclude that the proposed Bayesian model calibration procedure results in simple, fast, and valid inferences on the equation of state parameters for tantalum.

  4. TILDA. Fast experiment control and data acquisition in collinear laser spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, Simon [Inst. fuer Kernphysik, TU Darmstadt (Germany); Inst. fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz (Germany); Collaboration: TRIGA-SPEC-Collaboration

    2016-07-01

    The TRIGA-Laser Data Acqusition (TILDA) is a custom development for the collinear laser spectroscopy (CLS) experiment TRIGA-Laser. Situated at the research reactor TRIGA Mainz, the TRIGA-Laser experiment benefits from the possibility to create short-lived nuclides by neutron-induced fission of a heavy actinide target, e.g. {sup 249}Cf. The beam-line is equipped with a radio-frequency cooler and buncher emitting bunches with lengths in the order of 500 ns to 10 μs, which allows a drastical reduction of the background in CLS. In order to benefit from this bunched beam structure a time resolved data acquisition system is essential. The real time computing in TILDA is realized by field programmable gate arrays (FPGAs), which are synchronized via the backplane of a PXI-crate. This gives the user a great flexibility in adapting to different measurement schemes. This flexibility in hardware must therefore be given in equivalent way to the user in software. Due to that, high level programming languages were chosen (Labview and Python) and TILDA will provide the user with a solid framework around it. TILDAs main features, specifications, programming schematics and status will be presented.

  5. Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Zhitao [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Banishev, Alexandr A.; Christensen, James; Dlott, Dana D. [School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N., E-mail: naresh.thadhani@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Zhou, Min [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

    2016-07-28

    The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

  6. Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

    International Nuclear Information System (INIS)

    Kang, Zhitao; Banishev, Alexandr A.; Christensen, James; Dlott, Dana D.; Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N.; Xiao, Pan; Zhou, Min

    2016-01-01

    The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

  7. Laser in caries treatment--patients' experiences and opinions.

    Science.gov (United States)

    Sarmadi, R; Hedman, E; Gabre, P

    2014-02-01

    The aim of this study was to obtain a deeper understanding of patient's experiences and perspectives after dental caries treatment with Er:YAG laser technology. Twelve patients aged 15-30 years who had undergone at least one laser caries excavation agreed to participate in an interview study. All the interviews were tape recorded and transcribed by a transcription agency. The transcribed texts were analysed using manifest and latent qualitative content analysis. The categories in this study were identified as choosing laser, understanding laser, encouraging dental care and my oral health. The motivation for laser treatment was described as dental fear in general, specific fear of needles or discomfort with the drill. The informants described the dentist's role as initiators of treatment and willing or unwilling facilitators. Laser treatment was described as safer and more carefully considered treatment. They felt generally safe with laser and were able to relax during the treatment. All interviewers described a positive impression of the laser, and words like 'up to date' and 'future-oriented' were used to describe laser. Laser treatment was considered less painful. The results indicate that patients find laser a feasible and convenient treatment option. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    . The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse......We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror...

  9. Laser-driven ICF experiments: Laboratory Report No. 223

    International Nuclear Information System (INIS)

    McCrory, R.L.

    1991-04-01

    Laser irradiation uniformity is a key issue and is treated in some detail. The basic irradiation uniformity requirements and practical ways of achieving these requirements are both discussed, along with two beam-smoothing techniques: induced spatial incoherence (ISI), and smoothing by spectral dispersion (SSD). Experiments to measure and control the irradiation uniformity are also highlighted. Following the discussion of irradiation uniformity, a brief review of coronal physics is given, including the basic physical processes and their experimental signatures, together with a summary of pertinent diagnostics and results from experiments. Methods of determining ablation rates and thermal transport are also described. The hydrodynamics of laser-driven targets must be fully understood on the basis of experiments. Results from implosion experiments, including a brief description of the diagnostics, are presented. Future experiments aimed at determining ignition scaling and demonstrating hydrodynamically equivalent physics applicable to high-gain designs

  10. Creep and cracking of concrete hinges: insight from centric and eccentric compression experiments.

    Science.gov (United States)

    Schlappal, Thomas; Schweigler, Michael; Gmainer, Susanne; Peyerl, Martin; Pichler, Bernhard

    2017-01-01

    Existing design guidelines for concrete hinges consider bending-induced tensile cracking, but the structural behavior is oversimplified to be time-independent. This is the motivation to study creep and bending-induced tensile cracking of initially monolithic concrete hinges systematically. Material tests on plain concrete specimens and structural tests on marginally reinforced concrete hinges are performed. The experiments characterize material and structural creep under centric compression as well as bending-induced tensile cracking and the interaction between creep and cracking of concrete hinges. As for the latter two aims, three nominally identical concrete hinges are subjected to short-term and to longer-term eccentric compression tests. Obtained material and structural creep functions referring to centric compression are found to be very similar. The structural creep activity under eccentric compression is significantly larger because of the interaction between creep and cracking, i.e. bending-induced cracks progressively open and propagate under sustained eccentric loading. As for concrete hinges in frame-like integral bridge construction, it is concluded (i) that realistic simulation of variable loads requires consideration of the here-studied time-dependent behavior and (ii) that permanent compressive normal forces shall be limited by 45% of the ultimate load carrying capacity, in order to avoid damage of concrete hinges under sustained loading.

  11. The Compressed Baryonic Matter Experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Heuser J.M.

    2011-04-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is being planned at the international research centre FAIR, under realization next to the GSI laboratory in Darmstadt, Germany. Its physics programme addresses the QCD phase diagram in the region of highest net baryon densities. Of particular interest are the expected first order phase transition from partonic to hadronic matter, ending in a critical point, and modifications of hadron properties in the dense medium as a signal of chiral symmetry restoration. Laid out as a fixed-target experiment at the synchrotrons SIS-100/SIS-300, providing magnetic bending power of 100 and 300 T/m, the CBM detector will record both proton-nucleus and nucleus-nucleus collisions at beam energies up to 45A GeV. Hadronic, leptonic and photonic observables have to be measured with large acceptance. The nuclear interaction rates will reach up to 10 MHz to measure extremely rare probes like charm near threshold. Two versions of the experiment are being studied, optimized for either electron-hadron or muon identification, combined with silicon detector based charged-particle tracking and micro-vertex detection. The research programme will start at SIS-100 with ion beams between 2 and 11A GeV, and protons up to energies of 29 GeV using the HADES detector and an initial configuration of the CBM experiment. The CBM physics requires the development of novel detector systems, trigger and data acquisition concepts as well as innovative real-time reconstruction techniques. Progress with feasibility studies of the experiment and the development of its detector systems are discussed.

  12. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  13. Flame kernel characterization of laser ignition of natural gas-air mixture in a constant volume combustion chamber

    Science.gov (United States)

    Srivastava, Dhananjay Kumar; Dharamshi, Kewal; Agarwal, Avinash Kumar

    2011-09-01

    In this paper, laser-induced ignition was investigated for compressed natural gas-air mixtures. Experiments were performed in a constant volume combustion chamber, which simulate end of the compression stroke conditions of a SI engine. This chamber simulates the engine combustion chamber conditions except turbulence of air-fuel mixture. It has four optical windows at diametrically opposite locations, which are used for laser ignition and optical diagnostics simultaneously. All experiments were conducted at 10 bar chamber pressure and 373 K chamber temperature. Initial stage of combustion phenomena was visualized by employing Shadowgraphy technique using a high speed CMOS camera. Flame kernel development of the combustible fuel-air mixture was investigated under different relative air-fuel ratios ( λ=1.2-1.7) and the images were interrogated for temporal propagation of flame front. Pressure-time history inside the combustion chamber was recorded and analyzed. This data is useful in characterizing the laser ignition of natural gas-air mixture and can be used in developing an appropriate laser ignition system for commercial use in SI engines.

  14. Shock physics with the nova laser for ICF applications. Revision 1

    International Nuclear Information System (INIS)

    Hammel, B.A.; Cauble, R.; Celliers, P.

    1995-01-01

    The physics of high pressure shocks plays a central role in Inertial Confinement Fusion (ICF). In indirect drive ICF, x-rays from a gold cavity (hohlraum) are used to ablatively drive a series of high pressure shocks into a spherical target (capsule). These shocks converge at the center, compressing the fuel and forming a hot dense core. The target performance, such as peak fuel density and temperature and neutron yield, depends critically on hock timing, and material compressibility. Accurate predictions of NIF target performance depends critically on shock timing and material compressibility. Current measurement techniques enable us to accurately determine shock timing in planar samples of abator material as a function of laser drive. Although this technique does not separately address uncertainties in material EOS and opacity, it does allow us to tune the laser drive until the desired shock timing is achieved. Experiments to directly address the EOS of D 2 ice are planned to further increase the margin for ignition in current target designs

  15. Recoil Experiments Using a Compressed Air Cannon

    Science.gov (United States)

    Taylor, Brett

    2006-01-01

    Ping-Pong vacuum cannons, potato guns, and compressed air cannons are popular and dramatic demonstrations for lecture and lab. Students enjoy them for the spectacle, but they can also be used effectively to teach physics. Recently we have used a student-built compressed air cannon as a laboratory activity to investigate impulse, conservation of…

  16. Opto-mechanical design of vacuum laser resonator for the OSQAR experiment

    Science.gov (United States)

    Hošek, Jan; Macúchová, Karolina; Nemcová, Šárka; Kunc, Štěpán.; Šulc, Miroslav

    2015-01-01

    This paper gives short overview of laser-based experiment OSQAR at CERN which is focused on search of axions and axion-like particles. The OSQAR experiment uses two experimental methods for axion search - measurement of the ultra-fine vacuum magnetic birefringence and a method based on the "Light shining through the wall" experiment. Because both experimental methods have reached its attainable limits of sensitivity we have focused on designing a vacuum laser resonator. The resonator will increase the number of convertible photons and their endurance time within the magnetic field. This paper presents an opto-mechanical design of a two component transportable vacuum laser resonator. Developed optical resonator mechanical design allows to be used as a 0.8 meter long prototype laser resonator for laboratory testing and after transportation and replacement of the mirrors it can be mounted on the LHC magnet in CERN to form a 20 meter long vacuum laser resonator.

  17. PHELIX - Petawatt high-energy laser for heavy ion experiments

    International Nuclear Information System (INIS)

    Backe, H.; Bock, R.; Caird, J.

    1998-12-01

    A high-power laser facility will be installed at the GSI heavy-ion accelerator. It will deliver laser pulses up to one kilojoule (with an option of a later upgrade to several kJ) at a pulse length of 1 - 10 nanoseconds (high-energy mode). In a high-intensity mode, laser pulses with a power of one petawatt (10 15 Watt) will be generated by chirped pulse amplification at a pulse length of typically 500 femtoseconds. Details of the laser system as well as time schedule and costs are given in Section B. In combination with the heavy-ion beams available at GSI - which will be further improved in intensity by the presently on-going upgrade program - a large number of unique experiments will become possible by the high-power laser facility described in this report. As outlined in Section A, novel research opportunities are expected in a wide range of basic-research topics spanning from the study of ion-matter interaction, through challenging new experiments in atomic, nuclear, and astrophysics, into the virgin field of relativistic plasma physics. Foreseeable topics in applied science are the development of new sources for highly charged ions and of X-ray lasers, new concepts for laser-based particle acceleration and the research in the field of inertial confinement fusion. (orig.)

  18. Compression of magnetized target in the magneto-inertial fusion

    Science.gov (United States)

    Kuzenov, V. V.

    2017-12-01

    This paper presents a mathematical model, numerical method and results of the computer analysis of the compression process and the energy transfer in the target plasma, used in magneto-inertial fusion. The computer simulation of the compression process of magnetized cylindrical target by high-power laser pulse is presented.

  19. Free-electron laser experiments in the microwave tokamak experiment

    International Nuclear Information System (INIS)

    Allen, S.L.; Brown, M.D.; Byers, J.A.; Casper, T.A.; Cohen, B.I.; Cohen, R.H.; Cummings, J.C.; Fenstermacher, M.E.; Foote, J.H.; Hooper, E.B.; Jong, R.A.; Langdon, A.B.; Lasinski, B.F.; Lasnier, C.J.; Matsuda, Y.; Meyer, W.H.; Moller, J.M.; Nexsen, W.E.; Rice, B.W.; Rognlien, T.D.; Smith, G.R.; Stallard, B.W.; Thomassen, K.I.; Throop, A.L.; Turner, W.C.; Wood, R.D.; Cook, D.R.; Makowski, M.A.; Oasa, K.; Ogawa, T.

    1990-08-01

    Microwave pulses have been injected from a free electron-laser (FEL) into the Microwave Tokamak Experiment (MTX) at up to 0.2 GW at 140 GHz in short pulses (10-ns duration) with O-mode polarization. The power transmitted through the plasma was measured in a first experimental study of high power pulse propagation in the plasma; no nonlinear effects were found at this power level. Calculations indicate that nonlinear effects may be found at the higher power densities expected in future experiments. 9 refs., 2 figs

  20. Analytical calculations of intense Gaussian laser beam propagating in plasmas with relativistic collision correction

    International Nuclear Information System (INIS)

    Wang Ying; Yuan Chengxun; Gao Ruilin; Zhou Zhongxiang

    2012-01-01

    Theoretical investigations of a Gaussian laser beam propagating in relativistic plasmas have been performed with the WKB method and complex eikonal function. We consider the relativistic nonlinearity induced by intense laser beam, and present the relativistically generalized forms of the plasma frequency and electron collision frequency in plasmas. The coupled differential equations describing the propagation variations of laser beam are derived and numerically solved. The obtained simulation results present the similar variation tendency with experiments. By changing the plasma density, we theoretically analyze the feasibility of using a plasmas slab of a fixed thickness to compress the laser beam-width and acquire the focused laser intensity. The present work complements the relativistic correction of the electron collision frequency with reasonable derivations, promotes the theoretical approaching to experiments and provides effective instructions to the practical laser-plasma interactions.

  1. Radiative processes in a laser-fusion plasma

    International Nuclear Information System (INIS)

    Campbell, P.M.; Kubis, J.J.; Mitrovich, D.

    1976-01-01

    Plasmas compressed and heated by an intense laser pulse offer promise for the ignition of propagating thermonuclear burn and, ultimately, for use in fusion reactors. It is evident theoretically that the emission and absorption of x-rays by the plasma has a significant effect on the dynamics of the laser compression process. In order to achieve densities high enough for efficient thermonuclear burn, the fusion pellet must be compressed along a low adiabat. This will not be possible if the compressed region of the pellet is significantly preheated by x-rays originating in the hot outer regions. A satisfactory model of compression hydrodynamics must, therefore, include a comprehensive treatment of radiation transport based on a non-LTE model of the plasma. The model must be valid for Fermi-Dirac statistics, since high compression along a low adiabat will, in general, produce degenerate electron distributions. This report is concerned with the plasma model and the corresponding radiation emission and absorption coefficients, including nonthermal processes which occur in the laser deposition region

  2. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrane, Shawn David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bolme, Cindy B [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Whitley, Von H [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, David S [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2010-01-01

    Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

  3. First laser-plasma interaction and hohlraum experiments on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Dewald, E L; Glenzer, S H; Landen, O L; Suter, L J; Jones, O S; Schein, J; Froula, D; Divol, L; Campbell, K; Schneider, M S; Holder, J; McDonald, J W; Niemann, C; Mackinnon, A J; Hammel, B A [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550 (United States)

    2005-12-15

    Recently the first laser-plasma interaction and hohlraum experiments have been performed at the National Ignition Facility (NIF) in support of indirect drive inertial confinement fusion designs. The effects of laser beam smoothing by spectral dispersion and polarization smoothing on the intense (2 x 10{sup 15} W cm{sup -2}) beam propagation in gas-filled tubes has been studied at up to 7 mm plasma scales as found in indirect drive gas filled ignition hohlraum designs. These experiments have shown the expected full propagation without filamentation and beam break up when using full laser smoothing. In addition, vacuum hohlraums have been irradiated with laser powers up to 6 TW, 1-9 ns pulse lengths and energies up to 17 kJ to activate several diagnostics, to study the hohlraum radiation temperature scaling with the laser power and hohlraum size, and to make contact with hohlraum experiments performed at the Nova and Omega laser facilities. Subsequently, novel long laser pulse hohlraum experiments have tested models of hohlraum plasma filling and long pulse hohlraum radiation production. The validity of the plasma filling assessment using in analytical models and radiation hydrodynamics calculations with the code LASNEX has been proven in these studies. The comparison of these results with modelling will be discussed.

  4. High-efficiency free-electron-laser experiments

    International Nuclear Information System (INIS)

    Boyer, K.; Brau, C.A.; Goldstein, J.C.; Hohla, K.L.; Newnam, B.E.; Stein, W.E.; Warren, R.W.; Winston, J.G.

    1983-01-01

    Experiments with a tapered-wiggler free-electron laser have demonstrated extraction of about 3% of the energy from the electron beam and measured the corresponding optical emission. These results are in excellent agreement with theory and represent an order-of-magnitude improvement over all previous results

  5. Laser-plasma interaction physics for shock ignition

    Directory of Open Access Journals (Sweden)

    Goyon C.

    2013-11-01

    Full Text Available In the shock ignition scheme, the ICF target is first compressed with a long (nanosecond pulse before creating a convergent shock with a short (∼100 ps pulse to ignite thermonuclear reactions. This short pulse is typically (∼2.1015–1016 W/cm2 above LPI (Laser Plasma Instabilities thresholds. The plasma is in a regime where the electron temperature is expected to be very high (2–4 keV and the laser coupling to the plasma is not well understood. Emulating LPI in the corona requires large and hot plasmas produced by high-energy lasers. We conducted experiments on the LIL (Ligne d'Integration Laser, 10 kJ at 3ω and the LULI2000 (0.4 kJ at 2ω facilities, to approach these conditions and study absorption and LPI produced by a high intensity beam in preformed plasmas. After introducing the main risks associated with the short pulse propagation, we present the latest experiment we conducted on LPI in relevant conditions for shock ignition.

  6. Advanced Receiver/Converter Experiments for Laser Wireless Power Transmission

    Science.gov (United States)

    Howell, Joe T.; ONeill, Mark; Fork, Richard

    2004-01-01

    For several years NASA Marshall Space Flight Center, UAH and ENTECH have been working on various aspects of space solar power systems. The current activity was just begun in January 2004 to further develop this new photovoltaic concentrator laser receiver/converter technology. During the next few months, an improved prototype will be designed, fabricated, and thoroughly tested under laser illumination. The final paper will describe the new concept, present its advantages over other laser receiver/converter approaches (including planar photovoltaic arrays), and provide the latest experiment results on prototype hardware (including the effects of laser irradiance level and cell temperature). With NASA's new human exploration plans to first return to the Moon, and then to proceed to Mars, the new photovoltaic concentrator laser receiver/converter technology could prove to be extremely useful in providing power to the landing sites and other phases of the missions. For example, to explore the scientifically interesting and likely resource-rich poles of the Moon (which may contain water) or the poles of Mars (which definitely contain water and carbon dioxide), laser power beaming could represent the simplest means of providing power to these regions, which receive little or no sunlight, making solar arrays useless there. In summary, the authors propose a paper on definition and experimental results of a novel photovoltaic concentrator approach for collecting and converting laser radiation to electrical power. The new advanced photovoltaic concentrator laser receiver/converter offers higher performance, lighter weight, and lower cost than competing concepts, and early experimental results are confirming the expected excellent Performance levels. After the small prototypes are successfully demonstrated, a larger array with even better performance is planned for the next phase experiments and demonstrations. Thereafter, a near-term flight experiment of the new technology

  7. Short Pulse Laser Applications Design

    International Nuclear Information System (INIS)

    Town, R.J.; Clark, D.S.; Kemp, A.J.; Lasinski, B.F.; Tabak, M.

    2008-01-01

    We are applying our recently developed, LDRD-funded computational simulation tool to optimize and develop applications of Fast Ignition (FI) for stockpile stewardship. This report summarizes the work performed during a one-year exploratory research LDRD to develop FI point designs for the National Ignition Facility (NIF). These results were sufficiently encouraging to propose successfully a strategic initiative LDRD to design and perform the definitive FI experiment on the NIF. Ignition experiments on the National Ignition Facility (NIF) will begin in 2010 using the central hot spot (CHS) approach, which relies on the simultaneous compression and ignition of a spherical fuel capsule. Unlike this approach, the fast ignition (FI) method separates fuel compression from the ignition phase. In the compression phase, a laser such as NIF is used to implode a shell either directly, or by x rays generated from the hohlraum wall, to form a compact dense (∼300 g/cm 3 ) fuel mass with an areal density of ∼3.0 g/cm 2 . To ignite such a fuel assembly requires depositing ∼20kJ into a ∼35 (micro)m spot delivered in a short time compared to the fuel disassembly time (∼20ps). This energy is delivered during the ignition phase by relativistic electrons generated by the interaction of an ultra-short high-intensity laser. The main advantages of FI over the CHS approach are higher gain, a lower ignition threshold, and a relaxation of the stringent symmetry requirements required by the CHS approach. There is worldwide interest in FI and its associated science. Major experimental facilities are being constructed which will enable 'proof of principle' tests of FI in integrated subignition experiments, most notably the OMEGA-EP facility at the University of Rochester's Laboratory of Laser Energetics and the FIREX facility at Osaka University in Japan. Also, scientists in the European Union have recently proposed the construction of a new FI facility, called HiPER, designed to

  8. Magnetic field compression using pinch-plasma

    International Nuclear Information System (INIS)

    Koyama, K.; Tanimoto, M.; Matsumoto, Y.; Veno, I.

    1987-01-01

    In a previous report, the method for ultra-high magnetic field compression by using the pinchplasma was discussed. It is summarized as follows. The experiment is performed with the Mather-type plasma focus device tau/sub 1/4/ = 2 μs, I=880 kA at V=20 kV). An initial DC magnetic field is fed by an electromagnet embedded in the inner electrode. The axial component of the magnetic field diverges from the maximum field of 1 kG on the surface of the inner electrode. The density profile deduced from a Mach-Zehnder interferogram with a 2-ns N/sub 2/-laser shows a density dip lasting for 30 ns along the axes. Using the measured density of 8 x 10/sup 18/ cm/sup -3/, the temperature of 1.5 keV and the pressure balance relation, the magnitude of the trapped magnetic field is estimated to be 1.0 MG. The magnitude of the compressed magnetic field is also measured by Faraday rotation in a single-mode quartz fiber and a magnetic pickup soil. A protective polyethylene tube (3-mm o.d.) is used along the central axis through the inner electrode and the discharge chamber. The peak value of the compressed field range from 150 to 190 kG. No signal of the magnetic field appears up to the instance of the maximum pinch

  9. Estimation of fracture conditions of ceramics by thermal shock with laser beams based on the maximum compressive stress criterion

    International Nuclear Information System (INIS)

    Akiyama, Shigeru; Amada, Shigeyasu.

    1992-01-01

    Structural ceramics are attracting attention in the development of space planes, aircraft and nuclear fusion reactors because they have excellent wear-resistant and heat-resistant characteristics. However, in some applications it is anticipated that they will be exposed to very-high-temperature environments of the order of thousands of degrees. Therefore, it is very important to investigate their thermal shock characteristics. In this report, the distributions of temperatures and thermal stresses of cylindrically shaped ceramics under irradiation by laser beams are discussed using the finite-element computer code (MARC) with arbitrary quadrilateral axisymmetric ring elements. The relationships between spot diameters of laser beams and maximum values of compressive thermal stresses are derived for various power densities. From these relationships, a critical fracture curve is obtained, and it is compared with the experimental results. (author)

  10. Counterpropagating Radiative Shock Experiments on the Orion Laser.

    Science.gov (United States)

    Suzuki-Vidal, F; Clayson, T; Stehlé, C; Swadling, G F; Foster, J M; Skidmore, J; Graham, P; Burdiak, G C; Lebedev, S V; Chaulagain, U; Singh, R L; Gumbrell, E T; Patankar, S; Spindloe, C; Larour, J; Kozlova, M; Rodriguez, R; Gil, J M; Espinosa, G; Velarde, P; Danson, C

    2017-08-04

    We present new experiments to study the formation of radiative shocks and the interaction between two counterpropagating radiative shocks. The experiments are performed at the Orion laser facility, which is used to drive shocks in xenon inside large aspect ratio gas cells. The collision between the two shocks and their respective radiative precursors, combined with the formation of inherently three-dimensional shocks, provides a novel platform particularly suited for the benchmarking of numerical codes. The dynamics of the shocks before and after the collision are investigated using point-projection x-ray backlighting while, simultaneously, the electron density in the radiative precursor was measured via optical laser interferometry. Modeling of the experiments using the 2D radiation hydrodynamic codes nym and petra shows very good agreement with the experimental results.

  11. New pellet compression schemes by indirect irradiation of REB and related preliminary experiments

    International Nuclear Information System (INIS)

    Sato, M.; Tazima, T.; Yonezu, H.

    1986-01-01

    Preliminary experiments on a proposed scheme for pellet compression is carried out with a Point Pinch Diode. A high current density of ion beam is observed, and its value corresponds to 13.5 kA/cm 2 from the anode to the cathode. (author)

  12. Gasoline surrogate modeling of gasoline ignition in a rapid compression machine and comparison to experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mehl, M; Kukkadapu, G; Kumar, K; Sarathy, S M; Pitz, W J; Sung, S J

    2011-09-15

    The use of gasoline in homogeneous charge compression ignition engines (HCCI) and in duel fuel diesel - gasoline engines, has increased the need to understand its compression ignition processes under engine-like conditions. These processes need to be studied under well-controlled conditions in order to quantify low temperature heat release and to provide fundamental validation data for chemical kinetic models. With this in mind, an experimental campaign has been undertaken in a rapid compression machine (RCM) to measure the ignition of gasoline mixtures over a wide range of compression temperatures and for different compression pressures. By measuring the pressure history during ignition, information on the first stage ignition (when observed) and second stage ignition are captured along with information on the phasing of the heat release. Heat release processes during ignition are important because gasoline is known to exhibit low temperature heat release, intermediate temperature heat release and high temperature heat release. In an HCCI engine, the occurrence of low-temperature and intermediate-temperature heat release can be exploited to obtain higher load operation and has become a topic of much interest for engine researchers. Consequently, it is important to understand these processes under well-controlled conditions. A four-component gasoline surrogate model (including n-heptane, iso-octane, toluene, and 2-pentene) has been developed to simulate real gasolines. An appropriate surrogate mixture of the four components has been developed to simulate the specific gasoline used in the RCM experiments. This chemical kinetic surrogate model was then used to simulate the RCM experimental results for real gasoline. The experimental and modeling results covered ultra-lean to stoichiometric mixtures, compressed temperatures of 640-950 K, and compression pressures of 20 and 40 bar. The agreement between the experiments and model is encouraging in terms of first

  13. Intrinsic Dynamics of Quantum-Dash Lasers

    KAUST Repository

    Chen, Cheng; Djie, Hery Susanto; Hwang, James C. M.; Koch, Thomas L.; Lester, Luke F.; Ooi, Boon S.; Wang, Yang

    2011-01-01

    Temperature-dependent intrinsic modulation response of InAs/InAlGaAs quantum-dash lasers was investigated by using pulse optical injection modulation to minimize the effects of parasitics and self-heating. Compared to typical quantum-well lasers, the quantum-dash lasers were found to have comparable differential gain but approximately twice the gain compression factor, probably due to carrier heating by free-carrier absorption, as opposed to stimulated transition. Therefore, the narrower modulation bandwidth of the quantum-dash lasers than that of quantum-well lasers was attributed to their higher gain compression factor. In addition, as expected, quantum-dash lasers with relatively long and uniform dashes exhibit higher temperature stability than quantum-well lasers. However, the lasers with relatively short and nonuniform dashes exhibit stronger temperature dependence, probably due to their higher surface-to-volume ratio and nonuniform dash sizes. © 2011 IEEE.

  14. Intrinsic Dynamics of Quantum-Dash Lasers

    KAUST Repository

    Chen, Cheng

    2011-10-01

    Temperature-dependent intrinsic modulation response of InAs/InAlGaAs quantum-dash lasers was investigated by using pulse optical injection modulation to minimize the effects of parasitics and self-heating. Compared to typical quantum-well lasers, the quantum-dash lasers were found to have comparable differential gain but approximately twice the gain compression factor, probably due to carrier heating by free-carrier absorption, as opposed to stimulated transition. Therefore, the narrower modulation bandwidth of the quantum-dash lasers than that of quantum-well lasers was attributed to their higher gain compression factor. In addition, as expected, quantum-dash lasers with relatively long and uniform dashes exhibit higher temperature stability than quantum-well lasers. However, the lasers with relatively short and nonuniform dashes exhibit stronger temperature dependence, probably due to their higher surface-to-volume ratio and nonuniform dash sizes. © 2011 IEEE.

  15. Study of suprathermal electron transport in solid or compressed matter for the fast-ignitor scheme

    International Nuclear Information System (INIS)

    Perez, F.

    2010-01-01

    The inertial confinement fusion (ICF) concept is widely studied nowadays. It consists in quickly compressing and heating a small spherical capsule filled with fuel, using extremely energetic lasers. Since approximately 15 years, the fast-ignition (FI) technique has been proposed to facilitate the fuel heating by adding a particle beam - electrons generated by an ultra-intense laser - at the exact moment when the capsule compression is at its maximum. This thesis constitutes an experimental study of these electron beams generated by picosecond-scale lasers. We present new results on the characteristics of these electrons after they are accelerated by the laser (energy, divergence, etc.) as well as their interaction with the matter they pass through. The experimental results are explained and reveal different aspects of these laser-accelerated fast electrons. Their analysis allowed for significant progress in understanding several mechanisms: how they are injected into solid matter, how to measure their divergence, and how they can be automatically collimated inside compressed matter. (author) [fr

  16. Ultrafast laser pump/x-ray probe experiments

    International Nuclear Information System (INIS)

    Larsson, J.; Judd, E.; Schuck, P.J.

    1997-01-01

    In an ongoing project aimed at probing solids using x-rays obtained at the ALS synchrotron with a sub-picosecond time resolution following interactions with a 100 fs laser pulse, the authors have successfully performed pump-probe experiments limited by the temporal duration of ALS-pulse. They observe a drop in the diffraction efficiency following laser heating. They can attribute this to a disordering of the crystal. Studies with higher temporal resolution are required to determine the mechanism. The authors have also incorporated a low-jitter streakcamera as a diagnostic for observing time-dependant x-ray diffraction. The streakcamera triggered by a photoconductive switch was operated at kHz repetition rates. Using UV-pulses, the authors obtain a temporal response of 2 ps when averaging 5000 laser pulses. They demonstrate the ability to detect monochromatized x-ray radiation from a bend-magnet with the streak camera by measuring the pulse duration of a x-ray pulse to 70 ps. In conclusion, the authors show a rapid disordering of an InSb crystal. The resolution was determined by the duration of the ALS pulse. They also demonstrate that they can detect x-ray radiation from a synchrotron source with a temporal resolution of 2ps, by using an ultrafast x-ray streak camera. Their set-up will allow them to pursue laser pump/x-ray probe experiments to monitor structural changes in materials with ultrafast time resolution

  17. Contour forming of metals by laser peening

    Science.gov (United States)

    Hackel, Lloyd; Harris, Fritz

    2002-01-01

    A method and apparatus are provided for forming shapes and contours in metal sections by generating laser induced compressive stress on the surface of the metal workpiece. The laser process can generate deep compressive stresses to shape even thick components without inducing unwanted tensile stress at the metal surface. The precision of the laser-induced stress enables exact prediction and subsequent contouring of parts. A light beam of 10 to 100 J/pulse is imaged to create an energy fluence of 60 to 200 J/cm.sup.2 on an absorptive layer applied over a metal surface. A tamping layer of water is flowed over the absorptive layer. The absorption of laser light causes a plasma to form and consequently creates a shock wave that induces a deep residual compressive stress into the metal. The metal responds to this residual stress by bending.

  18. Monte Carlo analysis of highly compressed fissile assemblies. Pt. 1

    International Nuclear Information System (INIS)

    Raspet, R.; Baird, G.E.

    1978-01-01

    Laserinduced fission of highly compressed bare fissionable spheres is analyzed using Monte Carlo techniques. The critical mass and critical radius as a function of density are calculated and the fission energy yield is calculated and compared with the input laser energy necessary to achieve compression to criticality. (orig.) [de

  19. Laser transmitter for Lidar In-Space Technology Experiment

    Science.gov (United States)

    Chang, John; Cimolino, Marc; Petros, Mulugeta

    1991-01-01

    The Lidar In-Space Technology Experiment (LITE) Laser Transmitter Module (LTM) flight laser optical architecture has been space qualified by extensive testing at the system, subsystem and component level. The projected system output performance has been verified using an optically and electrically similar breadboard version of the laser. Parasitic lasing was closely examined and completely suppressed after design changes were implemented and tested. Oscillator and amplifier type heads were separately tested to 150 million shots. Critical subassemblies have undergone environmental testing to Shuttle qualification levels. A superior three color anti-reflection coating was developed and tested for use on 14 surfaces after the final amplifier.

  20. Rugby and elliptical-shaped hohlraums experiments on the OMEGA laser facility

    Science.gov (United States)

    Tassin, Veronique; Monteil, Marie-Christine; Depierreux, Sylvie; Masson-Laborde, Paul-Edouard; Philippe, Franck; Seytor, Patricia; Fremerye, Pascale; Villette, Bruno

    2017-10-01

    We are pursuing on the OMEGA laser facility indirect drive implosions experiments in gas-filled rugby-shaped hohlraums in preparation for implosion plateforms on LMJ. The question of the precise wall shape of rugby hohlraum has been addressed as part of future megajoule-scale ignition designs. Calculations show that elliptical-shaped holhraum is more efficient than spherical-shaped hohlraum. There is less wall hydrodynamics and less absorption for the inner cone, provided a better control of time-dependent symmetry swings. In this context, we have conducted a series of experiments on the OMEGA laser facility. The goal of these experiments was therefore to characterize energetics with a complete set of laser-plasma interaction measurements and capsule implosion in gas-filled elliptical-shaped hohlraum with comparison with spherical-shaped hohlraum. Experiments results are discussed and compared to FCI2 radiation hydrodynamics simulations.

  1. Image compression for the silicon drift detectors in the ALICE experiment

    International Nuclear Information System (INIS)

    Werbrouck, A.; Tosello, F.; Rivetti, A.; Mazza, G.; De Remigis, P.; Cavagnino, D.; Alberici, G.

    2001-01-01

    We describe an algorithm for the zero suppression and data compression for the Silicon Drift Detectors (SDD) in the ALICE experiment. The algorithm operates on 10-bit linear data streams from the SDDs by applying a 10 bit to 8-bit non-linear compression followed by a data reduction based on a two-threshold discrimination and a two-dimensional analysis along both the drift time and the anodes. The proposed scheme allows for a better understanding of the neighborhoods of the SDD signal clusters, thus improving their reconstructability, and also provides a statistical monitoring of the background characteristics for each SDD anode. The entire algorithm is purely combinatorial and thus can be executed in pipeline, without additional clock cycles, during the SDD readout. The hardware coding together with the methods for the expansion to the original 10-bit values in the offline analysis and for the background monitoring are presented

  2. Advanced lasers for fusion applications

    International Nuclear Information System (INIS)

    Krupke, W.F.

    1978-11-01

    Projections indicate that MJ/MW laser systems, operating with efficiencies in escess of 1 percent, are required to drive laser fusion power reactors. Moreover, a premium in pellet performance is anticipated as the wavelength of the driver laser system is decreased. Short wavelength laser systems based on atomic selenium (lambda = 0.49μ), terbium molcular vapors (0.55μ), thulium doped dielectric solids (0.46μ), and on pulse compressions of KrF excimer laser radiaton (0.27μ) have been proposed and studied for this purpose. The technological scalability and efficiency of each of these systems is examined in this paper. All of these systems are projected to meet minimum systems requirements. Amont them, the pulse-compressed KrF system is projected to have the highest potential efficiency (6%) and the widest range of systems design options

  3. Commissioning and operating experience of compressed air system of a reprocessing plant (Paper No. 5.10)

    International Nuclear Information System (INIS)

    Nair, M.K.T.; Bajpai, D.D.; Mishra, A.K.; Kulkarni, H.B.; Raje, R.V.; Rajeshwar, S.

    1992-01-01

    Compressed air system is one of the most important utility systems, required in the continued operation of a radiochemical plant. Moisture and oil free compressed air is used in large scale for process control and process operations in reprocessing plants. Commissioning and operating experience of this system is described in detail, to indicate the importance of the system in the overall design and operation of such chemical plant. (author). 1 tab

  4. Theory and analysis of soft x-ray laser experiments

    International Nuclear Information System (INIS)

    Whitten, B.L.; Hazi, A.U.

    1985-10-01

    The atomic modeling of soft x-ray laser schemes presents a formidable challenge to the theorists - a challenge magnified by the recent successful experiments. A complex plasma environment with many ion species present must be simulated. Effects such as turbulence, time dependence, and radiation transport, which are very difficult to model accurately, may be important. We shall describe our efforts to model the recently demonstrated soft x-ray laser in collisionally pumped neon-like selenium, with emphasis on the ionization balance and excited state kinetics. The relative importance of various atomic processes, such as collisional excitation and dielectronic recombination, on the inversion kinetics will be demonstrated. We shall compare our models with experimental results and evaluate the success of this technique in predicting and analyzing the results of x-ray laser experiments. 22 refs., 5 figs., 3 tabs

  5. The Compressed Baryonic Matter experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Höhne Claudia

    2018-01-01

    Full Text Available The CBM experiment will investigate highly compressed baryonic matter created in A+A collisions at the new FAIR research center. With a beam energy range up to 11 AGeV for the heaviest nuclei at the SIS 100 accelerator, CBM will investigate the QCD phase diagram in the intermediate range, i.e. at moderate temperatures but high net-baryon densities. This intermediate range of the QCD phase diagram is of particular interest, because a first order phase transition ending in a critical point and possibly new highdensity phases of strongly interacting matter are expected. In this range of the QCD phase diagram only exploratory measurements have been performed so far. CBM, as a next generation, high-luminosity experiment, will substantially improve our knowledge of matter created in this region of the QCD phase diagram and characterize its properties by measuring rare probes such as multi-strange hyperons, dileptons or charm, but also with event-by-event fluctuations of conserved quantities, and collective flow of identified particles. The experimental preparations with special focus on hadronic observables and strangeness is presented in terms of detector development, feasibility studies and fast track reconstruction. Preparations are progressing well such that CBM will be ready with FAIR start. As quite some detectors are ready before, they will be used as upgrades or extensions of already running experiments allowing for a rich physics program prior to FAIR start.

  6. Laser fusion experiments, facilities and diagnostics at Lawrence Livermore Laboratory

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.

    1980-02-01

    The progress of the LLL Laser Fusion Program to achieve high gain thermonuclear micro-explosions is discussed. Many experiments have been successfully performed and diagnosed using the large complex, 10-beam, 30 TW Shiva laser system. A 400 kJ design of the 20-beam Nova laser has been completed. The construction of the first phase of this facility has begun. New diagnostic instruments are described which provide one with new and improved resolution, information on laser absorption and scattering, thermal energy flow, suprathermal electrons and their effects, and final fuel conditions. Measurements were made on the absorption and Brillouin scattering for target irradiations at both 1.064 μm and 532 nm. These measurements confirm the expected increased absorption and reduced scattering at the shorter wavelength. Implosion experiments have been performed which have produced final fuel densities over the range of 10x to 100x liquid DT density

  7. Laser cooled ion beams and strongly coupled plasmas for precision experiments

    International Nuclear Information System (INIS)

    Bussmann, Michael

    2008-01-01

    This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C 3+ ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged 24 Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)

  8. Conceptual design of a laser-plasma accelerator driven free-electron laser demonstration experiment

    Energy Technology Data Exchange (ETDEWEB)

    Seggebrock, Thorben

    2015-07-08

    Up to now, short-wavelength free-electron lasers (FEL) have been systems on the scale of hundreds of meters up to multiple kilometers. Due to the advancements in laser-plasma acceleration in the recent years, these accelerators have become a promising candidate for driving a fifth-generation synchrotron light source - a lab-scale free-electron laser. So far, demonstration experiments have been hindered by the broad energy spread typical for this type of accelerator. This thesis addresses the most important challenges of the conceptual design for a first lab-scale FEL demonstration experiment using analytical considerations as well as simulations. The broad energy spread reduces the FEL performance directly by weakening the microbunching and indirectly via chromatic emittance growth, caused by the focusing system. Both issues can be mitigated by decompressing the electron bunch in a magnetic chicane, resulting in a sorting by energies. This reduces the local energy spread as well as the local chromatic emittance growth and also lowers performance degradations caused by the short bunch length. Moreover, the energy dependent focus position leads to a focus motion within the bunch, which can be synchronized with the radiation pulse, maximizing the current density in the interaction region. This concept is termed chromatic focus matching. A comparison shows the advantages of the longitudinal decompression concept compared to the alternative approach of transverse dispersion. When using typical laser-plasma based electron bunches, coherent synchrotron radiation and space-charge contribute in equal measure to the emittance growth during decompression. It is shown that a chicane for this purpose must not be as weak and long as affordable to reduce coherent synchrotron radiation, but that an intermediate length is required. Furthermore, the interplay of the individual concepts and components is assessed in a start-to-end simulation, confirming the feasibility of the

  9. Conceptual design of a laser-plasma accelerator driven free-electron laser demonstration experiment

    International Nuclear Information System (INIS)

    Seggebrock, Thorben

    2015-01-01

    Up to now, short-wavelength free-electron lasers (FEL) have been systems on the scale of hundreds of meters up to multiple kilometers. Due to the advancements in laser-plasma acceleration in the recent years, these accelerators have become a promising candidate for driving a fifth-generation synchrotron light source - a lab-scale free-electron laser. So far, demonstration experiments have been hindered by the broad energy spread typical for this type of accelerator. This thesis addresses the most important challenges of the conceptual design for a first lab-scale FEL demonstration experiment using analytical considerations as well as simulations. The broad energy spread reduces the FEL performance directly by weakening the microbunching and indirectly via chromatic emittance growth, caused by the focusing system. Both issues can be mitigated by decompressing the electron bunch in a magnetic chicane, resulting in a sorting by energies. This reduces the local energy spread as well as the local chromatic emittance growth and also lowers performance degradations caused by the short bunch length. Moreover, the energy dependent focus position leads to a focus motion within the bunch, which can be synchronized with the radiation pulse, maximizing the current density in the interaction region. This concept is termed chromatic focus matching. A comparison shows the advantages of the longitudinal decompression concept compared to the alternative approach of transverse dispersion. When using typical laser-plasma based electron bunches, coherent synchrotron radiation and space-charge contribute in equal measure to the emittance growth during decompression. It is shown that a chicane for this purpose must not be as weak and long as affordable to reduce coherent synchrotron radiation, but that an intermediate length is required. Furthermore, the interplay of the individual concepts and components is assessed in a start-to-end simulation, confirming the feasibility of the

  10. Optimizing beam transport in rapidly compressing beams on the neutralized drift compression experiment – II

    Directory of Open Access Journals (Sweden)

    Anton D. Stepanov

    2018-03-01

    Full Text Available The Neutralized Drift Compression Experiment-II (NDCX-II is an induction linac that generates intense pulses of 1.2 MeV helium ions for heating matter to extreme conditions. Here, we present recent results on optimizing beam transport. The NDCX-II beamline includes a 1-m-long drift section downstream of the last transport solenoid, which is filled with charge-neutralizing plasma that enables rapid longitudinal compression of an intense ion beam against space-charge forces. The transport section on NDCX-II consists of 28 solenoids. Finding optimal field settings for a group of solenoids requires knowledge of the envelope parameters of the beam. Imaging the beam on the scintillator gives the radius of the beam, but the envelope angle is not measured directly. We demonstrate how the parameters of the beam envelope (radius, envelop angle, and emittance can be reconstructed from a series of images taken by varying the B-field strengths of a solenoid upstream of the scintillator. We use this technique to evaluate emittance at several points in the NDCX-II beamline and for optimizing the trajectory of the beam at the entry of the plasma-filled drift section. Keywords: Charged-particle beams, Induction accelerators, Beam dynamics, Beam emittance, Ion beam diagnostics, PACS Codes: 41.75.-i, 41.85.Ja, 52.59.Sa, 52.59.Wd, 29.27.Eg

  11. Identification marking by means of laser peening

    Science.gov (United States)

    Hackel, Lloyd A.; Dane, C. Brent; Harris, Fritz

    2002-01-01

    The invention is a method and apparatus for marking components by inducing a shock wave on the surface that results in an indented (strained) layer and a residual compressive stress in the surface layer. One embodiment of the laser peenmarking system rapidly imprints, with single laser pulses, a complete identification code or three-dimensional pattern and leaves the surface in a state of deep residual compressive stress. A state of compressive stress in parts made of metal or other materials is highly desirable to make them resistant to fatigue failure and stress corrosion cracking. This process employs a laser peening system and beam spatial modulation hardware or imaging technology that can be setup to impress full three dimensional patterns into metal surfaces at the pulse rate of the laser, a rate that is at least an order of magnitude faster than competing marking technologies.

  12. The creation of radiation dominated plasmas using laboratory extreme ultra-violet lasers

    Science.gov (United States)

    Tallents, G. J.; Wilson, S.; West, A.; Aslanyan, V.; Lolley, J.; Rossall, A. K.

    2017-06-01

    Ionization in experiments where solid targets are irradiated by high irradiance extreme ultra-violet (EUV) lasers is examined. Free electron degeneracy effects on ionization in the presence of a high EUV flux of radiation is shown to be important. Overlap of the physics of such plasmas with plasma material under compression in indirect inertial fusion is explored. The design of the focusing optics needed to achieve high irradiance (up to 1014 Wcm-2) using an EUV capillary laser is presented.

  13. High speed photography diagnostics in laser-plasma interaction experiments

    International Nuclear Information System (INIS)

    Andre, M.L.

    1988-01-01

    The authors report on their effort in the development of techniques involved in laser-plasma experiments. This includes not only laser technology but also diagnostics studies and targets design and fabrication. Among the different kind of diagnostics currently used are high speed streak cameras, fast oscilloscopes and detectors sensitive in the i.r., visible, the u.v. region and the x-rays. In this presentation the authors describe the three high power lasers which are still in operation (P 102, OctAL and PHEBUS) and the main diagnostics used to characterize the plasma

  14. A review of low density porous materials used in laser plasma experiments

    Science.gov (United States)

    Nagai, Keiji; Musgrave, Christopher S. A.; Nazarov, Wigen

    2018-03-01

    This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.

  15. Inertial fusion program in Japan and ignition experiment facility by laser

    International Nuclear Information System (INIS)

    Nakai, S.

    1989-01-01

    The recent progress in laser fusion research is remarkable with respect to obtaining the high density and high temperature plasma which produces thermonuclear neutrons of 10 13 per shot (pellet gain of 0.2%) and to the understanding of implosion physics. Data bases for laser fusion have been accumulated and technologies for advanced experiments have been developed, both of which enable us to make the reserarch step toward the fusion ignition experiment and the achievement of the breakeven condition, which is estimated to be possible with a 100 kJ blue laser. The demonstration of high gain pellets requires laser energy in the range MJ in blue light. The design studies of the MJ laser are continue in the framework of the solid state laser at ILE. The design studies on the commercial reactor of ICF have proceeded and several conceptual designs have been proposed. These designs utilize a liquid metal first wall and blanket which enable long life for commercial use. As a consequence, the ICF reactor has technically a high feasibility for commercial application. (orig.)

  16. Monochromatic x-ray radiography of laser-driven spherical targets using high-energy, picoseconds LFEX laser

    Science.gov (United States)

    Sawada, Hiroshi; Fujioka, S.; Lee, S.; Arikawa, Y.; Shigemori, K.; Nagatomo, H.; Nishimura, H.; Sunahara, A.; Theobald, W.; Perez, F.; Patel, P. K.; Beg, F. N.

    2015-11-01

    Formation of a high density fusion fuel is essential in both conventional and advanced Inertial Confinement Fusion (ICF) schemes for the self-sustaining fusion process. In cone-guided Fast Ignition (FI), a metal cone is attached to a spherical target to maintain the path for the injection of an intense short-pulse ignition laser from blow-off plasma created when nanoseconds compression lasers drive the target. We have measured a temporal evolution of a compressed deuterated carbon (CD) sphere using 4.5 keV K-alpha radiography with the Kilo-Joule, picosecond LFEX laser at the Institute of Laser Engineering. A 200 μm CD sphere attached to the tip of a Au cone was directly driven by 9 Gekko XII beams with 300 J/beam in a 1.3 ns Gaussian pulse. The LFEX laser irradiated on a Ti foil to generate 4.51 Ti K-alpha x-ray. By varying the delay between the compression and backlighter lasers, the measured radiograph images show an increase of the areal density of the imploded target. The detail of the quantitative analyses to infer the areal density and comparisons to hydrodynamics simulations will be presented. This work was performed with the support and under the auspices of the NIFS Collaboration Research program (NIFS13KUGK072). H.S. was supported by the UNR's International Activities Grant program.

  17. Laser-plasma interactions for fast ignition

    Science.gov (United States)

    Kemp, A. J.; Fiuza, F.; Debayle, A.; Johzaki, T.; Mori, W. B.; Patel, P. K.; Sentoku, Y.; Silva, L. O.

    2014-05-01

    In the electron-driven fast-ignition (FI) approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser-plasma interactions (LPI) relevant to FI. Increases in computational and modelling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modelling approaches and configurations are addressed, providing an overview of the modelling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale FI problem.

  18. Construction and characterization of a laser-driven proton beamline at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Busold, Simon

    2014-05-15

    The thesis includes the first experiments with the new 100 TW laser beamline of the PHELIX laser facility at GSI Darmstadt to drive a TNSA (Target Normal Sheath Acceleration) proton source at GSI's Z6 experimental area. At consecutive stages a pulsed solenoid has been applied for beam transport and energy selection via chromatic focusing, as well as a radiofrequency cavity for energy compression of the bunch. This novel laser-driven proton beamline, representing a central experiment of the German national LIGHT collaboration (Laser Ion Generation, Handling and Transport), has been used to create collimated, intense proton bunches at 10 MeV with 2.7% energy spread from the laser-driven source. Also, the feasibility of phase focusing experiments with this setup has been shown and simulations predict peak currents of 10{sup 10} protons/ns at this energy level. Furthermore, first quantitative measurements on the spectral properties of the also present co-moving electrons from such a proton source could be performed and their influence on the protons within the solenoid observed. Finally, permanent magnetic quadrupoles as an alternative first ion collimation system have been investigated experimentally.

  19. A 158 fs 5.3 nJ fiber-laser system at 1 mu m using photonic bandgap fibers for dispersion control and pulse compression

    DEFF Research Database (Denmark)

    Nielsen, C.K.; Jespersen, Kim Giessmann; Keiding, S.R.

    2006-01-01

    We demonstrate a 158 fs 5.3 nJ mode-locked laser system based on a fiber oscillator, fiber amplifier and fiber compressor. Dispersion compensation in the fiber oscillator was obtained with a solid-core photonic bandgap (SC-PBG) fiber spliced to standard fibers, and external compression is obtained...... with a hollow-core photonic bandgap (HC-PBG) fiber....

  20. Status of the TRIGA-LASER experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gorges, C., E-mail: chgorges@uni-mainz.de; Kaufmann, S., E-mail: s.kaufmann@uni-mainz.de [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Geppert, Ch. [Johannes Gutenberg-Universität Mainz, Institut für Kernchemie (Germany); Krämer, J. [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Sánchez, R. [GSI Helmholtzzentrum für Schwerionenforschung (Germany); Nörtershäuser, W. [Technische Universität Darmstadt, Institut für Kernphysik (Germany)

    2017-11-15

    We report on the newly developed control system called TRITON and the new data acquisition called TILDA as well as on improved isotope shift measurements of the isotopes {sup 40,42,44,48}Ca in the 4s 2S1/2 → 4p 2P3/2 (D2) transition at the TRIGA-LASER experiment in Mainz using collinear laser spectroscopy. Well known isotope shift measurements in the 4s 2S1/2 → 4p 2P1/2 (D1) transition act as calibration points to reduce the uncertainties in the D2-line to provide reference values for the determination of nuclear charge radii and quadrupole moments of neutron rich calcium isotopes at COLLAPS.

  1. The x-ray laser coherence experiments in neon-like yttrium

    International Nuclear Information System (INIS)

    Shimkaveg, G.M.; Carter, M.R.; Walling, R.S.; Ticehurst, J.M.; Koch, J.A.; Mrowka, S.; Trebes, J.E.; MacGowan, B.J.; Da Silva, L.B.; Matthews, D.L.; London, R.A.; Stewart, R.E.

    1992-01-01

    We present recent results from neon-like x-ray laser experiments conducted at the Nova laser's Two-Beam Facility. This begins a series of experiments aimed at the characterization and control of the degree of spatial coherece in our soft x-ray laser beams, important to planned applications areas susch as microscopy and holography. New instrumentation developed for this effort include a fully time-resolved coherence diagnostic (which records a multiple-slit diffraction pattern) and wide-angle extreme ultraviolet spectrographs and beam divergence cameras. We present new measurements of beam profiles and gain, as well as spatial coherence data such as time-resolved multi-slit diffraction patterns. This new time-resolved coherence data exhibit aperture functions which increase in size during the time of the lasing. Also, some preliminary data is given from the first ''double-foil'' experiments, involving two x-ray amplifiers spatially separated by 29 cm and shot sequentially, in an ''oscillator-amplifier'' configuration

  2. Laser cooled ion beams and strongly coupled plasmas for precision experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bussmann, Michael

    2008-03-17

    This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C{sup 3+} ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged {sup 24}Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)

  3. Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification; Etude et realisation d'un laser a colorant femtoseconde fonctionnant a differentes longueurs d'onde. Compression et amplification d'impulsions ultrabreves

    Energy Technology Data Exchange (ETDEWEB)

    Georges, Patrick

    1989-12-21

    685 nm et inferieures a 50 fs entre 775 nm et 800 nm ont ete produites pour la premiere fois par verouillage de modes passif. Un regime de fonctionnement particulier du laser a ete observe et analyse en termes de solitons optiques. Les impulsions dans le proche infrarouge nous ont permis d'etudier la cinetique de la saturation de l'absorption dans des semi-conducteurs du type multipuits quantiques GaAs/AIGaAs. Afin de realiser des experiences de spectroscopie resolue dans le temps avec des impulsions encore plus breves, nous avons etudie un systeme de compression d'impulsions suivi d'une amplification pour augmenter leur energie. Des impulsions de 20 fs avec une energie de 10 microjoules (puissance crete: 0,5 GW) ont ete obtenues a faible cadence (10 Hz) et des impulsions de 16 fs avec une energie de 0,6 microjoules ont ete produites a haut taux de repetition (11 kHz) en utilisant un laser a vapeur de cuivre. Ces impulsions ont ete utilisees pour etudier la cinetique de la saturation de l'absorption dans un colorant organique: le Vert de Malachite. (auteur)

  4. Experience With Laser Safety In The USA--A Review

    Science.gov (United States)

    Sliney, David H.

    1986-10-01

    Following several research programs in the 1960's aimed at studying the adverse biological effects of lasers and other optical radiation sources, laser occupational exposure limits were set and general safety standards were developed. Today, the experience from laser accidents and the development of new lasers and new applications have altered the format of the exposure limits and the safety procedures. It is critically important to distinguish between different biological injury mechanisms. The biological effects of ultraviolet radiation upon the skin and eye are additive over a period of at least one workday, and require different safety procedures. The scattered UV irradiance from excimer lasers may be quite hazardous, depending upon wavelength and action spectra. Since laser technology is young, the exposure of an individual in natural sunlight must be studied to evaluate the potential for chronic effects. The safety measures necessary in the use of lasers depend upon a hazard evaluation. The appropriate control measures and alternate means of enclosure, baffling, and operational control measures are presented. Present laser safety standards are explained briefly. Eye protective techniques and eyewear are considered for a variety of sources. The optical properties of enclosure materials are also discussed.

  5. Diagnostics developments and applications for laser fusion experiments

    International Nuclear Information System (INIS)

    Coleman, L.W.

    1977-01-01

    Some diagnostics techniques applied to current laser fusion target experiments are reviewed. Specifically, holographic interferometry of target plasmas, coded aperture imaging of thermonuclear alpha-particles and neutron energy spectrum measurements are discussed

  6. Measurements of the toroidal plasma rotation velocity in TFTR major-radius compression experiments with auxiliary neutral beam heating

    International Nuclear Information System (INIS)

    Bitter, M.; Wong, K.L.; Scott, S.; Hsuan, H.; Grek, B.; Johnson, D.; Tait, G.

    1990-01-01

    The time history of the central toroidal plasma rotation velocity in Tokamak Fusion Test Reactor (TFTR) experiments [Phys. Rev. Lett. 55, 2587 (1985)] with auxiliary heating by neutral deuterium beam injection and major-radius compression has been measured from the Doppler shift of the emitted Ti XXI Kα line radiation. The experiments were conducted for neutral beam powers in the range 2.1--3.8 MW and line-averaged densities in the range 1.8--3.0x10 19 m -2 . The observed rotation velocity increase during compression is consistent with theoretical estimates

  7. Pump-probe experiments in atoms involving laser and synchrotron radiation: an overview

    International Nuclear Information System (INIS)

    Wuilleumier, F J; Meyer, M

    2006-01-01

    The combined use of laser and synchrotron radiations for atomic photoionization studies started in the early 1980s. The strong potential of these pump-probe experiments to gain information on excited atomic states is illustrated through some exemplary studies. The first series of experiments carried out with the early synchrotron sources, from 1960 to about 1995, are reviewed, including photoionization of unpolarized and polarized excited atoms, and time-resolved laser-synchrotron studies. With the most advanced generation of synchrotron sources, a whole new class of pump-probe experiments benefiting from the high brightness of the new synchrotron beams has been developed since 1996. A detailed review of these studies as well as possible future applications of pump-probe experiments using third generation synchrotron sources and free electron lasers is presented. (topical review)

  8. Photoacoustic tweezers with a pulsed laser: theory and experiments

    International Nuclear Information System (INIS)

    Zharov, V P; Malinsky, T V; Kurten, R C

    2005-01-01

    A novel noninvasive optical technique for manipulating particles and cells is presented that utilizes laser-generated forces in an absorbing medium surrounding the particles or cells. In this technique, a laser pulse creates near-object acoustic waves, which during interaction with the objects lead to then being moved or trapped. The main optical schemes are considered, and a theory is presented for this new optical tool, namely photoacoustic (PA) tweezer with pulsed laser. The magnitudes of forces acting on polystyrene particles suspended in water were estimated as a function of the particles' properties for circular and ring geometries of the laser beam. Results of our preliminary experiments demonstrated proof that the manipulation, trapping and even rotation of cells is possible with PA tweezers

  9. Compressed baryonic matter experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Jürgen Eschke

    2012-02-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is being planned at the Facility for Antiproton and Ion Research (FAIR, under realization next to the GSI laboratory in Darmstadt, Germany. Its physics programme addresses the QCD phase diagram in the region of highest net baryon densities. Of particular interest are the expected first order phase transition from partonic to hadronic matter, ending in a critical point, and modifcations of hadron properties in the dense medium as a signal of chiral symmetry restoration. Laid out as a fixed-target experiment at the synchrotrons SIS-100/SIS-300, providing magnetic bending power of 100 and 300 T/Fm, the CBM detector will record both proton-nucleus and nucleus-nucleus collisions at beam energies up to 45 AGeV. Hadronic, leptonic and photonic observables will be measured in a large acceptance. The nuclear interaction rates will reach up to 10 MHz to measure extremely rare probes like charm near threshold. This requires the development of novel detector systems, trigger and data acquisition concepts as well as in- novative real-time reconstruction techniques. A key observable of the physics program is a precise measurement of lowmass vector mesons and charmonium in their leptonic decay channel. In CBM, electrons will be identified using a gaseous RICH detector combined with several TRD detectors positioned after a system of silicon tracking stations which are located inside a magnetic dipole field. The concept of the RICH detector, results on R & D as well as feasibility studies and invariant mass distributions of charmonium will be discussed.

  10. Crack propagation behavior of TiN coatings by laser thermal shock experiments

    International Nuclear Information System (INIS)

    Choi, Youngkue; Jeon, Seol; Jeon, Min-seok; Shin, Hyun-Gyoo; Chun, Ho Hwan; Lee, Youn-seoung; Lee, Heesoo

    2012-01-01

    Highlights: ► The crack propagation behavior of TiN coating after laser thermal shock experiment was observed by using FIB and TEM. ► Intercolumnar cracks between TiN columnar grains were predominant cracking mode after laser thermal shock. ► Cracks were propagated from the coating surface to the substrate at low laser pulse energy and cracks were originated at coating-substrate interface at high laser pulse energy. ► The cracks from the interface spread out transversely through the weak region of the columnar grains by repetitive laser shock. - Abstract: The crack propagation behavior of TiN coatings, deposited onto 304 stainless steel substrates by arc ion plating technique, related to a laser thermal shock experiment has been investigated using focused ion beam (FIB) and transmission electron microscopy (TEM). The ablated regions of TiN coatings by laser ablation system have been investigated under various conditions of pulse energies and number of laser pulses. The intercolumnar cracks were predominant cracking mode following laser thermal shock tests and the cracks initiated at coating surface and propagated in a direction perpendicular to the substrate under low loads conditions. Over and above those cracks, the cracks originated from coating-substrate interface began to appear with increasing laser pulse energy. The cracks from the interface also spread out transversely through the weak region of the columnar grains by repetitive laser shock.

  11. Tomography of laser fusion plasmas

    International Nuclear Information System (INIS)

    Ceglio, N.M.

    1977-01-01

    Experimental programs exist in a number of laboratories throughout the world to test the feasibility of using powerful laser systems to drive the implosion of hydrogen isotope fuel to thermonuclear burn conditions. In a typical experiment multiple laser beams are focused onto a glass microshell (typically 50 μm to 200 μm diameter) filled with an equimolar D-T gas mixture. X-ray and particle emissions from the target provide important information about the hydrodynamic implosion of the glass shell and the associated compression and heating of the D-T fuel. Standard diagnostics for imaging such emissions are the grazing incidence reflection (GIR) x-ray microscope and the pinhole camera. Recently, a particular coded imaging technique, Zone Plate Coded Imaging (ZPCI), has been successfully used for x-ray and particle microscopy of laser fusion plasmas. ZPCI is highly attractive for investigating laser produced plasmas because it possesses a tomographic capability not shared by either the GIR or pinhole imaging techniques. This presentation provides a brief discussion of the tomographic potential of ZPCI. In addition, the first tomographic x-ray images (tomographic resolution approximately 74 μm) of a laser produced plasma are presented

  12. Hydrodynamic instability experiments on the HIPER laser facility at the Institute of Laser Engineering, Osaka University

    International Nuclear Information System (INIS)

    Shigemori, K.; Azechi, H.; Fujioka, S.

    2003-01-01

    We present recent results on the hydrodynamic instability experiments on the HIPER (High Intensity Plasma Experimental Research) laser facility at ILE, Osaka University. We measured the Rayleigh-Taylor growth rate on the HIPER laser. Also measured were all parameters that determine the RT growth rate. We focused on the measurements of the ablation density of laser-irradiated targets, which had not been experimentally measured. The experimental results were compared with calculations with one dimensional simulation coupled with Fokker-Planck equation for electron transport. (author)

  13. Characterization of a plasma produced using a high power laser with a gas puff target for x-ray laser experiments

    International Nuclear Information System (INIS)

    Fiedorowicz, H.; Bartnik, A.; Gac, K.; Parys, P.; Szczurek, M.; Tyl, J.

    1995-01-01

    A high temperature, high density plasma can be produced by using a nanosecond, high-power laser with a gas puff target. The gas puff target is formed by puffing a small amount of gas from a high-pressure reservoir through a nozzle into a vacuum chamber. In this paper we present the gas puff target specially designed for x-ray laser experiments. The solenoid valve with the nozzle in the form of a slit 0.3-mm wide and up to 40-mm long, allows to form an elongated gas puff suitable for the creation of an x-ray laser active medium by its perpendicular irradiation with the use of a laser beam focused to a line. Preliminary results of the experiments on the laser irradiation of the gas puff targets, produced by the new valve, show that hot plasma suitable for x-ray lasers is created

  14. Optical synchronization of a free-electron laser with femtosecond precision

    International Nuclear Information System (INIS)

    Loehl, F.

    2009-09-01

    High-gain free-electron lasers (FELs) are capable of generating sub-10 fs long light pulses. In order to take full advantage of these extremely short light pulses in time-resolved experiments, synchronization with a so far unprecedented timing accuracy is required. Within this thesis, an optical synchronization system providing sub-10 fs stability has been developed and was implemented at the ultra-violet and soft X-ray free-electron laser FLASH at DESY, Hamburg. The system uses a mode-locked laser as a timing reference. The laser pulses are distributed via length stabilized optical fiber-links to the remote locations. A key feature of the system is a bunch arrival-time monitor detecting the electron bunch arrival-time with an unrivaled resolution of 6 fs. A feedback system based on the arrival-time monitor was established, improving the arrival-time fluctuations from 200 fs in the unstabilized case to 25 fs with active feedback. In order to achieve the high peak current of several thousand amperes required for the FEL process, the electron bunches are longitudinally compressed in two magnetic chicanes. A second feedback system was developed stabilizing the bunch compression process based on measurements of diffraction radiation. The combination of both feedback systems improves the stability of the FEL radiation significantly. (orig.)

  15. Optical synchronization of a free-electron laser with femtosecond precision

    Energy Technology Data Exchange (ETDEWEB)

    Loehl, F.

    2009-09-15

    High-gain free-electron lasers (FELs) are capable of generating sub-10 fs long light pulses. In order to take full advantage of these extremely short light pulses in time-resolved experiments, synchronization with a so far unprecedented timing accuracy is required. Within this thesis, an optical synchronization system providing sub-10 fs stability has been developed and was implemented at the ultra-violet and soft X-ray free-electron laser FLASH at DESY, Hamburg. The system uses a mode-locked laser as a timing reference. The laser pulses are distributed via length stabilized optical fiber-links to the remote locations. A key feature of the system is a bunch arrival-time monitor detecting the electron bunch arrival-time with an unrivaled resolution of 6 fs. A feedback system based on the arrival-time monitor was established, improving the arrival-time fluctuations from 200 fs in the unstabilized case to 25 fs with active feedback. In order to achieve the high peak current of several thousand amperes required for the FEL process, the electron bunches are longitudinally compressed in two magnetic chicanes. A second feedback system was developed stabilizing the bunch compression process based on measurements of diffraction radiation. The combination of both feedback systems improves the stability of the FEL radiation significantly. (orig.)

  16. Bayesian model calibration of ramp compression experiments on Z

    Science.gov (United States)

    Brown, Justin; Hund, Lauren

    2017-06-01

    Bayesian model calibration (BMC) is a statistical framework to estimate inputs for a computational model in the presence of multiple uncertainties, making it well suited to dynamic experiments which must be coupled with numerical simulations to interpret the results. Often, dynamic experiments are diagnosed using velocimetry and this output can be modeled using a hydrocode. Several calibration issues unique to this type of scenario including the functional nature of the output, uncertainty of nuisance parameters within the simulation, and model discrepancy identifiability are addressed, and a novel BMC process is proposed. As a proof of concept, we examine experiments conducted on Sandia National Laboratories' Z-machine which ramp compressed tantalum to peak stresses of 250 GPa. The proposed BMC framework is used to calibrate the cold curve of Ta (with uncertainty), and we conclude that the procedure results in simple, fast, and valid inferences. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Dynamic fragmentation of laser shock-melted tin: experiment and modelling

    Energy Technology Data Exchange (ETDEWEB)

    De Resseguier, T. [CNRS ENSMA, Lab Combust and Deton, F-86961 Futuroscope (France); Signor, L.; Dragon, A. [CNRS ENSMA, Mecan and Phys Mat Lab, F-86961 Futuroscope (France); Signor, L.; Roy, G. [CEA Valduc, 21 - Is-sur-Tille (France)

    2010-07-01

    Dynamic fragmentation of shock-loaded metals is an issue of considerable importance for both basic science and a variety of technological applications, such as pyrotechnics or inertial confinement fusion, the latter involving high energy laser irradiation of thin metallic shells. Whereas spall fracture in solid materials has been extensively studied for many years, little data can be found yet about the evolution of this phenomenon after partial or full melting on compression or on release. Here, we present an investigation of dynamic fragmentation in laser shock-melted tin, from the 'micro-spall' process (ejection of a cloud of fine droplets) occurring upon reflection of the compressive pulse from the target free surface, to the late rupture observed in the un-spalled melted layer (leading to the formation of larger spherical fragments). Experimental results consist of time-resolved velocity measurements and post-shock observations of recovered targets and fragments. They provide original information regarding the loss of tensile strength associated with melting, the cavitation mechanism likely to occur in the melted metal, the sizes of the subsequent fragments and their ejection velocities. A theoretical description based on an energetic approach adapted to the case of a liquid metal is implemented as a failure criterion in a one-dimensional hydro-code including a multi-phase equation of state for tin. The resulting predictions of the micro-spall process are compared with experimental data. In particular, the use of a new experimental technique to quantify the fragment size distributions leads to a much better agreement with theory than previously reported. Finally, a complementary approach focused on cavitation is proposed to evaluate the role of this phenomenon in the fragmentation of the melted metal. (authors)

  18. Density ratios in compressions driven by radiation pressure

    International Nuclear Information System (INIS)

    Lee, S.

    1988-01-01

    It has been suggested that in the cannonball scheme of laser compression the pellet may be considered to be compressed by the 'brute force' of the radiation pressure. For such a radiation-driven compression, an energy balance method is applied to give an equation fixing the radius compression ratio K which is a key parameter for such intense compressions. A shock model is used to yield specific results. For a square-pulse driving power compressing a spherical pellet with a specific heat ratio of 5/3, a density compression ratio Γ of 27 is computed. Double (stepped) pulsing with linearly rising power enhances Γ to 1750. The value of Γ is not dependent on the absolute magnitude of the piston power, as long as this is large enough. Further enhancement of compression by multiple (stepped) pulsing becomes obvious. The enhanced compression increases the energy gain factor G for a 100 μm DT pellet driven by radiation power of 10 16 W from 6 for a square pulse power with 0.5 MJ absorbed energy to 90 for a double (stepped) linearly rising pulse with absorbed energy of 0.4 MJ assuming perfect coupling efficiency. (author)

  19. Assessment of eddy current effects on compression experiments in the TFTR tokamak

    International Nuclear Information System (INIS)

    Wong, K.L.; Park, W.

    1986-05-01

    The eddy current induced on the TFTR vacuum vessel during compression experiments is estimated based on a cylindrical model. It produces an error magnetic field that generates magnetic islands at the rational magnetic surfaces. The widths of these islands are calculated and found to have some effect on electron energy confinement. However, resistive MHD simulation results indicate that the island formation process can be slowed down by plasma rotation

  20. A unified modeling approach for physical experiment design and optimization in laser driven inertial confinement fusion

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haiyan [Mechatronics Engineering School of Guangdong University of Technology, Guangzhou 510006 (China); Huang, Yunbao, E-mail: Huangyblhy@gmail.com [Mechatronics Engineering School of Guangdong University of Technology, Guangzhou 510006 (China); Jiang, Shaoen, E-mail: Jiangshn@vip.sina.com [Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Jing, Longfei, E-mail: scmyking_2008@163.com [Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Tianxuan, Huang; Ding, Yongkun [Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-11-15

    Highlights: • A unified modeling approach for physical experiment design is presented. • Any laser facility can be flexibly defined and included with two scripts. • Complex targets and laser beams can be parametrically modeled for optimization. • Automatically mapping of laser beam energy facilitates targets shape optimization. - Abstract: Physical experiment design and optimization is very essential for laser driven inertial confinement fusion due to the high cost of each shot. However, only limited experiments with simple structure or shape on several laser facilities can be designed and evaluated in available codes, and targets are usually defined by programming, which may lead to it difficult for complex shape target design and optimization on arbitrary laser facilities. A unified modeling approach for physical experiment design and optimization on any laser facilities is presented in this paper. Its core idea includes: (1) any laser facility can be flexibly defined and included with two scripts, (2) complex shape targets and laser beams can be parametrically modeled based on features, (3) an automatically mapping scheme of laser beam energy onto discrete mesh elements of targets enable targets or laser beams be optimized without any additional interactive modeling or programming, and (4) significant computation algorithms are additionally presented to efficiently evaluate radiation symmetry on the target. Finally, examples are demonstrated to validate the significance of such unified modeling approach for physical experiments design and optimization in laser driven inertial confinement fusion.

  1. A laser plasma beatwave accelerator experiment

    International Nuclear Information System (INIS)

    Ebrahim, N.A.

    1987-03-01

    An experiment to test the laser plasma beatware accelerator concept is outlined. A heuristic estimate of the relevant experimental parameters is obtained from fluid theory and considerations of wave-particle interactions. Acceleration of 10 MeV electrons to approximately 70 MeV over a plasma length of 3 cm appears to be feasible. This corresponds to an accelerating gradient of approximately 2.5 GeV/m

  2. Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression

    Science.gov (United States)

    Guerette, Michael; Ackerson, Michael R.; Thomas, Jay; Yuan, Fenglin; Bruce Watson, E.; Walker, David; Huang, Liping

    2015-10-01

    Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young’s modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.

  3. Computational modeling of direct-drive fusion pellets and KrF-driven foil experiments

    International Nuclear Information System (INIS)

    Gardner, J.H.; Schmitt, A.J.; Dahlburg, J.P.; Pawley, C.J.; Bodner, S.E.; Obenschain, S.P.; Serlin, V.; Aglitskiy, Y.

    1998-01-01

    FAST is a radiation transport hydrodynamics code that simulates laser matter interactions of relevance to direct-drive laser fusion target design. FAST solves the Euler equations of compressible flow using the Flux-Corrected Transport finite volume method. The advection algorithm provides accurate computation of flows from nearly incompressible vortical flows to those that are highly compressible and dominated by strong pressure and density gradients. In this paper we describe the numerical techniques and physics packages. FAST has also been benchmarked with Nike laser facility experiments in which linearly perturbed, low adiabat planar plastic targets are ablatively accelerated to velocities approaching 10 7 cm/s. Over a range of perturbation wavelengths, the code results agree with the measured Rayleigh endash Taylor growth from the linear through the deeply nonlinear regimes. FAST has been applied to the two-dimensional spherical simulation design to provide surface finish and laser bandwidth tolerances for a promising new direct-drive pellet that uses a foam ablator

  4. Laser experiments explore the hidden sector

    International Nuclear Information System (INIS)

    Ahlers, M.

    2007-11-01

    Recently, the laser experiments BMV and GammeV, searching for light shining through walls, have published data and calculated new limits on the allowed masses and couplings for axion-like particles. In this note we point out that these experiments can serve to constrain a much wider variety of hidden-sector particles such as, e.g., minicharged particles and hidden-sector photons. The new experiments improve the existing bounds from the older BFRT experiment by a factor of two. Moreover, we use the new PVLAS constraints on a possible rotation and ellipticity of light after it has passed through a strong magnetic field to constrain pure minicharged particle models. For masses -7 times the electron electric charge. This is the best laboratory bound and comparable to bounds inferred from the energy spectrum of the cosmic microwave background. (orig.)

  5. Laser targets: introduction

    International Nuclear Information System (INIS)

    Rosen, M.D.

    1985-01-01

    The laser target design group was engaged in three main tasks in 1984: (1) analyzing Novette implosion and hohlraum-scaling data, (2) planning for the first experiments on Nova, and (3) designing laboratory x-ray laser targets and experiments. The Novette implosion and hohlraum scaling data are mostly classified and are therefore not discussed in detail here. The authors achieved average final/initial pusher pr ratios of about 50, some 3 times higher than the value achieved in the best Shiva shots. These pr values imply a fuel compression to 100 times liquid density, although this figure and other aspects of the experiments are subject to further interpretation because of detailed questions of target symmetry and stability. Their main long-term goal for Nova is to produce a so-called hydrodynamically equivalent target (HET) - that is, a target whose hydrodynamic behavior (implosion velocity, convergence ratio, symmetry and stability requirements, etc.) is very much like that of a high-gain target, but one that is scaled down in size to match the energy available from Nova and is too small to achieve enough hot-spot pr to ignite the cold, near-Fermi-degenerate fuel around it. Their goal for Nova's first year is to do experiments that will teach them how to achieve the symmetry and stability conditions required by an HET

  6. Data formats design of laser irradiation experiments in view of data analysis

    International Nuclear Information System (INIS)

    Su Chunxiao; Yu Xiaoqi; Yang Cunbang; Guo Su; Chen Hongsu

    2002-01-01

    The designing rules of new data file formats of laser irradiation experiments are introduced. Object-oriented programs are designed in studying experimental data of the laser facilities. The new format data files are combinations of the experiment data and diagnostic configuration data, which are applied in data processing and analysis. The edit of diagnostic configuration data in data acquisition program is also described

  7. Numerical simulation of compressible multiphase flows with or without phase transition. Application to laser plasma interaction

    International Nuclear Information System (INIS)

    Perrier, V.

    2007-07-01

    This work deals with the modelling and simulation of compressible flows. A seven equations model is obtained by homogenizing the Euler system. Fluctuation terms are modeled as relaxation terms. When the relaxation terms tend to infinity, which means that the phases are well mixed, a five equations model is obtained via an asymptotic expansion. This five equations model is strictly hyperbolic, but nonconservative. The discretization of this model is obtained by an asymptotic expansion of a scheme for the seven equations model. The numerical method is implemented, validated on analytic cases, and compared with experiments in the case of multiphase shocks. We are then interested in the modelling of phase transition with two equations of state. Optimization of the mixture entropy leads to the fact that three zones can be separated: one in which the pure liquid is the most stable, one in which the pure gas is the most stable, and one in which a mixture with equality of temperature, pressure and chemical potentials is the most stable. Conditions are given on the coupling of the two equations of state for ensuring that the mixture equation of state is convex, and that the system is strictly hyperbolic. In order to take into account phase transition, a vaporization wave is introduced in the solution of the Riemann problem, that is modeled as a deflagration wave. It is then proved that the usual closure, the Chapman-Jouguet closure, is wrong in general, and a correct closure in the case when both fluids have a perfect gas equation of state. Last, the solution of the Riemann problem is implemented in a multiphase code, and validated on analytic cases. In the same code, models of laser release and thermal conduction are implemented to simulate laser ablation. The results are comparable to the ones obtained with scale laws. The last chapter, fully independent, is concerned with correctors in stochastic homogenization in the case of heavy tails process. (author)

  8. Preliminary design of experiment high power density laser beam interaction with plasmas and development of a cold cathode electron beam laser amplifier

    International Nuclear Information System (INIS)

    Mosavi, R.K.; Kohanzadeh, Y.; Taherzadeh, M.; Vaziri, A.

    1976-01-01

    This experiment is designed to produce plasma by carbon dioxide pulsed laser, to measure plasma parameters and to study the interaction of the produced plasma with intense laser beams. The objectives of this experiment are the following: 1. To set up a TEA CO 2 laser oscillator and a cold cathode electron beam laser amplifier together as a system, to produce high energy optical pulses of short duration. 2. To achieve laser intensities of 10 11 watt/cm 2 or more at solid targets of polyethylene (C 2 H 4 )n, lithium hydride (LiH), and lithium deuteride in order to produce high temperature plasmas. 3. To design and develop diagnostic methods for studies of laser-induced plasmas. 4. To develop a high power CO 2 laser amplifier for the purpose of upgrading the optical energy delivered to the targets

  9. Spatially and temporally resolved x-ray emission from imploding laser fusion targets

    International Nuclear Information System (INIS)

    Attwood, D.T.; Coleman, L.W.; Boyle, M.J.; Phillion, D.W.; Swain, J.E.; Manes, K.R.; Larsen, J.T.

    1976-09-01

    The Livermore 15 psec x-ray streak camera has been used in conjunction with 6 μm diameter pinholes to record well resolved implosion histories of DT filled laser fusion targets. The space-time compression data provide clearly identified implosion velocities, typically 3 x 10 7 cm/sec for two-sided clamshell irradiation of a 70 μm/sup D/, .5 μm wall DT filled glass microshell. Single-sided irradiation results show hydrodynamic convergence at the target center, followed by an asymmetric but two-sided target disassembly. These experiments were performed at the two arm Janus Laser facility, which typically delivered a total of 0.4 TW in a 70 psec pulse for these experiments

  10. Gamma-neutron activation experiments using laser wakefield accelerators

    International Nuclear Information System (INIS)

    Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.

    2001-01-01

    Gamma-neutron activation experiments have been performed with relativistic electron beams produced by a laser wakefield accelerator. The electron beams were produced by tightly focusing (spot diameter ≅6 μm) a high power (up to 10 TW), ultra-short (≥50 fs) laser beam from a high repetition rate (10 Hz) Ti:sapphire (0.8 μm) laser system, onto a high density (>10 19 cm -3 ) pulsed gasjet of length ≅1.5 mm. Nuclear activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Measured γ-ray and neutron yields are also found to be in reasonable agreement with simulations using a Monte Carlo transport code

  11. CO2 laser interaction with magnetically confined plasmas. Annual report

    International Nuclear Information System (INIS)

    Vlases, G.C.; Pietrzyk, Z.A.

    1977-08-01

    The experimental program involves two basic experimental configurations termed the slow (or steady) solenoid, and the fast solenoid. In the former, the field is essentially steady during the experiment lifetime, the gas (plasma) remains in contact with the wall, and all the heating is done by the laser. In the fast solenoid, the field rises on a timescale comparable to the laser pulse length, removing the plasma from the wall, and contributing to the plasma energy content via compression work. In the slow solenoid, preionization is generally not used, and the laser both creates the plasma and heats it. In the fast solenoid, the preionization technique is relatively critical as it must create conditions leading to a true particle minimum on axis in order to insure favorable refraction of the laser beam (''trapping''). Substantial progress has been made in both experiments this year, particularly with respect to diagnostic capabilities. In addition, the theoretical effort has expanded considerably. Highlights of this year's program are listed and details are contained in the balance of the report

  12. Numerical simulation of compressible multiphase flows with or without phase transition. Application to laser plasma interaction; Modelisation et simulation d'ecoulements multiphasiques compressibles avec ou sans changement de phase. Application a l'interaction laser-plasma

    Energy Technology Data Exchange (ETDEWEB)

    Perrier, V

    2007-07-15

    This work deals with the modelling and simulation of compressible flows. A seven equations model is obtained by homogenizing the Euler system. Fluctuation terms are modeled as relaxation terms. When the relaxation terms tend to infinity, which means that the phases are well mixed, a five equations model is obtained via an asymptotic expansion. This five equations model is strictly hyperbolic, but nonconservative. The discretization of this model is obtained by an asymptotic expansion of a scheme for the seven equations model. The numerical method is implemented, validated on analytic cases, and compared with experiments in the case of multiphase shocks. We are then interested in the modelling of phase transition with two equations of state. Optimization of the mixture entropy leads to the fact that three zones can be separated: one in which the pure liquid is the most stable, one in which the pure gas is the most stable, and one in which a mixture with equality of temperature, pressure and chemical potentials is the most stable. Conditions are given on the coupling of the two equations of state for ensuring that the mixture equation of state is convex, and that the system is strictly hyperbolic. In order to take into account phase transition, a vaporization wave is introduced in the solution of the Riemann problem, that is modeled as a deflagration wave. It is then proved that the usual closure, the Chapman-Jouguet closure, is wrong in general, and a correct closure in the case when both fluids have a perfect gas equation of state. Last, the solution of the Riemann problem is implemented in a multiphase code, and validated on analytic cases. In the same code, models of laser release and thermal conduction are implemented to simulate laser ablation. The results are comparable to the ones obtained with scale laws. The last chapter, fully independent, is concerned with correctors in stochastic homogenization in the case of heavy tails process. (author)

  13. Multimode seeded Richtmyer-Meshkov mixing in a convergent, compressible, miscible plasma system

    International Nuclear Information System (INIS)

    Lanier, N.E.; Barnes, Cris W.; Batha, S.H.; Day, R.D.; Magelssen, G.R.; Scott, J.M.; Dunne, A.M.; Parker, K.W.; Rothman, S.D.

    2003-01-01

    Richtmyer-Meshkov (RM) mixing seeded by multimode initial surface perturbations in a convergent, compressible, miscible plasma system is measured on the OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system. A strong shock (Mach 12-20), created by 50 laser beams, is used to accelerate impulsively a thin aluminum shell into a lower density foam. As the system converges, both interfaces of the aluminum are RM unstable and undergo mixing. Standard x-ray radiographic techniques are employed to survey accurately the zero-order hydrodynamics, the average radius and overall width, of the marker. LASNEX [G. B. Zimmerman et al., Comments on Plasma Physics 2, 51 (1975)] simulations are consistent with the zero-order behavior of initially smooth markers. In experiments with smooth aluminum markers, the measured marker width shortly after shock passage behaves incompressibly and thickens due to Bell-Plesset effects. At high convergence (>4), the marker begins to compress as the rebounding shock passes back through the marker. When an initial multimode perturbation is introduced to the outer surface of the marker, the measured marker width is observed to increase by 10-15 μm, and is substantially smaller than as-shot simulations using RAGE [R. M. Baltrusaitis et al., Phys. Fluids 8, 2471 (1996)] would predict

  14. Developing the Physics Basis of Fast Ignition Experiments at Future Large Fusion-class lasers

    International Nuclear Information System (INIS)

    Mackinnon, A J; Key, M H; Hatchett, S; MacPhee, A G; Foord, M; Tabak, M; Town, R J; Patel, P K

    2008-01-01

    The Fast Ignition (FI) concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy (IFE) reactors. FI differs from conventional 'central hot spot' (CHS) target ignition by using one driver (laser, heavy ion beam or Z-pinch) to create a dense fuel and a separate ultra-short, ultra-intense laser beam to ignite the dense core. FI targets can burn with ∼ 3X lower density fuel than CHS targets, resulting in (all other things being equal) lower required compression energy, relaxed drive symmetry, relaxed target smoothness tolerances, and, importantly, higher gain. The short, intense ignition pulse that drives this process interacts with extremely high energy density plasmas; the physics that controls this interaction is only now becoming accessible in the lab, and is still not well understood. The attraction of obtaining higher gains in smaller facilities has led to a worldwide explosion of effort in the studies of FI. In particular, two new US facilities to be completed in 2009/2010, OMEGA/OMEGA EP and NIF-ARC (as well as others overseas) will include FI investigations as part of their program. These new facilities will be able to approach FI conditions much more closely than heretofore using direct drive (dd) for OMEGA/OMEGA EP and indirect drive (id) for NIF-ARC. This LDRD has provided the physics basis for the development of the detailed design for integrated Fast ignition experiments on these facilities on the 2010/2011 timescale. A strategic initiative LDRD has now been formed to carry out integrated experiments using NIF ARC beams to heat a full scale FI assembled core by the end of 2010

  15. Multi-scale modelling for HEDP experiments on Orion

    Science.gov (United States)

    Sircombe, N. J.; Ramsay, M. G.; Hughes, S. J.; Hoarty, D. J.

    2016-05-01

    The Orion laser at AWE couples high energy long-pulse lasers with high intensity short-pulses, allowing material to be compressed beyond solid density and heated isochorically. This experimental capability has been demonstrated as a platform for conducting High Energy Density Physics material properties experiments. A clear understanding of the physics in experiments at this scale, combined with a robust, flexible and predictive modelling capability, is an important step towards more complex experimental platforms and ICF schemes which rely on high power lasers to achieve ignition. These experiments present a significant modelling challenge, the system is characterised by hydrodynamic effects over nanoseconds, driven by long-pulse lasers or the pre-pulse of the petawatt beams, and fast electron generation, transport, and heating effects over picoseconds, driven by short-pulse high intensity lasers. We describe the approach taken at AWE; to integrate a number of codes which capture the detailed physics for each spatial and temporal scale. Simulations of the heating of buried aluminium microdot targets are discussed and we consider the role such tools can play in understanding the impact of changes to the laser parameters, such as frequency and pre-pulse, as well as understanding effects which are difficult to observe experimentally.

  16. Advanced plasma flow simulations of cathodic-arc and ferroelectric plasma sources for neutralized drift compression experiments

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2008-07-01

    Full Text Available Large-space-scale and long-time-scale plasma flow simulations are executed in order to study the spatial and temporal evolution of plasma parameters for two types of plasma sources used in the neutralized drift compression experiment (NDCX. The results help assess the charge neutralization conditions for ion beam compression experiments and can be employed in more sophisticated simulations, which previously neglected the dynamical evolution of the plasma. Three-dimensional simulations of a filtered cathodic-arc plasma source show the coupling efficiency of the plasma flow from the source to the drift region depends on geometrical factors. The nonuniform magnetic topology complicates the well-known general analytical considerations for evaluating guiding-center drifts, and particle-in-cell simulations provide a self-consistent evaluation of the physics in an otherwise challenging scenario. Plasma flow profiles of a ferroelectric plasma source demonstrate that the densities required for longitudinal compression experiments involving ion beams are provided over the drift length, and are in good agreement with measurements. Simulations involving azimuthally asymmetric plasma creation conditions show that symmetric profiles are nevertheless achieved at the time of peak on-axis plasma density. Also, the ferroelectric plasma expands upstream on the thermal expansion time scale, and therefore avoids the possibility of penetration into the acceleration gap and transport sections, where partial neutralization would increase the beam emittance. Future experiments on NDCX will investigate the transverse focusing of an axially compressing intense charge bunch to a sub-mm spot size with coincident focal planes using a strong final-focus solenoid. In order to fill a multi-tesla solenoid with the necessary high-density plasma for beam charge neutralization, the simulations predict that supersonically injected plasma from the low-field region will penetrate and

  17. Laser heated solenoid proof-of-concept experiment (PCX) facility

    International Nuclear Information System (INIS)

    DeHart, T.E.; Zumdieck, J.F.; Hoffman, A.L.; Lowenthal, D.D.; Crawford, E.A.; Parry, B.

    1977-01-01

    The total facility, including laser, magnet, focusing optics, instrumentation and control, its design problems, and its current performance are discussed. Preliminary results from plasma heating experiments are discussed

  18. Experimental study of fast electron transport and of the propagation of shock waves generated by laser in the framework of inertial fusion

    International Nuclear Information System (INIS)

    Sakaki, T.

    2016-01-01

    This document presents 3 experiments carried out within the framework of inertial fusion. The first experiment was devoted to the study of fast electron beam transport in a compressed target. The implosion of the target with a cylindrical geometry was carried out with the GEKKO XII laser facility (ILE Osaka, Japan). The fast electron beam was generated by the LFEX laser (∼10"1"9 W/cm"2) and its propagation through the compressed cylinder was observed with several X-ray diagnostics. This experiment showed the guiding effect of the electron beam resulting from self-generated magnetic fields. Furthermore, the results of this experiment were in good agreement with numerical simulations. Two other experiments were performed to study the propagation of strong shock waves created by lasers in a plasma. They were carried out with different laser systems. In the first experiment with the Gekko XII laser, we observed the creation and the propagation of two successive shock waves in an ablation plasma in CH and Be. The objective of characterizing the amplification of a transmitted shock by the collision of two counter-propagating shocks has been partially realized. The comparison of the experimental results with the hydrodynamic simulations enabled us to confirm an amplification of the shock by a factor 2 in pressure in the condition of this experiment. The shot with a Be target allowed the development and validation of the diagnostic method of X-ray radiography for shock wave propagation. The second experiment was performed with PHELIX GSI laser (Darmstadt, Germany). The purpose of this experiment was to study the generation of strong shocks. They were applied to study the equation of state of carbon in the WDM state. The condition of pressure and density for the carbon were obtained by deducing the pressure and the velocity of the shock wave chronometric diagnostics employed in this experiment. In this experiment, diamond was at the metallic liquid phase with a pressure

  19. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation.

    Science.gov (United States)

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  20. Proton- and x-ray beams generated by ultra-fast CO2 lasers for medical applications

    Science.gov (United States)

    Pogorelsky, Igor; Polyanskiy, Mikhail; Yakimenko, Vitaly; Ben-Zvi, Ilan; Shkolnikov, Peter; Najmudin, Zulfikar; Palmer, Charlotte A. J.; Dover, Nicholas P.; Oliva, Piernicola; Carpinelli, Massimo

    2011-05-01

    Recent progress in using picosecond CO2 lasers for Thomson scattering and ion-acceleration experiments underlines their potentials for enabling secondary radiation- and particle- sources. These experiments capitalize on certain advantages of long-wavelength CO2 lasers, such as higher number of photons per energy unit, and favorable scaling of the electrons' ponderomotive energy and critical plasma density. The high-flux x-ray bursts produced by Thomson scattering of the CO2 laser off a counter-propagating electron beam enabled high-contrast, time-resolved imaging of biological objects in the picosecond time frame. In different experiments, the laser, focused on a hydrogen jet, generated monoenergetic proton beams via the radiation-pressure mechanism. The strong power-scaling of this regime promises realization of proton beams suitable for laser-driven proton cancer therapy after upgrading the CO2 laser to sub-PW peak power. This planned improvement includes optimizing the 10-μm ultra-short pulse generation, assuring higher amplification in the CO2 gas under combined isotopic- and power-broadening effects, and shortening the postamplification pulse to a few laser cycles (150-200 fs) via chirping and compression. These developments will move us closer to practical applications of ultra-fast CO2 lasers in medicine and other areas.

  1. Alvar engine. An engine with variable compression ratio. Experiments and tests

    Energy Technology Data Exchange (ETDEWEB)

    Erlandsson, Olof

    1998-09-01

    This report is focused on tests with Variable Compression Ratio (VCR) engines, according to the Alvar engine principle. Variable compression ratio means an engine design where it is possible to change the nominal compression ratio. The purpose is to increase the fuel efficiency at part load by increasing the compression ratio. At maximum load, and maybe supercharging with for example turbocharger, it is not possible to keep a high compression ratio because of the knock phenomena. Knock is a shock wave caused by self-ignition of the fuel-air mix. If knock occurs, the engine will be exposed to a destructive load. Because of the reasons mentioned it would be an advantage if it would be possible to change the compression ratio continuously when the load changes. The Alvar engine provides a solution for variable compression ratio based on well-known engine components. This paper provides information about efficiency and emission characteristics from tests with two Alvar engines. Results from tests with a phase shift mechanism (for automatic compression ratio control) for the Alvar engine are also reviewed Examination paper. 5 refs, 23 figs, 2 tabs, 5 appendices

  2. Effects of tensile and compressive in-plane stress fields on adhesion in laser induced delamination experiments

    NARCIS (Netherlands)

    Fedorov, A.; Vellinga, W. P.; De Hosson, J. Th. M.

    2008-01-01

    In this work, the adhesion of a polymer coating on steel substrate subjected to uniaxial tensile plastic deformations was studied with the laser induced delamination technique. A decrease in the practical work of adhesion has been measured as the deformation of the substrate progressed. Moreover, it

  3. Simple model of the indirect compression of targets under conditions close to the national ignition facility at an energy of 1.5 MJ

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, V. B., E-mail: rozanov@sci.lebedev.ru; Vergunova, G. A., E-mail: verg@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2015-11-15

    The possibility of the analysis and interpretation of the reported experiments with the megajoule National Ignition Facility (NIF) laser on the compression of capsules in indirect-irradiation targets by means of the one-dimensional RADIAN program in the spherical geometry has been studied. The problem of the energy balance in a target and the determination of the laser energy that should be used in the spherical model of the target has been considered. The results of action of pulses differing in energy and time profile (“low-foot” and “high-foot” regimes) have been analyzed. The parameters of the compression of targets with a high-density carbon ablator have been obtained. The results of the simulations are in satisfactory agreement with the measurements and correspond to the range of the observed parameters. The set of compared results can be expanded, in particular, for a more detailed determination of the parameters of a target near the maximum compression of the capsule. The physical foundation of the possibility of using the one-dimensional description is the necessity of the closeness of the last stage of the compression of the capsule to a one-dimensional process. The one-dimensional simulation of the compression of the capsule can be useful in establishing the boundary behind which two-dimensional and three-dimensional simulation should be used.

  4. Intra-pulse Cavity Enhanced Measurements of Carbon Monoxide in a Rapid Compression Machine

    KAUST Repository

    Nasir, Ehson Fawad; Farooq, Aamir

    2018-01-01

    A laser absorption sensor for carbon monoxide concentration was developed for combustion studies in a rapid compression machine using a pulsed quantum cascade laser near 4.89 μm. Cavity enhancement reduced minimum detection limit down to 2.4 ppm

  5. Tunable solid-state laser technology for applications to scientific and technological experiments from space

    Science.gov (United States)

    Allario, F.; Taylor, L. V.

    1986-01-01

    Current plans for the Earth Observing System (EOS) include development of a lidar facility to conduct scientific experiments from a polar orbiting platforms. A recommended set of experiments were scoped, which includes techniques of atmospheric backscatter (Lidar), Differential Absorption Lidar (DIAL), altimetry, and retroranging. Preliminary assessments of the resources (power, weight, volume) required by the Eos Lidar Facility were conducted. A research program in tunable solid state laser technology was developed, which includes laser materials development, modeling and experiments on the physics of solid state laser materials, and development of solid state laser transmitters with a strong focus on Eos scientific investigations. Some of the system studies that were conducted which highlight the payoff of solid state laser technology for the Eos scientific investigations will be discussed. Additionally, a summary of some promising research results which have recently emerged from the research program will be presented.

  6. Monolithic all-PM femtosecond Yb-doped fiber laser using photonic bandgap fibers

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2009-01-01

    We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm.......We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm....

  7. High-power laser experiments to study collisionless shock generation

    Directory of Open Access Journals (Sweden)

    Sakawa Y.

    2013-11-01

    Full Text Available A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  8. TuFF3. Self-focusing in underdense ultraviolet laser-produced plasmas

    International Nuclear Information System (INIS)

    Tanaka, K.; Boswell, B.; Craxton, R.S.; Goldman, L.M.; Richardson, M.C.; Seka, W.; Short, R.W.; Soures, J.M.

    1984-01-01

    Ultraviolet laser-matter interaction processes are of considerable interest to laser fusion. Among these processes, filamentation (or self-focusing) is of particular importance, since it could prevent attainment of the illumination uniformity required for high target compression. In addition self-focusing may complicate the interpretation of target interaction experiments. Self-focusing has been studied experimentally by side-on x-ray pinhole camera photography and backscatter spectrometry. These results are compared with two-dimensional simulations using the hydro code SAGE, which is well suited to model thermal self-focusing (no ponderomotive forces are included in these simulations)

  9. Laser shock wave and its applications

    Science.gov (United States)

    Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

    2007-12-01

    The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

  10. Plasma production and heating by a laser TEA-CO2

    International Nuclear Information System (INIS)

    Goes, L.C.S.; Sudano, J.P.; Rodrigues, N.A.S.

    1987-01-01

    Preliminary experiments of plasma production and heating by laser irradiation of gases and solid targets have been performed with a laser TEA-CO 2 (1 MW, 80 ns, monomode), developed and built at the IEAv/Laser Laboratory. The laser beam was focused in the interior of a vacuum chamber (100 1) with a base pressure of 10 1 torr, and recolimated by a system of confocal lenses. The breakdown theresholds for nitrogen gas was investigated by varying the laser power, the neutral gas density and the focal lenght of the lenses. Plasma breakdown observed in the range of pressures between 100-720 torr was in good agreement with calculations of cascade ionization theory and classical absorption by inverse-Bremsstrahlung. The laser absorption was inferred by measuring the power transmitted in the presence and absence of plasma. The light emitted by the plasma was detected by a fast photo-diode, indicating that the plasma expansion phase lasted for several microseconds. These investigations have been applied in the development of plasma shutters for laser pulse compression. (author) [pt

  11. Using acoustic levitation in synchrotron based laser pump hard x-ray probe experiments

    Science.gov (United States)

    Hu, Bin; Lerch, Jason; Suthar, Kamlesh; Dichiara, Anthony

    Acoustic levitation provides a platform to trap and hold a small amount of material by using standing pressure waves without a container. The technique has a potential to be used for laser pump x-ray probe experiments; x-ray scattering and laser distortion from the container can be avoided, sample consumption can be minimized, and unwanted chemistry that may occur at the container interface can be avoided. The method has been used at synchrotron sources for studying protein and pharmaceutical solutions using x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). However, pump-probe experiments require homogeneously excited samples, smaller than the absorption depth of the material that must be held stably at the intersection of both the laser and x-ray beams. We discuss 1) the role of oscillations in acoustic levitation and the optimal acoustic trapping conditions for x-ray/laser experiments, 2) opportunities to automate acoustic levitation for fast sample loading and manipulation, and 3) our experimental results using SAXS to monitor laser induced thermal expansion in gold nanoparticles solution. We also performed Finite Element Analysis to optimize the trapping performance and stability of droplets ranging from 0.4 mm to 2 mm. Our early x-ray/laser demonstrated the potential of the technique for time-resolved X-ray science.

  12. Optimization of Error-Bounded Lossy Compression for Hard-to-Compress HPC Data

    Energy Technology Data Exchange (ETDEWEB)

    Di, Sheng; Cappello, Franck

    2018-01-01

    Since today’s scientific applications are producing vast amounts of data, compressing them before storage/transmission is critical. Results of existing compressors show two types of HPC data sets: highly compressible and hard to compress. In this work, we carefully design and optimize the error-bounded lossy compression for hard-tocompress scientific data. We propose an optimized algorithm that can adaptively partition the HPC data into best-fit consecutive segments each having mutually close data values, such that the compression condition can be optimized. Another significant contribution is the optimization of shifting offset such that the XOR-leading-zero length between two consecutive unpredictable data points can be maximized. We finally devise an adaptive method to select the best-fit compressor at runtime for maximizing the compression factor. We evaluate our solution using 13 benchmarks based on real-world scientific problems, and we compare it with 9 other state-of-the-art compressors. Experiments show that our compressor can always guarantee the compression errors within the user-specified error bounds. Most importantly, our optimization can improve the compression factor effectively, by up to 49% for hard-tocompress data sets with similar compression/decompression time cost.

  13. Laser plasma instability experiments with KrF lasers

    International Nuclear Information System (INIS)

    Weaver, J. L.; Karasik, M.; Serlin, V.; Obenschain, S.; Chan, L-Y.; Kehne, D.; Schmitt, A. J.; Colombant, D.; Velikovich, A.; Oh, J.; Lehmberg, R. H.; Afeyan, B.; Phillips, L.; Seely, J.; Brown, C.; Feldman, U.; Aglitskiy, Y.; Mostovych, A. N.; Holland, G.

    2007-01-01

    Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248 nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low-aspect-ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. The proposed KrF-laser-based Fusion Test Facility (FTF) would exploit this strategy to achieve significant fusion power (150 MW) with a rep-rate system that has a per pulse laser energy well below 1 MJ. Measurements of LPI using the Nike KrF laser are presented at and above intensities needed for the FTF (I∼2x10 15 W/cm 2 ). The results to date indicate that LPI is indeed suppressed. With overlapped beam intensity above the planar, single beam intensity threshold for the two-plasmon decay instability, no evidence of instability was observed via measurements of (3/2)ω o and (1/2)ω o harmonic emissions

  14. Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

    International Nuclear Information System (INIS)

    Peterson, R. R.; Lindman, E. L.; Delamater, N. D.; Magelssen, G. R.

    2000-01-01

    LASNEX computer code simulations have been performed for radiation symmetry experiments on the Nova laser with vacuum and gas-filled hohlraum targets [R. L. Kauffman et al., Phys. Plasmas 5, 1927 (1998)]. In previous experiments with unsmoothed laser beams, the symmetry was substantially shifted by deflection of the laser beams. In these experiments, laser beams have been smoothed with Kiniform Phase Plates in an attempt to remove deflection of the beams. The experiments have shown that this smoothing significantly improves the agreement with LASNEX calculations of implosion symmetry. The images of laser produced hot spots on the inside of the hohlraum case have been found to differ from LASNEX calculations, suggesting that some beam deflection or self-focusing may still be present or that emission from interpenetrating plasmas is an important component of the images. The measured neutron yields are in good agreement with simulations for vacuum hohlraums but are far different for gas-filled hohlraums. (c) 2000 American Institute of Physics

  15. Development of Laser-Induced Fluorescence Diagnostic for the Paul Trap Simulator Experiment

    CERN Document Server

    Chung, Moses; Efthimion, Philip; Gilson, Erik P; Majeski, Richard; Startsev, Edward

    2005-01-01

    The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. For the in-situ measurement of the transverse ion density profile in the PTSX device, which is essential for the study of beam mismatch and halo particle production, a laser-induced fluorescence diagnostic system is being developed. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. The installation of the barium ion source and the characterization of the tunable dye laser system are discussed. The design of the collection optics with an intensified CCD camera system is also discussed. Finally, initial test results using the laser-induced fluorescence diagnostic will be presented.

  16. Cannonball target experiment with the GEKKO laser system at ILE Osaka

    International Nuclear Information System (INIS)

    Yamanaka, C.; Azechi, H.; Fujiwara, E.

    1985-01-01

    The GEKKO series glass laser systems are now in operation for the Cannonball target experiments. GEKKO XII is a twelve-beam 30 kJ, 50 TW laser provided with two target chambers. Three types of GEKKO lasers cover the UV, blue, green and red frequency ranges. The Cannonball target displays an excellent performance in implosion. Two kinds of Cannonball target are proposed: the plasma Cannonball and the radiation Cannonball. The neutron yield is 4x10 10 , and the DT fuel density attains 10 g.cm -3 . Laser-to-X-ray conversion has been investigated. Cryogenic target implosion has been performed by using a tailored laser pulse to produce the flush at the core. Various kinds of new diagnostics are being developed. (author)

  17. Solenoid for Laser Induced Plasma Experiments at Janus

    Science.gov (United States)

    Klein, Sallee; Leferve, Heath; Kemp, Gregory; Mariscal, Derek; Rasmus, Alex; Williams, Jackson; Gillespie, Robb; Manuel, Mario; Kuranz, Carolyn; Keiter, Paul; Drake, R.

    2017-10-01

    Creating invariant magnetic fields for experiments involving laser induced plasmas is particularly challenging due to the high voltages at which the solenoid must be pulsed. Creating a solenoid resilient enough to survive through large numbers of voltage discharges, enabling it to endure a campaign lasting several weeks, is exceptionally difficult. Here we present a solenoid that is robust through 40 μs pulses at a 13 kV potential. This solenoid is a vast improvement over our previously fielded designs in peak magnetic field capabilities and robustness. Designed to be operated at small-scale laser facilities, the solenoid housing allows for versatility of experimental set-ups among diagnostic and target positions. Within the perpendicular field axis at the center there is 300 degrees of clearance which can be easily modified to meet the needs of a specific experiment, as well as an f/3 cone for transmitted or backscattered light. After initial design efforts, these solenoids are relatively inexpensive to manufacture.

  18. Advanced diagnostics for laser plasma interaction studies and some recent experiments

    International Nuclear Information System (INIS)

    Chaurasia, S.; Munda, D.S.; Dhareshwar, L.J.

    2008-10-01

    The complete characterization of Laser plasma interaction studies related to inertial confinement fusion laser and Equation of state (EOS) studies needs many diagnostics to explain the several physical phenomena occurring simultaneously in the laser produced plasma. This involves many on ion emission are important to understand physical phenomena which are responsible for generation of laser plasma as well as its interaction with an intense laser. In this report we describe the development of various x-ray diagnostics which are used in determining temporal, spatial and spectral properties of x-rays radiated from laser produced plasma. Diagnostics which have been used in experiments for investigation of laser-produced plasma as a source of ions are also described. Techniques using an optical streak camera and VISAR which are being used in the Equation of States (EOS) studies of various materials, which are important for material science, astrophysics as well as ICF is described in details. (author)

  19. High-intensity subpicosecond laser pulse propagation in a 1-cm capillary tube and fast ignitor experiments

    International Nuclear Information System (INIS)

    Malka, G.; Courtois, C.; Cros, B.; Matthieussent, G.; Borghesi, M.; Gaillard, R.; Mackinnon, A.J.; Willi, O.; Danson, C.; Neely, D.; Altenberd, D.; Feurer, T.; Forster, E.; Gibbon, P.; Sauerbray, R.; Teubner, U.; Theobald, W.; Uschmann, I.; Amiranoff, F.; Baton, S.; Gremillet, L.; Fuchs, J.; Marques, J.R.; Gallant, P.; Kieffer, J.C.; Pepin, H.; Adam, J.C.; Heron, A.; Laval, G.; Mora, P.

    2000-01-01

    We present an abstract of ultra short and intense laser plasma interaction experiments which were performed with the 100 TW P102 laser facility at CEA/Limeil-Valenton. Laser interaction at relativistic regime (I>10 18 W/cm 2 ) has been investigated with different 'targets': overdense plasma, underdense plasma, free electrons and capillary tube. These experiments are of great interests for the Fast Ignitor concept and the Laser Particle Accelerator. (authors)

  20. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

    2013-01-01

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  1. Design of indirectly driven, high-compression Inertial Confinement Fusion implosions with improved hydrodynamic stability using a 4-shock adiabat-shaped drive

    Energy Technology Data Exchange (ETDEWEB)

    Milovich, J. L., E-mail: milovich1@llnl.gov; Robey, H. F.; Clark, D. S.; Baker, K. L.; Casey, D. T.; Cerjan, C.; Field, J.; MacPhee, A. G.; Pak, A.; Patel, P. K.; Peterson, J. L.; Smalyuk, V. A.; Weber, C. R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-12-15

    Experimental results from indirectly driven ignition implosions during the National Ignition Campaign (NIC) [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] achieved a record compression of the central deuterium-tritium fuel layer with measured areal densities up to 1.2 g/cm{sup 2}, but with significantly lower total neutron yields (between 1.5 × 10{sup 14} and 5.5 × 10{sup 14}) than predicted, approximately 10% of the 2D simulated yield. An order of magnitude improvement in the neutron yield was subsequently obtained in the “high-foot” experiments [O. A. Hurricane et al., Nature 506, 343 (2014)]. However, this yield was obtained at the expense of fuel compression due to deliberately higher fuel adiabat. In this paper, the design of an adiabat-shaped implosion is presented, in which the laser pulse is tailored to achieve similar resistance to ablation-front instability growth, but with a low fuel adiabat to achieve high compression. Comparison with measured performance shows a factor of 3–10× improvement in the neutron yield (>40% of predicted simulated yield) over similar NIC implosions, while maintaining a reasonable fuel compression of >1 g/cm{sup 2}. Extension of these designs to higher laser power and energy is discussed to further explore the trade-off between increased implosion velocity and the deleterious effects of hydrodynamic instabilities.

  2. Jet laser ion source

    International Nuclear Information System (INIS)

    Dem'yanov, A.V.; Sidorov, S.V.

    1994-01-01

    External laser injector of multicharged ions (MCI) is developed in which wide-aperture aberration-free wire gauze spherical shape electrodes are applied for effective MCI extraction from laser plasma and beam focusing. Axial plasma compression by solenoid magnetic field is used to reduce ion losses due to transverse movement of the scattering laser plasma. Transverse magnetic field created by another solenoid facilitates the effective laser plasma braking and consequently, leads to the narrowing of energy spectrum of plasma ions and its shift towards lower energies. 2 refs.; 3 figs

  3. Design of an Experiment to Observe Laser-Plasma Interactions on NIKE

    Science.gov (United States)

    Phillips, L.; Weaver, J.; Manheimer, W.; Zalesak, S.; Schmitt, A.; Fyfe, D.; Afeyan, B.; Charbonneau-Lefort, M.

    2007-11-01

    Recent proposed designs (Obenschain et al., Phys. Plasmas 13 056320 (2006)) for direct-drive ICF targets for energy applications involve high implosion velocities combined with higher laser irradiances. The use of high irradiances increases the likelihood of deleterious laser plasma instabilities (LPI) that may lead, for example, to the generation of fast electrons. The proposed use of a 248 nm KrF laser to drive these targets is expected to minimize LPI; this is being studied by experiments at NRL's NIKE facility. We used a modification of the FAST code that models laser pulses with arbitrary spatial and temporal profiles to assist in designing these experiments. The goal is to design targets and pulseshapes to create plasma conditions that will produce sufficient growth of LPI to be observable on NIKE. Using, for example, a cryogenic DT target that is heated by a brief pulse and allowed to expand freely before interacting with a second, high-intensity pulse, allows the development of long scalelengths at low electron temperatures and leads to a predicted 20-efold growth in two-plasmon amplitude.

  4. Short wavelength laser-plasma interaction experiments in a spherical geometry

    International Nuclear Information System (INIS)

    Keck, R.L.

    1984-01-01

    Short wavelength (250 to 500 nm) lasers should provide reduced fast electron preheat and increased laser-pellet coupling efficiency when used as laser fusion drivers. As part of an ongoing effort to study short wavelength laser plasm interaction, six beams of the 24 beam OMEGA Nd-glass laser system have been converted to operation at the third harmonic. This system is capable of providing in excess of 250 Joules of 351 nm light on spherical targets at intensities up to 2 x 10/sup 15/ W/cm/sup 2/. To date, experiments have been performed to study the uniformity of irradiation, laser absorption, fast electron production and preheat, energy transport within the target and underdense plasma instabilities. Both x-ray continuum measurements and Kα line measurements indicate that the absorption is dominated by inverse bremsstrahlung. Electron energy transport has been studied using x-ray burn-through and charge collector measurements. The results show that with 351 nm irradiation ablation pressures of order 100 Mbars are generated at intensities of 10/sup 15/ W/cm/sup 2/

  5. Measurements of the toroidal plasma rotation velocity in TFTR major-radius compression experiments with auxiliary neutral beam heating

    International Nuclear Information System (INIS)

    Bitter, M.; Scott, S.; Wong, K.L.

    1986-07-01

    The time history of the central toroidal plasma rotation velocity in Tokamak Fusion Test Reactor (TFTR) experiments with auxiliary heating by neutral deuterium beam injection and major-radius compression has been measured from the Doppler shift of the emitted TiXXI-Kα line radiation. The experiments were conducted for neutral beam powers in the range from 2.1 to 3.8 MW and line-averaged densities in the range from 1.8 to 3.0 x 10 19 m -2 . The observed rotation velocity increase during compression is in agreement with results from modeling calculations which assume classical slowing-down of the injected fast deuterium ions and momentum damping at the rate established in the precompression plasma

  6. A control system for a free electron laser experiment

    International Nuclear Information System (INIS)

    Giove, D.

    1992-01-01

    The general layout of a control and data acquisition system for a Free Electron Laser experiment will be discussed. Some general considerations about the requirements and the architecture of the whole system will be developed. (author)

  7. Coherent structures in ablatively compressed ICF targets and Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Pant, H.C.; Desai, T.

    1996-01-01

    One of the major issues in laser induced inertial confinement fusion (ICF) is a stable ablative compression of spherical fusion pellets. The main impediment in achievement of this objective is Rayleigh-Taylor instability at the pellet's ablation front. Under sufficiently high acceleration this instability can grow out of noise. However, it can also arise either due to non-uniform laser intensity distribution over the pellet surface or due to pellet wall areal mass irregularity. Coherent structures in the dense target behind the ablation front can be effectively utilised for stabilisation of the Rayleigh-Taylor phenomenon. Such coherent structures in the form of a super lattice can be created by doping the pellet pusher with high atomic number (Z) micro particles. A compressed-cool pusher under laser irradiation behaves like a strongly correlated non ideal plasma when compressed to sufficiently high density such that the non ideality parameter exceeds unity. Moreover, the nonideality parameter for high Z microinclusions may exceed a critical value of 180 and as a consequence they remain in the form of intact clusters, maintaining the superlattice intact during ablative acceleration. Micro-hetrogeneity and its superlattice plays an important role in stabilization of Rayleigh-Taylor instability, through a variety of mechanisms. (orig.)

  8. Effect of low level laser therapy on chronic compression of the dorsal root ganglion.

    Directory of Open Access Journals (Sweden)

    Yi-Jen Chen

    Full Text Available Dorsal root ganglia (DRG are vulnerable to physical injury of the intervertebral foramen, and chronic compression of the DRG (CCD an result in nerve root damage with persistent morbidity. The purpose of this study was to evaluate the effects of low level laser therapy (LLLT on the DRG in a CCD model and to determine the mechanisms underlying these effects. CCD rats had L-shaped stainless-steel rods inserted into the fourth and fifth lumbar intervertebral foramen, and the rats were then subjected to 0 or 8 J/cm2 LLLT for 8 consecutive days following CCD surgery. Pain and heat stimuli were applied to test for hyperalgesia following CCD. The levels of TNF-α, IL-1β and growth-associated protein-43 (GAP-43 messenger RNA (mRNA expression were measured via real-time PCR, and protein expression levels were analyzed through immunohistochemical analyses. Our data indicate that LLLT significantly decreased the tolerable sensitivity to pain and heat stimuli in the CCD groups. The expression levels of the pro-inflammatory cytokines TNF-α and IL-1β were increased following CCD, and we found that these increases could be reduced by the application of LLLT. Furthermore, the expression of GAP-43 was enhanced by LLLT. In conclusion, LLLT was able to enhance neural regeneration in rats following CCD and improve rat ambulatory behavior. The therapeutic effects of LLLT on the DRG during CCD may be exerted through suppression of the inflammatory response and induction of neuronal repair genes. These results suggest potential clinical applications for LLLT in the treatment of compression-induced neuronal disorders.

  9. Proposed development of novel diagnostics for intense, ultrafast laser-plasma experiments at JAEA-KPSI

    International Nuclear Information System (INIS)

    Bolton, Paul R.; Tatchyn, Roman; Fukuda, Yuji; Kando, Masaki; Daito, Izuru; Ma, Jinglong; Chen, Liming; Pirozhkov, Alexander; Tajima, Toshiki

    2007-01-01

    Development of new diagnostics is critical for future laser-plasma accelerators, laser-driven light sources and for x-ray FELs. Recent laser wakefield electron acceleration developments and novel beam-based light source schemes (such as free electron lasers) obviate the need for next generation ultrafast diagnostics, capable of temporal resolution of a few femtoseconds (and in some cases attoseconds) for laser pulses (high order harmonics), x-ray pulses and electron bunches. Single shot detection capability in noninvasive and parasitic modes is also important. Alterations of laser pulse spectra and the associated dynamics can be informative diagnostics. The portion of a high intensity laser pulse that is transmitted through a self-induced underdense plasma (such as in laser wakefield acceleration LWFA schemes) carries the effects of plasma processes it has experienced. A distinction between the self-modulated laser wakefield (SMLWF) acceleration regime and the forced laser wakefield (FLWF) acceleration regime is in the spectral signature of the transmitted ir laser pulse. The former regime generates sidebands from stimulated Raman forward scattering (SRS-F) and the latter exhibits general spectral broadening that evidences ir laser pulse compression. Transmitted spectral effects can diagnose these acceleration regimes. Existing noninvasive electro-optic (EO) schemes for detection of ultrashort electron bunches are limited by material properties to temporal resolution at the 50-100 femtosecond level. While timing jitter at conventional accelerators is of this order (or greater), single bunch longitudinal profile measurements can require improvement of at least an order of magnitude. A new FO technique is described here which monitors enhancement and associated dynamics of spectral components in a probe pulse. Three correlation schemes for detecting ultrashort x-ray pulses are described. Two-photon absorption in tailored ion targets is proposed for scanning auto

  10. High-intensity subpicosecond laser pulse propagation in a 1-cm capillary tube and fast ignitor experiments

    Energy Technology Data Exchange (ETDEWEB)

    Malka, G.; Courtois, C.; Cros, B.; Matthieussent, G. [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique des Gaz et des Plasmas; Blanchot, N.; Bonnaud, G.; Busquet, M.; Canaud, B.; Desenne, D.; Diskier, L.; Garconnet, J.P.; Louis-Jacquet, M.; Lefebvre, E.; Lours, L.; Mens, A.; Miquel, J.L.; Peyrusse, O.; Rousseaux, C. [CEA/Limeil Valenton, 94 - Villeneuve Saint Georges (France); Borghesi, M.; Gaillard, R.; Mackinnon, A.J.; Willi, O. [Imperial Coll., Plasma Physics Groups, London (United Kingdom); Danson, C.; Neely, D. [Rutherford Appleton Lab., Chilton (United Kingdom); Altenberd, D.; Feurer, T.; Forster, E.; Gibbon, P.; Sauerbray, R.; Teubner, U.; Theobald, W.; Uschmann, I. [Institut fur Optik und Quantenelektronik, Jena (Germany); Amiranoff, F.; Baton, S.; Gremillet, L.; Fuchs, J.; Marques, J.R. [Ecole Polytechnique, Lab. d' Utilisation de Lasers Intenses, CNRS-CEA, 91 - Palaiseau (France); Gallant, P.; Kieffer, J.C.; Pepin, H. [INRS Energie et Materiaux, Quebec (Canada); Adam, J.C.; Heron, A.; Laval, G.; Mora, P. [Ecole Polytechnique, 91 - Palaiseau (France). Centre de Physique Theorique

    2000-07-01

    We present an abstract of ultra short and intense laser plasma interaction experiments which were performed with the 100 TW P102 laser facility at CEA/Limeil-Valenton. Laser interaction at relativistic regime (I>10{sup 18} W/cm{sup 2}) has been investigated with different 'targets': overdense plasma, underdense plasma, free electrons and capillary tube. These experiments are of great interests for the Fast Ignitor concept and the Laser Particle Accelerator. (authors)

  11. New methods of generation of ultrashort laser pulses for ranging

    Science.gov (United States)

    Jelinkova, Helena; Hamal, Karel; Kubecek, V.; Prochazka, Ivan

    1993-01-01

    To reach the millimeter satellite laser ranging accuracy, the goal for nineties, new laser ranging techniques have to be applied. To increase the laser ranging precision, the application of the ultrashort laser pulses in connection with the new signal detection and processing techniques, is inevitable. The two wavelength laser ranging is one of the ways to measure the atmospheric dispersion to improve the existing atmospheric correction models and hence, to increase the overall system ranging accuracy to the desired value. We are presenting a review of several nonstandard techniques of ultrashort laser pulses generation, which may be utilized for laser ranging: compression of the nanosecond pulses using stimulated Brillouin and Raman backscattering; compression of the mode-locked pulses using Raman backscattering; passive mode-locking technique with nonlinear mirror; and passive mode-locking technique with the negative feedback.

  12. Laser-Induced Fluorescence diagnostic of barium ion plasmas in the Paul Trap Simulator Experiment

    International Nuclear Information System (INIS)

    Chung, Moses; Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.

    2005-01-01

    The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. To investigate the ion plasma microstate in PTSX, including the ion density profile and the ion velocity distribution function, a laser-induced fluorescence diagnostic system is being developed as a nondestructive diagnostic. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. A feasibility study of the laser-induced fluorescence diagnostic using barium ions is presented with the characterization of a tunable dye laser. The installation of the barium ion source and the development of the laser-induced fluorescence diagnostic system are also discussed

  13. Direct Observation of Strong Ion Coupling in Laser-Driven Shock-Compressed Targets

    International Nuclear Information System (INIS)

    Ravasio, A.; Benuzzi-Mounaix, A.; Loupias, B.; Ozaki, N.; Rabec le Gloahec, M.; Koenig, M.; Gregori, G.; Daligault, J.; Delserieys, A.; Riley, D.; Faenov, A. Ya.; Pikuz, T. A.

    2007-01-01

    In this Letter we report on a near collective x-ray scattering experiment on shock-compressed targets. A highly coupled Al plasma was generated and probed by spectrally resolving an x-ray source forward scattered by the sample. A significant reduction in the intensity of the elastic scatter was observed, which we attribute to the formation of an incipient long-range order. This speculation is confirmed by x-ray scattering calculations accounting for both electron degeneracy and strong coupling effects. Measurements from rear side visible diagnostics are consistent with the plasma parameters inferred from x-ray scattering data. These results give the experimental evidence of the strongly coupled ionic dynamics in dense plasmas

  14. Dynamic Response and Failure Mechanism of Brittle Rocks Under Combined Compression-Shear Loading Experiments

    Science.gov (United States)

    Xu, Yuan; Dai, Feng

    2018-03-01

    A novel method is developed for characterizing the mechanical response and failure mechanism of brittle rocks under dynamic compression-shear loading: an inclined cylinder specimen using a modified split Hopkinson pressure bar (SHPB) system. With the specimen axis inclining to the loading direction of SHPB, a shear component can be introduced into the specimen. Both static and dynamic experiments are conducted on sandstone specimens. Given carefully pulse shaping, the dynamic equilibrium of the inclined specimens can be satisfied, and thus the quasi-static data reduction is employed. The normal and shear stress-strain relationships of specimens are subsequently established. The progressive failure process of the specimen illustrated via high-speed photographs manifests a mixed failure mode accommodating both the shear-dominated failure and the localized tensile damage. The elastic and shear moduli exhibit certain loading-path dependence under quasi-static loading but loading-path insensitivity under high loading rates. Loading rate dependence is evidently demonstrated through the failure characteristics involving fragmentation, compression and shear strength and failure surfaces based on Drucker-Prager criterion. Our proposed method is convenient and reliable to study the dynamic response and failure mechanism of rocks under combined compression-shear loading.

  15. Understanding compressive deformation behavior of porous Ti using finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Sandipan; Khutia, Niloy [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur (India); Das, Debdulal [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur (India); Das, Mitun, E-mail: mitun@cgcri.res.in [Bioceramics and Coating Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India); Balla, Vamsi Krishna [Bioceramics and Coating Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India); Bandyopadhyay, Amit [W. M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Chowdhury, Amit Roy, E-mail: arcbesu@gmail.com [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur (India)

    2016-07-01

    In the present study, porous commercially pure (CP) Ti samples with different volume fraction of porosities were fabricated using a commercial additive manufacturing technique namely laser engineered net shaping (LENS™). Mechanical behavior of solid and porous samples was evaluated at room temperature under quasi-static compressive loading. Fracture surfaces of the failed samples were analyzed to determine the failure modes. Finite Element (FE) analysis using representative volume element (RVE) model and micro-computed tomography (CT) based model have been performed to understand the deformation behavior of laser deposited solid and porous CP-Ti samples. In vitro cell culture on laser processed porous CP-Ti surfaces showed normal cell proliferation with time, and confirmed non-toxic nature of these samples. - Highlights: • Porous CP-Ti samples fabricated using additive manufacturing technique • Compressive deformation behavior of porous samples closely matches with micro-CT and RVE based analysis • In vitro studies showed better cell proliferation with time on porous CP-Ti surfaces.

  16. Understanding compressive deformation behavior of porous Ti using finite element analysis

    International Nuclear Information System (INIS)

    Roy, Sandipan; Khutia, Niloy; Das, Debdulal; Das, Mitun; Balla, Vamsi Krishna; Bandyopadhyay, Amit; Chowdhury, Amit Roy

    2016-01-01

    In the present study, porous commercially pure (CP) Ti samples with different volume fraction of porosities were fabricated using a commercial additive manufacturing technique namely laser engineered net shaping (LENS™). Mechanical behavior of solid and porous samples was evaluated at room temperature under quasi-static compressive loading. Fracture surfaces of the failed samples were analyzed to determine the failure modes. Finite Element (FE) analysis using representative volume element (RVE) model and micro-computed tomography (CT) based model have been performed to understand the deformation behavior of laser deposited solid and porous CP-Ti samples. In vitro cell culture on laser processed porous CP-Ti surfaces showed normal cell proliferation with time, and confirmed non-toxic nature of these samples. - Highlights: • Porous CP-Ti samples fabricated using additive manufacturing technique • Compressive deformation behavior of porous samples closely matches with micro-CT and RVE based analysis • In vitro studies showed better cell proliferation with time on porous CP-Ti surfaces

  17. Beam wandering of femtosecond laser filament in air.

    Science.gov (United States)

    Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

    2015-10-05

    The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.

  18. Quasi-isentropic compression using compressed water flow generated by underwater electrical explosion of a wire array

    Science.gov (United States)

    Gurovich, V.; Virozub, A.; Rososhek, A.; Bland, S.; Spielman, R. B.; Krasik, Ya. E.

    2018-05-01

    A major experimental research area in material equation-of-state today involves the use of off-Hugoniot measurements rather than shock experiments that give only Hugoniot data. There is a wide range of applications using quasi-isentropic compression of matter including the direct measurement of the complete isentrope of materials in a single experiment and minimizing the heating of flyer plates for high-velocity shock measurements. We propose a novel approach to generating quasi-isentropic compression of matter. Using analytical modeling and hydrodynamic simulations, we show that a working fluid composed of compressed water, generated by an underwater electrical explosion of a planar wire array, might be used to efficiently drive the quasi-isentropic compression of a copper target to pressures ˜2 × 1011 Pa without any complex target designs.

  19. Experiments of Laser Pointing Stability in Air and in Vacuum to Validate Micrometric Positioning Sensor

    CERN Document Server

    Stern, G; Piedigrossi, D; Sandomierski, J; Sosin, M; Geiger, A; Guillaume, S

    2014-01-01

    Aligning accelerator components over 200m with 10 μm accuracy is a challenging task within the Compact Linear Collider (CLIC) study. A solution based on laser beam in vacuum as straight line reference is proposed. The positions of the accelerator’s components are measured with respect to the laser beam by sensors made of camera/shutter assemblies. To validate these sensors, laser pointing stability has to be studied over 200m. We perform experiments in air and in vacuum in order to know how laser pointing stability varies with the distance of propagation and with the environment. The experiments show that the standard deviations of the laser spot coordinates increase with the distance of propagation. They also show that the standard deviations are much smaller in vacuum (8 μm at 35m) than in air (2000 μm at 200m). Our experiment validates the concept of laser beam in vacuum with camera/shutter assembly for micrometric positioning over 35m. It also gives an estimation of the achievable precision.

  20. PHELIX: A petawatt-class laser recently commissioned for experiments in plasma and atomic physics

    International Nuclear Information System (INIS)

    Bagnoud, V; Blazevic, A; Borneis, S; Eisenbarth, U; Fils, J; Goette, S; Kuehl, Th; Onkels, E; Stoehlker, T; Tauschwitz, A; Zimmer, D; Witte, K

    2009-01-01

    The PHELIX facility is available to users since 2008. Nanosecond pulses up to 500 J are utilized at present for experiments combining the heavy ions accelerated at the GSI LINAC facility, while sub-picosecond 200-TW pulses are used in laser stand-alone experiments. A review of the laser performance and future developments is shown.

  1. PHELIX: A petawatt-class laser recently commissioned for experiments in plasma and atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Bagnoud, V; Blazevic, A; Borneis, S; Eisenbarth, U; Fils, J; Goette, S; Kuehl, Th; Onkels, E; Stoehlker, T; Tauschwitz, A; Zimmer, D; Witte, K, E-mail: v.bagnoud@gsi.d [GSI, Helmholtzzentrum fuer Schwerionenforschung mbH, Planckstr. 1, D-64291Darmstadt (Germany)

    2009-11-01

    The PHELIX facility is available to users since 2008. Nanosecond pulses up to 500 J are utilized at present for experiments combining the heavy ions accelerated at the GSI LINAC facility, while sub-picosecond 200-TW pulses are used in laser stand-alone experiments. A review of the laser performance and future developments is shown.

  2. Fast ignition experimental and theoretical researches toward Fast Ignition Realization Experiment (FIREX)

    International Nuclear Information System (INIS)

    Mima, K.

    2002-01-01

    In 2000, the output energy of the peta watt module added to Gekko XII reached a level of 100 J in one pico-second. CD plastic shell pellets with or without cone guide are imploded by a few kJ/1 ns green beams of the Gekko XII laser, which are heated by the PWM laser. By the experiments, we found that D-D neutron yields are enhanced by one order of magnitude for both spherical implosion and cone guide implosion. In those experiments, it is found that the heating laser energy was not transferred into the core plasmas effectively in the case of without cone because of strong dumping of the intense laser pulse in coronal plasmas. Therefore, we concluded that the more efficient core heating occurs in the cone guide target and it will be better as an ignition target. In the peta watto laser experiments which is going in this Aprile, we will inject 500 J/1 ps pulse into cone targets to heat compressed CD plasmas with a density of 50-100 g/cc. In this experiment, it is expected that the plasma is heated to higher than 1 keV. The detail of the experiment will be reported in the conference. (author)

  3. OMEGA ICF experiments and preparations for direct drive on NIF

    International Nuclear Information System (INIS)

    McCrory, R.L.; Bahr, R.E.; Betti, R.

    2001-01-01

    Direct-drive laser-fusion ignition experiments rely on detailed understanding and control of irradiation uniformity, the Rayleigh-Taylor instability, and target fabrication. LLE is investigating various theoretical aspects of a direct-drive NIF ignition target based on an 'all-DT' design: a spherical target of ∼3.4-mm diameter, 1 to 2 μm of CH wall thickness, and an ∼340-μm DT-ice layer near the triple point of DT (∼19 K). OMEGA experiments are designed to address the critical issues related to direct-drive laser fusion and to provide the necessary data to validate the predictive capability of LLE computer codes. The cryogenic targets to be used on OMEGA are hydrodynamically equivalent to those planned for the NIF. The current experimental studies on OMEGA address the essential components of direct-drive laser fusion: irradiation uniformity and laser imprinting, Rayleigh-Taylor growth and saturation, compressed core performance and shell fuel mixing, laser plasma interactions and their effect on target performance, and cryogenic target fabrication and handling. (author)

  4. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Lowell [Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Earth Sciences, Montana State University, Bozeman, Montana 59717 (United States); Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Wenk, Hans-Rudolf; Alarcon, Eloisa Zepeda [Department of Earth and Planetary Science, University of California, Berkeley, California 94720 (United States); Raju, Selva Vennila [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); HiPSEC, Department of Physics, University of Nevada, Las Vegas, Nevada 89154 (United States); Knight, Jason; MacDowell, Alastair [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); Williams, Quentin [Department of Earth and Planetary Science, University of California, Santa Cruz, California 95064 (United States)

    2013-02-15

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg{sub 0.9}Fe{sub 0.1})O in Run3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  5. Molecular dynamics stimulations to study laser dye aggregation in water (comparison with experiments)

    International Nuclear Information System (INIS)

    Dare-Doyen, St.; Doizi, D.

    2000-01-01

    A laser facility consists of dye laser chains where the active medium is composed of fluorescent dyes dissolved in ethanol. The use of water as a solvent would offer two major advantages: greater safety of the laser facility by drastically reducing fire risks, easier design of the laser beam correcting devices required at the end of the dye laser chains, thanks to the properties of water. Unfortunately, laser dyes exhibit poor optical properties in water, due to the formation of dye aggregates. Molecular dynamics simulations were used to study and develop means to prevent this behavior between two charged species. The results were compared with NMR (Nuclear Magnetic Resonance) experiments

  6. Laser driven shock wave experiments for equation of state studies at megabar pressures

    CERN Document Server

    Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.

  7. Laser driven shock wave experiments for equation of state studies at megabar pressures

    International Nuclear Information System (INIS)

    Pant, H C; Shukla, M; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 μm wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments

  8. An Approach Toward Synthesis of Bridgmanite in Dynamic Compression Experiments

    Science.gov (United States)

    Reppart, J. J.

    2015-12-01

    Bridgmanite occurs in heavily shocked meteorites and provides a useful constraint on pressure-temperature conditions during shock-metamorphism. Its occurrence also provides constraints on the shock release path. Shock-release and shock duration are important parameters in estimating the size of impactors that generate the observed shock metamorphic record. Thus, it is timely to examine if bridgmanite can be synthesized in dynamic compression experiments with the goal of establishing a correlation between shock duration and grainsize. Up to now only one high pressure polymorph of an Mg-silicate has been synthesized AND recovered in a shock experiment (wadsleyite). Therefore, it is not given that shock synthesis of bridgmanite is possible. This project started recently, so we present an outline of shock experiment designs and potentially results from the first experiments. FUNDING ACKNOWLEDGMENT UNLV HiPSEC: This research was sponsored (or sponsored in part) by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement #DE-NA0001982. HPCAT: "[Portions of this work were]/[This work was] performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357."

  9. Investigation Into the Utilization of 3D Printing in Laser Cooling Experiments

    Science.gov (United States)

    Hazlett, Eric; Nelson, Brandon; de Leon, Sam Diaz; Shaw, Jonah

    2016-05-01

    With the advancement of 3D printing new opportunities are abound in many different fields, but with the balance between the precisions of atomic physics experiments and the material properties of current 3D printers the benefit of 3D printing technology needs to be investigated. We report on the progress of two investigations of 3D printing of benefit to atomic physics experiments: laser feedback module and the other being an optical chopper. The first investigation looks into creation of a 3D printed laser diode feedback module. This 3D printed module would allow for the quick realization of an external cavity diode laser that would have an adjustable cavity distance. We will report on the first tests of this system, by looking at Rb spectroscopy and mode-hop free tuning range as well as possibilities of using these lasers for MOT generation. We will also discuss our investigation into a 3D-printed optical chopper that utilizes an Arduino and a computer hard drive motor. By implementing an additional Arduino we create a low cost way to quickly measure laser beam waists.

  10. Measurements of three dimensional residual stress distribution on laser irradiated spot

    International Nuclear Information System (INIS)

    Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

    2004-01-01

    Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

  11. Evaluation of a wavelet-based compression algorithm applied to the silicon drift detectors data of the ALICE experiment at CERN

    International Nuclear Information System (INIS)

    Falchieri, Davide; Gandolfi, Enzo; Masotti, Matteo

    2004-01-01

    This paper evaluates the performances of a wavelet-based compression algorithm applied to the data produced by the silicon drift detectors of the ALICE experiment at CERN. This compression algorithm is a general purpose lossy technique, in other words, its application could prove useful even on a wide range of other data reduction's problems. In particular the design targets relevant for our wavelet-based compression algorithm are the following ones: a high-compression coefficient, a reconstruction error as small as possible and a very limited execution time. Interestingly, the results obtained are quite close to the ones achieved by the algorithm implemented in the first prototype of the chip CARLOS, the chip that will be used in the silicon drift detectors readout chain

  12. Laser fusion experiments at 2 TW. [Argus system; implosion of D-T filled glass microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Storm, E.K.; Ahlstrom, H.G.; Boyle, M.J.

    1976-10-01

    The Lawrence Livermore Laboratory Solid State Laser System, Arqus, has successfully performed laser implosion experiments at power levels exceeding 2 TW. D-T filled glass microspheres have been imploded to yield thermonuclear reaction products in excess of 5 x 10/sup 8/ per event. Neutron and ..cap alpha.. time-of-flight measurements indicate that D-T ion temperatures of approximately 5-6 keV and a density confinement time product (n tau) of approximately 1 x 10/sup 12/ were obtained in these experiments. Typically two 40J, 40 psec pulses of 1.06 ..mu..m light were focused on targets using 20 cm aperture f/1 lenses, producing intensities at the target in excess of 10/sup 16/ W/cm/sup 2/. An extensive array of diagnostics routinely monitored the laser performance and the laser target interaction process. Measurements of absorption and asymmetry in both the scattered light distribution and the ion blow off is evidence for non-classical absorption mechanisms and density scale heights of the order of 2 ..mu..m or less. The symmetry of the thermonuclear burn region is investigated by monitoring the ..cap alpha..-particle flux in several directions, and an experiment to image the thermonuclear burn region is in process. These experiments significantly extend our data base and our understanding of laser induced thermonuclear implosions and the basic laser plasma interaction physics from the 0.4 to 0.7 TW level of previous experiments.

  13. Compressed Natural Gas (CNG) Transit Bus Experience Survey: April 2009--April 2010

    Energy Technology Data Exchange (ETDEWEB)

    Adams, R.; Horne, D. B.

    2010-09-01

    This survey was commissioned by the U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) to collect and analyze experiential data and information from a cross-section of U.S. transit agencies with varying degrees of compressed natural gas (CNG) bus and station experience. This information will be used to assist DOE and NREL in determining areas of success and areas where further technical or other assistance might be required, and to assist them in focusing on areas judged by the CNG transit community as priority items.

  14. Experiment of Laser Pointing Stability on Different Surfaces to validate Micrometric Positioning Sensor

    CERN Document Server

    AUTHOR|(SzGeCERN)721924; Mainaud Durand, Helene; Piedigrossi, Didier; Sandomierski, Jacek; Sosin, Mateusz; Geiger, Alain; Guillaume, Sebastien

    2014-01-01

    CLIC requires 10 μm precision and accuracy over 200m for the pre-alignment of beam related components. A solution based on laser beam as straight line reference is being studied at CERN. It involves camera/shutter assemblies as micrometric positioning sensors. To validate the sensors, it is necessary to determine an appropriate material for the shutter in terms of laser pointing stability. Experiments are carried out with paper, metal and ceramic surfaces. This paper presents the standard deviations of the laser spot coordinates obtained on the different surfaces, as well as the measurement error. Our experiments validate the choice of paper and ceramic for the shutter of the micrometric positioning sensor. It also provides an estimate of the achievable precision and accuracy of the determination of the laser spot centre with respect to the shutter coordinate system defined by reference targets.

  15. Effects of thermal conduction and compressibility on Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Takabe, Hideaki; Mima, Kunioki.

    1980-01-01

    In order to study the stability of the ablation front in laser driven implosion, the thermal conduction and compressibility effects on the Rayleigh-Taylor instability are considered. It is found that the thermal conduction effect cannot stabilize the Rayleigh-Taylor mode, but reduce the growth rate in the short wavelength case. But, the growth rate is found not to differ from the classical value √gk in the long wavelength limit, where the compressibility is essential. (author)

  16. Monolithic Yb-fiber femtosecond laser using photonic crystal fiber

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2008-01-01

    We demonstrate, both experimentally and theoretically, an environmentally stable monolithic all-PM modelocked femtosecond Yb-fiber laser, with laser output pulse compressed in a spliced-on low-loss hollow-core photonic crystal fiber. Our laser provides direct fiber-end delivery of 4 nJ pulses...

  17. Experiment and simulation study of laser dicing silicon with water-jet

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Jiading; Long, Yuhong, E-mail: longyuhong@guet.edu.cn; Tong, Youqun; Yang, Xiaoqing; Zhang, Bin; Zhou, Zupeng

    2016-11-30

    Highlights: • The explosive melt expulsion could be a dominant process for the laser ablating silicon in liquids with ns-pulsed laser of 1064 nm irradiating. • Self-focusing phenomenon was found and its causes are analyzed. • SPH modeling technique was employed to understand the effect of water and water-jet on debris removal during water-jet laser machining. - Abstract: Water-jet laser processing is an internationally advanced technique, which combines the advantages of laser processing with water jet cutting. In the study, the experiment of water-jet laser dicing are conducted with ns pulsed laser of 1064 nm irradiating, and Smooth Particle Hydrodynamic (SPH) technique by AUTODYN software was modeled to research the fluid dynamics of water and melt when water jet impacting molten material. The silicon surface morphology of the irradiated spots has an appearance as one can see in porous formation. The surface morphology exhibits a large number of cavities which indicates as bubble nucleation sites. The observed surface morphology shows that the explosive melt expulsion could be a dominant process for the laser ablating silicon in liquids with nanosecond pulse laser of 1064 nm irradiating. Self-focusing phenomenon was found and its causes are analyzed. Smooth Particle Hydrodynamic (SPH) modeling technique was employed to understand the effect of water and water-jet on debris removal during water-jet laser machining.

  18. Method for mounting laser fusion targets for irradiation

    Science.gov (United States)

    Fries, R. Jay; Farnum, Eugene H.; McCall, Gene H.

    1977-07-26

    Methods for preparing laser fusion targets of the ball-and-disk type are disclosed. Such targets are suitable for irradiation with one or two laser beams to produce the requisite uniform compression of the fuel material.

  19. Role of laser myringotomy in a pediatric otolaryngology practice: initial experience

    Science.gov (United States)

    Shah, Udayan K.

    2001-05-01

    A new technology (OtoLAM) to fenestrate the tympanic membrane with the carbon dioxide laser (CO2), in the office or the operating room, has been introduced over the last three years. While not new conceptually, this product offers the ability to easily create a precise window into the middle ear using a portable system. Controversy regarding the indications and benefits of this technique, amplified by the costs of the system and the marketing of the technology prior to extensive clinical testing, has plagued the clinical application of this technology. We report our experience over the past year with this system in a busy pediatric otolaryngology practice. Laser fenestration of the tympanic membrane has been useful for the insertion of tympanostomy tubes, and for the minimally invasive evaluation of the middle ear. Our small experience to date reveals that there is a limited role for laser tympanic membrane fenestration in a busy pediatric otolaryngology practice.

  20. Emittance control and RF bunch compression in the NSRRC photoinjector

    International Nuclear Information System (INIS)

    Lau, W.K.; Hung, S.B.; Lee, A.P.; Chou, C.S.; Huang, N.Y.

    2011-01-01

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  1. Compression of realistic laser pulses in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, John

    2009-01-01

    Dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap fiber is studied numerically. The performance of ideal parabolic input pulses is compared to pulses from a narrowband picosecond oscillator broadened by self-phase modulation during...... amplification. It is shown that the parabolic pulses are superior for compression of high-quality femtosecond pulses up to the few-megawatts level. With peak powers of 5-10 MW or higher, there is no significant difference in power scaling and pulse quality between the two pulse types for comparable values...... of power, duration, and bandwidth. The same conclusion is found for the peak power and energy of solitons formed beyond the point of maximal compression. Long-pass filtering of these solitons is shown to be a promising route to clean solitonlike output pulses with peak powers of several MW....

  2. Simple collision operators for direct Vlasov simulations of laser plasma interaction and transport

    International Nuclear Information System (INIS)

    Arber, T D; Sircombe, N J

    2010-01-01

    Non-local electron transport effects have a direct influence on the compression of cryogenic targets in laser driven ICF and target heating in high energy density experiments. There is a growing need for self-consistent models of laser plasma interactions coupled to nonlocal transport. We present a direct Vlasov solver that includes multiple species and a simple collision operator. This BGK model operator - which conserves particle density, energy and momentum - is fully implicit. For collisionless plasmas it has been shown that a double layer may be formed in which an accelerated, kinetic ion population satisfies the zero current condition. Here we extend this result to collisionalities of interest to laser driven ignition to assess the validity of nonlocal electron transport models based on fluid ions.

  3. DNABIT Compress - Genome compression algorithm.

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-22

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, "DNABIT Compress" for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that "DNABIT Compress" algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases.

  4. Physics of laser fusion. Volume III. High-power pulsed lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Eimerl, D.; George, E.V.; Trenholme, J.B.; Simmons, W.W.; Hunt, J.T.

    1982-09-01

    High-power pulsed lasers can deliver sufficient energy on inertial-confinement fusion (ICF) time scales (0.1 to 10 ns) to heat and compress deuterium-tritium fuel to fusion-reaction conditions. Several laser systems have been examined, including Nd:glass, CO 2 , KrF, and I 2 , for their ICF applicability. A great deal of developmental effort has been applied to the Nd:glass laser and the CO 2 gas laser systems; these systems now deliver > 10 4 J and 20 x 10 12 W to ICF targets. We are constructing the Nova Nd:glass laser at LLNL to provide > 100 kJ and > 100 x 10 12 W of 1-μm radiation for fusion experimentation in the mid-1980s. For ICF target gain > 100 times the laser input, we expect that the laser driver must deliver approx. 3 to 5 MJ of energy on a time scale of 10 to 20 ns. In this paper we review the technological status of fusion-laser systems and outline approaches to constructing high-power pulsed laser drivers

  5. Laser driven particle acceleration

    International Nuclear Information System (INIS)

    Faure, J.

    2009-06-01

    This dissertation summarizes the last ten years of research at the Laboratory of Applied Optics on laser-plasma based electron acceleration. The main result consists of the development and study of a relativistic electron source with unique properties: high energy (100-300 MeV) in short distances (few millimeters), mono-energetic, ultra-short (few fs), stable and tunable. The manuscript describes the steps that led to understanding the physics, and then mastering it in order to produce this new electron source. Non linear propagation of the laser pulse in the plasma is first presented, with phenomena such as non linear wakefield excitation, relativistic and ponderomotive self-focusing in the short pulse regime, self-compression. Acceleration and injection of electrons are then reviewed from a theoretical perspective. Experimental demonstrations of self-injection in the bubble regime and then colliding pulse injection are then presented. These experiments were among the first to produce monoenergetic, high quality, stable and tunable electron beams from a laser-plasma accelerator. The last two chapters are dedicated to the characterization of the electron beam using transition radiation and to its applications to gamma radiography and radiotherapy. Finally, the perspectives of this research are presented in the conclusion. Scaling laws are used to determine the parameters that the electron beams will reach using peta-watt laser systems currently under construction. (author)

  6. Effects of Different Compression Techniques on Diagnostic Accuracies of Breast Masses on Digitized Mammograms

    International Nuclear Information System (INIS)

    Zhigang Liang; Xiangying Du; Jiabin Liu; Yanhui Yang; Dongdong Rong; Xinyu Y ao; Kuncheng Li

    2008-01-01

    Background: The JPEG 2000 compression technique has recently been introduced into the medical imaging field. It is critical to understand the effects of this technique on the detection of breast masses on digitized images by human observers. Purpose: To evaluate whether lossless and lossy techniques affect the diagnostic results of malignant and benign breast masses on digitized mammograms. Material and Methods: A total of 90 screen-film mammograms including craniocaudal and lateral views obtained from 45 patients were selected by two non-observing radiologists. Of these, 22 cases were benign lesions and 23 cases were malignant. The mammographic films were digitized by a laser film digitizer, and compressed to three levels (lossless and lossy 20:1 and 40:1) using the JPEG 2000 wavelet-based image compression algorithm. Four radiologists with 10-12 years' experience in mammography interpreted the original and compressed images. The time interval was 3 weeks for each reading session. A five-point malignancy scale was used, with a score of 1 corresponding to definitely not a malignant mass, a score of 2 referring to not a malignant mass, a score of 3 meaning possibly a malignant mass, a score of 4 being probably a malignant mass, and a score of 5 interpreted as definitely a malignant mass. The radiologists' performance was evaluated using receiver operating characteristic analysis. Results: The average Az values for all radiologists decreased from 0.8933 for the original uncompressed images to 0.8299 for the images compressed at 40:1. This difference was not statistically significant. The detection accuracy of the original images was better than that of the compressed images, and the Az values decreased with increasing compression ratio. Conclusion: Digitized mammograms compressed at 40:1 could be used to substitute original images in the diagnosis of breast cancer

  7. Combinatorial experiment in Ni-Ti thin films by laser interference structuring

    International Nuclear Information System (INIS)

    Liu, K.W.; Gachot, C.; Leibenguth, P.; Muecklich, F.

    2005-01-01

    Combinatorial experiments are achieved on periodically structured Ni-Ti thin film composition spreads by laser interference irradiation using a Nd:YAG laser. Continuous Ni-Ti compositional spreads covering almost the whole binary system are prepared by combining sputter mask, shutter and movement of substrate. The continuous compositional spread is subsequently micro-structured into a sample library consisting of well-defined lines of individual samples by laser interference irradiation. The composition and microstructure effects in continuous spread and sample libraries after laser structuring are explored by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and white light interferometry (WLI) microscopy. The sample library consists of individual samples with a distance of about 5 μm and a composition resolution as high as 0.1 at.% in between. Although, there are certain difficulties so far in obtaining the optimized laser fluence for the spread, the laser interference irradiation provides an effective way to prepare thin film libraries with around 200 sample lines within 1 mm

  8. Laser-synchrotron hybrid experiments. A photon to tickle - a photon to poke

    Energy Technology Data Exchange (ETDEWEB)

    Ederer, D.L.; Rubensson, J.E.; Mueller, D.R. (National Inst. of Standards and Technology, Gaithersburg, MD (United States)); Shuker, R. (Ben Gurion Univ., Beer Shiva (Israel)); O' Brien, W.L.; Jai, J.; Dong, Q.Y.; Callcott, T.A. (Tennessee Univ., Knoxville, TN (United States)); Carr, G.L. (Grumman Corporation Research Center, Bethpage, NY (United States)); Williams, G.P.; Hirschmugl, C.J. (National Synchrotron Light Source, Upton, NY (United States)); Etemad, S.; Inam, A. (Belcore, Redbank, NJ (United States)); Tanner, D.B. (Florida Univ., Gainesville, FL (United States))

    1992-08-01

    In this paper we present the preliminary results from a new experimental technique to synchronize the pulses from a mode-locked Nd-YAG laser to the light pulses in the VUV storage ring at the National Synchrotron Light Source (NSLS). We describe a method to electronically change the delay time between the laser pulses and the synchrotron pulses. We also illustrate a method to overlap the synchrotron pulses with the laser pulses in space and time. Preliminary results will be presented for two experiments. (orig.).

  9. Laser-driven shock-wave propagation in pure and layered targets

    International Nuclear Information System (INIS)

    Salzmann, D.; Eliezer, S.; Krumbein, A.D.; Gitter, L.

    1983-01-01

    The propagation properties of laser-driven shock waves in pure and layered polyethylene and aluminum slab targets are studied for a set of laser intensities and pulse widths. The laser-plasma simulations were carried out by means of our one-dimensional Lagrangian hydrodynamic code. It is shown that the various parts of a laser-driven compression wave undergo different thermodynamic trajectories: The shock front portion is on the Hugoniot curve whereas the rear part is closer to an adiabat. It is found that the shock front is accelerated into the cold material till troughly-equal0.8tau (where tau is the laser pulse width) and only later is a constant velocity propagation attained. The scaling laws obtained for the pressure and temperature of the compression wave in pure targets are in good agreement with those published in other works. In layered targets, high compression and pressure were found to occur at the interface of CH 2 on Al targets due to impedance mismatch but were not found when the layers were reversed. The persistence time of the high pressure on the interface in the CH 2 on Al case is long enough relative to the characteristic times of the plasma to have an appreciable influence on the shock-wave propagation into the aluminum layer. This high pressure and compression on the interface can be optimized by adjusting the CH 2 layer thickness

  10. Assessing the Effects of Data Compression in Simulations Using Physically Motivated Metrics

    Directory of Open Access Journals (Sweden)

    Daniel Laney

    2014-01-01

    Full Text Available This paper examines whether lossy compression can be used effectively in physics simulations as a possible strategy to combat the expected data-movement bottleneck in future high performance computing architectures. We show that, for the codes and simulations we tested, compression levels of 3–5X can be applied without causing significant changes to important physical quantities. Rather than applying signal processing error metrics, we utilize physics-based metrics appropriate for each code to assess the impact of compression. We evaluate three different simulation codes: a Lagrangian shock-hydrodynamics code, an Eulerian higher-order hydrodynamics turbulence modeling code, and an Eulerian coupled laser-plasma interaction code. We compress relevant quantities after each time-step to approximate the effects of tightly coupled compression and study the compression rates to estimate memory and disk-bandwidth reduction. We find that the error characteristics of compression algorithms must be carefully considered in the context of the underlying physics being modeled.

  11. Laser Plasma Instability Experiments with KrF Lasers

    National Research Council Canada - National Science Library

    Weaver, J. L; Oh, J; Afeyan, B; Phillips, L; Seely, J; Feldman, U; Brown, C; Karasik, , M; Serlin, V; Aglitskiy, Y; Mostovych, A. N

    2007-01-01

    ...) with a rep-rate system that has a per pulse laser energy well below 1 megajoule. Measurements of LPI using the Nike KrF laser are presented at and above intensities needed for the FTF (Ĩ2x1015 W/cm2...

  12. University of Rochester, Laboratory for Laser Energetics

    Science.gov (United States)

    1987-01-01

    In FY86 the Laboratory has produced a list of accomplishments in which it takes pride. LLE has met every laser-fusion program milestone to date in a program of research for direct-drive ultraviolet laser fusion originally formulated in 1981. LLE scientists authored or co-authored 135 scientific papers during 1985 to 1986. The collaborative experiments with NRL, LANL, and LLNL have led to a number of important ICF results. The cryogenic target system developed by KMS Fusion for LLE will be used in future high-density experiments on OMEGA to demonstrate the compression of thermonuclear fuel to 100 to 200 times that of solid (20 to 40 g/cm) in a test of the direct-drive concept, as noted in the National Academy of Sciences' report. The excellence of the advanced technology efforts at LLE is illustrated by the establishment of the Ultrafast Science Center by the Department of Defense through the Air Force Office of Scientific Research. Research in the Center will concentrate on bridging the gap between high-speed electronics and ultrafast optics by providing education, research, and development in areas critical to future communications and high-speed computer systems. The Laboratory for Laser Energetics continues its pioneering work on the interaction of intense radiation with matter. This includes inertial-fusion and advanced optical and optical electronics research; training people in the technology and applications of high-power, short-pulse lasers; and interacting with the scientific community, business, industry, and government to promote the growth of laser technology.

  13. The recent progress of laser fusion research and future scope

    International Nuclear Information System (INIS)

    Yamanaka, C.

    1986-01-01

    The plasma compression of spherical fuel pellets is performed by irradiation laser beams on the surface of targets. The short wavelength laser or Xray is effective to get high coupling of laser and plasmas without preheating. The implosion uniformity is essentially important to attain the high compression. As for the direct implosion, the multibeam irradiation is necessary to keep a good uniformity of illumination. Extremely high aspect ratio targets are successfully imploded withy neutron yield 10/sup 12/ or more. The shock wave multiplexing is introduced by tailored laser pulses synchronizing with the compression stagnation. Implosion instability seems to be prevented by this scheme. Energy recovering by nuclear fusion is about 10/sup -3/ of the incident laser beam. The indirect implosion using the Cannonball target is very effective to keep the high absorption and the implosion uniformity. However the suprathermal electrons are increased especially at the region of the beam inlet holes. The larger cavity irradiated by the shorter wavelength laser indicates the better results. The Xray conversion by laser is intensively studied using metal targets. Magnetically Insulated Inetially Confined Fusion (MICF) is tested by using CO/sub 2/ lasers. The basic structure of the MICF target is a double shell structure. The irradiation of laser beams through holes of the outer shell produces a toroidal magnetic field due to the current loop produced by the ejected hot electrons. Self organized magnetic field is expected to confine the plasma energy. Plasmas are preserved by the inertial confinement scheme. The experimental results are very interesting to design a hybrid fusion device

  14. Non-Contact Laser Based Ultrasound Evaluation of Canned Foods

    Science.gov (United States)

    Shelton, David

    2005-03-01

    Laser-Based Ultrasound detection was used to measure the velocity of compression waves transmitted through canned foods. Condensed broth, canned pasta, and non-condensed soup were evaluated in these experiments. Homodyne adaptive optics resulted in measurements that were more accurate than the traditional heterodyne method, as well as yielding a 10 dB gain in signal to noise. A-Scans measured the velocity of ultrasound sent through the center of the can and were able to distinguish the quantity of food stuff in its path, as well as distinguish between meat and potato. B-Scans investigated the heterogeneity of the sample’s contents. The evaluation of canned foods was completely non-contact and would be suitable for continuous monitoring in production. These results were verified by conducting the same experiments with a contact piezo transducer. Although the contact method yields a higher signal to noise ratio than the non-contact method, Laser-Based Ultrasound was able to detect surface waves the contact transducer could not.

  15. Shock compression profiles in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  16. A high-power laser system for thermonuclear fusion experiments

    International Nuclear Information System (INIS)

    Azizov, Eh.A.; Ignat'ev, L.P.; Koval'skij, N.G.; Kolesnikov, Yu.A.; Mamzer, A.F.; Pergament, M.I.; Rudnitskij, Yu.P.; Smirnov, G.V.; Yagnov, V.A.; Nikolaevskij, V.G.

    1976-01-01

    A high-power laser system has been designed for an energy output of approximately 3X10 4 J. Neodymium glass was selected based on the level of technical progress, operating experience and the availability of components. The operating performance that has been achieved to date is described. (author)

  17. Laser fusion and precision engineering

    International Nuclear Information System (INIS)

    Nakai, Sadao

    1989-01-01

    The development of laser nuclear fusion energy for attaining the self supply of energy in Japan and establishing the future perspective as the nation is based in the wide fields of high level science and technology. Therefore to its promotion, large expectation is placed as the powerful traction for the development of creative science and technology which are particularly necessary in Japan. The research on laser nuclear fusion advances steadily in the elucidation of the physics of pellet implosion which is its basic concept and compressed plasma parameters. In September, 1986, the number of neutron generation 10 13 , and in October, 1988, the high density compression 600 times as high as solid density have been achieved. Based on these results, now the laser nuclear fusion is in the situation to begin the attainment of ignition condition for nuclear fusion and the realization of break even. The optical components, high power laser technology, fuel pellet production, high resolution measurement, the simulation of implosion using a supercomputer and so on are closely related to precision engineering. In this report, the mechanism of laser nuclear fusion, the present status of its research, and the basic technologies and precision engineering are described. (K.I.)

  18. Sudden viscous dissipation in compressing plasma turbulence

    Science.gov (United States)

    Davidovits, Seth; Fisch, Nathaniel

    2015-11-01

    Compression of a turbulent plasma or fluid can cause amplification of the turbulent kinetic energy, if the compression is fast compared to the turnover and viscous dissipation times of the turbulent eddies. The consideration of compressing turbulent flows in inviscid fluids has been motivated by the suggestion that amplification of turbulent kinetic energy occurred on experiments at the Weizmann Institute of Science Z-Pinch. We demonstrate a sudden viscous dissipation mechanism whereby this amplified turbulent kinetic energy is rapidly converted into thermal energy, which further increases the temperature, feeding back to further enhance the dissipation. Application of this mechanism in compression experiments may be advantageous, if the plasma can be kept comparatively cold during much of the compression, reducing radiation and conduction losses, until the plasma suddenly becomes hot. This work was supported by DOE through contract 67350-9960 (Prime # DOE DE-NA0001836) and by the DTRA.

  19. Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2010-10-01

    We report results on lithium alumino-silicate ion source development in preparation for warmdense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCXII). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ~;;1275 oC, a space-charge-limited Li+ beam current density of J ~;;1 mA/cm2 was obtained. The lifetime of the ion source was ~;;50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 mu s.

  20. Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

    International Nuclear Information System (INIS)

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2010-01-01

    We report results on lithium alumino-silicate ion source development in preparation for warm-dense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCX-II). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ∼1275 C, a space-charge-limited Li + beam current density of J ∼1 mA/cm 2 was obtained. The lifetime of the ion source was ∼50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 (micro) s.

  1. Annual report to the Laser Facility Committee, 1982

    International Nuclear Information System (INIS)

    1982-03-01

    The report covers the work done at, or in association with, the Central Laser Facility during the year April 1981 to March 1982 under the headings; glass laser facility development, gas laser development, laser plasma interactions, transport and particle emission studies, ablative acceleration and compression studies, spectroscopy and XUV lasers, and, theory and computation. Publications based on the work of the facility which have either appeared or been accepted for publication during the year are listed. (U.K.)

  2. Effect of laser shot peening on precipitation hardened aluminum alloy 6061-T6 using low energy laser

    Science.gov (United States)

    Sathyajith, S.; Kalainathan, S.

    2012-03-01

    Mechanical properties of engineering material can be improved by introducing compressive residual stress on the material surface and refinement of their microstructure. Variety of mechanical process such as shot peening, water jet peening, ultrasonic peening, laser shot peening were developed in the last decades on this contrast. Among these, lasers shot peening emerged as a novel industrial treatment to improve the crack resistance of turbine blades and the stress corrosion cracking (SCC) of austenic stainless steel in power plants. In this study we successfully performed laser shot peening on precipitation hardened aluminum alloy 6061-T6 with low energy (300 mJ, 1064 nm) Nd:YAG laser using different pulse densities of 22 pulses/mm 2 and 32 pulses/mm 2. Residual stress evaluation based on X-ray diffraction sin 2 ψ method indicates a maximum of 190% percentage increase on surface compressive stress. Depth profile of micro-hardness shows the impact of laser generated shock wave up to 1.2 mm from the surface. Apart from that, the crystalline size and micro-strain on the laser shot peened surfaces have been investigated and compared with the unpeened surface using X-ray diffraction in conjunction with line broadening analysis through the Williamson-Hall plot.

  3. Laser fusion experiments at LLL

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstrom, H.G.

    1980-06-16

    These notes present the experimental basis and status for laser fusion as developed at LLL. Two other chapters, one authored by K.A. Brueckner and the other by C. Max, present the theoretical implosion physics and laser plasma interaction physics. The notes consist of six sections. The first is an introductory section which provides some of the history of inertial fusion and a simple explanation of the concepts involved. The second section presents an extensive discussion of diagnostic instrumentation used in the LLL Laser Fusion Program. The third section is a presentation of laser facilities and capabilities at LLL. The purpose here is to define capability, not to derive how it was obtained. The fourth and fifth sections present the experimental data on laser-plasma interaction and implosion physics. The last chapter is a short projection of the future.

  4. Laser fusion experiments at LLL

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.

    1980-01-01

    These notes present the experimental basis and status for laser fusion as developed at LLL. Two other chapters, one authored by K.A. Brueckner and the other by C. Max, present the theoretical implosion physics and laser plasma interaction physics. The notes consist of six sections. The first is an introductory section which provides some of the history of inertial fusion and a simple explanation of the concepts involved. The second section presents an extensive discussion of diagnostic instrumentation used in the LLL Laser Fusion Program. The third section is a presentation of laser facilities and capabilities at LLL. The purpose here is to define capability, not to derive how it was obtained. The fourth and fifth sections present the experimental data on laser-plasma interaction and implosion physics. The last chapter is a short projection of the future

  5. A painful, never ending story: older women's experiences of living with an osteoporotic vertebral compression fracture.

    Science.gov (United States)

    Svensson, H K; Olofsson, E H; Karlsson, J; Hansson, T; Olsson, L-E

    2016-05-01

    Vertebral compression fractures (VCF) cause pain and decreased physical ability, with no known well-established treatment. The aim of this study was to illuminate the experience of living with a VCF. The results show that fear and concerns are a major part of daily life. The women's initial contact with health-care providers should focus on making them feel acknowledged by offering person-centered and tailored support. In the past decade, osteoporotic-related fractures have become an increasingly common and costly public health problem worldwide. Vertebral compression fracture (VCF) is the second most common osteoporotic fracture, and patients with VCF describe an abrupt descent into disability, with a subsequent desire to regain independence in everyday life; however, little is known of their situation. The aim of this study was to illuminate the lived experience of women with an osteoporotic VCF. Ten women were interviewed during 2012-2013, starting with an open-ended question: could you tell me what it is like to live with a vertebral compression fracture? The verbatim transcribed interviews were analyzed using a phenomenological hermeneutical approach. The narrative provided descriptions of living in turmoil and chaos, unable to find stability in their life with little improvement regarding pain and physical function. Shifts from periods of constant pain to periods of fear of constant pain created a loss of confidence and an increased sense of confinement. The structural analysis revealed fear and concerns as the most prominent experience building on five themes: struggling to understand a deceiving body, breakthrough pain fueling fear, fearing a trajectory into isolation, concerns of dependency, and fearing an uncertain future. Until researchers find a successful prevention or medical/surgical treatment for osteoporotic VCFs, health-care providers and society abandon these women to remain in a painful and never ending story.

  6. Few-cycle high energy mid-infrared pulse from Ho:YLF laser

    International Nuclear Information System (INIS)

    Murari, Krishna

    2017-04-01

    Over the past decade, development of high-energy ultrafast laser sources has led to important breakthroughs in attoscience and strong-field physics study in atoms and molecules. Coherent pulse synthesis of few-cycle high-energy laser pulse is a promising tool to generate isolated attosecond pulses via high harmonics generation (HHG). An effective way to extend the HHG cut-off energy to higher values is making use of long mid-infrared (MIR) driver wavelength, as the ponderomotive potential scales quadratically with wavelength. If properly scaled in energy to multi-mJ level and few-cycle duration, such pulses provide a direct path to intriguing attoscience experiments in gases and solids, which even permit the realization of bright coherent table-top HHG sources in the water-window and keV X-ray region. However, the generation of high-intensity long-wavelength MIR pulses has always remained challenging, in particular starting from high-energy picosecond 2-μm laser driver, that is suitable for further energy scaling of the MIR pulses to multi-mJ energies by utilizing optical parametric amplifiers (OPAs). In this thesis, a front-end source for such MIR OPA is presented. In particular, a novel and robust strong-field few-cycle 2-μm laser driver directly from picosecond Ho:YLF laser and utilizing Kagome fiber based compression is presented. We achieved: a 70-fold compression of 140-μJ, 3.3-ps pulses from Ho:YLF amplifier to 48 fs with 11 μJ energy. The work presented in this thesis demonstrates a straightforward path towards generation of few-cycle MIR pulses and we believe that in the future the ultrafast community will benefit from this enabling technology. The results are summarized in mainly four parts: The first part is focused on the development of a 2-μm, high-energy laser source as the front-end. Comparison of available technology in general and promising gain media at MIR wavelength are discussed. Starting from the basics of an OPA, the design criteria

  7. Few-cycle high energy mid-infrared pulse from Ho:YLF laser

    Energy Technology Data Exchange (ETDEWEB)

    Murari, Krishna

    2017-04-15

    Over the past decade, development of high-energy ultrafast laser sources has led to important breakthroughs in attoscience and strong-field physics study in atoms and molecules. Coherent pulse synthesis of few-cycle high-energy laser pulse is a promising tool to generate isolated attosecond pulses via high harmonics generation (HHG). An effective way to extend the HHG cut-off energy to higher values is making use of long mid-infrared (MIR) driver wavelength, as the ponderomotive potential scales quadratically with wavelength. If properly scaled in energy to multi-mJ level and few-cycle duration, such pulses provide a direct path to intriguing attoscience experiments in gases and solids, which even permit the realization of bright coherent table-top HHG sources in the water-window and keV X-ray region. However, the generation of high-intensity long-wavelength MIR pulses has always remained challenging, in particular starting from high-energy picosecond 2-μm laser driver, that is suitable for further energy scaling of the MIR pulses to multi-mJ energies by utilizing optical parametric amplifiers (OPAs). In this thesis, a front-end source for such MIR OPA is presented. In particular, a novel and robust strong-field few-cycle 2-μm laser driver directly from picosecond Ho:YLF laser and utilizing Kagome fiber based compression is presented. We achieved: a 70-fold compression of 140-μJ, 3.3-ps pulses from Ho:YLF amplifier to 48 fs with 11 μJ energy. The work presented in this thesis demonstrates a straightforward path towards generation of few-cycle MIR pulses and we believe that in the future the ultrafast community will benefit from this enabling technology. The results are summarized in mainly four parts: The first part is focused on the development of a 2-μm, high-energy laser source as the front-end. Comparison of available technology in general and promising gain media at MIR wavelength are discussed. Starting from the basics of an OPA, the design criteria

  8. Dosimetry of laser-accelerated electron beams used for in vitro cell irradiation experiments

    International Nuclear Information System (INIS)

    Richter, C.; Kaluza, M.; Karsch, L.; Schlenvoigt, H.-P.; Schürer, M.; Sobiella, M.; Woithe, J.; Pawelke, J.

    2011-01-01

    The dosimetric characterization of laser-accelerated electrons applied for the worldwide first systematic radiobiological in vitro cell irradiation will be presented. The laser-accelerated electron beam at the JeTi laser system has been optimized, monitored and controlled in terms of dose homogeneity, stability and absolute dose delivery. A combination of different dosimetric components were used to provide both an online beam as well as dose monitoring and a precise absolute dosimetry. In detail, the electron beam was controlled and monitored by means of an ionization chamber and an in-house produced Faraday cup for a defined delivery of the prescribed dose. Moreover, the precise absolute dose delivered to each cell sample was determined by an radiochromic EBT film positioned in front of the cell sample. Furthermore, the energy spectrum of the laser-accelerated electron beam was determined. As presented in a previous work of the authors, also for laser-accelerated protons a precise dosimetric characterization was performed that enabled initial radiobiological cell irradiation experiments with laser-accelerated protons. Therefore, a precise dosimetric characterization, optimization and control of laser-accelerated and therefore ultra-short pulsed, intense particle beams for both electrons and protons is possible, allowing radiobiological experiments and meeting all necessary requirements like homogeneity, stability and precise dose delivery. In order to fulfill the much higher dosimetric requirements for clinical application, several improvements concerning, i.e., particle energy and spectral shaping as well as patient safety are necessary.

  9. First Octahedral Spherical Hohlraum Energetics Experiment at the SGIII Laser Facility

    Science.gov (United States)

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xufei; Ren, Guoli; Cao, Hui; Li, Shu; Lan, Ke; Liu, Jie; Li, Yongsheng; Li, Sanwei; Guo, Liang; Liu, Yonggang; Yang, Dong; Jiang, Xiaohua; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Wang, Zhebin; Deng, Keli; Wang, Qiangqiang; Deng, Bo; Wang, Feng; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Gu, Qianqian; He, Zhibing; Du, Kai; Deng, Xuewei; Zhou, Wei; Wang, Liquan; Huang, Xiaoxia; Wang, Yuancheng; Hu, Dongxia; Zheng, Kuixing; Zhu, Qihua; Ding, Yongkun

    2018-04-01

    The first octahedral spherical hohlraum energetics experiment is accomplished at the SGIII laser facility. For the first time, the 32 laser beams are injected into the octahedral spherical hohlraum through six laser entrance holes. Two techniques are used to diagnose the radiation field of the octahedral spherical hohlraum in order to obtain comprehensive experimental data. The radiation flux streaming out of laser entrance holes is measured by six flat-response x-ray detectors (FXRDs) and four M -band x-ray detectors, which are placed at different locations of the SGIII target chamber. The radiation temperature is derived from the measured flux of FXRD by using the blackbody assumption. The peak radiation temperature inside hohlraum is determined by the shock wave technique. The experimental results show that the octahedral spherical hohlraum radiation temperature is in the range of 170-182 eV with drive laser energies of 71 kJ to 84 kJ. The radiation temperature inside the hohlraum determined by the shock wave technique is about 175 eV at 71 kJ. For the flat-top laser pulse of 3 ns, the conversion efficiency of gas-filled octahedral spherical hohlraum from laser into soft x rays is about 80% according to the two-dimensional numerical simulation.

  10. Shock-timing experiments for Inertial Confinement Fusion

    International Nuclear Information System (INIS)

    Debras, G.

    2012-01-01

    The Laser Megajoule (LMJ), which should achieve energy gain in an indirect drive inertial confinement fusion configuration, is being built in France by the CEA (Commissariat a l'Energie Atomique et aux Energies Alternatives). To achieve thermonuclear ignition, the compression of a spherical target will have to be controlled by a series of accurately timed centripetal shocks, with a finely tuned level. A first experiment, performed in 2010 on the LIL (Ligne d'Integration Laser) facility at CEA, has allowed us to study the coalescence of two planar shocks in an indirectly-driven sample of polystyrene, within the framework of shock timing. The main objectives were to validate the experimental concept and the numerical simulations, as a proof-of-principle for future shock-timing campaigns. The main diagnostics used for this study are VISAR (Velocity Interferometer System for Any Reflection) and an optical shock breakout diagnostic, taking into account optical perturbations caused by X-rays. In another experiment, conducted on the LULI (Laboratoire pour l'Utilisation des Lasers Intenses) laser facility in 2010, we studied the timing of two planar directly-driven shocks using the same diagnostics. This latter study is related to the shock ignition concept, with the long-term perspective of energy production. This thesis presents these two experiments and their results. (author) [fr

  11. Laser cost experience and estimation

    International Nuclear Information System (INIS)

    Shofner, F.M.; Hoglund, R.L.

    1977-01-01

    This report addresses the question of estimating the capital and operating costs for LIS (Laser Isotope Separation) lasers, which have performance requirements well beyond the state of mature art. This question is seen with different perspectives by political leaders, ERDA administrators, scientists, and engineers concerned with reducing LIS to economically successful commercial practice, on a timely basis. Accordingly, this report attempts to provide ''ballpark'' estimators for capital and operating costs and useful design and operating information for lasers based on mature technology, and their LIS analogs. It is written very basically and is intended to respond about equally to the perspectives of administrators, scientists, and engineers. Its major contributions are establishing the current, mature, industrialized laser track record (including capital and operating cost estimators, reliability, types of application, etc.) and, especially, evolution of generalized estimating procedures for capital and operating cost estimators for new laser design

  12. Advanced-laser development for isotope separation. Final report

    International Nuclear Information System (INIS)

    1983-06-01

    To address a number of the issues associated with lasers appropriate for both atomic vapor and molecular laser enrichment schemes, MSNW developed pertinent technologies on two test devices. These were a high pulse rate, 100 watt excimer laser named Mistral, and a 20 watt copper-vapor laser (CVL). Mistral is a closed-loop, 100 W, kilohertz rare-gas halide laser system. The first half of the Mistral effort dealt with the study of gas flow and acoustic effects in high PRF rare-gas halide lasers. In burst-mode operation, 1250 Hz operation was demonstrated, the effects on flow quality of acoustic dampers were measured, and gas clearing factors of 2.5 at 1 kHz were demonstrated. The second half of the Mistral program dealt with extending the run time capability of the laser. This effort culminated with the continuous operation of Mistral for almost eight hours at 500 ppS, producing over 50 mJ/pulse at 308 nm on a single fill of XeCl gas mixture. At the end of the program, the effectiveness of using magnetic pulse compression in the modulator circuit of a copper-vapor laser (CVL) was also verified. The magnetic switching/pulse compression scheme as used on both the CVL and Mistral greatly extends thyratron lifetime

  13. Laser-induced generation of pure tensile stresses

    International Nuclear Information System (INIS)

    Niemz, M.H.; Lin, C.P.; Pitsillides, C.; Cui, J.; Doukas, A.G.; Deutsch, T.F.

    1997-01-01

    While short compressive stresses can readily be produced by laser ablation, the generation of pure tensile stresses is more difficult. We demonstrate that a 90 degree prism made of polyethylene can serve to produce short and pure tensile stresses. A compressive wave is generated by ablating a thin layer of strongly absorbing ink on one surface of the prism with a Q-switched frequency-doubled Nd:YAG laser. The compressive wave driven into the prism is reflected as a tensile wave by the polyethylene-air interface at its long surface. The low acoustic impedance of polyethylene makes it ideal for coupling tensile stresses into liquids. In water, tensile stresses up to -200bars with a rise time of the order of 20 ns and a duration of 100 ns are achieved. The tensile strength of water is determined for pure tensile stresses lasting for 100 ns only. The technique has potential application in studying the initiation of cavitation in liquids and in comparing the effect of compressive and tensile stress transients on biological media. copyright 1997 American Institute of Physics

  14. Shock Compression of Liquid Noble Gases to Multi-Mbar Pressures

    Science.gov (United States)

    Root, Seth

    2011-10-01

    The high pressure - high temperature behavior of noble gases is of considerable interest because of their use in z-pinch liners for fusion studies and for understanding astrophysical and planetary evolution. However, our understanding of the equation of state (EOS) of the noble gases at extreme conditions is limited. A prime example of this is the liquid xenon Hugoniot. Previous EOS models rapidly diverged on the Hugoniot above 1 Mbar because of differences in the treatment of the electronic contribution to the free energy. Similar divergences are observed for krypton EOS. Combining shock compression experiments and density functional theory (DFT) simulations, we can determine the thermo-physical behavior of matter under extreme conditions. The experimental and DFT results have been instrumental to recent developments in planetary astrophysics and inertial confinement fusion. Shock compression experiments are performed using Sandia's Z-Accelerator to determine the Hugoniot of liquid xenon and krypton in the Mbar regime. Under strong pressure, krypton and xenon undergo an insulator to metal transition. In the metallic state, the shock front becomes reflective allowing for a direct measurement of the sample's shock velocity using laser interferometry. The Hugoniot state is determined using a Monte Carlo analysis method that accounts for systematic error in the standards and for correlations. DFT simulations at these extreme conditions show good agreement with the experimental data - demonstrating the attention to detail required for dealing with elements with relativistic core states and d-state electrons. The results from shock compression experiments and DFT simulations are presented for liquid xenon to 840 GPa and for liquid krypton to 800 GPa, decidedly increasing the range of known behavior of both gases. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company

  15. Intra-pulse Cavity Enhanced Measurements of Carbon Monoxide in a Rapid Compression Machine

    KAUST Repository

    Nasir, Ehson Fawad

    2018-05-07

    A laser absorption sensor for carbon monoxide concentration was developed for combustion studies in a rapid compression machine using a pulsed quantum cascade laser near 4.89 μm. Cavity enhancement reduced minimum detection limit down to 2.4 ppm at combustion relevant conditions. Off-axis alignment and rapid intra-pulse down-chirp resulted in effective suppression of cavity noise.

  16. Obtaining attosecond x-ray pulses using a self-amplified spontaneous emission free electron laser

    Directory of Open Access Journals (Sweden)

    A. A. Zholents

    2005-05-01

    Full Text Available We describe a technique for the generation of a solitary attosecond x-ray pulse in a free-electron laser (FEL, via a process of self-amplified spontaneous emission. In this method, electrons experience an energy modulation upon interacting with laser pulses having a duration of a few cycles within single-period wiggler magnets. Two consecutive modulation sections, followed by compression in a dispersive section, are used to obtain a single, subfemtosecond spike in the electron peak current. This region of the electron beam experiences an enhanced growth rate for FEL amplification. After propagation through a long undulator, this current spike emits a ∼250   attosecond x-ray pulse whose intensity dominates the x-ray emission from the rest of the electron bunch.

  17. Integrated IoT technology in industrial lasers for the improved user experience

    Science.gov (United States)

    Ding, Jianwu; Liu, Jinhui

    2018-02-01

    The end users' biggest concern for any industrial equipment is the reliability and the service down-time. This is especially true for industrial lasers as they are typically used in fully or semi- automated processes. Here we demonstrate how to use the integrated Internet of Things (IoT) technology in industrial lasers to address the reliability and the service down-time so to improve end users' experience.

  18. Advanced lasers for fusion

    International Nuclear Information System (INIS)

    Krupke, W.F.; George, E.V.; Haas, R.A.

    1979-01-01

    Laser drive systems' performance requirements for fusion reactors are developed following a review of the principles of inertial confinement fusion and of the technical status of fusion research lasers (Nd:glass; CO 2 , iodine). These requirements are analyzed in the context of energy-storing laser media with respect to laser systems design issues: optical damage and breakdown, medium excitation, parasitics and superfluorescence depumping, energy extraction physics, medium optical quality, and gas flow. Three types of energy-storing laser media of potential utility are identified and singled out for detailed review: (1) Group VI atomic lasers, (2) rare earth solid state hybrid lasers, and (3) rare earth molecular vapor lasers. The use of highly-radiative laser media, particularly the rare-gas monohalide excimers, are discussed in the context of short pulse fusion applications. The concept of backward wave Raman pulse compression is considered as an attractive technique for this purpose. The basic physics and device parameters of these four laser systems are reviewed and conceptual designs for high energy laser systems are presented. Preliminary estimates for systems efficiencies are given. (Auth.)

  19. PRK by Er:YAG laser: in-vitro studies and first in-vivo experiences

    Science.gov (United States)

    Steiner, Rudolf W.; Leiacker, Richard; Russ, Detlef; Seiler, Theo

    1996-01-01

    Photorefractive keratectomy (PRK) is usually performed by an excimer laser at 193 nm wavelength. Ablatio of corneal tissue is, however, not only possible in the UV region of the optical spectrum but also in the IR where water is an excellent absorber. Therefore, an Er:YAG laser was used at 2.94 micrometer wavelength as an alternative laser light source to perform in vitro studies of corneal ablation and also first clinical experiments to correct myopia of patients with blind eyes.

  20. EXPERIENCE WITH ROBOTIC LUMЕNIS CO LASER IN ENDOSCOPIC LARYNGEAL SURGERY

    Directory of Open Access Journals (Sweden)

    E. N. Novozhilova

    2014-01-01

    Full Text Available  2 The paper describes the first experience in using robotic CO laser at the Department of Head and Neck Tumors, Moscow City Cancer Hospital Sixty-Two. With advances in endoscopic techniques and anesthesiology, there have been new possibilities of usingdirect (rigid larygoscopy in conjunction with laser systems.The Lumеnis laser assembly consists of three interconnected components: a videocamera, an operating microscope, and directly CO laser. It includes a computer system that sets a program to perform an operation.The heart of the laser system is a scanning Digital Acu Blade micromanipulator. This unique assembly makes itpossible to control the area and depth of incision, to cut intricate shapes in relation to the surface anatomy, and to precisely control ablation and hemostasis. The effect of tissue carbonization during surgery is minimal at the expense of the physical characteristics and different modes of radiation. It is noted that this system allows organ-sparing treatment in cancer patients and their prompt rehabilitation after surgical interventions.

  1. Multi-peta-watt laser performances

    International Nuclear Information System (INIS)

    Reichart, A.; Blanchot, N.; Nicolaizeau, M.; Ribeyre, X.; Bettinger, A.

    2000-01-01

    A multi-Peta-watt laser inside the 'Ligne d'integration laser' building is studied. We present simulations of the different amplification stages to reach broadband 10 kJ pulses in order to obtain a multi-Peta-watt laser beam. The results for preamplifier and power amplifier are detailed. Challenges of a multi-Peta-watt system are to increase the limit of compressed energy an order of magnitude, to perform a focal spot around 100 μm for Fast Ignitor applications, and to provide a temporal contrast better than 10 10 , for X-ray laser and plasma interaction applications. These first 1-D calculations are helpful for the design of a multi-Peta-watt laser. (authors)

  2. Two-way laser ranging and time transfer experiments between LOLA and an Earth-based satellite laser ranging station

    Science.gov (United States)

    Mao, D.; Sun, X.; Neumann, G. A.; Barker, M. K.; Mazarico, E. M.; Hoffman, E.; Zagwodzki, T. W.; Torrence, M. H.; Mcgarry, J.; Smith, D. E.; Zuber, M. T.

    2017-12-01

    Satellite Laser Ranging (SLR) has established time-of-flight measurements with mm precision to targets orbiting the Earth and the Moon using single-ended round-trip laser ranging to passive optical retro-reflectors. These high-precision measurements enable advances in fundamental physics, solar system dynamics. However, the received signal strength suffers from a 1/R4 decay, which makes it impractical for measuring distances beyond the Moon's orbit. On the other hand, for a two-way laser transponder pair, where laser pulses are both transmitted to and received from each end of the laser links, the signal strength at both terminals only decreases by 1/R2, thus allowing a greater range of distances to be covered. The asynchronous transponder concept has been previously demonstrated by a test in 2005 between the Mercury Laser Altimeter (MLA) aboard the MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft and NASA's Goddard Geophysical and Astronomical Observatory (GGAO) at a distance of ˜0.16 AU. In October 2013, regular two-way transponder-type range measurements were obtained over 15 days between the Lunar Laser Communication Demonstration (LLCD) aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft and NASA's ground station at White Sands, NM. The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) provides us a unique capability to test time-transfer beyond near Earth orbit. Here we present results from two-way transponder-type experiments between LOLA and GGAO conducted in March 2014 and 2017. As in the time-transfer by laser link (T2L2) experiments between a ground station and an earth-orbiting satellite, LOLA and GGAO ranged to each other simultaneously in these two-way tests at lunar distance. We measured the time-of-flight while cross-referencing the spacecraft clock to the ground station time. On May 4th, 2017, about 20 minutes of two-way measurements were collected. The

  3. Confined compression and torsion experiments on a pHEMA gel in various bath concentrations.

    Science.gov (United States)

    Roos, Reinder W; Petterson, Rob; Huyghe, Jacques M

    2013-06-01

    The constitutive behaviour of cartilaginous tissue is the result of complex interaction between electrical, chemical and mechanical forces. Electrostatic interactions between fixed charges and mobile ions are usually accounted for by means of Donnan osmotic pressure. Recent experimental data show, however, that the shear modulus of articular cartilage depends on ionic concentration even if the strain is kept constant. Poisson-Boltzmann simulations suggest that this dependence is intrinsic to the double-layer around the proteoglycan chains. In order to verify this premise, this study measures whether--at a given strain--this ionic concentration-dependent shear modulus is present in a polymerized hydroxy-ethyl-methacrylate gel or not. A combined 1D confined compression and torque experiment is performed on a thin cylindrical hydrogel sample, which is brought in equilibrium with, respectively, 1, 0.1 and 0.03 M NaCl. The sample was placed in a chamber that consists of a stainless steel ring placed on a sintered glass filter, and on top a sintered glass piston. Stepwise ionic loading was cascaded by stepwise 1D compression, measuring the total stress after equilibration of the sample. In addition, a torque experiment was interweaved by applying a harmonic angular displacement and measuring the torque, revealing the relation between aggregate shear modulus and salt concentration at a given strain.

  4. Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression

    Science.gov (United States)

    Douglas, David R [Newport News, VA; Tennant, Christopher D [Williamsburg, VA

    2012-07-10

    A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

  5. Theory and Simulation of an Inverse Free Electron Laser Experiment

    Science.gov (United States)

    Guo, S. K.; Bhattacharjee, A.; Fang, J. M.; Marshall, T. C.

    1996-11-01

    An experimental demonstration of the acceleration of electrons using a high power CO2 laser in an inverse free electron laser (IFEL) is underway at the Brookhaven National Laboratory. This experiment has generated data, which we are attempting to simulate. Included in our studies are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge (which is significant at lower laser power); energy-spread of the electrons; arbitrary wiggler field profile; and slippage. Two types of wiggler profile have been considered: a linear taper of the period, and a step-taper of the period (the period is ~ 3cm, the field is ~ 1T, and the wiggler length is 47cm). The energy increment of the electrons ( ~ 1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (40MeV). For laser power ~ 0.5GW, the predictions of the simulations are in good accord with experimental results. A matter currently under study is the discrepancy between theory and observations for the electron energy distribution observed at the end of the IFEL. This work is supported by the Department of Energy.

  6. High-power ultrashort fiber laser for solar cells micromachining

    Science.gov (United States)

    Lecourt, J.-B.; Duterte, C.; Liegeois, F.; Lekime, D.; Hernandez, Y.; Giannone, D.

    2012-02-01

    We report on a high-power ultra-short fiber laser for thin film solar cells micromachining. The laser is based on Chirped Pulse Amplification (CPA) scheme. The pulses are stretched to hundreds of picoseconds prior to amplification and can be compressed down to picosecond at high energy. The repetition rate is adjustable from 100 kHz to 1 MHz and the optical average output power is close to 13 W (before compression). The whole setup is fully fibred, except the compressor achieved with bulk gratings, resulting on a compact and reliable solution for cold ablation.

  7. FY07 LDRD Final Report Precision, Split Beam, Chirped-Pulse, Seed Laser Technology

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, J W; Messerly, M J; Phan, H H; Crane, J K; Beach, R J; Siders, C W; Barty, C J

    2009-11-12

    The goal of this LDRD ER was to develop a robust and reliable technology to seed high-energy laser systems with chirped pulses that can be amplified to kilo-Joule energies and recompressed to sub-picosecond pulse widths creating extremely high peak powers suitable for petawatt class physics experiments. This LDRD project focused on the development of optical fiber laser technologies compatible with the current long pulse National Ignition Facility (NIF) seed laser. New technologies developed under this project include, high stability mode-locked fiber lasers, fiber based techniques for reduction of compressed pulse pedestals and prepulses, new compact stretchers based on chirped fiber Bragg gratings (CFBGs), new techniques for manipulation of chirped pulses prior to amplification and new high-energy fiber amplifiers. This project was highly successful and met virtually all of its goals. The National Ignition Campaign has found the results of this work to be very helpful. The LDRD developed system is being employed in experiments to engineer the Advanced Radiographic Capability (ARC) front end and the fully engineered version of the ARC Front End will employ much of the technology and techniques developed here.

  8. Research on imploded plasma heating by short pulse laser for fast ignition

    International Nuclear Information System (INIS)

    Kodama, R.; Kitagawa, Y.; Mima, K.

    2001-01-01

    Since the peta watt module (PWM) laser was constructed in 1995, investigated are heating processes of imploded plasmas by intense short pulse lasers. In order to heat the dense plasma locally, a heating laser pulse should be guided into compressed plasmas as deeply as possible. Since the last IAEA Fusion Conference, the feasibility of fast ignition has been investigated by using the short pulse GEKKO MII glass laser and the PWM laser with GEKKO XII laser. We found that relativistic electrons are generated efficiently in a preformed plasma to heat dense plasmas. The coupling efficiency of short pulse laser energy to a solid density plasma is 40% when no plasmas are pre-formed, and 20% when a large scale plasma is formed by a long pulse laser pre-irradiation. The experimental results are confirmed by numerical simulations using the simulation code 'MONET' which stands for the Monte-Carlo Electron Transport code developed at Osaka. In the GEKKO XII and PWM laser experiments, intense heating pulses are injected into imploded plasmas. As a result of the injection of heating pulse, it is found that high energy electrons and ions could penetrate into imploded core plasmas to enhance neutron yield by factor 3∼5. (author)

  9. High Pressure In Situ X-ray Diffraction Study of MnO to 120 GPa and Comparison with Shock Compression Experiment

    Science.gov (United States)

    Yagi, Takehiko; Kondo, Tadashi; Syono, Yasuhiko

    1997-07-01

    In order to clarify the nature of the phase transformation in MnO observed at around 90 GPa by shock compression experiment (Syono et al., this symposium), high pressure in situ x-ray experiments were carried out up to 120 GPa. Powdered sample was directly compressed in Mao-Bell type diamond anvil and x-ray experiments were carried out using angle dispersive technique by combining synchrotron radiation and imaging plate detector. Distortion of the B1 structured phase into hexagonal unit cell was observed from 25-40 GPa, which continues to increase up to 90 GPa. At around 90 GPa, discontinuous change of the diffraction was observed. This new phase cannot be explained by a simple B2 structure and the analysis of this phase is in progress. This high pressure phase has metallic appearance, which reverses to transparent MnO on release of pressure.

  10. Status of the free-electron laser experiment at Los Alamos

    International Nuclear Information System (INIS)

    Warren, R.W.; Brau, C.A.; Newnam, B.E.; Stein, W.E.; Winston, J.G.; Young, L.M.

    1981-01-01

    Main design parameters are presented for the accelerator, the laser, and the wiggler. Four sections are presented that discuss unusual or different features in the design, construction, alignment, and diagnostic parts of the experiment. Up-to-date performance characteristics of the components are described

  11. Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser

    International Nuclear Information System (INIS)

    Savelyev, Evgeny; Boll, Rebecca; Bomme, Cedric; Schirmel, Nora; Redlin, Harald

    2017-01-01

    In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene C 6 H 3 F 2 I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. Here, we discuss in detail the necessary data analysis steps and describe the origin of the time-dependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment.

  12. Novel active signal compression in low-noise analog readout at future X-ray FEL facilities

    Science.gov (United States)

    Manghisoni, M.; Comotti, D.; Gaioni, L.; Lodola, L.; Ratti, L.; Re, V.; Traversi, G.; Vacchi, C.

    2015-04-01

    This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 μm. This work has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare (INFN), Italy.

  13. DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS

    International Nuclear Information System (INIS)

    Bieniosek, F.M.; Henestroza, E.; Lidia, S.; Ni, P.A.

    2010-01-01

    Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30-mA K + beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multi-channel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (VISAR), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.

  14. Laser induced fluorescence thermometry (LIF-T) as a non-invasive temperature measurement technique for thermal hydraulic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Strack, J.; Leung, K.; Walker, A., E-mail: strackj@mcmaster.ca [McMaster Univ., Hamilton, ON (Canada)

    2014-07-01

    Laser induced fluorescence (LIF) is an experimental technique whereby a scalar field in a fluid system is measured optically from the fluorescence intensity of a tracer dye following excitation by laser light. For laser induced fluorescence thermometry (LIF-T), a temperature sensitive dye is used. Through the use of a temperature sensitive tracer dye, sheet laser optics, optical filters, and photography, a 2D temperature field can be measured non-invasively. An experiment to test the viability of using LIF-T for macroscopic thermal hydraulic experiments was developed and tested. A reference calibration curve to relate fluorescence measurements to temperature is presented. (author)

  15. HVS-based medical image compression

    Energy Technology Data Exchange (ETDEWEB)

    Kai Xie [Institute of Image Processing and Pattern Recognition, Shanghai Jiaotong University, 200030 Shanghai (China)]. E-mail: xie_kai2001@sjtu.edu.cn; Jie Yang [Institute of Image Processing and Pattern Recognition, Shanghai Jiaotong University, 200030 Shanghai (China); Min Zhuyue [CREATIS-CNRS Research Unit 5515 and INSERM Unit 630, 69621 Villeurbanne (France); Liang Lixiao [Institute of Image Processing and Pattern Recognition, Shanghai Jiaotong University, 200030 Shanghai (China)

    2005-07-01

    Introduction: With the promotion and application of digital imaging technology in the medical domain, the amount of medical images has grown rapidly. However, the commonly used compression methods cannot acquire satisfying results. Methods: In this paper, according to the existed and stated experiments and conclusions, the lifting step approach is used for wavelet decomposition. The physical and anatomic structure of human vision is combined and the contrast sensitivity function (CSF) is introduced as the main research issue in human vision system (HVS), and then the main designing points of HVS model are presented. On the basis of multi-resolution analyses of wavelet transform, the paper applies HVS including the CSF characteristics to the inner correlation-removed transform and quantization in image and proposes a new HVS-based medical image compression model. Results: The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging (MRI). At the same bit rate, the performance of SPIHT, with respect to the PSNR metric, is significantly higher than that of our algorithm. But the visual quality of the SPIHT-compressed image is roughly the same as that of the image compressed with our approach. Our algorithm obtains the same visual quality at lower bit rates and the coding/decoding time is less than that of SPIHT. Conclusions: The results show that under common objective conditions, our compression algorithm can achieve better subjective visual quality, and performs better than that of SPIHT in the aspects of compression ratios and coding/decoding time.

  16. HVS-based medical image compression

    International Nuclear Information System (INIS)

    Kai Xie; Jie Yang; Min Zhuyue; Liang Lixiao

    2005-01-01

    Introduction: With the promotion and application of digital imaging technology in the medical domain, the amount of medical images has grown rapidly. However, the commonly used compression methods cannot acquire satisfying results. Methods: In this paper, according to the existed and stated experiments and conclusions, the lifting step approach is used for wavelet decomposition. The physical and anatomic structure of human vision is combined and the contrast sensitivity function (CSF) is introduced as the main research issue in human vision system (HVS), and then the main designing points of HVS model are presented. On the basis of multi-resolution analyses of wavelet transform, the paper applies HVS including the CSF characteristics to the inner correlation-removed transform and quantization in image and proposes a new HVS-based medical image compression model. Results: The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging (MRI). At the same bit rate, the performance of SPIHT, with respect to the PSNR metric, is significantly higher than that of our algorithm. But the visual quality of the SPIHT-compressed image is roughly the same as that of the image compressed with our approach. Our algorithm obtains the same visual quality at lower bit rates and the coding/decoding time is less than that of SPIHT. Conclusions: The results show that under common objective conditions, our compression algorithm can achieve better subjective visual quality, and performs better than that of SPIHT in the aspects of compression ratios and coding/decoding time

  17. Annual report to the Laser Facility Committee 1979

    International Nuclear Information System (INIS)

    1979-03-01

    The report covers the work done at the Central Laser Facility, Rutherford Laboratory during the year preceding 31 March 1979. Preliminary work already undertaken on the upgrade of the glass laser and target areas consisting of the relocation of the two beam target chamber and tests on phosphate glass and also the completion of the electron beam generator for use by researchers on high power gas laser systems, are described. Work of the groups using the glass laser facility are considered under the headings; glass laser development, gas laser development, laser plasma interactions, transport and particle emission, ablative compression studies, atomic and radiation physics, XUV lasers, theory and computation. (U.K.)

  18. Modeling Laser and e-Beam Generated Plasma-Plume Experiments Using LASNEX

    CERN Document Server

    Ho, D

    1999-01-01

    The hydrodynamics code LASNEX is used to model the laser and e-beam generated plasma-plume experiments. The laser used has a wavelength of 1 (micro)m and the FWHM spot size is 1 mm. The total laser energy is 160 mJ. The simulation shows that the plume expands at a velocity of about 6 cm/(micro)s. The e-beam generated from the Experimental Test Accelerator (ETA) has 5.5 MeV and FWHM spot size ranges from 2 to 3.3 mm. From the simulations, the plasma plume expansion velocity ranges from about 3 to 6 mm/(micro)s and the velocity increases with decreasing spot size. All the simulation results reported here are in close agreement with experimental data.

  19. DNABIT Compress – Genome compression algorithm

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that “DNABIT Compress” algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases. PMID:21383923

  20. Detailed experimental study of a highly compressible supersonic turbulent plane mixing layer and comparison with most recent DNS results: “Towards an accurate description of compressibility effects in supersonic free shear flows”

    International Nuclear Information System (INIS)

    Barre, S.; Bonnet, J.P.

    2015-01-01

    Highlights: • We performed a careful experiment on a highly compressible mixing layer. • We validated the most recent DNS with the present results. • We discuss some aspects of the thermodynamics of the turbulent flow. • We performed a comparison between a computed and a measured turbulent kinetic energy budget. - Abstract: A compressible supersonic mixing layer at convective Mach number (Mc) equal to 1 has been studied experimentally in a dual stream supersonic/subsonic wind-tunnel. Laser Doppler Velocimetry (L.D.V.) measurements were performed making possible a full estimation of the mean and turbulent 3D velocity fields in the mixing layer. The Reynolds stress tensor was described. In particular, some anisotropy coefficients were obtained. It appears that the structure of the Reynolds tensor is almost not affected by compressibility at least up to Mc = 1. The turbulent kinetic energy budget was also experimentally estimated. Reynolds analogies assumptions were used to obtain density/velocity correlations in order to build the turbulent kinetic energy budget from LDV measurements. Results have been compared to other experimental and numerical results. Compressibility effects on the turbulent kinetic energy budget have been detected and commented. A study about thermodynamics flow properties was also performed using most recent DNS results experimentally validated by the present data. A non-dimensional number is then introduced in order to quantify the real effect of pressure fluctuations on the thermodynamics quantities fluctuations

  1. Pulsed hydrogen fluoride laser oscillator-amplifier experiments

    International Nuclear Information System (INIS)

    Schott, G.L.

    1975-01-01

    Pulsed HF chemical laser oscillator energies were scaled from millijoules to several kilojoules over the period 1970-1974, reaching approximately 10 J with SF 6 and transverse discharges, and using electron-beam initiation and elemental F 2 above 1000J. This demonstrated scalability to large energy with acceptable electrical efficiency is only one prerequisite for application of this gas laser in fusion; equally important matters are achievement of focusable, approximately 1 ns pulses, couplable to light-element targets, all from an affordable system. Exploratory MOPA experiments are reported which address control of HF laser beam focusability and pulse duration, using SF 6 -based experimental oscillator--amplifier sequences and Pockels' cell switching. Simultaneous multiline lasing with 2.6 less than or equal to lambda less than or equal to 3.1 μm and high specific gain and energy density are particularly important factors encountered with HF, where amplifier pumping and lasing occur in a substantially cw temporal relationship, even in less than 100 ns bursts. Time-resolved SF 6 --HI oscillator spectra contain 27 simultaneous lines from six vibrational bands. An apertured, SF 6 -hydrocarbon pin-discharge oscillator generates approximately 10 mJ of TEM 00 radiation, which is amplified to approximately 1 J in approximately 150 ns by a TEA amplifier and p []opagated tens of meters. A three-stage system coupling these elements through an approximately 1 ns electrooptic gate to a greater than 10 J, e-beam energized amplifier is under development. (auth)

  2. Compact Ultraintense Femtosecond Laser via Raman Amplifier and Compressor in Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Suckewer, Szymon [Princeton Univ., NJ (United States)

    2016-03-01

    The main objective of this project was to conduct experimental and theoretical research to find conditions leading to higher, than previously obtained efficiency η of transfer the pump energy into the short seed beam in plasma of Stimulated Raman Back-Scattering (SRBS). We have demonstrated very large amplification and compression in our earlier SRBS plasma. However, the efficiency η was much too low to reach very high intensity of the output beam in the focal spot. Recently, by solving a very difficult technical SRBS’ problem, namely, the creation of very reproducible and much larger diameter plasma channels than in our earlier research, we propose a new approach to obtain higher efficiency η. The crucial new result was a very reproducible, low noise amplified seed in the larger diameter of the plasma channel leading to the higher efficiency. Using this new setup and very encouraging results about increase efficiency continuing this approach in the future the efficiency is expect to reach the range of η ≈15 - 20 % required to develop practical SRBS plasma laser. Intellectual Merit: The model for the present project was created by our earlier SRBS experiments. The main objective of those experiments was to amplify and compress the seed pulses in a plasma . The experiments demonstrated an unprecedented large pulse intensity amplification of 20,000 in system of 2-passes in ~2mm long plasma, and the seed pulse compression from 550fsec down to ~50fsec. The pump and seed beams in the present project have diameters of ~0.2–0.25mm each, propagating in ~0.35 - 0.45mm diameter and ~2-2.5mm long plasma channels (optimal length for our SRBS experiment) with input pump and seed intensities of 2x1014 and 3x1013 W/cm2, respectively. Such an SRBS system design was “prescribed” by computer simulations, which predict elimination of the SRBS “ saturation” for a such relatively short plasma channel. Plasma channels has been created by combining shorter (200psec) and

  3. Deep surface rolling for fatigue life enhancement of laser clad aircraft aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, W., E-mail: wyman.zhuang@dsto.defence.gov.au [Aerospace Division, Defence Science and Technology Organisation, 506 Lorimer Street, Fishermans Bend, Victoria 3207 (Australia); Liu, Q.; Djugum, R.; Sharp, P.K. [Aerospace Division, Defence Science and Technology Organisation, 506 Lorimer Street, Fishermans Bend, Victoria 3207 (Australia); Paradowska, A. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2232 (Australia)

    2014-11-30

    Highlights: • Deep surface rolling as a post-repair enhancement technology was applied to the laser cladded 7075-T651 aluminium alloy specimens that simulated corrosion damage blend-out repair. • The residual stresses induced by the deep surface rolling process were measured. • The deep surface rolling process can introduce deep and high magnitude compressive residual stresses beyond the laser clad and substrate interface. • Spectrum fatigue test showed the fatigue life was significantly increased by deep surface rolling. - Abstract: Deep surface rolling can introduce deep compressive residual stresses into the surface of aircraft metallic structure to extend its fatigue life. To develop cost-effective aircraft structural repair technologies such as laser cladding, deep surface rolling was considered as an advanced post-repair surface enhancement technology. In this study, aluminium alloy 7075-T651 specimens with a blend-out region were first repaired using laser cladding technology. The surface of the laser cladding region was then treated by deep surface rolling. Fatigue testing was subsequently conducted for the laser clad, deep surface rolled and post-heat treated laser clad specimens. It was found that deep surface rolling can significantly improve the fatigue life in comparison with the laser clad baseline repair. In addition, three dimensional residual stresses were measured using neutron diffraction techniques. The results demonstrate that beneficial compressive residual stresses induced by deep surface rolling can reach considerable depths (more than 1.0 mm) below the laser clad surface.

  4. Deep surface rolling for fatigue life enhancement of laser clad aircraft aluminium alloy

    International Nuclear Information System (INIS)

    Zhuang, W.; Liu, Q.; Djugum, R.; Sharp, P.K.; Paradowska, A.

    2014-01-01

    Highlights: • Deep surface rolling as a post-repair enhancement technology was applied to the laser cladded 7075-T651 aluminium alloy specimens that simulated corrosion damage blend-out repair. • The residual stresses induced by the deep surface rolling process were measured. • The deep surface rolling process can introduce deep and high magnitude compressive residual stresses beyond the laser clad and substrate interface. • Spectrum fatigue test showed the fatigue life was significantly increased by deep surface rolling. - Abstract: Deep surface rolling can introduce deep compressive residual stresses into the surface of aircraft metallic structure to extend its fatigue life. To develop cost-effective aircraft structural repair technologies such as laser cladding, deep surface rolling was considered as an advanced post-repair surface enhancement technology. In this study, aluminium alloy 7075-T651 specimens with a blend-out region were first repaired using laser cladding technology. The surface of the laser cladding region was then treated by deep surface rolling. Fatigue testing was subsequently conducted for the laser clad, deep surface rolled and post-heat treated laser clad specimens. It was found that deep surface rolling can significantly improve the fatigue life in comparison with the laser clad baseline repair. In addition, three dimensional residual stresses were measured using neutron diffraction techniques. The results demonstrate that beneficial compressive residual stresses induced by deep surface rolling can reach considerable depths (more than 1.0 mm) below the laser clad surface

  5. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    Kaita, R.; Heidbrink, W.W.; Hammett, G.W.

    1986-04-01

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and 3 He ions, respectively. When the plasma was compressed, the d(d,n) 3 He fusion reaction rate increased a factor of five, and the 3 He(d,p) 4 He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling

  6. Coulomb-Driven Relativistic Electron Beam Compression.

    Science.gov (United States)

    Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

    2018-01-26

    Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

  7. Coulomb-Driven Relativistic Electron Beam Compression

    Science.gov (United States)

    Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

    2018-01-01

    Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

  8. Theory and simulation of an inverse free-electron laser experiment

    Science.gov (United States)

    Gou, S. K.; Bhattacharjee, A.; Fang, J.-M.; Marshall, T. C.

    1997-03-01

    An experimental demonstration of the acceleration of electrons using a high-power CO2 laser interacting with a relativistic electron beam moving along a wiggler has been carried out at the Accelerator Test Facility of the Brookhaven National Laboratory [Phys. Rev. Lett. 77, 2690 (1996)]. The data generated by this inverse free-electron-laser (IFEL) experiment are studied by means of theory and simulation. Included in the simulations are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge; energy spread of the electrons; and arbitrary wiggler-field profile. Two types of wiggler profile are considered: a linear taper of the period, and a step-taper of the period. (The period of the wiggler is ˜3 cm, its magnetic field is ˜1 T, and the wiggler length is 0.47 m.) The energy increment of the electrons (˜1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (˜40 MeV). At a laser power level ˜0.5 Gw, the simulation results on energy gain are in reasonable agreement with the experimental results. Preliminary results on the electron energy distribution at the end of the IFEL are presented. Whereas the experiment produces a near-monotone distribution of electron energies with the peak shifted to higher energy, the simulation shows a more structured and non-monotonic distribution at the end of the wiggler. Effects that may help reconcile these differences are considered.

  9. Laser shock peening of Ti-17 titanium alloy: Influence of process parameters

    Energy Technology Data Exchange (ETDEWEB)

    Cellard, C.; Retraint, D.; Francois, M. [University of Technology of Troyes (UTT), Charles Delaunay Institute, LASMIS, UMR CNRS 6279, 12 Rue Marie Curie, BP2060, 10010 Troyes Cedex (France); Rouhaud, E., E-mail: rouhaud@utt.fr [University of Technology of Troyes (UTT), Charles Delaunay Institute, LASMIS, UMR CNRS 6279, 12 Rue Marie Curie, BP2060, 10010 Troyes Cedex (France); Le Saunier, D. [SNECMA Evry - Corbeil, Route Henry Auguste Desbrueres, 91003 Evry (France)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Laser shock peening parameters studied through a design of experiments. Black-Right-Pointing-Pointer Laser fluence, pulse duration, number of impacts and sample thickness are studied. Black-Right-Pointing-Pointer The observed work hardening is low, the roughness is lightly affected. Black-Right-Pointing-Pointer A significant part of hardness increase is due to compressive residual stresses. Black-Right-Pointing-Pointer High tensile residual stresses can appear on thin laser shocked specimens. - Abstract: The influence of the process parameters of laser shock peening was investigated on specimens made of an aeronautic titanium alloy: Ti-5Al-2Sn-2Zr-4Cr-4Mo (Ti-17). In order to quantify the effect of relevant process parameters, an experimental design was carried out. It is based on a full factorial design with four factors (laser fluence, pulse duration, number of impacts and thickness of the sample) and two levels for each factor. The process is characterised with the following variables: the depth of the impacts, the roughness of the treated surface, the hardening of the material (itself evaluated with the hardness and X-ray diffraction peak width), the residual stresses left in the sample and the global curvature of the sample. It is found that all the parameters have an influence on the residual stresses and that laser shock peening has no influence on roughness and low influence on work-hardening. The variables are then analysed in order to evaluate correlations. The increase in hardness is found to be essentially due to compressive residual stresses, cold work-hardening having only a small effect. In thin specimens, the stress redistribution due to self-equilibrium leads to tensile residual stresses at the treated surface and to large deformations of the specimens.

  10. Relativistic self focussing of laser beams at fast ignitor inertial fusion with volume ignition

    International Nuclear Information System (INIS)

    Osman, F.; Castillo, R.; Hora, H.

    1999-01-01

    The alternative to the magnetic confinement fusion is inertial fusion energy mostly using lasers as drivers for compression and heating of pellets with deuterium and tritium fuel. Following the present technology of lasers with pulses of some megajoules energy and nanosecond duration, a power station for very low cost energy production (and without the problems of well erosion of magnetic confinement) could be available within 15 to 20 years. For the pellet compression, the scheme of spark ignition was mostly applied but its numerous problems with asymmetries and instabilities may be overcome by the alternative scheme of high gain volume ignition. This is a well established option of inertial fusion energy with lasers where a large range of possible later improvements is implied with respect to laser technology or higher plasma compression leading to energy production of perhaps five times below the present lowest level cost from fission reactors. A further improvement may be possible by the recent development of lasers with picosecond pulse duration using the fast igniter scheme which may reach even higher fusion gains with laser pulse energies of some 100 kilojoules

  11. P. W. Bridgman's contributions to the foundations of shock compression of condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Nellis, W J, E-mail: nellis@physics.harvard.ed [Department of Physics, Harvard University, Cambridge MA 02138 (United States)

    2010-03-01

    Based on his 50-year career in static high-pressure research, P. W. Bridgman (PWB) is the father of modern high-pressure physics. What is not generally recognized is that Bridgman was also intimately connected with establishing shock compression as a scientific tool and he predicted major events in shock research that occurred up to 40 years after his death. In 1956 the first phase transition under shock compression was reported in Fe at 13 GPa (130 kbar). PWB said a phase transition could not occur in a {approx}microsec, thus setting off a controversy. The scientific legitimacy of shock compression resulted 5 years later when static high-pressure researchers confirmed with x-ray diffraction the existence of epsilon-Fe. Once PWB accepted the fact that shock waves generated with chemical explosives were a valid scientific tool, he immediately realized that substantially higher pressures would be achieved with nuclear explosives. He included his ideas for achieving higher pressures in articles published a few years after his death. L. V. Altshuler eventually read Bridgman's articles and pursued the idea of using nuclear explosives to generate super high pressures, which subsequently morphed today into giant lasers. PWB also anticipated combining static and shock methods, which today is done with pre-compression of a soft sample in a diamond anvil cell followed by laser-driven shock compression. One variation of that method is the reverberating-shock technique, in which the first shock pre-compresses a soft sample and subsequent reverberations isentropically compress the first-shocked state.

  12. A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

    Science.gov (United States)

    Klipstein, W. M.; Kohel, J.; Seidel, D. J.; Thompson, R. J.; Maleki, L.; Gibble, K.

    2000-01-01

    We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

  13. Significant skin-tightening by closure of fractional ablative laser holes.

    Science.gov (United States)

    Russe, Elisabeth; Purschke, Martin; Limpiangkanan, Wikunda; Farinelli, William A; Wang, Ying; Doukas, Apostolos G; Sakamoto, Fernanda H; Wechselberger, Gottfried; Anderson, Richard Rox

    2018-01-01

    Ablative fractional laser treatment uses thousands of very small laser beam wounds to damage a fraction of the skin, which stimulates tissue remodeling. Each open micro-wound heals without scarring, but the amount of skin tightening achieved is limited. This animal study was performed to test the hypothesis that immediate temporary closure of fractional laser wounds could increase skin tightening after fractional ablative laser treatment. Four adult swine were used for the study; 98 square test sites (3 × 3 cm) were tattooed on the abdomen and flanks of each pig. An ablative fractional Erbium:YAG laser (Sciton Profile, Sciton Inc, Palo Alto, CA) was used to treat the test areas. A laser micro-spot fluence of 375 J/cm 2 was delivered in 150-250 microseconds pulses, resulting in an array of ablation channels extending 1.5 mm deep into the skin, with a spot size of 250 µm, with 10% treatment density. Immediately following laser exposure the resulting holes were closed using a stretched elastic adhesive dressing, which, when applied, recoiled and compressed the diameter of the ablation holes. The compressive dressings were removed after 7 days. This procedure was compared to removing the same amount of skin (10%) mechanically by specially designed 19 gauge coring needles, as well as to the same laser and coring methods without compression closure. Area and shape of test sites were measured by digital photography before and 28 days after treatment. Data analysis included compensation for animal growth, as measured by increase in the area of the untreated control sites. All treated and control sites healed within a week, without scarring evident at 28 days. Laser treatment combined with compressive wound closure caused significant shrinkage at 28 days compared with untreated control sites. The treated skin area was reduced by 11.5% (P = 0.0001). Needle coring with wound closure produced similar, significant shrinkage (8%, P < 0.0021), whereas laser

  14. Experiments on laser driven beatwave acceleration in a ponderomotively formed plasma channel

    International Nuclear Information System (INIS)

    Tochitsky, S.Ya.; Narang, R.; Filip, C.V.; Clayton, C.E.; Marsh, K.A.; Joshi, C.; Musumeci, P.; Yoder, R.B.; Rosenzweig, J.B.; Pellegrini, C.

    2004-01-01

    A 10 ps long beam of 12 MeV electrons is externally injected into a ∼3-cm long plasma beatwave excited in a laser ionized hydrogen gas. The electrons have been accelerated to 50 MeV with a gradient of ∼1.3 GeV/m. It is shown that when the effective plasma wave amplitude-length product is limited by ionization-induced defocusing (IID), acceleration of electrons is significantly enhanced by using a laser pulse with a duration longer than the time required for ions to move across the laser spot size. Both experiments and two-dimensional simulations reveal that, in this case, self-guiding of the laser pulse in a ponderomotively formed plasma channel occurs. This compensates for IID and drives the beatwave over the longer length compared to when such a channel is not present

  15. Experimental and Numerical Study of Jet Controlled Compression Ignition on Combustion Phasing Control in Diesel Premixed Compression Ignition Systems

    OpenAIRE

    Qiang Zhang; Wuqiang Long; Jiangping Tian; Yicong Wang; Xiangyu Meng

    2014-01-01

    In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI) for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics were analyzed based on the BMEP of 2.18 bar. The simulation results showed that the high temperature j...

  16. Bombyx mori silk protein films microprocessing with a nanosecond ultraviolet laser and a femtosecond laser workstation: theory and experiments

    Science.gov (United States)

    Lazare, S.; Sionkowska, A.; Zaborowicz, M.; Planecka, A.; Lopez, J.; Dijoux, M.; Louména, C.; Hernandez, M.-C.

    2012-01-01

    Laser microprocessing of several biopolymers from renewable resources is studied. Three proteinic materials were either extracted from the extracellular matrix like Silk Fibroin/Sericin and collagen, or coming from a commercial source like gelatin. All can find future applications in biomedical experimentation, in particular for cell scaffolding. Films of ˜hundred of microns thick were made by aqueous solution drying and laser irradiation. Attention is paid to the properties making them processable with two laser sources: the ultraviolet and nanosecond (ns) KrF (248 nm) excimer and the infrared and femtosecond (fs) Yb:KGW laser. The UV radiation is absorbed in a one-photon resonant process to yield ablation and the surface foaming characteristics of a laser-induced pressure wave. To the contrary, resonant absorption of the IR photons of the fs laser is not possible and does not take place. However, the high field of the intense I>˜1012 W/cm2 femtosecond laser pulse ionizes the film by the multiphoton absorption followed by the electron impact mechanism, yielding a dense plasma capable to further absorb the incident radiation of the end of the pulse. The theoretical model of this absorption is described in detail, and used to discuss the presented experimental effects (cutting, ablation and foaming) of the fs laser. The ultraviolet laser was used to perform simultaneous multiple spots experiments in which energetic foaming yields melt ejection and filament spinning. Airborne nanosize filaments "horizontally suspended by both ends" (0.25 μm diameter and 10 μm length) of silk biopolymer were observed upon irradiation with large fluences.

  17. Volume ignition of laser driven fusion pellets and double layer effects

    International Nuclear Information System (INIS)

    Cicchitelli, L.; Eliezer, S.; Goldsworthy, M.P.; Green, F.; Hora, H.; Ray, P.S.; Stening, R.J.; Szichman, H.

    1988-01-01

    The realization of an ideal volume compression of laser-irradiated fusion pellets opens the possibility for an alternative to spark ignition proposed for many years for inertial confinement fusion. A re-evaluation of the difficulties of the central spark ignition of laser driven pellets is given. The alternative volume compression theory, together with volume burn and volume ignition, have received less attention and are re-evaluated in view of the experimental verification generalized fusion gain formulas, and the variation of optimum temperatures derived at self-ignition. Reactor-level DT fusion with MJ-laser pulses and volume compression to 50 times the solid-state density are estimated. Dynamic electric fields and double layers at the surface and in the interior of plasmas result in new phenomena for the acceleration of thermal electrons to suprathermal electrons. Double layers also cause a surface tension which stabilizes against surface wave effects and Rayleigh-Taylor instabilities. (author)

  18. Compressed normalized block difference for object tracking

    Science.gov (United States)

    Gao, Yun; Zhang, Dengzhuo; Cai, Donglan; Zhou, Hao; Lan, Ge

    2018-04-01

    Feature extraction is very important for robust and real-time tracking. Compressive sensing provided a technical support for real-time feature extraction. However, all existing compressive tracking were based on compressed Haar-like feature, and how to compress many more excellent high-dimensional features is worth researching. In this paper, a novel compressed normalized block difference feature (CNBD) was proposed. For resisting noise effectively in a highdimensional normalized pixel difference feature (NPD), a normalized block difference feature extends two pixels in the original formula of NPD to two blocks. A CNBD feature can be obtained by compressing a normalized block difference feature based on compressive sensing theory, with the sparse random Gaussian matrix as the measurement matrix. The comparative experiments of 7 trackers on 20 challenging sequences showed that the tracker based on CNBD feature can perform better than other trackers, especially than FCT tracker based on compressed Haar-like feature, in terms of AUC, SR and Precision.

  19. Temporal compression in episodic memory for real-life events.

    Science.gov (United States)

    Jeunehomme, Olivier; Folville, Adrien; Stawarczyk, David; Van der Linden, Martial; D'Argembeau, Arnaud

    2018-07-01

    Remembering an event typically takes less time than experiencing it, suggesting that episodic memory represents past experience in a temporally compressed way. Little is known, however, about how the continuous flow of real-life events is summarised in memory. Here we investigated the nature and determinants of temporal compression by directly comparing memory contents with the objective timing of events as measured by a wearable camera. We found that episodic memories consist of a succession of moments of prior experience that represent events with varying compression rates, such that the density of retrieved information is modulated by goal processing and perceptual changes. Furthermore, the results showed that temporal compression rates remain relatively stable over one week and increase after a one-month delay, particularly for goal-related events. These data shed new light on temporal compression in episodic memory and suggest that compression rates are adaptively modulated to maintain current goal-relevant information.

  20. Convective mechanism for inhibition of heat conduction in laser produced plasmas

    International Nuclear Information System (INIS)

    Lee, P.H.Y.; Willi, O.; Trainor, R.J.

    1984-01-01

    In laser-produced plasmas, the laser energy is absorbed only below and up to the critical density. For laser fusion applications, this energy must be transported beyond the corona via electron thermal conduction towards colder, higher density regions of the target to heat up material and cause ablation, which in turn generates an inward pressure to compress the fusion fuel. If the heat conduction is inhibited, the consequences will be a weaker ablation and therefore a weaker implosion. For many years now, the inhibition of heat conduction, i.e., the reduction of heat conduction relative to classical conduction, in laser-produced plasmas at relevant irradiances has been apparent from the large body of experimental evidence. Many mechanisms, such as dc magnetic fields, ion acoustic turbulence, and Weibel instabilities, have been proposed to be the cause of inhibition of heat conduction. Even improved calculations of the classical heat flux have been carried out to solve this problem. Nevertheless, no single one of the above mentioned mechanisms can explain the large inhibition observed in the experiments

  1. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  2. Thermal Effects on Thin Laser-Peened Ferritic-Martensitic Samples

    International Nuclear Information System (INIS)

    Caro, M; Zalesky, T; Hosemann, P; El-dasher, B S; Halsey, W G; Stuart, B

    2007-01-01

    Laser peening is emerging as a promising technique to improve the corrosion resistance of cladding material candidates for lead-cooled fast reactors (LFRs). The challenge is in the performance capability of ∼1 mm-thick fuel-pin cladding. Ferritic-martensitic (F/M) steels are foreseen as possible candidates that stand severe conditions of high dose (150 dpa), and high temperature (∼500-600 C) under the corrosive environments of molten lead or lead-bismuth. In this paper, we present the results of experiments carried on laser peened (LP) samples of F/M steels HT9, T91, EP823, as well as the austenitic material 316 L. The samples underwent a thermal treatment in an oven at 520 C, and XRD compressive stress results indicate that the F/M samples do not retain the residual stress after 2 weeks of heat treatment. The corrosion behavior in flowing lead-bismuth eutectic (LBE) at 535 C has been investigated as well. Also, irradiation experiments of LP samples to a maximum dose of ∼10 dpa are foreseen

  3. The LILIA (laser induced light ions acceleration) experiment at LNF

    International Nuclear Information System (INIS)

    Agosteo, S.; Anania, M.P.; Caresana, M.; Cirrone, G.A.P.; De Martinis, C.; Delle Side, D.; Fazzi, A.; Gatti, G.; Giove, D.; Giulietti, D.; Gizzi, L.A.; Labate, L.; Londrillo, P.; Maggiore, M.; Nassisi, V.; Sinigardi, S.; Tramontana, A.; Schillaci, F.; Scuderi, V.; Turchetti, G.

    2014-01-01

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given

  4. The LILIA (laser induced light ions acceleration) experiment at LNF

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Anania, M.P. [INFN LNF Frascati, Frascati (Italy); Caresana, M. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Cirrone, G.A.P. [INFN LNS Catania, Catania (Italy); De Martinis, C. [Physics Department, University of Milan and INFN, Milan (Italy); Delle Side, D. [LEAS, University of Salento and INFN, Lecce (Italy); Fazzi, A. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Gatti, G. [INFN LNF Frascati, Frascati (Italy); Giove, D. [Physics Department, University of Milan and INFN, Milan (Italy); Giulietti, D. [Physics Department, University of Pisa and INFN, Pisa (Italy); Gizzi, L.A.; Labate, L. [INO-CNR and INFN, Pisa (Italy); Londrillo, P. [Physics Department, University of Bologna and INFN, Bologna (Italy); Maggiore, M. [INFN LNL, Legnaro (Italy); Nassisi, V., E-mail: vincenzo.nassisi@le.infn.it [LEAS, University of Salento and INFN, Lecce (Italy); Sinigardi, S. [Physics Department, University of Bologna and INFN, Bologna (Italy); Tramontana, A.; Schillaci, F. [INFN LNS Catania, Catania (Italy); Scuderi, V. [INFN LNS Catania, Catania (Italy); Institute of Physics of the ASCR, Prague (Czech Republic); Turchetti, G. [Physics Department, University of Bologna and INFN, Bologna (Italy); and others

    2014-07-15

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  5. Advances for laser ignition of internal combustion and rocket engines

    International Nuclear Information System (INIS)

    Schwarz, E.

    2011-01-01

    field laser physics. Unfortunately, there is no standard definition for the plasma threshold in the literature. Consequently, a clear definition of the focal volume is missing. For this reason it was tried to find a theoretical formula for the volume. This formula is based on the assumption that the focal volume encloses the space where the threshold intensity is higher than Ith =I0/2 or, alternatively, Ith = I0/e2. Laser energy transmission is one of the most important loss factors during plasma development by laser-induced optical breakdown and provides important information about the energy contained in the plasma. Hence, a number of plasma experiments were carried out. In our experiments is was found that for decreasing focal volume the plasma threshold energy (MPE) and the energy transmission can be reduced respectively. In order to investigate the possibility if laser-induced ignition can be made more efficient with respect to the laser pulse energy, several ignition experiments were performed. For these experiments a combustion chamber was employed at a filling pressure of 11 bar and a temperature of 110 o C involving different focal sizes. The thermal ignition experiments were carried out to demonstrate in principle the feasibility of thermal ignition via resonant absorption of IR radiation. By evaluating these results with respect to laser ignition of engines, it is conceivable to employ laser thermal ignition as an innovative ignition mechanism. As in HCCI (homogeneous charge compression ignition) engines and rocket engines, ignition occurs at specific elevated pressures and temperatures, it can be assumed that the ignition energies are in the range between 20 to 100 mJ. Furthermore, different laser ignition system concepts were developed and evaluated regarding to their qualification for rocket engine ignition. As a consequence of its highest rating in our study, resonant ignition should be considered an interesting alternative to laser spark ignition

  6. Magnetic compression/magnetized target fusion (MAGO/MTF)

    International Nuclear Information System (INIS)

    Kirkpatrick, R.C.; Lindemuth, I.R.

    1997-03-01

    Magnetized Target Fusion (MTF) was reported in two papers at the First Symposium on Current Trends in International Fusion Research. MTF is intermediate between two very different mainline approaches to fusion: Inertial Confinement Fusion (ICF) and magnetic confinement fusion (MCF). The only US MTF experiments in which a target plasma was compressed were the Sandia National Laboratory ''Phi targets''. Despite the very interesting results from that series of experiments, the research was not pursued, and other embodiments of MTF concept such as the Fast Liner were unable to attract the financial support needed for a firm proof of principle. A mapping of the parameter space for MTF showed the significant features of this approach. The All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) has an on-going interest in this approach to thermonuclear fusion, and Los Alamos National Laboratory (LANL) and VNIIEF have done joint target plasma generation experiments relevant to MTF referred to as MAGO (transliteration of the Russian acronym for magnetic compression). The MAGO II experiment appears to have achieved on the order of 200 eV and over 100 KG, so that adiabatic compression with a relatively small convergence could bring the plasma to fusion temperatures. In addition, there are other experiments being pursued for target plasma generation and proof of principle. This paper summarizes the previous reports on MTF and MAGO and presents the progress that has been made over the past three years in creating a target plasma that is suitable for compression to provide a scientific proof of principle experiment for MAGO/MTF

  7. Residual stress improvement mechanism on metal material by underwater laser irradiation

    International Nuclear Information System (INIS)

    Sano, Yuji; Yoda, Masaki; Mukai, Naruhiko; Obata, Minoru; Kanno, Masanori

    2000-01-01

    Residual stress improvement technology for component surface by underwater pulsed laser irradiation has been developed as a method of preventing stress corrosion cracking (SCC) of core components in nuclear reactors. In order to optimize the laser irradiation conditions based on a complete understanding of the mechanism, the propagation of a shock wave induced by the impulse of laser irradiation and the dynamic response of the irradiated material were analyzed through time-dependent elasto-plastic calculations with a finite element program. The calculated results are compared with the measured results obtained by experiments in which laser pulses with an energy of 200 mJ are focused to a diameter of 0.8 mm on a water-immersed test piece of 20% cold-worked Type 304 austenitic stainless steel to simulate neutron irradiation hardening. A residual compressive stress, which is nearly equivalent to the yield stress of the processed material, remains on the material surface after passage of the shock wave with enough amplitude to induce a permanent strain. Multiple irradiation of laser pulses extends the stress-improved depth to about 1 mm, which would be the limit corresponding to the three-dimensional dispersion effect of the shock wave. (author)

  8. Increae of thermonuclear field on fast implosion of cold shell targets by means on nonlinear interaction of laser radiation with plasma

    International Nuclear Information System (INIS)

    Khora, Kh.

    1976-01-01

    The nonlinear interaction force between laser fields and cold plasma shells efficiently transforms radiant energy into mechanical energy of implosion. This transfer of energy has been considered before in numerical experiments and is treated here analytically in a didactic example starting with the inhomogeneous Rayleigh density profile. Up to 50% of the laser energy can be transferred into the energy of compression is a single, untailored pulse of 2.5x10 16 W/cm 2 intensity and of only a few picoseconds duration is used for spherical illumination of the shell. If the pulse is short enough to reduce collisional thermalization, then the collapse and compression of the plasma can remain both at the threshold of Fermi degeneracy and adiabatic. This results in nuclear reaction gains G, based on the deposited energy, E 0 , and without a-particle reheating, of G=400 for E 0 =2.25 kJ (DT), 900 kJ(DD), 13MJ (HB). About 1000 times less laser energy is necessary than in the case of gas dynamic ablation resulting in the same nuclear reaction yields

  9. Study of CSR longitudinal bunch compression cavity

    International Nuclear Information System (INIS)

    Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

    2009-01-01

    The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

  10. Integrated laser-target interaction experiments on the RAL petawatt laser

    International Nuclear Information System (INIS)

    Patel, P K; Key, M H; Mackinnon, A J

    2005-01-01

    We review a recent experimental campaign to study the interaction physics of petawatt laser pulses incident at relativistic intensities on solid targets. The campaign was performed on the 500 J sub-picosecond petawatt laser at the Rutherford Appleton Laboratory. An extensive suite of optical, x-ray, and particle diagnostics was employed to characterise the processes of laser absorption, electron generation and transport, thermal and K-alpha x-ray generation, and proton acceleration

  11. Phase Transitions in Aluminum Under Shockless Compression at the Z Machine

    Science.gov (United States)

    Davis, Jean-Paul; Brown, Justin; Shulenburger, Luke; Knudson, Marcus

    2017-06-01

    Aluminum 6061 alloy has been used extensively as an electrode material in shockless ramp-wave experiments at the Z Machine. Previous theoretical work suggests that the principal quasi-isentrope in aluminum should pass through two phase transitions at multi-megabar pressures, first from the ambient fcc phase to hcp at around 200 GPa, then to bcc at around 320 GPa. Previous static measurements in a diamond-anvil cell have detected the hcp phase above 200 GPa along the room-temperature isentherm. Recent laser-based dynamic compression experiments have observed both the hcp and bcc phases using X-ray diffraction. Here we present high-accuracy velocity waveform data taken on pure and alloy aluminum materials at the Z Machine under shockless compression with 200-ns rise-time to 400 GPa using copper electrodes and lithium-fluoride windows. These are compared to recent EOS tables developed at Los Alamos National Laboratory, to our own results from diffusion quantum Monte-Carlo calculations, and to multi-phase EOS models with phase-transition kinetics. We find clear evidence of a fast transition around 200 GPa as expected, and a possible suggestion of a slower transition at higher pressure. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE AC04-94AL85000.

  12. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development.

    Energy Technology Data Exchange (ETDEWEB)

    Kearney, Sean Patrick; Jilek, Brook Anton; Kohl, Ian Thomas; Farrow, Darcie; Urayama, Junji

    2014-11-01

    We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties during shock compression of condensed phase materials at micron spatial scales and picosecond time scales. The report is structured into three main chapters, which each focus on a different diagnostic devel opment effort. Direct picosecond laser drive is used to introduce shock waves into thin films of energetic and inert materials. The resulting laser - driven shock properties are probed via Ultrafast Time Domain Interferometry (UTDI), which can additionally be used to generate shock Hugoniot data in tabletop experiments. Stimulated Raman scattering (SRS) is developed as a temperature diagnostic. A transient absorption spectroscopy setup has been developed to probe shock - induced changes during shock compressio n. UTDI results are presented under dynamic, direct - laser - drive conditions and shock Hugoniots are estimated for inert polystyrene samples and for the explosive hexanitroazobenzene, with results from both Sandia and Lawrence Livermore presented here. SRS a nd transient absorption diagnostics are demonstrated on static thin - film samples, and paths forward to dynamic experiments are presented.

  13. Sustainability of compressive residual stress by stress improvement processes

    International Nuclear Information System (INIS)

    Nishikawa, Satoru; Okita, Shigeru; Yamaguchi, Atsunori

    2013-01-01

    Stress improvement processes are countermeasures against stress corrosion cracking in nuclear power plant components. It is necessary to confirm whether compressive residual stress induced by stress improvement processes can be sustained under operation environment. In order to evaluate stability of the compressive residual stress in 60-year operating conditions, the 0.07% cyclic strains of 200 times at 593 K were applied to the welded specimens, then a thermal aging treatment for 1.66x10 6 s at 673 K was carried out. As the result, it was confirmed that the compressive residual stresses were sustained on both surfaces of the dissimilar welds of austenitic stainless steel (SUS316L) and nickel base alloy (NCF600 and alloy 182) processed by laser peening (LP), water jet peening (WJP), ultrasonic shot peening (USP), shot peening (SP) and polishing under 60-year operating conditions. (author)

  14. Assiut Experience in the Application of Holmium Laser in Treatment ...

    African Journals Online (AJOL)

    Assiut Experience in the Application of Holmium Laser in Treatment of Ureteral Calculi in Adults. A.M. Abdel Lateef, A.E. Abdel Moniem, M.I. Taha, M.A. Shalaby. Abstract. Internal Optical Urethrotomy at the National Medical Center of Sanou Souro in Bobo-Dioulasso: Feasibility, Safety and Short-Term Results Objective To ...

  15. Ultraporous, Compressible, Wettable Polylactide/Polycaprolactone Sponges for Tissue Engineering.

    Science.gov (United States)

    Mader, Michael; Jérôme, Valérie; Freitag, Ruth; Agarwal, Seema; Greiner, Andreas

    2018-05-14

    Ultraporous, degradable sponges made of either polylactide or of blends of polylactide/poly(ε-caprolactone) are prepared by freeze-drying of dispersions of short electrospun fibers and subsequent thermal annealing. The sponges feature ultrahigh porosity (99.6%), a hierarchical cellular structure, and high reversible compressibility with fast recovery from deformation in the dry as well as in the wet state. The sponge properties depend on the fiber dispersion concentration and the annealing temperature. Sponge characteristics like fiber density (2.5-20 mg/cm 3 ), size, shape, crystallinity, mechanical strength, wetability, and structural integrity are user adjustable. Cell culture experiments were successfully performed with Jurkat cells with Confocal Laser Scanning Microscopy and MTT staining showing rapid cell proliferation. Live/Dead staining demonstrated high viability of the seeded cells. The sponge characteristics and modifications investigated and presented here reveal that these sponges are highly promising for tissue engineering applications.

  16. X-ray flux and X-ray burn through experiments on reduced-scale targets at the Nif and OMEGA lasers

    International Nuclear Information System (INIS)

    Schneider, M.B.; Hinkel, D.E.; Young, B.K.; Holder, J.P.; Langdon, A.B.; Bower, D.E.; Bruns, H.C.; Campbell, K.M.; Celeste, J.R.; Compton, S.; Costa, R.L.; Dewald, E.L.; Dixit, S.N.; Eckart, M.J.; Eder, D.C.; Edwards, M.J.; Ellis, A.D.; Emig, J.A.; Froula, D.H.; Glebov, V.; Glenzer, S.H.; Hargrove, D.; Haynam, C.A.; Heeter, R.F.; Henesian, M.A.; Holtmeier, G.; James, D.L.; Jancaitis, K.S.; Kalantar, D.H.; Kamperschroer, J.H.; Kauffman, R.L.; Kimbrough, J.; Kirkwood, R.; Koniges, A.E.; Landen, O.L.; Landon, M.; Lee, F.D.; MacGowan, B.J.; Mackinnon, A.J.; Manes, K.R.; Marshall, C.; May, M.J.; McDonald, J.W.; Menapace, J.; Moon, S.J.; Moses, E.I.; Munro, D.H.; Murray, J.R.; Niemann, C.; Piston, K.; Power, G.D.; Rekow, V.; Ruppe, J.A.; Schein, J.; Shepherd, R.; Singh, M.S.; Sorce, C.; Springer, P.T.; Still, C.H.; Suter, L.J.; Tietbohl, G.L.; Turner, R.E.; Van Wonterghem, B.M.; Wallace, R.J.; Warrick, A.; Weber, F.; Wegner, P.J.; Williams, E.A.; Young, P.E.; Baldis, H.A.; Constantin, C.G.; Bahr, R.; Roberts, S.; Seka, W.; Stoeckl, C.; Pellinen, D.; Watts, P.

    2006-01-01

    An experimental campaign to maximize radiation drive in small-scale hohlraums has been carried out at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (Livermore, USA) and at the OMEGA laser at the Laboratory for Laser Energetics (Rochester, USA). The small-scale hohlraums, laser energy, laser pulse, and diagnostics were similar at both facilities but the geometries were very different. The NIF experiments used on-axis laser beams whereas the OMEGA experiments used 19 beams in three beam cones. In the cases when the lasers coupled well and produced similar radiation drive, images of X-ray burn-through and laser deposition indicate the pattern of plasma filling is very different. The OMEGA targets fill faster than the NIF targets, which helps explain the time behavior of the X-ray fluences. (authors)

  17. X-ray flux and X-ray burn through experiments on reduced-scale targets at the Nif and OMEGA lasers

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.B.; Hinkel, D.E.; Young, B.K.; Holder, J.P.; Langdon, A.B.; Bower, D.E.; Bruns, H.C.; Campbell, K.M.; Celeste, J.R.; Compton, S.; Costa, R.L.; Dewald, E.L.; Dixit, S.N.; Eckart, M.J.; Eder, D.C.; Edwards, M.J.; Ellis, A.D.; Emig, J.A.; Froula, D.H.; Glebov, V.; Glenzer, S.H.; Hargrove, D.; Haynam, C.A.; Heeter, R.F.; Henesian, M.A.; Holtmeier, G.; James, D.L.; Jancaitis, K.S.; Kalantar, D.H.; Kamperschroer, J.H.; Kauffman, R.L.; Kimbrough, J.; Kirkwood, R.; Koniges, A.E.; Landen, O.L.; Landon, M.; Lee, F.D.; MacGowan, B.J.; Mackinnon, A.J.; Manes, K.R.; Marshall, C.; May, M.J.; McDonald, J.W.; Menapace, J.; Moon, S.J.; Moses, E.I.; Munro, D.H.; Murray, J.R.; Niemann, C.; Piston, K.; Power, G.D.; Rekow, V.; Ruppe, J.A.; Schein, J.; Shepherd, R.; Singh, M.S.; Sorce, C.; Springer, P.T.; Still, C.H.; Suter, L.J.; Tietbohl, G.L.; Turner, R.E.; Van Wonterghem, B.M.; Wallace, R.J.; Warrick, A.; Weber, F.; Wegner, P.J.; Williams, E.A.; Young, P.E. [Lawrence Livermore National Lab., Livermore, CA (United States); Baldis, H.A.; Constantin, C.G. [California at Davis Univ., CA (United States); Bahr, R.; Roberts, S.; Seka, W.; Stoeckl, C. [Laboratory for Laser Energetics, Rochester, NY (United States); Pellinen, D.; Watts, P. [Bechtel Nevada Corporation, Livermore, CA (United States)

    2006-06-15

    An experimental campaign to maximize radiation drive in small-scale hohlraums has been carried out at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (Livermore, USA) and at the OMEGA laser at the Laboratory for Laser Energetics (Rochester, USA). The small-scale hohlraums, laser energy, laser pulse, and diagnostics were similar at both facilities but the geometries were very different. The NIF experiments used on-axis laser beams whereas the OMEGA experiments used 19 beams in three beam cones. In the cases when the lasers coupled well and produced similar radiation drive, images of X-ray burn-through and laser deposition indicate the pattern of plasma filling is very different. The OMEGA targets fill faster than the NIF targets, which helps explain the time behavior of the X-ray fluences. (authors)

  18. Laser fusion and future energy sources - some recent results

    International Nuclear Information System (INIS)

    Hora, H.

    1979-01-01

    While the laser fusion is at present producing more genuine fusion neutrons than the tokamak with magnetic confinement, if use of short laser pulses is preferred, the then appearing nonlinear effect causes considerable complications. Nonlinear processes for the preferred geometry of perpendicular incidence can avoid the problems of resonance absorption, while parametric instabilities have no quantitative influence on the energy balance. The early stages of interaction show the generation of thick 'cold' compressing plasma blocks which can be used for a nonlinear force fast pusher compression of high efficiency (low entropy production). A short time interaction results in a fast thermalization of the plasma corona by soliton decay and this provides the necessary condition for Nuckolls' gasdynamic ablation compression. For longer duration of high intensity irradiation, a pulsation of reflectivity and thermalization will complicate the interaction

  19. A description of the apparatus to be used in interaction experiments with the ABC laser system

    International Nuclear Information System (INIS)

    Caruso, A.; Strangio, M.; Andreoli, P.L.; Cerioni, I.; Di Paolo, A.; Di Virgilio, L.

    1988-01-01

    This report contains the part of the Frascati Laboratorio Fusione Laser activity related to the Apparatus (target chamber, position and alignement system, diagnostics) to be used in the interaction experiments with the ABC laser system

  20. Commissioning experience and beam physics measurements at the SwissFEL Injector test Facility

    CERN Document Server

    Schietinger, T.; Aiba, M.; Arsov, V.; Bettoni, S.; Beutner, B.; Calvi, M.; Craievich, P.; Dehler, M.; Frei, F.; Ganter, R.; Hauri, C. P.; Ischebeck, R.; Ivanisenko, Y.; Janousch, M.; Kaiser, M.; Keil, B.; Löhl, F.; Orlandi, G. L.; Ozkan Loch, C.; Peier, P.; Prat, E.; Raguin, J.-Y.; Reiche, S.; Schilcher, T.; Wiegand, P.; Zimoch, E.; Anicic, D.; Armstrong, D.; Baldinger, M.; Baldinger, R.; Bertrand, A.; Bitterli, K.; Bopp, M.; Brands, H.; Braun, H. H.; Brönnimann, M.; Brunnenkant, I.; Chevtsov, P.; Chrin, J.; Citterio, A.; Csatari Divall, M.; Dach, M.; Dax, A.; Ditter, R.; Divall, E.; Falone, A.; Fitze, H.; Geiselhart, C.; Guetg, M. W.; Hämmerli, F.; Hauff, A.; Heiniger, M.; Higgs, C.; Hugentobler, W.; Hunziker, S.; Janser, G.; Kalantari, B.; Kalt, R.; Kim, Y.; Koprek, W.; Korhonen, T.; Krempaska, R.; Laznovsky, M.; Lehner, S.; Le Pimpec, F.; Lippuner, T.; Lutz, H.; Mair, S.; Marcellini, F.; Marinkovic, G.; Menzel, R.; Milas, N.; Pal, T.; Pollet, P.; Portmann, W.; Rezaeizadeh, A.; Ritt, S.; Rohrer, M.; Schär, M.; Schebacher, L.; Scherrer, St.; Schlott, V.; Schmidt, T.; Schulz, L.; Smit, B.; Stadler, M.; Steffen, Bernd; Stingelin, L.; Sturzenegger, W.; Treyer, D. M.; Trisorio, A.; Tron, W.; Vicario, C.; Zennaro, R.; Zimoch, D.

    2016-10-26

    The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and test bed for the development and realization of SwissFEL, the x-ray Free Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including atransverse deflecting rf cavity. It delivered electron bunchesof up to200 pC chargeand up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of a FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultralow-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measureme...

  1. Surface contamination of the LIL optical components and their evolution after laser irradiation (1. series of experiments); La pollution surfacique de la LIL et son evolution sur un composant optique soumis a une irradiation laser (1. serie d'experiences)

    Energy Technology Data Exchange (ETDEWEB)

    Palmier, St.; Garcia, S.; Lamaignere, L.; Manac' h, P.; Rullier, J.L.; Tovena, I

    2006-07-01

    In the context of the Laser Megajoule project, a study has been carried out to observe the correlation between particle contamination at the surface of the optical components and laser irradiation. The experiments consist in placing silica samples in the Ligne d'Integration Laser (LIL) environment more precisely around the frequency conversion crystals and beam focusing area. Particle contamination at the surface samples is characterized and quantified. Then its behaviour under 1064 nm laser irradiation is observed. From the results of this first series of experiments, it appears that on irradiated silica samples treated with anti reflection coatings, surface particles or contamination can induce a surface defect. (author)

  2. High-Mach number, laser-driven magnetized collisionless shocks

    International Nuclear Information System (INIS)

    Schaeffer, Derek B.; Fox, W.; Haberberger, D.; Fiksel, G.; Bhattacharjee, A.

    2017-01-01

    Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and magnetized ambient plasma. Through time-resolved, 2-D imaging we observe large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. Electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. Furthermore, the simulations also show the shock separating from the piston, which we observe in the data at late experimental times.

  3. Volume Measurements of Laser-generated Pits for In Situ Geochronology using KArLE (Potassium-Argon Laser Experiment)

    Science.gov (United States)

    French, R. A.; Cohen, B. A.; Miller, J. S.

    2014-01-01

    The Potassium-Argon Laser Experiment( KArLE), is composed of two main instruments: a spectrometer as part of the Laser-Induced Breakdown Spectroscopy (LIBS) method and a Mass Spectrometer (MS). The LIBS laser ablates a sample and creates a plasma cloud, generating a pit in the sample. The LIBS plasma is measured for K abundance in weight percent and the released gas is measured using the MS, which calculates Ar abundance in mols. To relate the K and Ar measurements, total mass of the ablated sample is needed but can be difficult to directly measure. Instead, density and volume are used to calculate mass, where density is calculated based on the elemental composition of the rock (from the emission spectrum) and volume is determined by pit morphology. This study aims to reduce the uncertainty for KArLE by analyzing pit volume relationships in several analog materials and comparing methods of pit volume measurements and their associated uncertainties.

  4. Laser heating and magnetic compression of plasma in a fast solenoid

    International Nuclear Information System (INIS)

    Hoida, H.W.; Vlases, G.C.

    1978-01-01

    A low-β plasma column a few mm in diameter by 22 cm in length is heated by an axially directed CO 2 laser to a high-β state in a fast rising solenoidal field. Successful heating depends on proper timing between the laser pulse and rising field. Typical conditions attained are a line energy density of 6 J/cm, T-barapprox. =40 eV, and n/sub e/approx. =3 x 10 17 e - /cm 3 , with conditions quite uniform along the length. The heating suppresses instabilities which appear under certain conditions in the non-laser-heated case

  5. Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

    Directory of Open Access Journals (Sweden)

    Lkhamsuren Bayarjargal

    2011-09-01

    Full Text Available Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p; T stability, compressibility and hardness is described as obtained from experiments.

  6. Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

    Science.gov (United States)

    Friedrich, Alexandra; Winkler, Björn; Juarez-Arellano, Erick A.; Bayarjargal, Lkhamsuren

    2011-01-01

    Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments. PMID:28824101

  7. Conceptual design of bend, compression, and final focus components of ILSE [Induction Linac System Experiment

    International Nuclear Information System (INIS)

    Lee, E.P.; Fong, C.; Mukherjee, S.; Thur, W.

    1989-03-01

    The Induction Linac System Experiment (ILSE) includes a 180/degree/ bend system, drift compression line and a final focus, which test the analogous features of a heavy ion driver for inertial fusion. These components are novel in their transport of a space-charge-dominated ion beam with large head-to-tail velocity tilt. Their conceptual design is presented, including calculations of the beam envelope, momentum dispersion, and engineering design of magnets, vacuum system, diagnostics, alignment, and support. 3 refs., 5 figs

  8. Measurement of the fast electron distribution in laser-plasma experiments in the context of the 'fast ignition' approach to inertial confinement fusion

    International Nuclear Information System (INIS)

    Batani, Dimitri; Morace, Alessio

    2010-01-01

    The recent 'fast ignition approach' to ICF relies on the presence of fast electrons to provide the 'external' ignition spark triggering the nuclear fusion reaction in the compressed core of a thermonuclear target. Such fast electron beam is produced by the interaction of a short-pulse high-intensity laser with the target itself. In this context, it becomes essential to characterize the density of fast electrons and their average energy (i.e. the 'laser to fast electron' energy conversion efficiency) but also the finer details of the velocity and angular distribution. In this work we will discuss several techniques used to determine the fast electron distribution function.

  9. Observation of the charge neutrality of the ions from target short-pulse laser interaction experiments

    International Nuclear Information System (INIS)

    Yasuike, Kazuhito

    2003-01-01

    Intended to simulate the early stage of the plasma (preformed plasma) formation in the higher (10 20 W cm -2 ) intensity experiments (in which the plasma density profile rules laser absorption thus conversion efficiency from laser into hot electrons, ions and x-rays) experiments using solid target were done under a peak intensity (main laser pulse) of up to ∼10 15 W cm -2 and pre-pulse and pedestal intensity of ∼10 3 times lower than main pulse. With pedestal, significant enhancement of laser absorption was observed with pedestal condition. Charge neutralization of the ions from the plasma was measured by biased charge collectors. Earlier part of the ion were almost un-neutralized in with or without pedestal condition, and the later part of the ions (≤ few keV) were partially neutralized (≥40%). These not-perfect charge neutralization results is different from the longer nano-seconds pulse experimental results. (author)

  10. Development of a high repetition rate laser-plasma accelerator for ultra-fast electron diffraction experiments

    International Nuclear Information System (INIS)

    Beaurepaire, B.

    2009-01-01

    Electronic microscopy and electron diffraction allowed the understanding of the organization of atoms in matter. Using a temporally short source, one can measure atomic displacements or modifications of the electronic distribution in matter. To date, the best temporal resolution for time resolved diffraction experiments is of the order of a hundred femto-seconds (fs). Laser accelerators are good candidates to reach the femtosecond temporal resolution in electron diffraction experiments. Such accelerators used to work at a low repetition rate, so that it was necessary to develop a new one operating at a high repetition rate in order to accumulate a large amount of data. In this thesis, a laser-plasma accelerator operating at the kHz repetition rate was developed and built. This source generates electron bunches at 100 keV from 3 mJ and 25 fs laser pulses. The physics of the acceleration has been studied, and the effect of the laser wavefront on the electron transverse distribution has been demonstrated. (author)

  11. Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-Ray Preheat

    International Nuclear Information System (INIS)

    Colvin, Jeffrey D.; Kalantar, Daniel H.

    2006-01-01

    To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, <<1013 W/cm2, compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flash-coating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe

  12. Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-ray Preheat

    International Nuclear Information System (INIS)

    Colvin, J D; Kalantar, D H

    2005-01-01

    To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, 13 W/cm 2 , compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flashcoating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe

  13. The proceedings of the 1st international workshop on laboratory astrophysics experiments with large lasers

    International Nuclear Information System (INIS)

    Remington, B.A.; Goldstein, W.H.

    1996-01-01

    The world has stood witness to the development of a number of highly sophisticated and flexible, high power laser facilities (energies up to 50 kJ and powers up to 50 TW), driven largely by the world-wide effort in inertial confinement fusion (ICF). The charter of diagnosing implosions with detailed, quantitative measurements has driven the ICF laser facilities to be exceedingly versatile and well equipped with diagnostics. Interestingly, there is considerable overlap in the physics of ICF and astrophysics. Both typically involve compressible radiative hydrodynamics, radiation transport, complex opacities, and equations of state of dense matter. Surprisingly, however, there has been little communication between these two communities to date. With the recent declassification of ICF in the USA, and the approval to commence with construction of the next generation ''superlasers'', the 2 MJ National Ignition Facility in the US, and its equivalent, the LMJ laser in France, the situation is ripe for change. . Given the physics similarities that exist between ICF and astrophysics, one strongly suspects that there should exist regions of overlap where supporting research on the large lasers could be beneficial to the astrophysics community. As a catalyst for discussions to this end, Lawrence Livermore National Laboratory sponsored this workshop. Approximately 100 scientists attended from around the world, representing eight countries: the USA, Canada, UK, France, Germany, Russia, Japan, and Israel. A total of 30 technical papers were presented. The two day workshop was divided into four sessions, focusing on nonlinear hydrodynamics, radiative hydrodynamics, radiation transport, and atomic physics-opacities. Copies of the presentations are contained in these proceedings

  14. The proceedings of the 1st international workshop on laboratory astrophysics experiments with large lasers

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B.A.; Goldstein, W.H. [eds.

    1996-08-09

    The world has stood witness to the development of a number of highly sophisticated and flexible, high power laser facilities (energies up to 50 kJ and powers up to 50 TW), driven largely by the world-wide effort in inertial confinement fusion (ICF). The charter of diagnosing implosions with detailed, quantitative measurements has driven the ICF laser facilities to be exceedingly versatile and well equipped with diagnostics. Interestingly, there is considerable overlap in the physics of ICF and astrophysics. Both typically involve compressible radiative hydrodynamics, radiation transport, complex opacities, and equations of state of dense matter. Surprisingly, however, there has been little communication between these two communities to date. With the recent declassification of ICF in the USA, and the approval to commence with construction of the next generation ``superlasers``, the 2 MJ National Ignition Facility in the US, and its equivalent, the LMJ laser in France, the situation is ripe for change. . Given the physics similarities that exist between ICF and astrophysics, one strongly suspects that there should exist regions of overlap where supporting research on the large lasers could be beneficial to the astrophysics community. As a catalyst for discussions to this end, Lawrence Livermore National Laboratory sponsored this workshop. Approximately 100 scientists attended from around the world, representing eight countries: the USA, Canada, UK, France, Germany, Russia, Japan, and Israel. A total of 30 technical papers were presented. The two day workshop was divided into four sessions, focusing on nonlinear hydrodynamics, radiative hydrodynamics, radiation transport, and atomic physics-opacities. Copies of the presentations are contained in these proceedings.

  15. Using a cover layer to improve the damage resistance of gold-coated gratings induced by a picosecond pulsed laser

    Science.gov (United States)

    Xia, Zhilin; Wu, Yihan; Kong, Fanyu; Jin, Yunxia

    2018-04-01

    The chirped pulse amplification (CPA) technology is the main approach to achieve high-intensity short-pulse laser. Diffraction gratings are good candidates for stretching and compressing laser pulses in CPA. In this paper, a kind of gold-coated grating has been prepared and its laser damage experiment has been performed. The results reflect that the gratings laser damage was dominated by thermal ablation due to gold films or inclusions absorption and involved the deformation or eruption of the gold film. Based on these damage phenomena, a method of using a cover layer to prevent gold films from deforming and erupting has been adopted to improve the gold-coated gratings laser damage threshold. Since the addition of a cover layer changes the gratings diffraction efficiency, the gratings structure has been re-optimized. Furthermore, according to the calculated thermal stress distributions in gratings with optimized structures, the cover layer was demonstrated to be helpful for improving the gratings laser damage resistance if it is thick enough.

  16. Exploring compression techniques for ROOT IO

    Science.gov (United States)

    Zhang, Z.; Bockelman, B.

    2017-10-01

    ROOT provides an flexible format used throughout the HEP community. The number of use cases - from an archival data format to end-stage analysis - has required a number of tradeoffs to be exposed to the user. For example, a high “compression level” in the traditional DEFLATE algorithm will result in a smaller file (saving disk space) at the cost of slower decompression (costing CPU time when read). At the scale of the LHC experiment, poor design choices can result in terabytes of wasted space or wasted CPU time. We explore and attempt to quantify some of these tradeoffs. Specifically, we explore: the use of alternate compressing algorithms to optimize for read performance; an alternate method of compressing individual events to allow efficient random access; and a new approach to whole-file compression. Quantitative results are given, as well as guidance on how to make compression decisions for different use cases.

  17. ICF related experiments at CEL-V

    International Nuclear Information System (INIS)

    Andre, M.; Coutant, J.; Dautray, R.; Decroisette, M.; Duborgel, B.; Lachkar, J.; Ouvry, J.; Schurtz, G.; Watteau, J.P.

    1991-01-01

    Implosion experiments performed at Centre d'Etudes de Limeil-Valenton in the indirect drive scheme using the two-beams Nd glass laser facility Phebus at the energy level ≅ 6 kJ (blue light) are presented. A final density of compressed DT close to 100 ρ 0 has been obtained. Phebus has also been equipped with an optical fibre oscillator, to study the effect of a smoothing technique on coupling processes: at 0.53 μm, absorption efficiency is increased by ≅15-20%. With the eight beams Octal laser, hydrodynamic instabilities development in accelerated planar targets has been investigated both for direct and indirect drive. Atomic physics in laser plasmas is also deeply studied; a particular effort has been made on absorption spectroscopy which is a powerful diagnostic of ionization dynamics in cold and dense plasmas. In order to reach fuel ignition conditions, much powerful lasers, in the range of megajoule, will be needed. Their design needs further technological developments in order to reduce the capital cost. At Limeil, we work mainly on high damage threshold optical coatings, using the sol-gel process, high quality - low cost mirror fabrication, using the replica technics and incoherent laser pulse generation for beam smoothing

  18. Effect of the laser wavelength: A long story of laser-plasma interaction physics for Inertial Confinement Fusion Teller Medal Lecture

    Directory of Open Access Journals (Sweden)

    Labaune Christine

    2013-11-01

    Full Text Available Laser-driven Inertial Confinement Fusion (ICF relies on the use of high-energy laser beams to compress and ignite a thermonuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources–combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-term program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.

  19. Effect of the laser wavelength: A long story of laser-plasma interaction physics for Inertial Confinement Fusion Teller Medal Lecture

    Science.gov (United States)

    Labaune, Christine

    2016-10-01

    Laser-driven Inertial Confinement Fusion (ICF) relies on the use of high-energy laser beams to compress and ignite a the1monuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources-combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-te1m program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.

  20. Shock compression behavior of bi-material powder composites with disparate melting temperatures

    International Nuclear Information System (INIS)

    Sullivan, Kyle T.; Swift, Damian; Barham, Matthew; Stölken, James; Kuntz, Joshua; Kumar, Mukul

    2014-01-01

    Laser driven experiments were used to investigate the shock compression behavior of powder processed Bismuth/Tungsten (Bi/W) composite samples. The constituents provide different functionality to the composite behavior as Bi could be shock melted at the pressures attained in this work, while the W could not. Samples were prepared by uniaxial pressing, and the relative density was measured as a function of particle size, applied pressure, and composition for both hot and cold pressing conditions. This resulted in sample densities between 73% and 99% of the theoretical maximum density, and also noticeable differences in microstructure in the hot and cold pressed samples. The compression waves were generated with a 1.3 × 1.3 mm square spot directly onto the surface of the sample, using irradiances between 10 12 and 10 13  W/cm 2 , which resulted in calculated peak pressures between 50 and 150 GPa within a few micrometers. Sample recovery and post-mortem analysis revealed the formation of a crater on the laser drive surface, and the depth of this crater corresponded to the depth to which the Bi had been melted. The melt depth was found to be primarily a function of residual porosity and composition, and ranged from 167 to 528 μm. In general, a higher porosity led to a larger melt depth. Direct numerical simulations were performed, and indicated that the observed increase in melt depth for low-porosity samples could be largely attributed to increased heating associated with work done for pore collapse. However, the relative scaling was sensitive to composition, with low volume fraction Bi samples exhibiting a much stronger dependence on porosity than high Bi content samples. Select samples were repeated using an Al foil ablator, but there were no noticeable differences ensuring that the observed melting was indeed pressure-driven and was not a result of direct laser heating. The resultant microstructures and damage near the spall surface were also investigated