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Sample records for array implosion obtained

  1. Compact wire array sources: power scaling and implosion physics.

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Jason Dimitri; Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, M. C.; Vesey, Roger Alan; Waisman, Eduardo M.; Ivanov, V. V. (University of Nevada - Reno, Reno, NV); Esaulov, Andrey A. (University of Nevada - Reno, Reno, NV); Ampleford, David J.; Cuneo, Michael Edward; Kantsyrev, Victor Leonidovich (University of Nevada - Reno, Reno, NV); Coverdale, Christine Anne; Rudakov, L. I. (Icarus Research, Bethesda, MD); Jones, Brent Manley; Safronova, Alla S. (University of Nevada - Reno, Reno, NV); Vigil, Marcelino Patricio

    2008-09-01

    A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at {approx}5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref. [1], which studied planar arrays at {approx}3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/?s implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we

  2. Radiation characteristics and implosion dynamics of tungsten wire array Z-pinches on the YANG accelerator

    Institute of Scientific and Technical Information of China (English)

    Huang Xian-Bin; Chen Guang-Hua; Zhang Zheng-Wei; Ouyang Kai; Li Jun; Zhang Zhao-Hui; Zhou Rong-Guo; Wang Gui-Lin; Yang Li-Bing; Li Jing; Zhou Shao-Tong; Ren Xiao-Dong; Zhang Si-Qun; Dan Jia-Kun; Cai Hong-Chun; Duan Shu-Chao

    2012-01-01

    We investigated the radiation characteristics and implosion dynamics of low-wire-number cylindrical tungsten wire array Z-pinches on the YANG accelerator with a peak current 0.8-1.1 M A and a rising time~90 ns.The arrays are made up of(8-32)x5 μm wires 6/10 mm in diameter and 15 mm in height.The highest X-ray power obtained in the experiments was about 0.37 TW with the total radiation energy~13 kJ and the energy conversion efficiency~9%(24x5 μm wires,6 mm in diameter).Most of the X-ray emissions from tungsten Z-pinch plasmas were distributed in the spectral band of 100-600 eV,peaked at 250 and 375 eV.The dominant wavelengths of the wire ablation and the magneto-Rayleigh-Taylor instability were found and analyzed through measuring the time-gated self-emission and laser interferometric images.Through analyzing the implosion trajectories obtained by an optical streak camera,the run-in velocities of the Z-pinch plasmas at the end of the implosion phase were determined to be about(1.3-2.1)x 107 cm/s.

  3. Implosion dynamics and x-ray generation in small-diameter wire-array Z pinches.

    Science.gov (United States)

    Ivanov, V V; Sotnikov, V I; Kindel, J M; Hakel, P; Mancini, R C; Astanovitskiy, A L; Haboub, A; Altemara, S D; Shevelko, A P; Kazakov, E D; Sasorov, P V

    2009-05-01

    It is known from experiments that the radiated x-ray energy appears to exceed the calculated implosion kinetic energy and Spitzer resistive heating [C. Deeney, Phys. Rev. A 44, 6762 (1991)] but possible mechanisms of the enhanced x-ray production are still being discussed. Enhanced plasma heating in small-diameter wire arrays with decreased calculated kinetic energy was investigated, and a review of experiments with cylindrical arrays of 1-16 mm in diameter on the 1 MA Zebra generator is presented in this paper. The implosion and x-ray generation in cylindrical wire arrays with different diameters were compared to find a transition from a regime where thermalization of the kinetic energy is the prevailing heating mechanism to regimes with other dominant mechanisms of plasma heating. Loads of 3-8 mm in diameter generate the highest x-ray power at the Zebra generator. The x-ray power falls in 1-2 mm loads which can be linked to the lower efficiency of plasma heating with the lack of kinetic energy. The electron temperature and density of the pinches also depend on the array diameter. In small-diameter arrays, 1-3 mm in diameter, ablating plasma accumulates in the inner volume much faster than in loads of 12-16 mm in diameter. Correlated bubblelike implosions were observed with multiframe shadowgraphy. Investigation of energy balance provides evidence for mechanisms of nonkinetic plasma heating in Z pinches. Formation and evolution of bright spots in Z pinches were studied with a time-gated pinhole camera. A comparison of x-ray images with shadowgrams shows that implosion bubbles can initiate bright spots in the pinch. Features of the implosions in small-diameter wire arrays are discussed to identify mechanisms of energy dissipation.

  4. The Physics of Long-Pulse Wire Array Z-Pinch Implosions

    Energy Technology Data Exchange (ETDEWEB)

    DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; PETERSON,D.L.

    1999-12-14

    Recent improvements in z-pinch wire array load design at Sandia National Laboratories have led to a substantial increase in pinch performance as measured by radiated powers of up to 280 TW in 4 ns and 1.8 MJ of total radiated energy. Next generation, higher current machines will allow for larger mass arrays and comparable or higher velocity implosions to be reached, possibly extending these result.dis the current is pushed above 20 MA, conventional machine design based on a 100 ns implosion time results in higher voltages, hence higher cost and power flow risk. Another approach, which shifts the risk to the load configuration, is to increase the implosion time to minimize the voltage. This approach is being investigated in a series of experimental campaigns on the Saturn and Z machines. In this paper, both experimental and two dimensional computational modeling of the fist long implosion Z experiments will be presented. The experimental data shows broader pulses, lower powers, and larger pinch diameters compared to the corresponding short pulse data. By employing a nested array configuration, the pinch diameter was reduced by 50% with a corresponding increase in power of > 30%. Numerical simulations suggest load velocity is the dominating mechanism behind these results.

  5. Experiments with a Gas-Puff-On-Wire-Array Load on the GIT-12 Generator for Al K-shell Radiation Production at Microsecond Implosion Times

    Science.gov (United States)

    Shishlov, Alexander V.; Baksht, Rina B.; Chaikovsky, Stanislav A.; Fedunin, Anatoly V.; Fursov, Fedor I.; Kovalchuk, Boris M.; Kokshenev, Vladimir A.; Kurmaev, Nikolai E.; Labetsky, Aleksey Yu.; Oreshkin, Vladimir I.; Rousskikh, Alexander G.; Lassalle, Francis; Bayol, Frederic

    2006-01-01

    Results of the experiments carried out on the GIT-12 generator at the current level of 3.5 MA and the Z-pinch implosion times from 700 ns to 1.1 μs are presented. A multi-shell (triple-shell) load configuration with the outer gas puffs (neon) and the inner wire array (aluminum) was used in the experiments. In the course of the research, implosion dynamics of the triple-shell z-pinch was studied, and the radiation yield in the spectral range of neon and aluminum K-lines have been measured. Optimization of the inner wire array parameters aimed at obtaining the maximum aluminum K-shell radiation yield has been carried out. As a result of optimization of the gas-puff-on-wire-array Z-pinch load, the aluminum K-shell radiation yield (hv> 1.55 keV) up to 4 kJ/cm in the radiation pulse with FWHM less than 30 ns has been obtained. Comparison of the experimental results with the results of preliminary 1D RMHD simulations allows a conclusion that at least 2/3 of the generator current is switched from a gas puff to an aluminum wire array. The radiation yield in the spectral range of neon K-lines (0.92-1.55 keV) increases considerably in the shots with the inner wire array in comparison with the shots carried out with the outer gas puffs only. The radiation yield in the spectral range above 1 keV registered in the experiments reached 10 kJ/cm. The presence of a high portion of the neon plasma inside an inner wire array can limit the radiation yield in the spectral range above 1.55 keV.

  6. Effect of the Initial Load Parameters on the K-shell Output of Al Planar Wire Arrays Operating in the Microsecond Implosion Regime

    Science.gov (United States)

    Shishlov, A.; Chaikovsky, S.; Fedunin, A.; Fursov, F.; Kokshenev, V.; Kurmaev, N.; Labetsky, A.; Oreshkin, V.; Rousskikh, A.; Labetskaya, N.

    2009-01-01

    A set of microsecond implosion experiments was carried on the GIT-12 generator to study the radiative performance of Al planar wire arrays. The load parameters such as a wire diameter, a gap between the wires, the number of wires, and the total planar wire mass and width were varied during the experiments, however the implosion time and the peak implosion current were almost the same for all load configurations. This ensured equal energy deposition to the plasma due to kinetic mechanisms for all load configurations. Two implosion regimes with the implosion times of 1050 ns and 850 ns were investigated. The experimental data on the K-shell radiation yield and power at varying load parameters are presented.

  7. Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

    International Nuclear Information System (INIS)

    We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to ∼5.8 mg. The driver utilized was the ∼20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of ∼375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

  8. Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, Michael G.; Stygar, William A.; Sinars, Daniel B.; Cuneo, Michael E.; Nash, Thomas J.; Chandler, Gordon A.; Keith Matzen, M.; Porter, John L.; Struve, Kenneth W.; McDaniel, Dillon H. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Deeney, Christopher E. [National Nuclear Security Administration, Washington, D.C. 20585 (United States); Douglas, Melissa R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chittenden, Jerry [Imperial College, London, SW and 2BW (United Kingdom)

    2011-11-15

    We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to {approx}5.8 mg. The driver utilized was the {approx}20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of {approx}375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

  9. Study of ablation and implosion stages in wire arrays using coupled ultraviolet and X-ray probing diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, A. A.; Ivanov, V. V.; Astanovitskiy, A. L.; Wiewior, P. P.; Chalyy, O. [University of Nevada Reno, Reno, Nevada 89557 (United States); Papp, D. [University of Nevada Reno, Reno, Nevada 89557 (United States); ELI-ALPS, ELI-Hu Nkft., H-6720 Szeged (Hungary)

    2015-11-15

    Star and cylindrical wire arrays were studied using laser probing and X-ray radiography at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. The Leopard laser provided backlighting, producing a laser plasma from a Si target which emitted an X-ray probing pulse at the wavelength of 6.65 Å. A spherically bent quartz crystal imaged the backlit wires onto X-ray film. Laser probing diagnostics at the wavelength of 266 nm included a 3-channel polarimeter for Faraday rotation diagnostic and two-frame laser interferometry with two shearing interferometers to study the evolution of the plasma electron density at the ablation and implosion stages. Dynamics of the plasma density profile in Al wire arrays at the ablation stage were directly studied with interferometry, and expansion of wire cores was measured with X-ray radiography. The magnetic field in the imploding plasma was measured with the Faraday rotation diagnostic, and current was reconstructed.

  10. The effect of current prepulse on wire array Z-pinch implosions

    International Nuclear Information System (INIS)

    The effect of a prepulse current on the behavior of wire array Z pinches is investigated. The experiments were performed on the MAGPIE generator (1 MA peak current at 240 ns) [I. Mitchell, J. M. Bayley, J. P. Chittenden et al., Rev. Sci. Instrum. 67, 1533 (1996)]. A linear ramp current, ∼500-ns long, was used as a prepulse. The array consisted of 32 15-μm aluminum wires, 23-mm long arranged in a 16-mm diameter circle. With a prepulse of 1 kA/wire, a low density precursor plasma column (ne∼2x1017 cm-3) is formed on the array axis before the start of the main current. Later, the soft x-ray emission shows the growth of an m=1 helical instability in the precursor plasma, which indicates the presence of a current. Without a prepulse current, the precursor plasma on axis is uniform and does not show any instability. The x-ray pulse at stagnation on axis is at least 30 times smaller with a prepulse current than without

  11. Measurement and modeling of the implosion of wire arrays with seeded instabilities

    International Nuclear Information System (INIS)

    In order to study wire array Z-pinch instabilities, perturbations have been seeded by etching 15 μm diameter aluminum wires to introduce 20% modulations in radius with a controlled axial wavelength. These perturbations seed additional imploding structures that are studied experimentally on the 1 MA, 250 ns MAGPIE generator [S. V. Lebedev et al., Plasma Phys. Control. Fusion 47, A91 (2005)] and with three-dimensional magnetohydrodynamic calculations using the ALEGRA-HEDP [A. C. Robinson and C. J. Garasi, Comput. Phys. Commun. 164, 408 (2004)] and GORGON [J. P. Chittenden et al., Plasma Phys. Control. Fusion 46, B457 (2004)] codes. Simulations indicate that current path nonuniformity at discontinuities in the wire radius result in perturbation-induced magnetic bubble formation. Imploding bubbles originating from discontinuities are observed experimentally, and their collision on axis determines the start of the main x-ray pulse rise. These mechanisms likely govern dynamics of standard wire array Z pinches, and tailoring the profile of imploding mass may allow x-ray pulse shaping for inertial confinement fusion applications

  12. Implosion hydrodynamics

    International Nuclear Information System (INIS)

    Implosion hydrodynamics are examined, from the conditions in the imploded target to the initial target configuration and the driver performance. The subject is discussed under the topic headings: inertial configuration, thermonuclear fusion processes, ignition model, shock waves, acceleration by a constant pressure, spherical shock waves and imploding flows, drive pressure requirements, pulse shaping, pressure generation by lasers and ion beams, symmetry and hydrodynamic stability and typical target designs. (U.K.)

  13. Implosions and hypertoric geometry

    DEFF Research Database (Denmark)

    Dancer, A.; Kirwan, F.; Swann, A.

    2013-01-01

    The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion.......The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion....

  14. New Regimes of Implosions of Larger Sized Wire Arrays With and Without Modified Central Plane at 1.5-1.7 MA Zebra

    Science.gov (United States)

    Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Stafford, A.; Keim, S. F.; Petkov, E. E.; Lorance, M.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

    2013-10-01

    The recent experiments at 1.5-1.7 MA on Zebra at UNR with larger sized planar wires arrays (compared to the wire loads at 1 MA current) have demonstrated higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions. Such multi-planar wire arrays had two outer wire planes from mid-Z material to create a global magnetic field (gmf) and mid-Z plasma flow between them. Also, they included a modified central plane with a few Al wires at the edges to influence gmf and to create Al plasma flow in the perpendicular direction. The stationary shock waves which existed over tens of ns on shadow images and the early x-ray emissions before the PCD peak on time-gated spectra were observed. The most recent experiments with similar loads but without the central wires demonstrated a very different regime of implosion with asymmetrical jets and no precursor formation. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  15. Study of soft X-ray emission during wire array implosion under plasma focus conditions at the PF-3 facility

    Energy Technology Data Exchange (ETDEWEB)

    Dan’ko, S. A. [National Research Centre Kurchatov Institute (Russian Federation); Mitrofanov, K. N., E-mail: mitrofan@triniti.ru [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Krauz, V. I.; Myalton, V. V.; Zhuzhunashvili, A. I.; Vinogradov, V. P.; Kharrasov, A. M.; Anan’ev, S. S.; Vinogradova, Yu. V.; Kalinin, Yu. G. [National Research Centre Kurchatov Institute (Russian Federation)

    2015-11-15

    Results of measurements of soft X-ray emission with photon energies of <1 keV under conditions of a plasma focus (PF) experiment are presented. The experiments were carried out at the world’s largest PF device—the PF-3 Filippov-type facility (I ⩽ 3 MA, T/4 ≈ 15–20 µs, W{sub 0} ⩽ 3 MJ). X-ray emission from both a discharge in pure neon and with a tungsten wire array placed on the axis of the discharge chamber was detected. The wire array imploded under the action of the electric current intercepted from the plasma current sheath of the PF discharge in neon. The measured soft X-ray powers from a conventional PF discharge in gas and a PF discharge in the presence of a wire array were compared for the first time.

  16. Diagnostics for Z-pinch implosion experiments on PTS

    Energy Technology Data Exchange (ETDEWEB)

    Ren, X. D., E-mail: amosrxd@163.com; Huang, X. B., E-mail: amosrxd@163.com; Zhou, S. T., E-mail: amosrxd@163.com; Zhang, S. Q., E-mail: amosrxd@163.com; Dan, J. K., E-mail: amosrxd@163.com; Li, J., E-mail: amosrxd@163.com; Cai, H. C., E-mail: amosrxd@163.com; Wang, K. L., E-mail: amosrxd@163.com; Ouyang, K., E-mail: amosrxd@163.com; Xu, Q., E-mail: amosrxd@163.com; Duan, S. C., E-mail: amosrxd@163.com; Chen, G. H., E-mail: amosrxd@163.com; Wang, M., E-mail: amosrxd@163.com; Feng, S. P., E-mail: amosrxd@163.com; Yang, L. B., E-mail: amosrxd@163.com; Xie, W. P., E-mail: amosrxd@163.com; Deng, J. J., E-mail: amosrxd@163.com [Key Lab of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang, Sichuan 621999 (China)

    2014-12-15

    The preliminary experiments of wire array implosion were performed on PTS, a 10 MA z-pinch driver with a 70 ns rise time. A set of diagnostics have been developed and fielded on PTS to study pinch physics and implosion dynamics of wire array. Radiated power measurement for soft x-rays was performed by multichannel filtered x-ray diode array, and flat spectral responses x-ray diode detector. Total x-ray yield was measured by a calibrated, unfiltered nickel bolometer which was also used to obtain pinch power. Multiple time-gated pinhole cameras were used to produce spatial-resolved images of x-ray self-emission from plasmas. Two time-integrated pinhole cameras were used respectively with 20-μm Be filter and with multilayer mirrors to record images produced by >1-keV and 277±5 eV self-emission. An optical streak camera was used to produce radial implosion trajectories, and an x-ray streak camera paired with a horizontal slit was used to record a continuous time-history of emission with one-dimensional spatial resolution. A frequency-doubled Nd:YAG laser (532 nm) was used to produce four frame laser shadowgraph images with 6 ns time interval. We will briefly describe each of these diagnostics and present some typical results from them.

  17. Experimental study of implosion dynamics of multi-material nested wire-arrays on S-300 pulsed power generator

    NARCIS (Netherlands)

    Chernenko, AS; Smirnov, VP; Kingsep, AS; Kalinin, YG; Bakshaev, YL; Bartov, AV; Blinov, PI; Danko, SA; Dubas, LG; Korelskii, AV; Korolev, VD; Mizhiritsky, [No Value; Shaskov, AY; Ustroev, GI; Li, ZH; Hua, XS; Feng, SP; Guo, C; Jiang, SL; Ning, C; Peng, XJ; Song, FJ; Xu, RK; Xu, ZP; Yan, CL; Yang, JL; Yang, LB; Cai, HC

    2004-01-01

    On "S-300" generator (700 W, 4 MA, 70 ns) at the Kurchatov Institute, the experimental studies with multi-material wire array units are carried on aimed at creating the powerful X-ray source. The development of new diagnostic methods would definitely contribute to attain new data, which could help i

  18. An Update on Phased Array Results Obtained on the GE Counter-Rotating Open Rotor Model

    Science.gov (United States)

    Podboy, Gary; Horvath, Csaba; Envia, Edmane

    2013-01-01

    Beamform maps have been generated from 1) simulated data generated by the LINPROP code and 2) actual experimental phased array data obtained on the GE Counter-rotating open rotor model. The beamform maps show that many of the tones in the experimental data come from their corresponding Mach radius. If the phased array points to the Mach radius associated with a tone then it is likely that the tone is a result of the loading and thickness noise on the blades. In this case, the phased array correctly points to where the noise is coming from and indicates the axial location of the loudest source in the image but not necessarily the correct vertical location. If the phased array does not point to the Mach radius associated with a tone then some mechanism other than loading and thickness noise may control the amplitude of the tone. In this case, the phased array may or may not point to the actual source. If the source is not rotating it is likely that the phased array points to the source. If the source is rotating it is likely that the phased array indicates the axial location of the loudest source but not necessarily the correct vertical location. These results indicate that you have to be careful in how you interpret phased array data obtained on an open rotor since they may show the tones coming from a location other than the source location. With a subsonic tip speed open rotor the tones can come form locations outboard of the blade tips. This has implications regarding noise shielding.

  19. S-300装置铝丝阵内爆X光辐射特性%Characteristics of soft X-ray emission generated in implosion of Al wire array Z-pinch experiments on S-300 facility

    Institute of Scientific and Technical Information of China (English)

    蒋世伦; 宁家敏; 夏广新; 徐荣昆

    2011-01-01

    零维模型负载优化设计制作的单层和双层铝丝阵负载,在俄罗斯S-300强流发生器上,利用"狭缝+闪烁体+光电探测器"X光功率测量系统对X光辐射特性参数进行了诊断.实验获得单层丝阵负载的辐射功率为(0.31±0.19)TW,辐射总能量为(16.93±7.45)kJ,脉宽为(18.41±5.00)ns;双层丝阵负载的辐射功率为(0.37±0.12)TW,辐射总能量为(16.40±3.99)kJ,脉宽为(13.45±3.50)ns.实验结果表明,双层丝阵负载辐射功率高于单层19.4%,信号脉宽窄4.96 ns.%An X-ray power measuring system composed of slit, scintillator and phototube is used to diagnose the characteristic parameters of soft X-ray generated in the implosion of Al wire array Z-pinch experiments on the S-300 facility at Kurchatov Institute. Wire array loads based on zero-dimension thin shell model are designed for experiments. For single wire array load, the experiment gets an X-ray power of (0.31±0.19) TW, total radiated energy of (16.40±7.45) kJ, and pulse width of (18. 41± 5.00) ns. For nested wire array load, an X-ray power of (0. 37±0. 12 ) TW, total radiated energy of (16.93±3.99) kJ, and pulse width of (13.45 ± 3.50) ns are achieved. The experimental results of different wire array loads show that the total energy achieved by nested wire array is 19.4% higher than that of single wire array, and the pulse width for nested wire array decreases by 4.96 ns compared to that for single wire array.

  20. Compton Radiography of ICF implosions

    Science.gov (United States)

    Tommasini, Riccardo

    2011-10-01

    Laser-produced, micro-wire backlighters in a point-projection geometry, generating X-ray photons with energies ranging from 50keV to 200 keV, have been used to record time-resolved 2D radiographs of the dense cold fuel surrounding the hot spot of inertial confinement fusion implosions at the OMEGA facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The radiographs have spatial and temporal resolution of ~10 μm and ~10 ps, respectively, and allow localized measurements of areal mass densities with 7% accuracy. The experimental results show 3D non-uniformities and lower than 1D expected areal densities attributed to drive asymmetries and hydroinstabilities. The areal density measurements from radiographs compare well to the values obtained from charged particle spectrometry. We are preparing similar experiments using this technique to obtain radiographs of cryogenic implosions at the National Ignition Facility. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  1. Diagnostic and quality-assurance tools for low-contrast images obtained from array detectors

    Science.gov (United States)

    Hatfield, D. B.; Sandel, Bill R.

    1993-01-01

    We investigate methods of estimating a background image frame for subtraction from a data frame for use when a more suitable measured background frame is not available. We define background as any signal component that is not attributable to the phenomenon currently under investigation. We describe a technique that is based on pixel-by-pixel least-squares regression of images for computing a background frame from available data. We argue that the same technique can be a useful quality-assurance tool for evaluating instrument performance. For example, it can help to separate image structure resulting from the reading process from structure resulting from the characteristics of the detector itself. We demonstrate that background estimation can be nontrivial by comparing the results of different background estimation procedures by using data obtained from a CCD array detector. We investigate the temperature-dependent contributions of the detector and readout electronics to the total signal as a demonstration of the diagnostic capabilities of least-squares image regression.

  2. Progress in symmetric ICF capsule implosions and wire-array z-pinch source physics for double z-pinch driven hohlraums

    International Nuclear Information System (INIS)

    Over the last several years, rapid progress has been made evaluating the double-z-pinch indirect-drive, inertial confinement fusion (ICF) high-yield target concept (Hammer et al 1999 Phys. Plasmas 6 2129). We have demonstrated efficient coupling of radiation from two wire-array-driven primary hohlraums to a secondary hohlraum that is large enough to drive a high yield ICF capsule. The secondary hohlraum is irradiated from two sides by z-pinches to produce low odd-mode radiation asymmetry. This double-pinch source is driven from a single electrical power feed (Cuneo et al 2002 Phys. Rev. Lett. 88 215004) on the 20 MA Z accelerator. The double z-pinch has imploded ICF capsules with even-mode radiation symmetry of 3.1 ± 1.4% and to high capsule radial convergence ratios of 14-21 (Bennett et al 2002 Phys. Rev. Lett. 89 245002; Bennett et al 2003 Phys. Plasmas 10 3717; Vesey et al 2003 Phys. Plasmas 10 1854). Advances in wire-array physics at 20 MA are improving our understanding of z-pinch power scaling with increasing drive current. Techniques for shaping the z-pinch radiation pulse necessary for low adiabat capsule compression have also been demonstrated.

  3. On the validity of tidal turbine array configurations obtained from steady-state adjoint optimisation

    OpenAIRE

    Jacobs, Christian T.; Piggott, Matthew D.; Kramer, Stephan C; Funke, Simon W.

    2016-01-01

    Extracting the optimal amount of power from an array of tidal turbines requires an intricate understanding of tidal dynamics and the effects of turbine placement on the local and regional scale flow. Numerical models have contributed significantly towards this understanding, and more recently, adjoint-based modelling has been employed to optimise the positioning of the turbines in an array in an automated way and improve on simple, regular man-made configurations. Adjoint-based optimisation o...

  4. Isochoric implosions for fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D S; Tabak, M

    2006-06-05

    Fast Ignition (FI) exploits the ignition of a dense, uniform fuel assembly by an external energy source to achieve high gain. In conventional ICF implosions, however, the fuel assembles as a dense shell surrounding a low density, high-pressure hotspot. Such configurations are far from optimal for FI. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942).] may be employed to implode a dense, quasi-uniform fuel assembly with minimal energy wastage in forming a hotspot. A scheme for realizing these specialized implosions in a practical ICF target is also described.

  5. On the validity of tidal turbine array configurations obtained from steady-state adjoint optimisation

    CERN Document Server

    Jacobs, Christian T; Kramer, Stephan C; Funke, Simon W

    2016-01-01

    Extracting the optimal amount of power from an array of tidal turbines requires an intricate understanding of tidal dynamics and the effects of turbine placement on the local and regional scale flow. Numerical models have contributed significantly towards this understanding, and more recently, adjoint-based modelling has been employed to optimise the positioning of the turbines in an array in an automated way and improve on simple, regular man-made configurations. Adjoint-based optimisation of high-resolution and ideally 3D transient models is generally a very computationally expensive problem. As a result, existing work on the adjoint optimisation of tidal turbine placement has been mostly limited to steady-state simulations in which very high, non-physical values of the background viscosity are required to ensure that a steady-state solution exists. However, such compromises may affect the reliability of the modelled turbines, their wakes and interactions, and thus bring into question the validity of the co...

  6. Isochoric Implosions for Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D S; Tabak, M

    2007-04-04

    Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. & Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm{sup 3} and areal density of 2.4 g=cm{sup 2} using 485 kJ of laser energy.

  7. First high dynamic range and high resolution images of the sky obtained with a diffractive Fresnel array telescope

    Science.gov (United States)

    Koechlin, Laurent; Rivet, Jean-Pierre; Deba, Paul; Serre, Denis; Raksasataya, Truswin; Gili, René; David, Jules

    2012-03-01

    This paper presents high contrast images of sky sources, obtained from the ground with a novel optical concept: Fresnel arrays. We demonstrate the efficiency of a small 20 cm prototype Fresnel array for making images with high brightness ratios, achieving contrasts up to 4 × 105 on sky sources such as Mars and its satellites, and the Sirius A-B couple. These validation results are promising for future applications in space, for example the 4 m array we have proposed to ESA in the frame of the "Call for a Medium-size mission opportunity for a launch in 2022". Fresnel imagers are the subject of a topical issue of Experimental Astronomy published in 2011, but only preliminary results were presented at the time. Making images of astronomical bodies requires an optical component to focus light. This component is usually a mirror or a lens, the quality of which is critical for sharp and high contrast images. However, reflection on a mirror and refraction through a lens are not the only ways to focus light: an alternative is provided by diffraction through binary masks (opaque foils with multiple precisely etched sub-apertures). Our Fresnel arrays are such diffractive focusers, they offer weight, price and size advantages over traditional optics in space-based astronomical instruments. This novel approach requires only void apertures of special shapes in an opaque material to form sharp images, thus avoiding the wavefront distortion, diffusion and spectral absorption associated with traditional optical media. In our setup, lenses and/or mirrors are involved only downstream (at small sizes) for focal instrumentation and chromatic correction. Fresnel arrays produce high contrast images, the resolution of which reaches the theoretical limit of diffraction. Unlike mirrors, they do not require high precision polishing or positioning, and can be used in a large domain of wavelengths from far IR to far UV, enabling the study of many science cases in astrophysics from exoplanet

  8. Simulations of fill tube effects on the implosion of high-foot NIF ignition capsules

    Science.gov (United States)

    Dittrich, T. R.; Hurricane, O. A.; Berzak-Hopkins, L. F.; Callahan, D. A.; Casey, D. T.; Clark, D.; Dewald, E. L.; Doeppner, T.; Haan, S. W.; Hammel, B. A.; Harte, J. A.; Hinkel, D. E.; Kozioziemski, B. J.; Kritcher, A. L.; Ma, T.; Nikroo, A.; Pak, A. E.; Parham, T. G.; Park, H.-S.; Patel, P. K.; Remington, B. A.; Salmonson, J. D.; Springer, P. T.; Weber, C. R.; Zimmerman, G. B.; Kline, J. L.

    2016-05-01

    Encouraging results have been obtained using a strong first shock during the implosion of carbon-based ablator ignition capsules. These “high-foot” implosion results show that capsule performance deviates from 1D expectations as laser power and energy are increased. A possible cause of this deviation is the disruption of the hot spot by jets originating in the capsule fill tube. Nominally, a 10 μm outside diameter glass (SiO2) fill tube is used in these implosions. Simulations indicate that a thin coating of Au on this glass tube may lessen the hotspot disruption. These results and other mitigation strategies will be presented.

  9. Multispectral x-ray imaging for core temperature and density maps retrieval in direct drive implosions

    International Nuclear Information System (INIS)

    We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the Omega laser facility using multimonochromatic x-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multispectral images distributed over a wide spectral range. Using argon as a dopant in the direct-drive filled plastic shells produces emission images in the Ar He-β and Ly-β spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multimonochromatic x-ray imagers in a quasiorthogonal line-of-sight configuration to allow tomographic reconstruction of the structure of the imploding core

  10. Implosion Source Development and Diego Garcia Reflections

    Energy Technology Data Exchange (ETDEWEB)

    Harben, P E; Boro, C

    2001-06-01

    Calibration of hydroacoustic stations for nuclear explosion monitoring is important for increasing monitoring capability and confidence from newly installed stations and from existing stations. Past work at Ascension Island has shown that ship-towed airguns can be effectively used for local calibrations such as sensor location, amplitude and phase response, and T-phase coupling in the case of T-phase stations. At regional and ocean-basin distances from a station, the calibration focus is on acoustic travel time, transmission loss, bathymetric shadowing, diffraction, and reflection as recorded at a particular station. Such station calibrations will lead to an overall network calibration that seeks to maximize detection, location, and discrimination capability of events with acoustic signatures. Active-source calibration of hydroacoustic stations at regional and ocean-basin scales has not been attempted to date, but we have made significant headway addressing how such calibrations could be accomplished. We have developed an imploding sphere source that can be used instead of explosives on research and commercial vessels without restriction. The imploding sphere has been modeled using the Lawrence Livermore National Laboratory hydrodynamic code CALE and shown to agree with field data. The need for boosted energy in the monitoring band (2-100 Hz) has led us to develop a 5-sphere implosion device that was tested in the Pacific Ocean earlier this year. Boosting the energy in the monitoring band can be accomplished by a combination of increasing the implosion volume (i.e. the 5-sphere device) and imploding at shallower depths. Although active source calibrations will be necessary at particular locations and for particular objectives, the newly installed Diego Garcia station in the Indian Ocean has shown that earthquakes can be used to help understand regional blockages and the locations responsible for observed hydroacoustic reflections. We have analyzed several events

  11. Direct-drive implosion physics: Results from OMEGA and the National Ignition Facility

    Science.gov (United States)

    Radha, P. B.; Goncharov, V. N.; Hohenberger, M.; Sangster, T. C.; Betti, R.; Craxton, R. S.; Edgell, D. H.; Epstein, R.; Froula, D. H.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Hu, S. X.; Seka, W.; Shvydky, A.; Skupsky, S.; Frenje, J. A.; Gatu-Johnson, M.; Petrasso, R. D.; Ma, T.; Le Pape, S.; Mackinnon, A. J.

    2016-03-01

    Direct-drive-implosion experiments from both OMEGA and the National Ignition Facility (NIF) are critical to gain confidence in ignition predictions on the NIF. Adequate performance of hydrodynamically scaled 1.8-MJ ignition designs must be obtained on OMEGA at 26 kJ. Implosions on the NIF must be used to identify and mitigate the effect of laser-plasma interactions (LPI's) on hydrodynamic parameters at the NIF scale. Results from spherically driven OMEGA cryogenic implosion experiments are described. Mitigation of nonuniformity sources and cross-beam energy transfer (CBET) is important for improving target performance on OMEGA. Initial polar-driven implosion experiments on the NIF have provided valuable measurements of trajectory and symmetry. Simulations that include the effect of CBET more closely reproduce the observed velocity.

  12. Direct-drive implosion physics: Results from OMEGA and the National Ignition Facility

    Science.gov (United States)

    Radha, P. B.; Goncharov, V. N.; Hohenberger, M.; Sangster, T. C.; Betti, R.; Craxton, R. S.; Edgell, D. H.; Epstein, R.; Froula, D. H.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Hu, S. X.; Seka, W.; Shvydky, A.; Skupsky, S.; Frenje, J. A.; Gatu-Johnson, M.; Petrasso, R. D.; Ma, T.; Pape, S. Le; MacKinnon, A. J.

    2016-10-01

    Direct-drive-implosion experiments from both OMEGA and the National Ignition Facility (NIF) are critical to gain confidence in ignition predictions on the NIF. Adequate performance of hydrodynamically scaled 1.8-MJ ignition designs must be obtained on OMEGA at 26 kJ. Implosions on the NIF must be used to identify and mitigate the effect of laser-plasma interactions (LPI's) on hydrodynamic parameters at the NIF scale. Results from spherically driven OMEGA cryogenic implosion experiments are described. Mitigation of nonuniformity sources and cross-beam energy transfer (CBET) is important for improving target performance on OMEGA. Initial polar-driven implosion experiments on the NIF have provided valuable measurements of trajectory and symmetry. Simulations that include the effect of CBET more closely reproduce the observed velocity.

  13. Multi-channel laser Doppler velocimetry using a two-dimensional optical fiber array for obtaining instantaneous velocity distribution characteristics

    Science.gov (United States)

    Kyoden, Tomoaki; Yasue, Youichi; Ishida, Hiroki; Akiguchi, Shunsuke; Andoh, Tsugunobu; Takada, Yogo; Teranishi, Tsunenobu; Hachiga, Tadashi

    2015-01-01

    A laser Doppler velocimeter (LDV) has been developed that is capable of performing two-dimensional (2D) cross-sectional measurements. It employs two horizontal laser light sheets that intersect at an angle of 13.3°. Since the intersection region is thin, it can be used to approximately determine the 2D flow field. An 8 × 8 array of optical fibers is used to simultaneously measure Doppler frequencies at 64 points. Experiments were conducted to assess the performance of the LDV, and it was found to be capable of obtaining spatial and temporal velocity information at multiple points in a flow field. The technique is fast, noninvasive, and accurate over long sampling periods. Furthermore, its applicability to an actual flow field was confirmed by measuring the temporal velocity distribution of a pulsatile flow in a rectangular flow channel with an obstruction. The proposed device is thus a useful, compact optical instrument for conducting simultaneous 2D cross-sectional multipoint measurements.

  14. Long implosion experiments and simulations on the Saturn and Z machines

    International Nuclear Information System (INIS)

    By increasing the implosion time for Z-pinches from the canonical 100 ns to 200--300 ns, the complexity and power flow risks can be reduced for future higher current generators, assuming that the implosions still produce high energies and powers. The recent success of high wire number arrays and nested configurations have permitted load designs to be considered that could provide the necessary performance at the longer implosion times, i.e., can the authors challenge the conventional wisdom? At Sandia National Laboratory, two experimental campaigns (on Saturn and Z) plus two-dimensional MHD modeling have been performed to investigate the scaling of tungsten wire arrays to 150 to 250 ns implosion times. For the Saturn experiments 25 mm diameter, 240 tungsten wire arrays of increasing mass were used. A comparison with short pulse data shows similar powers, risetimes, final pinch diameters, and instability mode structure. For the same final implosion velocity, measured risetimes were faster than the equivalent short pulse. Fall times were much longer and correlated to late time on-axis dynamics. Simulations using the Mach2 code incorporated a cell-to-cell random density to initiate a Raleigh-Taylor instability, believed to dominate the implosion dynamics. The results of these simulations show that the rise time of the x-ray power correlates to the FWHM of the sheath and has a strong dependence on perturbation level. The mode evolution is similar to the short pulse simulation and experimental results are reproduced. Both simulations and theory suggest that in the long pulse mode, the wires have time to merge and form a more uniform shell prior to acceleration. Modeling of the long pulse Z data is in progress

  15. The high-foot implosion campaign on the National Ignition Facility

    International Nuclear Information System (INIS)

    The “High-Foot” platform manipulates the laser pulse-shape coming from the National Ignition Facility laser to create an indirect drive 3-shock implosion that is significantly more robust against instability growth involving the ablator and also modestly reduces implosion convergence ratio. This strategy gives up on theoretical high-gain in an inertial confinement fusion implosion in order to obtain better control of the implosion and bring experimental performance in-line with calculated performance, yet keeps the absolute capsule performance relatively high. In this paper, we will cover the various experimental and theoretical motivations for the high-foot drive as well as cover the experimental results that have come out of the high-foot experimental campaign. At the time of this writing, the high-foot implosion has demonstrated record total deuterium-tritium yields (9.3×1015) with low levels of inferred mix, excellent agreement with implosion simulations, fuel energy gains exceeding unity, and evidence for the “bootstrapping” associated with alpha-particle self-heating

  16. Design of foil implosion system for Pioneer I experiments

    International Nuclear Information System (INIS)

    A foil implosion system is described that integrates an explosive flux-compression generator, a flat plate feed section with power conditioning switches, and a vacuum electrode region containing a cylindrical foil/plasma load. Power conditioning, obtained with an explosive-driven plasma compression opening switch and explosive-actuated closing switches, provides a submicrosecond multimegampere pulse for the implosion of an aluminum plasma. The flat plate section is configured for bidirectional feed to the coaxial vacuum electrodes. Important considerations in the design of the vacuum power flow region include gap failure, feed symmetry, and radial diagnostic access. The system presently accommodates a foil radius of 3 cm. Innovative foil insertion and clamping techniques are also described

  17. Investigation of the Resistance and Inductance of Planar Wire Array Z-Pinch at the Qiangguang Accelerator

    Institute of Scientific and Technical Information of China (English)

    王亮平; 吴坚; 郭宁; 韩娟娟; 李沫; 李岩; 邱爱慈

    2012-01-01

    The resistance and inductance of a wire array during an implosion are very important parameters of interest to:researchers. A variety of inductances and resistances directly affect the kinetic energy and resistance heat energy coupled from a pulsed-power generator. In this paper, the inductance and resistance of a planar wire array during the Z-pinch process are analyzed. The inductance is calculated from the data obtained by a time-resolved soft X-ray framed camera, while the resistance is calculated through the voltage and the current of the wire array load combined with the variety of the inductance. The results show that the resistance of the load increases with the development of the implosion, and reaches its maximum at 0.29 ± 0.16Ω near the pinched time.

  18. Impact of the population implosion

    Energy Technology Data Exchange (ETDEWEB)

    Kilpatrick, J.J.

    1978-03-01

    Mr. Kilpatrick evaluates Paul R. Ehrlich's thesis that mankind will breed itself into oblivion. Mr. Ehrlich in his book, ''The Population Bomb,'' sees population control as the only answer to mass starvation in such countries as India, Africa, Central America, and China. Mr. Kilpatrick says the U.S. has drifted toward the goal of zero population growth, where the total births per woman have dropped to 1.8. In Denmark, Finland, Sweden, Belgium, West Germany, Great Britain, and Austria, the births per woman have dropped even lower than in the U.S. The decline in births is attributed to women joining the workforce, advancement of birth control measures, and high costs of medical care, housing, and education. Women marrying later and fashion are also factors. Zero population growth will have gross implications on the financial markets in the U.S. Pension systems will be directly affected. The author cites the dilemma of the Social Security system when a smaller proportion of young people are contributing to it. Household savings trends will alter; new construction, new plant and equipment investment, and consumer loans will have to be reconsidered. If the trend toward implosion continues and social services demand an increasing share of the Federal budget, other interests will have to yield and the author cites the budget for national defense as declining. Some prophets feel the population decline is nothing of concern, the author concludes. (MCW)

  19. Buoyancy instability of homologous implosions

    Science.gov (United States)

    Johnson, Bryan

    2015-11-01

    Hot spot turbulence is a potential contributor to yield degradation in inertial confinement fusion (ICF) capsules, although its origin, if present, remains unclear. In this work, a perturbation analysis is performed of an analytical homologous solution that mimics the hot spot and surrounding cold fuel during the late stages of an ICF implosion. It is shown that the flow is governed by the Schwarzschild criterion for buoyant stability, and that during stagnation, short wavelength entropy and vorticity fluctuations amplify by a factor exp (π |N0 | ts) , where N0 is the buoyancy frequency at stagnation and ts is the stagnation time scale. This amplification factor is exponentially sensitive to mean flow gradients and varies from 103-107 for realistic gradients. Comparisons are made with a Lagrangian hydrodynamics code, and it is found that a numerical resolution of ~ 30 zones per wavelength is required to capture the evolution of vorticity accurately. This translates to an angular resolution of ~(12 / l) ∘ , or ~ 0 .1° to resolve the fastest growing modes (Legendre mode l > 100).

  20. The numerical simulations of explosion and implosion in air: use of a modified Harten's TVD scheme

    Science.gov (United States)

    Liu, T. G.; Khoo, B. C.; Yeo, K. S.

    1999-10-01

    Numerical simulations of explosion and implosion in air are carried out with a modified Harten's TVD scheme. The new scheme has a high resolution for contact discontinuities in addition to maintaining the good features of Harten's TVD scheme. In the numerical experiment of spherical explosion in air, the second shock wave (which does not exist in the one-dimensional shock tube problem) and its subsequent implosion on the origin have been successfully captured. The positions of the main shock wave, the contact discontinuity and the second shock wave have shown satisfactory agreement with those predicted from previous analysis. The numerical results are also compared with those obtained experimentally. Finally, simulations of a cylindrical explosion and implosion in air are carried out. Results of the cylindrical implosion in air are compared with those of previous work, including the interaction of the reflected main shock wave with the contact discontinuity and the formation of a second shock wave. All these attest to the successful use of the modified Harten's TVD scheme for the simulations of shock waves arising from explosion and implosion. Copyright

  1. Studies of ablation pressure, ablative acceleration and ablative implosions

    International Nuclear Information System (INIS)

    Time and space resolved X-ray spectroscopy have been used to measure ablation rate and ablation pressure on plane targets irradiated by the first and second harmonics of Nd glass laser light. Streaked X-ray shadowgraphy has been applied to the study of ablatively imploded spherical shell targets uniformly irradiated by six 1.05 μm laser beams. The results give a direct measurement of shell acceleration and thus of ablation pressure and show evidence of fluid instability increasing as the shell ratio is varied from 10 to 100. A direct determination of implosion core density is also obtained. (author)

  2. Reproducibility of hohlraum-driven implosion symmetry on the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Kyrala G.A.

    2013-11-01

    Full Text Available Indirectly driven Symcap capsules are used at the NIF to obtain information about ignition capsule implosion performance, in particular shape. Symcaps replace the cryogenic fuel layer with an equivalent ablator mass and can be similarly diagnosed. Symcaps are good symmetry surrogates to an ignition capsule after the peak of the drive, radiation-hydrodynamics simulations predict that doping of the symcaps vary the behavior of the implosion. We compare the equatorial shapes of a symcap doped with Si or Ge, as well as examine the reproducibility of the shape measurement using two symcaps with the same hohlraum and laser conditions.

  3. The Los Alamos foil implosion project

    International Nuclear Information System (INIS)

    The goal of the Los Alamos foil implosion project is to produce an intense (>100 TW), multi-megajoule, laboratory soft x-ray source for material studies and fusion experiments. The concept involves the implosion of annular, current-carrying, cylindrical metallic plasmas via their self-magnetic forces. The project features inductive storage systems using both capacitor banks and high explosive-driven flux compression generators as prime energy sources. Fast opening switches are employed to shorten the electrical pulses. The program will be described and activities to date will be summarized

  4. Implosion chain reaction mitigation in underwater assemblies of photomultiplier tubes

    International Nuclear Information System (INIS)

    Since the accident with a cascade failure of photomultiplier tubes (PMTs) in the Super-Kamiokande experiment in 2001, the mechanical performance of large format semi-hemispherical PMTs has become a critical issue for large water Cherenkov detectors. The subject of this study is the survival of an assembled array of PMTs under significant hydrostatic pressure and subjected to shock waves caused by the failure of a single PMT. This paper details the results of the second stage of a R and D program focused on the design and testing of different PMT assemblies to mitigate the risk of a “chain-reaction” of PMT failures. The initial results show that our PMT assembly design can effectively reduce the magnitude of the shock wave. With the testing results in this paper and the hydrodynamic simulation calculation, we can further improve the design of PMT deployment to mitigate the risk of chain reactions caused by implosion induced shock waves

  5. Implosive therapy as a treatment for insomnia.

    Science.gov (United States)

    Carrera, R N; Elenewski, J J

    1980-07-01

    Previous research has suggested that insomnia is related positively to preoccupation with death. Introductory psychology students (N = 200) of both sexes who qualified as insomniacs were administered Implosive Therapy specifically targeted to fear of death, nonspecific Implosive Therapy, a relaxation procedure, or were assigned to a wait-control group. All three experimental treatments resulted in significant decreases in anxiety as measured by the Fear Survey Schedule II administered immediately after the experiment. The groups did not differ, however, before or after treatment on reported fear of death as measured by the Collett-Lester scale. On self-report measures collected 1 month after the experimental treatment, all groups, including the wait-control, showed a significant decrease in latency of sleep onset. Pairwise comparisons indicated that only the death implosion condition was significantly more effective than the wait-control. The finding was interpreted to mean that the death implosion produced a decrease in insomnia beyond the strong expectancy effects that resulted from all experimental treatments. The failure to observe changes in reported fear of death was attributed to Ss' anxiety-based reluctance to acknowledge openly such fear. PMID:7410572

  6. The implosion of cylindrical shell structures in a high-pressure water environment.

    Science.gov (United States)

    Ikeda, C M; Wilkerling, J; Duncan, J H

    2013-12-01

    The implosion of cylindrical shell structures in a high-pressure water environment is studied experimentally. The shell structures are made from thin-walled aluminium and brass tubes with circular cross sections and internal clearance-fit aluminium end caps. The structures are filled with air at atmospheric pressure. The implosions are created in a high-pressure tank with a nominal internal diameter of 1.77 m by raising the ambient water pressure slowly to a value, P c, just above the elastic stability limit of each shell structure. The implosion events are photographed with a high-speed digital movie camera, and the pressure waves are measured simultaneously with an array of underwater blast sensors. For the models with larger values of length-to-diameter ratio, L/D 0, the tubes flatten during implosion with a two-lobe (mode 2) cross-sectional shape. In these cases, it is found that the pressure wave records scale primarily with P c and the time scale [Formula: see text] (where R i is the internal radius of the tube and ρ is the density of water), whereas the details of the structural design produce only secondary effects. In cases with smaller values of L/D 0, the models implode with higher-mode cross-sectional shapes. Pressure signals are compared for various mode-number implosions of models with the same available energy, P c V , where V is the internal air-filled volume of the model. It is found that the pressure records scale well temporally with the time scale [Formula: see text], but that the shape and amplitudes of the pressure records are strongly affected by the mode number. PMID:24353473

  7. Fast batch injection analysis of H{sub 2}O{sub 2} using an array of Pt-modified gold microelectrodes obtained from split electronic chips

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, Bruno D.; Valerio, Jaqueline [Centro de Ciencias e Humanidades - Universidade Presbiteriana Mackenzie, Rua da Consolacao, 896, 01302-907 Sao Paulo, SP (Brazil); Angnes, Lucio [Departamento de Quimica Fundamental, Instituto de Quimica da USP, Av. Prof. Lineu Prestes, 748, 05508-000 Cidade Universitaria, Sao Paulo, SP (Brazil); Pedrotti, Jairo J., E-mail: jpedrotti@mackenzie.br [Centro de Ciencias e Humanidades - Universidade Presbiteriana Mackenzie, Rua da Consolacao, 896, 01302-907 Sao Paulo, SP (Brazil)

    2011-06-24

    Graphical abstract: Highlights: > An array of gold microelectrodes modified with Pt was used for batch injection analysis of H{sub 2}O{sub 2} in rainwater. > The microelectrode array (n = 14) was obtained from electronic chips developed for surface mounted device technology. > The analytical frequency of the method can attain 300 determinations per hour. > The volume-weighted mean concentration of H{sub 2}O{sub 2} in rainwater investigated (n = 25) was 14.2 {mu}mol L{sup -1}. - Abstract: A fast and robust analytical method for amperometric determination of hydrogen peroxide (H{sub 2}O{sub 2}) based on batch injection analysis (BIA) on an array of gold microelectrodes modified with platinum is proposed. The gold microelectrode array (n = 14) was obtained from electronic chips developed for surface mounted device technology (SMD), whose size offers advantages to adapt them in batch cells. The effect of the dispensing rate, volume injected, distance between the platinum microelectrodes and the pipette tip, as well as the volume of solution in the cell on the analytical response were evaluated. The method allows the H{sub 2}O{sub 2} amperometric determination in the concentration range from 0.8 {mu}mol L{sup -1} to 100 {mu}mol L{sup -1}. The analytical frequency can attain 300 determinations per hour and the detection limit was estimated in 0.34 {mu}mol L{sup -1} (3{sigma}). The anodic current peaks obtained after a series of 23 successive injections of 50 {mu}L of 25 {mu}mol L{sup -1} H{sub 2}O{sub 2} showed an RSD < 0.9%. To ensure the good selectivity to detect H{sub 2}O{sub 2}, its determination was performed in a differential mode, with selective destruction of the H{sub 2}O{sub 2} with catalase in 10 mmol L{sup -1} phosphate buffer solution. Practical application of the analytical procedure involved H{sub 2}O{sub 2} determination in rainwater of Sao Paulo City. A comparison of the results obtained by the proposed amperometric method with another one which

  8. Spectroscopic modeling and analysis of plasma conditions in implosion cores

    Science.gov (United States)

    Golovkin, Igor E.

    In this dissertation we discuss the effects of opacity and plasma gradients on the analysis and interpretation of Ar K-shell line emission from Ar-doped inertial confinement fusion (ICF) experiments, and introduce a spectroscopic technique for the determination of core plasma gradients. In particular, the Ar Heβ composite spectral feature is used for core plasma temperature and density diagnostics. We present a versatile, spectroscopic-quality Non-Local-Thermodynamic- Equilibrium radiation transport model that takes into account the effects of collisional-radiative atomic kinetics, plasma gradients, Stark-broadened line shapes and radiation transport. The code computes the radiative properties of the plasma, and it can be easily adapted to treat different problems of spectra formation. We discuss the importance of high-order satellite emission in the formation of Heβ spectral feature, and the interpretation of core averaged electron temperatures and densities extracted from space integrated spectra of non- uniform plasmas. We also present an application of Genetic Algorithms to the analysis of experimental X-ray spectra. This algorithm drives the search for plasma parameters that yield the best fits to experimental spectra. We discuss the applicability of Case Injected Genetic Algorithms to accelerate analysis of spectra. Furthermore, we introduce a novel method for the determination of plasma temperature and density gradients in imploded cores. The gradients are extracted from the self-consistent analysis of time-resolved X-ray spectra and spatial emissivity distributions obtained from X-ray monochromatic images. In this case, the search in the complex parameter space of gradient functions is driven by a multi-objective Niched Pareto Genetic Algorithm. We discuss the analysis of time resolved spectra recorded during Ar-doped ICF implosions at the NOVA laser facility. Time histories of core averaged electron densities and temperatures during the collapse of the

  9. Effects of real viscosity on plasma liner formation and implosion from supersonic plasma jets

    Science.gov (United States)

    Schillo, Kevin; Cassibry, Jason; Hsu, Scott; PLX-Alpha Team

    2015-11-01

    The PLX- α project endeavors to study plasma liner formation and implosion by merging of a spherical array of plasma jets as a candidate standoff driver for magneto-inertial fusion (MIF). Smoothed particle hydrodynamics (SPH) is being used to model the liner formation and implosion processes. SPH is a meshless Lagrangian method to simulate fluid flows by dividing a fluid into a set of particles and using a summation interpolant function to calculate the properties and gradients for each of these particles. The SPH code was used to simulate test cases in which the number of plasma guns and initial conditions for the plasma were varied. Linear stabilizations were observed, but the possibility exists that this stabilization was due to the implementation of artificial viscosity in the code. A real viscosity model was added to our SPHC model using the Braginskii ion viscosity. Preliminary results for test cases that incorporate real viscosity are presented.

  10. Expectations for the Laguna foil implosion experiments

    International Nuclear Information System (INIS)

    Building on the results achieved in the Pioneer shot series, the Los Alamos Trailmaster project is embarking on the Laguna foil implosion experiments. In this series a Mark-IX helical generator will be coupled to an explosively formed fuse opening switch, a surface-tracking closing switch, and a vacuum power flow and load chamber. In this paper the system design will be discussed and results from zero-, one-, and two-dimensional MHD simulations will be presented. It is anticipated that the generator will provide more than 10 MA of which ∼5.5 MA will be switched to the 5-cm-radius, 2-cm-high, 250-nm-thick aluminum foil load. This should give rise to a 1 μs implosion with more than 100 kJ of kinetic energy

  11. Contribution to the understanding of the high magnetic field compression produced by the implosion of a thin metal tube

    International Nuclear Information System (INIS)

    In this report we present the essential phenomena which occur during the magnetic flux compression obtained by the explosive-driven implosion of a thin conducting liner: acceleration time, dynamic evolution, heating and instability behaviour of the liner; field diffusion through the conducting wall and resulting flux losses which condition the increasing field in the cavity. Various implosion models are proposed and the one most elaborated leads to a numerical computation of the flux compression. Repeated experiments have permitted us to define and improve the flux injection techniques, the optical and electrical diagnostics and, consequently, the final compressed field. We now know how to obtain and record reproducible fields of 12 MOe in 0.8 cm diameter cavities. The final phase or the liner 'turnaround' has been specially observed. All the implosion shots are compared to the theoretical expectation. It may be concluded that the liner electrical conductivity and its variation essentially determine the final flux value. (author)

  12. Kinetic studies of ICF implosions

    Science.gov (United States)

    Kagan, Grigory; Herrmann, H. W.; Kim, Y.-H.; Schmitt, M. J.; Hakel, P.; Hsu, S. C.; Hoffman, N. M.; Svyatsky, D.; Baalrud, S. D.; Daligault, J. O.; Sio, H.; Zylstra, A. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Frenje, J. A.; Séguin, F. H.; Li, C. K.; Petrasso, R. D.; Albright, B. J.; Taitano, W.; Kyrala, G. A.; Bradley, P. A.; Huang, C.-K.; McDevitt, C. J.; Chacon, L.; Srinivasan, B.; McEvoy, A. M.; Joshi, T. R.; Adams, C. S.

    2016-05-01

    Kinetic effects on inertial confinement fusion have been investigated. In particular, inter-ion-species diffusion and suprathermal ion distribution have been analyzed. The former drives separation of the fuel constituents in the hot reacting core and governs mix at the shell/fuel interface. The latter underlie measurements obtained with nuclear diagnostics, including the fusion yield and inferred ion burn temperatures. Basic mechanisms behind and practical consequences from these effects are discussed.

  13. Radiation Driven Implosion and Triggered Star Formation

    CERN Document Server

    Bisbas, T G; Wünsch, R; Hubber, D A; Walch, S

    2010-01-01

    We present simulations of initially stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to radiatively driven implosion and star formation. We use the Smoothed Particle Hydrodynamics code SEREN (Hubber et al. 2010) and the HEALPix-based photoionization algorithm described in Bisbas et al. (2009). We find that the incident ionizing flux is the critical parameter determining the evolution: high fluxes simply disperse the cloud, whereas low fluxes trigger star formation. We find a clear connection between the intensity of the incident flux and the parameters of star formation.

  14. Wave dynamics of theta pinch implosions

    International Nuclear Information System (INIS)

    A model based on two constraints is proposed for theta pinch implosions. The first constraint states that the external radial force per mass density is the same for both electron and ion fluids like in a newtonian system. The second constraint is the quasi-neutrality. In cylindrical geometry, this model claims different radial velocities for the two fluids, plasma rotation in the azimuthal direction, and a minimum two dimensional consistent description. The physics of electron beam current saturation is shown to be very relevant in reverse biased pinches. (author)

  15. Explosion, implosion, and moments of passage times for continuous-time Markov chains: a semimartingale approach

    CERN Document Server

    Menshikov, Mikhail

    2012-01-01

    We establish general theorems quantifying the notion of recurrence --- through an estimation of the moments of passage times --- for irreducible continuous-time Markov chains on countably infinite state spaces. Sharp conditions of occurrence of the phenomenon of explosion are also obtained. A new phenomenon of implosion is introduced and sharp conditions for its occurrence are proven. The general results are illustrated by treating models having a difficult behaviour even in discrete time.

  16. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    Science.gov (United States)

    Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

    2016-11-01

    TiO2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals' precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Agcore-Cushell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  17. Planar wire array performance scaling at multi-MA levels on the Saturn generator.

    Energy Technology Data Exchange (ETDEWEB)

    Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, Michael; Vesey, Roger Alan; Waisman, Eduardo M.; Esaulov, Andrey A. (University of Nevada, Reno, NV); Ampleford, David J.; Kantsyrev, Victor Leonidovich (University of Nevada, Reno, NV); Cuneo, Michael Edward; Rudakov, L. I. (Icarus Research Inc., Bethesda, MD); Coverdale, Christine Anne; Jones, Brent Manley; Safronova, Alla S. (University of Nevada, Reno, NV)

    2007-10-01

    A series of twelve shots were performed on the Saturn generator in order to conduct an initial evaluation of the planar wire array z-pinch concept at multi-MA current levels. Planar wire arrays, in which all wires lie in a single plane, could offer advantages over standard cylindrical wire arrays for driving hohlraums for inertial confinement fusion studies as the surface area of the electrodes in the load region (which serve as hohlraum walls) may be substantially reduced. In these experiments, mass and array width scans were performed using tungsten wires. A maximum total radiated x-ray power of 10 {+-} 2 TW was observed with 20 mm wide arrays imploding in {approx}100 ns at a load current of {approx}3 MA, limited by the high inductance. Decreased power in the 4-6 TW range was observed at the smallest width studied (8 mm). 10 kJ of Al K-shell x-rays were obtained in one Al planar array fielded. This report will discuss the zero-dimensional calculations used to design the loads, the results of the experiments, and potential future research to determine if planar wire arrays will continue to scale favorably at current levels typical of the Z machine. Implosion dynamics will be discussed, including x-ray self-emission imaging used to infer the velocity of the implosion front and the potential role of trailing mass. Resistive heating has been previously cited as the cause for enhanced yields observed in excess of jxB-coupled energy. The analysis presented in this report suggests that jxB-coupled energy may explain as much as the energy in the first x-ray pulse but not the total yield, which is similar to our present understanding of cylindrical wire array behavior.

  18. Strong shock implosion, approximate solution

    Science.gov (United States)

    Fujimoto, Y.; Mishkin, E. A.; Alejaldre, C.

    1983-01-01

    The self-similar, center-bound motion of a strong spherical, or cylindrical, shock wave moving through an ideal gas with a constant, γ= cp/ cv, is considered and a linearized, approximate solution is derived. An X, Y phase plane of the self-similar solution is defined and the representative curved of the system behind the shock front is replaced by a straight line connecting the mappings of the shock front with that of its tail. The reduced pressure P(ξ), density R(ξ) and velocity U1(ξ) are found in closed, quite accurate, form. Comparison with numerically obtained results, for γ= {5}/{3} and γ= {7}/{5}, is shown.

  19. Modelling the effect of 3He in direct drive capsule implosions

    Science.gov (United States)

    Garbett, W. J.; Horsfield, C. J.; Herrmann, H. W.; Langenbrunner, J. R.; Cooley, J. H.; Wilson, D. C.; Evans, S. C.; Sedillo, T. J.; Rubery, M. S.; Drew, D.; Mack, J. M.; Young, C. S.; Kyrala, G. A.; Frenje, J.; Glebov, V. Yu

    2010-08-01

    D3He fuels are often used in ICF implosion experiments, either as a surrogate for DT to restrict the output neutron yield, or to produce protons for use in diagnosis of core conditions. Recent experiments have suggested that capsules filled with D3He do not behave as expected, but that both proton and neutron yields are anomalously degraded relative to the pure D2 case. We have performed direct drive implosion experiments using the Omega laser to examine the effect of 3He on DT-filled glass capsules. The use of DT fuel allows reaction history measurements to be obtained using the Gas Cherenkov diagnostic (GCD). It was hoped that the detailed information provided by GCD measurements would complement existing measurements to constrain modelling. We present recent modelling and analysis of the experiments using radiation-hydrocode simulations, and explore some of the hypotheses proposed to explain the results.

  20. On the analysis of shock implosion

    Science.gov (United States)

    Mishkin, Eli A.; Alejaldre, Carlos

    1984-06-01

    An imploding shock wave, coming from infinity, moves through an ideal gas with the adiabatic constant γ. To define a single-valued self-similar coefficient λ(γ), over the whole classical interval 1 < γ < ∞, its boundary values λ(1), λ(∞) are deduced. The conservation equations, cast in form of quadratics, exhibit their singular points P,M,M‧. At P the pressure is maximum, at M the velocity of the gas U1, minus ξ, equals the speed of sound C, at M‧ there is a linear relationship between U1, U˙1 and C. The representative curve of the compressed gas passes analytically through all of them. The relative position of P, M, M‧ leads to three solutions of the quadratic conservation equations. Representative curves of the state of the imploded gas, at various values of γ, are shown. The errors associated with the idealized models of implosion and explosion are evaluated.

  1. Laser fusion implosion and plasma interaction experiments

    Energy Technology Data Exchange (ETDEWEB)

    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/sup 9/ neutrons per event. It is shown how this data can be normalized with a simple scaling law.

  2. Ion-induced quark-gluon implosion.

    Science.gov (United States)

    Frankfurt, L; Strikman, M

    2003-07-11

    We investigate nuclear fragmentation in the central proton-nucleus and nucleus-nucleus collisions at the energies of CERN LHC. Within the semiclassical approximation we argue that because of the fast increase with energy of the cross sections of soft and hard interactions each nucleon is stripped in the average process off "soft" partons and fragments into a collection of leading quarks and gluons with large p(t). Valence quarks and gluons are streaming in the opposite directions when viewed in the c.m. of the produced system. The resulting pattern of the fragmentation of the colliding nuclei leads to an implosion of the quark and gluon constituents of the nuclei. The nonequilibrium state produced at the initial stage in the nucleus fragmentation region is estimated to have densities >/=50 GeV/fm(3) at the LHC energies and probably >/=10 GeV/fm(3) at BNL RHIC. PMID:12906475

  3. The effect of laser spot shapes on polar-direct-drive implosions on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Weilacher, F. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA; Radha, P. B. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA; Collins, T. J. B. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA; Marozas, J. A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA

    2015-03-01

    Ongoing polar-direct-drive (PDD) implosions on the National Ignition Facility (NIF) [J. D. Lindl and E. I. Moses, Phys. Plasmas 18, 050901 (2011)] use existing NIF hardware, including indirect-drive phase plates. This limits the performance achievable in these implosions. Spot shapes are identified that significantly improve the uniformity of PDD NIF implosions; outer surface deviation is reduced by a factor of 7 at the end of the laser pulse and hot-spot distortion is reduced by a factor of 2 when the shell has converged by a factor of 10. As a result, the neutron yield increases by approximately a factor of 2. This set of laser spot shapes is a combination of circular and elliptical spots, along with elliptical spot shapes modulated by an additional higher-intensity ellipse offset from the center of the beam. This combination is motivated in this paper. It is also found that this improved implosion uniformity is obtained independent of the heat conduction model. This work indicates that significant improvement in performance can be obtained robustly with the proposed spot shapes.

  4. The effect of laser spot shapes on polar-direct-drive implosions on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Weilacher, F.; Radha, P. B., E-mail: rbah@lle.rochester.edu; Collins, T. J. B.; Marozas, J. A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2015-03-15

    Ongoing polar-direct-drive (PDD) implosions on the National Ignition Facility (NIF) [J. D. Lindl and E. I. Moses, Phys. Plasmas 18, 050901 (2011)] use existing NIF hardware, including indirect-drive phase plates. This limits the performance achievable in these implosions. Spot shapes are identified that significantly improve the uniformity of PDD NIF implosions; outer surface deviation is reduced by a factor of 7 at the end of the laser pulse and hot-spot distortion is reduced by a factor of 2 when the shell has converged by a factor of ∼10. As a result, the neutron yield increases by approximately a factor of 2. This set of laser spot shapes is a combination of circular and elliptical spots, along with elliptical spot shapes modulated by an additional higher-intensity ellipse offset from the center of the beam. This combination is motivated in this paper. It is also found that this improved implosion uniformity is obtained independent of the heat conduction model. This work indicates that significant improvement in performance can be obtained robustly with the proposed spot shapes.

  5. Crossed-beam energy transfer in direct-drive implosions

    Energy Technology Data Exchange (ETDEWEB)

    Seka, W; Edgell, D H; Michel, D T; Froula, D H; Goncharov, V N; Craxton, R S; Divol, L; Epstein, R; Follett, R; Kelly, J H; Kosc, T Z; Maximov, A V; McCrory, R L; Meyerhofer, D D; Michel, P; Myatt, J F; Sangster, T C; Shvydky, A; Skupsky, S

    2012-05-22

    Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of the scattered (non-absorbed) light levels and measured ones that indicate the presence of a mechanism that reduces laser coupling efficiency by 10%-20%. This appears to be due to crossed-beam energy transfer (CBET) that involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters energy from the central portion of the incoming light beam to outgoing light, reducing the laser absorption and hydrodynamic efficiency of implosions. One-dimensional hydrodynamic simulations including CBET show good agreement with all observables in implosion experiments on OMEGA. Three strategies to mitigate CBET and improve laser coupling are considered: the use of narrow beams, multicolor lasers, and higher-Z ablators. Experiments on OMEGA using narrow beams have demonstrated improvements in implosion performance.

  6. Implosion of an underwater spark-generated bubble and acoustic energy evaluation using the Rayleigh model.

    Science.gov (United States)

    Buogo, Silvano; Cannelli, Giovanni B

    2002-06-01

    The growth, collapse, and rebound of a vapor bubble generated by an underwater spark is studied by means of high-speed cinematography, simultaneously acquiring the emitted acoustic signature. Video recordings show that the growth and collapse phases are nearly symmetrical during the first two or three cycles, the bubble shape being approximately spherical. After 2-3 cycles the bubble behavior changes from a collapsing/rebounding regime with sound-emitting implosions to a pulsating regime with no implosions. The motion of the bubble wall during the first collapses was found to be consistent with the Rayleigh model of a cavity in an incompressible liquid, with the inclusion of a vapor pressure term at constant temperature within each bubble cycle. An estimate of the pressure inside the bubble is obtained measuring the collapse time and maximum radius, and the amount of energy converted into acoustical energy upon each implosion is deduced. The resulting value of acoustic efficiency was found to be in agreement with measurements based on the emitted acoustic pulse.

  7. QUICK-FIRE: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion

  8. Quick-fire: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion. Experiments have been conducted using the SHIVA STAR capacitor bank operating at 6 MJ stored energy in which performance has been monitored by electrical diagnostics, magnetic probes, and axial and radial viewing high speed visible and X-Ray photographs to assess the performance of the coaxial run and coaxial to radial transition. Time and spectrally resolved X-Ray diagnostics are used to assess implosion quality and performance and results are compared to kinematic and MHD models

  9. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong, E-mail: amosrxd@163.com; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun [Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-108, Mianyang, Sichuan 621999 (China); Zhou, Xiu-Wen; Yang, Yi [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-987, Mianyang, Sichuan 621999 (China)

    2015-07-15

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

  10. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    International Nuclear Information System (INIS)

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed

  11. Two-frame flash x-radiography system for target implosion studies

    International Nuclear Information System (INIS)

    A two-frame flash x-radiography system has been developed to study target implosion dynamics. It is capable of taking two time separated 3 ns exposure x-ray shadowgrams of a particle beam driven target implosion

  12. Indirectly driven, high-convergence implosions (HEP1)

    Energy Technology Data Exchange (ETDEWEB)

    Hatchett, S.P.; Cable, M.D.; Caird, J.A. [and others

    1996-06-01

    High-gain inertial confinement fusion will most readily be achieved with hot-spot ignition, in which a relatively small mass of gaseous fuel at the center of the target is heated to 5-10 keV, igniting a larger surrounding mass of approximately isobaric fuel at higher density but lower temperature. Existing lasers are too low in energy to achieve thermonuclear gain, but hydrodynamically equivalent implosions using these lasers can demonstrate that the important, scalable parameters of ignition capsules are scientifically and technologically achievable. The experiments described in this article used gas-filled glass shells driven by x rays produced in a surrounding cavity, or hohlraum. These implosions achieved convergence ratios (initial capsule radius/ final fuel radius) high enough to fall in the range required for ignition-scale capsules, and they produced an imploded configuration (high-density glass with hot gas fill) that is equivalent to the hot-spot configuration of an ignition-scale capsule. Other recent laser-driven implosions have achieved high shell density but at lower convergences and without a well defined hot spot. Still other experiments have used very-low-density gas fill to reach high convergence with unshaped drive, but that approach results in a relatively low shell density. Moreover, even at the highest convergence ratios the implosions described here had neutron yields averaging 8% of that calculated for an idealized, clean, spherically symmetric implosion - much higher than previous high-convergence experiments.

  13. Uniformity of fuel target implosion in Heavy Ion Fusion

    CERN Document Server

    Kawata, S; Suzuki, T; Karino, T; Barada, D; Ogoyski, A I; Ma, Y Y

    2015-01-01

    In inertial confinement fusion the target implosion non-uniformity is introduced by a driver beams' illumination non-uniformity, a fuel target alignment error in a fusion reactor, the target fabrication defect, et al. For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the requirement for the implosion uniformity is first discussed. The implosion uniformity should be less than a few percent. A study on the fuel hotspot dynamics is also presented and shows that the stagnating plasma fluid provides a significant enhancement of vorticity at the final stage of the fuel stagnation. Then non-uniformity mitigation mechanisms of the heavy ion beam (HIB) illumination are also briefly discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to a radiation energy smoothing. In HIF a wobbling he...

  14. Progress of LMJ-relevant implosions experiments on OMEGA

    Directory of Open Access Journals (Sweden)

    Casner A.

    2013-11-01

    Full Text Available In preparation of the first ignition attempts on the Laser Mégajoule (LMJ, an experimental program is being pursued on OMEGA to investigate LMJ-relevant hohlraums. First, radiation temperature levels close to 300 eV were recently achieved in reduced-scale hohlraums with modest backscatter losses. Regarding the baseline target design for fusion experiments on LMJ, an extensive experimental database has also been collected for scaled implosions experiments in both empty and gas-filled rugby-shaped hohlraums. We acquired a full picture of hohlraum energetics and implosion dynamics. Not only did the rugby hohlraums show significantly higher x-ray drive energy over the cylindrical hohlraums, but symmetry control by power balance was demonstrated, as well as high-performance D2 implosions enabling the use of a complete suite of neutrons diagnostics. Charged particle diagnostics provide complementary insights into the physics of these x-ray driven implosions. An overview of these results demonstrates our ability to control the key parameters driving the implosion, lending more confidence in extrapolations to ignition-scale targets.

  15. Asymmetry influence on indirect-drive Iskra-5 implosions

    Energy Technology Data Exchange (ETDEWEB)

    Mkhitarian, L.S.; Bel' kov, S.A.; Bassarab, A.V.; Bondarenko, S.V.; Eremenko, Y.N.; Vinokurov, O.A.; Gaidash, V.A.; Zhidkov, N.V.; Isgorodin, V.M.; Kirillov, G.A.; Kochemasov, G.G.; Litvin, D.N.; Martinenko, S.P.; Murugov, V.M.; Petrov, S.I.; Pinegin, A.V.; Suslov, N.A. [Russian Federal Nuclear Center, VNIIEF, Sarov (Russian Federation)

    2000-07-01

    A high and stable symmetry of X-ray drive inside a spherical hohlraum (with the ratio of hohlraum and capsule diameters about 7) allowed us to investigate the influence of a controlled large scale asymmetry of a capsule with DT-fuel on target implosion performance. By varying the thickness of asymmetric coating of the target shell we could change the neutron yield, time separation between X-ray and neutron pulses and other parameters of implosion. By varying thickness of the symmetric part of shell we could change the regime of implosion: from the exploding pusher regime to the ablative one. In new types of experiments we changed the X-ray drive asymmetry by shifting the capsule with DT out from the hohlraum (box) center towards the additional seventh hole in the box wall. (authors)

  16. Uniform fuel target implosion in heavy ion inertial fusion

    Science.gov (United States)

    Kawata, S.; Karino, T.; Kondo, S.; Iinuma, T.; Barada, D.; Ma, Y. Y.; Ogoyski, A. I.

    2016-05-01

    For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the non-uniformity mitigation mechanisms in the heavy ion beam (HIB) illumination are discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to the radiation energy smoothing for the HIB illumination non-uniformity. The large density-gradient scale, which is typically ∼500μm in HIF targets, also contributes to a reduction of the Rayleigh- Taylor instability growth rate. In HIF a wobbling HIBs illumination would also reduce the Rayleigh-Taylor instability growth and to realize a uniform implosion.

  17. First beryllium capsule implosions on the National Ignition Facility

    Science.gov (United States)

    Kline, J. L.; Yi, S. A.; Simakov, A. N.; Olson, R. E.; Wilson, D. C.; Kyrala, G. A.; Perry, T. S.; Batha, S. H.; Zylstra, A. B.; Dewald, E. L.; Tommasini, R.; Ralph, J. E.; Strozzi, D. J.; MacPhee, A. G.; Callahan, D. A.; Hinkel, D. E.; Hurricane, O. A.; Milovich, J. L.; Rygg, J. R.; Khan, S. F.; Haan, S. W.; Celliers, P. M.; Clark, D. S.; Hammel, B. A.; Kozioziemski, B.; Schneider, M. B.; Marinak, M. M.; Rinderknecht, H. G.; Robey, H. F.; Salmonson, J. D.; Patel, P. K.; Ma, T.; Edwards, M. J.; Stadermann, M.; Baxamusa, S.; Alford, C.; Wang, M.; Nikroo, A.; Rice, N.; Hoover, D.; Youngblood, K. P.; Xu, H.; Huang, H.; Sio, H.

    2016-05-01

    The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosion shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.

  18. Diagnosing radiative shocks from deuterium and tritium implosions on NIF.

    Science.gov (United States)

    Pak, A; Divol, L; Weber, S; Döppner, T; Kyrala, G A; Kilne, J; Izumi, N; Glenn, S; Ma, T; Town, R P; Bradley, D K; Glenzer, S H

    2012-10-01

    During the recent ignition tuning campaign at the National Ignition Facility, layered cryogenic deuterium and tritium capsules were imploded via x-ray driven ablation. The hardened gated x-ray imager diagnostic temporally and spatially resolves the x-ray emission from the core of the capsule implosion at energies above ~8 keV. On multiple implosions, ~200-400 ps after peak compression a spherically expanding radiative shock has been observed. This paper describes the methods used to characterize the radial profile and rate of expansion of the shock induced x-ray emission.

  19. Arcade Implosion Caused by a Filament Eruption in a Flare

    CERN Document Server

    Wang, Juntao; Fletcher, L; Thalmann, J K; Hudson, H S; Hannah, I G

    2016-01-01

    Coronal implosions - the convergence motion of plasmas and entrained magnetic field in the corona due to a reduction in magnetic pressure - can help to locate and track sites of magnetic energy release or redistribution during solar flares and eruptions. We report here on the analysis of a well-observed implosion in the form of an arcade contraction associated with a filament eruption, during the C3.5 flare SOL2013-06-19T07:29. A sequence of events including magnetic flux-rope instability and distortion, followed by filament eruption and arcade implosion, lead us to conclude that the implosion arises from the transfer of magnetic energy from beneath the arcade as part of the global magnetic instability, rather than due to local magnetic energy dissipation in the flare. The observed net contraction of the imploding loops, which is found also in nonlinear force-free field extrapolations, reflects a permanent reduction of magnetic energy underneath the arcade. This event shows that, in addition to resulting in e...

  20. Fuel gain exceeding unity in an inertially confined fusion implosion.

    Science.gov (United States)

    Hurricane, O A; Callahan, D A; Casey, D T; Celliers, P M; Cerjan, C; Dewald, E L; Dittrich, T R; Döppner, T; Hinkel, D E; Berzak Hopkins, L F; Kline, J L; Le Pape, S; Ma, T; MacPhee, A G; Milovich, J L; Pak, A; Park, H-S; Patel, P K; Remington, B A; Salmonson, J D; Springer, P T; Tommasini, R

    2014-02-20

    Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium-tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a 'high-foot' implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite.

  1. Implosion of the small cavity and large cavity cannonball targets

    International Nuclear Information System (INIS)

    Recent results of cannonball target implosion research are briefly reviewed with theoretical predictions for GEKKO XII experiments. The cannonball targets are classified into two types according to the cavity size ; small cavity and large cavity. The compression mechanisms of the two types are discussed. (author)

  2. Diagnosing implosion velocity and ablator dynamics at NIF (u)

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Anna [Los Alamos National Laboratory; Grim, Gary [Los Alamos National Laboratory; Jungnam, Jerry [Los Alamos National Laboratory; Bradley, Paul [Los Alamos National Laboratory; Rundberg, Bob [Los Alamos National Laboratory; Wilhelmy, Jerry [Los Alamos National Laboratory; Wilson, Doug [Los Alamos National Laboratory

    2009-07-09

    An enhanced understanding of the unique physics probed in a burning NIP capsule is important for both nuclear weapons physics and thermonuclear ignition. In this talk we introduce a new diagnostic idea, designed to measure dynamic aspects of the capsule implosion that are not currently accessible. The current set of diagnostics for the NIF experiments includes reaction history (a time resolved measure of the d + t burn), neutron time-of-flight and spectrometry and spatial imaging of the neutron production and scattering. Although valuable, this abbreviated set of diagnostics cannot determine key dynamical properties of the implosion, such as implosion velocity (v{sub impl}) and ablator thickness. To surpass the present limits of {approx} 10{sup 15} d+t reactions, it will be necessary to increase significantly the implosion energy delivered to the DT fuel by finely tuning the balance between the remaining (imploding) ablator mass and velocity. If too much mass remains, the implosion velocity will be too slow, and the subsecpwnt PdV work will not be sufficient to overcome cooling via conduction and radiation. If too little mass remains, hydrodynamic instabilities will occur, resulting in unpredictable and degraded performance. Detailed calculations suggest the ablator must reach an implosion velocity of 3-4 x 10{sup 7} cm/sec and an areal density of {rho}{Delta}R {approx}200 mg/cm{sup 2} in order to achieve ignition. The authors present a new scheme to measure these important quantities using neutron reactions on the ablator material. During the burn, the ablator is moving relative to the 14.1 MeV d+t neutrons that are traversing the capsule. The resulting neutron-ablator Doppler shift causes a few unique nuclear reactions to become sensitive detectors of the ablator velocity at peak burn time. The 'point-design' capsule at the NIF will be based on a {sup 9}Be ablator, and the {sup 9}Be(n,p){sup 9}Li reaction has an energy threshold of 14.2 MeV, making it

  3. 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.

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

    Science.gov (United States)

    Milovich, J. L.; 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.

    2015-12-01

    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/cm2, but with significantly lower total neutron yields (between 1.5 × 1014 and 5.5 × 1014) 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/cm2. 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.

  5. Plasma Viscosity with Mass Transport in Spherical ICF Implosion Simulations

    CERN Document Server

    Vold, Erik L; Ortega, Mario I; Moll, Ryan; Fenn, Daniel; Molvig, Kim

    2015-01-01

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrange hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduc...

  6. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    OpenAIRE

    Kawata S.; Kurosaki T.; Koseki S.; Hisatomi Y.; Barada D.; Ma Y.Y.; Ogoyski A.I.

    2013-01-01

    A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) throughout the heavy ion beam (HIB) driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the i...

  7. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    Directory of Open Access Journals (Sweden)

    Kawata S.

    2013-11-01

    Full Text Available A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF throughout the heavy ion beam (HIB driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T growth [Laser Part. Beams 11, 757 (1993, Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009, Phys. Plasmas 19, 024503 (2012] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

  8. A New Theory of Mix in Omega Capsule Implosions

    Science.gov (United States)

    Knoll, Dana; Chacon, Luis; Rauenzahn, Rick; Simakov, Andrei; Taitano, William; Welser-Sherrill, Leslie

    2014-10-01

    We put forth a new mix model that relies on the development of a charge-separation electrostatic double-layer at the fuel-pusher interface early in the implosion of an Omega plastic ablator capsule. The model predicts a sizable pusher mix (several atom %) into the fuel. The expected magnitude of the double-layer field is consistent with recent radial electric field measurements in Omega plastic ablator implosions. Our theory relies on two distinct physics mechanisms. First, and prior to shock breakout, the formation of a double layer at the fuel-pusher interface due to fast preheat-driven ionization. The double-layer electric field structure accelerates pusher ions fairly deep into the fuel. Second, after the double-layer mix has occurred, the inward-directed fuel velocity and temperature gradients behind the converging shock transports these pusher ions inward. We first discuss the foundations of this new mix theory. Next, we discuss our interpretation of the radial electric field measurements on Omega implosions. Then we discuss the second mechanism that is responsible for transporting the pusher material, already mixed via the double-layer deep into the fuel, on the shock convergence time scale. Finally we make a connection to recent mix motivated experimental data on. This work conducted under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory, managed by LANS, LLC under Contract DE-AC52-06NA25396.

  9. Influence and measurement of mass ablation in ICF implosions

    Energy Technology Data Exchange (ETDEWEB)

    Spears, B K; Hicks, D; Velsko, C; Stoyer, M; Robey, H; Munro, D; Haan, S; Landen, O; Nikroo, A; Huang, H

    2007-09-05

    Point design ignition capsules designed for the National Ignition Facility (NIF) currently use an x-ray-driven Be(Cu) ablator to compress the DT fuel. Ignition specifications require that the mass of unablated Be(Cu), called residual mass, be known to within 1% of the initial ablator mass when the fuel reaches peak velocity. The specifications also require that the implosion bang time, a surrogate measurement for implosion velocity, be known to +/- 50 ps RMS. These specifications guard against several capsule failure modes associated with low implosion velocity or low residual mass. Experiments designed to measure and to tune experimentally the amount of residual mass are being developed as part of the National Ignition Campaign (NIC). Tuning adjustments of the residual mass and peak velocity can be achieved using capsule and laser parameters. We currently plan to measure the residual mass using streaked radiographic imaging of surrogate tuning capsules. Alternative techniques to measure residual mass using activated Cu debris collection and proton spectrometry have also been developed. These developing techniques, together with bang time measurements, will allow us to tune ignition capsules to meet NIC specs.

  10. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    Science.gov (United States)

    Kawata, S.; Kurosaki, T.; Koseki, S.; Hisatomi, Y.; Barada, D.; Ma, Y. Y.; Ogoyski, A. I.

    2013-11-01

    A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) throughout the heavy ion beam (HIB) driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T) growth [Laser Part. Beams 11, 757 (1993), Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009), Phys. Plasmas 19, 024503 (2012)] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ˜ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010)]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

  11. The effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches

    Energy Technology Data Exchange (ETDEWEB)

    Li, M., E-mail: limo@nint.ac.cn; Li, Y. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China); State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Sheng, L.; Wang, L. P.; Zhao, C.; Yuan, Y.; Zhang, X. J.; Zhang, M.; Peng, B. D.; Zhang, J. H.; Zhang, S. G.; Qiu, M. T. [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Li, X. W. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China)

    2015-12-15

    This paper presents experimental results on the effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches on ∼100 ns main current facility. Optical framing images indicated that without a current prepulse the wire ablation process was asymmetrical and the implosion was zippered. The x-ray peak power was ∼320 GW. By using insulating coatings on the wire surface the asymmetry remained, and the processes of ablation and implosion were delayed by ∼30 ns. The x-ray burst was narrow and decreased to ∼200 GW. When current prepulses were used on both standard and insulated wire arrays, implosion symmetry was improved and the x-ray burst was improved (to ∼520 GW peak power). In addition, there was a strong emitting precursor column for insulated loads with the current prepulse.

  12. Recent advances in theoretical and numerical studies of wire array Z-pinch in the IAPCM

    Science.gov (United States)

    Ding, Ning; Zhang, Yang; Xiao, Delong; Wu, Jiming; Huang, Jun; Yin, Li; Sun, Shunkai; Xue, Chuang; Dai, Zihuan; Ning, Cheng; Shu, Xiaojian; Wang, Jianguo; Li, Hua

    2014-12-01

    Fast Z-pinch has produced the most powerful X-ray radiation source in laboratory and also shows the possibility to drive inertial confinement fusion (ICF). Recent advances in wire-array Z-pinch researches at the Institute of Applied Physics and Computational Mathematics are presented in this paper. A typical wire array Z-pinch process has three phases: wire plasma formation and ablation, implosion and the MRT instability development, stagnation and radiation. A mass injection model with azimuthal modulation coefficient is used to describe the wire initiation, and the dynamics of ablated plasmas of wire-array Z-pinches in (r, θ) geometry is numerically studied. In the implosion phase, a two-dimensional(r, z) three temperature radiation MHD code MARED has been developed to investigate the development of the Magneto-Rayleigh-Taylor(MRT) instability. We also analyze the implosion modes of nested wire-array and find that the inner wire-array is hardly affected before the impaction of the outer wire-array. While the plasma accelerated to high speed in the implosion stage stagnates on the axis, abundant x-ray radiation is produced. The energy spectrum of the radiation and the production mechanism are investigated. The computational x-ray pulse shows a reasonable agreement with the experimental result. We also suggest that using alloyed wire-arrays can increase multi-keV K-shell yield by decreasing the opacity of K-shell lines. In addition, we use a detailed circuit model to study the energy coupling between the generator and the Z-pinch implosion. Recently, we are concentrating on the problems of Z-pinch driven ICF, such as dynamic hohlraum and capsule implosions. Our numerical investigations on the interaction of wire-array Z-pinches on foam convertors show qualitative agreements with experimental results on the "Qiangguang I" facility. An integrated two-dimensional simulation of dynamic hohlraum driven capsule implosion provides us the physical insights of wire-array

  13. Wavelength scaling of implosion symmetry, ablation pressure, and hydrodynamic efficiency in laser fusion

    International Nuclear Information System (INIS)

    We examine the scaling of implosion symmetry, ablation pressure, and hydrodynamic efficiency with the wavelength of the laser, using a recent theoretical analysis of ablative laser driven implosions as a tool. Symmetrization by a hot atmosphere is most effective for long wavelength lasers, whereas ablation pressure and hydrodynamic efficiency are best for shorter laser wavelengths

  14. In-flight observations of low-mode ρR asymmetries in NIF implosions

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Rygg, J. R.; Kritcher, A.; Hicks, D. G.; Friedrich, S.; Bionta, R.; Meezan, N. B.; Atherton, J.; Barrios, M.; Bell, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2015-05-15

    Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale indirect-drive implosions for the first time. Surrogate D{sup 3}He gas-filled implosions at the National Ignition Facility produce energetic protons via D+{sup 3}He fusion that are used to measure the implosion areal density (ρR) at the shock-bang time. By using protons produced several hundred ps before the main compression bang, the implosion is diagnosed in-flight at a convergence ratio of 3–5 just prior to peak velocity. This isolates acceleration-phase asymmetry growth. For many surrogate implosions, proton spectrometers placed at the north pole and equator reveal significant asymmetries with amplitudes routinely ≳10%, which are interpreted as ℓ=2 Legendre modes. With significant expected growth by stagnation, it is likely that these asymmetries would degrade the final implosion performance. X-ray self-emission images at stagnation show asymmetries that are positively correlated with the observed in-flight asymmetries and comparable in magnitude, contradicting growth models; this suggests that the hot-spot shape does not reflect the stagnated shell shape or that significant residual kinetic energy exists at stagnation. More prolate implosions are observed when the laser drive is sustained (“no-coast”), implying a significant time-dependent asymmetry in peak drive.

  15. Evaluation of the Biofire FilmArray BioThreat-E Test (v2.5) for Rapid Identification of Ebola Virus Disease in Heat-Treated Blood Samples Obtained in Sierra Leone and the United Kingdom.

    Science.gov (United States)

    Weller, Simon A; Bailey, Daniel; Matthews, Steven; Lumley, Sarah; Sweed, Angela; Ready, Derren; Eltringham, Gary; Richards, Jade; Vipond, Richard; Lukaszewski, Roman; Payne, Phillippa M; Aarons, Emma; Simpson, Andrew J; Hutley, Emma J; Brooks, Tim

    2016-01-01

    Rapid Ebola virus (EBOV) detection is crucial for appropriate patient management and care. The performance of the FilmArray BioThreat-E test (v2.5) using whole-blood samples was evaluated in Sierra Leone and the United Kingdom and was compared with results generated by a real-time Ebola Zaire PCR reference method. Samples were tested in diagnostic laboratories upon availability, included successive samples from individual patients, and were heat treated to facilitate EBOV inactivation prior to PCR. The BioThreat-E test had a sensitivity of 84% (confidence interval [CI], 64% to 95%) and a specificity of 89% (CI, 73% to 97%) in Sierra Leone (n = 60; 44 patients) and a sensitivity of 75% (CI, 19% to 99%) and a specificity of 100% (CI, 97% to 100%) in the United Kingdom (n = 108; 70 patients) compared to the reference real-time PCR. Statistical analysis (Fisher's exact test) indicated there was no significant difference between the methods at the 99% confidence level in either country. In 9 discrepant results (5 real-time PCR positives and BioThreat-E test negatives and 4 real-time PCR negatives and BioThreat-E test positives), the majority (n = 8) were obtained from samples with an observed or probable low viral load. The FilmArray BioThreat-E test (v2.5) therefore provides an attractive option for laboratories (either in austere field settings or in countries with an advanced technological infrastructure) which do not routinely offer an EBOV diagnostic capability.

  16. Control of fuel target implosion non-uniformity in heavy ion inertial fusion

    CERN Document Server

    Iinuma, T; Kondo, S; Kubo, T; Kato, H; Suzuki, T; Kawata, S; Ogoyski, A I

    2016-01-01

    In inertial fusion, one of scientific issues is to reduce an implosion non-uniformity of a spherical fuel target. The implosion non-uniformity is caused by several factors, including the driver beam illumination non-uniformity, the Rayleigh-Taylor instability (RTI) growth, etc. In this paper we propose a new control method to reduce the implosion non-uniformity; the oscillating implosion acceleration dg(t) is created by pulsating and dephasing heavy ion beams (HIBs) in heavy ion inertial fusion (HIF). The dg(t) would reduce the RTI growth effectively. The original concept of the non- uniformity control in inertial fusion was proposed in (Kawata, et al., 1993). In this paper it was found that the pulsating and dephasing HIBs illumination provide successfully the controlled dg(t) and that dg(t) induced by the pulsating HIBs reduces well the implosion non-uniformity. Consequently the pulsating HIBs improve a pellet gain remarkably in HIF.

  17. ''QUICK-FIRE'' plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    The QUICK-FIRE experimental series presently being conducted on the SHIVA STAR fast capacitor bank (120 KV, 9.3 MJ) at the Air Force Weapons Laboratory is described. Diagnostics used to measure physical quantities are listed and preliminary results from the first eight shots are presented. Initial data indicates that the performance of the coaxial gun portion of the plasma flow switch is good. Radiation yields from the unoptimized implosions are 220 KJ of soft x-rays in the 80-280 eV range with a peak power of roughly 1.25 TW. Plans for future work are outlined

  18. Understanding the stagnation and burn of implosions on NIF

    Science.gov (United States)

    Kilkenny, J. D.; Caggiano, J. A.; Hatarik, R.; Knauer, J. P.; Sayre, D. B.; Spears, B. K.; Weber, S. V.; Yeamans, C. B.; Cerjan, C. J.; Divol, L.; Eckart, M. J.; Glebov, V. Yu; Herrmann, H. W.; Le Pape, S.; Munro, D. H.; Grim, G. P.; Jones, O. S.; Berzak-Hopkins, L.; Gatu-Johnson, M.; Mackinnon, A. J.; Meezan, N. B.; Casey, D. T.; Frenje, J. A.; Mcnaney, J. M.; Petrasso, R.; Rinderknecht, H.; Stoeffl, W.; Zylstra, A. B.

    2016-03-01

    An improved the set of nuclear diagnostics on NIF measures the properties of the stagnation plasma of implosions, including the drift velocity, areal density (ρr) anisotropy and carbon ρr of the compressed core. Two types of deuterium-tritium (DT) gas filled targets are imploded by shaped x-ray pulses, producing stagnated and burning DT cores of radial convergence (Cr) ∼ 5 or ∼20. Comparison with two-dimensional modeling with inner and outer surface mix shows good agreement with nuclear measurements.

  19. EFFECT BY RADIATIVE ENERGY TRANSPORT IN PUSHER LAYER AND TRANSPORT PROPERTY OF FUEL ON NONUNIFORM IMPLOSION OF TARGET IRRADIATED BY ION BEAM

    OpenAIRE

    Niu, K.; Aoki, T.

    1988-01-01

    In order to obtain a high pressure to compress DT fuel in target for ICF, momenta of pusher and fuel itself are converted to impulse. Compressibility of fuel depends strongly on its equation of state. Target is usually not illuminated by energy driver in spherically symmetric way. Nonuniform implosion decreases severely the rate of fuel compression. Radiative energy transport in pusher layer homogenizes profile of nonuniform pressure which is originated by a nonuniform deposition of driver en...

  20. Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF.

    Science.gov (United States)

    Döppner, T; Dewald, E L; Divol, L; Thomas, C A; Burns, S; Celliers, P M; Izumi, N; Kline, J L; LaCaille, G; McNaney, J M; Prasad, R R; Robey, H F; Glenzer, S H; Landen, O L

    2012-10-01

    We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.

  1. Diagnosing Implosion Velocity and Ablator Dynamics at NIF

    Science.gov (United States)

    Grim, Gary; Hayes, Anna; Jungman, Jerry; Wilson, Doug; Wilhelmy, Jerry; Bradley, Paul; Rundberg, Bob; Cerjan, Charlie

    2009-10-01

    An enhanced understanding of the environment in a burning NIF capsule is of interest to both astrophysics and thermonuclear ignition. In this talk we introduce a new diagnostic idea, designed to measure dynamic aspects of the capsule implosion that are not currently accessible. During the burn,the NIF capsule ablator is moving relative to the 14.1 MeV dt neutrons that are traversing the capsule. The resulting neutron-ablator Doppler shift causes a few unique nuclear reactions to become sensitive detectors of the ablator velocity at peak burn time. The ``point-design'' capsule at the NIF will be based on a ^9Be ablator, and the ^9Be(n,p)^9Li reaction has an energy threshold of 14.2 MeV, making it the ideal probe. As discussed in detail below, differences in the ablator velocity lead to significant differences in the rate of ^9Li production. We present techniques for measuring this ^9Li implosion velocity diagnostic at the NIF. The same experimental techniques, measuring neutron reactions on the ablator material, will allow us to determine other important dynamical quantities, such as the areal density and approximate thickness of the ablator at peak burn.

  2. Modeling and diagnosing interface mix in layered ICF implosions

    Science.gov (United States)

    Weber, C. R.; Berzak Hopkins, L. F.; Clark, D. S.; Haan, S. W.; Ho, D. D.; Meezan, N. B.; Milovich, J. L.; Robey, H. F.; Smalyuk, V. A.; Thomas, C. A.

    2015-11-01

    Mixing at the fuel-ablator interface of an inertial confinement fusion (ICF) implosion can arise from an unfavorable in-flight Atwood number between the cryogenic DT fuel and the ablator. High-Z dopant is typically added to the ablator to control the Atwood number, but recent high-density carbon (HDC) capsules have been shot at the National Ignition Facility (NIF) without this added dopant. Highly resolved post-shot modeling of these implosions shows that there was significant mixing of ablator material into the dense DT fuel. This mix lowers the fuel density and results in less overall compression, helping to explain the measured ratio of down scattered-to-primary neutrons. Future experimental designs will seek to improve this issue through adding dopant and changing the x-ray spectra with a different hohlraum wall material. To test these changes, we are designing an experimental platform to look at the growth of this mixing layer. This technique uses side-on radiography to measure the spatial extent of an embedded high-Z tracer layer near the interface. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  3. Implosion Robustness, Time-Dependent Flux Asymmetries and Big Data

    Science.gov (United States)

    Peterson, J. L.; Field, J. E.; Spears, B. K.; Brandon, S. T.; Gaffney, J. A.; Hammer, J.; Kritcher, A.; Nora, R. C.; Springer, P. T.

    2015-11-01

    Both direct and indirect drive inertial confinement fusion rely on the formation of spherical implosions, which can be a challenge under temporal and spatial drive variations (either from discrete laser beams, a complex hohlraum radiation environment, or both). To that end, we examine the use of large simulation databases of 2D capsule implosions to determine the sensitivity of indirectly driven NIF designs to time-varying low-mode radiation drive asymmetries at varying convergence ratios. In particular, we define and calculate a large number of extensive quantities for the simulations within the database and compare with the equivalent quantities extracted from fully 3D simulations and those used in 1D hydrodynamic models. Additionally, we discuss some of the practical challenges of searching for physical insight in multi-petabyte datasets. This work 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-674884.

  4. A technique for extending by ∼103 the dynamic range of compact proton spectrometers for diagnosing ICF implosions on the National Ignition Facility and OMEGA

    International Nuclear Information System (INIS)

    Wedge Range Filter (WRF) proton spectrometers are routinely used on OMEGA and the NIF for diagnosing ρR and ρR asymmetries in direct- and indirect-drive implosions of D3He-, D2-, and DT-gas-filled capsules. By measuring the optical opacity distribution in CR-39 due to proton tracks in high-yield applications, as opposed to counting individual tracks, WRF dynamic range can be extended by 102 for obtaining the spectral shape, and by 103 for mean energy (ρR) measurement, corresponding to proton fluences of 108 and 109 cm−2, respectively. Using this new technique, ρR asymmetries can be measured during both shock and compression burn (proton yield ∼108 and ∼1012, respectively) in 2-shock National Ignition Facility implosions with the standard WRF accuracy of ±∼10 mg/cm2

  5. Probing off-Hugoniot states in Ta, Cu, and Al to 1000 GPa compression with magnetically driven liner implosions

    Energy Technology Data Exchange (ETDEWEB)

    Lemke, R. W., E-mail: rwlemke@sandia.gov; Dolan, D. H.; Dalton, D. G.; Brown, J. L.; Robertson, G. R.; Harding, E.; Mattsson, A. E.; Carpenter, J. H.; Drake, R. R.; Cochrane, K.; Robinson, A. C.; Mattsson, T. R. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1189 (United States); Tomlinson, K.; Blue, B. E. [General Atomics, San Diego, California 92121 (United States); Knudson, M. D. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1189 (United States); Institute for Shock Physics and Department of Physics, Washington State University, Pullman, Washington 99164 (United States)

    2016-01-07

    We report on a new technique for obtaining off-Hugoniot pressure vs. density data for solid metals compressed to extreme pressure by a magnetically driven liner implosion on the Z-machine (Z) at Sandia National Laboratories. In our experiments, the liner comprises inner and outer metal tubes. The inner tube is composed of a sample material (e.g., Ta and Cu) whose compressed state is to be inferred. The outer tube is composed of Al and serves as the current carrying cathode. Another aluminum liner at much larger radius serves as the anode. A shaped current pulse quasi-isentropically compresses the sample as it implodes. The iterative method used to infer pressure vs. density requires two velocity measurements. Photonic Doppler velocimetry probes measure the implosion velocity of the free (inner) surface of the sample material and the explosion velocity of the anode free (outer) surface. These two velocities are used in conjunction with magnetohydrodynamic simulation and mathematical optimization to obtain the current driving the liner implosion, and to infer pressure and density in the sample through maximum compression. This new equation of state calibration technique is illustrated using a simulated experiment with a Cu sample. Monte Carlo uncertainty quantification of synthetic data establishes convergence criteria for experiments. Results are presented from experiments with Al/Ta, Al/Cu, and Al liners. Symmetric liner implosion with quasi-isentropic compression to peak pressure ∼1000 GPa is achieved in all cases. These experiments exhibit unexpectedly softer behavior above 200 GPa, which we conjecture is related to differences in the actual and modeled properties of aluminum.

  6. Charged-Particle Probing of X-ray-Driven Inertial-Fusion Implosions

    International Nuclear Information System (INIS)

    Measurements of x-ray-driven implosions with charged particles have resulted in the quantitative characterization of critical aspects of indirect-drive inertial fusion. Three types of spontaneous electric fields differing in strength by two orders of magnitude, the largest being nearly one-tenth of the Bohr field, were discovered with time-gated proton radiographic imaging and spectrally resolved proton self-emission. The views of the spatial structure and temporal evolution of both the laser drive in a hohlraum and implosion properties provide essential insight into, and modeling validation of, x-ray-driven implosions. (authors)

  7. Capsule Ablator Inflight Performance Measurements Via Streaked Radiography Of ICF Implosions On The NIF*

    Science.gov (United States)

    Dewald, E. L.; Tommasini, R.; Mackinnon, A.; MacPhee, A.; Meezan, N.; Olson, R.; Hicks, D.; LePape, S.; Izumi, N.; Fournier, K.; Barrios, M. A.; Ross, S.; Pak, A.; Döppner, T.; Kalantar, D.; Opachich, K.; Rygg, R.; Bradley, D.; Bell, P.; Hamza, A.; Dzenitis, B.; Landen, O. L.; MacGowan, B.; LaFortune, K.; Widmayer, C.; Van Wonterghem, B.; Kilkenny, J.; Edwards, M. J.; Atherton, J.; Moses, E. I.

    2016-03-01

    Streaked 1-dimensional (slit imaging) radiography of 1.1 mm radius capsules in ignition hohlraums was recently introduced on the National Ignition Facility (NIF) and gives an inflight continuous record of capsule ablator implosion velocities, shell thickness and remaining mass in the last 3-5 ns before peak implosion time. The high quality data delivers good accuracy in implosion metrics that meets our requirements for ignition and agrees with recently introduced 2-dimensional pinhole radiography. Calculations match measured trajectory across various capsule designs and laser drives when the peak laser power is reduced by 20%. Furthermore, calculations matching measured trajectories give also good agreement in ablator shell thickness and remaining mass.

  8. Non-spherical implosion of a dense thermonuclear plasma

    International Nuclear Information System (INIS)

    In contrast to the electronic heat conduction losses which for a tamped thermonuclear micro-explosion are minimized by a spherical target shape, the adiabatic temperature rise can be larger for a non-spherical implosion geometry, whereas for a given plasma volume and density the Bremsstrahlung losses are independent of the particular geometry. For the special case of an imploding oblate ellipsoid the optimal eccentricity is derived from an exact analytical solution. The predicted effect leads to a reduction in required beam power density, permitting less beam focusing than is necessary for spherical targets, which is of special importance for electron- and ion-beam induced micro-explosions, and may even make possible the attainment of thermonuclear temperatures by chemical explosives. (author)

  9. Hohlraum Drive and Asymmetry in High Foot Implosions on NIF

    Science.gov (United States)

    Callahan, D.; Hurricane, O.; Casey, D.; Dewald, E.; Dittrich, T.; Doeppner, T.; Haan, S.; Hinkel, D.; Berzak Hopkins, L.; Jones, O.; Kritcher, A.; Lepape, S.; Ma, T.; Macphee, A.; Milovich, J.; Pak, A.; Park, H.-S.; Patel, P.; Ralph, J.; Robey, H.; Ross, S.; Salmonson, J.; Spears, B.; Springer, P.; Tommasini, R.

    2015-11-01

    The strategy in the high foot campaign on NIF has been to take reasonably small steps away from a working design, which means that we have a very rich database to understand both capsule and hohlraum performance. Over the course of the campaign, we have changed the laser power and energy, used both gold and depleted uranium hohlraums, and varied the thickness of the ablator. Each of these changes has an impact on the hohlraum drive and drive asymmetry, as measured by the implosion shape. In this talk, we will discuss what we have learned about hohlraum performance and residual kinetic energy resulting from drive asymmetry in the high foot database. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  10. Direct-drive DT implosions with Knudsen number variations

    Science.gov (United States)

    Kim, Y.; Herrmann, H. W.; Hoffman, N. M.; Schmitt, M. J.; Bradley, P. A.; Gales, S.; Horsfield, C. J.; Rubery, M.; Leatherland, A.; Gatu Johnson, M.; Frenje, J. A.; Glebov, V. Yu

    2016-05-01

    Direct-drive implosions of DT-filled plastic-shells have been conducted at the Omega laser facility, measuring nuclear yields while varying Knudsen numbers (i.e., the ratio of mean free path of fusing ions to the length of fuel region) by adjusting both shell thickness (e.g., 7.5, 15, 20, 30 μm) and fill pressure (e.g., 2, 5, 15 atm). The fusion reactivity reduction model showed a stronger effect on yield as the Knudsen number increases (or the shell thickness decreases). The Reduced-Ion-Kinetic (RIK) simulation which includes both fusion reactivity reduction and mix model was necessary to provide a better match between the observed neutron yields and those simulated.

  11. Implosion dynamics measurements at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Callahan, D. A.; Doeppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2012-12-15

    Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% {+-} 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel {rho}R on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell

  12. Integrated implosion/heating studies for advanced fast ignition

    International Nuclear Information System (INIS)

    Integrated experiments to investigate the ultrafast heating of implosions using cone/shell geometries have been performed at the Rutherford Appleton Laboratory. The experiments used the 1054 nm, nanosecond, 0.9 kJ output of the VULCAN Nd:glass laser to drive 486 μm diameter, 6 μm wall thickness Cu-doped deuterated plastic (CD) shells in 6-beam cubic symmetry. Measurements of the opacity of the compressed plasma using two-dimensional spatially resolved Ti-Kα x-ray radiography suggest that densities of 4 g cm-3 and areal densities of 40 mg cm-2 were achieved at stagnation. Upper limits on the heating with both 1 ps and 10 ps pulses were deduced from the fluorescent yield from the Cu dopant. The data suggest that control of the preformed plasma scale-length inside the cone is necessary for efficient coupling to the compressed plasma

  13. Proton radiography of cylindrical laser-driven implosions

    Energy Technology Data Exchange (ETDEWEB)

    Volpe, L; Jafer, R [Universita di Milano-Bicocca (Italy); Vauzour, B; Nicolai, Ph; Santos, J J; Dorchies, F; Fourment, C; Hulin, S; Regan, C [CELIA, Universite de Bordeaux, CNRS, CEA, F33405 (France); Perez, F; Baton, S [LULI, Ecole Polytechnique-CNRS-UPMC, 91128 Palaiseau Cedex (France); Lancaster, K; Galimberti, M; Heathcote, R; Tolley, M; Spindloe, Ch [RAL, STFC (United Kingdom); Nazarov, W [St. Andrews University (United Kingdom); Koester, P; Labate, L; Gizzi, L A [INO-CNR, Pisa (Italy)

    2011-03-15

    We report on the results of a recent experiment at the Rutherford Appleton Laboratory investigating fast electron propagation in cylindrically compressed targets; a subject of interest for fast ignition. This experiment was performed within the framework of the road map of HiPER (the European High Power laser Energy Research facility Project). Protons accelerated by a ps-laser pulse are used to radiograph a 220 {mu}m diameter, imploded with {approx}200 J of laser light (1 ns {lambda} = 0.53 {mu}m) in four symmetrically incident beams. Results are also compared with those from hard x-ray radiography. Detailed comparison with 2D radiation hydrodyamics simulations is performed with the aid of a Monte Carlo code adapted to describe plasma effects. Finally, a simple analytical model is developed to estimate the performance of proton radiography for given implosion conditions. (brief communication)

  14. Towards an integrated model of the NIC layered implosions

    Science.gov (United States)

    Jones, O.; Callahan, D.; Cerjan, C.; Clark, D.; Edwards, M. J.; Glenzer, S.; Marinak, M.; Meezan, N.; Milovich, J.; Olson, R.; Patel, M.; Robey, H.; Sepke, S.; Spears, B.; Springer, P.; Weber, S.; Wilson, D.

    2013-11-01

    A detailed simulation-based model of the June 2011 National Ignition Campaign (NIC) cryogenic DT experiments is presented. The model is based on integrated hohlraum-capsule simulations that utilize the best available models for the hohlraum wall, ablator, and DT equations of state and opacities. The calculated radiation drive was adjusted by changing the input laser power to match the experimentally measured shock speeds, shock merger times, peak implosion velocity, and bangtime. The crossbeam energy transfer model was tuned to match the measured time-dependent symmetry. Mid-mode mix was included by directly modeling the ablator and ice surface perturbations up to mode 60. Simulated experimental values were extracted from the simulation and compared against the experiment. The model adjustments brought much of the simulated data into closer agreement with the experiment, with the notable exception of the measured yields, which were 15-40% of the calculated yields.

  15. Implosion dynamics measurements at the National Ignition Facility

    Science.gov (United States)

    Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Olson, R. E.; Callahan, D. A.; Döppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Frenje, J. A.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P.; Izumi, N.; Kalantar, D. H.; Khan, S. F.; Kline, J. L.; Kroll, J. J.; Kyrala, G. A.; Ma, T.; MacPhee, A. G.; McNaney, J. M.; Moody, J. D.; Moran, M. J.; Nathan, B. R.; Nikroo, A.; Opachich, Y. P.; Petrasso, R. D.; Prasad, R. R.; Ralph, J. E.; Robey, H. F.; Rinderknecht, H. G.; Rygg, J. R.; Salmonson, J. D.; Schneider, M. B.; Simanovskaia, N.; Spears, B. K.; Tommasini, R.; Widmann, K.; Zylstra, A. B.; Collins, G. W.; Landen, O. L.; Kilkenny, J. D.; Hsing, W. W.; MacGowan, B. J.; Atherton, L. J.; Edwards, M. J.

    2012-12-01

    Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% ± 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel ρR on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell thickness

  16. Resolving a central ICF issue for ignition: Implosion symmertry

    International Nuclear Information System (INIS)

    The Los Alamos National Laboratory Inertial Confinement Fusion (ICF) Program focuses on resolving key target-physics issues and developing technology needed for the National Ignition Facility (NIF). This work is being performed in collaboration with Lawrence Livermore National Laboratory (LLNL). A major requirement for the indirect-drive NIF ignition target is to achieve the irradiation uniformity on the capsule surface needed for a symmetrical high-convergence implosion. Los Alamos employed an integrated modeling technique using the Lasnex radiation-hydrodynamics code to design two different targets that achieve ignition and moderate gain. Los Alamos is performing experiments on the Nova Laser at LLNL in order to validate our NIF ignition calculations

  17. Demonstrating ignition hydrodynamic equivalence in direct-drive cryogenic implosions on OMEGA

    Science.gov (United States)

    Goncharov, V. N.; Regan, S. P.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Campbell, E. M.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu; Harding, D. R.; Hu, S. X.; Igumenshchev, I. V.; Marshall, F. J.; McCrory, R. L.; Michel, D. T.; Myatt, J. F.; Radha, P. B.; Seka, W.; Shvydky, A.; Stoeckl, C.; Theobald, W.; Yaakobi, B.; Gatu-Johnson, M.

    2016-05-01

    Achieving ignition in a direct-drive cryogenic implosion at the National Ignition Facility (NIF) requires reaching central stagnation pressures in excess of 100 Gbar, which is a factor of 3 to 4 less than what is required for indirect-drive designs. The OMEGA Laser System is used to study the physics of cryogenic implosions that are hydrodynamically equivalent to the spherical ignition designs of the NIF. Current cryogenic implosions on OMEGA have reached 56 Gbar, and implosions with shell convergence CR 3.5 proceed close to 1-D predictions. Demonstrating hydrodynamic equivalence on OMEGA will require reducing coupling losses caused by cross-beam energy transfer (CBET), minimizing long- wavelength nonuniformity seeded by power imbalance and target offset, and removing target debris occumulated during cryogenic target production.

  18. Performance of indirectly driven capsule implosions on NIF using adiabat-shaping

    Science.gov (United States)

    Robey, H. F.; Smalyuk, V. A.; Milovich, J. L.; Döppner, T.; Casey, D. T.; Baker, K. L.; Peterson, J. L.; Bachmann, B.; Berzak Hopkins, L. F.; Bond, E.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Gharibyan, N.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Hatarik, R.; Hurricane, O. A.; Jancaitis, K. S.; Jones, O. S.; Kerbel, G. D.; Kroll, J. J.; Lafortune, K. N.; Landen, O. L.; Ma, T.; Marinak, M. M.; MacGowan, B. J.; MacPhee, A. G.; Pak, A.; Patel, M.; Patel, P. K.; Perkins, L. J.; Sayre, D. B.; Sepke, S. M.; Spears, B. K.; Tommasini, R.; Weber, C. R.; Widmayer, C. C.; Yeamans, C.; Giraldez, E.; Hoover, D.; Nikroo, A.; Hohenberger, M.; Gatu Johnson, M.

    2016-05-01

    A series of indirectly driven capsule implosions has been performed on the National Ignition Facility to assess the relative contributions of ablation-front instability growth vs. fuel compression on implosion performance. Laser pulse shapes for both low and high-foot pulses were modified to vary ablation-front growth & fuel adiabat, separately and controllably. Two principal conclusions are drawn from this study: 1) It is shown that an increase in laser picket energy reduces ablation-front instability growth in low-foot implosions resulting in a substantial (3-10X) increase in neutron yield with no loss of fuel compression. 2.) It is shown that a decrease in laser trough power reduces the fuel adiabat in high-foot implosions results in a significant (36%) increase in fuel compression together with no reduction in neutron yield. These results taken collectively bridge the space between the higher compression low-foot results and the higher yield high-foot results.

  19. Measurements of the depth-dependent characteristics of light bulb implosion

    Science.gov (United States)

    Cho, Sungho; Kang, Donhyug

    2015-11-01

    Impulsive signals generated by the implosion of an incandescent light bulb were measured in shallow water with implosion depths in the range of 10 - 80 m. The received waveform was characterized by successive negative and positive pressure pulses originating from the bubble oscillation process. The time intervals between successive bubble pulses decreased with increasing implosion depth and the peaks of subsequent bubble oscillations dissipated relatively quickly. In this paper, semi-empirical formulas are derived to model the depth-dependent characteristics of the bulb implosion signal, including the time interval between bubble pulses and peak source level. The model predictions are compared with the measured signals and with the results in the literature. Possible causes of the differences in the comparison with previous results are discussed.

  20. Effects of seed magnetic fields on magnetohydrodynamic implosion structure and dynamics

    KAUST Repository

    Mostert, W.

    2014-12-01

    The effects of various seed magnetic fields on the dynamics of cylindrical and spherical implosions in ideal magnetohydrodynamics are investigated. Here, we present a fundamental investigation of this problem utilizing cylindrical and spherical Riemann problems under three seed field configurations to initialize the implosions. The resulting flows are simulated numerically, revealing rich flow structures, including multiple families of magnetohydrodynamic shocks and rarefactions that interact non-linearly. We fully characterize these flow structures, examine their axi- and spherisymmetry-breaking behaviour, and provide data on asymmetry evolution for different field strengths and driving pressures for each seed field configuration. We find that out of the configurations investigated, a seed field for which the implosion centre is a saddle point in at least one plane exhibits the least degree of asymmetry during implosion.

  1. Sensitivity of Inferred Electron Temperature from X-ray Emission of NIF Cryogenic DT Implosions

    Energy Technology Data Exchange (ETDEWEB)

    Klem, Michael [Univ. of Dallas, Irving, TX (United States)

    2015-05-01

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory seeks to achieve thermonuclear ignition through inertial confinement fusion. The accurate assessment of the performance of each implosion experiment is a crucial step. Here we report on work to derive a reliable electron temperature for the cryogenic deuteriumtritium implosions completed on the NIF using the xray signal from the Ross filter diagnostic. These Xrays are dominated by bremsstrahlung emission. By fitting the xray signal measured through each of the individual Ross filters, the source bremsstrahlung spectrum can be inferred, and an electron temperature of the implosion hot spot inferred. Currently, each filter is weighted equally in this analysis. We present work quantifying the errors with such a technique and the results from investigating the contribution of each filter to the overall accuracy of the temperature inference. Using this research, we also compare the inferred electron temperature against other measured implosion quantities to develop a more complete understanding of the hotspot physics.

  2. Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility

    Science.gov (United States)

    Gatu Johnson, M.; Knauer, J. P.; Cerjan, C. J.; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Kilkenny, J. D.; Munro, D. H.; Sayre, D. B.; Spears, B. K.; Bionta, R. M.; Bond, E. J.; Caggiano, J. A.; Callahan, D.; Casey, D. T.; Döppner, T.; Frenje, J. A.; Glebov, V. Yu.; Hurricane, O.; Kritcher, A.; LePape, S.; Ma, T.; Mackinnon, A.; Meezan, N.; Patel, P.; Petrasso, R. D.; Ralph, J. E.; Springer, P. T.; Yeamans, C. B.

    2016-08-01

    An accurate understanding of burn dynamics in implosions of cryogenically layered deuterium (D) and tritium (T) filled capsules, obtained partly through precision diagnosis of these experiments, is essential for assessing the impediments to achieving ignition at the National Ignition Facility. We present measurements of neutrons from such implosions. The apparent ion temperatures Tion are inferred from the variance of the primary neutron spectrum. Consistently higher DT than DD Tion are observed and the difference is seen to increase with increasing apparent DT Tion. The line-of-sight rms variations of both DD and DT Tion are small, ˜150 eV , indicating an isotropic source. The DD neutron yields are consistently high relative to the DT neutron yields given the observed Tion. Spatial and temporal variations of the DT temperature and density, DD-DT differential attenuation in the surrounding DT fuel, and fluid motion variations contribute to a DT Tion greater than the DD Tion, but are in a one-dimensional model insufficient to explain the data. We hypothesize that in a three-dimensional interpretation, these effects combined could explain the results.

  3. Control of Be capsule low mode implosions symmetry at the National Ignition Facility

    Science.gov (United States)

    Kyrala, G. A.; Kline, J. L.; Yi, S.; Simakov, A. N.; Olson, R. E.; Wilson, D. C.; Batha, S.; Dewald, E. L.; Tommasini, R.; Ralph, J. E.; MacPhee, A. G.; Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Khan, S. F.; Ma, T.; Izumi, N.; Nagel, S.; Rygg, J. R.

    2016-05-01

    We present results of the beryllium experimental campaign on the implosion symmetry properties of beryllium capsules at the National Ignition Facility (NIF) [1]. These indirect drive experiments measure both the inflight and core self-emission implosion symmetry. The inflight symmetry of the ablator before stagnation is measured using a backlight imaging technique. A copper backlighter was used to measure the transmissions (or backlit absorption) of the copper doped beryllium shells. Images of the x-ray emission from the core around bang time provide a measure of the symmetry near peak compression. Both pieces of information about the 2D symmetry are used to infer the drive and velocity uniformity enabling us to predictably adjust the properties of the incident laser, mainly the time dependent ratio of the inner beam cone power to the outer laser beam powers, to achieve proper symmetry of the implosion. Results from these experiments show inner beam propagation is not degraded compared to similar implosions with CH ablators. Variations in the shape compared with implosions using CH ablators also provides information about the cross beam energy transfer used to adjust the equatorial shape and thus infer information about the differences in plasma conditions near the laser entrance holes. Experimental results of the implosion shape for beryllium capsules will be presented along with comparisons relative to CH ablators.

  4. Maximizing 1D “like” implosion performance for inertial confinement fusion science

    Energy Technology Data Exchange (ETDEWEB)

    Kline, John L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-15

    While the march towards achieving indirectly driven inertial confinement fusion at the NIF has made great progress, the experiments show that multi-dimensional effects still dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seed by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of ICF implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. To this end, LANL has adopted three main approaches to develop a 1D implosion platform where 1D means high yield over 1D clean calculations. Taking advantage of the properties of beryllium capsules, a high adiabat, low convergence platform is being developed. The higher drive efficiency for beryllium enables larger case-to-capsule ratios to improve symmetry at the expense of drive. Smaller capsules with a high adiabat drive are expected to reduce the convergence and thus increase predictability. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the initial mass in the hot spot can be controlled via the target fielding temperature which changes the liquid vapor pressure. Varying the initial hot spot mass via the vapor pressure controls the implosion convergence and minimizes the need to vaporize the dense fuel layer during the implosion to achieve ignition relevant hot spot densities. The last method is double shell targets. Unlike hot spot ignition, double shells ignite volumetrically. The inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. Radiation trapping and the longer confinement times relax the conditions required to ignite the fuel. Key challenges for double shell targets are coupling the momentum of the outer shell to

  5. Improving the hot-spot pressure and demonstrating ignition hydrodynamic equivalence in cryogenic deuterium tritium implosions on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. N. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Sangster, T. C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Betti, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Boehly, T. R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Bonino, M. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Collins, T. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Craxton, R. S. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Delettrez, J. A. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Edgell, D. H. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Epstein, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Follett, R. K. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Forrest, C. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Froula, D. H. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Yu. Glebov, V. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Harding, D. R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Henchen, R. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Hu, S. X. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Igumenshchev, I. V. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Janezic, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Kelly, J. H. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Kessler, T. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Kosc, T. Z. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Loucks, S. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Marozas, J. A. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Marshall, F. J. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Maximov, A. V. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; McCrory, R. L. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; McKenty, P. W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Meyerhofer, D. D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Michel, D. T. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Myatt, J. F. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Nora, R. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Radha, P. B. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Regan, S. P. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Seka, W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Shmayda, W. T. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Short, R.W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Shvydky, A. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Skupsky, S. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Stoeckl, C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Yaakobi, B. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Frenje, J. A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; Gatu-Johnson, M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; Petrasso, R. D. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; Casey, D. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-05-01

    Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures in excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics of implosions that are hydrodynamically equivalent to the ignition designs on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. It is shown that the highest hot-spot pressures (up to 40 Gbar) are achieved in target designs with a fuel adiabat of α ≅ 4, an implosion velocity of 3.8 × 10⁷ cm/s, and a laser intensity of ~10¹⁵ W/cm². These moderate-adiabat implosions are well understood using two-dimensional hydrocode simulations. The performance of lower-adiabat implosions is significantly degraded relative to code predictions, a common feature between DD implosions on OMEGA and indirect-drive cryogenic implosions on the NIF. Simplified theoretical models are developed to gain physical understanding of the implosion dynamics that dictate the target performance. These models indicate that degradations in the shell density and integrity (caused by hydrodynamic instabilities during the target acceleration) coupled with hydrodynamics at stagnation are the main failure mechanisms in low-adiabat designs. To demonstrate ignition hydrodynamic equivalence in cryogenic implosions on OMEGA, the target-design robustness to hydrodynamic instability growth must be improved by reducing laser-coupling losses caused by cross beam energy transfer.

  6. Performance of Indirectly-Driven Capsule Implosions on NIF Using Adiabat-Shaping

    Science.gov (United States)

    Robey, Harry

    2015-11-01

    Indirectly-driven capsule implosions are being conducted on the National Ignition Facility (NIF). Early experiments conducted during the National Ignition Campaign (NIC) were driven by a laser pulse with a relatively low-power initial foot (``low-foot''), which was designed to keep the deuterium-tritium (DT) fuel on a low adiabat to achieve a high fuel areal density (ρR). These implosions were successful in achieving high ρR, but fell significantly short of the predicted neutron yield. A leading candidate to explain this degraded performance was ablation front instability growth, which can lead to the mixing of ablator material with the DT fuel layer and in extreme cases into the central DT hot spot. A subsequent campaign employing a modified laser pulse with increased power in the foot (``high-foot'') was designed to reduce the adverse effects of ablation front instability growth. These implosions have been very successful, increasing neutron yields by more than an order of magnitude, but at the expense of reduced fuel compression. To bridge these two regimes, a series of implosions have been designed to simultaneously achieve both high stability and high ρR. These implosions employ adiabat-shaping, where the driving laser pulse is high in the initial picket similar to the high-foot to retain the favorable stability properties at the ablation front. The remainder of the foot is similar to that of the low-foot, driving a lower velocity shock into the DT fuel to keep the adiabat low and compression high. This talk will present results and analysis of these implosions and will discuss implications for improved implosion performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  7. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-11-15

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R{sub cm}) from the downshift of the shock-produced D{sup 3}He protons. The observed ρR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ρR.

  8. Diagnosing Implosion Performance at the National Ignition Facility by Means of Advanced Neutron-Spectrometry and Neutron-Imaging Techniques

    International Nuclear Information System (INIS)

    Full text: Proper assembly of capsule mass, as manifested through the evolution of fuel areal density, is essential for achieving hot-spot ignition planned at the National Ignition Facility (NIF). Experimental information about areal density and areal-density asymmetries, hot-spot ion temperature (Ti) and yield (Yn) are therefore critical for understanding the assembly of the fuel. To obtain this information, a suite of neutron Time-of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) has been commissioned and extensively used on the NIF for measurements of the neutron spectrum in the energy range from 1.5 to 20 MeV. This range covers all essential details of the neutron spectrum, allowing for the determination of areal density, Yn, and Ti. The spectrometers are fielded at different locations around the implosion for directional measurements of the neutron spectrum, also allowing for determination of areal-density asymmetries and possible kinetic effects. The data obtained from these diagnostics have been essential to the progress of the National Ignition Campaign (NIC), indicating that the implosion performance, characterized by the Experimental Ignition Threshold Factor (ITFx), has improved about two orders of magnitude since the first cryogenic shot taken in September 2010. Areal-density values greater than 1 g/cm2 are now readily achieved. By combining the areal-density data with information about the spatial extent of the high-density region obtained from Neutron Imaging System (NIS), it has been demonstrated that densities above 500 g/cc and pressure-time (Pτ) products in excess of 10 atm s have been achieved, which are according to HYDRA simulations about a factor of three from ignition conditions. (author)

  9. Comparing neutron and X-ray images from NIF implosions

    Directory of Open Access Journals (Sweden)

    Wilson D.C.

    2013-11-01

    Full Text Available Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield.

  10. Pressure signature and evaluation of hammer pulses during underwater implosion in confining environments.

    Science.gov (United States)

    Gupta, Sachin; Matos, Helio; Shukla, Arun; LeBlanc, James M

    2016-08-01

    The fluid structure interaction phenomenon occurring in confined implosions is investigated using high-speed three-dimensional digital image correlation (DIC) experiments. Aluminum tubular specimens are placed inside a confining cylindrical structure that is partially open to a pressurized environment. These specimens are hydrostatically loaded until they naturally implode. The implosion event is viewed, and recorded, through an acrylic window on the confining structure. The velocities captured through DIC are synchronized with the pressure histories to understand the effects of confining environment on the implosion process. Experiments show that collapse of the implodable volume inside the confining tube leads to strong oscillating water hammer waves. The study also reveals that the increasing collapse pressure leads to faster implosions. Both peak and average structural velocities increase linearly with increasing collapse pressure. The effects of the confining environment are better seen in relatively lower collapse pressure implosion experiments in which a long deceleration phase is observed following the peak velocity until wall contact initiates. Additionally, the behavior of the confining environment can be viewed and understood through classical water hammer theory. A one-degree-of-freedom theoretical model was created to predict the impulse pressure history for the particular problem studied. PMID:27586733

  11. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single-exploded-wire discharges on Gamble-II suggest a common nonthermal-production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission. (author). 3 figs., 10 refs

  12. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single- exploded-wire discharges on Gamble-II suggest a common nonthermal- production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly- collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission

  13. Wire-array z-pinch: a powerful x-ray source for ICF

    International Nuclear Information System (INIS)

    The wire-array z-pinch has in a very short time achieved remarkable performance as a powerful (>200 TW), pulsed soft x-ray source of high efficiency (∼15%) and of great relevance to inertial confinement fusion. The underlying physics involves the transformation of wire cores to a plasma corona, the occurrence of uncorrelated axial instabilities, inward flowing low magnetic Reynolds number jets, sometimes an accumulated stable and dynamically confined precursor column, an almost constant velocity implosion when gaps occur in the wire cores and finally at stagnation a fast-rising soft x-ray pulse of typically 5 ns FWHM. Nested arrays improve the performance and can operate in several modes. Three hohlraum designs have been tested; one of these, the dynamic hohlraum, has achieved a radiation temperature of ∼230 eV and has compressed a capsule from 2 to ∼0.8 mm diameter with a neutron yield of > 1010 thermal DD neutrons. Lower mass stainless steel wire arrays are used for Kα radiation sources. Generally implosions lead to more energy radiated than the implosive kinetic energy, and this is hypothesized as being due to ion viscous heating, as fast-growing short wavelength nonlinear MHD instabilities are dissipated; record ion temperatures of 200-300 keV are predicted and have been measured for the stainless steel array on Z at Sandia

  14. High-Performance Layered DT Capsule Implosions in Depleted Uranium Hohlraums on the NIF

    Science.gov (United States)

    Doeppner, Tilo; Hurricane, O. A.; Callahan, D. A.; Casey, D.; Ma, T.; Park, H.-S.; Benedetti, L.; Dewald, E. L.; Dittrich, T. R.; Fittinghoff, D.; Haan, S.; Hinkel, D.; Berzak Hopkins, L.; Izumi, N.; Kritcher, A.; Le Pape, S.; Pak, A.; Patel, P.; Robey, H.; Remington, B.; Salmonson, J.; Springer, P.; Widmann, K.; Merrill, F.; Wilde, C.

    2014-10-01

    We report on the first layered DT capsule implosions in depleted uranium (DU) hohlraums driven with a high-foot pulse shape. High-foot implosions have demonstrated improved resistance to hydrodynamic instabilities. [Hurricane et al., Nature 506, 343 (2014)]. DU hohlraums provide a higher albedo and thus an increased drive equivalent to 25 TW extra laser power at the peak of the drive compared to Au hohlraums. Additionally, we observe an improved implosion shape closer to round which indicates enhanced drive from the waist. As a result, these first high-foot DU experiments achieved total neutron yields approaching 1016 neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  15. Mitigation Effect of Finite Larmor Radius on Rayleigh-Taylor Instability in Z-Pinch Implosions

    Institute of Scientific and Technical Information of China (English)

    邱孝明; 黄林; 简广德

    2002-01-01

    Based on the framework of magnetohydrodynamic theory, a simple model is proposed to study the mitigation effect of finite Larmor radius on the Rayleigh-Taylor instability in Z-pinch implosions. In this model, taking account of Ti ≥ Te in Z-pinch implosions we believe that the magnetohydrodynamic plasma responds to a perturbation (~ exp [i (k. x - ωt)]) at frequency (ω + ik2⊥ρ2iΩi) instead of frequency ω, where k2⊥ρ2i is due to the finite Larmor radius effects expressed from the generalkinetic theory of magnetized plasma. Therefore the linearized continuity and momentum equations for the perturbed mass-density and velocity include the finite Larmor radius effects. The calculations indicate that, in the wavenumber region of interest, the finite Larmor radius effects can mitigate the Rayleigh-Taylor instability in Z-pinch implosions.

  16. Demonstration of the improved rocket efficiency in direct-drive implosions using different ablator materials.

    Science.gov (United States)

    Michel, D T; Goncharov, V N; Igumenshchev, I V; Epstein, R; Froula, D H

    2013-12-13

    The success of direct-drive implosions depends critically on the ability to create high ablation pressures (∼100  Mbar) and accelerating the imploding shell to ignition-relevant velocities (>3.7×10(7 ) cm/s) using direct laser illumination. This Letter reports on an experimental study of the conversion of absorbed laser energy into kinetic energy of the shell (rocket efficiency) where different ablators were used to vary the ratio of the atomic number to the atomic mass. The implosion velocity of Be shells is increased by 20% compared to C and CH shells in direct-drive implosions when a constant initial target mass is maintained. These measurements are consistent with the predicted increase in the rocket efficiency of 28% for Be and 5% for C compared to a CH ablator.

  17. Implosion dynamics measurements by monochromatic x-ray radiography in inertial confinement fusion

    Science.gov (United States)

    Chen, Bolun; Yang, Zhenghua; Wei, Minxi; Pu, Yudong; Hu, Xin; Chen, Tao; Liu, Shenye; Yan, Ji; Huang, Tianxuan; Jiang, Shaoen; Ding, Yongkun

    2014-12-01

    The implosion dynamics is the most important metrics for assessing the progress toward ignition of an inertially confined fusion experiment. A high spatial resolution monochromatic x-ray imaging system based on the spherically bent crystal is developed to measure the implosion trajectory. The density distribution of the imploding capsules can be inferred with more accurately from monochromatic trajectories. The self emission of the imploded core will be restrained by spectral resolution and the setup of the imaging system. Also the variations of the backlighters' intensity will not be seen in the images. It has been demonstrated on SGII laser facility at the first time. The ablator remaining mass and the implosion velocity, which are the important ablator parameters, are calculated from the monochromatic trajectories. And the results are contrasted to the 1D hydrodynamics simulations.

  18. Simulation of Wire-Array Z Pinches with ALEGRA

    Science.gov (United States)

    Chantrenne, Sophie; Bliss, David; Cochrane, Kyle; Coverdale, Christine; Deeney, Chris; Hall, Clint; Haill, Thomas; Jones, Brent; Lepell, Paul; Oliver, Bryan; Sinars, Daniel

    2006-10-01

    Wire-array z pinches provide the x-ray radiation drive for Inertial Confinement Fusion Experiments at Sandia National Laboratories. A physical understanding of the physics of wire-array z pinches is important in providing a future radiation source capable of driving high-yield fusion capsules. Modeling of wire-array implosions on the Z machine were performed using the 2-D radiation MHD code Alegra. These new calculations use more accurate initial conditions that are more representative of the experimental data, allowing us to model the implosion through stagnation, to avoid radiation collapse, and to generate a radiation pulse that compares well with data. Code predictions will be compared with tungsten & aluminum wire-array data from Z. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract No. DE-AC04- 94AL85000. a Ktech Corporation, 1300 Eubank Blvd. S.E., Albuquerque, NM 87123-3336

  19. Ti Kα radiography of Cu-doped plastic microshell implosions via spherically bent crystal imaging

    International Nuclear Information System (INIS)

    We show that short pulse laser generated Ti Kα radiation can be used effectively as a backlighter for radiographic imaging. This method of x-ray radiography features high temporal and spatial resolution, high signal to noise ratio, and monochromatic imaging. We present here the Ti Kα backlit images of six-beam driven spherical implosions of thin-walled 500-μm Cu-doped deuterated plastic (CD) shells and of similar implosions with an included hollow gold cone. These radiographic results were used to define conditions for the diagnosis of fast ignition relevant electron transport within imploded Cu-doped coned CD shells

  20. Simulation and assessment of ion kinetic effects in a direct-drive capsule implosion experiment

    CERN Document Server

    Le, Ari; Schmitt, M J; Herrmann, H W; Batha, S H

    2016-01-01

    The first simulations employing a kinetic treatment of both fuel and shell ions to model inertial confinement fusion experiments are presented, including results showing the importance of kinetic physics processes in altering fusion burn. A pair of direct drive capsule implosions performed at the OMEGA facility with two different gas fills of deuterium, tritium, and helium-3 are analyzed. During implosion shock convergence, highly non-Maxwellian ion velocity distributions and separations in the density and temperature amongst the ion species are observed. Diffusion of fuel into the capsule shell is identified as a principal process that degrades fusion burn performance.

  1. Hot dense capsule implosion cores produced by z-pinch dynamic hohlraum radiation

    CERN Document Server

    Bailey, J E; Slutz, S A; Golovkin, I; Lake, P W; MacFarlane, J J; Mancini, R C; Buris-Mog, T J; Cooper, G; Leeper, R J; Mehlhorn, T A; Moore, T C; Nash, T J; Nielsen, D S; Ruiz, C L; Schroen, D G; Varnum, W A

    2003-01-01

    Hot dense capsule implosions driven by z-pinch x-rays have been measured for the first time. A ~220 eV dynamic hohlraum imploded 1.7-2.1 mm diameter gas-filled CH capsules which absorbed up to ~20 kJ of x-rays. Argon tracer atom spectra were used to measure the Te~ 1keV electron temperature and the ne ~ 1-4 x10^23 cm-3 electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak compression values of Te, ne, and symmetry, indicating reasonable understanding of the hohlraum and implosion physics.

  2. Multiresolution Analysis Techniques to Isolate, Detect and Characterize Morphologically Diverse Features of Structured ICF Capsule Implosions

    CERN Document Server

    Afeyan, Bedros; Jones, Peter; Starck, Jean Luc; Herrmann, Mark

    2012-01-01

    In order to capture just how nonuniform and degraded the symmetry may become of an imploding inertial confinement fusion capsule one may resort to the analysis of high energy X ray point projection backlighting generated radiographs. Here we show new results for such images by using methods of modern harmonic analysis which involve different families of wavelets, curvelets and WaSP (wavelet square partition) functions from geometric measure theory. Three different methods of isolating morphologically diverse features are suggested together with statistical means of quantifying their content for the purposes of comparing the same implosion at different times, to simulations and to different implosion images.

  3. Implosion lessons from national security, high reliability spacecraft, electronics, and the forces which changed them

    CERN Document Server

    Temple, L Parker

    2012-01-01

    Implosion is a focused study of the history and uses of high-reliability, solid-state electronics, military standards, and space systems that support our national security and defense. This book is unique in combining the interdependent evolution of and interrelationships among military standards, solid-state electronics, and very high-reliability space systems. Starting with a brief description of the physics that enabled the development of the first transistor, Implosion covers the need for standardizing military electronics, which began during World War II and continu

  4. Hot dense capsule-implosion cores produced by Z-pinch dynamic hohlraum radiation

    International Nuclear Information System (INIS)

    Hot dense capsule implosions driven by Z-pinch x rays have been measured using a ∼220 eV dynamic hohlraum to implode 1.7-2.1 mm diameter gas-filled CH capsules. The capsules absorbed up to ∼20 kJ of x rays. Argon tracer atom spectra were used to measure the Te∼1 keV electron temperature and the ne∼1-4x1023 cm-3 electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak emission values of Te, ne, and symmetry, indicating reasonable understanding of the hohlraum and implosion physics

  5. Progress in detailed modelling of low foot and high foot implosion experiments on the National Ignition Facility

    Science.gov (United States)

    Clark, D. S.; Weber, C. R.; Eder, D. C.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Jones, O. S.; Kritcher, A. L.; Marinak, M. M.; Milovich, J. L.; Patel, P. K.; Robey, H. F.; Salmonson, J. D.; Sepke, S. M.

    2016-05-01

    Several dozen high convergence inertial confinement fusion ignition experiments have now been completed on the National Ignition Facility (NIF). These include both “low foot” experiments from the National Ignition Campaign (NIC) and more recent “high foot” experiments. At the time of the NIC, there were large discrepancies between simulated implosion performance and experimental data. In particular, simulations over predicted neutron yields by up to an order of magnitude, and some experiments showed clear evidence of mixing of ablator material deep into the hot spot that could not be explained at the time. While the agreement between data and simulation improved for high foot implosion experiments, discrepancies nevertheless remain. This paper describes the state of detailed modelling of both low foot and high foot implosions using 1-D, 2-D, and 3-D radiation hydrodynamics simulations with HYDRA. The simulations include a range of effects, in particular, the impact of the plastic membrane used to support the capsule in the hohlraum, as well as low-mode radiation asymmetries tuned to match radiography measurements. The same simulation methodology is applied to low foot NIC implosion experiments and high foot implosions, and shows a qualitatively similar level of agreement for both types of implosions. While comparison with the experimental data remains imperfect, a reasonable level of agreement is emerging and shows a growing understanding of the high-convergence implosions being performed on NIF.

  6. Laser/x-ray coupling in the first NIF beryllium implosions

    Science.gov (United States)

    Wilson, D. C.; Kline, J. L.; Yi, S. A.; Simakov, A. N.; Olson, R. E.; Kyrala, G. A.; Perry, T. S.; Batha, S.; Callahan, D. A.; Dewald, E. L.; Jones, O.; Hinkel, D. E.; Hurricane, O. A.; Izumi, N.; Macphee, A. G.; Milovich, J. L.; Ralph, J. E.; Rygg, J. R.; Schneider, M. B.; Strozzi, D. J.; Thomas, C. A.; Tommasini, R.

    2015-11-01

    The x-ray flux driving a capsule is currently overestimated in standard Hydra high-flux model (Rosen et al., HEDP 7,180 (2011)) calculations of gas-filled hohlraums. Jones et al. (Phys. Plasmas,19,056315 (2012)) introduced time dependent multipliers to reduce the laser drive and achieve an appropriate radiation drive on NIF capsules. Using shock velocities from VISAR capsule experiments, symmetry capsule implosion times with truncated laser pulses, and time dependent DANTE X-ray flux measurements from 1D and 2D convergent ablator implosions, we derived a set of time dependent flux multipliers for the first NIF cryogenically layered beryllium capsule implosion. The similarity between these multipliers for both plastic and beryllium capsules suggests that they are primarily correcting for improper modeling of the hohlraum physics, with possibly some residual contribution from capsule modeling deficiencies. Using Lasnex we have adjusted hohlraum physics and resolution in an attempt to model these implosions without drive multipliers. This work was funded by the US Department of Energy.

  7. Assessment of transient effects on the x-ray spectroscopy of implosion cores at OMEGA

    Science.gov (United States)

    Florido, R.; Mancini, R. C.

    2015-11-01

    An assessment of transient effects on the atomic kinetics of argon tracers in inertial confinement fusion implosion cores is carried out. The focus is on typical electron temperature and density conditions achieved in high- and low-adiabat, and shock-ignition implosion experiments performed at the OMEGA laser facility (Laboratory for Laser Energetics, USA). The results show that no significant time-dependent effects are present through the deceleration and burning phases of the implosion, and thus justify the use of steady-state atomic kinetics models in the spectroscopic analysis of sets of time-resolved x-ray spectra recorded with streaked or gated spectrometers. Modeling calculations suggest an onset for time-dependent effects to become important at electron densities ≲1022 cm-3. A physical interpretation of these results is given based on the atomic kinetics timescales extracted from the eigenvalue spectrum of the collisional-radiative rate matrix. This study is also relevant for past implosion experiments performed at the GEKKO XII laser (Institute of Laser Engineering, Japan), as well as those currently being performed at the National Ignition Facility (Lawrence Livermore National Laboratory, USA).

  8. Three-dimensional simulations of low foot and high foot implosion experiments on the National Ignition Facility

    Science.gov (United States)

    Clark, D. S.; Weber, C. R.; Milovich, J. L.; Salmonson, J. D.; Kritcher, A. L.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Hurricane, O. A.; Jones, O. S.; Marinak, M. M.; Patel, P. K.; Robey, H. F.; Sepke, S. M.; Edwards, M. J.

    2016-05-01

    In order to achieve the several hundred Gbar stagnation pressures necessary for inertial confinement fusion ignition, implosion experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] require the compression of deuterium-tritium fuel layers by a convergence ratio as high as forty. Such high convergence implosions are subject to degradation by a range of perturbations, including the growth of small-scale defects due to hydrodynamic instabilities, as well as longer scale modulations due to radiation flux asymmetries in the enclosing hohlraum. Due to the broad range of scales involved, and also the genuinely three-dimensional (3D) character of the flow, accurately modeling NIF implosions remains at the edge of current simulation capabilities. This paper describes the current state of progress of 3D capsule-only simulations of NIF implosions aimed at accurately describing the performance of specific NIF experiments. Current simulations include the effects of hohlraum radiation asymmetries, capsule surface defects, the capsule support tent and fill tube, and use a grid resolution shown to be converged in companion two-dimensional simulations. The results of detailed simulations of low foot implosions from the National Ignition Campaign are contrasted against results for more recent high foot implosions. While the simulations suggest that low foot performance was dominated by ablation front instability growth, especially the defect seeded by the capsule support tent, high foot implosions appear to be dominated by hohlraum flux asymmetries, although the support tent still plays a significant role. For both implosion types, the simulations show reasonable, though not perfect, agreement with the data and suggest that a reliable predictive capability is developing to guide future implosions toward ignition.

  9. Improving the hot-spot pressure and demonstrating ignition hydrodynamic equivalence in cryogenic deuterium–tritium implosions on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. N.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Follett, R. K.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu.; Harding, D. R.; Henchen, R. J.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others

    2014-05-15

    Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures in excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics of implosions that are hydrodynamically equivalent to the ignition designs on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. It is shown that the highest hot-spot pressures (up to 40 Gbar) are achieved in target designs with a fuel adiabat of α ≃ 4, an implosion velocity of 3.8 × 10{sup 7} cm/s, and a laser intensity of ∼10{sup 15} W/cm{sup 2}. These moderate-adiabat implosions are well understood using two-dimensional hydrocode simulations. The performance of lower-adiabat implosions is significantly degraded relative to code predictions, a common feature between DD implosions on OMEGA and indirect-drive cryogenic implosions on the NIF. Simplified theoretical models are developed to gain physical understanding of the implosion dynamics that dictate the target performance. These models indicate that degradations in the shell density and integrity (caused by hydrodynamic instabilities during the target acceleration) coupled with hydrodynamics at stagnation are the main failure mechanisms in low-adiabat designs. To demonstrate ignition hydrodynamic equivalence in cryogenic implosions on OMEGA, the target-design robustness to hydrodynamic instability growth must be improved by reducing laser-coupling losses caused by cross beam energy transfer.

  10. Three-dimensional modeling of direct-drive cryogenic implosions on OMEGA

    Science.gov (United States)

    Igumenshchev, I. V.; Goncharov, V. N.; Marshall, F. J.; Knauer, J. P.; Campbell, E. M.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu.; McCrory, R. L.; Regan, S. P.; Sangster, T. C.; Skupsky, S.; Stoeckl, C.

    2016-05-01

    The effects of large-scale (with Legendre modes ≲ 10 ) laser-imposed nonuniformities in direct-drive cryogenic implosions on the OMEGA Laser System are investigated using three-dimensional hydrodynamic simulations performed using the newly developed code ASTER. Sources of these nonuniformities include an illumination pattern produced by 60 OMEGA laser beams, capsule offsets (˜10-20 μm), and imperfect pointing, power balance, and timing of the beams (with typical σ rms ˜ 10 μm, 10%, and 5 ps, respectively). Two implosion designs using 26-kJ triple-picket laser pulses were studied: a nominal design, in which an 874-μm-diameter capsule is illuminated by about the same-diameter beams, and a more hydrodynamically efficient "R75" design using a 900-μm-diameter capsule and beams of 75% of this diameter. Simulations show that nonuniformities caused by capsule offsets and beam imbalance have the largest effect on implosion performance. These nonuniformities lead to significant distortions of implosion cores, resulting in an increased residual kinetic energy and incomplete stagnation. The shape of distorted cores can be well characterized using neutron images but is less represented by 4-8 keV x-ray images. Simulated neutron spectra from perturbed implosions show large directional variations because of bulk motion effects and up to an ˜2 keV variation of the hot-spot temperature inferred from these spectra. The R75 design suffers more from illumination nonuniformities. Simulations show an advantage of this design over the nominal design when the target offset and beam power imbalance σ rms are reduced to less than 5 μm and 5%, respectively.

  11. An Investigation Into Bayesian Networks for Modeling National Ignition Facility Capsule Implosions

    Energy Technology Data Exchange (ETDEWEB)

    Mitrani, J

    2008-08-18

    Bayesian networks (BN) are an excellent tool for modeling uncertainties in systems with several interdependent variables. A BN is a directed acyclic graph, and consists of a structure, or the set of directional links between variables that depend on other variables, and conditional probabilities (CP) for each variable. In this project, we apply BN's to understand uncertainties in NIF ignition experiments. One can represent various physical properties of National Ignition Facility (NIF) capsule implosions as variables in a BN. A dataset containing simulations of NIF capsule implosions was provided. The dataset was generated from a radiation hydrodynamics code, and it contained 120 simulations of 16 variables. Relevant knowledge about the physics of NIF capsule implosions and greedy search algorithms were used to search for hypothetical structures for a BN. Our preliminary results found 6 links between variables in the dataset. However, we thought there should have been more links between the dataset variables based on the physics of NIF capsule implosions. Important reasons for the paucity of links are the relatively small size of the dataset, and the sampling of the values for dataset variables. Another factor that might have caused the paucity of links is the fact that in the dataset, 20% of the simulations represented successful fusion, and 80% didn't, (simulations of unsuccessful fusion are useful for measuring certain diagnostics) which skewed the distributions of several variables, and possibly reduced the number of links. Nevertheless, by illustrating the interdependencies and conditional probabilities of several parameters and diagnostics, an accurate and complete BN built from an appropriate simulation set would provide uncertainty quantification for NIF capsule implosions.

  12. Response Of A CVD Diamond Detector To ''Typical'' Deuterium-Tritium NIF Implosions For Areal Density Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dauffy, L S; Lerche, R A; Phillips, T W

    2005-04-11

    CVD diamond detector signals from Deuterium-Tritium implosions have been simulated in order to study the feasibility of measuring areal density using the ratio of downscattered to primary neutrons during the ignition campaign at the NIF. Simulated neutron spectra for three ''typical'' DT implosions were weighted with the CVD diamond sensitivity to obtain an estimated signal at several distances from the target chamber center. The 14 MeV peak was found to have an amplitude about three orders of magnitude larger than the down-scattered signal for the three spectra. At a target to detector distance of 17 m (just outside the target bay wall) and for a 1 cm{sup 2} wafer, signals are large enough to be recorded, well above any background and electronic noise. The uncertainty in the areal density measurement comes mainly from the uncertainty in the CVD diamond energy dependent sensitivity, the accuracy of the background simulation, and the effect of the saturation of both detector and electronics after the large 14 MeV peak. Nevertheless, the results found in this study are encouraging, and the remaining sources of uncertainty should now be addressed.

  13. Imaging of high-energy x-ray emission from cryogenic thermonuclear fuel implosions on the NIF.

    Science.gov (United States)

    Ma, T; Izumi, N; Tommasini, R; Bradley, D K; Bell, P; Cerjan, C J; Dixit, S; Döppner, T; Jones, O; Kline, J L; Kyrala, G; Landen, O L; LePape, S; Mackinnon, A J; Park, H-S; Patel, P K; Prasad, R R; Ralph, J; Regan, S P; Smalyuk, V A; Springer, P T; Suter, L; Town, R P J; Weber, S V; Glenzer, S H

    2012-10-01

    Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide broadband time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered implosions. This diagnostic measures the temperature- and density-sensitive bremsstrahlung emission and provides estimates of hot spot mass, mix mass, and pressure.

  14. Reconstruction of quasimonochromatic images for multispectral x-ray imaging with a pinhole array and a flat Bragg mirror

    International Nuclear Information System (INIS)

    We have developed a software package for reconstruction of quasimonochromatic images from a multiple monochromatic x-ray imager for inertial confinement fusion implosions. The instrument consists of a pinhole array, a multilayer Bragg mirror, and an image detector. The pinhole array projects hundreds of images onto the detector after reflection off the multilayer Bragg mirror, which introduces spectral dispersion along the reflection axis. The quasimonochromatic images of line emissions and continuum emissions can be used for measurement of temperature and density maps of implosion plasmas. In this article, we describe a computer-aided processing technique for systematic reconstruction of quasimonochromatic images from raw data. This technique provides flexible spectral bandwidth selection and allows systematic subtraction of continuum emission from line emission images

  15. Lasers and laser applications. Imaging implosion dynamics: The x-ray pinhole/streak camera

    International Nuclear Information System (INIS)

    A Livermore-developed x-ray-sensitive streak camera was combined with a unique x-ray pinhole camera to make dynamic photographs of laser-irradiated fusion target implosions. These photographs show x radiation emitted from the imploding shell during its 100-ps implosion; they are the first continuous observations of an imploding laser-driven fusion capsule. The diagnostic system has a time resolution of 15 ps and a spatial resolution of about 6 μm. Results agree very well with those predicted by our LASNEX calculations, confirming that the essential physics are correctly described in the code and providing further confidence in the soundness of this approach to inertial confinement fusion

  16. A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF.

    Science.gov (United States)

    Zylstra, A B; Gatu Johnson, M; Frenje, J A; Séguin, F H; Rinderknecht, H G; Rosenberg, M J; Sio, H W; Li, C K; Petrasso, R D; McCluskey, M; Mastrosimone, D; Glebov, V Yu; Forrest, C; Stoeckl, C; Sangster, T C

    2014-06-01

    A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility [T. Boehly et al., Opt. Commun. 133, 495 (1997)]. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is currently capable of measuring the yield to ~±10% accuracy, and mean neutron energy to ~±50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energy uncertainty to ±15-20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ~±25-40 km/s.

  17. Electromagnetically driven linear implosion and magnetic flux compression towards magnetized target fusion

    International Nuclear Information System (INIS)

    One of the schemes in the inertial confinement fusion is to prove that substantial heating and increased nt will result from liner implosion of well-formed target plasma. The experiments conducted on different imploding solid liners with available sources and the numerical analysis of the implosion systems help us to have a preliminary insight into the physics issues associated with the accelerating liners. This work is basically aimed at gaining the experimental knowledge base and developing well-benchmarked computer models of liner physics. Experiments have been conducted on cylindrical liners accelerated by 280 kJ/ 40 kV capacitor bank synchronized with another feeder bank providing the initial field, with an aim to demonstrate the magnetic flux compression. Experimental results are compared with numerical simulation of these configurations and are presented in this paper. (author)

  18. Hohlraum-driven ignition-like double-shell implosions on the Omega laser facility

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, P; Robey, H F; Park, H S; Tipton, R E; Turner, R E; Milovich, J L; Bono, M; Hibbard, R; Louis, H; Wallace, R

    2004-10-01

    High-convergence ignition-like double-shell implosion experiments have been performed on the Omega laser facility [T.R. Boehly et al., Opt. Commun. 133, 495 (1997)] using cylindrical gold hohlraums with 40 drive beams. Repeatable, dominant primary (2.45 MeV) neutron production from the mix-susceptible compressional phase of a double-shell implosion, using fall-line design optimization and exacting fabrication standards, is experimentally inferred from time-resolved core x-ray imaging. Effective control of fuel-pusher mix during final compression is essential for achieving noncryogenic ignition with double-shell targets on the National Ignition Facility [Paisner et al., Laser Focus World 30, 75 (1994)].

  19. A strategy for reducing stagnation phase hydrodynamic instability growth in inertial confinement fusion implosions

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D. S.; Robey, H. F.; Smalyuk, V. A. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

    2015-05-15

    Encouraging progress is being made in demonstrating control of ablation front hydrodynamic instability growth in inertial confinement fusion implosion experiments on the National Ignition Facility [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, and R. Al-Ayat, Phys. Plasmas 16, 041006 (2009)]. Even once ablation front stabilities are controlled, however, instability during the stagnation phase of the implosion can still quench ignition. A scheme is proposed to reduce the growth of stagnation phase instabilities through the reverse of the “adiabat shaping” mechanism proposed to control ablation front growth. Two-dimensional radiation hydrodynamics simulations confirm that improved stagnation phase stability should be possible without compromising fuel compression.

  20. Analysis of Ar line spectra from indirectly-driven implosion experiments on SGII facility

    Institute of Scientific and Technical Information of China (English)

    Pu Yu-Dong; Zhang Ji-Yan; Yang Jia-Min; Huang Tian-Xuan; Ding Yong-Kun

    2011-01-01

    This paper reports on the indirectly-driven implosion experiments on SGII laser facility in which Ar emission spectrum from Ar-doped D-filled plastic capsule is recorded with the crystal spectrometer. Spectral features of Ar Heβ line and its associated satellites are analysed to extract the electron temperature and density of the implosion core. Non local thermal equilibrium (NLTE) collisional-radiative atomic kinetics and Strark broadening line shape are included in the present calculation. By comparing the calculated spectrum with the measured one, the core electron temperature and density are inferred to be 700 eV and 2.5 × 1023 cm-3 respectively. With these inferred values of electron temperature and density, neutron yield can be estimated to agree with the measured value in magnitude despite of the very simple model used for the estimation.

  1. X-ray absorption lines - Signature for preheat level in non-explosive laser implosions

    Science.gov (United States)

    Yaakobi, B.; McCrory, R. L.; Skupsky, S.; Delettrez, J. A.; Bourke, P.; Soures, J. M.; Hooper, C. F.; Deckman, H.

    1980-08-01

    The measured X-ray spectrum from thick glass shells imploded with two TW six-beam laser pulses displayed absorption by transitions of Si ions. This indicates the existence around the time of peak compression of a cooler (less than approximately 200 eV) layer surrounding the hot innermost glass layer, of density times thickness approximately 0.0006 g/sq cm. This temperature is indicative of the preheat level ealier in the implosion.

  2. Array tomography: imaging stained arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. In this protocol, tissue arrays are imaged using conventional wide-field fluorescence microscopy. Images can be captured manually or, with the appropriate software and hardware, the process can be automated. PMID:21041399

  3. Array tomography: production of arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time consuming and require some practice to perfect. This protocol describes the sectioning of embedded tissues and the mounting of the serial arrays. The procedures require some familiarity with the techniques used for ultramicrotome sectioning for electron microscopy. PMID:21041397

  4. Diagnosis of pusher-fuel mix in indirectly driven Nova implosions (HEP3)

    Energy Technology Data Exchange (ETDEWEB)

    Dittrich, T.R.; Hammel, B.A.; Keane, C.J. [and others

    1996-06-01

    A key issue for inertial confinement fusion (ICF) is the hydrodynamic stability of the imploding capsule. Imperfections on the capsule surface can grow into large perturbations that degrade capsule performance. Understanding this process is crucial if the authors are to successfully predict requirements for future high-gain ICF capsules. Experiments on the Nova laser at Lawrence Livermore National Laboratory have directly measured perturbation growth on planar foils, and three experimental groups have investigated backlit perturbation growth using imploding spheres. In addition to these efforts, which concentrate on indirectly driven implosions, is work investigating the hydrodynamic stability of directly driven ICF capsules. In these direct-drive experiments the laser light shines directly on the capsules, causing the implosion and providing the seed for perturbation growth. This article reports measurement, via emission from spectroscopic tracers, of the full process of perturbation growth leading to pusher-fuel mix in spherical implosions, and shows perturbation growth dependence on initial perturbation amplitude and wavelength. In contrast to the cited direct-drive work, the authors have in this experiment separated the drive from the perturbation seed.

  5. Study of the current-sheath formation during the implosion of multishell gas puffs

    Science.gov (United States)

    Labetsky, A. Yu.; Kokshenev, V. A.; Kurmaev, N. E.; Oreshkin, V. I.; Rousskikh, A. G.; Fedyunin, A. V.; Fursov, F. I.; Chaikovsky, S. A.; Shishlov, A. V.; Zhidkova, N. A.

    2008-03-01

    Results are presented from experimental studies of the dynamics of large-diameter multishell gas puffs imploded by microsecond megampere current pulses. The experiments were conducted on the GIT-12 generator in the regime of microsecond implosion ( t imp = 1.1-1.2 μs, I 0 = 3.4-3.7 MA). The influence of the load configuration on the dynamics of current losses and gas-puff radiative characteristics was studied. The correlation between the radial compression ratio (the ratio between the initial and final Z-pinch radii) and the magnitude of the current flowing at the plasma periphery was investigated. The experiments show that, in a multishell gas puff, large-scale instabilities insignificantly affect the gas-puff implosion even over microsecond time intervals and that a compact dense pinch with a relatively high average electron temperature (400-600 eV) forms at the Z-pinch axis. The diameter of the plasma column radiating in the K-shell lines of neon is about 3-4 mm, the K-shell radiation yield being 5-11 kJ/cm. In the final stage of implosion, only a small portion of the current flows through the high-temperature central region of the pinch plasma, whereas the major part of the generator current flows through the residual peripheral plasma.

  6. Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims

    Science.gov (United States)

    Clark, D. S.; Weber, C. R.; Smalyuk, V. A.; Robey, H. F.; Kritcher, A. L.; Milovich, J. L.; Salmonson, J. D.

    2016-07-01

    Current indirect drive implosion experiments on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are believed to be strongly impacted by long wavelength perturbations driven by asymmetries in the hohlraum x-ray flux. To address this perturbation source, active efforts are underway to develop modified hohlraum designs with reduced asymmetry imprint. An alternative strategy, however, is to modify the capsule design to be more resilient to a given amount of hohlraum asymmetry. In particular, the capsule may be deliberately misshaped, or "shimmed," so as to counteract the expected asymmetries from the hohlraum. Here, the efficacy of capsule shimming to correct the asymmetries in two recent NIF implosion experiments is assessed using two-dimensional radiation hydrodynamics simulations. Despite the highly time-dependent character of the asymmetries and the high convergence ratios of these implosions, simulations suggest that shims could be highly effective at counteracting current asymmetries and result in factors of a few enhancements in neutron yields. For higher compression designs, the yield improvement could be even greater.

  7. Three-dimensional simulations of National Ignition Facility implosions: Insight into experimental observables

    International Nuclear Information System (INIS)

    We simulate in 3D both the hydrodynamics and, simultaneously, the X-ray and neutron diagnostic signatures of National Ignition Facility (NIF) implosions. We apply asymmetric radiation drive to study the impact of low mode asymmetry on diagnostic observables. We examine X-ray and neutron images as well as neutron spectra for these perturbed implosions. The X-ray images show hot spot evolution on small length scales and short time scales, reflecting the incomplete stagnation seen in the simulation. The neutron images show surprising differences from the X-ray images. The neutron spectra provide additional measures of implosion asymmetry. Flow in the hot spot alters the neutron spectral peak, namely, the peak location and width. The changes in the width lead to a variation in the apparent temperature with viewing angle that signals underlying hot spot asymmetry. We compare our new expectations based on the simulated data with NIF data. We find that some recent cryogenic layered experiments show appreciable temperature anisotropy indicating residual flow in the hot spot. We also find some trends in the data that do not reflect our simulation and theoretical understanding

  8. Time history prediction of direct-drive implosions on the Omega facility

    Energy Technology Data Exchange (ETDEWEB)

    Laffite, S.; Bourgade, J. L.; Caillaud, T.; Girard, F.; Landoas, O.; Lemaire, S.; Masse, L.; Masson-Laborde, P. E.; Philippe, F.; Reverdin, C.; Tassin, V. [CEA, DAM, DIF, F-91297 Arpajon (France); Delettrez, J. A.; Glebov, V. Yu.; Marshall, F. J.; Michel, D. T.; Seka, W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Frenje, J. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Joshi, T.; Mancini, R. C. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Legay, G. [CEA, CVA, 21120 Is-sur-Tille (France)

    2016-01-15

    We present in this article direct-drive experiments that were carried out on the Omega facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Two different pulse shapes were tested in order to vary the implosion stability of the same target whose parameters, dimensions and composition, remained the same. The direct-drive configuration on the Omega facility allows the accurate time-resolved measurement of the scattered light. We show that, provided the laser coupling is well controlled, the implosion time history, assessed by the “bang-time” and the shell trajectory measurements, can be predicted. This conclusion is independent on the pulse shape. In contrast, we show that the pulse shape affects the implosion stability, assessed by comparing the target performances between prediction and measurement. For the 1-ns square pulse, the measured neutron number is about 80% of the prediction. For the 2-step 2-ns pulse, we test here that this ratio falls to about 20%.

  9. Neutron temporal diagnostic for high-yield deuterium-tritium cryogenic implosions on OMEGA

    Science.gov (United States)

    Stoeckl, C.; Boni, R.; Ehrne, F.; Forrest, C. J.; Glebov, V. Yu.; Katz, J.; Lonobile, D. J.; Magoon, J.; Regan, S. P.; Shoup, M. J.; Sorce, A.; Sorce, C.; Sangster, T. C.; Weiner, D.

    2016-05-01

    A next-generation neutron temporal diagnostic (NTD) capable of recording high-quality data for the highest anticipated yield cryogenic deuterium-tritium (DT) implosion experiments was recently installed at the Omega Laser Facility. A high-quality measurement of the neutron production width is required to determine the hot-spot pressure achieved in inertial confinement fusion experiments—a key metric in assessing the quality of these implosions. The design of this NTD is based on a fast-rise-time plastic scintillator, which converts the neutron kinetic energy to 350- to 450-nm-wavelength light. The light from the scintillator inside the nose-cone assembly is relayed ˜16 m to a streak camera in a well-shielded location. An ˜200× reduction in neutron background was observed during the first high-yield DT cryogenic implosions compared to the current NTD installation on OMEGA. An impulse response of ˜40 ± 10 ps was measured in a dedicated experiment using hard x-rays from a planar target irradiated with a 10-ps short pulse from the OMEGA EP laser. The measured instrument response includes contributions from the scintillator rise time, optical relay, and streak camera.

  10. Soft x-ray backlighting of cryogenic implosions using a narrowband crystal imaging system (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Stoeckl, C., E-mail: csto@lle.rochester.edu; Bedzyk, M.; Brent, G.; Epstein, R.; Fiksel, G.; Guy, D.; Goncharov, V. N.; Hu, S. X.; Ingraham, S.; Jacobs-Perkins, D. W.; Jungquist, R. K.; Marshall, F. J.; Mileham, C.; Nilson, P. M.; Sangster, T. C.; Shoup, M. J.; Theobald, W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2014-11-15

    A high-performance cryogenic DT inertial confinement fusion implosion experiment is an especially challenging backlighting configuration because of the high self-emission of the core at stagnation and the low opacity of the DT shell. High-energy petawatt lasers such as OMEGA EP promise significantly improved backlighting capabilities by generating high x-ray intensities and short emission times. A narrowband x-ray imager with an astigmatism-corrected bent quartz crystal for the Si He{sub α} line at ∼1.86 keV was developed to record backlit images of cryogenic direct-drive implosions. A time-gated recording system minimized the self-emission of the imploding target. A fast target-insertion system capable of moving the backlighter target ∼7 cm in ∼100 ms was developed to avoid interference with the cryogenic shroud system. With backlighter laser energies of ∼1.25 kJ at a 10-ps pulse duration, the radiographic images show a high signal-to-background ratio of >100:1 and a spatial resolution of the order of 10 μm. The backlit images can be used to assess the symmetry of the implosions close to stagnation and the mix of ablator material into the dense shell.

  11. Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

    Energy Technology Data Exchange (ETDEWEB)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Hohenberger, M.; Boehly, T. R. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Nikroo, A. [General Atomics, San Diego, California 92196 (United States)

    2014-02-15

    Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

  12. The Submillimeter Array

    CERN Document Server

    Ho, P T P; Lo, K Y; Ho, Paul T.P.; Moran, James M.; Lo, Kwok Yung

    2004-01-01

    The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m telescopes comprise the array, which will cover the frequency range of 180-900 GHz. All eight telescopes have been deployed and are operational. First scientific results utilizing the three receiver bands at 230, 345, and 690 GHz have been obtained and are presented in the accompanying papers.

  13. Use of Faraday probing to estimate current distribution in wire array z pinches

    International Nuclear Information System (INIS)

    In order to understand the formation and dynamics of plasma in wire array z-pinch experiments, measurements of the distribution of current throughout the array are required. We present details of two Faraday probing diagnostics aimed at exploring the magnetic fields and hence distribution of current in an array. An imaging Faraday system utilizes a short laser pulse to make estimates of the current distribution in the precursor column formed on axis before implosion. In a second system, a rod of high Verdet constant glass is placed close to the wires of an array and the polarization of a cw laser passing through the rod is monitored to examine the variance of current with time

  14. Comparison of genetic-algorithm and emissivity-ratio analyses of image data from OMEGA implosion cores.

    Science.gov (United States)

    Nagayama, T; Mancini, R C; Florido, R; Tommasini, R; Koch, J A; Delettrez, J A; Regan, S P; Smalyuk, V A; Welser-Sherrill, L A; Golovkin, I E

    2008-10-01

    Detailed analysis of x-ray narrow-band images from argon-doped deuterium-filled inertial confinement fusion implosion experiments yields information about the temperature spatial structure in the core at the collapse of the implosion. We discuss the analysis of direct-drive implosion experiments at OMEGA, in which multiple narrow-band images were recorded with a multimonochromatic x-ray imaging instrument. The temperature spatial structure is investigated by using the sensitivity of the Ly beta/He beta line emissivity ratio to the temperature. Three analysis methods that consider the argon He beta and Ly beta image data are discussed and the results compared. The methods are based on a ratio of image intensities, ratio of Abel-inverted emissivities, and a search and reconstruction technique driven by a Pareto genetic algorithm. PMID:19044576

  15. The art of implosions has impacted the success of three decontamination and decommissioning projects at Fernald

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) at the Fernald Environmental Management Project (FEMP), near Cincinnati, Ohio, has successfully impacted the safety, cost and schedule goals of the Decontamination and Dismantling (D ampersand D) Program by using the art of implosions. An implosion is the act of bringing a structure down in a well planned and directed manner using explosive materials. Three major structures in three separate projects were imploded using this well known commercial technology. Safety is, and will always be, the major consideration with each of the projects. As each project succeeded another, the work process used new and improved methods to lower the risk to the environment, provide a safer workplace by reducing the exposure of high risk work and reducing the spread of lead, asbestos and radioactive materials. The time frame for dismantlement of the steel structures was greatly improved, thus reducing the total project cost. The lessons learned were incorporated from one project to another, to continually improve the work process. A number of alternatives were considered for the removal of the structures, seven, four and three stories in height. The subcontractor and its demolition sub-tier contractor worked in a fixed price lump sum contract environment. While skeptical at first, the subcontractor realized the benefits of the technology, a win-win situation for all participants. The overall planning of each of the events was tied to the needs of the client (DOE), the stakeholders and the community surrounding the site, and the continuing progress at the Fernald site. The recording and application of several key lessons learned in the sequence of implosions, will be the key issues of interest in this paper. Each project offered interesting opportunities for contingency planning, coordination, safety culture adjustments, and high regard for the protection of surrounding structures

  16. Charged-particle spectroscopy for diagnosing shock ρR and strength in NIF implosions.

    Science.gov (United States)

    Zylstra, A B; Frenje, J A; Séguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M Gatu; Casey, D T; Sinenian, N; Manuel, M J-E; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G W; Dewald, E; Döppner, T; Edwards, M J; Glenzer, S; Hicks, D G; Landen, O L; London, R; Mackinnon, A; Meezan, N; Prasad, R R; Ralph, J; Richardson, M; Rygg, J R; Sepke, S; Weber, S; Zacharias, R; Moses, E; Kilkenny, J; Nikroo, A; Sangster, T C; Glebov, V; Stoeckl, C; Olson, R; Leeper, R J; Kline, J; Kyrala, G; Wilson, D

    2012-10-01

    The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign diagnostic. The WRF measures the spectrum of protons from D-(3)He reactions in tuning-campaign implosions containing D and (3)He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total ρR through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

  17. Non-LTE considerations in spectral diagnostics of thermal transport and implosion experiments

    International Nuclear Information System (INIS)

    Recent thermal-transport and target-implosion experiments have used the emission of radiation from highly-ionized ions to signal the advance of laser-driven heat fronts and to mark the trajectories and stagnation points of imploding shells. We examine the results of such experiments with particular attention given to non-LTE effects of non-Maxwellian electrons and of finite ionization times on the populations of signature-emitting atomic species and on the formation of signature spectra and x-ray images in these experiments

  18. Explicit Dynamic Finite Element Method for Predicting Implosion/Explosion Induced Failure of Shell Structures

    Directory of Open Access Journals (Sweden)

    Jeong-Hoon Song

    2013-01-01

    Full Text Available A simplified implementation of the conventional extended finite element method (XFEM for dynamic fracture in thin shells is presented. Though this implementation uses the same linear combination of the conventional XFEM, it allows for considerable simplifications of the discontinuous displacement and velocity fields in shell finite elements. The proposed method is implemented for the discrete Kirchhoff triangular (DKT shell element, which is one of the most popular shell elements in engineering analysis. Numerical examples for dynamic failure of shells under impulsive loads including implosion and explosion are presented to demonstrate the effectiveness and robustness of the method.

  19. Scalings of implosion experiment for high neutron yield

    International Nuclear Information System (INIS)

    A series of experiments focused on high neutron yield has been done with Gekko-XII green laser system. DT neutron yield of 1013, pellet gain 0.2 %, and coupling efficiency 5.5 % have been achieved. Based on the experimental data for more than 70 shots, the scaling laws of the neutron yield and the related physical quantities have been studied. The comparison of the experimental neutron yield with that obtained by one-dimensional fluid code has led us to a conclusion that most of the neutron yield produced in the stagnation phase is not observed in the experiment because of fuel-pusher mixing possibly induced by the Rayleigh-Taylor instability. A DT core gain of 5 % has also been obtained. The experimental data plotted in the ρR-Ti diagram indicate that for igniting the fuel, the ion temperature is sufficiently high, while the ρR is less by two orders of magnitude than the required value. (author)

  20. Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

    Science.gov (United States)

    Li, Yongsheng; Gu, Jianfa; Wu, Changshu; Song, Peng; Dai, Zhensheng; Li, Shuanggui; Li, Xin; Kang, Dongguo; Gu, Peijun; Zheng, Wudi; Zou, Shiyang; Ding, Yongkun; Lan, Ke; Ye, Wenhua; Zhang, Weiyan

    2016-07-01

    Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting "tent." Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates the ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.

  1. Copper Wire Arrays at the 1 MA Zebra Facility

    Science.gov (United States)

    Coverdale, C. A.; Jones, B.; Ampleford, D. J.; Deeney, C.; Lepell, P. D.; Safronova, A. S.; Kantsyrev, V. L.; Ouart, N.; Ivanov, V. V.

    2006-10-01

    Experiments to study the implosion dynamics and radiation characteristics of copper z-pinches have been fielded at the 1 MA Zebra facility. At Zebra, load diameters ranged from 8mm to 16mm, with 6 to 14 wires, and load masses of 80 to 200 μg. All arrays utilized 10 micron diameter wire. The impact of initial load mass and initial load diameter on the precursor and the stagnated plasma has been evaluated through spectroscopy, shadowgraphy, and fluence measurements. Plasma parameters have been extracted from modeling of the time-integrated L-shell spectra to study temperature and density variations as a function of spatial position and initial load configuration. Comparisons will be made with harder x-ray spectra and pinhole images to identify regions of highest temperature and density. Shadowgraphy has been fielded to study the formation of the precursor and the main implosion; significant structure is observed. Substantial radiation is observed from the precursor, with variations in the precursor associated with initial load configuration. *Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  2. Cryogenic Implosion Performance Using High-Purity Deuterium-Tritium Fuel

    Science.gov (United States)

    Sangster, T. C.; Goncharov, V. N.; Radha, P. B.; Earley, R.; Epstein, R.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu.; Hu, S. X.; Igumenshchev, I. V.; Marshall, F. J.; McKenty, P. W.; Shmayda, W. T.; Shoup, M. J., III; Michel, D. T.; Stoeckl, C.; Seka, W.; Frenje, J. A.; Gatu Johnson, M.

    2014-10-01

    Demonstrating hydrodynamic equivalence between symmetric implosions on OMEGA and National Ignition Facility ignition designs will require a number of facility enhancements that include dynamic bandwidth reduction, a set of higher-order super-Gaussian phase plates, high-spatial-resolution gated-core imaging, high-bandwidth neutron burnwidth measurements, improved power balance, and contaminant-free deuterium-tritium (DT) fuel. The historic DT fuel supply was contaminated with ~6 atm% of 1H, leading to significant fractionation of the fuel during the layering process (the triple points of H:D and H:T are significantly colder than DD, DT, and TT). The fractionation leads to a drop in the potential yield because the D and T number densities are lower in the void than they would be with a pure-DT mixture). An isotope separation system has been developed to remove the 1H from the DT fuel supply. This talk will discuss the first results with the purified fuel, conclusions from recent implosions to test cross-beam energy transfer mitigation, and the status of the remaining facility enhancements. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  3. X-ray drive of beryllium capsule implosions at the National Ignition Facility

    Science.gov (United States)

    Wilson, D. C.; Yi, S. A.; Simakov, A. N.; Kline, J. L.; Kyrala, G. A.; Dewald, E. L.; Tommasini, R.; Ralph, J. E.; Olson, R. E.; Strozzi, D. J.; Celliers, P. M.; Schneider, M. B.; MacPhee, A. G.; Zylstra, A. B.; Callahan, D. A.; Hurricane, O. A.; Milovich, J. L.; Hinkel, D. E.; Rygg, J. R.; Rinderknecht, H. G.; Sio, H.; Perry, T. S.; Batha, S.

    2016-05-01

    National Ignition Facility experiments with beryllium capsules have followed a path begun with “high-foot” plastic capsule implosions. Three shock timing keyhole targets, one symmetry capsule, a streaked backlit capsule, and a 2D backlit capsule were fielded before the DT layered shot. After backscatter subtraction, laser drive degradation is needed to match observed X-ray drives. VISAR measurements determined drive degradation for the picket, trough, and second pulse. Time dependence of the total Dante flux reflects degradation of the of the third laser pulse. The same drive degradation that matches Dante data for three beryllium shots matches Dante and bangtimes for plastic shots N130501 and N130812. In the picket of both Be and CH hohlraums, calculations over-estimate the x-ray flux > 1.8 keV by ∼100X, while calculating the total flux correctly. In beryllium calculations these X-rays cause an early expansion of the beryllium/fuel interface at ∼3 km/s. VISAR measurements gave only ∼0.3 km/s. The X-ray drive on the Be DT capsule was further degraded by an unplanned decrease of 9% in the total picket flux. This small change caused the fuel adiabat to rise from 1.8 to 2.3. The first NIF beryllium DT implosion achieved 29% of calculated yield, compared to CH capsules with 68% and 21%.

  4. Numerical Simulation of 2-D Radiation-Drive Ignition Implosion Process

    Institute of Scientific and Technical Information of China (English)

    YONG Heng; SONG Peng; ZHAI Chuan-Lei; KANG Dong-Guo; GU Jian-Fa; HANG Xu-Deng; GU Pei-Jun

    2013-01-01

    A Lagrangian compatible radiation hydrodynamic algorithm and the nuclear dynamics computing module are developed and implemented in the LARED Integration code,which is a radiation hydrodynamic code based on the 2-D cylindrical coordinates for the numerical simulation of the indirect-drive Inertial Confined Fusion.A number of 1-D and 2-D ignition implosion numerical simulations by using the improved LARED Integration code (ILARED) are presented which show that the 1-D numerical results are consistent with those computed by the 1-D radiation hydrodynamic code RDMG,while the simulation results of the 2-D low-mode radiative asymmetry and hydrodynamic instability growth,according to the physical analysis and anticipation,are satisfactory.The capsules driven by the sources from SGH experiments are also simulated by ILARED,and the fuel shapes agree well with the experimental results.The numerical simulations demonstrate that ILARED can be used in the simulation of the 1-D and 2-D ignition capsule implosion using the multi-group diffusion model for radiation.

  5. New tuning method of the low-mode asymmetry for ignition capsule implosions

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Jianfa, E-mail: gu-jianfa@iapcm.ac.cn; Dai, Zhensheng; Zou, Shiyang; Song, Peng; Ye, Wenhua; Zheng, Wudi; Gu, Peijun [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2015-12-15

    In the deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility, the hot spot and the surrounding main fuel layer show obvious P2 asymmetries. This may be caused by the large positive P2 radiation flux asymmetry during the peak pulse resulting form the poor propagation of the inner laser beam in the gas-filled hohlraum. The symmetry evolution of ignition capsule implosions is investigated by applying P2 radiation flux asymmetries during different time intervals. A series of two-dimensional simulation results show that a positive P2 flux asymmetry during the peak pulse results in a positive P2 shell ρR asymmetry; while an early time positive P2 flux asymmetry causes a negative P2 in the fuel ρR shape. The opposite evolution behavior of shell ρR asymmetry is used to develop a new tuning method to correct the radiation flux asymmetry during the peak pulse by adding a compensating same-phased P2 drive asymmetry during the early time. The significant improvements of the shell ρR symmetry, hot spot shape, hot spot internal energy, and neutron yield indicate that the tuning method is quite effective. The similar tuning method can also be used to control the early time drive asymmetries.

  6. Hohlraum-Driven Ignition-Like Double-Shell Implosion Experiments on Omega: Analysis and Interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, P; Robey, H F; Park, H-S; Tipton, R E; Turner, R E; Milovich, J; Rowley, D; Hibbard, R; Louis, H; Wallace, R; Garbett, W; Dunne, A M; Varnum, W S; Watt, R G; Wilson, D C

    2003-08-22

    An experimental campaign to study hohlraum-driven ignition-like double-shell target performance using the Omega laser facility has begun. These targets are intended to incorporate as many ignition-like properties of the proposed National Ignition Facility (NIF) double-shell ignition design [1,2] as possible, given the energy constraints of the Omega laser. In particular, this latest generation of Omega double-shells is nominally predicted to produce over 99% of the (clean) DD neutron yield from the compressional or stagnation phase of the implosion as required in the NIF ignition design. By contrast, previous double-shell experience on Omega [3] was restricted to cases where a significant fraction of the observed neutron yield was produced during the earlier shock convergence phase where the effects of mix are deemed negligibly small. These new targets are specifically designed to have optimized fall-line behavior for mitigating the effects of pusher-fuel mix after deceleration onset and, thereby, providing maximum neutron yield from the stagnation phase. Experimental results from this recent Omega ignition-like double-shell implosion campaign show favorable agreement with two-dimensional integrated hohlraum simulation studies when enhanced (gold) hohlraum M-band (2-5 keV) radiation is included at a level consistent with observations.

  7. Measurements of the Fuel Distribution in Cryogenic D-T Direct-Drive Implosions

    Science.gov (United States)

    Forrest, Chad J.

    In direct-drive inertial confinement fusion (ICF) experiments, a capsule filled with a mixture of deuterium and tritium ice at cryogenic temperature is irradiated by a symmetric arrangements of laser beams to compress and heat the fuel to conditions required for thermonuclear reactions. The areal density (rhoR) of the compressed fuel assembly in a cryogenic implosion is one of the fundamental parameters required to assess the target performance. The rhoR measurements presented here are achieved by measuring the complex neutron energy spectrum resulting from primary and secondary nuclear reactions within the compressed fuel assembly. Advances in neutron time-of-flight diagnostics have made it possible to infer the neutron fraction that elastically scatters off the tritons in the compressed fuel in the energy range from 3.5 -5.5 MeV which is directly proportional to the areal density. In these OMEGA cryogenic campaigns from January 2013 to August 2014, measured low-mode modulations show good agreement with Monte Carlo simulations. Deviations up to 40% in the cold-fuel distribution from spherical symmetry have been inferred from the scattered neutron spectrum. Understanding the mechanism for anisotropic areal density measurements is crucial to improve hydrodynamically equivalent ignition-relevant direct-drive cryogenic implosions on OMEGA.

  8. Capsule implosion optimization during the indirect-drive National Ignition Campaign

    International Nuclear Information System (INIS)

    Capsule performance optimization campaigns will be conducted at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition. The campaigns will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models using a variety of ignition capsule surrogates before proceeding to cryogenic-layered implosions and ignition experiments. The quantitative goals and technique options and down selections for the tuning campaigns are first explained. The computationally derived sensitivities to key laser and target parameters are compared to simple analytic models to gain further insight into the physics of the tuning techniques. The results of the validation of the tuning techniques at the OMEGA facility [J. M. Soures et al., Phys. Plasmas 3, 2108 (1996)] under scaled hohlraum and capsule conditions relevant to the ignition design are shown to meet the required sensitivity and accuracy. A roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget. Finally, we show how the tuning precision will be improved after a number of shots and iterations to meet an acceptable level of residual uncertainty.

  9. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    International Nuclear Information System (INIS)

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction

  10. Bolometric Arrays for Millimeter Wavelengths

    Science.gov (United States)

    Castillo, E.; Serrano, A.; Torres-Jácome, A.

    2009-11-01

    During last years, semiconductor bolometers using thin films have been developed at INAOE, specifically boron-doped hydrogenated amorphous silicon films. The characteristics shown by these devices made them attractive to be used in astronomical instrumentation, mainly in two-dimentional arrays. These detector arrays used at the Large Millimeter Telescope will make possible to obtain astronomical images in millimeter and sub-millimeter wavelengths. With this in mind, we are developing a method to produce, with enough reliability, bolometer arrays at INAOE. Until now, silicon nitride diaphragm arrays, useful as radiation absorbers, have succesfully been obtained. Sizes going from one to four millimeter by element in a consistent way; however we have not tested thermometers and metallic contact deposition yet. At the same time, we are working on two possible configurations for the readout electronics; one of them using commercial components while the other will be an integrated circuit specifically designed for this application. Both versions will work below 77K.

  11. Using multiple secondary fusion products to evaluate fuel ρR, electron temperature, and mix in deuterium-filled implosions at the NIF

    Energy Technology Data Exchange (ETDEWEB)

    Rinderknecht, H. G., E-mail: hgr@mit.edu; Rosenberg, M. J.; Zylstra, A. B.; Lahmann, B.; Séguin, F. H.; Frenje, J. A.; Li, C. K.; Gatu Johnson, M.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Berzak Hopkins, L. F.; Caggiano, J. A.; Divol, L.; Hartouni, E. P.; Hatarik, R.; Hatchett, S. P.; Le Pape, S.; Mackinnon, A. J.; McNaney, J. M.; Meezan, N. B.; Moran, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2015-08-15

    In deuterium-filled inertial confinement fusion implosions, the secondary fusion processes D({sup 3}He,p){sup 4}He and D(T,n){sup 4}He occur, as the primary fusion products {sup 3}He and T react in flight with thermal deuterons. In implosions with moderate fuel areal density (∼5–100 mg/cm{sup 2}), the secondary D-{sup 3}He reaction saturates, while the D-T reaction does not, and the combined information from these secondary products is used to constrain both the areal density and either the plasma electron temperature or changes in the composition due to mix of shell material into the fuel. The underlying theory of this technique is developed and applied to three classes of implosions on the National Ignition Facility: direct-drive exploding pushers, indirect-drive 1-shock and 2-shock implosions, and polar direct-drive implosions. In the 1- and 2-shock implosions, the electron temperature is inferred to be 0.65 times and 0.33 times the burn-averaged ion temperature, respectively. The inferred mixed mass in the polar direct-drive implosions is in agreement with measurements using alternative techniques.

  12. Recent experimental results on ICF target implosions by Z-pinch radiation sources and their relevance to ICF ignition studies.

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, James E.; Chandler, Gordon Andrew; Vesey, Roger Alan; Hanson, David Lester; Olson, Craig Lee; Nash, Thomas J.; Matzen, Maurice Keith; Ruiz, Carlos L.; Porter, John Larry, Jr.; Cuneo, Michael Edward; Varnum, William S.; Bennett, Guy R. (K-tech Corporation, Albuquerque, NM); Cooper, Gary Wayne; Schroen, Diana Grace (Schafer Gorp., Livermore, CA); Slutz, Stephen A.; MacFarlane, Joseph John (Prism Computational Sciences, Madison, WI); Leeper, Ramon Joe; Golovkin, I. E. (Prism Computational Sciences, Madison, WI); Mehlhorn, Thomas Alan; Mancini, Roberto Claudio (University of Nevada, Reno, NV)

    2003-07-01

    Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a {approx}220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6 {+-} 1.3) x 10{sup 10}. Argon spectra confirm a hot fuel with Te {approx} 1 keV and n{sub e} {approx} (1-2) x 10{sup 23} cm{sup -3}. Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a {approx}70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P{sub 2} radiation asymmetries to {+-}2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL.

  13. Recent experimental results on ICF target implosions by Z-pinch radiation sources and their relevance to ICF ignition studies

    International Nuclear Information System (INIS)

    Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6 ± 1.3) x 1010. Argon spectra confirm a hot fuel with Te ∼ 1 keV and ne ∼ (1-2) x 1023 cm-3. Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P2 radiation asymmetries to ±2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL.

  14. First Experiments with Planar Wire Arrays on U Michigan's Linear Transformer Driver

    Science.gov (United States)

    Safronova, A. S.; Kantsyrev, V. L.; Weller, M. E.; Shrestha, I. K.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M.; Stafford, A.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Jordan, N. M.; Gilgenbach, R. M.

    2014-10-01

    For petawatt-class Z-pinch accelerators, a Linear Transformer Driver (LTD)-driven accelerator promises to be (at a given pinch current and implosion time) more efficient than the conventionally used Marx-driven accelerator. Because there exists almost no data on how wire arrays radiate on LTD-based machines in the USA, it is very important to perform radiation and plasma physics studies on this new type of generator. We report on the first outcome of the new partnership with University of Michigan (UM), which resulted in successful UNR-UM experiments on the low-impedance MAIZE generator with planar wire arrays (PWA). PWA is a novel wire array load that was introduced and tested in detail on high-impedance Zebra at UNR during the last years and found to be the most efficient radiator. Implosion of Al Double PWAs of different configurations were achieved on MAIZE, observed with a set of various diagnostics which include x-ray diode detectors, x-ray spectroscopy and imaging, and shadowgraphy. Al and Mg plasmas of more than 450 eV were studied in detail. Research supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. G. Patel and A. M. Steiner supported by Sandia National Laboratories. D. A. Yager-Elorriaga supported by NSF GF.

  15. Beam combining of quantum cascade laser arrays.

    Science.gov (United States)

    Lee, Benjamin G; Kansky, Jan; Goyal, Anish K; Pflügl, Christian; Diehl, Laurent; Belkin, Mikhail A; Sanchez, Antonio; Capasso, Federico A

    2009-08-31

    Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.

  16. Hot spot formation and stagnation properties in simulations of direct-drive NIF implosions

    Science.gov (United States)

    Schmitt, Andrew J.; Obenschain, Stephen P.

    2016-05-01

    We investigate different proposed methods of increasing the hot spot energy and radius in inertial confinement fusion implosions. In particular, shock mistiming (preferentially heating the inner edge of the target's fuel) and increasing the initial vapor gas density are investigated as possible control mechanisms. We find that only the latter is effective in substantially increasing the hot spot energy and dimensions while achieving ignition. In all cases an increase in the hot spot energy is accompanied by a decrease in the hot spot energy density (pressure) and both the yield and the gain of the target drop substantially. 2D simulations of increased vapor density targets predict an increase in the robustness of the target with respect to surface perturbations but are accompanied by significant yield degradation.

  17. Performance and Mix Measurements of Indirect Drive Cu-Doped Be Implosions.

    Science.gov (United States)

    Casey, D T; Woods, D T; Smalyuk, V A; Hurricane, O A; Glebov, V Y; Stoeckl, C; Theobald, W; Wallace, R; Nikroo, A; Schoff, M; Shuldberg, C; Wu, K J; Frenje, J A; Landen, O L; Remington, B A; Glendinning, G

    2015-05-22

    The ablator couples energy between the driver and fusion fuel in inertial confinement fusion (ICF). Because of its low opacity, high solid density, and material properties, beryllium has long been considered an ideal ablator for ICF ignition experiments at the National Ignition Facility. We report here the first indirect drive Be implosions driven with shaped laser pulses and diagnosed with fusion yield at the OMEGA laser. The results show good performance with an average DD neutron yield of ∼2×10^{9} at a convergence ratio of R_{0}/R∼10 and little impact due to the growth of hydrodynamic instabilities and mix. In addition, the effect of adding an inner liner of W between the Be and DD is demonstrated. PMID:26047234

  18. Performance and Mix Measurements of Indirect Drive Cu-Doped Be Implosions

    Energy Technology Data Exchange (ETDEWEB)

    Casey, D.  T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Woods, D. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Smalyuk, V. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hurricane, O.  A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glebov, V.  Y. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Stoeckl, C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Theobald, W. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Wallace, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nikroo, A. [General Atomics, San Diego, CA (United States); Schoff, M. [General Atomics, San Diego, CA (United States); Shuldberg, C. [General Atomics, San Diego, CA (United States); Wu, K. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frenje, J.  A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Landen, O.  L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Remington, B.  A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glendinning, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-19

    The ablator couples energy between the driver and fusion fuel in inertial confinement fusion (ICF). Because of its low opacity, high solid density, and material properties, beryllium has long been considered an ideal ablator for ICF ignition experiments at the National Ignition Facility. We report here the first indirect drive Be implosions driven with shaped laser pulses and diagnosed with fusion yield at the OMEGA laser. The results show good performance with an average DD neutron yield of ~2 × 10⁹ at a convergence ratio of R₀/R ~ 10 and little impact due to the growth of hydrodynamic instabilities and mix. In addition, the effect of adding an inner liner of W between the Be and DD is demonstrated.

  19. A hybrid model for coupling kinetic corrections of fusion reactivity to hydrodynamic implosion simulations

    Science.gov (United States)

    Tang, Xian-Zhu; McDevitt, C. J.; Guo, Zehua; Berk, H. L.

    2014-03-01

    Inertial confinement fusion requires an imploded target in which a central hot spot is surrounded by a cold and dense pusher. The hot spot/pusher interface can take complicated shape in three dimensions due to hydrodynamic mix. It is also a transition region where the Knudsen and inverse Knudsen layer effect can significantly modify the fusion reactivity in comparison with the commonly used value evaluated with background Maxwellians. Here, we describe a hybrid model that couples the kinetic correction of fusion reactivity to global hydrodynamic implosion simulations. The key ingredient is a non-perturbative treatment of the tail ions in the interface region where the Gamow ion Knudsen number approaches or surpasses order unity. The accuracy of the coupling scheme is controlled by the precise criteria for matching the non-perturbative kinetic model to perturbative solutions in both configuration space and velocity space.

  20. Wobblers and Rayleigh-Taylor instability mitigation in HIF target implosion

    Science.gov (United States)

    Kawata, S.; Kurosaki, T.; Noguchi, K.; Suzuki, T.; Koseki, S.; Barada, D.; Ma, Y. Y.; Ogoyski, A. I.; Barnard, J. J.; Logan, B. G.

    2014-01-01

    A few percent wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) by a spiraling beam axis motion in the paper. The wobbling heavy ion beam (HIB) illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In wobbling the HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs' illumination nonuniformity and also the mitigation of the Rayleigh-Taylor instability. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be from several 100 MHz to 1 GHz. Three-dimensional HIBs illumination computations presented here show that the few percent wobbling HIBs illumination nonuniformity oscillates successfully with the same wobbling HIBs frequency.

  1. Wobblers and Rayleigh–Taylor instability mitigation in HIF target implosion

    Energy Technology Data Exchange (ETDEWEB)

    Kawata, S., E-mail: kwt@cc.utsunomiya-u.ac.jp [Utsunomiya University, 7-1-2 Yohtoh, Utsunomiya 321-8585 (Japan); Kurosaki, T.; Noguchi, K.; Suzuki, T.; Koseki, S.; Barada, D.; Ma, Y.Y. [Utsunomiya University, 7-1-2 Yohtoh, Utsunomiya 321-8585 (Japan); Ogoyski, A.I. [Varna Technical University, Varna 9010 (Bulgaria); Barnard, J.J.; Logan, B.G. [Lawrence Berkeley National Laboratory for Heavy Ion Fusion, Berkeley, CA 94720 (United States); Virtual National Laboratory for Heavy Ion Fusion, Berkeley, CA 94720 (United States)

    2014-01-01

    A few percent wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) by a spiraling beam axis motion in the paper. The wobbling heavy ion beam (HIB) illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In wobbling the HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs' illumination nonuniformity and also the mitigation of the Rayleigh–Taylor instability. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be from several 100 MHz to 1 GHz. Three-dimensional HIBs illumination computations presented here show that the few percent wobbling HIBs illumination nonuniformity oscillates successfully with the same wobbling HIBs frequency.

  2. Symmetric inertial confinement fusion implosions at ultra-high laser energies

    International Nuclear Information System (INIS)

    The first indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 MJ. 192 simultaneously fired laser beams heat ignition hohlraums to radiation temperatures of 3.3 million Kelvin compressing 1.8-millimeter capsules by the soft x rays produced by the hohlraum. Self-generated plasma-optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum producing symmetric x-ray drive as inferred from capsule self-emission measurements. These experiments indicate conditions suitable for compressing deuterium-tritium filled capsules with the goal to achieve burning fusion plasmas and energy gain in the laboratory.

  3. Interactive tools designed to study mix in inertial confinement fusion implosions

    Energy Technology Data Exchange (ETDEWEB)

    Welser-sherrill, Leslie [Los Alamos National Laboratory; Cooley, James H [Los Alamos National Laboratory; Wilson, Doug C [Los Alamos National Laboratory

    2008-01-01

    Graphical user interface tools have been built in IDL to study mix in inertial confinement fusion (ICF) implosion cores. FLAME (Fall-Line Analysis Mix Evaluator), a code which investigates yield degradation due to mix , was designed to post-process 1D hydrodynamic simulation output by implementing a variety of mix models. Three of these mix models are based on the physics of the fall-line. In addition, mixing data from other sources can be incorporated into the yield degradation analysis. Two independent tools called HAME (Haan Analysis Mix Evaluator) and YAME (Youngs Analysis Mix Evaluator) were developed to calculate the spatial extent of the mix region according to the Haan saturation model and Youngs' phenomenological model, respectively. FLAME facilitates a direct comparison to experimental data. The FLAME, HAME, and YAME interfaces are user-friendly, flexible, and platform-independent.

  4. Celui qui implose dans le vacuum de la difficulté de survivre dans le vacuum

    Directory of Open Access Journals (Sweden)

    Gaston Tremblay

    2004-03-01

    Full Text Available Le vacuum dont nous parlons découle directement de l’implosion du Canada français, c’est-à-dire du mouvement de repli qui, à la fin des années soixante, amène les Canadiens-Français à délimiter pour la première fois leurs frontières nationales. C’est en quelque sorte une conversion au réel, aussi bien pour les Québécois qui tentent alors de prendre possession de leur territoire, que pour les Franco-Ontariens qui doivent faire le deuil de leurs institutions nationales.

  5. Understanding the effects of laser imprint on plastic-target implosions on OMEGA

    Science.gov (United States)

    Hu, S. X.; Michel, D. T.; Davis, A. K.; Betti, R.; Radha, P. B.; Campbell, E. M.; Froula, D. H.; Stoeckl, C.

    2016-10-01

    Understanding the effects of laser imprint on target performance is critical to the success of direct-drive inertial confinement fusion. Directly measuring the disruption caused by laser imprints to the imploding shell and hot-spot formation, in comparison with multidimensional radiation-hydrodynamic simulations, can provide a clear picture of how laser nonuniformities cause target performance to degrade. With the recently developed x-ray self-emission imaging technique and the state-of-the-art physics models recently implemented in the two-dimensional hydrocode DRACO, a systematic study of laser-imprint effects on warm target implosions on OMEGA has been performed using both experimental results and simulations. By varying the laser-picket intensity, the imploding shells were set at different adiabats (from α = 2 to α = 6). As the shell adiabats decreased, it was observed that (1) the measured shell thickness at the time the hot spot lit up became larger than the uniform one-dimensional (1-D) predictions; (2) the hot-spot core emitted earlier than the corresponding 1-D predictions; (3) the measured neutron yield first increased then decreased as the shell adiabat α was reduced; and (4) the hot-spot size reduced as α decreased for cases where SSD (smoothing by spectral dispersion) was on but became larger for low-α shots in cases where SSD was off. Most of these experimental observations are well reproduced by DRACO simulations with laser imprints including modes up to λmax = 200. These studies identify the importance of laser imprint as the major source of degrading target performance for OMEGA implosions of adiabat α ≤ 3. Mitigating laser imprints is required to improve low-α target performance.

  6. First results of radiation-driven, layered deuterium-tritium implosions with a 3-shock adiabat-shaped drive at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Jones, O. S.; Milovich, J. L.; Bachmann, B.; Baker, K. L.; Berzak Hopkins, L. F.; Bond, E.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Hurricane, O. A.; Jancaitis, K. S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2015-08-15

    Radiation-driven, layered deuterium-tritium plastic capsule implosions were carried out using a new, 3-shock “adiabat-shaped” drive on the National Ignition Facility. The purpose of adiabat shaping is to use a stronger first shock, reducing hydrodynamic instability growth in the ablator. The shock can decay before reaching the deuterium-tritium fuel leaving it on a low adiabat and allowing higher fuel compression. The fuel areal density was improved by ∼25% with this new drive compared to similar “high-foot” implosions, while neutron yield was improved by more than 4 times, compared to “low-foot” implosions driven at the same compression and implosion velocity.

  7. Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF

    Science.gov (United States)

    Ma, T.; Chen, H.; Patel, P. K.; Schneider, M. B.; Barrios, M. A.; Casey, D. T.; Chung, H.-K.; Hammel, B. A.; Berzak Hopkins, L. F.; Jarrott, L. C.; Khan, S. F.; Lahmann, B.; Nora, R.; Rosenberg, M. J.; Pak, A.; Regan, S. P.; Scott, H. A.; Sio, H.; Spears, B. K.; Weber, C. R.

    2016-11-01

    The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.

  8. First Measurements of Fuel-Ablator Interface Instability Growth in Inertial Confinement Fusion Implosions on the National Ignition Facility

    Science.gov (United States)

    Weber, C. R.; Döppner, T.; Casey, D. T.; Bunn, T. L.; Carlson, L. C.; Dylla-Spears, R. J.; Kozioziemski, B. J.; MacPhee, A. G.; Nikroo, A.; Robey, H. F.; Sater, J. D.; Smalyuk, V. A.

    2016-08-01

    Direct measurements of hydrodynamic instability growth at the fuel-ablator interface in inertial confinement fusion (ICF) implosions are reported for the first time. These experiments investigate one of the degradation mechanisms behind the lower-than-expected performance of early ICF implosions on the National Ignition Facility. Face-on x-ray radiography is used to measure instability growth occurring between the deuterium-tritium fuel and the plastic ablator from well-characterized perturbations. This growth starts in two ways through separate experiments—either from a preimposed interface modulation or from ablation front feedthrough. These experiments are consistent with analytic modeling and radiation-hydrodynamic simulations, which say that a moderately unstable Atwood number and convergence effects are causing in-flight perturbation growth at the interface. The analysis suggests that feedthrough from outersurface perturbations dominates the interface perturbation growth at mode 60.

  9. Measurement of high-pressure shock waves in cryogenic deuterium-tritium ice layered capsule implosions on NIF.

    Science.gov (United States)

    Robey, H F; Moody, J D; Celliers, P M; Ross, J S; Ralph, J; Le Pape, S; Berzak Hopkins, L; Parham, T; Sater, J; Mapoles, E R; Holunga, D M; Walters, C F; Haid, B J; Kozioziemski, B J; Dylla-Spears, R J; Krauter, K G; Frieders, G; Ross, G; Bowers, M W; Strozzi, D J; Yoxall, B E; Hamza, A V; Dzenitis, B; Bhandarkar, S D; Young, B; Van Wonterghem, B M; Atherton, L J; Landen, O L; Edwards, M J; Boehly, T R

    2013-08-01

    The first measurements of multiple, high-pressure shock waves in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these shocks must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of shock timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique.

  10. Effects of the irradiation of a finite number of laser beams on the implosion of a cone-guided target

    Science.gov (United States)

    Yanagawa, T.; Sakagami, H.; Nagatomo, H.; Sunahara, A.

    2016-03-01

    In direct drive laser fusion, the non-uniformity of the laser absorption on the target surface caused by the irradiation of a finite number of laser beams is a sever problem. GekkoXII laser at Osaka University has twelve laser beams and is irradiated to the target with a dodecahedron orientation, in which the distribution of the laser absorption on the target surface becomes non-uniform. Furthermore, in the case of a cone-guided target, the laser irradiation orientation is more limited. In this paper, we conducted implosion simulations of the cone- guided target based on GekkoXII irradiation orientation and compared the case of using the twelve beams and nine beams where the three beams irradiating the cone region are cut. The implosion simulations were conducted by a three-dimensional pure hydro code.

  11. High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Koch, J. A.; Stewart, R. E.; Beiersdorfer, P.; Shepherd, R.; Schneider, M. B.; Miles, A. R.; Scott, H. A.; Smalyuk, V. A.; Hsing, W. W. [Lawrence Livermore National Laboratory, P.O. Box 808, L-493, Livermore, California 94550 (United States)

    2012-10-15

    Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-{alpha} at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

  12. Neutron Yield and Ion Temperature from DD and DT Fusion in National Ignition Facility High-Foot Implosions

    Science.gov (United States)

    Knauer, J. P.; Gatu Johnson, M.; Frenje, J. A.; Petrasso, R. D.; Caggiano, J. A.; Callahan, D. A.; Casey, D. T.; Cerjan, C. J.; Doeppner, T.; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Hinkel, D. E.; Hurricane, O. A.; Kritcher, A.; Le Pape, S.; Ma, T.; Munro, D. H.; Patel, P. K.; Ralph, J. E.; Sayre, D. B.; Spears, B. K.; Yeamans, C. B.; Kilkenny, J. D.

    2015-11-01

    Simultaneous measures of neutrons emitted from DT fusion implosions are postulated to provide insight into the fuel conditions during neutron emission. Neutron spectral diagnostics of National Ignition Facility ``high-foot'' implosions measure both the DT and DD fusion neutron spectra. Equivalent ion temperature is measured from the width of the DT and DD neutron emission and the respective yields from the peak areas. This work has focused on reasons for differing inferred temperatures from the DT and DD spectra and the yield ratio. Spatial and temporal averages of the DT and DD reactivities as corrections to the homogeneous and static temperature distributions are shown. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  13. Self characterization of a coded aperture array for neutron source imaging

    International Nuclear Information System (INIS)

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF

  14. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

    2015-11-03

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  15. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  16. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Sanford, T.W.L.; Nash, T.J.; Marder, B.M. [and others

    1996-03-01

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, E{sub c}, below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below E{sub c}. These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production.

  17. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    International Nuclear Information System (INIS)

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, Ec, below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below Ec. These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production

  18. Directivity of basic linear arrays

    DEFF Research Database (Denmark)

    Bach, Henning

    1970-01-01

    For a linear uniform array ofnelements, an expression is derived for the directivity as a function of the spacing and the phase constants. The cases of isotropic elements, collinear short dipoles, and parallel short dipoles are included. The formula obtained is discussed in some detail and contour...

  19. Measuring symmetry of implosions in cryogenic Hohlraums at the NIF using gated x-ray detectors (invited).

    Science.gov (United States)

    Kyrala, G A; Dixit, S; Glenzer, S; Kalantar, D; Bradley, D; Izumi, N; Meezan, N; Landen, O L; Callahan, D; Weber, S V; Holder, J P; Glenn, S; Edwards, M J; Bell, P; Kimbrough, J; Koch, J; Prasad, R; Suter, L; Kline, J L; Kilkenny, J

    2010-10-01

    Ignition of imploding inertial confinement capsules requires, among other things, controlling the symmetry with high accuracy and fidelity. We have used gated x-ray imaging, with 10 μm and 70 ps resolution, to detect the x-ray emission from the imploded core of symmetry capsules at the National Ignition Facility. The measurements are used to characterize the time dependent symmetry and the x-ray bang time of the implosion from two orthogonal directions. These measurements were one of the primary diagnostics used to tune the parameters of the laser and Hohlraum to vary the symmetry and x-ray bang time of the implosion of cryogenically cooled ignition scale deuterium/helium filled plastic capsules. Here, we will report on the successful measurements performed with up to 1.2 MJ of laser energy in a fully integrated cryogenics gas-filled ignition-scale Hohlraum and capsule illuminated with 192 smoothed laser beams. We will describe the technique, the accuracy of the technique, and the results of the variation in symmetry with tuning parameters, and explain how that set was used to predictably tune the implosion symmetry as the laser energy, the laser cone wavelength separation, and the Hohlraum size were increased to ignition scales. We will also describe how to apply that technique to cryogenically layered tritium-hydrogen-deuterium capsules.

  20. Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Spears, B K; Glenzer, S; Edwards, M J; Brandon, S; Clark, D; Town, R; Cerjan, C; Dylla-Spears, R; Mapoles, E; Munro, D; Salmonson, J; Sepke, S; Weber, S; Hatchett, S; Haan, S; Springer, P; Moses, E; Mapoles, E; Munro, D; Salmonson, J; Sepke, S

    2011-12-16

    The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.

  1. Development of a polar direct-drive platform for studying inertial confinement fusion implosion mix on the National Ignition Facility

    International Nuclear Information System (INIS)

    Experiments were performed to develop a platform for the simultaneous measurement of mix and its effects on fusion burn. Two polar direct drive implosions of all-plastic capsules were conducted for the first time on the National Ignition Facility (NIF). To measure implosion trajectory and symmetry, area image backlighting of these capsules was also employed for the first time on NIF, an advance over previous 1-D slit imaging experiments, providing detailed symmetry data of the capsules as they imploded. The implosion trajectory and low-mode asymmetry seen in the resultant radiographs agreed with pre-shot predictions even though the 700 kJ drive energy produced laser beam intensities exceeding laser-plasma instability thresholds. Post-shot simulations indicate that the capsule yield was reduced by a factor of two compared to pre-shot predictions owing to as-shot laser drive asymmetries. The pre-shot predictions of bang time agreed within 200 ps with the experimental results. The second shot incorporated a narrow groove encircling the equator of the capsule. A predicted yield reduction factor of three was not observed

  2. Development of Lower Energy Neutron Spectroscopy for Areal Density Measurement in Implosion Experiment at NIF and Omega

    Energy Technology Data Exchange (ETDEWEB)

    Isumi, N; Lerche, R A; Phillips, T W; Schmid, G J; Moran, M J; Sangster, T C

    2001-08-02

    Areal density ({rho}R) is a fundamental parameter that characterizes the performance of an ICF implosion. For high areal densities ({rho}R> 0.1 g/cm{sup 2}), which will be realized in implosion experiments at NIF and LMJ, the target areal density exceeds the stopping range of charged particles and measurements with charged particle spectroscopy will be difficult. In this region, an areal density measurement method using down shifted neutron counting is a promising alternative. The probability of neutron scattering in the imploded plasma is proportional to the areal density of the plasma. The spectrum of neutrons scattered by the specific target nucleus has a characteristic low energy cut off. This enables separate, simultaneous measurements of fuel and pusher {rho}Rs. To apply this concept in implosion experiments, the detector should have extremely large dynamic range. Sufficient signal output for low energy neutrons is also required. A lithium-glass scintillation-fiber plate (LG-SCIFI) is a promising candidate for this application. In this paper we propose a novel technique based on downshifted neutron measurements with a lithium-glass scintillation-fiber plate. The details of instrumentation and background estimation with Monte Carlo calculation are reported.

  3. Measuring symmetry of implosions in cryogenic Hohlraums at the NIF using gated x-ray detectors (invited)

    International Nuclear Information System (INIS)

    Ignition of imploding inertial confinement capsules requires, among other things, controlling the symmetry with high accuracy and fidelity. We have used gated x-ray imaging, with 10 μm and 70 ps resolution, to detect the x-ray emission from the imploded core of symmetry capsules at the National Ignition Facility. The measurements are used to characterize the time dependent symmetry and the x-ray bang time of the implosion from two orthogonal directions. These measurements were one of the primary diagnostics used to tune the parameters of the laser and Hohlraum to vary the symmetry and x-ray bang time of the implosion of cryogenically cooled ignition scale deuterium/helium filled plastic capsules. Here, we will report on the successful measurements performed with up to 1.2 MJ of laser energy in a fully integrated cryogenics gas-filled ignition-scale Hohlraum and capsule illuminated with 192 smoothed laser beams. We will describe the technique, the accuracy of the technique, and the results of the variation in symmetry with tuning parameters, and explain how that set was used to predictably tune the implosion symmetry as the laser energy, the laser cone wavelength separation, and the Hohlraum size were increased to ignition scales. We will also describe how to apply that technique to cryogenically layered tritium-hydrogen-deuterium capsules.

  4. Effects of Low-Order Irradiation Nonuniformity on X-Ray Images of ICF Implosion Experiments on OMEGA

    Science.gov (United States)

    Epstein, R.; Marshall, F. J.; Delettrez, J. A.; McKenty, P. W.; Radha, P. B.; Smalyuk, V. A.

    2003-10-01

    Time-resolved and time-integrated x-ray images of implosion experiments on OMEGA reveal asymmetric hydrodynamic histories of the imploding cores, including the asymmetric arrival and reverberation of the compression shock wave and the asymmetric convergence and expansion of the imploding shell. Implosions driven with irradiation nonuniformity of low harmonic order have been simulated to verify that recent improvements in beam-to-beam power balance, refinements in beam pointing and target positioning, and optimization of beam profiles would produce observed improvements in the image symmetry. Simulations of time-dependent x-ray images clarify how irradiation nonuniformity affects image symmetry and implosion performance. Adding helium to the fill increases the emissivity of the core, allowing the convergence of the compression shock to be visible as well as the impact of the reflected shock on the shell. Simulations have been performed with the hydrodynamic simulation code DRACO, and x-ray images have been simulated with the atomic-physics/radiation-transport postprocessor SPECT3D. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  5. Spherical Horn Array for Wideband Propagation Measurements

    DEFF Research Database (Denmark)

    Franek, Ondrej; Pedersen, Gert Frølund

    2011-01-01

    A spherical array of horn antennas designed to obtain directional channel information and characteristics is introduced. A dual-polarized quad-ridged horn antenna with open flared boundaries and coaxial feeding for the frequency band 600 MHz–6 GHz is used as the element of the array. Matching...

  6. Difference packing arrays and systematic authentication codes

    Institute of Scientific and Technical Information of China (English)

    YIN Jianxing

    2004-01-01

    In this paper, a type of combinatorial design (called difference packing array)is proposed and used to give a construction of systematic authentication codes. Taking advantage of this construction, some new series of systematic authentication codes are obtainable in terms of existing difference packing arrays.

  7. High-foot Implosion Workshop (March 22-24, 2016) Report

    Energy Technology Data Exchange (ETDEWEB)

    Hurricane, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-05-06

    From March 22-24, 2016 at Workshop was held at Lawrence Livermore National Laboratory bringing together international experts in inertial confinement fusion research for the purpose of discussing the results from the ‘high-foot implosion campaign.’ The Workshop topics covered a retrospective of the first two years of experiments, a discussion of our best present understanding of what the data and our models imply, a discussion about remaining mysteries that are not understood at this time, and a discussion of our strategy moving forward. The material herein contains information from published and unpublished sources and is distributed solely for the purposes of this Workshop. Key assessments and conclusions resulting from the Workshop are: “The high foot campaign is extremely well documented and the interested reader is urged to go directly to the peer-reviewed journal literature for details.” – D. Haynes (LANL) “Overall progress in understanding of fuel and hot-spot properties near peak burn is excellent.” – V. Goncharov (LLE) “I would say that given the constraints of using the same hohlraum and similar capsule designs to the National Ignition Campaign, the High Foot Campaign achieved as much as could be expected. Indeed the demonstration of significant alpha particle heating remains a landmark achievement.” – J. Chittenden (Imperial College) “One of the principal points of discussion at the meeting was the importance of the roll over in inferred pressure that occurs with reducing coast time for different ablator thicknesses and the idea of repeating shot N140819 to confirm this. I would be very interested to see a return to the High Foot platform as a way to exercise the improved radiographic capabilities such as the curved crystal imaging system and as a way to examine the hypothesis of ‘burn truncation by aneurism.’ ” – J. Chittenden (Imperial College) “It is clear from the quality of the data presented during this workshop

  8. ANTENNAS ARRAY ADJUST WITH ADAPTIVE NEURONAL SYSTEM

    Directory of Open Access Journals (Sweden)

    A. Padrón

    2004-12-01

    Full Text Available In this work an array failure correction for Linear Antenna Array (LAA is presented. This is carried out by means ofan Adaptive Artificial Neural Network (AANN that adjusts the amplitude and phase at beamforming. Theappropriated corrections are given, when one, or two, or three elements have a failure in the antenna linear array.The AANN corrects the corresponding parameters in the radiation pattern obtained due to the failure, when weknow the coefficients of the array factor (AF. This yields a reduction of side lobe level and some interferencesdisappear.

  9. A direct-drive exploding-pusher implosion as the first step in development of a monoenergetic charged-particle backlighting platform at the National Ignition Facility

    Science.gov (United States)

    Rosenberg, M. J.; Zylstra, A. B.; Séguin, F. H.; Rinderknecht, H. G.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Waugh, C. J.; Sinenian, N.; Li, C. K.; Petrasso, R. D.; LePape, S.; Ma, T.; Mackinnon, A. J.; Rygg, J. R.; Amendt, P. A.; Bellei, C.; Benedetti, L. R.; Berzak Hopkins, L.; Bionta, R. M.; Casey, D. T.; Divol, L.; Edwards, M. J.; Glenn, S.; Glenzer, S. H.; Hicks, D. G.; Kimbrough, J. R.; Landen, O. L.; Lindl, J. D.; MacPhee, A.; McNaney, J. M.; Meezan, N. B.; Moody, J. D.; Moran, M. J.; Park, H.-S.; Pino, J.; Remington, B. A.; Robey, H.; Rosen, M. D.; Wilks, S. C.; Zacharias, R. A.; McKenty, P. W.; Hohenberger, M.; Radha, P. B.; Edgell, D.; Marshall, F. J.; Delettrez, J. A.; Glebov, V. Yu.; Betti, R.; Goncharov, V. N.; Knauer, J. P.; Sangster, T. C.; Herrmann, H. W.; Hoffman, N. M.; Kyrala, G. A.; Leeper, R. J.; Olson, R. E.; Kilkenny, J. D.; Nikroo, A.

    2016-03-01

    A thin-glass-shell, D3He-filled exploding-pusher inertial confinement fusion implosion at the National Ignition Facility (NIF) has been demonstrated as a proton source that serves as a promising first step toward development of a monoenergetic proton, alpha, and triton backlighting platform at the NIF. Among the key measurements, the D3He-proton emission on this experiment (shot N121128) has been well-characterized spectrally, temporally, and in terms of emission isotropy, revealing a highly monoenergetic (ΔE / E ∼ 4 %) and isotropic source (~3% proton fluence variation and ~0.5% proton energy variation). On a similar shot (N130129, with D2 fill), the DD-proton spectrum has been obtained as well, illustrating that monoenergetic protons of multiple energies may be utilized in a single experiment. These results, and experiments on OMEGA, point toward future steps in the development of a precision, monoenergetic proton, alpha, and triton source that can readily be implemented at the NIF for backlighting a broad range of high energy density physics (HEDP) experiments in which fields and flows are manifest, and also utilized for studies of stopping power in warm dense matter and in classical plasmas.

  10. Using m = 0 instability of z-pinch liner for three-dimensional plasma implosion

    Energy Technology Data Exchange (ETDEWEB)

    Alikhanov, S.G.; Bakhtin, V.P.

    1982-03-01

    Previous research has shown that volumetric compression by the magnetic pressure of an imploding Z-pinch liner for nuclear fusion purposes reaches no more than 400 when a cylindrical configuration is used. The authors consider the feasibility of achieving three-dimensional plasma implosion without sacrificing the advantages of shell acceleration by longitudinal current. The evolution of a sausage instability (m = 0) is considered for the case where a liner accelerated by an azimuthal magnetic field compresses a longitudinal magnetic field. It is assumed that the liner is homogeneous in the azimuthal direction and has periodic inhomogeneity in the axial direction. Since the intensity of the magnetic pusher field is inversely proportional to the radius of the liner, pinches are formed in the thinnest sections. Each such pinch generates waves moving in opposite directions toward the parts of the liner that implode most slowly, resulting in nearly closed volumes that are both radially and axially compressed. Under the proper conditions, the compressed cavity develops without axial cumulative jets. 5 references, 1 figure.

  11. Modeling of the merging, liner formation, implosion of hypervelocity plasma jets for the PLX- α project

    Science.gov (United States)

    Cassibry, Jason; Hsu, Scott; Schillo, Kevin; Samulyak, Roman; Stoltz, Peter; Beckwith, Kris

    2015-11-01

    A suite of numerical tools will support the conical and 4 π plasma-liner-formation experiments for the PLX- α project. A new Lagrangian particles (LP) method will provide detailed studies of the merging of plasma jets and plasma-liner formation/convergence. A 3d smooth particle hydrodynamic (SPH) code will simulate conical (up to 9 jets) and 4 π spherical (up to 60 jets) liner formation and implosion. Both LP and SPH will use the same tabular EOS generated by Propaceos, thermal conductivity, optically thin radiation and physical viscosity models. With LP and SPH,the major objectives are to study Mach-number degradation during jet merging, provide RMS amplitude and wave number of the liner nonuniformity at the leading edge, and develop scaling laws for ram pressure and liner uniformity as a function of jet parameters. USIM, a 3D multi-fluid plasma code, will be used to perform 1D and 2D simulations of plasma-jet-driven magneto-inertial fusion (PJMIF) to identify initial conditions in which the ``liner gain'' exceeds unity. A brief overview of the modeling program will be provided. Results from SPH modeling to support the PLX- α experimental design will also be presented, including preliminary ram-pressure scaling and non-uniformity characterization.

  12. Plasma flow switch characterization for the Los Alamos Foil Implosion Project

    International Nuclear Information System (INIS)

    The next system design under consideration for the Los Alamos Foil Implosion Project is projected to deliver tens of mega-amperes of electrical current produced by high-explosive driven flux compression generators on a time scale of about one microsecond to a load foil. The use of such generators, with time scales of order several tenths of a millisecond, leads to considerable pulse shaping problems. Previously it was noted that a commutating switch might serve as an efficient alternative to a closing switch in transferring current from a coaxial transmission line to a cylindrically imploding load. Research at the Air Force Weapons Laboratory (AFWL) has met with considerable success in efficiently transferring currents of order 10 MA to an imploding liner using the plasma flow switch concept (PFS). Besides efficiently transferring current, the plasma flow switch protects the load region from high voltages generated by an opening switch until the current is present to provide magnetic insulation. For these reasons, a PFS is being investigated as the final pulse shaping step in the design. A series of capacitor bank experiments is also being fielded to help investigate physics issues and to benchmark the codes

  13. Three-Dimensional Simulations of the Deceleration Phase of Inertial Fusion Implosions

    Science.gov (United States)

    Woo, K. M.; Betti, R.; Bose, A.; Epstein, R.; Delettrez, J. A.; Anderson, K. S.; Yan, R.; Chang, P.-Y.; Jonathan, D.; Charissis, M.

    2015-11-01

    The three-dimensional radiation-hydrodynamics code DEC3D has been developed to model the deceleration phase of direct-drive inertial confinement fusion implosions. The code uses the approximate Riemann solver on a moving mesh to achieve high resolution near discontinuities. The domain decomposition parallelization strategy is implemented to maintain high computation efficiency for the 3-D calculation through message passing interface. The implicit thermal diffusion is solved by the parallel successive-over-relaxation iteration. Results from 3-D simulations of low-mode Rayleigh-Taylor instability are presented and compared with 2-D results. A systematic comparison of yields, pressures, temperatures, and areal densities between 2-D and 3-D is carried out to determine the additional degradation in target performance caused by the three-dimensionality of the nonuniformities. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

  14. Instability growth seeded by ablator material inhomogeneity in implosions on the National Ignition Facility

    Science.gov (United States)

    Haan, S. W.; Baxamusa, S. H.; Celliers, P. M.; Collins, G. W.; Clark, D. S.; Nikroo, A.; Stadermann, M.; Ho, D. D.; Meezan, N. B.; Smalyuk, V.; Weber, C. R.; Huang, H.; Hoover, D. E.; Nguyen, A. Q. L.; Requieron, W.; Youngblood, K. P.; Kline, J. L.; Simakov, A. N.; Wilson, D. C.; Yi, S. A.

    2015-11-01

    Previous work [Physics of Plasmas 22, 032708 (2015)] on instability growth seeded by oxygen in CH NIF capsules has been extended. Oxygenation of CH can be caused by exposure to X-rays, UV, or visible light, such that irregularities in oxygen are very likely to dominate surface roughness as seed for instabilities in CH NIF implosions. 3D Rayleigh-Taylor experiments show structure that can most plausibly be explained as resulting from this oxygen. Experiments are planned on Omega and NIF to validate this phenomenon, which is still primarily simulation-motivated. Design work and available results for these experiments will be described. The oxygenation of CH might be mitigated by a coating of aluminum oxide on the outside of the shells. Growth is also seeded in Be shells, by density and composition non-uniformity from both oxygen and Ar, and in High Density Carbon shells by density nonuniformity. We present updated requirements for these nonuniformites, and compare to characterization of current shells. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  15. The Maximal Kinematical Invariance Group of Fluid Dynamics and Explosion-Implosion Duality

    CERN Document Server

    O'Raifeartaigh, Lochlainn

    2001-01-01

    It has recently been found that supernova explosions can be simulated in the laboratory by implosions induced in a plasma by intense lasers. A theoretical explanation is that the inversion transformation ($\\Sigma: t \\to -1/t, {\\bf x}\\to {\\bf x}/t$), leaves the Euler equations of fluid dynamics, with standard polytropic exponent, invariant. This implies that the kinematical invariance group of the Euler equations is larger than the Galilei group. In this paper we determine, in a systematic manner, the maximal invariance group ${\\cal G}$ of general fluid dynamics and show that it is a semi-direct product ${\\cal G} = SL(2,R) \\wedge G$, where the $SL(2,R)$ group contains the time-translations, dilations and the inversion $\\Sigma$, and $G$ is the static (nine-parameter) Galilei group. A subtle aspect of the inclusion of viscosity fields is discussed and it is shown that the Navier-Stokes assumption of constant viscosity breaks the $SL(2, R)$ group to a two-parameter group of time translations and dilations in a te...

  16. Hydrodynamic Instability Growth in Polar-Direct-Drive Implosions at the National Ignition Facility

    Science.gov (United States)

    Hohenberger, M.; Shvydky, A.; Radha, P. B.; Rosenberg, M. J.; Goncharov, V. N.; Marshall, F. J.; Knauer, J. P.; Regan, S. P.; Sangster, T. C.; Nikroo, A.; Wallace, R. J.

    2015-11-01

    Polar direct drive (PDD) is an alternative, direct-drive inertial confinement fusion platform being developed at the National Ignition Facility (NIF). Shell stability of the target is of key importance for an optimized performance. We have begun an experimental campaign to characterize Rayleigh-Taylor (RT) growth and laser imprint in spherical PDD implosions on the NIF. Plastic, cone-in-shell targets with an outer diameter of ~ 2 . 2 mm were imploded, and the RT-amplified shell mass modulations were tracked via measurements of the 2-D optical depth variations using soft x-ray radiography. The RT growth of discrete modes was investigated by machining single-mode, sinusoidal corrugations onto the target surface, which acted as well-characterized seeds. We will present platform characterization and backlighter optimization data as well as experimental results of instability growth in spherical PDD experiments on the NIF. The experimental data will be compared to 2-D DRACO simulations and strategies for measuring high l-mode perturbations > 300 and for mitigating imprint in future PDD experiments will be discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. Mitigation of Two-Plasmon Decay in Direct-Drive Implosions Using Multilayer Targets

    Science.gov (United States)

    Froula, D. H.; Goncharov, V. N.; Follett, R. K.; Henchen, R. J.; Yaakobi, B.; Edgell, D. H.; Solodov, A. A.; Myatt, J. F.; Shaw, J. G.; Stoeckl, C.; Bonino, M. J.; Sangster, T. C.

    2015-11-01

    Mitigation of cross-beam energy transfer in direct-drive implosions may increase the hot-electron preheat above acceptable levels for ignition. To study preheat mitigation concepts on OMEGA, a thin layer (0.6 μm) of Si in the target ablator is being considered to increase the electron temperature at the quarter-critical surface. A beryllium inner layer (6 μm thick) is used to increase the hydrodynamic efficiency and an outer layer of CH-doped Si (4 μm thick) reduces the laser imprint. Spatially resolved Thomson-scattering measurements show a 15% increase in the electron temperature at the quarter-critical surface and the time-resolved hot electrons are reduced by a factor of 8 compared with a standard CH target. The shell trajectory in the multilayer targets is significantly faster than the CH target, resulting in a factor-of-3 increase in the neutron yield. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  18. Inference of ICF implosion core mix using experimental data and theoretical mix modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sherrill, Leslie Welser [Los Alamos National Laboratory; Haynes, Donald A [Los Alamos National Laboratory; Cooley, James H [Los Alamos National Laboratory; Sherrill, Manolo E [Los Alamos National Laboratory; Mancini, Roberto C [UNR; Tommasini, Riccardo [LLNL; Golovkin, Igor E [PRISM COMP. SCIENCES; Haan, Steven W [LLNL

    2009-01-01

    The mixing between fuel and shell materials in Inertial Confinement Fusion (lCF) implosion cores is a current topic of interest. The goal of this work was to design direct-drive ICF experiments which have varying levels of mix, and subsequently to extract information on mixing directly from the experimental data using spectroscopic techniques. The experimental design was accomplished using hydrodynamic simulations in conjunction with Haan's saturation model, which was used to predict the mix levels of candidate experimental configurations. These theoretical predictions were then compared to the mixing information which was extracted from the experimental data, and it was found that Haan's mix model predicted trends in the width of the mix layer as a function of initial shell thickness. These results contribute to an assessment of the range of validity and predictive capability of the Haan saturation model, as well as increasing confidence in the methods used to extract mixing information from experimental data.

  19. Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers

    Directory of Open Access Journals (Sweden)

    Shiraga H.

    2013-11-01

    Full Text Available The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53- μm Gekko-XII, and the 1.053- μm beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (γ rays and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (γ,n reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 × 107 was observed. Heating efficiency was estimated to be 10–20% assuming a uniform temperature rise model.

  20. Time Domain Analysis of Transmit/Receive Dipole Pair Array

    Institute of Scientific and Technical Information of China (English)

    Zheng Li-zhi; Xiao Bo-xur; Zhu Guo-qiang; Yang Zi-jie

    2003-01-01

    We introduce a new transmit/receive dipole pair array to obtain a compact quasi-monostatic antenna structure for ground penetrating radar systems. And we analyze this transmit/receive dipole pair array in time domain. The numerical results show that if the distance between the transmit antenna and receive antenna is appropriate the array configuration is adoptable.

  1. Array antenna diagnostics with the 3D reconstruction algorithm

    DEFF Research Database (Denmark)

    Cappellin, Cecilia; Meincke, Peter; Pivnenko, Sergey;

    2012-01-01

    The 3D reconstruction algorithm is applied to a slotted waveguide array measured at the DTU-ESA Spherical Near-Field Antenna Test Facility. One slot of the array is covered by conductive tape and an error is present in the array excitation. Results show the accuracy obtainable by the 3D...

  2. Solitons in optomechanical arrays.

    Science.gov (United States)

    Gan, Jing-Hui; Xiong, Hao; Si, Liu-Gang; Lü, Xin-You; Wu, Ying

    2016-06-15

    We show that optical solitons can be obtained with a one-dimensional optomechanical array that consists of a chain of periodically spaced identical optomechanical systems. Unlike conventional optical solitons, which originate from nonlinear polarization, the optical soliton here stems from a new mechanism, namely, phonon-photon interaction. Under proper conditions, the phonon-photon induced nonlinearity that refers to the optomechanical nonlinearity will exactly compensate the dispersion caused by photon hopping of adjacent optomechanical systems. Moreover, the solitons are capable of exhibiting very low group velocity, depending on the photon hopping rate, which may lead to many important applications, including all-optical switches and on-chip optical architecture. This work may extend the range of optomechanics and nonlinear optics and provide a new field to study soliton theory and develop corresponding applications. PMID:27304261

  3. BOLOMETRIC ARRAYS FOR MILLIMETER WAVELENGTHS

    Directory of Open Access Journals (Sweden)

    E. Castillo

    2009-01-01

    Full Text Available During last years, semiconductor bolometers using thin lms have been developed at INAOE, speci cally boron-doped hydrogenated amorphous silicon lms. The characteristics shown by these devices made them attractive to be used in astronomical instrumentation, mainly in two-dimentional arrays. These detector arrays used at the Large Millimeter Telescope will make possible to obtain astronomical images in millimeter and submillimeter wavelengths. With this in mind, we are developing a method to produce, with enough reliability, bolometer arrays at INAOE. Until now, silicon nitride diaphragm arrays, useful as radiation absorbers, have succesfully been obtained. Sizes going from one to four millimeter by element in a consistent way; however we have not tested thermometers and metallic contact deposition yet. At the same time, we are working on two possible con gurations for the readout electronics; one of them using commercial components while the other will be an integrated circuit speci cally designed for this application. Both versions will work below 77K.

  4. Axiom turkey genotyping array

    Science.gov (United States)

    The Axiom®Turkey Genotyping Array interrogates 643,845 probesets on the array, covering 643,845 SNPs. The array development was led by Dr. Julie Long of the USDA-ARS Beltsville Agricultural Research Center under a public-private partnership with Hendrix Genetics, Aviagen, and Affymetrix. The Turk...

  5. Radiometric stability of Phase 3 WISP arrays

    Science.gov (United States)

    Flynn, David S.; Marlow, Steven A.; Bergin, Thomas P.; Murrer, Robert Lee

    2000-07-01

    Phase 3 WISP arrays and BRITE arrays are currently being used extensively in many projection systems in many different facilities. These arrays have not been annealed at the factory, and previous tests with the arrays have revealed instabilities in the radiometric output when the arrays are driven at higher voltages. In some applications, the instabilities can be avoided by operating the arrays at lower voltages. In many KHILS applications, it is desirable to drive the arrays with the highest possible voltages to simulate hot missile targets. In one KHILS application (the KHILS VAcuum Cold Chamber, KVACC), the arrays are cooled to near cryogenic temperatures and then driven to high voltages. At lower substrate temperatures, the characteristic responses of the emitters change. Thus, it is important that the response and the stability of the radiometric output of the arrays be well understood for various substrate temperatures, and that the arrays either be annealed or operated below the voltage where the emitters begin to anneal. KHILS has investigated annealing procedures in the past, but there was concern that the annealing procedures themselves -- driving the arrays at high voltages for long times -- would damage the arrays. In order to understand the performance of the arrays better, and to reduce risks associated with driving the arrays at high voltages and operating the arrays at low substrate temperatures, a systematic measurement program was initiated. The radiometric output of new Phase 3 WISP arrays was accurately measured as a function of voltage and time. Arrays designated for testing were driven to the higher voltages and the radiometric output was measured for as long as two hours. Curves indicative of the annealing were observed, and it was determined that the maximum stable output without annealing was about 500 K (MWIR apparent temperature). Blocks of emitters were annealed and tested again. It was determined that stable output of as much as 680 K

  6. Hohlraum-driven mid-Z (SiO2) double-shell implosions on the omega laser facility and their scaling to NIF.

    Science.gov (United States)

    Robey, H F; Amendt, P A; Milovich, J L; Park, H-S; Hamza, A V; Bono, M J

    2009-10-01

    High-convergence, hohlraum-driven implosions of double-shell capsules using mid-Z (SiO2) inner shells have been performed on the OMEGA laser facility [T. R. Boehly, Opt. Commun. 133, 495 (1997)]. These experiments provide an essential extension of the results of previous low-Z (CH) double-shell implosions [P. A. Amendt, Phys. Rev. Lett. 94, 065004 (2005)] to materials of higher density and atomic number. Analytic modeling, supported by highly resolved 2D numerical simulations, is used to account for the yield degradation due to interfacial atomic mixing. This extended experimental database from OMEGA enables a validation of the mix model, and provides a means for quantitatively assessing the prospects for high-Z double-shell implosions on the National Ignition Facility [Paisner, Laser Focus World 30, 75 (1994)].

  7. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF.

    Science.gov (United States)

    Rinderknecht, H G; Johnson, M Gatu; Zylstra, A B; Sinenian, N; Rosenberg, M J; Frenje, J A; Waugh, C J; Li, C K; Sèguin, F H; Petrasso, R D; Rygg, J R; Kimbrough, J R; MacPhee, A; Collins, G W; Hicks, D; Mackinnon, A; Bell, P; Bionta, R; Clancy, T; Zacharias, R; Döppner, T; Park, H S; LePape, S; Landen, O; Meezan, N; Moses, E I; Glebov, V U; Stoeckl, C; Sangster, T C; Olson, R; Kline, J; Kilkenny, J

    2012-10-01

    The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted ρR measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D(3)He implosions using DD or DT neutrons with an accuracy better than ±70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions using D(3)He protons and DD-neutrons, respectively.

  8. Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA

    Science.gov (United States)

    Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.

    2016-07-01

    A record fuel hot-spot pressure Phs=56 ±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ˜60 % of the value required for ignition [A. Bose et al., Phys. Rev. E 93, LM15119ER (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

  9. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF

    International Nuclear Information System (INIS)

    The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted ρR measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D3He implosions using DD or DT neutrons with an accuracy better than ±70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D3He-filled surrogate implosions using D3He protons and DD-neutrons, respectively.

  10. Radiative shocks produced from spherical cryogenic implosions at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Pak, A.; Divol, L.; Weber, S.; Atherton, J.; Bennedetti, R.; Bradley, D. K.; Callahan, D.; Casey, D. T.; Dewald, E.; Döppner, T.; Edwards, M. J.; Glenn, S.; Hicks, D.; Hsing, W. W.; Izumi, N.; Jones, O. S.; Khan, S. F.; Lindl, J.; Landen, O. L.; Le Pape, S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2013-05-15

    Spherically expanding radiative shock waves have been observed from inertially confined implosion experiments at the National Ignition Facility. In these experiments, a spherical fusion target, initially 2 mm in diameter, is compressed via the pressure induced from the ablation of the outer target surface. At the peak compression of the capsule, x-ray and nuclear diagnostics indicate the formation of a central core, with a radius and ion temperature of ∼20 μm and ∼ 2 keV, respectively. This central core is surrounded by a cooler compressed shell of deuterium-tritium fuel that has an outer radius of ∼40 μm and a density of >500 g/cm{sup 3}. Using inputs from multiple diagnostics, the peak pressure of the compressed core has been inferred to be of order 100 Gbar for the implosions discussed here. The shock front, initially located at the interface between the high pressure compressed fuel shell and surrounding in-falling low pressure ablator plasma, begins to propagate outwards after peak compression has been reached. Approximately 200 ps after peak compression, a ring of x-ray emission created by the limb-brightening of a spherical shell of shock-heated matter is observed to appear at a radius of ∼100 μm. Hydrodynamic simulations, which model the experiment and include radiation transport, indicate that the sudden appearance of this emission occurs as the post-shock material temperature increases and upstream density decreases, over a scale length of ∼10 μm, as the shock propagates into the lower density (∼1 g/cc), hot (∼250 eV) plasma that exists at the ablation front. The expansion of the shock-heated matter is temporally and spatially resolved and indicates a shock expansion velocity of ∼300 km/s in the laboratory frame. The magnitude and temporal evolution of the luminosity produced from the shock-heated matter was measured at photon energies between 5.9 and 12.4 keV. The observed radial shock expansion, as well as the magnitude and temporal

  11. Using HT and DT gamma rays to diagnose mix in Omega capsule implosions

    Science.gov (United States)

    Schmitt, M. J.; Herrmann, H. W.; Kim, Y. H.; McEvoy, A. M.; Zylstra, A.; Hammel, B. A.; Sepke, S. M.; Leatherland, A.; Gales, S.

    2016-05-01

    Experimental evidence [1] indicates that shell material can be driven into the core of Omega capsule implosions on the same time scale as the initial convergent shock. It has been hypothesized that shock-generated temperatures at the fuel/shell interface in thin exploding pusher capsules diffusively drives shell material into the gas core between the time of shock passage and bang time. We propose a method to temporally resolve and observe the evolution of shell material into the capsule core as a function of fuel/shell interface temperature (which can be varied by varying the capsule shell thickness). Our proposed method uses a CD plastic capsule filled with 50/50 HT gas and diagnosed using gas Cherenkov detection (GCD) to temporally resolve both the HT “clean” and DT “mix” gamma ray burn histories. Simulations using Hydra [2] for an Omega CD-lined capsule with a sub-micron layer of the inside surface of the shell pre-mixed into a fraction of the gas region produce gamma reaction history profiles that are sensitive to the depth to which this material is mixed. An experiment to observe these differences as a function of capsule shell thickness is proposed to determine if interface mixing is consistent with thermal diffusion λii∼T2/Z2ρ at the gas/shell interface. Since hydrodynamic mixing from shell perturbations, such as the mounting stalk and glue, could complicate these types of capsule-averaged temporal measurements, simulations including their effects also have been performed showing minimal perturbation of the hot spot geometry.

  12. High aspect ratio hard x-ray (> 100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Doppner, T; Dewald, E; Divol, L; Burns, S; Izumi, N; Kline, J; LaCaille, G; McNaney, J; Prasad, R; Thomas, C A; Glenzer, S H; Landen, O; Author, A; Author, S G; Author, T

    2012-05-01

    We have fielded a multi-pinhole, hard x-ray (> 100 keV) imager to measure the spatially-resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions, and are a source of preheat to the deuterium-tritium fuel that could limit the compressibility required for ignition and burn. Our hard x-ray imaging measurements allow to set an upper limit to the DT fuel preheat, which we find is acceptable in current capsule implosions on the NIF.

  13. A derivation of bulk-motion insensitive implosion metrics inferred from neutron and high-energy x-ray emission in a series of high yield implosions on the NIF

    Science.gov (United States)

    Springer, P. T.; Macphee, A. G.; Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Cerjan, C. J.; Dewald, E. L.; Dittrich, T. R.; Doeppner, T.; Edgell, D. H.; Edwards, M. J.; Gaffney, J.; Grim, G. P.; Haan, S.; Hammer, J. H.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Milovich, J.; Munro, D. H.; Pak, A.; Park, H. S.

    2015-11-01

    A suite of nuclear and x-ray data is used to deduce key implosion performance metrics at stagnation including the hotspot pressure, energy, and the role of alpha heating on producing the observed yield. Key to this analysis is a determination of the burn-averaged temperature of the hot plasma so that the nuclear reactivity and yield can then be used to deduce the plasma density and pressure. In this presentation we examine the systematics of both neutron and high-energy x-ray emission (22 keV x-ray monochromator) from a series of high yield implosions on the NIF. The advantage of incorporating high energy x-rays into the analysis is their insignificant attenuation and insensitivity to bulk flows, thus providing insight as to whether these effects complicate the interpretation of the nuclear data, and that a precipitous drop in their production is expected as the thermal temperature is reduced. A dynamic model for hotspot assembly is developed that incorporates thermal conduction, radiative losses, and alpha heating, which simultaneously matches both neutron and x-ray data with nearly identical nuclear and x-ray derived thermal temperatures. Work performed under the auspices of the USDoE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  14. The Square Kilometre Array

    CERN Document Server

    Lazio, Joseph

    2009-01-01

    The Square Kilometre Array (SKA) is intended as the next-generation radio telescope and will address fundamental questions in astrophysics, physics, and astrobiology. The international science community has developed a set of Key Science Programs: (1) Emerging from the Dark Ages and the Epoch of Reionization, (2) Galaxy Evolution, Cosmology, and Dark Energy, (3) The Origin and Evolution of Cosmic Magnetism, (4) Strong Field Tests of Gravity Using Pulsars and Black Holes, and (5) The Cradle of Life/Astrobiology. In addition, there is a design philosophy of "exploration of the unknown," in which the objective is to keep the design as flexible as possible to allow for future discoveries. Both a significant challenge and opportunity for the SKA is to obtain a significantly wider field of view than has been obtained with radio telescopes traditionally. Given the breadth of coverage of cosmic magnetism and galaxy evolution in this conference, I highlight some of the opportunities that an expanded field of view will...

  15. Power enhancement by increasing the initial array radius and wire number of tungsten Z pinches

    International Nuclear Information System (INIS)

    Tungsten wire array implosions on the 7- to 8-MA Saturn generator have been optimized using wire number and array diameter variations to produce 75±10TW of x rays with total energy outputs of 450±50kJ. By increasing the number of wires in a 12.5-mm-diam array from 24 to 70 and simultaneously decreasing the individual wire diameter from 13 to 7.5 μm, the total radiated power increased from 20±3 to 40±6TW and the x-ray pulse width decreased from 18 to 8.5 ns. In addition, a diameter scan at an implosion time of 50±5ns showed that the pulse width has a strong dependence on collapse velocity and wire thickness. For the largest diameter load of 17.5 mm with 120 5-μm-diam wires, a 4-ns pulse width with a peak power of 75±10TW was achieved: four times power gain over the 20-TW electrical power generated by the pulsed power system. Time-resolved pinhole photography confirms that the power enhancement with increased wire number is associated with the plasma achieving a tighter compression and better axial uniformity. For the higher-velocity implosions, we infer from two-dimensional radiation-magnetohydrodynamic calculations that the plasma becomes hotter and hence radiates at a higher brightness temperature. Zero- and two-dimensional load models coupled with a detailed circuit model have shown expected radial kinetic energies in the range of 100 endash 200 kJ. The total radiated energy of >400kJ in a 4 endash 20-ns FWHM pulse exceeds the total kinetic energy by more than a factor of 2. Two-dimensional, three-temperature simulations reproduce the observed trends in powers and pulse widths by using a variable initial random density perturbation. These calculations also indicate that the radiated energy is accounted for by the total work done on the plasma by the magnetic field. copyright 1997 The American Physical Society

  16. Kinetic simulation of direct-drive capsule implosions and its comparison with experiments and radiation hydrodynamic simulation

    Science.gov (United States)

    Kwan, Thomas; Le, Ari; Schmitt, Mark; Herrmann, Hans; Batha, Steve

    2015-11-01

    We have carried out simulations of direct-drive capsule implosion experiments conducted on Omega laser facility at the Laboratory of Laser energetics of the University of Rochester. The capsules had a glass shell (SiO2) with D, T, He-3 fills at various proportions. One-dimensional radiation hydrodynamic calculations and kinetic particle/hybrid simulations with LSP were carried out for the post-shot analysis to compare neutron yield, yield ratio, and shell convergence in assessing the effects of plasma kinetic effects. The LSP simulations were initiated with the output from the rad-hydro simulations at the end of the laser-drive. The electrons are treated as a fluid while all the ion species by the kinetic PIC technique. Our LSP simulations clearly showed species separation between the deuterons, tritons and He-3 during the implosion but significantly less after the compression. The neutron yield, gamma bang-time and -width from the LSP simulations compared favorably with experiments. Detail comparison among the kinetic simulations, rad-hydro simulations, and experimental results will be presented. Work performed under the auspices of the US Department of Energy by Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

  17. Numerical Modeling of the Sensitivity of X-Ray Driven Implosions to Low-Mode Flux Asymmetries

    CERN Document Server

    Scott, R H H; Bradley, D K; Callahan, D A; Edwards, M J; Haan, S W; Jones, O S; Spears, B K; Marinak, M M; Town, R P J; Norreys, P A; Suter, L J

    2012-01-01

    The sensitivity of inertial confinement fusion implosions of the type performed on the National Ignition Facility (NIF) to low-mode flux asymmetries has been investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P4), resulting from associated low order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the DT ice layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of kinetic to internal energy of the central hot spot, thus reducing neutron yield. Furthermore, synthetic gated x-ray images of the hot spot self-emission indicate that P4 shapes may be unquantifiable for DT layered capsules. Instead the positive P4 asymmetry aliases itself as an oblate P4 in the x-ray self emission images. Correction of this apparent P2 distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of...

  18. Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare

    CERN Document Server

    Dudik, Jaroslav; Janvier, Miho; Mulay, Sargam M; Karlicky, Marian; Aulanier, Guillaume; Del Zanna, Giulio; Dzifcakova, Elena; Mason, Helen E; Schmieder, Brigitte

    2016-01-01

    We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. The slipping reconnection is found to be present throughout the flare from its early phase. Flare loops are seen to slip in opposite directions towards both ends of the ribbons. Velocities of 20--40 km\\,s$^{-1}$ are found within time windows where the slipping is well resolved. The warm coronal loops exhibit expanding and contracting motions that are interpreted as displacements due to the growing flux rope that subsequently erupts. This flux rope existed and erupted before the onset of apparent coronal implosion. This indicates that the energy release proceeds by slipping reconnection and not via coronal implosion. The slipping reconnection leads to changes in the geometry of the observed structures at the \\textit{IRIS} slit position, from flare loop top to the footpoints in the ribbons. This results in variations of the observed velocities of chromosph...

  19. Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare

    Science.gov (United States)

    Dudík, Jaroslav; Polito, Vanessa; Janvier, Miho; Mulay, Sargam M.; Karlický, Marian; Aulanier, Guillaume; Del Zanna, Giulio; Dzifčáková, Elena; Mason, Helen E.; Schmieder, Brigitte

    2016-05-01

    We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. Slipping reconnection is found to be present throughout the flare from its early phase. Flare loops are seen to slip in opposite directions toward both ends of the ribbons. Velocities of 20–40 km s‑1 are found within time windows where the slipping is well resolved. The warm coronal loops exhibit expanding and contracting motions that are interpreted as displacements due to the growing flux rope that subsequently erupts. This flux rope existed and erupted before the onset of apparent coronal implosion. This indicates that the energy release proceeds by slipping reconnection and not via coronal implosion. The slipping reconnection leads to changes in the geometry of the observed structures at the Interface Region Imaging Spectrograph slit position, from flare loop top to the footpoints in the ribbons. This results in variations of the observed velocities of chromospheric evaporation in the early flare phase. Finally, it is found that the precursor signatures, including localized EUV brightenings as well as nonthermal X-ray emission, are signatures of the flare itself, progressing from the early phase toward the impulsive phase, with the tether-cutting being provided by the slipping reconnection. The dynamics of both the flare and outlying coronal loops is found to be consistent with the predictions of the standard solar flare model in three dimensions.

  20. Studies of implosion dynamics of D3He gas-filled plastic targets using nuclear diagnostics at OMEGA

    International Nuclear Information System (INIS)

    Information about target-implosion dynamics is essential for understanding how assembly occurs. Without carefully tailored assembly of the fuel, hot-spot ignition on National Ignition Facility (NIF) will fail. Hot spot ignition relies on shock convergence to 'ignite' the hot spot (shock burn), followed by propagation of the burn into the compressed shell material (compressive burn). The relationship between these events must be understood to ensure the success of Inertial Confinement Fusion (ICF) ignition. To further improve our knowledge about the timing of these events, temporal evolution of areal density (density times radius, normally referred to as ρR) and burn of direct-drive, D3He gas-filled plastic target implosions have been studied using dd neutrons and d3He protons. The proton temporal diagnostic (PTD) code was developed for this purpose. ρR asymmetries were observed at shock-bang time (time of peak burn during shock phase) and grew approximately twice as fast as the average ρR, without any phase changes. Furthermore, it was observed that the shock-bang and compression-bang time occur earlier, and that the time difference between these events decreases for higher laser energy on target, which indicates that the compression-bang time is more sensitive to the variation of laser energy on target. It was also observed that the duration of shock and compression phase might decrease for higher laser energy on target

  1. Preparation and characterization of haematite nanowire arrays

    CERN Document Server

    Xue, D S; Liu, Q F; Zhang, L Y

    2003-01-01

    Arrays of alpha-Fe sub 2 O sub 3 nanowires embedded in anodic alumina membranes were obtained after heat-treating beta-FeOOH nanowire arrays fabricated by electrochemical deposition. Haematite polycrystalline nanowires with maximum length of about 7 mu m and average diameter of about 120 nm were characterized by means of x-ray diffraction and transmission electron microscopy. The Morin temperature below 80 K and Neel temperature of about 350 K for the alpha-Fe sub 2 O sub 3 nanowire arrays, far lower than those of bulk material, were measured by Moessbauer spectroscopy and using a Magnetic Property Measurement System.

  2. Application of Array Measurement in Blind Identification

    Institute of Scientific and Technical Information of China (English)

    王勇; 孙连明; 刘文江

    2003-01-01

    This paper deals with blind identification and deconvolution algorithm for an arbitrary, possibly white or colored, stationary or nonstationary signal, which is observed through array sensors. By using multiple sensors with their individual outputs sampled at a rate 1/T, one can obtain cyclostationary signals. They can be considered as a single-input multiple-output model with an identical but unknown input signal. With the array measurement, an algorithm for estimating the system transfer function model and its parameters is presented.

  3. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  4. Pacific Array (Transportable Broadband Ocean Floor Array)

    Science.gov (United States)

    Kawakatsu, Hitoshi; Ekstrom, Goran; Evans, Rob; Forsyth, Don; Gaherty, Jim; Kennett, Brian; Montagner, Jean-Paul; Utada, Hisashi

    2016-04-01

    Based on recent developments on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry1, together with advances in the seismic analysis methodology, have enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (azimuthal, and hopefully radial), with deployments of ~15 broadband ocean bottom seismometers (BBOBSs). Having ~15 BBOBSs as an array unit for a 2-year deployment, and repeating such deployments in a leap-frog way or concurrently (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure beneath Pacific ocean, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations is essential: if three countries/institutions participate this endeavor together, Pacific Array may be accomplished within five-or-so years.

  5. Transient phenomena in the final implosion stage at the PF-1000 facility

    International Nuclear Information System (INIS)

    is equal to 1 MJ so it makes this device one of the few where one can investigate an effect of the 'neutron saturation' phenomenon. It was found about 20 years ago and is still under discussion up to now. During these experiments we concentrated our efforts in an investigation of very fast non-equilibrium phenomena taking place in the final stage of plasma implosion, i.e. namely in the period of time, when neutron pulse is generated

  6. Telescope Array Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, H.; Yoshida, S. [Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522 (Japan); Yoshii, H. [Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577 (Japan); Tanaka, K. [Hiroshinma City University, 3-4-1 Ozuka-Higashi, Asa-Minami-ku, Hiroshima, 731-3194 (Japan); Cohen, F.; Fukushima, M.; Hayashida, N.; Hiyama, K.; Ikeda, D.; Kido, E.; Kondo, Y.; Nonaka, T.; Ohnishi, M.; Ohoka, H.; Ozawa, S.; Sagawa, H.; Sakurai, N.; Shibata, T.; Shimodaira, H.; Takeda, M. [ICRR, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan)] (and others)

    2008-01-15

    The TA observatory is a hybrid detector system consisting of both a surface detector array as well as a set of fluorescence detectors. The observatory will measure the energy spectrum, anisotropy and composition of ultra-high energy cosmic rays. The surface detectors are being deployed and the array should be complete by the end of February, 2007. We will soon be collecting hybrid data at the Telecope Array.

  7. Array of planar waveguide lasers with 50 GHz frequency spacing

    DEFF Research Database (Denmark)

    Guldberg-Kjær, Søren Andreas; Laurent-Lund, Christian; Sckerl, Mads W.

    1999-01-01

    Waveguide laser arrays are demonstrated using planar silica-on-silicon technology. Excellent control over frequency separation is obtained with a single phase mask.......Waveguide laser arrays are demonstrated using planar silica-on-silicon technology. Excellent control over frequency separation is obtained with a single phase mask....

  8. Integrated avalanche photodiode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Eric S.

    2015-07-07

    The present disclosure includes devices for detecting photons, including avalanche photon detectors, arrays of such detectors, and circuits including such arrays. In some aspects, the detectors and arrays include a virtual beveled edge mesa structure surrounded by resistive material damaged by ion implantation and having side wall profiles that taper inwardly towards the top of the mesa structures, or towards the direction from which the ion implantation occurred. Other aspects are directed to masking and multiple implantation and/or annealing steps. Furthermore, methods for fabricating and using such devices, circuits and arrays are disclosed.

  9. Experimental results of radiation-driven, layered deuterium-tritium implosions with adiabat-shaped drives at the National Ignition Facility

    Science.gov (United States)

    Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Casey, D. T.; Clark, D. S.; Jones, O. S.; Milovich, J. L.; Peterson, J. L.; Bachmann, B.; Baker, K. L.; Benedetti, L. R.; Berzak Hopkins, L. F.; Bionta, R.; Bond, E.; Bradley, D. K.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Chen, K.-C.; Goyon, C.; Grim, G.; Dixit, S. N.; Eckart, M. J.; Edwards, M. J.; Farrell, M.; Fittinghoff, D. N.; Frenje, J. A.; Gatu-Johnson, M.; Gharibyan, N.; Haan, S. W.; Hamza, A. V.; Hartouni, E.; Hatarik, R.; Havre, M.; Hohenberger, M.; Hoover, D.; Hurricane, O. A.; Izumi, N.; Jancaitis, K. S.; Khan, S. F.; Knauer, J. P.; Kroll, J. J.; Kyrala, G.; Lafortune, K. N.; Landen, O. L.; Ma, T.; MacGowan, B. J.; MacPhee, A. G.; Mauldin, M.; Merrill, F. E.; Moore, A. S.; Nagel, S.; Nikroo, A.; Pak, A.; Patel, P. K.; Ralph, J. E.; Sayre, D. B.; Shaughnessy, D.; Spears, B. K.; Tommasini, R.; Turnbull, D. P.; Velikovich, A. L.; Volegov, P. L.; Weber, C. R.; Widmayer, C. C.; Yeamans, C.

    2016-10-01

    Radiation-driven, layered deuterium-tritium (DT) implosions were carried out using 3-shock and 4-shock "adiabat-shaped" drives and plastic ablators on the National Ignition Facility (NIF) [E. M. Campbell et al., AIP Conf. Proc. 429, 3 (1998)]. The purpose of these shots was to gain further understanding on the relative performance of the low-foot implosions of the National Ignition Campaign [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] versus the subsequent high-foot implosions [T. Döppner et al., Phys. Rev. Lett. 115, 055001 (2015)]. The neutron yield performance in the experiment with the 4-shock adiabat-shaped drive was improved by factors ˜3 to ˜10, compared to five companion low-foot shots despite large low-mode asymmetries of DT fuel, while measured compression was similar to its low-foot companions. This indicated that the dominant degradation source for low-foot implosions was ablation-front instability growth, since adiabat shaping significantly stabilized this growth. For the experiment with the low-power 3-shock adiabat-shaped drive, the DT fuel compression was significantly increased, by ˜25% to ˜36%, compared to its companion high-foot implosions. The neutron yield increased by ˜20%, lower than the increase of ˜50% estimated from one-dimensional scaling, suggesting the importance of residual instabilities and asymmetries. For the experiment with the high-power, 3-shock adiabat-shaped drive, the DT fuel compression was slightly increased by ˜14% compared to its companion high-foot experiments. However, the compression was reduced compared to the lower-power 3-shock adiabat-shaped drive, correlated with the increase of hot electrons that hypothetically can be responsible for reduced compression in high-power adiabat-shaped experiments as well as in high-foot experiments. The total neutron yield in the high-power 3-shock adiabat-shaped shot N150416 was 8.5 × 1015 ± 0.2 × 1015, with the fuel areal density of 0.90 ± 0.07 g/cm2

  10. Recent Results from Telescope Array

    CERN Document Server

    Fukushima, M

    2015-01-01

    The Telescope Array (TA) is an experiment to observe Ultra-High Energy Cosmic Rays (UHECRs). TA's recent results, the energy spectrum and anisotropy based on the 6-year surface array data, and the primary composition obtained from the shower maximum Xmax are reported. The spectrum demonstrates a clear dip and cutoff. The shape of the spectrum is well described by the energy loss of extra-galactic protons interacting with the cosmic microwave background (CMB). Above the cutoff, a medium-scale (20 degrees radius) flux enhancement was observed near the Ursa-Major. A chance probability of creating this hotspot from the isotropic flux is 4.0 sigma. The measured Xmax is consistent with the primary being proton or light nuclei for energies 10^18.2 eV - 10^19.2 eV.

  11. The Largest Multi-Planar Wire Arrays on Zebra with LCM and their Applications

    Science.gov (United States)

    Safronova, A. S.; Kantsyrev, V. L.; Weller, M. E.; Shlyaptseva, V. V.; Shrestha, I. K.; Lorance, M. Y.; Stafford, A.; Schultz, K. A.; Coverdale, C. A.; Chuvatin, A. S.

    2015-11-01

    Two new approaches of i) simultaneous study of implosion and radiative characteristics of different materials in wire array Z-pinch plasma in one shot [Safronova et al, PoP 21, 031205 (2014)] and ii) investigation of larger sized wire arrays (to enhance energy coupling to plasmas and provide better diagnostic access) were further developed in experiments with 1.7 MA Zebra with a Load Current Multiplier. In particular, the largest multi-Planar Wire Arrays with two outer planes from alloyed Al wires placed as far from each other as at 19 mm (compare with 6 and 9 mm studied before) and with a modified central plane from Ni-60 (mostly Cu), were investigated. Though K-shell Al and L-shell Cu plasmas have similar temperatures and densities, the ablation dynamics and radiation of Al and Cu planes is somewhat different, which was investigated in detail using the full set of diagnostics and modeling. Advantages of using such wire arrays at higher currents to study plasma flow and radiation from different materials and jets are highlighted. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-NA0002075. SNL is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE under Contract DE-AC04-94AL85000.

  12. Shear-tensile/implosion (STI) source model: a good substitute to moment tensor in single-well monitoring of hydrofrac-induced seismicity

    Science.gov (United States)

    Sileny, J.

    2011-12-01

    Moment tensor (MT) is a general dipole source, but for practice it may be too general, its generality causing troubles during its reconstruction from noisy data in the inverse process, which may be additionally ill-conditioned due to inexact hypocenter location and/or availability of a rough velocity/attenuation model only. Then, the retrieved source may be biased, containing artifacts of a low-quality data or the inconsistent inverse problem. The crucial point for success in the retrieval of the mechanism is the station configuration. The extreme case of depleted configuration is a one well monitoring providing a single-azimuth observation only, which is a frequent case during hydrofracturing treatment of oil and gas wells. Then, the complete moment tensor cannot be retrieved from far-field data and additional constraints are necessary. To avoid the trouble, it seems reasonable to assume a simpler source model directly describing the physical phenomena anticipated in the foci of the induced events. A simple combination of a shear slip with a tensile crack or 1D implosion - the STI model - is a good alternative to the moment tensor. Its advantage is twofold: (1) being described by smaller number of parameters, it removes the under-determination of the MT from single-azimuth observation, and (2) containing simple physical mechanisms only, namely a shear slip and tensile crack (or open crack implosion), it avoids unphysical sources like the compensated linear-vector dipole (CLVD) a priori. This feature helps a lot just in cases of a poor location or velocity modeling. We have tested the STI model in a series of synthetic experiments simulating a single well and two-well monitoring, the Cotton Valley (E Texas) hydrofracture treatment being the pattern of the observation. As theoretical mechanisms, a strike-slip and dip-slip with variable off-plane slip component were considered. The synthetic data were inverted by using Green's function simulating a mislocation of the

  13. Dynamics of cylindrical converging shock waves interacting with aerodynamic obstacle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Vignati, F.; Guardone, A., E-mail: alberto.guardone@polimi.it [Department of Aerospace Science and Technology, Politecnico di Milano, via La Masa 34, 20156 Milano (Italy)

    2015-06-15

    Cylindrical converging shock waves interacting with an array of aerodynamic obstacles are investigated numerically for diverse shock strengths and for different obstacle configurations in air in standard conditions. The considered number of obstacles N is 4, 6, 8, 16, and 24. Obstacles are lenticular airfoils with thickness-to-chord ratios t/c of 0.07, 0.14, and 0.21. The distances of the airfoil leading edge from the shock focus point (r{sub LE})/(r{sub LE}{sup ref}) are 1, 2, and 2.5, where r{sub LE}{sup ref}=7 is the dimensionless reference distance from the origin. Considered impinging shock Mach numbers M{sub s} are 2.2, 2.7, and 3.2 at the reference distance from the origin. The reference experimental configuration (N=8,t/c =0.14,r{sub LE}=7,M{sub s}=2.7) was proposed by Kjellander et al. [“Thermal radiation from a converging shock implosion,” Phys. Fluids 22, 046102 (2010)]. Numerical results compare fairly well to available one-dimensional models for shock propagation and to available experimental results in the reference configuration. Local reflection types are in good agreement with the classical criteria for planar shock waves. The main shock reshaping patterns are identified and their dependence on the shock strength and obstacle configuration is exposed. In particular, different shock patterns are observed after the leading edge reflection, which results in polygonal shock wave with N, 2N, 3N, and 4N sides. The largest temperature peak at the origin is obtained for the 8- and the 16-obstacle configurations and for the smallest thickness to length ratio, 0.07, located at distance from the origin of 2r{sub LE}{sup ref}. In terms of compression efficiency at the origin, the 16-obstacle configuration is found to perform slightly better than the reference 8-obstacle configuration—with an efficiency increase of about 2%-3%, which is well within the model accuracy—thus confirming the goodness of the obstacle arrangement proposed by Kjellander and

  14. Solar array deployment mechanism

    Science.gov (United States)

    Calassa, Mark C.; Kackley, Russell

    1995-05-01

    This paper describes a Solar Array Deployment Mechanism (SADM) used to deploy a rigid solar array panel on a commercial spacecraft. The application required a deployment mechanism design that was not only lightweight, but also could be produced and installed at the lowest possible cost. This paper covers design, test, and analysis of a mechanism that meets these requirements.

  15. Micromachined electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Edgewood, NM); Wessendorf, Kurt O. (Albuquerque, NM)

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  16. Microfabricated ion trap array

    Science.gov (United States)

    Blain, Matthew G.; Fleming, James G.

    2006-12-26

    A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

  17. Density controlled carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng F.; Tu, Yi

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  18. Analysis of the symmetry of the direct-drive target implosion under laser pulse of a megajoule scale

    Science.gov (United States)

    Demchenko, N. N.; Gus'kov, S. Yu; Kuchugov, P. A.; Rozanov, V. B.; Stepanov, R. V.; Vergunova, G. A.; Yakhin, R. A.; Zmitrenko, N. V.

    2016-05-01

    The class of direct-drive targets for the laser pulse of a megajoule scale is considered in the work. A distinctive feature of the design of these targets is a relatively low aspect ratio (outer DT-shell radius/shell thickness, A ∼ 10) to provide greater compression stability. The irradiation of the target surface is carried out by the shaped laser pulse on 2ω of Nd-laser. The influence of laser energy absorption inhomogeneity on the parameters of compression and burning of thermonuclear fuel on the final stage of implosion is studied in the work based on 1D and 2D numerical calculations. The results of 2D modeling show that in the case of target's offset from the point of beams crossing significantly greater reduction in the neutron yield is observed than in the case when only irregularities caused by the geometry of irradiation by the finite number of beams are taken into account.

  19. On the change in Inertial Confinement Fusion Implosions upon using an ab initio multiphase DT equation of state

    CERN Document Server

    Caillabet, Laurent; Salin, Gwenaël; Mazevet, Stéphane; Loubeyre, Paul

    2011-01-01

    Improving the description of the equation of state (EoS) of deuterium-tritium (DT) has recently been shown to change significantly the gain of an Inertial Confinement Fusion (ICF) target (Hu et al., PRL 104, 235003 (2010)). We use here an advanced multi-phase equation of state (EoS), based on ab initio calculations, to perform a full optimization of the laser pulse shape with hydrodynamic simulations starting from 19 K in DT ice. The thermonuclear gain is shown to be a robust estimate over possible uncertainties of the EoS. Two different target designs are discussed, for shock ignition and self-ignition. In the first case, the areal density and thermonuclear energy can be recovered by slightly increasing the laser energy. In the second case, a lower in-flight adiabat is needed, leading to a significant delay (3ns) in the shock timing of the implosion.

  20. Uniformity of spherical shock wave dynamically stabilized by two successive laser profiles in direct-drive inertial confinement fusion implosions

    Energy Technology Data Exchange (ETDEWEB)

    Temporal, M., E-mail: mauro.temporal@hotmail.com [Centre de Mathématiques et de Leurs Applications, ENS Cachan and CNRS, 61 Av. du President Wilson, F-94235 Cachan Cedex (France); Canaud, B. [CEA, DIF, F-91297 Arpajon Cedex (France); Garbett, W. J. [AWE plc, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Ramis, R. [ETSI Aeronáutica y del Espacio, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2015-10-15

    The implosion uniformity of a directly driven spherical inertial confinement fusion capsule is considered within the context of the Laser Mégajoule configuration. Two-dimensional (2D) hydrodynamic simulations have been performed assuming irradiation with two laser beam cones located at 49° and 131° with respect to the axis of symmetry. The laser energy deposition causes an inward shock wave whose surface is tracked in time, providing the time evolution of its non-uniformity. The illumination model has been used to optimize the laser intensity profiles used as input in the 2D hydro-calculations. It is found that a single stationary laser profile does not maintain a uniform shock front over time. To overcome this drawback, it is proposed to use two laser profiles acting successively in time, in order to dynamically stabilize the non-uniformity of the shock front.

  1. Design of an electronic charged particle spectrometer to measure (ρR), yield, and implosion symmetry on the OMEGA Upgrade

    International Nuclear Information System (INIS)

    The preliminary design for a state-of-the-art diagnostic that will measure a broad energy spectrum of charged particles generated in the OMEGA Upgrade facility is investigated. Using a set of photodiodes (∼10) and a 0.8 Tesla permanent magnet, the diagnostic will uniquely determine particle energies and identities from 0.2 MeV up to the maximum charged particle energies (10.6 MeV tritons, 12.5 MeV deuterons and 17.4 MeV protons). With its high density picture elements, each photodiode has 106 single-hit detectors, giving the spectrometer a dynamic range of 1 - 105 particles/shot. For example, in the case of a DT yield of 109 neutrons, about 100 knock-on charged particles will be detected when the spectrometer aperture is 60 cm from the implosion. Furthermore, the measurement of knock-on D and T spectra will allow ρR's up to 0.15 g/cm2 to be measured (for a 1 keV plasma), or 0.3 g/cm22 if hydrogen doping is used. In addition, the yield and slowing down of secondary protons may be used to determine ρR up to 0.3 g/cm2. Significantly, this diagnostic will also directly measure the DD fusion yield and energy degradation of nascent 3 MeV protons. By using two such compact spectrometers to measure the yield and spectra on widely separated ports around the OMEGA Upgrade target chamber, the implosion and bum symmetry can be determined. Furthermore, the ion temperature, and, in principle, even the electron temperature can be measured. The diagnostic and its development will be fully tested at several critical steps, utilizing 0.2-16 MeV protons (and several other charged particles and neutrons) from our absolutely calibrated Cockcroft-Walton facility

  2. Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, M. J., E-mail: mros@lle.rochester.edu; Séguin, F. H.; Rinderknecht, H. G.; Zylstra, A. B.; Li, C. K.; Sio, H.; Johnson, M. Gatu; Frenje, J. A.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Amendt, P. A.; Wilks, S. C.; Pino, J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Atzeni, S. [Dipartimento SBAI, Università di Roma “La Sapienza” and CNISM, Via A. Scarpa 14-16, I-00161 Roma (Italy); Hoffman, N. M.; Kagan, G.; Molvig, K. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Glebov, V. Yu.; Stoeckl, C.; Seka, W.; Marshall, F. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others

    2015-06-15

    The significance and nature of ion kinetic effects in D{sup 3}He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, N{sub K}) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolved measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (N{sub K} ∼ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects.

  3. Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging

    International Nuclear Information System (INIS)

    The significance and nature of ion kinetic effects in D3He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, NK) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolved measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (NK ∼ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects

  4. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  5. Introduction to adaptive arrays

    CERN Document Server

    Monzingo, Bob; Haupt, Randy

    2011-01-01

    This second edition is an extensive modernization of the bestselling introduction to the subject of adaptive array sensor systems. With the number of applications of adaptive array sensor systems growing each year, this look at the principles and fundamental techniques that are critical to these systems is more important than ever before. Introduction to Adaptive Arrays, 2nd Edition is organized as a tutorial, taking the reader by the hand and leading them through the maze of jargon that often surrounds this highly technical subject. It is easy to read and easy to follow as fundamental concept

  6. P systems with array objects and array rewriting rules

    Institute of Scientific and Technical Information of China (English)

    K.G. Subramanian; R. Saravanan; M. Geethalakshmi; P. Helen Chandra; M. Margenstern

    2007-01-01

    Array P systems were introduced by Pǎun Gh. which is linking the two areas of membrane computing and picture grammars. Puzzle grammars were introduced by us for generating connected picture arrays in the two-dimensional plane, motivated by the problem of tiling the plane. On the other hand, incorporating into arrays the developmental type of generation used in the well-known biologically motivated L systems, Siromoney and Siromoney proposed a very general rectangular array generating model, called extended controlled tabled L array system (ECTLAS). In this paper we introduce two variations of the array P system, called BPG array P system and parallel array P system. The former has in the regions array objects and basic puzzle grammar rules (BPG), which are a specific kind of puzzle grammar rules. In the latter, the regions have rectangular array objects and tables of context-free rules. We examine these two types of P systems for their array generative power.

  7. Flexible retinal electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Albuquerque, NM); Wessendorf, Kurt O. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  8. Expandable LED array interconnect

    Science.gov (United States)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  9. Protein Functionalized Nanodiamond Arrays

    Directory of Open Access Journals (Sweden)

    Liu YL

    2010-01-01

    Full Text Available Abstract Various nanoscale elements are currently being explored for bio-applications, such as in bio-images, bio-detection, and bio-sensors. Among them, nanodiamonds possess remarkable features such as low bio-cytotoxicity, good optical property in fluorescent and Raman spectra, and good photostability for bio-applications. In this work, we devise techniques to position functionalized nanodiamonds on self-assembled monolayer (SAMs arrays adsorbed on silicon and ITO substrates surface using electron beam lithography techniques. The nanodiamond arrays were functionalized with lysozyme to target a certain biomolecule or protein specifically. The optical properties of the nanodiamond-protein complex arrays were characterized by a high throughput confocal microscope. The synthesized nanodiamond-lysozyme complex arrays were found to still retain their functionality in interacting with E. coli.

  10. Design and Experiment of Multi-resolution Composite Digital Array Antenna

    Directory of Open Access Journals (Sweden)

    Tang Yue

    2016-06-01

    Full Text Available Because a sparse array has the advantages of a simplified structure and reduced cost in a radar system, radar technology based on the sparse array has gained widespread attention. To take advantage of the sparse array, in this paper, we designed a Multi-Resolution Composite digital Array antenna (MRCA, and then used it in single-target and multi-target detection experiments. Using the same number of array elements, our experimental results demonstrate that the MRCA can obtain a narrower main lobe and a lower side lobe, enhances the direction of the array antenna, and improves the angular resolution compared with the uniform linear array.

  11. Multi-Channel Detector Arrays for Heavy Ion Beam Probes

    Science.gov (United States)

    Aceto, Steven; Beckstead, Jeffrey; Castracane, James; Iguchi, H.; Fujisawa, A.; Demers, Diane; Schatz, John

    1997-11-01

    InterScience, Inc. has developed a multiple slit detector array for use with heavy ion beam probes. The first array was a twenty element array installed on the TEXT tokamak. An initial set of data was obtained with this array prior to the shutdown on the TEXT tokamak in December of 1995. More recently, a smaller detector array has been developed for use in the CHS torsatron in Nagoya. This array is smaller than the TEXT array, with ten elements, but contains two prototype sets of detector plates to determine the beam position. The operating conditions in CHS are expected to be much harsher than in TEXT, with ECH and NBI plasmas. Trajectory simulations allowed for the design of a tilted detector array in the CHS vacuum vessel. First tests of the CHS array will begin in the late summer of 1997. Other candidate machines for detector arrays are the MST reversed field pinch, in which a beam probe is expected to be installed in late 1997 or early 1998 and the Large Helical Device (LHD) which is expected to be operational in 1998. Design issues, trajectory simulations and array test results will be presented. Supported in part by the U.S. Department of Energy under Grant #DE-FG02-94ER81788

  12. Laser Dazzling of Focal Plane Array Cameras

    NARCIS (Netherlands)

    Schleijpen, H.M.A.; Heuvel, J.C. van den; Mieremet, A.J.; Mellier, B.; Putten, F.J.M. van

    2007-01-01

    Laser countermeasures against infrared focal plane array cameras aim to saturate the full camera image. In this paper we will discuss the results of three different dazzling experiments performed with MWIR lasers and show that the obtained results are independent of the read-out mechanism of the cam

  13. Methods of obtaining thermodynamic data

    International Nuclear Information System (INIS)

    The types of thermodynamic data needed to predict behavior of high temperature systems such as an overheated nuclear reactor in which the fuel has been exposed to water and oxygen are discussed. Procedures for obtaining the needed data are reviewed. 14 refs

  14. CNPC makes major breakthrough in array lateral logging technology

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    On October 12, 2011, the array lateral logging tool independently developed by CNPC Well Logging Company was successfully put to use at two production wells at Changqing Oilfield, obtaining high quality logging information. CNPC becomes the second company after Schlumberger in the world to master the array lateral logging technology, which can effectively identify layers as thin as 0.3 meter.

  15. Arrays of magnetic nanoparticles capped with alkylamines

    Indian Academy of Sciences (India)

    P John Thomas; P Saravanan; G U Kulkarni; C N R Rao

    2002-02-01

    Magnetic metal and metal oxide nanoparticles capped with alkylamines have been synthesized and characterized by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray analysis and magnetization measurements. Core-shell Pd–Ni particles with composition, Pd561Ni3000, (diameter ∼ 3.3 nm) are superparamagnetic at 5 K and organize themselves into two-dimensional crystalline arrays. Similar arrays are obtained with Pd561Ni3000Pd1500 nanoparticles containing an additional Pd shell. Magnetic spinel particles of -Fe2O3, Fe3O4 and CoFe2O4 of average diameters in the 4–6 nm range coated with octylamine are all supermagnetic at room temperature and yield close-packed disordered arrays. Relatively regular arrays are formed by dodecylamine-capped Fe3O4 nanoparticles (∼ 8.6 nm diameter) while well-ordered hexagonal arrays were obtained with octylamine-covered Co3O4 nanoparticles (∼ 4.2 nm diameter).

  16. Optimizing Chemical Sensor Array Sizes

    International Nuclear Information System (INIS)

    Optimal selection of array sensors for a chemical sensing application is a nontrivial task. It is commonly believed that ''more is better'' when choosing the number of sensors required to achieve good chemical selectivity. However, cost and system complexity issues point towards the choice of small arrays. A quantitative array optimization is carried out to explore the selectivity of arrays of partially-selective chemical sensors as a function of array size. It is shown that modest numbers (dozens) of target analytes are completely distinguished with a range of arrays sizes. However, the array selectivity and the robustness against sensor sensitivity variability are significantly degraded if the array size is increased above a certain number of sensors, so that relatively small arrays provide the best performance. The results also suggest that data analyses for very large arrays of partially-selective sensors will be optimized by separately anal yzing small sensor subsets

  17. Imaging antenna arrays

    Science.gov (United States)

    Rutledge, D. B.; Muha, M. S.

    1982-01-01

    Many millimeter and far-infrared imaging systems are limited in sensitivity and speed because they depend on a single scanned element. Because of recent advances in planar detectors such as Schottky diodes, superconducting tunnel junctions, and microbolometers, an attractive approach to this problem is a planar antenna array with integrated detectors. A planar line antenna array and optical system for imaging has been developed. The significant advances are a 'reverse-microscope' optical configuration and a modified bow-tie antenna design. In the 'reverse-microscope' configuration, a lens is attached to the bottom of the substrate containing the antennas. Imaging is done through the substrate. This configuration eliminates the troublesome effects of substrate surface waves. The substrate lens has only a single refracting surface, making possible a virtually aplanatic system, with little spherical aberration or coma. The array is characterized by an optical transfer function that is easily measured. An array with 19 dB crosstalk levels between adjacent antennas has been tested and it was found that the array captured 50 percent of the available power. This imaging system was diffraction limited.

  18. A passive synthetic aperture phase correction algorithm for the asymmetric twin-line array sonar

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A passive synthetic aperture based on phase correction algorithm for solving the port-starboard discrimination problem in the non-aligned towed twin-line array sonar, is described. This method creates a virtual array through applying the estimated phase correction into one array of twin-line arrays. Because the synthetic virtual array is aligned with the other array in twin-line arrays, the right port-starboard discriminated results can be obtained by array processing based on the new synthetic twin-line array. The effect of proposed method has been shown by simulated and sea-trials results in towed twin-line array sonar. With low extra computational loads, the proposed method is easy to apply to the practice.

  19. Optimized Optomechanical Micro-Cantilever Array for Uncooled Infrared Imaging

    Institute of Scientific and Technical Information of China (English)

    DONG Feng-Liang; ZHANG Qing-Chuan; CHEN Da-Peng; MIAO Zheng-Yu; XIONG Zhi-Ming; GUO Zhe-Ying; LI Chao-Bo; JIAO Bin-Bin; WU Xiao-Ping

    2007-01-01

    We present a new substrate-free bimaterial cantilever array made of SiNx and Au for an uncooled microoptomechanical infrared imaging device.Each cantilever element has an optimized deformation magnification structure.A 160×160 array with a 120μm×120μm pitch is fabricared and an optical readout is used to collectively measure deflections of all microcantilevers in the array.Tharmal images of room-temperature objects with higher spatial resolution have been obtained and the noise-equivalent temperature difference of the fabricated focal plane arrays is giyen statistically and is measured to be about 270mK.

  20. Coupled-oscillator based active-array antennas

    CERN Document Server

    Pogorzelski, Ronald J

    2012-01-01

    Describing an innovative approach to phased-array control in antenna design This book explores in detail phased-array antennas that use coupled-oscillator arrays, an arrangement featuring a remarkably simple beam steering control system and a major reduction in complexity compared with traditional methods of phased-array control. It brings together in one convenient, self-contained volume the many salient research results obtained over the past ten to fifteen years in laboratories around the world, including the California Institute of Technology's Jet Propulsion Laboratory.

  1. A Real-time Modeling of Photovoltaic Array

    Institute of Scientific and Technical Information of China (English)

    王魏; 李柠; 李少远

    2012-01-01

    This paper mainly aims at the modeling problem of the photovoltaic (PV) array with a 30 kW PV grid-connected generation system. An iterative method for the time-varying parameters is proposed to model a plant of PV array. The relationship of PV cell and PV array is obtained and the solution for PV array model is unique. The PV grid-connected generation system is used to demonstrate the effectiveness of the proposed method by comparing the calculated values with the actual output of the system.

  2. Surface optical Bloch oscillations in semi-infinite waveguide arrays.

    Science.gov (United States)

    Chremmos, I D; Efremidis, N K

    2012-06-01

    We predict that surface optical Bloch oscillations can exist in semi-infinite waveguide arrays with a linear index variation, if the array parameters close to the boundary are appropriately perturbed. The perturbation is such that the surface states obtain the Wannier-Stark ladder eigenvalues of the unperturbed infinite array. The number of waveguides, whose parameters need to be controlled, decreases with increasing ratio of index gradient over coupling. The configuration can find applications as a "matched" termination of waveguide arrays to eliminate the distortion of Bloch oscillations due to reflection on the boundaries.

  3. Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA.

    Science.gov (United States)

    Regan, S P; Goncharov, V N; Igumenshchev, I V; Sangster, T C; Betti, R; Bose, A; Boehly, T R; Bonino, M J; Campbell, E M; Cao, D; Collins, T J B; Craxton, R S; Davis, A K; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Frenje, J A; Froula, D H; Gatu Johnson, M; Glebov, V Yu; Harding, D R; Hohenberger, M; Hu, S X; Jacobs-Perkins, D; Janezic, R; Karasik, M; Keck, R L; Kelly, J H; Kessler, T J; Knauer, J P; Kosc, T Z; Loucks, S J; Marozas, J A; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Myatt, J F; Obenschain, S P; Petrasso, R D; Radha, P B; Rice, B; Rosenberg, M J; Schmitt, A J; Schmitt, M J; Seka, W; Shmayda, W T; Shoup, M J; Shvydky, A; Skupsky, S; Solodov, A A; Stoeckl, C; Theobald, W; Ulreich, J; Wittman, M D; Woo, K M; Yaakobi, B; Zuegel, J D

    2016-07-01

    A record fuel hot-spot pressure P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

  4. Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA.

    Science.gov (United States)

    Regan, S P; Goncharov, V N; Igumenshchev, I V; Sangster, T C; Betti, R; Bose, A; Boehly, T R; Bonino, M J; Campbell, E M; Cao, D; Collins, T J B; Craxton, R S; Davis, A K; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Frenje, J A; Froula, D H; Gatu Johnson, M; Glebov, V Yu; Harding, D R; Hohenberger, M; Hu, S X; Jacobs-Perkins, D; Janezic, R; Karasik, M; Keck, R L; Kelly, J H; Kessler, T J; Knauer, J P; Kosc, T Z; Loucks, S J; Marozas, J A; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Myatt, J F; Obenschain, S P; Petrasso, R D; Radha, P B; Rice, B; Rosenberg, M J; Schmitt, A J; Schmitt, M J; Seka, W; Shmayda, W T; Shoup, M J; Shvydky, A; Skupsky, S; Solodov, A A; Stoeckl, C; Theobald, W; Ulreich, J; Wittman, M D; Woo, K M; Yaakobi, B; Zuegel, J D

    2016-07-01

    A record fuel hot-spot pressure P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance. PMID:27447511

  5. Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Meezan, N. B., E-mail: meezan1@llnl.gov; Hopkins, L. F. Berzak; Pape, S. Le; Divol, L.; MacKinnon, A. J.; Döppner, T.; Ho, D. D.; Jones, O. S.; Khan, S. F.; Ma, T.; Milovich, J. L.; Pak, A. E.; Ross, J. S.; Thomas, C. A.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Field, J. E.; Haan, S. W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); and others

    2015-06-15

    High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 10{sup 15} neutrons, 40% of the 1D simulated yield.

  6. Truncated States Obtained by Iteration

    Institute of Scientific and Technical Information of China (English)

    W.B.Cardoso; N.G.de Almeida

    2008-01-01

    We introduce the concept of truncated states obtained via iterative processes(TSI)and study its statistical features,making an analogy with dynamical systems theory(DST).As a specific example,we have studied TSI for the doubring and the logistic functions,which are standard functions in studying chaos.TSI for both the doubling and logistic functions exhibit certain similar patterns when their statistical features are compared from the point of view of DST.

  7. FEL phased array configurations

    Science.gov (United States)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  8. Wireless Josephson Junction Arrays

    Science.gov (United States)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.

  9. The transient scattering mechanism of dipole array with reflector

    Institute of Scientific and Technical Information of China (English)

    Zhang Xue-Qin; Wang Jun-Hong; Li Zeng-Rui

    2008-01-01

    The transient backscattering mechanisms of a dipole array with reflector have been investigated from different aspects:time-domain,frequency-domain,and combined time-frequency domain,using 4×8 dipole arrays with reflector as an example.The data of scattering from the arrays under the incidence of Gaussian pulses are obtained by finite differential time domain method.The influences of the array structural parameters,incident wave parameters,and incident angles on the waveforms,spectrum,and time-frequency representations of the backseattered fields of the arrays are analysed and conclusions are drawn.From these characteristics and conclusions,it is possible to deduce the array structure inversely from the backscattered field.

  10. Photovoltaic array performance model.

    Energy Technology Data Exchange (ETDEWEB)

    Kratochvil, Jay A.; Boyson, William Earl; King, David L.

    2004-08-01

    This document summarizes the equations and applications associated with the photovoltaic array performance model developed at Sandia National Laboratories over the last twelve years. Electrical, thermal, and optical characteristics for photovoltaic modules are included in the model, and the model is designed to use hourly solar resource and meteorological data. The versatility and accuracy of the model has been validated for flat-plate modules (all technologies) and for concentrator modules, as well as for large arrays of modules. Applications include system design and sizing, 'translation' of field performance measurements to standard reporting conditions, system performance optimization, and real-time comparison of measured versus expected system performance.

  11. Soldered solar arrays

    Science.gov (United States)

    Allen, H. C.

    1982-06-01

    The ability of soldered interconnects to withstand a combination of long life and severe environmental conditions was investigated. Improvements in joint life from the use of solder mixes appropriate to low temperature conditons were studied. Solder samples were placed in a 150 C oven for 5 weeks (= 12 yr at 80 C, or 24 at 70 C according to Arrhenius's rule). Conventional and high solder melting point array samples underwent 1000 thermal cycles between -186 and 100 C. Results show that conventional and lead rich soldered arrays can survive 10 yr geostationary orbit missions.

  12. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  13. Dynamic response of towed line array

    Institute of Scientific and Technical Information of China (English)

    YANG Bing-ka; ZHU Ke-qiang; ZHU Yan-jie; QIN Dao-wu

    2013-01-01

    Three-dimensional motion equations with consideration of the bending and torsional effects of a marine towed cable system under large elastic deformation conditions are formulated using the lumped parameter model.The lumped mass model is used to simulate a circular maneuver of a towed horizontal array that was first presented by Ablow.The results of this paper are in a good agreement with those obtained by finite difference schemes,and the minimum depth is closer to the experimental result.Although the calculations take more computation time,the lumped mass model is a good method,which can also be used to solve problems of towed line array,especially multi-branched towed line array,because of its flexibility.

  14. A millisecond pulsar timing array

    Science.gov (United States)

    Hobbs, George; Manchester, Dick; Sarkissian, John; Bailes, Matthew; Bhat, Ramesh; Keith, Michael; Burke-Spolaor, Sarah; Coles, William; van Straten, Willem; Ravi, Vikram; Oslowski, Stefan; Khoo, Jonathan; Shannon, Ryan; Wang, Jingbo; Levin, Yuri

    2013-10-01

    The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. There are many secondary goals, some astrophysical and some instrumental/technique oriented. Achievement of these ambitious primary goals requires frequent observations of at least 20 MSPs at two or preferably three widely spaced frequencies over several years. We wish to continue observing the PPTA sample at intervals of 2-3 weeks using both the 10/50cm and Multibeam receivers. The digital filterbanks (PDFB3, PDFB4) and the baseband systems (CPSR2; APSR) are used for data recording. With the new instruments and development of an efficient pipeline processing system, we have achieved the world's best pulsar timing precision. We are collaborating with the European and North American pulsar timing array groups (EPTA and NANOGrav, respectively) to obtain more frequent observations and a larger pulsar sample. Because of the high sensitivity and wide bandwidths required, RFI mitigation is an important part of the project. We request continuing status for this project.

  15. Array Theory and Nial

    DEFF Research Database (Denmark)

    Falster, Peter; Jenkins, Michael

    1999-01-01

    This report is the result of collaboration between the authors during the first 8 months of 1999 when M. Jenkins was visiting professor at DTU. The report documents the development of a tool for the investigation of array theory concepts and in particular presents various approaches to choose pri...

  16. The Murchison Widefield Array

    NARCIS (Netherlands)

    Mitchell, Daniel A.; Greenhill, Lincoln J.; Ord, Stephen M.; Bernardi, Gianni

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imagin

  17. Cantilever array sensors

    Directory of Open Access Journals (Sweden)

    Hans Peter Lang

    2005-04-01

    Full Text Available Miniaturized microfabricated sensors have enormous potential in gas detection, biochemical analysis, medical applications, quality and process control, and product authenticity issues. Here, we highlight an ultrasensitive mechanical way of converting (bio-chemical or physical processes into a recordable signal using microfabricated cantilever arrays.

  18. Bandwidth Reconfigurable Metamaterial Arrays

    Directory of Open Access Journals (Sweden)

    Nathanael J. Smith

    2014-01-01

    Full Text Available Metamaterial structures provide innovative ways to manipulate electromagnetic wave responses to realize new applications. This paper presents a conformal wideband metamaterial array that achieves as much as 10 : 1 continuous bandwidth. This was done by using interelement coupling to concurrently achieve significant wave slow-down and cancel the inductance stemming from the ground plane. The corresponding equivalent circuit of the resulting array is the same as that of classic metamaterial structures. In this paper, we present a wideband Marchand-type balun with validation measurements demonstrating the metamaterial (MTM array’s bandwidth from 280 MHz to 2800 MHz. Bandwidth reconfiguration of this class of array is then demonstrated achieving a variety of band-pass or band-rejection responses within its original bandwidth. In contrast with previous bandwidth and frequency response reconfigurations, our approach does not change the aperture’s or ground plane’s geometry, nor does it introduce external filtering structures. Instead, the new responses are realized by making simple circuit changes into the balanced feed integrated with the wideband MTM array. A variety of circuit changes can be employed using MEMS switches or variable lumped loads within the feed and 5 example band-pass and band-rejection responses are presented. These demonstrate the potential of the MTM array’s reconfiguration to address a variety of responses.

  19. The Allen Telescope Array

    Science.gov (United States)

    Bower, Geoffrey C.; Allen Telescope Array Team

    2010-01-01

    The ATA is a 42-element centimeter wavelength array located in Hat Creek, California and jointly operated by UC Berkeley Radio Astronomy Laboratory and the SETI Institute. Since the ATA dedication in Fall 2007, activities have been focused on commissioning the array, retrofitting a handful of components including the feed, developing an operations model, creation of pipeline processing for correlator imaging data, early science observations, and launching of the major surveys for which the telescope was built. The retrofit of the feed improves feed mechanical robustness as well as high frequency performance. Science programs launched include imaging radio transient and static sky surveys (ATATS and PiGSS), commensal SETI and transient surveys of the Galactic Center, targeted SETI observations of nearby stars, the Fly's Eye transient survey, broadband spectra of nearby star-forming galaxies, polarimetric observations of bright radio sources, observations of hydrogen in nearby galaxies and galaxy groups, molecular line observations in the Galaxy, and observations of Jupiter and the Moon. The baseline Square Kilometer Array (SKA) design, a large-N-small-diameter (LNSD) array with wide-band single-pixel feeds and an offset Gregorian antenna, bears a strong resemblance to the ATA. Additional ATA contributions to the SKA include configuration studies for LNSD arrays, the use of fiber optics for broadband data transmission, the use of flexible FPGA-based digital electronics, passive cooling of antennas, and implementation of commensal observing modes. The ATA is currently used for exploration of calibration and imaging algorithms necessary for the SKA. I will summarize current technical status and performance, the results from early science and surveys, and ATA contributions to SKA development.

  20. Radiation symmetry control for inertial confinement fusion capsule implosions in double Z-pinch hohlraums on Z

    International Nuclear Information System (INIS)

    The double Z-pinch hohlraum high-yield concept [Hammer et al., Phys. Plasmas 6, 2129 (1999)] utilizes two 63-MA Z pinches to heat separate primary hohlraums at either end of a secondary hohlraum containing the cryogenic fusion capsule. Recent experiments on the Z accelerator [Spielman et al., Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories have developed an advanced single-sided power feed, double Z-pinch load to study radiation symmetry and pinch power balance using implosion capsules [Cuneo et al., Phys. Rev. Lett. 88, 215004 (2002)]. Point-projection x-ray imaging with the Z-Beamlet Laser mapped the trajectory and distortion of 2-mm diameter plastic ablator capsules. Using the backlit capsule distortion as a symmetry diagnostic, the ability to predictably tune symmetry at the 2 Legendre mode asymmetry coefficient over a range of ±6% (±2% considering points nearest the optimum) was achieved by varying the length of the cylindrical secondary hohlraum containing the capsule, in agreement with viewfactor and radiation-hydrodynamics simulations

  1. High performance capsule implosions driven by the Z-pinch dynamic hohlraum

    International Nuclear Information System (INIS)

    The Z-pinch dynamic hohlraum (ZPDH) is a high-power x-ray source that has been used in a variety of high energy-density experiments including inertial confinement fusion (ICF) studies. The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH2 foam converter launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. Through time-gated pinhole camera measurements, the mean shock speed is measured from 28 experiments to be 326 ± 4 μm ns-1 with a shot-to-shot standard deviation of 7%. Broad-band x-ray measurements indicate that the shot-to-shot reproducibility in the power emission and pulse-shape of the source shock is 40 kJ of x-ray energy, within a factor of 4 of the energy believed sufficient for ICF ignition. The capsule types imploded by the ZPDH have evolved over four years culminating in a design that produces record indirect-drive DD thermonuclear neutron yields of up to 3.5E11

  2. Towards Truly Boolean Arrays in Data-Parallel Array Processing

    NARCIS (Netherlands)

    C. Grelck; H. Luyat

    2013-01-01

    We investigate several dense bit-wise implementations of Boolean arrays in the context of the functional data-parallel array programming language SAC. A particular problem arises in compiler or directive based parallelisation as the scheduling of loops over Boolean arrays is unaware of the restricte

  3. Concurrent array-based queue

    Energy Technology Data Exchange (ETDEWEB)

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-01-06

    According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.

  4. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  5. Timed arrays wideband and time varying antenna arrays

    CERN Document Server

    Haupt, Randy L

    2015-01-01

    Introduces timed arrays and design approaches to meet the new high performance standards The author concentrates on any aspect of an antenna array that must be viewed from a time perspective. The first chapters briefly introduce antenna arrays and explain the difference between phased and timed arrays. Since timed arrays are designed for realistic time-varying signals and scenarios, the book also reviews wideband signals, baseband and passband RF signals, polarization and signal bandwidth. Other topics covered include time domain, mutual coupling, wideband elements, and dispersion. The auth

  6. Microreactor Array Device

    Science.gov (United States)

    Wiktor, Peter; Brunner, Al; Kahn, Peter; Qiu, Ji; Magee, Mitch; Bian, Xiaofang; Karthikeyan, Kailash; Labaer, Joshua

    2015-03-01

    We report a device to fill an array of small chemical reaction chambers (microreactors) with reagent and then seal them using pressurized viscous liquid acting through a flexible membrane. The device enables multiple, independent chemical reactions involving free floating intermediate molecules without interference from neighboring reactions or external environments. The device is validated by protein expressed in situ directly from DNA in a microarray of ~10,000 spots with no diffusion during three hours incubation. Using the device to probe for an autoantibody cancer biomarker in blood serum sample gave five times higher signal to background ratio compared to standard protein microarray expressed on a flat microscope slide. Physical design principles to effectively fill the array of microreactors with reagent and experimental results of alternate methods for sealing the microreactors are presented.

  7. The Submillimeter Array Polarimeter

    OpenAIRE

    Marrone, Daniel P.; Rao, Ramprasad

    2008-01-01

    We describe the Submillimeter Array (SMA) Polarimeter, a polarization converter and feed multiplexer installed on the SMA. The polarimeter uses narrow-band quarter-wave plates to generate circular polarization sensitivity from the linearly-polarized SMA feeds. The wave plates are mounted in rotation stages under computer control so that the polarization handedness of each antenna is rapidly selectable. Positioning of the wave plates is found to be highly repeatable, better than 0.2 degrees. A...

  8. The Murchison Widefield Array

    CERN Document Server

    Mitchell, Daniel A; Ord, Stephen M; Bernardi, Gianni; Wayth, Randall B; Edgar, Richard G; Clark, Michael A; Dal, Kevin; Pfister, Hanspeter; Gleadow, Stewart J; Arcus, W; Briggs, F H; Benkevitch, L; Bowman, J D; Bunton, J D; Burns, S; Cappallo, R J; Corey, B E; de Oliveira-Costa, A; Desouza, L; Doeleman, S S; Derome, M F; Emrich, D; Glossop, M; Goeke, R; Krishna, M R Gopala; Hazelton, B; Herne, D E; Hewitt, J N; Kamini, P A; Kaplan, D L; Kasper, J C; Kincaid, B B; Kocz, J; Kowald, E; Kratzenberg, E; Kumar, D; Lonsdale, C J; Lynch, M J; Madhavi, S; Matejek, M; McWhirter, S R; Morales, M F; Morgan, E; Oberoi, D; Pathikulangara, J; Prabu, T; Rogers, A; Salah, J E; Sault, R J; Shankar, N Udaya; Srivani, K S; Stevens, J; Tingay, S J; Vaccarella, A; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imaging software, which is currently being used to process an FM-band survey of the entire southern sky.

  9. The Cherenkov Telescope Array

    OpenAIRE

    Bigongiari, Ciro

    2016-01-01

    The Cherenkov Telescope Array (CTA) is planned to be the next generation ground based observatory for very high energy (VHE) gamma-ray astronomy. Gamma-rays provide a powerful insight into the non-thermal universe and hopefully a unique probe for new physics. Imaging Cherenkov telescopes have already discovered more than 170 VHE gamma-ray emitters providing plentiful of valuable data and clearly demonstrating the power of this technique. In spite of the impressive results there are indication...

  10. Solar collector array

    Science.gov (United States)

    Hall, John Champlin; Martins, Guy Lawrence

    2015-09-06

    A method and apparatus for efficient manufacture, assembly and production of solar energy. In one aspect, the apparatus may include a number of modular solar receiver assemblies that may be separately manufactured, assembled and individually inserted into a solar collector array housing shaped to receive a plurality of solar receivers. The housing may include optical elements for focusing light onto the individual receivers, and a circuit for electrically connecting the solar receivers.

  11. Supersymetric laser arrays

    OpenAIRE

    El-Ganainy, Ramy; Ge, Li; Khajavikhan, Mercedeh; Christodoulides, Demetrios

    2015-01-01

    We introduce the concept of supersymmetric laser arrays that consists of a main optical lattice and its superpartner structure, and we investigate the onset of their lasing oscillations. Due to the coupling of the two constituent lattices, their degenerate optical modes form doublets, while the extra mode associated with unbroken supersymmetry forms a singlet state. Singlet lasing can be achieved for a wide range of design parameters either by introducing stronger loss in the partner lattice ...

  12. The Square Kilometre Array

    OpenAIRE

    Lazio, Joseph

    2009-01-01

    The Square Kilometre Array (SKA) is intended as the next-generation radio telescope and will address fundamental questions in astrophysics, physics, and astrobiology. The international science community has developed a set of Key Science Programs: (1) Emerging from the Dark Ages and the Epoch of Reionization, (2) Galaxy Evolution, Cosmology, and Dark Energy, (3) The Origin and Evolution of Cosmic Magnetism, (4) Strong Field Tests of Gravity Using Pulsars and Black Holes, and (5) The Cradle of...

  13. Photovoltaic cell array

    Science.gov (United States)

    Eliason, J. T. (Inventor)

    1976-01-01

    A photovoltaic cell array consisting of parallel columns of silicon filaments is described. Each fiber is doped to produce an inner region of one polarity type and an outer region of an opposite polarity type to thereby form a continuous radial semi conductor junction. Spaced rows of electrical contacts alternately connect to the inner and outer regions to provide a plurality of electrical outputs which may be combined in parallel or in series.

  14. The TALE Infill Array

    Science.gov (United States)

    Bergman, Douglas

    2009-05-01

    The TALE Infill Array in conjunction with the TALE Tower Detector will provide hybrid coverage of the cosmic ray energy spectrum down to 3x10^16 eV. It will consist of about 100, two square meter scintillators on the surface spaced at 400 m; and 24 buried twelve square meter scintillators. The combination of surface and underground detectors will allow for the determination of the muon content of showers and thus give a handle on cosmic ray composition.

  15. Experimental study on imploding characteristics of wire-array Z pinches on Qiangguang-1 facility

    Institute of Scientific and Technical Information of China (English)

    Wang Zhen; Xu Rong-Kun; Yang Jian-Lun; Hua Xin-Sheng; Li Lin-Bo; Xu Ze-Ping; Ning Jia-Min; Song Feng-Jun

    2007-01-01

    To investigate the imploding characteristics of cylindrical wire array,experiments with load current varying from 1.5MA to 1.7MA were carried out on the Qiangguang-1 facility.The complicated temporal-spatial distribution of x-ray radiation was measured by the one-dimensional (1D) x-ray imaging system.Other diagnostic equipments including the x-ray power meter(XRPM) and the time-integrated pinhole camera were used to record time-resolved x-ray power pulse and pinhole x-ray images.Analysis shows that the fast leading edge of the local x-ray radiation pulse is of primary importance in sharpening x-ray power pulse rather than the temporal synchrony and the spatial uniformity of implosion.Experimental results indicated that the better axial imploding synchrony,the faster the increase of X-ray power for an array consisting of 32 tungsten wires of 5μm diameter than for the others,and the higher the x-ray radiation power with maximal convergence ratio (r0/r1) of 10.5.A 'zipper-like' effect of x-ray radiation extending from the cathode Was also observed.

  16. Spaceborne Processor Array

    Science.gov (United States)

    Chow, Edward T.; Schatzel, Donald V.; Whitaker, William D.; Sterling, Thomas

    2008-01-01

    A Spaceborne Processor Array in Multifunctional Structure (SPAMS) can lower the total mass of the electronic and structural overhead of spacecraft, resulting in reduced launch costs, while increasing the science return through dynamic onboard computing. SPAMS integrates the multifunctional structure (MFS) and the Gilgamesh Memory, Intelligence, and Network Device (MIND) multi-core in-memory computer architecture into a single-system super-architecture. This transforms every inch of a spacecraft into a sharable, interconnected, smart computing element to increase computing performance while simultaneously reducing mass. The MIND in-memory architecture provides a foundation for high-performance, low-power, and fault-tolerant computing. The MIND chip has an internal structure that includes memory, processing, and communication functionality. The Gilgamesh is a scalable system comprising multiple MIND chips interconnected to operate as a single, tightly coupled, parallel computer. The array of MIND components shares a global, virtual name space for program variables and tasks that are allocated at run time to the distributed physical memory and processing resources. Individual processor- memory nodes can be activated or powered down at run time to provide active power management and to configure around faults. A SPAMS system is comprised of a distributed Gilgamesh array built into MFS, interfaces into instrument and communication subsystems, a mass storage interface, and a radiation-hardened flight computer.

  17. Array processor architecture

    Science.gov (United States)

    Barnes, George H. (Inventor); Lundstrom, Stephen F. (Inventor); Shafer, Philip E. (Inventor)

    1983-01-01

    A high speed parallel array data processing architecture fashioned under a computational envelope approach includes a data base memory for secondary storage of programs and data, and a plurality of memory modules interconnected to a plurality of processing modules by a connection network of the Omega gender. Programs and data are fed from the data base memory to the plurality of memory modules and from hence the programs are fed through the connection network to the array of processors (one copy of each program for each processor). Execution of the programs occur with the processors operating normally quite independently of each other in a multiprocessing fashion. For data dependent operations and other suitable operations, all processors are instructed to finish one given task or program branch before all are instructed to proceed in parallel processing fashion on the next instruction. Even when functioning in the parallel processing mode however, the processors are not locked-step but execute their own copy of the program individually unless or until another overall processor array synchronization instruction is issued.

  18. Mixed Frequency Ultrasound Phased Array

    Institute of Scientific and Technical Information of China (English)

    香勇; 霍健; 施克仁; 陈以方

    2004-01-01

    A mixed frequency ultrasonic phased array (MPA) was developed to improve the focus, in which the element excitation frequencies are not all the same as in a normal constant frequency phased array. A theoretical model of the mixed frequency phased array based on the interference principle was used to simulate the array's sound distribution. The pressure intensity in the array focal area was enhanced and the scanning area having effective contrast resolution was enlarged. The system is especially useful for high intensity focused ultrasound (HIFU) with more powerful energy and ultrasound imaging diagnostics with improved signal to noise ratios, improved beam forming and more uniform imaging quality.

  19. Nuclear structure and Indian Clover array

    Indian Academy of Sciences (India)

    H C Jain

    2001-07-01

    A brief description of the nuclear structure studies performed with the 14-UD pelletron at TIFR has been presented. The experimental facilities developed for these studies are described. Some of the interesting results obtained for mass 70 to 80 nuclei are presented. The development of a recoil mass spectrometer and an Indian clover array for the study of high spin states in nuclei near drip lines is discussed.

  20. Talbot Effect in Three Waveguide Arrays

    Institute of Scientific and Technical Information of China (English)

    LI Zhi; ZHOU Hai-Feng; YANG Jian-Yi; JIANG Xiao-Qing

    2008-01-01

    By taking the coupling between the non-neighbourhood waveguides into account, the coupling characteristic of three waveguide arrays is analysed. The strong coupling equation of three waveguides is dealt with Laplace transform and LU decomposition. The general field evolution equation is obtained by inversion of the Laplace transform. The results show that the self-imaging conditions (Talbot effect) do not satisfy in general. The theoretical predictions are in good agreement with the BPM simulations.

  1. Discrete Dipole Approximation Aided Design Method for Nanostructure Arrays

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Li; LUO Xian-Gang; DU Chun-Lei

    2007-01-01

    A discrete dipole approximation (DDA) aided design method is proposed to determine the parameters of nanostructure arrays. The relationship between the thickness, period and extinction efficiency of nanostructure arrays for the given shape can be calculated using the DDA. Based on the calculated curves, the main parameters of the nanostructure arrays such as thickness and period can be determined. Using this aided method, a rhombic sliver nanostructure array is designed with the determinant parameters of thickness (40 nm) and period (440 nm).We further fabricate the rhombic sliver nanostructure arrays and testify the character of the extinction spectra.The obtained extinction spectra is within the visible range and the full width at half maximum is 99nm, as is expected.

  2. Time multiplexing super resolution using a Barker-based array.

    Science.gov (United States)

    Ilovitsh, Asaf; Preter, Eyal; Levanon, Nadav; Zalevsky, Zeev

    2015-01-15

    We propose the use of a new encoding mask in order to improve the performance of the conventional time multiplexing super resolution method. The resolution improvement is obtained using a 2D Barker-based array that is placed upon the object and shifted laterally. The Barker-based array is a 2D generalization of the standard 1D Barker code. The Barker-based array has stable autocorrelation sidelobes, making it ideal for the encoding process. A sequence of low resolution images are captured at different positions of the array, and are decoded properly using the same array. After removing the low resolution image from the resulting reconstruction, a high resolution image is established. The proposed method is presented analytically, demonstrated via numerical simulation, and validated by laboratory experiment. PMID:25679834

  3. Characterization of neutron emission from mega-ampere deuterium gas puff Z-pinch at microsecond implosion times

    Science.gov (United States)

    Klir, D.; Shishlov, A. V.; Kokshenev, V. A.; Kubes, P.; Labetsky, A. Yu; Rezac, K.; Cikhardt, J.; Fursov, F. I.; Kovalchuk, B. M.; Kravarik, J.; Kurmaev, N. E.; Ratakhin, N. A.; Sila, O.; Stodulka, J.

    2013-08-01

    Experiments with deuterium (D2) triple shell gas puffs were carried out on the GIT-12 generator at a 3 MA current level and microsecond implosion times. The outer, middle and inner nozzle diameters were 160 mm, 80 mm and 30 mm, respectively. The influence of the mass of deuterium shells on neutron emission times, neutron yields and neutron energy spectra was studied. The injected linear mass of deuterium varied between 50 and 255 µg cm-1. Gas puffs imploded onto the axis before the peak of generator current at 700-1100 ns. Most of the neutrons were emitted during the second neutron pulse after the development of instabilities. Despite higher currents, heavier gas puffs produced lower neutron yields. Optimal mass and a short time delay between the valve opening and the generator triggering were more important than the better coincidence of stagnation with peak current. The peak neutron yield from D(d, n)3He reactions reached 3 × 1011 at 2.8 MA current, 90 µg cm-1 injected linear mass and 37 mm anode-cathode gap. In the case of lower mass shots, a large number of 10 MeV neutrons were produced either by secondary DT reactions or by DD reactions of deuterons with energies above 7 MeV. The average neutron yield ratio Y>10 MeV/Y2.5 MeV reached (6 ± 3) × 10-4. Such a result can be explained by a power law distribution for deuterons as \\rmd N_d/\\rmd E_d\\propto E_d^{-3} . The optimization of a D2 gas puff Z-pinch and similarities to a plasma focus and its drive parameter are described.

  4. Isolating and quantifying cross-beam energy transfer in direct-drive implosions on OMEGA and the National Ignition Facility

    Science.gov (United States)

    Davis, A. K.; Cao, D.; Michel, D. T.; Hohenberger, M.; Edgell, D. H.; Epstein, R.; Goncharov, V. N.; Hu, S. X.; Igumenshchev, I. V.; Marozas, J. A.; Maximov, A. V.; Myatt, J. F.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Froula, D. H.

    2016-05-01

    The angularly resolved mass ablation rates and ablation-front trajectories for Si-coated CH targets were measured in direct-drive inertial confinement fusion experiments to quantify cross-beam energy transfer (CBET) while constraining the hydrodynamic coupling. A polar-direct-drive laser configuration, where the equatorial laser beams were dropped and the polar beams were repointed from a symmetric direct-drive configuration, was used to limit CBET at the pole while allowing it to persist at the equator. The combination of low- and high-CBET conditions observed in the same implosion allowed for the effects of CBET on the ablation rate and ablation pressure to be determined. Hydrodynamic simulations performed without CBET agreed with the measured ablation rate and ablation-front trajectory at the pole of the target, confirming that the CBET effects on the pole are small. The simulated mass ablation rates and ablation-front trajectories were in excellent agreement with the measurements at all angles when a CBET model based on Randall's equations [C. J. Randall et al., Phys. Fluids 24, 1474 (1981)] was included into the simulations with a multiplier on the CBET gain factor. These measurements were performed on OMEGA and at the National Ignition Facility to access a wide range of plasma conditions, laser intensities, and laser beam geometries. The presence of the CBET gain multiplier required to match the data in all of the configurations tested suggests that additional physics effects, such as intensity variations caused by diffraction, polarization effects, or shortcomings of extending the 1-D Randall model to 3-D, should be explored to explain the differences in observed and predicted drive.

  5. Numerical simulations of annular wire-array z-pinches in (x,y), (r,{theta}), and (r,z) geometries

    Energy Technology Data Exchange (ETDEWEB)

    Marder, B.M.; Sanford, T.W.L.; Allshouse, G.O.

    1997-12-01

    The Total Immersion PIC (TIP) code has been used in several two-dimensional geometries to understand better the measured dynamics of annular, aluminum wire-array z-pinches. The areas investigated include the formation of the plasma sheath from current-induced individual wire explosions, the effects of wire number and symmetry on the implosion dynamics, and the dependence of the Rayleigh-Taylor instability growth on initial sheath thickness. A qualitative change in the dynamics with increasing wire number was observed, corresponding to a transition between a z-pinch composed of non-merging, self-pinching individual wires, and one characterized by the rapid formation and subsequent implosion of a continuous plasma sheath. A sharp increase in radiated power with increasing wire number has been observed experimentally near this calculated transition. Although two-dimensional codes have correctly simulated observed power pulse durations, there are indications that three dimensional effects are important in understanding the actual mechanism by which these pulse lengths are produced.

  6. Adaptive and mobile ground sensor array.

    Energy Technology Data Exchange (ETDEWEB)

    Holzrichter, Michael Warren; O' Rourke, William T.; Zenner, Jennifer; Maish, Alexander B.

    2003-12-01

    The goal of this LDRD was to demonstrate the use of robotic vehicles for deploying and autonomously reconfiguring seismic and acoustic sensor arrays with high (centimeter) accuracy to obtain enhancement of our capability to locate and characterize remote targets. The capability to accurately place sensors and then retrieve and reconfigure them allows sensors to be placed in phased arrays in an initial monitoring configuration and then to be reconfigured in an array tuned to the specific frequencies and directions of the selected target. This report reviews the findings and accomplishments achieved during this three-year project. This project successfully demonstrated autonomous deployment and retrieval of a payload package with an accuracy of a few centimeters using differential global positioning system (GPS) signals. It developed an autonomous, multisensor, temporally aligned, radio-frequency communication and signal processing capability, and an array optimization algorithm, which was implemented on a digital signal processor (DSP). Additionally, the project converted the existing single-threaded, monolithic robotic vehicle control code into a multi-threaded, modular control architecture that enhances the reuse of control code in future projects.

  7. Performance Analysis of ICA in Sensor Array

    Science.gov (United States)

    Cai, Xin; Wang, Xiang; Huang, Zhitao; Wang, Fenghua

    2016-01-01

    As the best-known scheme in the field of Blind Source Separation (BSS), Independent Component Analysis (ICA) has been intensively used in various domains, including biomedical and acoustics applications, cooperative or non-cooperative communication, etc. While sensor arrays are involved in most of the applications, the influence on the performance of ICA of practical factors therein has not been sufficiently investigated yet. In this manuscript, the issue is researched by taking the typical antenna array as an illustrative example. Factors taken into consideration include the environment noise level, the properties of the array and that of the radiators. We analyze the analytic relationship between the noise variance, the source variance, the condition number of the mixing matrix and the optimal signal to interference-plus-noise ratio, as well as the relationship between the singularity of the mixing matrix and practical factors concerned. The situations where the mixing process turns (nearly) singular have been paid special attention to, since such circumstances are critical in applications. Results and conclusions obtained should be instructive when applying ICA algorithms on mixtures from sensor arrays. Moreover, an effective countermeasure against the cases of singular mixtures has been proposed, on the basis of previous analysis. Experiments validating the theoretical conclusions as well as the effectiveness of the proposed scheme have been included. PMID:27164100

  8. Performance Analysis of ICA in Sensor Array

    Directory of Open Access Journals (Sweden)

    Xin Cai

    2016-05-01

    Full Text Available As the best-known scheme in the field of Blind Source Separation (BSS, Independent Component Analysis (ICA has been intensively used in various domains, including biomedical and acoustics applications, cooperative or non-cooperative communication, etc. While sensor arrays are involved in most of the applications, the influence on the performance of ICA of practical factors therein has not been sufficiently investigated yet. In this manuscript, the issue is researched by taking the typical antenna array as an illustrative example. Factors taken into consideration include the environment noise level, the properties of the array and that of the radiators. We analyze the analytic relationship between the noise variance, the source variance, the condition number of the mixing matrix and the optimal signal to interference-plus-noise ratio, as well as the relationship between the singularity of the mixing matrix and practical factors concerned. The situations where the mixing process turns (nearly singular have been paid special attention to, since such circumstances are critical in applications. Results and conclusions obtained should be instructive when applying ICA algorithms on mixtures from sensor arrays. Moreover, an effective countermeasure against the cases of singular mixtures has been proposed, on the basis of previous analysis. Experiments validating the theoretical conclusions as well as the effectiveness of the proposed scheme have been included.

  9. Linear antenna array optimization using flower pollination algorithm.

    Science.gov (United States)

    Saxena, Prerna; Kothari, Ashwin

    2016-01-01

    Flower pollination algorithm (FPA) is a new nature-inspired evolutionary algorithm used to solve multi-objective optimization problems. The aim of this paper is to introduce FPA to the electromagnetics and antenna community for the optimization of linear antenna arrays. FPA is applied for the first time to linear array so as to obtain optimized antenna positions in order to achieve an array pattern with minimum side lobe level along with placement of deep nulls in desired directions. Various design examples are presented that illustrate the use of FPA for linear antenna array optimization, and subsequently the results are validated by benchmarking along with results obtained using other state-of-the-art, nature-inspired evolutionary algorithms such as particle swarm optimization, ant colony optimization and cat swarm optimization. The results suggest that in most cases, FPA outperforms the other evolutionary algorithms and at times it yields a similar performance. PMID:27066339

  10. High Power Fiber Bundle Array Coupled LDA Module

    Institute of Scientific and Technical Information of China (English)

    QU Zhou; LIU Yang; ZHAO Chong-guang; WANG Ji; YIN Hong-he; WANG Li-jun

    2006-01-01

    An optical fiber bundle array coupling module with high output power is presented in this paper. The device integrated the coupling technique of the high power laser diode array (LDA) and the micro-ball lenses fiber array. This module can efficiently couple the output laser of the LDA into 19 fibers array with micro-ball lens endsurface. The difference of the couple efficiency between the flat-end fiber and micro-ball-end fiber is discussed.The micro-ball lenses fiber array made of 19 fibers have the same fiber core diameter of 200 μm, and then the endsurfaces of 19 fibers are fused to 19 micro-ball lenses. The micro-ball lenses fiber array are fixed precisely in the neighborhood on the V-grooves, and the fiber array has the same arrange period with the semiconductor laser units of LDA. This configuration of micro-ball lens fiber array can greatly reduce the divergence of the laser beam from all directions, and a very efficient laser beam homogenizer and shaper are obtained. Finally, high output power of 30.1 W of the fiber coupled LDA is achieved, and the maximal coupling efficiency is >83% with the numeral aperture (NA) of 0.16.

  11. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco;

    2011-01-01

    Permanent magnet arrays are often employed in a broad range of applications: actuators, sensors, drug targeting and delivery systems, fabrication of self-assembled particles, just to name a few. An estimate of the magnetic forces in play between arrays is required to control devices and fabrication...... procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  12. Microplasma generating array

    Energy Technology Data Exchange (ETDEWEB)

    Hopwood, Jeffrey A.; Wu, Chen; Hoskinson, Alan R.; Sonkusale, Sameer

    2016-10-04

    A microplasma generator includes first and second conductive resonators disposed on a first surface of a dielectric substrate. The first and second conductive resonators are arranged in line with one another with a gap defined between a first end of each resonator. A ground plane is disposed on a second surface of the dielectric substrate and a second end of each of the first and second resonators is coupled to the ground plane. A power input connector is coupled to the first resonator at a first predetermined distance from the second end chosen as a function of the impedance of the first conductive resonator. A microplasma generating array includes a number of resonators in a dielectric material substrate with one end of each resonator coupled to ground. A micro-plasma is generated at the non-grounded end of each resonator. The substrate includes a ground electrode and the microplasmas are generated between the non-grounded end of the resonator and the ground electrode. The coupling of each resonator to ground may be made through controlled switches in order to turn each resonator off or on and therefore control where and when a microplasma will be created in the array.

  13. Long-range magnetostatic interactions in arrays of nanowires

    CERN Document Server

    Raposo, V; González, J M; Vázquez, M

    2000-01-01

    Experimental measurements and micromagnetic simulations of the hysteresis loops of arrays of cobalt nanowires are compared here. Arrays of cobalt nanowires (200 nm in diameter) were electrodeposited into the pores of alumina membranes (thickness 60 mu m). Their hysteresis loops along the axial direction of nanowires were measured using vibrating sample magnetometry. Micromagnetic simulations were performed considering dipolar interaction between nanowires leading to similar hysteresis loops as those obtained experimentally.

  14. Oligonucleotide array outperforms SNP array on formalin-fixed paraffin-embedded clinical samples.

    Science.gov (United States)

    Nasri, Soroush; Anjomshoaa, Ahmad; Song, Sarah; Guilford, Parry; McNoe, Les; Black, Michael; Phillips, Vicky; Reeve, Anthony; Humar, Bostjan

    2010-04-01

    Compromised quality of formalin-fixed paraffin-embedded (FFPE)-derived DNA has compounded the use of archival specimens for array-based genomic studies. Recent technological advances have led to first successes in this field; however, there is currently no general agreement on the most suitable platform for the array-based analysis of FFPE DNA. In this study, FFPE and matched fresh-frozen (FF) specimens were separately analyzed with Affymetrix single nucleotide polymorphism (SNP) 6.0 and Agilent 4x44K oligonucleotide arrays to compare the genomic profiles from the two tissue sources and to assess the relative performance of the two platforms on FFPE material. Genomic DNA was extracted from matched FFPE-FF pairs of normal intestinal epithelium from four patients and were applied to the SNP and oligonucleotide platforms according to the manufacturer-recommended protocols. On the Affymetrix platform, a substantial increase in apparent copy number alterations was observed in all FFPE tissues relative to their matched FF counterparts. In contrast, FFPE and matched FF genomic profiles obtained via the Agilent platform were very similar. Both the SNP and the oligonucleotide platform performed comparably on FF material. This study demonstrates that Agilent oligonucleotide array comparative genomic hybridization generates reliable results from FFPE extracted DNA, whereas the Affymetrix SNP-based array seems less suitable for the analysis of FFPE material.

  15. Electrode array for neural stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Wessendorf, Kurt O. (Albuquerque, NM); Okandan, Murat (Edgewood, NM); Stein, David J. (Albuquerque, NM); Yang, Pin (Albuquerque, NM); Cesarano, III, Joseph (Albuquerque, NM); Dellinger, Jennifer (Albuquerque, NM)

    2011-08-16

    An electrode array for neural stimulation is disclosed which has particular applications for use in a retinal prosthesis. The electrode array can be formed as a hermetically-sealed two-part ceramic package which includes an electronic circuit such as a demultiplexer circuit encapsulated therein. A relatively large number (up to 1000 or more) of individually-addressable electrodes are provided on a curved surface of a ceramic base portion the electrode array, while a much smaller number of electrical connections are provided on a ceramic lid of the electrode array. The base and lid can be attached using a metal-to-metal seal formed by laser brazing. Electrical connections to the electrode array can be provided by a flexible ribbon cable which can also be used to secure the electrode array in place.

  16. The Murchison Widefield Array Correlator

    OpenAIRE

    Ord, S. M.; Crosse, B.; Emrich, D.; Pallot, D.; Wayth, R. B.; Clark, M. A.; Tremblay, S. E.; Arcus, W.; Barnes, D; Bell, M.; Bernardi, G.; Bhat, N. D. R.; Bowman, J.D.; Briggs, F.; Bunton, J. D.

    2014-01-01

    The Murchison Widefield Array (MWA) is a Square Kilometre Array (SKA) Precursor. The telescope is located at the Murchison Radio--astronomy Observatory (MRO) in Western Australia (WA). The MWA consists of 4096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Fiel...

  17. Combinatorial aspects of covering arrays

    Directory of Open Access Journals (Sweden)

    Charles J. Colbourn

    2004-11-01

    Full Text Available Covering arrays generalize orthogonal arrays by requiring that t -tuples be covered, but not requiring that the appearance of t -tuples be balanced.Their uses in screening experiments has found application in software testing, hardware testing, and a variety of fields in which interactions among factors are to be identified. Here a combinatorial view of covering arrays is adopted, encompassing basic bounds, direct constructions, recursive constructions, algorithmic methods, and applications.

  18. Laser imprint reduction for the critical-density foam buffered target driven by a relatively strong foot pulse at early stage of laser implosions

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. W., E-mail: li-jiwei@iapcm.ac.cn; He, X. T. [Key Lab of High Energy Density Physics Simulation, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China); Kang, W. [Key Lab of High Energy Density Physics Simulation, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Li, J. H.; Zheng, W. D. [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China)

    2015-12-15

    In order to reduce the effect of laser imprint in direct-drive ignition scheme a low-density foam buffered target has been proposed. This target is driven by a laser pulse with a low-intensity foot at the early stage of implosion, which heats the foam and elongates the thermal conduction zone between the laser absorption region and ablation front, increasing the thermal smoothing effect. In this paper, a relatively strong foot pulse is adopted to irradiate the critical-density foam buffered target. The stronger foot, near 1 × 10{sup 14 }W/cm{sup 2}, is able to drive a radiative shock in the low-density foam, which helps smooth the shock and further reduce the effect of laser imprint. The radiative shock also forms a double ablation front structure between the two ablation fronts to further stabilize the hydrodynamics, achieving the similar results to a target with a high-Z dopant in the ablator. 2D analysis shows that for the critical-density foam buffered target irradiated by the strong foot pulse, the laser imprint can be reduced due to the radiative shock in the foam and an increased thermal smoothing effect. It seems viable for the critical-density foam buffered target to be driven by a relatively strong foot pulse with the goal of reducing the laser imprint and achieving better implosion symmetry in the direct-drive laser fusion.

  19. Numerical Simulation of Single Concrete Framework Implosion Demolition%单榀钢混框架结构内爆法拆除模拟

    Institute of Scientific and Technical Information of China (English)

    李胜林; 王宇涛; 黄明升; 刘凯; 骆之悦

    2012-01-01

    To find out the basic law of the concrete frame structure implosion demolition, the model of single concrete framework of ten stories with five-span frame was constructed by using MAT159 software and adopting separating constrained method to simulate reinforced concrete. First, the gravity balance was executed. Then, the numerical simulation was implemented according to the designed different sequences of implosion demolition. From the results of simulation, the collapsed rules could be achieved. Also the criterion to determine the delay time could be put forward.%为了研究内爆法拆除混凝土框架结构的基本规律,作者使用LS-DYNA中的MAT159本构,采用分离式constrained方法建立钢筋混凝土模型,建立了一个10层5跨的混凝土单榀结构模型,待重力平衡后,采用不同拆除顺序对内爆拆除进行了数值模拟.模拟结果显示了不同内爆方法的倒塌规律,并提出了延期时间的确定原则.

  20. Laser imprint reduction for the critical-density foam buffered target driven by a relatively strong foot pulse at early stage of laser implosions

    International Nuclear Information System (INIS)

    In order to reduce the effect of laser imprint in direct-drive ignition scheme a low-density foam buffered target has been proposed. This target is driven by a laser pulse with a low-intensity foot at the early stage of implosion, which heats the foam and elongates the thermal conduction zone between the laser absorption region and ablation front, increasing the thermal smoothing effect. In this paper, a relatively strong foot pulse is adopted to irradiate the critical-density foam buffered target. The stronger foot, near 1 × 1014 W/cm2, is able to drive a radiative shock in the low-density foam, which helps smooth the shock and further reduce the effect of laser imprint. The radiative shock also forms a double ablation front structure between the two ablation fronts to further stabilize the hydrodynamics, achieving the similar results to a target with a high-Z dopant in the ablator. 2D analysis shows that for the critical-density foam buffered target irradiated by the strong foot pulse, the laser imprint can be reduced due to the radiative shock in the foam and an increased thermal smoothing effect. It seems viable for the critical-density foam buffered target to be driven by a relatively strong foot pulse with the goal of reducing the laser imprint and achieving better implosion symmetry in the direct-drive laser fusion

  1. Observation of asymmetric implosions in indirect-drive ICF associated with changes in laser beam-hohlraum coupling and relevance to mix experiments.

    Science.gov (United States)

    Turner, R. E.; Amendt, P. A.; Landen, O. L.; Wallace, R. J.; Thorp, K.; Pien, G.

    2004-11-01

    Indirect drive ICF experiments were performed on the Omega laser at LLE, both with and without distributed polarization rotators (DPR) in the laser beams. The hohlraums were irradiated with a three-cone beam geometry, experimentally adjusted to produce high-yield implosions with no DPRs installed. X-ray images of the cores of these implosions showed a small but tolerable P2 asymmetry. Similar experiments with DPRs installed produced lower yields, and x-ray images of the imploded cores showed substantially increased P2 asymmetries, suggesting that the shallow-angle cone of beams, which transits through the longest length of plasma and along the shallowest density gradients, had substantially increased absorption compared to the no-DPR case. We will show high magnification (nearly 100x) x-ray images of the cores, along with fusion neutron data. For capsules driven with good symmetry, we show the neutron yield results from capsules whose surfaces have been deliberately roughened by a measured amount, in order to compare to mix models in simulations.

  2. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes....... Numerical results for the capacities are presented....

  3. GERmanium detector array, GERDA

    International Nuclear Information System (INIS)

    The GERmanium Detector Array, GERDA, is designed to search for 'neutrinoless double beta decay' (0ν2β) in 76Ge. The high-purity segmented Ge detectors will be directly submerged and operated in liquid N2 or Ar. The measurement of the half-life time of 0ν2β decay will provide information about the absolute neutrino mass scale and indirectly, the hierarchy. The design goal of GERDA is to reach a sensitivity of 0.2 eV on the effective Majorana neutrino mass (mββ). The GERDA experiment is located in hall A of the Grand Sasso national lab (LNGS) and the construction will start in 2006

  4. Preparation and magnetic properties of Fe0.3Co0.7 nanowire array

    Institute of Scientific and Technical Information of China (English)

    Qin Donghuan; Guo Yun; Li Hulin

    2006-01-01

    Fe0.3Co0.7 nanowire arrays were prepared by electrodeposition into the porous anodic aluminum oxide templates.The change of magnetic characteristic of the array with the diameter and heat treatment was investigated.It was found that the vertical magnetic anisotropy would drop lineally with the increase of the array diameter.Annealing can improve the coercively of the nanowire arrays.Coercivity as high as 3000 Oe was obtained in the sample annealing at 500℃.Magnetic properties of nanowire arrays may be developed to ultra-high-density recording on the quantum disk.

  5. Instability of nanocantilever arrays in electrostatic and van der Waals interactions

    International Nuclear Information System (INIS)

    The structural instability of an array of cantilevers, each of which interacts with two neighbouring beams through electrostatic and van der Waals forces, is studied. Distributed and lumped parameter modelling of the array result in a set of coupled nonlinear boundary value problems and a set of coupled nonlinear equations, respectively. These coupled nonlinear systems are solved numerically for different numbers of beams in the array to obtain the pull-in parameters. The pull-in parameters converge to constant values with an increase in the number of beams in the array. These constants, which are important in the design of cantilever arrays, are compared for the distributed and lumped parameter models.

  6. Fluorescence signals of quantum dots influenced by spatially controlled array structures

    International Nuclear Information System (INIS)

    Fluorescence signals of quantum dots (QDs) influenced by different array structures of gold-coated silicon nanorods (SiNRs) were investigated via experimental observations and two-dimensional (2D) finite element method (FEM) simulations. On the densest gold-coated SiNRs array structure, the highest QD fluorescence quenching rates were observed and on the sparsest array structure, the highest QD fluorescence enhancement rates were observed. By developing a new technique which obtains the optical image of the array structures without losing information about the QD locations, we were able to further investigate how the QD fluorescence is influenced by spatially controlled array structures.

  7. Advances in implosion physics, alternative targets design, and neutron effects on heavy ion fusion reactors

    International Nuclear Information System (INIS)

    The coupling of a new radiation transport (RT) solver with an existing multimaterial fluid dynamics code (ARWEN) using Adaptive Mesh Refinement named DAFNE, has been completed. In addition, improvements were made to ARWEN in order to work properly with the RT code, and to make it user-friendlier, including new treatment of Equations of State, and graphical tools for visualization. The evaluation of the code has been performed, comparing it with other existing RT codes (including the one used in DAFNE, but in the single-grid version). These comparisons consist in problems with real input parameters (mainly opacities and geometry parameters). Important advances in Atomic Physics, Opacity calculations and NLTE atomic physics calculations, with participation in significant experiments in this area, have been obtained. Early published calculations showed that a DTx fuel with a small tritium initial content (xe and to enhance radiation losses, reducing the plasma temperature, Ti. The neutron activation of all natural elements in First Structural Wall (FSW) component of an Inertial Fusion Energy (IFE) reactor for waste management, and the analysis of activation of target debris in NIF-type facilities has been completed. Using an original efficient modeling for pulse activation, the FSW behavior in inertial fusion has been studied. A radiological dose library coupled to the ACAB code is being generated for assessing impact of environmental releases, and atmospheric dispersion analysis from HIF reactors indicate the uncertainty in tritium release parameters. The first recognition of recombination barriers in SiC, modify the understanding of the calculation of displacement per atom, dpa, to quantify the collisional damage. An important analysis has been the confirmation, using Molecular Dynamics (MD) with an astonishing agreement, of the experimental evidence of low-temperature amorphization by damage accumulation in SiC, which could modify extensively its viability as a

  8. Demonstration of 55 +/- 7-Gbar Hot-Spot Pressure in Direct-Drive Layered DT Cryogenic Implosions on OMEGA

    Science.gov (United States)

    Regan, S. P.

    2015-11-01

    Direct-drive ignition target designs for the National Ignition Facility (NIF) require hot-spot pressures in excess of 100 Gbar. Only one-third of the required pressure was inferred in earlier experimental campaigns conducted on the 60-beam, 30-kJ, 351-nm OMEGA laser with direct-drive implosions of layered DT cryogenic targets. Laser and target improvements were implemented on OMEGA to increase the stagnation pressure, including a set of phase plates to increase the laser irradiation uniformity on target and a purified fuel with isotope composition reaching a 50:50 DT ratio. Diagnostic improvements were made for a neutron burnwidth measurement with a 40-ps impulse response and a 16-channel Kirkpatrick-Baez microscope to measure gated (30-ps) x-ray images of the core near peak compression with 6- μm resolution. The inferred volume-averaged, peak pressure in the current campaign almost doubled to 55 +/- 7 Gbar with a neutron yield approaching 5 ×1013 . Further target performance improvements to reach hydrodynamic equivalence to ignition on OMEGA require mitigation of cross-beam energy transfer (CBET), which reduces the laser coupling. A proposed technique to reduce CBET by driving the spherical target with overlapping laser beams having individual focal spots smaller than the outside diameter of the target was investigated. The diameter of the target was discretely varied from 800 to 1000 μm, while the laser focal spot size was kept constant at 820 μm. The larger targets driven with up to 30 kJ of laser energy used dynamic bandwidth reduction, where the smoothing by spectral dispersion (SSD) is only applied to the pickets. The smaller targets driven with 26 kJ of laser energy had SSD on the entire pulse. This talk will summarize the results of this CBET mitigation campaign and describe a path forward to achieve ignition hydro-equivalence on OMEGA. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under

  9. Large scale biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg;

    2009-01-01

    -structured 8 x 8 aperture partition arrays with average aperture diameters of 301 +/- 5 mu m. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane...

  10. Array tomography: semiautomated image alignment.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. Successful array tomography requires that the captured images be properly stacked and aligned, and the software to achieve these ends is freely available. This protocol describes the construction of volumetric image stacks from images of fluorescently labeled arrays for three-dimensional image visualization, analysis, and archiving. PMID:21041400

  11. Tremor as observed by the Array of Arrays in Cascadia

    Science.gov (United States)

    Ghosh, A.; Vidale, J. E.; Creager, K. C.

    2010-12-01

    We are capturing the intimate details of tremor activity in Cascadia with 8 small-aperture seismic arrays in northwestern Washington. The Array of Arrays (AoA) focuses on the tremor-active megathrust, including the area we previously imaged with a solo seismic array in 2008 [Ghosh et al., GRL, 2009, 2010]. Each array consists of 10 to 20 three-component sensors recording in continuous mode. Since it became operational in June 2009, the AoA has recorded several minor tremor episodes, and the recent episodic tremor and slip (ETS) event in August 2010. During the ETS event, each array was augmented by 10 additional single-channel, vertical-component sensors. We have already started to analyze seismic data for tremor episodes in July 2009, and March 2010. At each array, we apply a beamforming technique to stack the seismic energy at every 0.2 Hz from 2 to 15 Hz. During active tremor, the arrays show stable slowness, and azimuth over time, and up to 15 Hz energy on vertical channels, and 6 Hz on horizontals, with slowness consistent with the P and S waves respectively (Figure 1). Vidale et al. in this meeting provide a detailed description of a weeklong tremor episode in March 2010. The ETS started early second week of August about 60 km south of our arrays, and in a week or so, migrated along-strike to the north passing directly underneath the arrays. Strong tremor is still active about 50 km north of the arrays as we write this abstract. We will imminently analyze this data, and by the time of AGU, have preliminary results to present. Currently, we are developing an algorithm to focus as many arrays as possible to locate the tremor sources. With fine tremor detection capability and good azimuthal coverage, our AoA will better resolve the various confounding features of tremor spatiotemporal distribution (e.g., tremor patches, bands, streaks, rapid tremor reversals, low frequency earthquakes) that have been recently discovered in Cascadia. The AoA is poised to provide

  12. 1-to 10-keV x-ray backlighting of annular wire arrays on the Sandia Z-machine using bent-crystal imaging techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Rambo, Patrick K.; Wenger, David Franklin; Bennett, Guy R.; Sinars, Daniel Brian; Smith, Ian Craig; Porter, John Larry, Jr.; Cuneo, Michael Edward; Rovang, Dean Curtis; Anderson, Jessica E.

    2003-07-01

    Annular wire array implosions on the Sandia Z-machine can produce >200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The x-ray flux and debris in this environment present significant challenges for radiographic diagnostics. X-ray backlighting diagnostics at 1865 and 6181 eV using spherically-bent crystals have been fielded on the Z-machine, each with a {approx}0.6 eVspectral bandpass, 10 {micro}m spatial resolution, and a 4 mm by 20mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser({lambda} = 527 nm), is used to produce 0.1-1 J x-ray sources for radiography. The design, calibration, and performance of these diagnostics is presented.

  13. 1- to 10-keV x-ray backlighting of annular wire arrays on the Sandia Z-machine using bent-crystal imaging techniques

    International Nuclear Information System (INIS)

    Annular wire array implosions on the Sandia Z-machine can produce >200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The x-ray flux and debris in this environment present significant challenges for radiographic diagnostics. X-ray backlighting diagnostics at 1865 and 6181 eV using spherically-bent crystals have been fielded on the Z-machine, each with a ∼0.6 eVspectral bandpass, 10 (micro)m spatial resolution, and a 4 mm by 20mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser(λ = 527 nm), is used to produce 0.1-1 J x-ray sources for radiography. The design, calibration, and performance of these diagnostics is presented.

  14. Passive microfluidic array card and reader

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, Lawrence Christopher (Modesto, CA); Coleman, Matthew A. (Oakland, CA)

    2011-08-09

    A microfluidic array card and reader system for analyzing a sample. The microfluidic array card includes a sample loading section for loading the sample onto the microfluidic array card, a multiplicity of array windows, and a transport section or sections for transporting the sample from the sample loading section to the array windows. The microfluidic array card reader includes a housing, a receiving section for receiving the microfluidic array card, a viewing section, and a light source that directs light to the array window of the microfluidic array card and to the viewing section.

  15. Chunking of Large Multidimensional Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rotem, Doron; Otoo, Ekow J.; Seshadri, Sridhar

    2007-02-28

    Data intensive scientific computations as well on-lineanalytical processing applications as are done on very large datasetsthat are modeled as k-dimensional arrays. The storage organization ofsuch arrays on disks is done by partitioning the large global array intofixed size hyper-rectangular sub-arrays called chunks or tiles that formthe units of data transfer between disk and memory. Typical queriesinvolve the retrieval of sub-arrays in a manner that accesses all chunksthat overlap the query results. An important metric of the storageefficiency is the expected number of chunks retrieved over all suchqueries. The question that immediately arises is "what shapes of arraychunks give the minimum expected number of chunks over a query workload?"In this paper we develop two probabilistic mathematical models of theproblem and provide exact solutions using steepest descent and geometricprogramming methods. Experimental results, using synthetic workloads onreal life data sets, show that our chunking is much more efficient thanthe existing approximate solutions.

  16. On GID—Testable Two—Dimensional Iterative Arrays

    Institute of Scientific and Technical Information of China (English)

    黄维康; F.Lombard

    1994-01-01

    A new approach is presented for easily testable two-dimensional iterative arrays.It is an improvement of GI-testability (Group Identical testability)and is referred to as GID-testability (Group Identical and Different testability).In a GID-testable two-dimensional array,the primary x and y outputs are organized into groups and every group has more than one output.This is similar to the GI-testable arrays.However,GID-testability not only ensures that identical test responses can be obtained from every output in the same group when an array is fault free,but also ensures that at least one output has different test responses (from the other outputs in a group)when a cell in the array is faulty.Therefore,all faults can be detected under the assumption of a single faulty cell model.It is proved that an arbitrary two-dimensional iterative array is GID-testable if seven x-states and seven y-states are added to the original flow table of the basic cell of the array.GID-testability simplifies the response verification of built-in-self-testing in a way similar to PI-and GI-testability[6-9].Therefore,it is suitable for BIST design.

  17. SAQC: SNP Array Quality Control

    Directory of Open Access Journals (Sweden)

    Li Ling-Hui

    2011-04-01

    Full Text Available Abstract Background Genome-wide single-nucleotide polymorphism (SNP arrays containing hundreds of thousands of SNPs from the human genome have proven useful for studying important human genome questions. Data quality of SNP arrays plays a key role in the accuracy and precision of downstream data analyses. However, good indices for assessing data quality of SNP arrays have not yet been developed. Results We developed new quality indices to measure the quality of SNP arrays and/or DNA samples and investigated their statistical properties. The indices quantify a departure of estimated individual-level allele frequencies (AFs from expected frequencies via standardized distances. The proposed quality indices followed lognormal distributions in several large genomic studies that we empirically evaluated. AF reference data and quality index reference data for different SNP array platforms were established based on samples from various reference populations. Furthermore, a confidence interval method based on the underlying empirical distributions of quality indices was developed to identify poor-quality SNP arrays and/or DNA samples. Analyses of authentic biological data and simulated data show that this new method is sensitive and specific for the detection of poor-quality SNP arrays and/or DNA samples. Conclusions This study introduces new quality indices, establishes references for AFs and quality indices, and develops a detection method for poor-quality SNP arrays and/or DNA samples. We have developed a new computer program that utilizes these methods called SNP Array Quality Control (SAQC. SAQC software is written in R and R-GUI and was developed as a user-friendly tool for the visualization and evaluation of data quality of genome-wide SNP arrays. The program is available online (http://www.stat.sinica.edu.tw/hsinchou/genetics/quality/SAQC.htm.

  18. The Long Wavelength Array

    Science.gov (United States)

    Taylor, G. B.

    2006-08-01

    The Long Wavelength Array (LWA) will be a new, open, user-oriented astronomical instrument operating in the poorly explored window from 20-80 MHz at arcsecond level resolution and mJy level sensitivity. Key science drivers include (1) acceleration, propagation, and turbulence in the ISM, including the space-distribution and spectrum of Galactic cosmic rays, supernova remnants, and pulsars; (2) the high redshift universe, including the most distant radio galaxies and clusters - tools for understanding the earliest black holes and the cosmological evolution of Dark Matter and Dark Energy; (3) planetary, solar, and space science, including space weather prediction and extra-solar planet searches; and (4) the radio transient universe: including the known (e.g., SNe, GRBs) and the unknown. Because the LWA will explore one of the last and least investigated regions of the spectrum, the potential for new discoveries, including new classes of physical phenomena, is high, and there is a strong synergy with exciting new X-ray and Gamma-ray measurements, e.g. for cosmic ray acceleration, transients, and galaxy clusters. Operated by the University of New Mexico on behalf of the South West Consortium (SWC) the LWA will also provide a unique training ground for the next generation of radio astronomers. Students may also put skills learned on the LWA to work in computer science, electrical engineering, and the communications industry, among others. The development of the LWA will follow a phased build, which benefits from lessons learned at each phase. Four university-based Scientific Testing and Evaluation (ST&E) teams with different areas of concentration (1. High resolution imaging and particle acceleration; 2. Wide field imaging and large scale structures; 3. Ionosphere, and 4. RFI suppression and transient detection) will provide the feedback needed to assure that science objectives are met as the build develops. Currently in its first year of construction funding, the LWA

  19. The optimal configuration of photovoltaic module arrays based on adaptive switching controls

    International Nuclear Information System (INIS)

    Highlights: • We propose a strategy for determining the optimal configuration of a PV array. • The proposed strategy was based on particle swarm optimization (PSO) method. • It can identify the optimal module array connection scheme in the event of shading. • It can also find the optimal connection of a PV array even in module malfunctions. - Abstract: This study proposes a strategy for determining the optimal configuration of photovoltaic (PV) module arrays in shading or malfunction conditions. This strategy was based on particle swarm optimization (PSO). If shading or malfunctions of the photovoltaic module array occur, the module array immediately undergoes adaptive reconfiguration to increase the power output of the PV power generation system. First, the maximal power generated at various irradiation levels and temperatures was recorded during normal array operation. Subsequently, the irradiation level and module temperature, regardless of operating conditions, were used to recall the maximal power previously recorded. This previous maximum was compared with the maximal power value obtained using the maximum power point tracker to assess whether the PV module array was experiencing shading or malfunctions. After determining that the array was experiencing shading or malfunctions, PSO was used to identify the optimal module array connection scheme in abnormal conditions, and connection switches were used to implement optimal array reconfiguration. Finally, experiments were conducted to assess the strategy for identifying the optimal reconfiguration of a PV module array in the event of shading or malfunctions

  20. Development of a colorimetric sensor array for squid spoilage assessment.

    Science.gov (United States)

    Zaragozá, Patricia; Fuentes, Ana; Ruiz-Rico, María; Vivancos, José-Luis; Fernández-Segovia, Isabel; Ros-Lis, José V; Barat, José M; Martínez-Máñez, Ramón

    2015-05-15

    The aim of this work was to develop and evaluate a rapid, easy-to-use optoelectronic system for the shelf-life assessment of squid in cold storage. For this purpose, an optoelectronic nose was designed, which consisted of an array containing six sensing materials prepared by combining different dyes and two inorganic supports (aluminium oxide and silica gel). Samples were packaged with the colorimetric array and kept in cold storage for 12 days. Squid spoilage was monitored simultaneously by the colorimetric array and by the physico-chemical and microbial analyses during storage. Samples exceeded the acceptability limits for microbial counts on the third day. PCA analysis carried out with CIELab showed that the colorimetric array was able to discriminate between fresh squid fit for consumption and spoiled squid. The statistical models obtained by PLS, with the optoelectronic nose, successfully predicted CO2 and O2 content in the headspace as well as microbial growth. PMID:25577086

  1. Fabrication and Wettability of ZnO Nanorod Array

    Institute of Scientific and Technical Information of China (English)

    Meng Sun; Yi Du; Weichang Hao; Huaizhe Xu; Youxing Yu; Tianmin Wang

    2009-01-01

    ZnO nanorod arrays were prepared in an open system by using a simple aqueous solution method. Spindle-like, wimble-like, tower-like and hexagonal rod-like ZnO rods were obtained under different conditions. ZnO nanorod arrays with different morphology and size were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and contact angle measurement (CAM). The size of ordered zinc oxide rods can be controlled by temperature of water bath, because this temperature can influences growing speeds in different crystal directions. Some additives, such as urea and thiourea, were introduced into reaction solution to improve quality of arrays. Surface character of ZnO nanorod arrays can be changed from hydrophilic to hydrophobic, which was proved to be dependence on size of air grooves on surface.

  2. Quantifier-Free Interpolation of a Theory of Arrays

    CERN Document Server

    Bruttomesso, Roberto; Ranise, Silvio

    2012-01-01

    The use of interpolants in model checking is becoming an enabling technology to allow fast and robust verification of hardware and software. The application of encodings based on the theory of arrays, however, is limited by the impossibility of deriving quantifier- free interpolants in general. In this paper, we show that it is possible to obtain quantifier-free interpolants for a Skolemized version of the extensional theory of arrays. We prove this in two ways: (1) non-constructively, by using the model theoretic notion of amalgamation, which is known to be equivalent to admit quantifier-free interpolation for universal theories; and (2) constructively, by designing an interpolating procedure, based on solving equations between array updates. (Interestingly, rewriting techniques are used in the key steps of the solver and its proof of correctness.) To the best of our knowledge, this is the first successful attempt of computing quantifier- free interpolants for a variant of the theory of arrays with extension...

  3. Packaging of hard solder 500W QCW diode laser array

    Science.gov (United States)

    Li, Xiaoning; Wang, Jingwei; Hou, Dong; Nie, Zhiqiang; Liu, Xingsheng

    2016-03-01

    The package structure critically influences the major characteristics of diode laser, such as thermal behavior, output power, wavelength and smile effect. In this work, a novel micro channel cooler (MCC) for stack array laser with good heat dissipation capability and high reliability is presented. Numerical simulations of thermal management with different MCC structure are conducted and analyzed. Based on this new MCC packaging structure, a series of QCW 500W high power laser arrays with hard solder packaging technology has been fabricated. The performances of the laser arrays are characterized. A narrow spectrum of 3.12 nm and an excellent smile value are obtained. The lifetime of the laser array is more than 1.38×109 shots and still ongoing.

  4. Preliminary experimental study of a carbon fiber array cathode

    Science.gov (United States)

    Li, An-kun; Fan, Yu-wei

    2016-08-01

    The preliminary experimental results of a carbon fiber array cathode for the magnetically insulated transmission line oscillator (MILO) operations are reported. When the diode voltage and diode current were 480 kV and 44 kA, respectively, high-power microwaves with a peak power of about 3 GW and a pulse duration of about 60 ns were obtained in a MILO device with the carbon fiber array cathode. The preliminary experimental results show that the shot-to-shot reproducibility of the diode current and the microwave power is stable until 700 shots. No obvious damage or deterioration can be observed in the carbon fiber surface morphology after 700 shots. Moreover, the cathode performance has no observable deterioration after 700 shots. In conclusion, the maintain-free lifetime of the carbon fiber array cathode is more than 700 shots. In this way, this carbon fiber array cathode offers a potential replacement for the existing velvet cathode.

  5. Integrated Seismic Event Detection and Location by Advanced Array Processing

    Energy Technology Data Exchange (ETDEWEB)

    Kvaerna, T; Gibbons, S J; Ringdal, F; Harris, D B

    2007-02-09

    The principal objective of this two-year study is to develop and test a new advanced, automatic approach to seismic detection/location using array processing. We address a strategy to obtain significantly improved precision in the location of low-magnitude events compared with current fully-automatic approaches, combined with a low false alarm rate. We have developed and evaluated a prototype automatic system which uses as a basis regional array processing with fixed, carefully calibrated, site-specific parameters in conjuction with improved automatic phase onset time estimation. We have in parallel developed tools for Matched Field Processing for optimized detection and source-region identification of seismic signals. This narrow-band procedure aims to mitigate some of the causes of difficulty encountered using the standard array processing system, specifically complicated source-time histories of seismic events and shortcomings in the plane-wave approximation for seismic phase arrivals at regional arrays.

  6. The Cherenkov Telescope Array

    CERN Document Server

    Bigongiari, Ciro

    2016-01-01

    The Cherenkov Telescope Array (CTA) is planned to be the next generation ground based observatory for very high energy (VHE) gamma-ray astronomy. Gamma-rays provide a powerful insight into the non-thermal universe and hopefully a unique probe for new physics. Imaging Cherenkov telescopes have already discovered more than 170 VHE gamma-ray emitters providing plentiful of valuable data and clearly demonstrating the power of this technique. In spite of the impressive results there are indications that the known sources represent only the tip of the iceberg. A major step in sensitivity is needed to increase the number of detected sources, observe short time-scale variability and improve morphological studies of extended sources. An extended energy coverage is advisable to observe far-away extragalactic objects and improve spectral analysis. CTA aims to increase the sensitivity by an order of magnitude compared to current facilities, to extend the accessible gamma-ray energies from a few tens of GeV to a hundred o...

  7. TRANSFORMATION ALGORITHM FOR IMAGES OBTAINED BY OMNIDIRECTIONAL CAMERAS

    Directory of Open Access Journals (Sweden)

    V. P. Lazarenko

    2015-01-01

    Full Text Available Omnidirectional optoelectronic systems find their application in areas where a wide viewing angle is critical. However, omnidirectional optoelectronic systems have a large distortion that makes their application more difficult. The paper compares the projection functions of traditional perspective lenses and omnidirectional wide angle fish-eye lenses with a viewing angle not less than 180°. This comparison proves that distortion models of omnidirectional cameras cannot be described as a deviation from the classic model of pinhole camera. To solve this problem, an algorithm for transforming omnidirectional images has been developed. The paper provides a brief comparison of the four calibration methods available in open source toolkits for omnidirectional optoelectronic systems. Geometrical projection model is given used for calibration of omnidirectional optical system. The algorithm consists of three basic steps. At the first step, we calculate he field of view of a virtual pinhole PTZ camera. This field of view is characterized by an array of 3D points in the object space. At the second step the array of corresponding pixels for these three-dimensional points is calculated. Then we make a calculation of the projection function that expresses the relation between a given 3D point in the object space and a corresponding pixel point. In this paper we use calibration procedure providing the projection function for calibrated instance of the camera. At the last step final image is formed pixel-by-pixel from the original omnidirectional image using calculated array of 3D points and projection function. The developed algorithm gives the possibility for obtaining an image for a part of the field of view of an omnidirectional optoelectronic system with the corrected distortion from the original omnidirectional image. The algorithm is designed for operation with the omnidirectional optoelectronic systems with both catadioptric and fish-eye lenses

  8. Imaging Properties of Planar Microlens Arrays

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The planar microlens arrays is a two-dimensional array of optical component which is fabricated monolithically available. Imaging properties of planar microlens arrays are described, which provide both image multiplexer and erect, unit magnification images.

  9. Volumetric imaging with an amplitude-steered array.

    Science.gov (United States)

    Frazier, Catherine H; Hughes, W Jack; O'Brien, William D

    2002-12-01

    Volumetric acoustic imaging is desirable for the visualization of underwater objects and structures; however, the implementation of a volumetric imaging system is difficult due to the high channel count of a fully populated two-dimensional array. Recently, a linear amplitude-steered array with a reduced electronics requirement was presented, which is capable of collecting a two-dimensional set of data with a single transmit pulse. In this study, we demonstrate the use of the linear amplitude-steered array and associated image formation algorithms for collecting and displaying volumetric data; that is, proof of principle of the amplitude-steering concept and the associated image formation algorithms is demonstrated. Range and vertical position are obtained by taking advantage of the frequency separation of a vertical linear amplitude-steered array. The third dimension of data is obtained by rotating the array such that the mainlobe is mechanically steered in azimuth. Data are collected in a water tank at the Pennsylvania State University Applied Research Laboratory for two targets: a ladder and three pipes. These data are the first experimental data collected with an amplitude-steered array for the purposes of imaging. The array is 10 cm in diameter and is operated in the frequency range of 80 to 304 kHz. Although the array is small for high-resolution imaging at these frequencies, the rungs of the ladder are recognizable in the images. The three pipes are difficult to discern in two of the projection images; however, the pipes separated in range are clear in the image showing vertical position versus range. The imaging concept is demonstrated on measured data, and the simulations agree well with the experimental results. PMID:12508995

  10. Airborne ultrasonic phased arrays using ferroelectrets: a new fabrication approach.

    Science.gov (United States)

    Ealo, Joao L; Camacho, Jorge J; Fritsch, Carlos

    2009-04-01

    In this work, a novel procedure that considerably simplifies the fabrication process of ferroelectret-based multielement array transducers is proposed and evaluated. Also, the potential of ferroelectrets being used as active material for air-coupled ultrasonic transducer design is demonstrated. The new construction method of multi-element transducers introduces 2 distinctive improvements. First, active ferroelectret material is not discretized into elements, and second, the need of structuring upper and/or lower electrodes in advance of the permanent polarization of the film is removed. The aperture discretization and the mechanical connection are achieved in one step using a through-thickness conductive tape. To validate the procedure, 2 linear array prototypes of 32 elements, with a pitch of 3.43 mm and a wide usable frequency range from 30 to 300 kHz, were built and evaluated using a commercial phased-array system. A low crosstalk among elements, below -30 dB, was measured by interferometry. Likewise, a homogeneous response of the array elements, with a maximum deviation of +/-1.8 dB, was obtained. Acoustic beam steering measurements were accomplished at different deflection angles using a calibrated microphone. The ultrasonic beam parameters, namely, lateral resolution, side lobe level, grating lobes, and focus depth, were congruent with theory. Acoustic images of a single reflector were obtained using one of the array elements as the receiver. Resulting images are also in accordance with numerical simulation, demonstrating the feasibility of using these arrays in pulse-echo mode. The proposed procedure simplifies the manufacturing of multidimensional arrays with arbitrary shape elements and not uniformly distributed. Furthermore, this concept can be extended to nonflat arrays as long as the transducer substrate conforms to a developable surface. PMID:19406714

  11. Proportional microvolume capacitive liquid level sensor array.

    Science.gov (United States)

    Seliskar, D; Waterbury, R; Kearney, R

    2005-01-01

    A sensor array has been developed for use with laboratory automation to permit closed-loop control of liquid levels in a multiwell microplate geometry. We extended a simple electrical model for non-contact capacitance-based fluid sensors to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer, employing a liquid-specific calibration, can be used to obtain an output signal that varies linearly with the liquid level. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. A prototype 3×3 sensor array was built and tested using NaCl and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Calibrated output signals were linear with liquid volume for all tested solutions (R2>0.92). Measurement error averaged 1.3 % (2.0 μl) with a standard deviation of 6.0% (9.0 μl). These results demonstrate the feasibility of developing a microvolume sensor array in essentially any M×N microplate geometry. PMID:17281955

  12. Context-free Grammars for Triangular Arrays

    Institute of Scientific and Technical Information of China (English)

    Robert X. J. HAO; Larry X. W. WANG; Harold R. L. YANG

    2015-01-01

    We consider context-free grammars of the form G={f →fb1+b2+1ga1+a2, g→fb1ga1+1}, where ai and bi are integers subject to certain positivity conditions. Such a grammar G gives rise to triangular arrays {T (n, k)}0≤k≤n satisfying a three-term recurrence relation. Many combinatorial sequences can be generated in this way. Let Tn(x)=? nk=0 T (n, k)xk. Based on the diff erential operator with respect to G, we define a sequence of linear operators Pn such that Tn+1(x)=Pn(Tn(x)). Applying the characterization of real stability preserving linear operators on the multivariate polynomials due to Borcea and Bra¨nd´en, we obtain a necessary and suffi cient condition for the operator Pn to be real stability preserving for any n. As a consequence, we are led to a suffi cient condition for the real-rootedness of the polynomials defined by certain triangular arrays, obtained by Wang and Yeh. Moreover, as special cases we obtain grammars that lead to identities involving the Whitney numbers and the Bessel numbers.

  13. Dynamics of large femtosecond filament arrays: possibilities, limitations, and trade-offs

    CERN Document Server

    Walasik, Wiktor

    2015-01-01

    Stable propagation of large, multifilament arrays over long distances in air paves new ways for microwave-radiation manipulation. Although, the dynamics of a single or a few filaments was discussed in some of the previous studies, we show that the stability of large plasma filament arrays is significantly more complicated and is constrained by several trade-offs. Here, we analyze the stability properties of rectangular arrays as a function of four parameters: relative phase of the generating beams, number of filaments, separation between them, and initial power. We find that arrays with alternating phase of filaments are more stable than similar arrays with all beams in phase. Additionally, we show that increasing the size of an array increases its stability, and that a proper choice of the beam separation and the initial power has to be made in order to obtain a dense and regular array of filaments.

  14. Tests of operating conditions for metrological application of HTS Josephson arrays

    International Nuclear Information System (INIS)

    We report on an experimental study of metrological properties of High Temperature Superconductor arrays, made of shunted bicrystal YBCO Josephson junctions, to assess their accuracy. A detailed analysis of measurement errors is presented, mainly based on a direct comparison of an HTS array against a low temperature array. Owing to the high sensitivity of the comparison, we were able to measure the changes in the HTS array voltage on a step at nanovolt level. A precise estimate of the dependence of the HTS array step width on operating conditions was obtained. Differences were observed with respect to the results provided by the usual, low sensitivity, techniques, confirming that the method we adopted is necessary in the study of HTS arrays for metrology. The high sensitivity analysis was applied in the derivation of the temperature dependence of the critical current as well, providing some insights on the behaviour of the HTS array

  15. CLAES focal plane array. [Cryogenic Limb Array Etalon Spectrometer

    Science.gov (United States)

    Roche, A. E.; Sterritt, L. W.; Kumer, J. B.; Callary, P. C.; Nielsen, R. L.

    1989-01-01

    The Cryogenic Limb Array Etalon Spectrometer for the NASA Upper Atmospheric Research Satellite uses solid-state focal plane arrays to detect emission from the earth's atmosphere over the IR wavelength range 3.5 to 13 microns. This paper discusses the design of the focal plane detector assembly and compares calculated performance with measurements. Measurements were made of focal plane noise and responsivity as functions of frequency (2 to 500 Hz) and temperature (12 to 19 K), pixel-to-pixel and across-array crosstalk, and linearity over a dynamic range of 100,000. The measurements demonstrate that the arrays satisfy the science requirements, and that, in general, there is reasonable agreement between the measurements and the analytical model.

  16. Analysis of shock implosion

    Energy Technology Data Exchange (ETDEWEB)

    Mishkin, E.A.; Alejaldre, C. (Polytechnic Inst. of New York, Brooklyn (USA))

    1984-06-01

    An imploding shock wave, coming from infinity, moves through an ideal gas with the adiabatic constant ..gamma... To define a single-valued self-similar coefficient over the whole classical interval 1<..gamma..

  17. Fundamentals of ultrasonic phased arrays

    CERN Document Server

    Schmerr, Lester W

    2014-01-01

    This book describes in detail the physical and mathematical foundations of ultrasonic phased array measurements.?The book uses linear systems theory to develop a comprehensive model of the signals and images that can be formed with phased arrays. Engineers working in the field of ultrasonic nondestructive evaluation (NDE) will find in this approach a wealth of information on how to design, optimize and interpret ultrasonic inspections with phased arrays. The fundamentals and models described in the book will also be of significant interest to other fields, including the medical ultrasound and

  18. Antenna arrays a computational approach

    CERN Document Server

    Haupt, Randy L

    2010-01-01

    This book covers a wide range of antenna array topics that are becoming increasingly important in wireless applications, particularly in design and computer modeling. Signal processing and numerical modeling algorithms are explored, and MATLAB computer codes are provided for many of the design examples. Pictures of antenna arrays and components provided by industry and government sources are presented with explanations of how they work. Antenna Arrays is a valuable reference for practicing engineers and scientists in wireless communications, radar, and remote sensing, and an excellent textbook for advanced antenna courses.

  19. A gamma-ray detector array for joint spectroscopy experiments at the JAERI tandem-booster facility

    CERN Document Server

    Furuno, K; Komatsubara, T; Furutaka, K; Hayakawa, T; Kidera, M; Hatsukawa, Y; Matsuda, M; Mitarai, S; Shizuma, T; Saitoh, T R; Hashimoto, N; Kusakari, H; Sugawara, M; Morikawa, T

    1999-01-01

    A compact array for gamma-ray spectroscopy developed for the joint experiment at the Japan Atomic Energy Research Institute is described. It consists of an array of 11 Compton suppressed Ge detectors, a 4 pi silicon detector array for charged particle measurements, a position-sensitive silicon detector for experiments on Coulomb excitation and a conversion-electron spectrometer. The details of the detectors and new experimental results obtained with the compact array are also described.

  20. Gold planar wire array radiation sources at university scale generators and their applications

    International Nuclear Information System (INIS)

    Various configurations of planar wires arrays (PWA) made from wires in a broad range of atomic numbers up to 74 (W) have been extensively tested on Zebra generator at the University of Nevada, Reno. In this work, we present the results of our experiments with PWA made of the wires with an even higher atomic number, specifically 79 (Au). Two different configurations (single and double PWAs) are considered. The diagnostic set included: x-ray detectors, laser shadowgraphy, time-gated and time-integrated x-ray pinhole cameras, time-integrated spatially resolved and time-gated spatially integrated x-ray spectrometers, and a bolometer. The total x-ray yield was measured along and perpendicular to the load plane and reached the highest value measured on Zebra so far for the single PWA (perpendicular to the plane, 32 kJ). Theoretical tools included non-LTE kinetic and wire ablation dynamic models. The full set of data using aforementioned diagnostics is analyzed and specific implosion and radiative characteristics of Au PWAs. The application of gold PWAs in compact hohlraum configurations on Zebra is highlighted. VisRad (Prism Computational Sciences), a 3-D view factor code, is used to simulate the multi-dimensional radiation environment with a special emphasis on radiation temperature calculations and uniformity at the re-emission target surface. (author)

  1. Silicon Heat Pipe Array

    Science.gov (United States)

    Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

    2013-01-01

    Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better

  2. Numerical and experimental investigations on the interaction of light wire-array Z-pinches with embedded heavy foam converters

    International Nuclear Information System (INIS)

    The interaction of a light tungsten wire-array Z-pinch with an embedded heavy foam converter, whose mass ratio is typically less than 0.16, is numerically analyzed and experimentally investigated on the 1.3 MA “QiangGuang I” facility. Computational results show that this implosion process can be divided into three stages: acceleration of the tungsten wire-array plasma, collision, and stagnation. The tungsten plasma is accelerated to a high speed by the J × B force and interacts weakly with the foam plasma in the first stage. Strong energy conversions take place in the second collision stage. When the high speed tungsten plasma impacts on the foam converter, the plasma is thermalized and a radial radiation peak is produced. Meanwhile, a shock wave is generated due to the collision. After the shock rebounds from the axis and meets the W/Foam boundary, the plasma stagnates and the second radial radiation peak appears. The collision and stagnation processes were observed and the two-peak radial radiation pulse was produced in experiments. Increasing the wire-array radius from 4 mm to 6 mm, the kinetic energy of the tungsten plasma is increased, causing a stronger thermalization and generating a higher first radiation peak. Experimental results also showed a higher ratio of the first peak to the second peak in the case of larger wire-array radius. If we add a thin CH film cover onto the surface of the embedded foam converter, the first radiation peak will be hardly changed, because the acceleration of the tungsten plasma is not evidently affected by the film cover. However, the second radiation peak decreases remarkably due to the large load mass and the corresponding weak compression

  3. Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments

    Science.gov (United States)

    Ruby, J. J.; Pak, A.; Field, J. E.; Ma, T.; Spears, B. K.; Benedetti, L. R.; Bradley, D. K.; Berzak Hopkins, L. F.; Casey, D. T.; Döppner, T.; Eder, D.; Fittinghoff, D.; Grim, G.; Hatarik, R.; Hinkel, D. E.; Izumi, N.; Kilkenny, J. D.; Khan, S. F.; Knauer, J. P.; Kritcher, A. L.; Merrill, F. E.; Moody, J. D.; Nagel, S. R.; Park, H.-S.; Salmonson, J. D.; Sayre, D. B.; Callahan, D. A.; Hsing, W. W.; Hurricane, O. A.; Patel, P. K.; Edwards, M. J.

    2016-07-01

    A technique for measuring residual motion during the stagnation phase of an indirectly driven inertial confinement experiment has been implemented. This method infers a velocity from spatially and temporally resolved images of the X-ray emission from two orthogonal lines of sight. This work investigates the accuracy of recovering spatially resolved velocities from the X-ray emission data. A detailed analytical and numerical modeling of the X-ray emission measurement shows that the accuracy of this method increases as the displacement that results from a residual velocity increase. For the typical experimental configuration, signal-to-noise ratios, and duration of X-ray emission, it is estimated that the fractional error in the inferred velocity rises above 50% as the velocity of emission falls below 24 μm/ns. By inputting measured parameters into this model, error estimates of the residual velocity as inferred from the X-ray emission measurements are now able to be generated for experimental data. Details of this analysis are presented for an implosion experiment conducted with an unintentional radiation flux asymmetry. The analysis shows a bright localized region of emission that moves through the larger emitting volume at a relatively higher velocity towards the location of the imposed flux deficit. This technique allows for the possibility of spatially resolving velocity flows within the so-called central hot spot of an implosion. This information would help to refine our interpretation of the thermal temperature inferred from the neutron time of flight detectors and the effect of localized hydrodynamic instabilities during the stagnation phase. Across several experiments, along a single line of sight, the average difference in magnitude and direction of the measured residual velocity as inferred from the X-ray and neutron time of flight detectors was found to be ˜13 μm/ns and ˜14°, respectively.

  4. Hydrodynamic instability growth of three-dimensional, "native-roughness" modulations in x-ray driven, spherical implosions at the National Ignition Facility

    Science.gov (United States)

    Smalyuk, V. A.; Weber, S. V.; Casey, D. T.; Clark, D. S.; Field, J. E.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Hoover, D. E.; Landen, O. L.; Nikroo, A.; Robey, H. F.; Weber, C. R.

    2015-07-01

    Hydrodynamic instability growth experiments with three-dimensional (3-D) surface-roughness modulations were performed on plastic (CH) shell spherical implosions at the National Ignition Facility (NIF) [E. M. Campbell, R. Cauble, and B. A. Remington, AIP Conf. Proc. 429, 3 (1998)]. The initial capsule outer-surface roughness was similar to the standard specifications ("native roughness") used in a majority of implosions on NIF. The experiments included instability growth measurements of the perturbations seeded by the thin membranes (or tents) used to hold the capsules inside the hohlraums. In addition, initial modulations included two divots used as spatial fiducials to determine the convergence in the experiments and to check the accuracy of 3D simulations in calculating growth of known initial perturbations. The instability growth measurements were performed using x-ray, through-foil radiography of one side of the imploding shell, based on time-resolved pinhole imaging. Averaging over 30 similar images significantly increases the signal-to-noise ratio, making possible a comparison with 3-D simulations. At a convergence ratio of ˜3, the measured tent and divot modulations were close to those predicted by 3-D simulations (within ˜15%-20%), while measured 3-D, broadband modulations were ˜3-4 times larger than those simulated based on the growth of the known imposed initial surface modulations. In addition, some of the measured 3-D features in x-ray radiographs did not resemble those characterized on the outer capsule surface before the experiments. One of the hypotheses to explain the results is based on the increased instability amplitudes due to modulations of the oxygen content in the bulk of the capsule. As the target assembly and handling procedures involve exposure to UV light, this can increase the uptake of the oxygen into the capsule, with irregularities in the oxygen seeding hydrodynamic instabilities. These new experimental results have prompted

  5. Hydrodynamic instability growth of three-dimensional, “native-roughness” modulations in x-ray driven, spherical implosions at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Smalyuk, V. A.; Weber, S. V.; Casey, D. T.; Clark, D. S.; Field, J. E.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Landen, O. L.; Robey, H. F.; Weber, C. R. [Lawrence Livermore National Laboratory, NIF Directorate, Livermore, California 94550 (United States); Hoover, D. E.; Nikroo, A. [General Atomics, San Diego, California 92186 (United States)

    2015-07-15

    Hydrodynamic instability growth experiments with three-dimensional (3-D) surface-roughness modulations were performed on plastic (CH) shell spherical implosions at the National Ignition Facility (NIF) [E. M. Campbell, R. Cauble, and B. A. Remington, AIP Conf. Proc. 429, 3 (1998)]. The initial capsule outer-surface roughness was similar to the standard specifications (“native roughness”) used in a majority of implosions on NIF. The experiments included instability growth measurements of the perturbations seeded by the thin membranes (or tents) used to hold the capsules inside the hohlraums. In addition, initial modulations included two divots used as spatial fiducials to determine the convergence in the experiments and to check the accuracy of 3D simulations in calculating growth of known initial perturbations. The instability growth measurements were performed using x-ray, through-foil radiography of one side of the imploding shell, based on time-resolved pinhole imaging. Averaging over 30 similar images significantly increases the signal-to-noise ratio, making possible a comparison with 3-D simulations. At a convergence ratio of ∼3, the measured tent and divot modulations were close to those predicted by 3-D simulations (within ∼15%–20%), while measured 3-D, broadband modulations were ∼3–4 times larger than those simulated based on the growth of the known imposed initial surface modulations. In addition, some of the measured 3-D features in x-ray radiographs did not resemble those characterized on the outer capsule surface before the experiments. One of the hypotheses to explain the results is based on the increased instability amplitudes due to modulations of the oxygen content in the bulk of the capsule. As the target assembly and handling procedures involve exposure to UV light, this can increase the uptake of the oxygen into the capsule, with irregularities in the oxygen seeding hydrodynamic instabilities. These new experimental results have

  6. Finite Element Analysis Of Thermal Transients In Multi-Stripe Laser Diode Arrays

    Science.gov (United States)

    Lippincott, Wendy L.; Clement, Anne E.

    1989-05-01

    The NASTRAN finite element code was used to simulate the temperature transients in the active area of laser diode arrays caused by driving the array with a pulsed waveform. A ten-stripe multi-quantum-well (MQW) structure was used. The thermal impedance of the array was also determined and compared to experimental values obtained by monitoring the threshold dependance of the device during pulsed and cw operation. The single-stripe diode was also modeled for comparison purposes.

  7. Fundamentals of spherical array processing

    CERN Document Server

    Rafaely, Boaz

    2015-01-01

    This book provides a comprehensive introduction to the theory and practice of spherical microphone arrays. It is written for graduate students, researchers and engineers who work with spherical microphone arrays in a wide range of applications.   The first two chapters provide the reader with the necessary mathematical and physical background, including an introduction to the spherical Fourier transform and the formulation of plane-wave sound fields in the spherical harmonic domain. The third chapter covers the theory of spatial sampling, employed when selecting the positions of microphones to sample sound pressure functions in space. Subsequent chapters present various spherical array configurations, including the popular rigid-sphere-based configuration. Beamforming (spatial filtering) in the spherical harmonics domain, including axis-symmetric beamforming, and the performance measures of directivity index and white noise gain are introduced, and a range of optimal beamformers for spherical arrays, includi...

  8. The Murchison Widefield Array Correlator

    CERN Document Server

    Ord, S M; Emrich, D; Pallot, D; Wayth, R B; Clark, M A; Tremblay, S E; Arcus, W; Barnes, D; Bell, M; Bernardi, G; Bhat, N D R; Bowman, J D; Briggs, F; Bunton, J D; Cappallo, R J; Corey, B E; Deshpande, A A; deSouza, L; Ewell-Wice, A; Feng, L; Goeke, R; Greenhill, L J; Hazelton, B J; Herne, D; Hewitt, J N; Hindson, L; Hurley-Walker, H; Jacobs, D; Johnston-Hollitt, M; Kaplan, D L; Kasper, J C; Kincaid, B B; Koenig, R; Kratzenberg, E; Kudryavtseva, N; Lenc, E; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Offringa, A; Pathikulangara, J; Pindor, B; Prabu, T; Procopio, P; Remillard, R A; Riding, J; Rogers, A E E; Roshi, A; Salah, J E; Sault, R J; Shankar, N Udaya; Srivani, K S; Stevens, J; Subrahmanyan, R; Tingay, S J; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C L; Wyithe, J S B

    2015-01-01

    The Murchison Widefield Array (MWA) is a Square Kilometre Array (SKA) Precursor. The telescope is located at the Murchison Radio--astronomy Observatory (MRO) in Western Australia (WA). The MWA consists of 4096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays (FPGAs), and others by Graphics Processing Units (GPUs) housed in general purpose rack mounted servers. The correlation capability required is approximately 8 TFLOPS (Tera FLoating point Operations Per Second). The MWA has commenced operations and the correlator is generating 8.3 TB/day of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper we outline the correlator design, signal path, and proce...

  9. Light propagation in nanorod arrays

    CERN Document Server

    Rahachou, A I

    2006-01-01

    We study propagation of TM- and TE-polarized light in two-dimensional arrays of silver nanorods of various diameters in a gelatin background. We calculate the transmittance, reflectance and absorption of arranged and disordered nanorod arrays and compare the exact numerical results with the predictions of the Maxwell-Garnett effective-medium theory. We show that interactions between nanorods, multipole contributions and formations of photonic gaps affect strongly the transmittance spectra that cannot be accounted for in terms of the conventional effective-medium theory. We also demonstrate and explain the degradation of the transmittance in arrays with randomly located rods as well as weak influence of their fluctuating diameter. For TM modes we outline the importance of skin-effect, which causes the full reflection of the incoming light. We then illustrate the possibility of using periodic arrays of nanorods as high-quality polarizers.

  10. Integrated Spatial Filter Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA Earth Science Division need for spatial filter arrays for amplitude and wavefront control, Luminit proposes to develop a novel Integrated...

  11. Next Generation Microshutter Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop the next generation MicroShutter Array (MSA) as a multi-object field selector for missions anticipated in the next two decades. For many...

  12. Thermopile Area Array Readout Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA/JPL thermopile detector linear arrays, wire bonded to Black Forest Engineering (BFE) CMOS readout integrated circuits (ROICs), have been utilized in NASA...

  13. Convergence in the r-th Mean and the Marcinkiewicz Type Weak Law of Large Numbers for Weighted Sums of Lq-mixingale Arrays

    Institute of Scientific and Technical Information of China (English)

    Gan Shi-xin

    2003-01-01

    Lr convergence and convergence in probability for weighted sums of Lq-mixingale arrays have been discussed and the Marcinkiewicz type weak law of large numbers for Lq-mixingale arrays has been obtained.

  14. Solar maximum: solar array degradation

    International Nuclear Information System (INIS)

    The 5-year in-orbit power degradation of the silicon solar array aboard the Solar Maximum Satellite was evaluated. This was the first spacecraft to use Teflon R FEP as a coverglass adhesive, thus avoiding the necessity of an ultraviolet filter. The peak power tracking mode of the power regulator unit was employed to ensure consistent maximum power comparisons. Telemetry was normalized to account for the effects of illumination intensity, charged particle irradiation dosage, and solar array temperature. Reference conditions of 1.0 solar constant at air mass zero and 301 K (28 C) were used as a basis for normalization. Beginning-of-life array power was 2230 watts. Currently, the array output is 1830 watts. This corresponds to a 16 percent loss in array performance over 5 years. Comparison of Solar Maximum Telemetry and predicted power levels indicate that array output is 2 percent less than predictions based on an annual 1.0 MeV equivalent election fluence of 2.34 x ten to the 13th power square centimeters space environment

  15. Uniaxially aligned ceramic nanofibers obtained by chemical mechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Tararam, R. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil); Foschini, C.R. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Bauru, Dept. de Eng. Mecanica, Av. Eng. Luiz Edmundo C. Coube 14-01, CEP 17033-360 Bauru, SP (Brazil); Destro, F.B. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Longo, E.; Varela, J.A. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil)

    2014-08-01

    For this study, we investigated a simple method to generate well aligned nanofibers over large areas using an organic polymer stretched over the substrate surface With this method, ZnO and CuO 3D parallel nanowire arrays were successfully prepared by calcinations of the polymer fibers. X-ray diffraction (XRD) analysis revealed that the copper oxide has a monoclinic structure while the zinc oxide has a hexagonal structure. Scanning electron microscopy (SEM) analysis showed ceramic nanofibers with an average diameter of 120 nm which were composed of small nanoparticles which are 10 nm in diameter. The ability to obtain uniaxially aligned nanofibers reveals a range of interesting properties with potential applications for sensors, catalysts and energy technologies.

  16. Investigation of correlation characteristics for random array collaborative beamforming using noise signals

    Science.gov (United States)

    Alexander, David B.; Narayanan, Ram M.; Himed, Braham

    2016-05-01

    The performance of different random array geometries is analyzed and compared. Three phased array geometries are considered: linear arrays with non-uniform randomized spacing between elements, circular arrays with non-uniform element radii, and ad hoc sensor networks with elements located randomly within a circular area. For each of these array geometries, computer simulations modeled the transmission, reflection from an arbitrary target, and reception of signals. The effectiveness of each array's beamforming techniques was measured by taking the peak cross-correlation between the received signal and a time-delayed replica of the original transmitted signal. For each array type, the correlation performance was obtained for transmission and reception of both chirp waveforms and ultra-wideband noise signals. It was found that the non-uniform linear array generally produced the highest correlation between transmitted and reflected signals. The non-uniform circular and ad hoc arrays demonstrated the most consistent performance with respect to noise signal bandwidth. The effect of scan angle was found to have a significant impact on the correlation performance of the linear arrays, where the correlation performance declines as the scan angle moves away from broadside to the array.

  17. Solar Array Verification Analysis Tool (SAVANT) Developed

    Science.gov (United States)

    Bailey, Sheila G.; Long, KIenwyn J.; Curtis, Henry B.; Gardner, Barbara; Davis, Victoria; Messenger, Scott; Walters, Robert

    1999-01-01

    Modeling solar cell performance for a specific radiation environment to obtain the end-of-life photovoltaic array performance has become both increasingly important and, with the rapid advent of new types of cell technology, more difficult. For large constellations of satellites, a few percent difference in the lifetime prediction can have an enormous economic impact. The tool described here automates the assessment of solar array on-orbit end-of-life performance and assists in the development and design of ground test protocols for different solar cell designs. Once established, these protocols can be used to calculate on-orbit end-of-life performance from ground test results. The Solar Array Verification Analysis Tool (SAVANT) utilizes the radiation environment from the Environment Work Bench (EWB) model developed by the NASA Lewis Research Center s Photovoltaic and Space Environmental Effects Branch in conjunction with Maxwell Technologies. It then modifies and combines this information with the displacement damage model proposed by Summers et al. (ref. 1) of the Naval Research Laboratory to determine solar cell performance during the course of a given mission. The resulting predictions can then be compared with flight data. The Environment WorkBench (ref. 2) uses the NASA AE8 (electron) and AP8 (proton) models of the radiation belts to calculate the trapped radiation flux. These fluxes are integrated over the defined spacecraft orbit for the duration of the mission to obtain the total omnidirectional fluence spectra. Components such as the solar cell coverglass, adhesive, and antireflective coatings can slow and attenuate the particle fluence reaching the solar cell. In SAVANT, a continuous slowing down approximation is used to model this effect.

  18. Struetural and Magnetic Properties of Electrodeposited Ni70Fe30 Nanowire Array

    Institute of Scientific and Technical Information of China (English)

    XU Jinxia; WANG Keyu

    2008-01-01

    Ordered Ni70Fe30 nanowire array was fabricated in a porous alumina template by altemating current electrodeDositiOn.The structural and magnetic properties of the as-obtained nanowire array were investigated by SEM,TEM,XRD,EDS and VSM.The results indicate that the as-obtained Ni70Fe30 nanowires exhibit a diameter of about 69.9 nm and aspect ratio of more than 60.Meanwhile,a preferred orientation[110]of bcc lattice was observed.The as-obtained nanowire array has an obvious magnetic anisotropy,of which the easy direction is perpendicular to the surface of the array.Moreover,after annealed,the Ni70Fe30 nanowire array exhibits an enhanced magnetic anisotropy.

  19. Performance analysis of solar cell arrays in concentrating light intensity

    International Nuclear Information System (INIS)

    Performance of concentrating photovoltaic/thermal system is researched by experiment and simulation calculation. The results show that the I-V curve of the GaAs cell array is better than that of crystal silicon solar cell arrays and the exergy produced by 9.51% electrical efficiency of the GaAs solar cell array can reach 68.93% of the photovoltaic/thermal system. So improving the efficiency of solar cell arrays can introduce more exergy and the system value can be upgraded. At the same time, affecting factors of solar cell arrays such as series resistance, temperature and solar irradiance also have been analyzed. The output performance of a solar cell array with lower series resistance is better and the working temperature has a negative impact on the voltage in concentrating light intensity. The output power has a -20 W/V coefficient and so cooling fluid must be used. Both heat energy and electrical power are then obtained with a solar trough concentrating photovoltaic/thermal system. (semiconductor devices)

  20. Fusion Implosion Fluid after Indirectly Driven by Laser Beam Instability%聚变内爆流体受激光间接驱动后的不稳定性表现

    Institute of Scientific and Technical Information of China (English)

    陈红利; 杨永和

    2015-01-01

    Fluid dynamics that occur multilayer target ball each interface instability related to the indirect drive inertial confinement fu-sion ignition success,that burst medium radiation related shooting in fluid mechanics local 3D application program of LARED -S through the analysis of the process.We find the system summary and feedback,and draw a conclusion that the instability of linear and weakly nonlinear results through the presentation of the results obtained,which are consistent with the nonlinear test,analysis of the construction by the corresponding numerical simulation test and the bronze drum aluminum wheel model,obtain the ICf detonation physics significance of observation ignition research significance and draw the conclusion as the nature of fluid,the fusion after the out-break in the in life,the fluid and the corresponding laser have the indirect effect of unstable drive,the emergence of a feedback insta-bility makes the fusion implosion fluid numerical increase and pressure expansion phenomenon.%多层靶球每个界面所发生的流体力学的不稳定关系到激光间接驱动惯性约束聚变的点火成功,通过对过程的分析得出爆多介质辐射相关射流体力学中的局部三维应用 LARED -S 程序。得出系统的总结和反馈,并通过结果得出不稳定性线性和弱非线性结果的表述,进而非线性试验都符合,通过相应的模拟数值试验并铜鼓铝轮模型构建分析,得出 ICf 爆点火研究意义并得出自然界流体的物理学观察意义,其结论为其聚变后内爆发生中,相应的流体和激光产生不稳定的间接影响驱动,出现一种不稳定的反馈使得聚变后内爆流体出现数值增加和压力膨胀现象。

  1. Fabrication of arrayed glassy carbon field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Sohda, Y.; Tanenbaum, D.M.; Turner, S.W.; Craighead, H.G. [School of Engineering and Applied Physics, Cornell University, Ithaca, New York 14853 (United States)

    1997-03-01

    Glassy carbon has desirable properties for electron field emission such as surface inertness, electrical conductivity, and thermal stability. In addition, a uniform thick substrate with a polished surface is easily obtainable. This enables one to apply large scale integrated circuit processing for fabricating arrayed tips. By using oxygen reactive ion etching, cusps over 3.5 {mu}m in height and 2.5 {mu}m in base diameter are fabricated with a tip radius of under 10 nm. The process is assisted by the formation of a layer of etch products which protects the newly forming tip from bending and over etching. The field emission current up to 50 {mu}A from the glassy carbon tips is obtained by applying high voltage to a mesh anode. The current which passed through the mesh anode is collected at another electrode and measured. The Fowler{endash}Nordheim plot suggests the existence of nm scale structure on the tip. This favorable result indicates glassy carbon substrate is a good substrate for field emitter arrays. {copyright} {ital 1997 American Vacuum Society.}

  2. Coherent addition of two dimensional array of fiber lasers

    CERN Document Server

    Fridman, Moti; Davidson, Nir; Friesem, Asher A; Luria, Elena; Krupkin, Vladimir

    2008-01-01

    Configurations for efficient free space coherent addition of four separate fiber lasers arranged in two dimensional array are presented. They include compact and robust interferometric combiners that can be inserted either inside or outside the cavity of the combined lasers system. The results reveal that over 85% combining efficiency can be obtained.

  3. Limited Diffraction Maps for Pulsed Wave Annular Arrays

    DEFF Research Database (Denmark)

    Fox, Paul D.

    2002-01-01

    A procedure is provided for decomposing the linear field of flat pulsed wave annular arrays into an equivalent set of known limited diffraction Bessel beams. Each Bessel beam propagates with known characteristics, enabling good insight into the propagation of annular fields to be obtained...

  4. Vapor Phase Detection Using Chemi-Resistor Sensor Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Nathan S. Lewis

    1999-02-17

    This paper focuses on two main areas: understanding sensor response times so as to obtain improved time response in the field when needed for vapor tracking and classification, and improved theoretical understanding of the sensor response properties that generate the pattern on the array in response to a given analyte.

  5. Method for obtaining solid micro -or nanoparticles

    OpenAIRE

    Ventosa Rull, Nora; Veciana Miró, Jaume; Cano Sarabia, Mary; Sala Vergés, Santiago

    2008-01-01

    [EN] The invention provides a novel method for obtaining solid micro -or nanoparticIes with a homogeneous structure. A method is provided for obtaining solid micro -or nanoparticIes with a homogeneous structure having a particIe size of less than 10 /lm where the processed solid compound has the natural, crystalline, amorphous, polymorphic and other features associated with the starting compound. In accordance with the invention a method which also makes it possible to obtain solid m...

  6. Design of Circularly-Polarised, Crossed Drooping Dipole, Phased Array Antenna Using Genetic Algorithm Optimisation

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal

    2007-01-01

    A printed drooping dipole array is designed and constructed. The design is based on a genetic algorithm optimisation procedure used in conjunction with the software programme AWAS. By optimising the array G/T for specific combinations of scan angles and frequencies an optimum design is obtained...

  7. Planar Circularly Symmetric EBG's to Improve the Isolation of Array Elements

    NARCIS (Netherlands)

    Llombart, N.; Neto, A.; Gerini, G.; Maagt, P. de

    2005-01-01

    A trade off has to be made between bandwidth and isolation of array elements when designing phased arrays. When the isolation is achieved via a PCS-EBG that is aimed at reducing the TM00 mode only, the reduction of bandwidth could be even more important rather than the one obtained when using a more

  8. The interaction field in arrays of ferromagnetic barcode nanowires

    International Nuclear Information System (INIS)

    A theoretical model and an experimental approach to the identification of the interaction field in ferromagnetic barcode nanowires are described and applied to electrodeposited Ni/Au cylindrical barcode arrays. Elementary hysteresis loops of individual magnetic segments in these barcode nanowires are considered as superpositions of fully irreversible and locally reversible magnetization processes, whose distributions of switching fields are experimentally identified by first order reversal curve measurements. Non-interacting major hysteresis loops of the arrays are computed as superpositions of several elementary loops by considering the distributions of switching fields as probability density functions. The interaction field is then computed from the condition that the geometric transformation of the experimental major hysteresis loop into the Preisach operative plane be well approximated by this non-interacting hysteresis loop. Experimental interaction field values are compared with those obtained by numerical micromagnetic computations and a very good agreement is obtained on extended Ni/Au barcode arrays. The simple and accurate phenomenological model for the interaction field in multisegmented ferromagnetic nanowire arrays proposed here provides an insight into the morphology of these magnetic nanomaterials, as quantitative information about individual nano-objects may be extracted from macroscopic measurements of their arrays

  9. The interaction field in arrays of ferromagnetic barcode nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Clime, L [NRC, Industrial Materials Institute, 75 de Mortagne Boulevard, Boucherville, J4B 6Y4 (Canada); Zhao, S Y [NRC, Industrial Materials Institute, 75 de Mortagne Boulevard, Boucherville, J4B 6Y4 (Canada); Chen, P [Research Center for Applied Sciences, Academia Sinica 128 Section 2, Academia Rd, Nankang, Taipei 11529, Taiwan (China); Normandin, F [NRC, Industrial Materials Institute, 75 de Mortagne Boulevard, Boucherville, J4B 6Y4 (Canada); Roberge, H [NRC, Industrial Materials Institute, 75 de Mortagne Boulevard, Boucherville, J4B 6Y4 (Canada); Veres, T [NRC, Industrial Materials Institute, 75 de Mortagne Boulevard, Boucherville, J4B 6Y4 (Canada)

    2007-10-31

    A theoretical model and an experimental approach to the identification of the interaction field in ferromagnetic barcode nanowires are described and applied to electrodeposited Ni/Au cylindrical barcode arrays. Elementary hysteresis loops of individual magnetic segments in these barcode nanowires are considered as superpositions of fully irreversible and locally reversible magnetization processes, whose distributions of switching fields are experimentally identified by first order reversal curve measurements. Non-interacting major hysteresis loops of the arrays are computed as superpositions of several elementary loops by considering the distributions of switching fields as probability density functions. The interaction field is then computed from the condition that the geometric transformation of the experimental major hysteresis loop into the Preisach operative plane be well approximated by this non-interacting hysteresis loop. Experimental interaction field values are compared with those obtained by numerical micromagnetic computations and a very good agreement is obtained on extended Ni/Au barcode arrays. The simple and accurate phenomenological model for the interaction field in multisegmented ferromagnetic nanowire arrays proposed here provides an insight into the morphology of these magnetic nanomaterials, as quantitative information about individual nano-objects may be extracted from macroscopic measurements of their arrays.

  10. Instrumentation for multi-detector arrays

    Indian Academy of Sciences (India)

    R K Bhowmik

    2001-07-01

    The new generation of detector arrays require complex instrumentation and data acquisition system to ensure increased reliability of operation, high degree of integration, software control and faster data handling capability. The main features of some of the existing multi-detector arrays like MSU 4 array, Gammasphere and Eurogam are summarized. The instrumentation for the proposed INGA array in India is discussed.

  11. 40 CFR 35.6305 - Obtaining supplies.

    Science.gov (United States)

    2010-07-01

    ... STATE AND LOCAL ASSISTANCE Cooperative Agreements and Superfund State Contracts for Superfund Response Actions Personal Property Requirements Under A Cooperative Agreement § 35.6305 Obtaining supplies....

  12. 40 CFR 35.6310 - Obtaining equipment.

    Science.gov (United States)

    2010-07-01

    ... STATE AND LOCAL ASSISTANCE Cooperative Agreements and Superfund State Contracts for Superfund Response Actions Personal Property Requirements Under A Cooperative Agreement § 35.6310 Obtaining equipment....

  13. Semiconductor arrays with multiplexer readout for gamma-ray imaging: results for a 48 × 48 Ge array

    Science.gov (United States)

    Barber, H. B.; Augustine, F. L.; Barrett, H. H.; Dereniak, E. L.; Matherson, K. L.; Meyers, T. J.; Perry, D. L.; Venzon, J. E.; Woolfenden, J. M.; Young, E. T.

    1994-12-01

    We are developing a new kind of gamma-ray imaging device that has sub-millimeter spatial resolution and excellent energy resolution. The device is composed of a slab of semiconductor detector partitioned into an array of detector cells by photolithography and connected to a monolithic circuit chip called a multiplexer (MUX) for readout. Our application is for an ultra-high-resolution SPECT system for functional brain imaging using an injected radiotracer. We report here on results obtained with a Hughes 48 × 48 Ge PIN-photodiode array with MUX readout, originally developed as an infrared focal-plane-array imaging sensor. The device functions as an array of individual gamma-ray detectors with minimal interpixel crosstalk. Linearity of energy response is excellent up to at least 140 keV. The array exhibits excellent energy resolution, ˜ 2 keV at ≤ 140 keV or 1.5% FWHM at 140 keV. The energy resolution is dominated by MUX readout noise and so should improve with MUX optimization for gamma-ray detection. The spatial resolution of the 48 × 48 Ge array is essentially the same as the pixel spacing, 125 μm. The quantum efficiency is limited by the thin Ge detector (0.25 mm), but this approach is readily applicable to thicker Ge detectors and room-temperature semiconductor detectors such as CdTe, HgI 2 and CdZnTe.

  14. Alternative Optimizations of X-ray TES Arrays: Soft X-rays, High Count Rates, and Mixed-Pixel Arrays

    Science.gov (United States)

    Kilbourne, C. A.; Bandler, S. R.; Brown, A.-D.; Chervenak, J. A.; Figueroa-Feliciano, E.; Finkbeiner, F. M.; Iyomoto, N.; Kelley, R. L.; Porter, F. S.; Smith, S. J.

    2007-01-01

    We are developing arrays of superconducting transition-edge sensors (TES) for imaging spectroscopy telescopes such as the XMS on Constellation-X. While our primary focus has been on arrays that meet the XMS requirements (of which, foremost, is an energy resolution of 2.5 eV at 6 keV and a bandpass from approx. 0.3 keV to 12 keV), we have also investigated other optimizations that might be used to extend the XMS capabilities. In one of these optimizations, improved resolution below 1 keV is achieved by reducing the heat capacity. Such pixels can be based on our XMS-style TES's with the separate absorbers omitted. These pixels can added to an array with broadband response either as a separate array or interspersed, depending on other factors that include telescope design and science requirements. In one version of this approach, we have designed and fabricated a composite array of low-energy and broad-band pixels to provide high spectral resolving power over a broader energy bandpass than could be obtained with a single TES design. The array consists of alternating pixels with and without overhanging absorbers. To explore optimizations for higher count rates, we are also optimizing the design and operating temperature of pixels that are coupled to a solid substrate. We will present the performance of these variations and discuss other optimizations that could be used to enhance the XMS or enable other astrophysics experiments.

  15. Maxima of Dirichlet and triangular arrays of gamma variables

    OpenAIRE

    Bose, Arup; Dasgupta, Amites; Maulik, Krishanu

    2008-01-01

    Consider a rowwise independent triangular array of gamma random variables with varying parameters. Under several different conditions on the shape parameter, we show that the sequence of row-maximums converges weakly after linear or power transformation. Depending on the parameter combinations, we obtain both Gumbel and non-Gumbel limits. The weak limits for maximum of the coordinates of certain Dirichlet vectors of increasing dimension are also obtained using the gamma representation.

  16. Solid-state array cameras.

    Science.gov (United States)

    Strull, G; List, W F; Irwin, E L; Farnsworth, D L

    1972-05-01

    Over the past few years there has been growing interest shown in the rapidly maturing technology of totally solid-state imaging. This paper presents a synopsis of developments made in this field at the Westinghouse ATL facilities with emphasis on row-column organized monolithic arrays of diffused junction phototransistors. The complete processing sequence applicable to the fabrication of modern highdensity arrays is described from wafer ingot preparation to final sensor testing. Special steps found necessary for high yield processing, such as surface etching prior to both sawing and lapping, are discussed along with the rationale behind their adoption. Camera systems built around matrix array photosensors are presented in a historical time-wise progression beginning with the first 50 x 50 element converter developed in 1965 and running through the most recent 400 x 500 element system delivered in 1972. The freedom of mechanical architecture made available to system designers by solid-state array cameras is noted from the description of a bare-chip packaged cubic inch camera. Hybrid scan systems employing one-dimensional line arrays are cited, and the basic tradeoffs to their use are listed. PMID:20119094

  17. Retrieval of Mir Solar Array

    Science.gov (United States)

    Rutledge, Sharon K.; deGroh, Kim K.

    1999-01-01

    A Russian solar array panel removed in November 1997 from the non-articulating photovoltaic array on the Mir core module was returned to Earth on STS-89 in January 1998. The panel had been exposed to low Earth orbit (LEO) for 10 years prior to retrieval. The retrieval provided a unique opportunity to study the effects of the LEO environment on a functional solar array. To take advantage of this opportunity, a team composed of members from RSC-Energia (Russia), the Boeing Company, and the following NASA Centers--Johnson Space Center, Kennedy Space Center, Langley Research Center, Marshall Space Flight Center, and Lewis Research Center--was put together to analyze the array. After post-retrieval inspections at the Spacehab Facility at Kennedy in Florida, the array was shipped to Lewis in Cleveland for electrical performance tests, closeup photodocumentation, and removal of selected solar cells and blanket material. With approval from RSC-Energia, five cell pairs and their accompanying blanket and mesh material, and samples of painted handrail materials were selected for removal on the basis of their ability to provide degradation information. Sites were selected that provided different sizes and shapes of micrometeoroid impacts and different levels of surface contamination. These materials were then distributed among the team for round robin testing.

  18. Integrated Array/Metadata Analytics

    Science.gov (United States)

    Misev, Dimitar; Baumann, Peter

    2015-04-01

    Data comes in various forms and types, and integration usually presents a problem that is often simply ignored and solved with ad-hoc solutions. Multidimensional arrays are an ubiquitous data type, that we find at the core of virtually all science and engineering domains, as sensor, model, image, statistics data. Naturally, arrays are richly described by and intertwined with additional metadata (alphanumeric relational data, XML, JSON, etc). Database systems, however, a fundamental building block of what we call "Big Data", lack adequate support for modelling and expressing these array data/metadata relationships. Array analytics is hence quite primitive or non-existent at all in modern relational DBMS. Recognizing this, we extended SQL with a new SQL/MDA part seamlessly integrating multidimensional array analytics into the standard database query language. We demonstrate the benefits of SQL/MDA with real-world examples executed in ASQLDB, an open-source mediator system based on HSQLDB and rasdaman, that already implements SQL/MDA.

  19. Validity and reliability of rectus femoris ultrasound measurements: Comparison of curved-array and linear-array transducers

    Directory of Open Access Journals (Sweden)

    Kendra Hammond, MD

    2014-11-01

    Full Text Available Muscle-mass loss augers increased morbidity and mortality in critically ill patients. Muscle-mass loss can be assessed by wide linear-array ultrasound transducers connected to cumbersome, expensive console units. Whether cheaper, hand-carried units equipped with curved-array transducers can be used as alternatives is unknown. Accordingly, our primary aim was to investigate in 15 nondisabled subjects the validity of measurements of rectus femoris cross-sectional area by using a curved-array transducer against a linear-array transducer—the reference-standard technique. In these subjects, we also determined the reliability of measurements obtained by a novice operator versus measurements obtained by an experienced operator. Lastly, the relationship between quadriceps strength and rectus area recorded by two experienced operators with a curved-array transducer was assessed in 17 patients with chronic obstructive pulmonary disease (COPD. In nondisabled subjects, the rectus cross-sectional area measured with the curved-array transducer by the novice and experienced operators was valid (intraclass correlation coefficient [ICC]: 0.98, typical percentage error [%TE]: 3.7% and reliable (ICC: 0.79, %TE: 9.7%. In the subjects with COPD, both reliability (ICC: 0.99 and repeatability (%TE: 7.6% and 9.8% were high. Rectus area was related to quadriceps strength in COPD for both experienced operators (coefficient of determination: 0.67 and 0.70. In conclusion, measurements of rectus femoris cross-sectional area recorded with a curved-array transducer connected to a hand-carried unit are valid, reliable, and reproducible, leading us to contend that this technique is suitable for cross-sectional and longitudinal studies.

  20. 33 CFR 118.20 - Obtaining information.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Obtaining information. 118.20 Section 118.20 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.20 Obtaining information. Persons desiring information concerning...

  1. 38 CFR 21.5725 - Obtaining benefits.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Obtaining benefits. 21... benefits. (a) Actions required of the individual. In order to obtain benefits under the educational assistance and subsistence allowance program, an individual must— (1) File a claim for benefits with VA,...

  2. Working with Oligonucleotide Arrays.

    Science.gov (United States)

    Carvalho, Benilton S

    2016-01-01

    Preprocessing microarray data consists of a number of statistical procedures that convert the observed intensities into quantities that represent biological events of interest, like gene expression and allele-specific abundances. Here, we present a summary of the theory behind microarray data preprocessing for expression, whole transcriptome and SNP designs and focus on the computational protocol used to obtain processed data that will be used on downstream analyses. We describe the main features of the oligo Bioconductor package, an application designed to support oligonucleotide microarrays using the R statistical environment and the infrastructure provided by Bioconductor, allowing the researcher to handle probe-level data and interface with advanced statistical tools under a simplified framework. We demonstrate the use of the package by preprocessing data originated from three different designs. PMID:27008013

  3. THACO, a Test Facility for Characterizing the Noise Performance of Active Antenna Arrays

    CERN Document Server

    Woestenburg, E E M; Ruiter, M; Ivashina, M V; Witvers, R H

    2011-01-01

    This paper discusses an outdoor test facility for the noise characterization of active antenna arrays, using measurement results of array noise temperatures in the order of 50 K for a number of small aperture arrays. The measurement results are obtained by a Y-factor method with hot and a cold noise sources, with an absorber at room temperature as the hot load and the cold sky as the cold load. The effect of shielding the arrays by the test facility, with respect to noise and RFI from the environment, will also be discussed.

  4. Wavenumber response of Shanghai Seismic Array

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Seismic array can be traced back to 1950s when it mainly aimed at detecting and distinguishing the signals of nuclear explosion and seismic signals. The research on seismic array includes seismic array techniques and applications of array in geophysics. Array techniques involve array design and data processing methods (Anne, 1990). Nowadays, the continuous development of seismic array¢s theory could relate to many scientific issues in geophysical field (Tormod, 1989; Mykkeltveit, Bungum, 1984). Seismic array is mainly applied to detect weak events. The response characteristic of array is an important indication of array¢s detection ability. Therefore, when we study an array or construct an array, one of the neces-sary works is to calculate the response characteristics of the array (Harjes, 1990). The aperture and layout of array are two dominating geometrical features. The typical aperture of interna-tional array is generally from several to tens kilometers. For instance, arrays with aperture of dozens kilometers aperture are KSA, WRA, YKA, etc, while arrays with several kilometer aperture are ARC, FIN, GEE, etc. Moreo-ver, in the view of array¢s layout, NOR, GER, etc have circle layout, while WRA, YKA, etc have decussating layout. This paper mainly discusses the relation between deployment of array and wavenumber response. With the example of constructing Shanghai Seismic Array, this paper provides one practical solution to search the proper array deployment. In this paper, the simple delay beam technique is adopted to calculate the response characteris-tics of array. Certainly, the different processing methods have different result, but the result from the simple delay beam processing could be enough to reflect the feature of an array.

  5. Ready Reference. How To Obtain an ISBN; How To Obtain an ISSN; How To Obtain an SAN.

    Science.gov (United States)

    Koltay, Emery

    2003-01-01

    These three articles describe ISBNs (International Standard Book Numbers); ISSNs (International Standard Serial Numbers); and SANs (Standard Address Numbers), for organizations served by the book industry; and explains how to apply to obtain the appropriate numbers. (LRW)

  6. Transparent film with inverted conical microholes array for reflection enhancement

    Science.gov (United States)

    Lei, Biao; Liu, Hongzhong; Jiang, Weitao; Chen, Bangdao; Shi, Yongsheng; Yin, Lei; Liu, Xiaokang

    2016-04-01

    PDMS has been widely utilized for microfluidic chips and microchannel detections, as its good optical properties are the prerequisite to achieve accurate and efficient detection. However, it is difficult to obtain effective information for opaque liquids. With the development of microchannel detection for wider fields, it is imperative to obtain more comprehensive information of the observed objects by integrating high transmission with enhanced reflection. This article investigates reflection enhancement by Polydimethylsiloxane (PDMS) film with inverted conical microholes array. PDMS film with inverted conical microholes array is fabricated by replication from the silicon mold with inverted microcones array which is prepared by Inductively Coupled Plasma (ICP) etch tool. The monolayer PDMS film with inverted conical microholes array shows a two-fold effectively increase in reflection, approximately up to 15%, at a broad wavelength range of 637-1131 nm and 1214-1350 nm, compared with bare PDMS film. In addition, the reflection can be further enhanced by multilayered lamination of PDMS film with inverted conical microholes array, and the enhancement is also dependent on the lamination way, i.e., for bilayer laminations, the maximum reflection enhancement occurs when with face-to-back lamination, and 32.79% larger than that with back-to-face lamination. From the experiments, the maximum reflectivity of 8-layered PDMS films can obtain 64.4% while the maximum reflectivity of monolayer PDMS film barely has 17.5%. The transparent film with inverted conical microholes array for reflection enhancement may find a variety of applications in optical devices, microchips, and energy conservation technologies etc.

  7. Mathematical Simulating Model of Phased-Array Antenna in Multifunction Array Radar

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A mathematical simulating model of phased-array antenna in multifunction array radar has been approached in this paper, including the mathematical simulating model of plane phased-array pattern, the mathematical simulating model of directionality factor, the mathematical simulating model of array factor, the mathematical simulating model of array element factor and the mathematical simulating model of beam steering.

  8. A microspectrometer based on subwavelength metal nanohole array

    Science.gov (United States)

    Cui, Jun; Xia, Liangping; Yang, Zheng; Yin, Lu; Zheng, Guoxing; Yin, Shaoyun; Du, Chunlei

    2014-11-01

    Catering to the active demand of the miniaturization of spectrometers, a simple microspectrometer with small size and light weight is presented in this paper. The presented microspectrometer is a typical filter-based spectrometer using the extraordinary optical transmission property of subwavelength metal hole array structure. Different subwavelength metal nanohole arrays are designed to work as different filter units obtained by changing the lattice parameters. By processing the filter spectra with a unique algorithm based on sparse representation, the proposed spectrometer is demonstrated to have the capability of high spectral resolution and accuracy. Benefit for the thin filmed feature, the microspectrometer is expected to find its application in integrated optical systems.

  9. Active Control of Solar Array Dynamics During Spacecraft Maneuvers

    Science.gov (United States)

    Ross, Brant A.; Woo, Nelson; Kraft, Thomas G.; Blandino, Joseph R.

    2016-01-01

    Recent NASA mission plans require spacecraft to undergo potentially significant maneuvers (or dynamic loading events) with large solar arrays deployed. Therefore there is an increased need to understand and possibly control the nonlinear dynamics in the spacecraft system during such maneuvers. The development of a nonlinear controller is described. The utility of using a nonlinear controller to reduce forces and motion in a solar array wing during a loading event is demonstrated. The result is dramatic reductions in system forces and motion during a 10 second loading event. A motion curve derived from the simulation with the closed loop controller is used to obtain similar benefits with a simpler motion control approach.

  10. CCD camera full range pH sensor array.

    Science.gov (United States)

    Safavi, A; Maleki, N; Rostamzadeh, A; Maesum, S

    2007-01-15

    Changes in colors of an array of optical sensors that responds in full pH range were recorded using a CCD camera. The data of the camera were transferred to the computer through a capture card. Simple software was written to read the specific color of each sensor. In order to associate sensor array responses with pH values, a number of different mathematics and chemometrics methods were investigated and compared. The results show that the use of "Microsoft Excel's Solver" provides results which are in very good agreement with those obtained with chemometric methods such as artificial neural network (ANN) and partial least square (PLS) methods. PMID:19071333

  11. Lipid bilayer array for simultaneous recording of ion channel activities

    Science.gov (United States)

    Hirano-Iwata, Ayumi; Nasu, Tomohiro; Oshima, Azusa; Kimura, Yasuo; Niwano, Michio

    2012-07-01

    This paper describes an array of stable and reduced-solvent bilayer lipid membranes (BLMs) formed in microfabricated silicon chips. BLMs were first vertically formed simultaneously and then turned 90° in order to realize a horizontal BLM array. Since the present BLMs are mechanically stable and robust, the BLMs survive this relatively tough process. Typically, a ˜60% yield in simultaneous BLM formation over 9 sites was obtained. Parallel recordings of gramicidin channel activities from different BLMs were demonstrated. The present system has great potential as a platform of BLM-based high throughput drug screening for ion channel proteins.

  12. Field emission properties of an array of pyramidal structures

    Energy Technology Data Exchange (ETDEWEB)

    De Assis, Thiago A [Departamento de QuImica, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Borondo, F [Departamento de QuImica, Instituto Mixto de Ciencias Matematicas CSIC-UAM-UC3M-UCM, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); De Castilho, C M C; Brito Mota, F [Grupo de Fisica de SuperfIcies e Materiais, Instituto de Fisica, Universidade Federal da Bahia, Campus Universitario da Federacao, 40210-340, Salvador, BA (Brazil); Benito, R M, E-mail: t.albuquerque@uam.e, E-mail: f.borondo@uam.e, E-mail: caio@ufba.b, E-mail: fbmota@ufba.b, E-mail: rosamaria.benito@upm.e [Grupo de Sistemas Complejos, Departamento de Fisica y Mecanica, Escuela Tecnica Superior de Ingenieros Agronomos, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain)

    2009-10-07

    The properties and efficiency of the emission current density produced by a metallic array of pyramidal structures are investigated. The theoretical results obtained by numerical integration of the corresponding Laplace equation using a finite differences scheme offer useful information for the optimization of field emission devices based on cathodes with this geometry. Our study shows that the inter-pyramidal distance strongly affects the current density, and even more important for this issue is the protrusion characteristics of these structures. Another relevant, although less important, parameter determining this density is the anode-cathode distance. The effect of the array characteristics on the maximum local electric field intensity is also discussed.

  13. Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, C. N.; Volyar, A. V. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Yavorsky, M. A. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Universite Bordeaux and CNRS, LOMA, UMR 5798, FR-33400 Talence (France)

    2011-12-15

    We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

  14. Method of array shape calibration based on time delay estimation using two auxiliary sources

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; WU Lixin; CUI Jie; Jim Lynch; Arthur Newhall

    2007-01-01

    As for a flexible horizontal array deployed in the sea, it is difficult to obtain each sensor's precise relative position. Therefore a method of array shape calibration is proposed.The method is described as follows. Firstly two separate auxiliary sources are deployed. Secondly time delay of each sensor's received signal is estimated. Finally, with the aid of GPS location of the sources and the horizontal array, relative sensor positions of the horizontal array can be determined. The estimation of relative sensor positions is unbiased. Simultaneously,simulation analysis has been done to estimate its standard variance, and the optimal flare angle of the two sources has been derived. Data of 2001 Asian Sea International Experiment have been used to validate the method. After array calibration, measured source azimuth angle agrees with the real one, and measured array gain agrees with the theoretical gain. In conclusion, the theoretical and experimental results both show that the method can determine each sensor's relative position precisely.

  15. Study and operating conditions of HTS Josephson arrays for metrological application

    International Nuclear Information System (INIS)

    We report an experimental study of metrological properties of high-temperature superconductor arrays, made of shunted bicrystal YBCO Josephson junctions. The work is mainly based on a direct comparison against a low temperature array. Owing to the high sensitivity of the measurements, we observed at nanovolt level the changes in the HTS array voltage on a step. A precise estimate of the dependence of the HTS array step width on operating conditions was obtained. Differences were observed with respect to the results of low sensitivity techniques, confirming that our method is necessary in the study of HTS arrays for metrology. The high sensitivity analysis was also applied in the derivation of the temperature dependence of the critical current, providing insights on the behavior of the HTS array

  16. Substrate integrated antennas and arrays

    CERN Document Server

    Cheng, Yu Jian

    2015-01-01

    Substrate Integrated Antennas and Arrays provides a single source for cutting-edge information on substrate integrated circuits (SICs), substrate integrated waveguide (SIW) feeding networks, SIW slot array antennas, SIC traveling-wave antennas, SIW feeding antennas, SIW monopulse antennas, and SIW multibeam antennas. Inspired by the author's extensive research, this comprehensive book:Describes a revolutionary SIC-based antenna technique with the potential to replace existing antenna technologiesExamines theoretical and experimental results connected to electrical and mechanical performanceExp

  17. TV-SAT solar array

    Energy Technology Data Exchange (ETDEWEB)

    Urbain, G.; Rinn, C.; Bastard, J.L.

    1982-06-01

    The electrical and mechanical performance of the TV-SAT direct television broadcasting satellite is described. The 4.5 kW end of life 7.5yr array contains 43,200 back surface reflector solar cells. The first, 3.1 kW, array consists of two identical wings, providing power during transfer and geostationary orbit. Each wing is made up of four carbon fiber panels. The outboard panel of each wing is deployed at 90 deg in transfer orbit, during which the satellite is three axis stabilized.

  18. Phased arrays: inline flow line hub inspection using phased arrays

    NARCIS (Netherlands)

    Bloom, J.G.P.; Chougrani, K.; Rundberg, H.; Oldenziel, G.; Deleye, X.; Martina, Q.

    2011-01-01

    The feasibility of the inspection of flow line hubs using the phased array technique was investigated to determine the surface area of the seal area degraded by corrosion. A clean model of the hub was simulated to gain insight into the geometrical echoes and to determine the area covered by the ultr

  19. Numerical simulation of crosstalk in reduced pitch HgCdTe photon-trapping structure pixel arrays.

    Science.gov (United States)

    Schuster, Jonathan; Bellotti, Enrico

    2013-06-17

    We have investigated crosstalk in HgCdTe photovoltaic pixel arrays employing a photon trapping (PT) structure realized with a periodic array of pillars intended to provide broadband operation. We have found that, compared to non-PT pixel arrays with similar geometry, the array employing the PT structure has a slightly higher optical crosstalk. However, when the total crosstalk is evaluated, the presence of the PT region drastically reduces the total crosstalk; making the use of the PT structure not only useful to obtain broadband operation, but also desirable for reducing crosstalk in small pitch detector arrays. PMID:23787659

  20. Functional nanostructured titanium nitride films obtained by sputtering magnetron

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, O. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain)]. E-mail: olgas@icmm.csic.es; Hernandez-Velez, M. [Instituto de Ciencia de Materiales de Madrid (CSIC), or Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain); Dept. Fisica Aplicada C-XII, Universidad Autonoma, Cantoblanco 28049 Madrid (Spain); Navas, D. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain); Auger, M.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM-CSIC), Avda. Gregorio, del Amo 8, 28040 Madrid (Spain); Baldonedo, J.L. [Centro de Microscopia Electronica y Citometria de la Universidad Complutense de, Madrid (Spain); Sanz, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain); Pirota, K.R. [Instituto de Ciencia de Materiales de Madrid (CSIC), or Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain); Vazquez, M. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz no3, Cantoblanco, 28049 Madrid (Spain)

    2006-01-20

    Development of new methods in the formation of hollow structures, in particular, nanotubes and nanocages are currently generating a great interest as a consequence of the growing relevance of these nanostructures on many technological fields, ranging from optoelectronics to biotechnology. In this work, we report the formation of titanium nitride (TiN) nanotubes and nanohills via reactive sputtering magnetron processes. Anodic Alumina Membranes (AAM) were used as template substrates to grow the TiN nanostructures. The AAM were obtained through electrochemical anodization processes by using oxalic acid solutions as electrolytes. The nanotubes were produced at temperatures below 100 deg. C, and using a pure titanium (99.995%) sputtering target and nitrogen as reactive gas. The obtained TiN thin films showed surface morphologies adjusted to pore diameter and interpore distance of the substrates, as well as ordered arrays of nanotubes or nanohills depending on the sputtering and template conditions. High Resolution Scanning Electron Microscopy (HRSEM) was used to elucidate both the surface order and morphology of the different grown nanostructures. The crystalline structure of the samples was examined using X-ray Diffraction (XRD) patterns and their qualitative chemical composition by using X-ray Energy Dispersive Spectroscopy (XEDS) in a scanning electron microscopy.

  1. Complete Moment Convergence for Weighted Sums of Arrays of Rowwise NA Random Variables

    Institute of Scientific and Technical Information of China (English)

    Dehua QIU; Pingyan CHEN

    2012-01-01

    In this paper we obtain some new results on complete moment convergence for weighted sums of arrays of rowwise NA random variables.Our results improve and extend some well known results from the literature.

  2. Treatment of biomass to obtain ethanol

    Science.gov (United States)

    Dunson, Jr., James B.; Elander, Richard T.; Tucker, III, Melvin P.; Hennessey, Susan Marie

    2011-08-16

    Ethanol was produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

  3. 47 CFR 54.615 - Obtaining services.

    Science.gov (United States)

    2010-10-01

    ... provided under § 54.621, that the requester cannot obtain toll-free access to an Internet service provider... thing of value; (6) If the service or services are being purchased as part of an aggregated...

  4. Obtaining useful information from expert based sources.

    OpenAIRE

    Slawson, D. C.; Shaughnessy, A. F.

    1997-01-01

    Clinicians rely heavily on expert based systems-consultation with colleagues, journal reviews and textbooks, and continuing education activities-to obtain new information. The usefulness of sources such as these depends on the relevance and validity of the information and the work it takes to obtain it. Useful information can be distinguished from the useless by asking three questions: Does the information focus on an outcome that my patients care about? Is the issue common to my practice, an...

  5. Critical Heegaard surfaces obtained by amalgamation

    CERN Document Server

    Lee, Jung Hoon

    2011-01-01

    Critical surfaces are defined by Bachman as topological index 2 surfaces, generalizing incompressible surfaces and strongly irreducible surfaces. In this paper we give a condition to obtain critical Heegaard surfaces by amalgamation. As a special case, we obtain critical Heegaard surfaces by boundary stabilization. It gives critical Heegaard surfaces of non-minimal genus, for 3-manifolds which do not admit distinct Heegaard splittings (up to isotopy).

  6. Higher-order Dirac solitons in binary waveguide arrays

    International Nuclear Information System (INIS)

    We study optical analogues of higher-order Dirac solitons (HODSs) in binary waveguide arrays. Like higher-order solitons obtained from the well-known nonlinear Schrödinger equation governing the pulse propagation in an optical fiber, these HODSs have amplitude profiles which are numerically shown to be periodic over large propagation distances. At the same time, HODSs possess some unique features. Firstly, the period of a HODS depends on its order parameter. Secondly, the discrete nature in binary waveguide arrays imposes the upper limit on the order parameter of HODSs. Thirdly, the order parameter of HODSs can vary continuously in a certain range. - Highlights: • Higher-order Dirac solitons in nonlinear binary waveguide arrays are numerically demonstrated. • Amplitude profiles of higher-order Dirac solitons are periodic during propagation. • The period of higher-order Dirac solitons decreases when the soliton order increases

  7. Microstrip Phased Array Antennas Printed on Inclined Planes

    Directory of Open Access Journals (Sweden)

    A. Papiernik

    1996-06-01

    Full Text Available This paper presents an analysis of the electromagnetic field radiated by micro-strip patch antennas printed on inclined surfaces. The theoretical approach allows to apply spatial rotations to each source. The computer simulation developed permits us to experiment different antenna structures and two original realisations are proposed: a 2-element array printed on two inclined planes and a 4-element array laid out on a pyramidal surface. In addition, it enables the choice of the phase applied to each radiator to produce a beam deflection function. A good accuracy is obtained between theoretical and experimental results. The aim of this study is to optimise the parameters of such antennas to achieve the desired radiation patterns, from printed phased arrays on conformal surfaces. We also present the theoretical behaviour of a octagonal pyramid.

  8. A Broadband Conformal Phased Array Antenna on Spherical Surface

    Directory of Open Access Journals (Sweden)

    Dan Sun

    2014-01-01

    Full Text Available A Ku-band wideband conformal array antenna with 13×19 elements is presented in the paper. The array has a spherical structure, and its element is a proximity-coupled stacked patches antenna with a cavity-backed ground plane. The stacked patches and the cavity produce multiple coupled resonances, which enhance the bandwidth of the element extremely. A simulated model with the reasonable dimensions is framed with the coupling analyses, and the effective simulated results and good computing efficiency are obtained simultaneously. The measured results of the center embedded element in the whole array show a bandwidth exceeding 40% VSWR<2, which is close to the simulated matching performance.

  9. Resistor array infrared nonuniformity correction based on sparse grid

    Science.gov (United States)

    He, Xudong; Qiu, Jiang; Zhang, Qiao; Du, Huijie; Zhao, Hongming

    2013-10-01

    Resistor array plays a vital role in emulation of the IR control and guide system. However, its serious nonuniformity confines the range of its application. Therefore, in order to obtain an available IR image, nonuniformity correction (NUC) is necessary. The traditional method is sparse grid and flood which only take the array's nonuniformity into account. In this paper we present an improved sparse grid method which considers the whole system which affects the array's nonuniformity by dividing the NUC process into different gray levels. In each gray level, we can take two points or several points to calculate the nonuniformity of every block which is divided before correction. After that, we can have several characteristic curves which will be operated with curve fitting. By this means, we will correct the nonuniformity. At last, through the experiment of a number of images, we find the residual nonuniformity associated with random noise is about 0.2% after the correction.

  10. Stochastic resonance in a parallel array of linear elements

    Institute of Scientific and Technical Information of China (English)

    Dong Xiao-Juan

    2009-01-01

    This paper studies stochastic resonance (SR) phenomenon in a parallel array of linear elements with noise. Employing the signal-to-noise ratio (SNR) theory, it obtains the output SNR, and investigates the effects on the output SNR of the system with signal-independent noise and signal-dependent noise respectively. Numerical results show: the curve of the output SNR is monotone with signal-independent noise; whereas SR appears with signal-dependent noise. Moreover, the output SNR enhances rapidly with the increase of N which is the number of elements in this parallel array linear system. This result may provide smart array of simple linear sensors which are capable of acting as noise-aided amplifiers.

  11. Improvement for the steering performance of liquid crystal phased array

    Institute of Scientific and Technical Information of China (English)

    SONG Yan; KONG Ling-jiang; CHEN Jun; ZHU Ying; YANG Jian-yu

    2009-01-01

    Optical phased array technology is introduced and the steering performances of liquid crystal phased array are discussed, several factors affecting the beam steering performances arc analyzed completely, also simple models for some typical factors are developed. Then, a new method based on iterating and modifying the output phase pattern of liquid crystal phase shifters is proposed. Using this method, the modified voltages applied on electrodes of liquid crystal phase shifters can be obtained, after applying the voltages, the influence of factors can be compensated to some extent; the steering angle accu-racy and efficiency with liquid crystal phased array can be improved. Through the simulation for the angle range from 0° to -1°, the error of steering angle can be reduced three orders of magnitude, and the efficiency can be increased almost 30% after several iterations.

  12. Remanence Properties and Magnetization Reversal Mechanism of Fe Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Bo; LIU Qing-Fang; XUE De-Sheng; LI Fa-Shen

    2004-01-01

    @@ Remanence properties and magnetization reversal mechanism of Fe nanowire arrays with diameters 16 nm and130nm are studied. Isothermal remanent magnetization curves show that the contribution of irreversible magnetization decreases when the diameter changes from 16nm to 130nm. The remanence coercivities of these nanowires obtained in dc-demagnetization curve are about 2400 Oe and 800 Oe, respectively. The magnetization reversal mechanism is different in these two samples. For the nanowire array with diameter 16nm, both the nucleation and the pinning have effects on magnetization reversal mechanism, and the pinning field (about 2500Oe) is larger than the nucleation field (about 2200 Oe). However, for the nanowire array with diameter 130nm,the magnetization reversal mechanism is dominated by the pinning effect of domain walls.

  13. Modeling and simulation of Microstrip patch array for smart antennas

    Directory of Open Access Journals (Sweden)

    K.Meena alias Jeyanthi

    2010-01-01

    Full Text Available The aim of the paper is two fold. One is to design and simulate an antenna array suitable for wireless applications and the other is the design of beamforming algorithm. In this paper, the first module presents the design of multiple microstrip rectangular patch elements suitable for beamforming technique in wireless applications in the range of 1.8 - 2.4 GHz. By designing 1x8 patch array, it is possible to achieve 15 dB gain and 58% more directivity compared to the conventional patches. The second module suggests a NLVFF-RLS algorithm for beamforming technique to concentrate the power in the desired direction and nullify the power in the interferer direction with HPBW of 13dB.The results are analyzed for the scanning sector of -60° to 60°. The modeling and simulation of antenna array is obtained using Agilent’s ADS. The beamforming algorithm is designed in Matlab.

  14. Key Science Observations of AGNs with KaVA Array

    CERN Document Server

    Kino, Motoki; Zhao, Guang-Yao; Sohn, Bong Won

    2015-01-01

    KaVA (KVN and VERA Array) is a new combined VLBI array with KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). First, we briefly review the imaging capabilities of KaVA array which actually achieves more than three times better dynamic range than that achieved by VERA alone. The KaVA images clearly show detailed structures of extended radio jets in AGNs. Next, we represent the key science program to be led by KaVA AGN sub working group. We will conduct the monitoring observations of Sgr A* and M87 because of the largeness of their central super-massive black hole angular sizes. The main science goals of the program are (i) testing magnetically-driven-jet paradigm by mapping velocity fields of the M87 jet, and (ii) obtaining tight constraints on physical properties of radio emitting region in Sgr A*.

  15. Higher-order Dirac solitons in binary waveguide arrays

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Truong X., E-mail: Truong.Tran@mpl.mpg.de [Department of Physics, Le Quy Don University, 236 Hoang Quoc Viet str., 10000 Hanoi (Viet Nam); Max Planck Institute for the Science of Light, Günther-Scharowsky str. 1, 91058 Erlangen (Germany); Duong, Dũng C. [Department of Physics, Le Quy Don University, 236 Hoang Quoc Viet str., 10000 Hanoi (Viet Nam)

    2015-10-15

    We study optical analogues of higher-order Dirac solitons (HODSs) in binary waveguide arrays. Like higher-order solitons obtained from the well-known nonlinear Schrödinger equation governing the pulse propagation in an optical fiber, these HODSs have amplitude profiles which are numerically shown to be periodic over large propagation distances. At the same time, HODSs possess some unique features. Firstly, the period of a HODS depends on its order parameter. Secondly, the discrete nature in binary waveguide arrays imposes the upper limit on the order parameter of HODSs. Thirdly, the order parameter of HODSs can vary continuously in a certain range. - Highlights: • Higher-order Dirac solitons in nonlinear binary waveguide arrays are numerically demonstrated. • Amplitude profiles of higher-order Dirac solitons are periodic during propagation. • The period of higher-order Dirac solitons decreases when the soliton order increases.

  16. New air fluorescence detectors employed in the Telescope Array experiment

    CERN Document Server

    Tokuno, H; Takeda, M; Kadota, K; Ikeda, D; Chikawa, M; Fujii, T; Fukushima, M; Honda, K; Inoue, N; Kakimoto, F; Kawana, S; Kido, E; Matthews, J N; Nonaka, T; Ogio, S; Okuda, T; Ozawa, S; Sagawa, H; Sakurai, N; Shibata, T; Taketa, A; Thomas, S B; Tomida, T; Tsunesada, Y; Udo, S; Abu-zayyad, T; Aida, R; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Cho, E J; Cho, W R; Fujii, H; Fukuda, T; Gorbunov, D; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Iguchi, T; Ikuta, K; Ishii, T; Ishimori, R; Ivanov, D; Iwamoto, S; Jui, C C H; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kim, H B; Kim, H K; Kim, J H; Kim, J H; Kitamoto, K; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lim, S I; Machida, S; Martens, K; Martineau, J; Matsuda, T; Matsuura, T; Matsuyama, T; Myers, I; Minamino, M; Miyata, K; Miyauchi, H; Murano, Y; Nakamura, T; Nam, S W; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Oshima, A; Park, I H; Pshirkov, M S; Rodriguez, D; Roh, S Y; Rubtsov, G; Ryu, D; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzuki, S; Takahashi, Y; Takita, M; Tanaka, H; Tanaka, K; Tanaka, M; Thomson, G B; Tinyakov, P; Tkachev, I; Troitsky, S; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Wood, M; Yamakawa, Y; Yamaoka, H; Yamazaki, K; Yang, J; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2012-01-01

    Since 2007, the Telescope Array (TA) experiment, based in Utah, USA, has been observing ultra high energy cosmic rays to understand their origins. The experiment involves a surface detector (SD) array and three fluorescence detector (FD) stations. FD stations, installed surrounding the SD array, measure the air fluorescence light emitted from extensive air showers (EASs) for precise determination of their energies and species. The detectors employed at one of the three FD stations were relocated from the High Resolution Fly's Eye experiment. At the other two stations, newly designed detectors were constructed for the TA experiment. An FD consists of a primary mirror and a camera equipped with photomultiplier tubes. To obtain the EAS parameters with high accuracies, understanding the FD optical characteristics is important. In this paper, we report the characteristics and installation of new FDs and the performances of the FD components. The results of the monitored mirror reflectance during the observation ti...

  17. Slow and fast light in SOA-EA structures for phased-array antennas

    DEFF Research Database (Denmark)

    Sales, S.; Öhman, Filip; Bermejo, A.;

    We present an SOA-EA structure for controlling the phase and amplitude of optically fed phased-array antennas. Phase shifts of 40 degrees are obtained through slow and fast light effects by changing only the reverse voltage.......We present an SOA-EA structure for controlling the phase and amplitude of optically fed phased-array antennas. Phase shifts of 40 degrees are obtained through slow and fast light effects by changing only the reverse voltage....

  18. Tunable Antireflection Layers for Planar Bolometer Arrays

    Science.gov (United States)

    Brown, Ari-David; Chuss, David; Woolack, Edward; Chervenak, James; Henry, Ross; Wray, James

    2007-01-01

    It remains a challenge to obtain high-efficiency coupling of far-infrared through millimeter radiation to large-format detector arrays. The conventional approach of increasing detector coupling is to use reflective backshorts. However, this approach often results in excessive systematic errors resulting from reflections off the backshort edge. An alternate approach to both increasing quantum efficiency and reducing systematics associated with stray light is to place an antireflective coating near the front surface of the array. When incorporated with a resistive layer and placed behind the detector focal plane, the AR coating can serve to prevent optical ghosting by capturing radiation transmitted through the detector. By etching a hexagonal pattern in silicon, in which the sizes of the hexes are smaller than the wavelength of incident radiation, it is possible to fabricate a material that has a controllable dielectric constant, thereby allowing for simple tunable optical device fabrication. To this end, we have fabricated and tested tunable silicon "honeycomb" AR layers and AR/resistive layer devices. These devices were fabricated entirely out of silicon in order to eliminate problems associated with differential contraction upon detector cooling.

  19. Light weight digital array SAR

    NARCIS (Netherlands)

    Otten, M.; Maas, N.; Bolt, R.; Anitori, L.

    2010-01-01

    A light weight SAR has been designed, suitable for short range tactical UAVs, consisting of a fully digital receive array, and a very compact active transmit antenna. The weight of the complete RF front is expected to be below 3 kg, with a power consumption below 30 W. This X-band system can provide

  20. PHARUS : PHased ARray Universal SAR

    NARCIS (Netherlands)

    Paquay, M.H.A.; Vermeulen, B.C.B.; Koomen, P.J.; Hoogeboom, P.; Snoeij, P.; Pouwels, H.

    1996-01-01

    In the Netherlands, a polarimetric C-band aircraft SAR (Synthetic Aperture Radar) has been developed. The project is called PHARUS, an acronm for PHased ARray Universal SAR. This instrument serves remote sensing applications. The antenna system contains 48 active modules (expandable to 96). A module

  1. Photoelectrochemistry of Semiconductor Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, Thomas E; Redwing, Joan M

    2009-11-10

    This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

  2. High density arrays of micromirrors

    Energy Technology Data Exchange (ETDEWEB)

    Folta, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Decker, J. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kolman, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lee, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brase, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    1999-02-01

    We established and achieved our goal to (1) fabricate and evaluate test structures based on the micromirror design optimized for maskless lithography applications, (2) perform system analysis and code development for the maskless lithography concept, and (3) identify specifications for micromirror arrays (MMAs) for LLNL's adaptive optics (AO) applications and conceptualize new devices.

  3. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2001-01-01

    This book gives an introduction to the possibilities of radar technology based on active array antennas, giving examples of modern practical systems. There are many valuable lessons presented for designers of future high standard multifunction radar systems for military and civil applications. The book will appeal to graduate level engineers, researchers, and managers in the field of radar, aviation and space technology.

  4. Early Observations with the Expanded Owens Valley Solar Array

    Science.gov (United States)

    Gary, Dale E.

    2016-05-01

    The Expanded Owens Valley Solar Array (EOVSA) is a newly expanded and upgraded, solar-dedicated radio array consisting of 13 antennas of 2.1 m diameter equipped with receivers designed to cover the 1-18 GHz frequency range. Two large (27-m diameter) dishes are being outfitted with He-cooled receivers for use in calibration of the small dishes. During 2015, the array obtained observations from dozens of flares in total power mode on 8 antennas. Since February 2016, it has begun taking solar data on all 13 small antennas with full interferometric correlations, as well as calibration observations with the first of the two large antennas equipped with its He-cooled receiver. The second He-cooled receiver is nearly complete, and will be available around the time of the meeting. We briefly review the commissioning activities leading up to full operations, including polarization and gain measurements and calibration methods, and resulting measures of array performance. We then present some early imaging observations with the array, emphasizing the remarkable temporal and spectral resolution of the instrument, together with joint RHESSI hard X-ray and SDO EUV observations.

  5. Compressive Sensing Based Design of Sparse Tripole Arrays.

    Science.gov (United States)

    Hawes, Matthew; Liu, Wei; Mihaylova, Lyudmila

    2015-12-10

    This paper considers the problem of designing sparse linear tripole arrays. In such arrays at each antenna location there are three orthogonal dipoles, allowing full measurement of both the horizontal and vertical components of the received waveform. We formulate this problem from the viewpoint of Compressive Sensing (CS). However, unlike for isotropic array elements (single antenna), we now have three complex valued weight coefficients associated with each potential location (due to the three dipoles), which have to be simultaneously minimised. If this is not done, we may only set the weight coefficients of individual dipoles to be zero valued, rather than complete tripoles, meaning some dipoles may remain at each location. Therefore, the contributions of this paper are to formulate the design of sparse tripole arrays as an optimisation problem, and then we obtain a solution based on the minimisation of a modified l1 norm or a series of iteratively solved reweighted minimisations, which ensure a truly sparse solution. Design examples are provided to verify the effectiveness of the proposed methods and show that a good approximation of a reference pattern can be achieved using fewer tripoles than a Uniform Linear Array (ULA) of equivalent length.

  6. Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays.

    Science.gov (United States)

    Trucco, Andrea; Traverso, Federico; Crocco, Marco

    2015-01-01

    For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

  7. Compressive Sensing Based Design of Sparse Tripole Arrays

    Directory of Open Access Journals (Sweden)

    Matthew Hawes

    2015-12-01

    Full Text Available This paper considers the problem of designing sparse linear tripole arrays. In such arrays at each antenna location there are three orthogonal dipoles, allowing full measurement of both the horizontal and vertical components of the received waveform. We formulate this problem from the viewpoint of Compressive Sensing (CS. However, unlike for isotropic array elements (single antenna, we now have three complex valued weight coefficients associated with each potential location (due to the three dipoles, which have to be simultaneously minimised. If this is not done, we may only set the weight coefficients of individual dipoles to be zero valued, rather than complete tripoles, meaning some dipoles may remain at each location. Therefore, the contributions of this paper are to formulate the design of sparse tripole arrays as an optimisation problem, and then we obtain a solution based on the minimisation of a modified l 1 norm or a series of iteratively solved reweighted minimisations, which ensure a truly sparse solution. Design examples are provided to verify the effectiveness of the proposed methods and show that a good approximation of a reference pattern can be achieved using fewer tripoles than a Uniform Linear Array (ULA of equivalent length.

  8. Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Andrea Trucco

    2015-06-01

    Full Text Available For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed. In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

  9. Vision communications based on LED array and imaging sensor

    Science.gov (United States)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  10. Obtaining of ceramics biphasic dense and porous

    International Nuclear Information System (INIS)

    Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

  11. Obtain of uranium concentrates from fertil liquids

    International Nuclear Information System (INIS)

    This research tried to encounter the form to remove uranium from the rock in the best way, for that it was used different process like leaching, extraction, concentration and precipitation. To leach the mineral was chosen basic leaching, using a mixture of carbonate-sodium bicarbonate, this method is more adequated for the basic nature of the mineral. In extraction was used specific uranium ionic interchanges, so was chosen a tertiary amine like Alamina 336. The concentration phase is intimately binding with the extraction by ionic interchange, for the capability of resine's extraction to obtain concentrated liquids. When the liquids were obtained with high concentration of uranium in the same time were purified and then were precipitated, for that we employed a precipitant agent like: Sodium hydroxide, Amonium hydroxide, Magnesium hydroxide, Hydrogen peroxide and phosphates. With all concentrates we obtain the YELLOW CAKE

  12. A system for obtaining an optical spectrum

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a system for obtaining an optical spectrum 648 of analytes in a fluid sample, wherein a porous filter 602a, 602b is arranged so that the fluid sample may be placed onto a first region of the porous filter, and a SERS-active material 610a, 610b having a SERS...... second region. Thereby, the porous filter enables that the fluid sample is filtered so that only sufficiently small entities in the fluid sample reach the second region where they may be probed so that an optical spectrum related to the analytes in the filtered sample may be obtained. The optical system...... also comprises a light source 634, a light detector 642, and the optical analysis system is arranged for obtaining the optical spectrum 648 of the analytes adjacent to the SERS-active material 610a, 610b exclusively from the second region of the porous filter 602a, 602b....

  13. Air Shower Radio Emission with Energy E$_0$$\\geq$10$^{19}$ eV by Yakutsk Array Data

    CERN Document Server

    Knurenko, S P

    2016-01-01

    The paper presents short technical description of Yakutsk Radio Array and some preliminary results obtained from measurements of radio emission at 32 MHz frequency induced by air shower particles with energy {\\epsilon}$\\geq$1$\\cdot$10$^{19}$ eV. The data obtained at Yakutsk array in 1987-1989 (first set of measurements) and 2009-2014 (new set of measurements). For the first time, at Yakutsk array radio emission from air shower with energy > 10$^{19}$ eV was registered including the shower with highest energy ever registered at Yakutsk array with energy $\\sim$2$\\cdot$10$^{20}$ eV.

  14. Polymeric Cantilever Arrays for Biosensing Applications

    DEFF Research Database (Denmark)

    Calleja, M.; Tamayo, J.; Johansson, Alicia;

    2003-01-01

    We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material...... properties. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. The method allows obtaining well-controlled and uniform mechanical properties of the cantilevers. The elastic constant of the cantilevers was measured, and their dynamic response...... was studied. Characterization of the devices shows that they are suitable for both static and dynamic measurements for biochemical detection in either air or liquid environments. The sensor was applied to monitoring of the immobilization process of cystamine on a gold-coated SU-8 cantilever....

  15. Calibration of the Cherenkov Telescope Array

    CERN Document Server

    Gaug, Markus; Berge, David; Reyes, Raquel de los; Doro, Michele; Foerster, Andreas; Maccarone, Maria Concetta; Parsons, Dan; van Eldik, Christopher

    2015-01-01

    The construction of the Cherenkov Telescope Array is expected to start soon. We will present the baseline methods and their extensions currently foreseen to calibrate the observatory. These are bound to achieve the strong requirements on allowed systematic uncertainties for the reconstructed gamma-ray energy and flux scales, as well as on the pointing resolution, and on the overall duty cycle of the observatory. Onsite calibration activities are designed to include a robust and efficient calibration of the telescope cameras, and various methods and instruments to achieve calibration of the overall optical throughput of each telescope, leading to both inter-telescope calibration and an absolute calibration of the entire observatory. One important aspect of the onsite calibration is a correct understanding of the atmosphere above the telescopes, which constitutes the calorimeter of this detection technique. It is planned to be constantly monitored with state-of-the-art instruments to obtain a full molecular and...

  16. FEBA - flooding experiments with blocked arrays

    International Nuclear Information System (INIS)

    This report presents typical data and a limited heat transfer analysis of test series V through VIII from an experimental thermal-hydraulic program of Flooding Experiments with Blocked Arrays (FEBA). The experiments consisted of separate effect tests on a full-length 5x5 rod bundle of PWR fuel rod dimensions utilizing electrically heated rods with a cosine power profile approximated by 7 steps of different specific power. Eight test series were performed under idealized reflood conditions using forced feed and system pressure as parameters without the inclusion of the effects of a reactor cooling system. The individual test series were conducted to study the effect of grid spacers and of coplanar blockages of different blockage ratios with and without bypass on the reflood heat transfer. The purpose of the investigations was to obtain an insight into the most important heat transfer mechanisms and to broaden the data base for the development and assessment of improved thermal-hydraulic models. (orig.)

  17. A Two Element Plasma Antenna Array

    Directory of Open Access Journals (Sweden)

    F. Sadeghikia

    2013-10-01

    Full Text Available This theoretical study presents the characteristics of plasma monopole antennas in the VHF/UHF range using finite difference time domain (FDTD simulation. Results show that more broadband characteristics can be obtained by increasing the diameter of the plasma tube and that the minor lobes diminish in intensity as diameter increases. Furthermore, the nulls are replaced by low level radiation. Since the collision frequency, which is a function of gas pressure, represents the loss mechanism of plasma, decreasing its value increases the gain and radar cross section (RCS of the antenna. Theoretical modeling shows that at higher plasma frequencies with respect to the signal frequency, the gain and radar cross section of the plasma antenna are high enough and that the impedance curves are altered as the plasma frequency varies. Using these preliminary studies, mutual impedance and gain of a broadside array of two parallel side-by-side plasma elements is presented.

  18. Arrayed primer extension in the "array of arrays" format: a rational approach for microarray-based SNP genotyping

    DEFF Research Database (Denmark)

    Klitø, Niels G F; Tan, Qihua; Nyegaard, Mette;

    2007-01-01

    This study provides a new version of the arrayed primer extension (APEX) protocol adapted to the 'array of arrays' platform using an instrumental setup for microarray processing not previously described. The primary aim of the study is to implement a system for rational cost-efficient genotyping ...

  19. Obtaining the Andersen's chart, triangulation algorithm

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    Andersen’s chart (Andersen & Berre, 1999) is a graphical method of observing cyclic soil response. It allows observing soil response to various stress amplitudes that can lead to liquefaction, excess plastic deformation or stabilizing soil response. The process of obtaining the original chart has...

  20. Obtaining Funding and Support for Undergraduate Research

    Science.gov (United States)

    Dorff, Michael; Narayan, Darren A.

    2013-01-01

    Over the past decade there has been a dramatic increase in undergraduate research activities at colleges and universities nationwide. However, this comes at a time when budgets are being tightened and some institutions do not have the resources to pursue new initiatives. In this article we present some ideas for obtaining funding and support for…