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Sample records for ns implosion time

  1. Radiative Properties of High Wire Number Tungsten Arrays with Implosion Times up to 250 ns

    SciTech Connect

    Beg, F.N.; Coverdale, C.A.; Deeney, C.; Douglas, M.R.; Haines, M.G.; Peterson, D.L.; Roderick, N.F.; Ruiz-Camacho, J.; Spielman, R.B.; Struve, K.W.; Stygar, W.A.

    1999-02-02

    High wire number, 25-mm diameter tungsten wire arrays have been imploded on the 8-MA Saturn generator, operating in a long-pulse mode. By varying the mass load from 710 to 6140 ps/cm, implosion times of 130 to 250 ns have been obtained with implosion velocities of 50 to 25 cn-dys, respectively. These z-pinch implosions produced plasmas with millimeter diameters that radiated 600 to 800 kJ of x-rays, with powers of 20 to 49 TW; the corresponding pulse widths were 19 to 7.5 ns, with risetimes ranging from 6.5 to 4.0 ns. These powers and pulse widths are similar to those achieved with 50 ns implosion times on Saturn. Two-dimensional, radiation- magnetohydrodynamic calculations indicate that the imploding shells in these long implosion time experiments are comparable in width to those in the short pulse cases. This can only be due to lower initial perturbations. A heuristic wire array model suggests that the reduced perturbations, in the long pulse cases, may be due to the individual wire merger occurring well before the acceleration of the shell. The experiments and modeling suggest that 150 to 200 ns implosion time z-pinches could be employed for high-power, x-ray source applications.

  2. First Argon Gas Puff Experiments With 500 ns Implosion Time On Sphinx Driver

    SciTech Connect

    Zucchini, F.; Calamy, H.; Lassalle, F.; Loyen, A.; Maury, P.; Grunenwald, J.; Georges, A.; Morell, A.; Bedoch, J.-P.; Ritter, S.; Combes, P.; Smaniotto, O.; Lample, R.; Coleman, P. L.; Krishnan, M.

    2009-01-21

    Experiments have been performed at the SPHINX driver to study potential of an Argon Gas Puff load designed by AASC. We present here the gas Puff hardware and results of the last shot series.The Argon Gas Puff load used is injected thanks to a 20 cm diameter nozzle. The nozzle has two annuli and a central jet. The pressure and gas type in each of the nozzle plena can be independently adjusted to tailor the initial gaz density distribution. This latter is selected as to obtain an increasing radial density from outer shell towards the pinch axis in order to mitigate the RT instabilities and to increase radiating mass on axis. A flashboard unit produces a high intensity UV source to pre-ionize the Argon gas. Typical dimensions of the load are 200 mm in diameter and 40 mm height. Pressures are adjusted to obtain an implosion time around 550 ns with a peak current of 3.5 MA.With the goal of improving k-shell yield a mass scan of the central jet was performed and implosion time, mainly given by outer and middle plena settings, was kept constant. Tests were also done to reduce the implosion time for two configurations of the central jet. Strong zippering of the radiation production was observed mainly due to the divergence of the central jet over the 40 mm of the load height. Due to that feature k-shell radiation is mainly obtained near cathode. Therefore tests were done to mitigate this effect first by adjusting local pressure of middle and central jet and second by shortening the pinch length.At the end of this series, best shot gave 5 kJ of Ar k-shell yield. PCD detectors showed that k-shell x-ray power was 670 GW with a FWHM of less than 10 ns.

  3. First Argon Gas Puff Experiments With 500 ns Implosion Time On Sphinx Driver

    NASA Astrophysics Data System (ADS)

    Zucchini, F.; Calamy, H.; Lassalle, F.; Loyen, A.; Maury, P.; Grunenwald, J.; Georges, A.; Morell, A.; Bedoch, J.-P.; Ritter, S.; Combes, P.; Smaniotto, O.; Lample, R.; Coleman, P. L.; Krishnan, M.

    2009-01-01

    Experiments have been performed at the SPHINX driver to study potential of an Argon Gas Puff load designed by AASC. We present here the gas Puff hardware and results of the last shot series. The Argon Gas Puff load used is injected thanks to a 20 cm diameter nozzle. The nozzle has two annuli and a central jet. The pressure and gas type in each of the nozzle plena can be independently adjusted to tailor the initial gaz density distribution. This latter is selected as to obtain an increasing radial density from outer shell towards the pinch axis in order to mitigate the RT instabilities and to increase radiating mass on axis. A flashboard unit produces a high intensity UV source to pre-ionize the Argon gas. Typical dimensions of the load are 200 mm in diameter and 40 mm height. Pressures are adjusted to obtain an implosion time around 550 ns with a peak current of 3.5 MA. With the goal of improving k-shell yield a mass scan of the central jet was performed and implosion time, mainly given by outer and middle plena settings, was kept constant. Tests were also done to reduce the implosion time for two configurations of the central jet. Strong zippering of the radiation production was observed mainly due to the divergence of the central jet over the 40 mm of the load height. Due to that feature k-shell radiation is mainly obtained near cathode. Therefore tests were done to mitigate this effect first by adjusting local pressure of middle and central jet and second by shortening the pinch length. At the end of this series, best shot gave 5 kJ of Ar k-shell yield. PCD detectors showed that k-shell x-ray power was 670 GW with a FWHM of less than 10 ns.

  4. Overview of 12-cm-Diameter, Argon Gas-Puff Experiments and Analyses with >200-ns Implosion Times at 3- to 6-MA Peak Currents

    SciTech Connect

    Commisso, R. J.; Apruzese, J. P.; Davis, J.; Murphy, D. P.; Thornhill, J. W.; Velikovich, A. L.; Weber, B. V.; Jackson, S. L.; Mosher, D.; Young, F. C.; Coverdale, C. A.; Jones, B.

    2009-01-21

    This paper reviews the motivation for, results from, and analyses of 12-cm-diameter argon gas-puff experiments carried out over the last four years on three generators at 3.2- to 6.5-MA peak currents, all with implosion times {>=}200 ns. Using the argon K-shell yield as a metric of implosion quality, high-quality implosions are obtained for an appropriate initial radial mass distribution, i.e., a distribution that is peaked on axis. Higher compressed densities and smaller final radii are observed compared to shell-like initial mass distributions. Theory and data suggest that these distributions mitigate the magnetic Rayleigh-Taylor instability. An energy analysis shows that (1) significant electrical energy is directly coupled to the pinch during the K-shell radiation pulse and (2) conversion of radially-directed kinetic energy into thermal energy is not the dominant mechanism responsible for the pinch K-shell radiation.

  5. Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch

    SciTech Connect

    Maury, P.; Calamy, H.; Grunenwald, J.; Lassalle, F.; Zucchini, F.; Loyen, A.; Georges, A.; Morell, A.; Bedoch, J. P.

    2009-01-21

    The Sphinx machine{sup [1]} is a 6 MA, 1 {mu}S driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse{sup [2]}. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during the prepulse phase dramatically changes the ablation phase leading to an improvement of axial homogeneity of both the implosion and the final radiating column. As a consequence, the cathode bubble observed on classical shots is definitively removed. The implosion is then centered and zippering effect is reduced, leading to simultaneous x-ray emission of the whole length. A great reproducibility is obtained. Nested arrays were used before to mitigate the Rayleigh-Taylor instabilities during the implosion phase. Further experiments with pre-pulse technique are described here were inner array was removed. The goal of these experiments was to see if long prepulse could give stable enough implosion with single array and at the same time increase the {eta} parameter by reducing the mass of the load. Experimental results of single wire array loads of typical dimension 5 cm in height with implosion time between 700 and 900 ns and diameter varying between 80 and 140 mm are given. Parameters of the loads were varying in term of radius and number of wires. Comparisons with nested wire array loads are done and trends are proposed. Characteristics of both the implosion and the final radiating column are shown. 2D MHD numerical simulations of single wire array become easier as there is no interaction between outer and inner array anymore. A systematic study was done using injection mass model to benchmark simulation with experiments.

  6. Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch

    NASA Astrophysics Data System (ADS)

    Maury, P.; Calamy, H.; Grunenwald, J.; Lassalle, F.; Zucchini, F.; Loyen, A.; Georges, A.; Morell, A.; Bedoch, J. P.

    2009-01-01

    The Sphinx machine[1] is a 6 MA, 1 μS driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse[2]. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during the prepulse phase dramatically changes the ablation phase leading to an improvement of axial homogeneity of both the implosion and the final radiating column. As a consequence, the cathode bubble observed on classical shots is definitively removed. The implosion is then centered and zippering effect is reduced, leading to simultaneous x-ray emission of the whole length. A great reproducibility is obtained. Nested arrays were used before to mitigate the Rayleigh-Taylor instabilities during the implosion phase. Further experiments with pre-pulse technique are described here were inner array was removed. The goal of these experiments was to see if long prepulse could give stable enough implosion with single array and at the same time increase the η parameter by reducing the mass of the load. Experimental results of single wire array loads of typical dimension 5 cm in height with implosion time between 700 and 900 ns and diameter varying between 80 and 140 mm are given. Parameters of the loads were varying in term of radius and number of wires. Comparisons with nested wire array loads are done and trends are proposed. Characteristics of both the implosion and the final radiating column are shown. 2D MHD numerical simulations of single wire array become easier as there is no interaction between outer and inner array anymore. A systematic study was done using injection mass model to benchmark simulation with experiments.

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

    NASA Astrophysics Data System (ADS)

    Laffite, S.; Bourgade, J. L.; Caillaud, T.; Delettrez, J. A.; Frenje, J. A.; Girard, F.; Glebov, V. Yu.; Joshi, T.; Landoas, O.; Legay, G.; Lemaire, S.; Mancini, R. C.; Marshall, F. J.; Masse, L.; Masson-Laborde, P. E.; Michel, D. T.; Philippe, F.; Reverdin, C.; Seka, W.; Tassin, V.

    2016-01-01

    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%.

  8. Mass and wire number effects of long implosion time Aluminum Z-pinches on Saturn

    NASA Astrophysics Data System (ADS)

    Coverdale, C. A.; Deeney, C.; Lepell, P. D.; Sze, H.; Failor, B.; Coleman, P.; Whitney, K. G.; Thornhill, J. W.; Apruzese, J. P.; Davis, J.; Schneider, R.

    1999-11-01

    Aluminum K-shell emissions from long implosion time Z-pinches have been studied on the 7 MA Saturn accelerator. These experiments, motivated in part by the need to develop Z-pinch sources for the DECADE-Quad pulsed power driver, were designed to investigate the effects of wire number and mass on the Al K-shell radiation. The wire arrays were 40 mm in diameter and the wire number was varied from 32 to 282, holding the mass constant. In a separate scan, the load mass was varied from 400 to 2000 μg/cm, resulting in implosion times of 130 to 180 ns. K-shell yields greater than 60 kJ were measured with pulsewidths as short as 8 ns. These results will be compared with calculations and discussed within the context of K-shell scaling laws. Comparisons will also be made to short implosion time Al experiments performed on Saturn. *This work is supported by the Defense Threat Reduction Agency and the Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94Al85000.

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

    DOE PAGESBeta

    Laffite, S.; Bourgade, J. L.; Caillaud, T.; Delettrez, J A; Frenje, J. A.; Girard, F.; Glebov, V. Yu.; Joshi, Tirtha Raj; Landoas, O.; Legay, G.; et al

    2016-01-14

    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-resolvedmeasurement 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. Inmore » 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 measuredneutron number is about 80% of the prediction. Lastly, for the 2-step 2-ns pulse, we test here that this ratio falls to about 20%.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Experimental Study of Implosion Dynamics of Multi-Shell Z-Pinches at Microsecond Implosion Times

    NASA Astrophysics Data System (ADS)

    Shishlov, Alexander V.; Chaikovsky, Stanislav A.; Fedunin, Anatoly V.; Fursov, Fedor I.; Kokshenev, Vladimir A.; Kurmaev, Nikolai E.; Labetsky, Aleksey Yu.; Oreshkin, Vladimir I.; Rousskikh, Alexander G.; Zhidkova, Natalia A.

    2006-01-01

    A set of experiments has been conducted on the GIT-12 generator (4.7 MA, 1.7 μs) operating at microsecond mode. The experiments were carried out with multi-shell gas puffs. Dynamics of current-carrying plasma was registered by a set of B-dots monitors placed at different radii inside a multi-shell gas puff. The experimental data obtained with the help of B-dots monitors are compared with 0D snow-plow simulations of implosion dynamics and discussed taking into consideration the data from other Z-pinch diagnostics.

  12. [System of ns time-resolved spectroscopy diagnosis and radioprotection].

    PubMed

    Yao, Wei-Bo; Guo, Jian-Ming; Zhang, Yong-min; Tang, Jun-Ping; Cheng, Liang; Xu, Qi-fuo

    2014-06-01

    Cathode plasma of high current electron beam diode is an important research on high power microwave and strong pulsed radio accelerator. It is a reliable method to study cathode plasma by diagnosing the cathode plasma parameters with non-contact spectroscopy measurement system. The present paper introduced the work principle, system composition and performance of the nanosecond (ns) time-resolved spectroscopy diagnosis system. Furthermore, it introduced the implementing method and the temporal relation of lower jitter synchronous trigger system. Simultaneously, the authors designed electromagnetic and radio shield room to protect the diagnosis system due to the high electromagnetic and high X-ray and γ-ray radiation, which seriously interferes with the system. Time-resolved spectroscopy experiment on brass (H62) cathode shows that, the element and matter composition of cathode plasma is clearly increase with the increase in the diode pulsed voltage and current magnitude. The spectroscopy diagnosis system could be of up to 10 ns time resolve capability. It's least is 2 ns. Synchronous trigger system's jitter is less than 4 ns. The spectroscopy diagnosis system will open a new way to study the cathode emission mechanism in depth. PMID:25358142

  13. X-ray emission current scaling experiments for compact single-tungsten-wire arrays at 80-nanosecond implosion times.

    PubMed

    Mazarakis, Michael G; Cuneo, Michael E; Stygar, William A; Harjes, Henry C; Sinars, Daniel B; Jones, Brent M; Deeney, Christopher; Waisman, Eduardo M; Nash, Thomas J; Struve, Kenneth W; McDaniel, Dillon H

    2009-01-01

    We report the results of a series of current scaling experiments with the Z accelerator for the compact, single, 20-mm diameter, 10-mm long, tungsten-wire arrays employed for the double-ended hohlraum ICF concept [M. E. Cuneo, Plasma Phys. Controlled Fusion 48, R1 (2006)]. We measured the z -pinch peak radiated x-ray power and total radiated x-ray energy as a function of the peak current, at a constant implosion time tau_{imp}=80ns . Previous x-ray emission current scaling for these compact arrays was obtained at tau_{imp}=95ns in the work of Stygar [Phys. Rev. E 69, 046403 (2004)]. In the present study we utilized lighter single-tungsten-wire arrays. For all the measurements, the load hardware dimensions, materials, and array wire number (N=300) were kept constant and were the same as the previous study. We also kept the normalized load current spatial and temporal profiles the same for all experiments reported in this work. Two different currents, 11.2+/-0.2MA and 17.0+/-0.3MA , were driven through the wire arrays. The average peak x-ray power for these compact wire arrays increased by 26%+/-7%to158+/-26TW at 17+/-0.3MA from the 125+/-24TW obtained at a peak current of 18.8+/-0.5MA with tau_{imp}=95ns . The higher peak power of the faster implosions may possibly be attributed to a higher implosion velocity, which in turn improves the implosion stability, and/or to shorter wire ablation times, which may lead to a decrease in trailing mass and trailing current. Our results show that the scaling of the radiated x-ray peak power and total radiated x-ray energy scaling with peak drive current to be closer to quadratic than the results of Stygar We find that the x-ray peak radiated power is P_{r} proportional, variantI;{1.57+/-0.20} and the total x-ray radiated energy E_{r} proportional, variantI;{1.9+/-0.24} . We also find that the current scaling exponent of the power is sensitive to the inclusion of a single data point with a peak power at least 1.9sigma below the

  14. The effects of early time laser drive on hydrodynamic instability growth in National Ignition Facility implosions

    SciTech Connect

    Peterson, J. L.; Clark, D. S.; Suter, L. J.; Masse, L. P.

    2014-09-15

    Defects on inertial confinement fusion capsule surfaces can seed hydrodynamic instability growth and adversely affect capsule performance. The dynamics of shocks launched during the early period of x-ray driven National Ignition Facility (NIF) implosions determine whether perturbations will grow inward or outward at peak implosion velocity and final compression. In particular, the strength of the first shock, launched at the beginning of the laser pulse, plays an important role in determining Richtmyer-Meshkov (RM) oscillations on the ablation front. These surface oscillations can couple to the capsule interior through subsequent shocks before experiencing Rayleigh-Taylor (RT) growth. We compare radiation hydrodynamic simulations of NIF implosions to analytic theories of the ablative RM and RT instabilities to illustrate how early time laser strength can alter peak velocity growth. We develop a model that couples the RM and RT implosion phases and captures key features of full simulations. We also show how three key parameters can control the modal demarcation between outward and inward growth.

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

    SciTech Connect

    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.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.

    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.

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

    NASA Astrophysics Data System (ADS)

    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.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

    2014-02-01

    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.

  17. Characterization of direct-drive-implosion core conditions on OMEGA with time-resolved Ar K-shell spectroscopy

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; Delettrez, J. A.; Epstein, R.; Jaanimagi, P. A.; Yaakobi, B.; Smalyuk, V. A.; Marshall, F. J.; Meyerhofer, D. D.; Seka, W.; Haynes, D. A.; Golovkin, I. E.; Hooper, C. F.

    2002-04-01

    Direct-drive-implosion core conditions have been characterized on the 60-beam OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system with time-resolved Ar K-shell spectroscopy. Plastic shells with an Ar-doped deuterium fill gas were driven with a 23 kJ, 1 ns square laser pulse smoothed with 1 THz smoothing by spectral dispersion (SSD) and polarization smoothing (PS) using birefringent wedges. The targets are predicted to have a convergence ratio of ˜15. The emissivity-averaged core electron temperature (Te) and density (ne) were inferred from the measured time-dependent Ar K-shell spectral line shapes. As the imploding shell decelerates the observed Te and ne increase to 2.0 (±0.2) keV and 2.5 (±0.5)×1024cm-3 at peak neutron production, which is assumed to occur at the time of the peak emissivity-averaged Te. At peak compression the ne increases to 3.1 (±0.6)×1024cm-3 and the Te decreases to 1.7 (±0.17) keV. The observed core conditions are close to those predicted by a one-dimensional hydrodynamics code.

  18. Early stage of implosion in inertial confinement fusion: Shock timing and perturbation evolution

    NASA Astrophysics Data System (ADS)

    Goncharov, V. N.; Gotchev, O. V.; Vianello, E.; Boehly, T. R.; Knauer, J. P.; McKenty, P. W.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Skupsky, S.; Smalyuk, V. A.; Betti, R.; McCrory, R. L.; Meyerhofer, D. D.; Cherfils-Clérouin, C.

    2006-01-01

    Excessive increase in the shell entropy and degradation from spherical symmetry in inertial confinement fusion implosions limit shell compression and could impede ignition. The entropy is controlled by accurately timing shock waves launched into the shell at an early stage of an implosion. The seeding of the Rayleigh-Taylor instability, the main source of the asymmetry growth, is also set at early times during the shock transit across the shell. In this paper we model the shock timing and early perturbation growth of directly driven targets measured on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. By analyzing the distortion evolution, it is shown that one of the main parameters characterizing the growth is the size of the conduction zone Dc, defined as a distance between the ablation front and the laser deposition region. Modes with kDc>1 are stable and experience oscillatory behavior [V. N. Goncharov, Phys. Rev. Lett. 82, 2091 (1999)]. The model shows that the main stabilizing mechanism is the dynamic overpressure due to modulations in the blow-off velocity inside the conduction zone. The long wavelengths with kDc<1 experience growth because of coupled Richtmyer-Meshkov-like and Landau-Darrieus instabilities [L. D. Landau and E. M. Lifshitz, Fluid Mechanics (Pergamon, New York, 1982)]. To match the simulation results with both the shock timing and perturbation growth measurements a new nonlocal thermal transport model is developed and used in hydrocodes.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Time-resolved characterization and energy balance analysis of implosion core in shock-ignition experiments at OMEGA

    SciTech Connect

    Florido, R. Mancini, R. C.; Nagayama, T.; Tommasini, R.; Delettrez, J. A.; Regan, S. P.

    2014-10-15

    Time-resolved temperature and density conditions in the core of shock-ignition implosions have been determined for the first time. The diagnostic method relies on the observation, with a streaked crystal spectrometer, of the signature of an Ar tracer added to the deuterium gas fill. The data analysis confirms the importance of the shell attenuation effect previously noted on time-integrated spectroscopic measurements of thick-wall targets [R. Florido et al., Phys. Rev. E 83, 066408 (2011)]. This effect must be taken into account in order to obtain reliable results. The extracted temperature and density time-histories are representative of the state of the core during the implosion deceleration and burning phases. As a consequence of the ignitor shock launched by the sharp intensity spike at the end of the laser pulse, observed average core electron temperature and mass density reach T ∼ 1100 eV and ρ ∼ 2 g/cm{sup 3}; then temperature drops to T ∼ 920 eV while density rises to ρ ∼ 3.4 g/cm{sup 3} about the time of peak compression. Compared to 1D hydrodynamic simulations, the experiment shows similar maximum temperatures and smaller densities. Simulations do not reproduce all observations. Differences are noted in the heating dynamics driven by the ignitor shock and the optical depth time-history of the compressed shell. Time-histories of core conditions extracted from spectroscopy show that the implosion can be interpreted as a two-stage polytropic process. Furthermore, an energy balance analysis of implosion core suggests an increase in total energy greater than what 1D hydrodynamic simulations predict. This new methodology can be implemented in other ICF experiments to look into implosion dynamics and help to understand the underlying physics.

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

    SciTech Connect

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

    2009-01-21

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D{sup 3}He and DT implosions at the NIF

    SciTech Connect

    Rinderknecht, H. G.; Johnson, M. Gatu; Zylstra, A. B.; Sinenian, N.; Rosenberg, M. J.; Frenje, J. A.; Waugh, C. J.; Li, C. K.; Seguin, 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.; and others

    2012-10-15

    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 {rho}R 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{sup 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{sup 3}He-filled surrogate implosions using D{sup 3}He protons and DD-neutrons, respectively.

  6. Near-vacuum hohlraums for driving fusion implosions with high density carbon ablators

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, Laura

    2014-10-01

    Achieving ignition requires reaching fast implosion velocities, which highlights the need for a highly efficient hohlraum to drive indirect-drive inertial confinement fusion implosions. Gas-filled hohlraums are typically utilized due to the pulse length (15-20 ns) needed to drive plastic (CH) capsules. With the recent use of 3× denser high-density carbon (HDC) capsules, ignition pulses can be less than 10 ns in duration, providing the opportunity to utilize near-vacuum hohlraums (NVH) to drive ignition-relevant implosions on the National Ignition Facility (NIF) with minimal laser-plasma instabilities which complicate standard gas-filled hohlraums. Initial NVH implosions on the NIF have demonstrated coupling efficiency significantly higher than observed in gas-filled hohlraums - backscatter losses less than 2% and virtually no suprathermal electron generation. A major design challenge for the NVH is symmetry control. Without tamping gas, the hohlraum wall quickly expands filling the volume with gold plasma. However, results to-date indicate that the inner-cone beams propagate freely to the hohlraum wall for at least 6.5 ns. With minimal predicted cross-beam power transfer, this propagation enables symmetry control via dynamic beam phasing - time-dependent direct adjustment of the inner- and outer-cone laser pulses. A series of experiments with an HDC ablator and NVH culminated in a 6 ns, 1.2 MJ cryogenic DT layered implosion yielding 1.8 × 1015 neutrons--significantly higher yield than any CH implosion at comparable energy. This implosion reached an ignition-relevant velocity -350 km/s - with no observed ablator mix in the hot spot. Recent experiments have explored two-shock designs in a larger, 6.72 mm hohlraum, and upcoming experiments will incrementally extend the pulse duration toward a 9 ns long, three-shock ignition design. Prepared by LLNL under Contract DE-AC52-07NA27344.

  7. Early time implosion symmetry from two-axis shock-timing measurements on indirect drive NIF experiments

    SciTech Connect

    Moody, J. D. Robey, H. F.; Celliers, P. M.; Munro, D. H.; Barker, D. A.; Baker, K. L.; Döppner, T.; Hash, N. L.; Berzak Hopkins, L.; LaFortune, K.; Landen, O. L.; LePape, S.; MacGowan, B. J.; Ralph, J. E.; Ross, J. S.; Widmayer, C.; Nikroo, A.; Giraldez, E.; Boehly, T.

    2014-09-15

    An innovative technique has been developed and used to measure the shock propagation speed along two orthogonal axes in an inertial confinement fusion indirect drive implosion target. This development builds on an existing target and diagnostic platform for measuring the shock propagation along a single axis. A 0.4 mm square aluminum mirror is installed in the ablator capsule which adds a second orthogonal view of the x-ray-driven shock speeds. The new technique adds capability for symmetry control along two directions of the shocks launched in the ablator by the laser-generated hohlraum x-ray flux. Laser power adjustments in four different azimuthal cones based on the results of this measurement can reduce time-dependent symmetry swings during the implosion. Analysis of a large data set provides experimental sensitivities of the shock parameters to the overall laser delivery and in some cases shows the effects of laser asymmetries on the pole and equator shock measurements.

  8. Implosion dynamics of wire-array z-pinches on the COBRA accelerator

    NASA Astrophysics Data System (ADS)

    McBride, R. D.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A.; Douglass, J. D.; Greenly, J. B.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Blanchard, T.; Wilhelm, H.; Hammer, D. A.; Kusse, B. R.

    2007-11-01

    Experimental results characterizing wire-array z-pinch implosion dynamics on the 1-MA, 100-ns rise time COBRA pulsed power generator are presented. Diagnostics fielded include an optical streak camera, a time-gated XUV framing camera, a laser shadowgraph system, filtered time-integrated pinhole cameras, a focusing x-ray spectrometer with spatial resolution (FSSR), a load voltage monitor, a faraday cup, a bolometer, silicon diodes and diamond photoconducting detectors (PCDs). The load geometries investigated in this set of experiments include cylindrical arrays ranging from 6 to 16 mm in diameter, and consisting of 8, 16, or 32 wires of either aluminum (Al) or tungsten (W). The data produced by the entire suite of diagnostics are analyzed and presented to provide an overall picture of implosion dynamics and timing on COBRA. In particular, data fitting to various implosion trajectory models, as well as x-ray pulse shape dependencies on various loads and implosion characteristics are presented and discussed.

  9. Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

    NASA Astrophysics Data System (ADS)

    Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J. P.; Chittenden, J. P.; Lebedev, S. V.; Jennings, C. A.; Bland, S. N.

    2006-01-01

    Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1μs rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-θ simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

  10. Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

    SciTech Connect

    Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J.P.; Chittenden, J.P.; Lebedev, S.V.; Jennings, C.A.; Bland, S.N.

    2006-01-05

    Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1{mu}s rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-{theta} simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

  11. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch.

    PubMed

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source. PMID:26521006

  12. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch

    NASA Astrophysics Data System (ADS)

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source.

  13. Tungsten Z-Pinch Long Implosions on the Saturn Generator

    SciTech Connect

    DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; HAINES,M.G.

    1999-11-05

    Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (>20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment.

  14. Measurements of Magneto-Rayleigh-Taylor Instability Growth during the Implosion of Initially Solid Al Tubes Driven by the 20-MA, 100-ns Z Facility

    SciTech Connect

    Sinars, D. B.; Slutz, S. A.; Herrmann, M. C.; McBride, R. D.; Cuneo, M. E.; Peterson, K. J.; Vesey, R. A.; Nakhleh, C.; Tomlinson, K.; Edens, A. D.; Lopez, M. R.; Smith, I. C.; Shores, J.; Bigman, V.; Bennett, G. R.; Atherton, B. W.; Savage, M.; Stygar, W. A.; Leifeste, G. T.; Porter, J. L.

    2010-10-29

    The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast ({approx}100 ns) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of 25-400 {mu}m were used to seed the instability. Radiographs with 15 {mu}m resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to 50 {mu}m wavelengths.

  15. Wellbottom fluid implosion treatment system

    SciTech Connect

    Brieger, Emmet F.

    2001-01-01

    A system for inducing implosion shock forces on perforation traversing earth formations with fluid pressure where an implosion tool is selected relative to a shut in well pressure and a tubing pressure to have a large and small area piston relationship in a well tool so that at a predetermined tubing pressure the pistons move a sufficient distance to open an implosion valve which permits a sudden release of well fluid pressure into the tubing string and produces an implosion force on the perforations. A pressure gauge on the well tool records tubing pressure and well pressure as a function of time.

  16. Analysis of time-resolved argon line spectra from OMEGA direct-drive implosions

    SciTech Connect

    Florido, R.; Nagayama, T.; Mancini, R. C.; Tommasini, R.; Delettrez, J. A.; Regan, S. P.; Smalyuk, V. A.; Rodriguez, R.; Gil, J. M.

    2008-10-15

    We discuss the observation and data analysis of argon K-shell line spectra from argon-doped deuterium-filled OMEGA direct-drive implosion cores based on data recorded with two streaked crystal spectrometers. The targets were 870 {mu}m in diameter, 27 {mu}m wall thickness plastic shells filled with 20 atm of deuterium gas, and a tracer amount of argon for diagnostic purposes. The argon K-shell line spectrum is primarily emitted at the collapse of the implosion and its analysis provides a spectroscopic diagnostic of the core implosion conditions. The observed spectra includes the He{alpha}, Ly{alpha}, He{beta}, He{gamma}, Ly{beta}, and Ly{gamma} line emissions and their associated He- and Li-like satellites thus covering a broad photon energy range from 3100 to 4200 eV with a spectral resolution power of approximately 500. The data analysis relies on detailed atomic and spectral models that take into account nonequilibrium collisional-radiative atomic kinetics, Stark-broadened line shapes, and radiation transport calculations.

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

    SciTech Connect

    Douglas, M.R.; Deeney, C.; Spielman, R.B.; Roderick, N.; Haines, M.G.

    1999-07-01

    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.

  18. Diagnostics for Z-pinch implosion experiments on PTS

    SciTech Connect

    Ren, X. D. Huang, X. B. Zhou, S. T. Zhang, S. Q. Dan, J. K. Li, J. Cai, H. C. Wang, K. L. Ouyang, K. Xu, Q. Duan, S. C. Chen, G. H. Wang, M. Feng, S. P. Yang, L. B. Xie, W. P. Deng, J. J.

    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.

  19. Tuning indirect-drive implosions using cone power balance

    NASA Astrophysics Data System (ADS)

    Kyrala, G. A.; Seifter, A.; Kline, J. L.; Goldman, S. R.; Batha, S. H.; Hoffman, N. M.

    2011-07-01

    We demonstrate indirect-drive implosion symmetry tuning in a vacuum hohlraum 6.6 mm in length and 3.56 mm in diameter with a CH capsule 6.38 μm in thickness and 1414 μm in diameter, scaled roughly 0.7 × from a National ignition facility (NIF) [E. Moses and C. R. Wuest, Fusion Sci. Technol. 47, 314 (2005)] The hohlraums have radiation drives of 117 ± 4 eV relevant to conditions for the first ˜1 ns of ignition experiments. By varying the relative ratio of the energy between inner and outer beam cones illuminating the hohlraum at OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. the shape of the x-ray self-emission, and hence the shape of the emitting object, can be tuned from prolate to oblate. The second-order Legendre coefficient, used to characterize the shape, changes from a negative to a positive value at the time of peak x-ray emission during the implosion through the variation of the cone power balance. With the appropriate selection of the cone power balance, the implosion can be tuned to produce a spherical implosion. Using capsules with thicker walls, this technique can be extended to measure the drive symmetry at later times as the length of the drive pulse is increased [N. M. Hoffman et al., J. Phys.: Conf. Ser. 112, 022075 (2008); N. M. Hoffman et al., Phys. Plasmas 3, 2022 (1996)].

  20. Proton Radiography of a Laser-Driven Implosion

    SciTech Connect

    Mackinnon, A. J.; Patel, P. K.; Hatchett, S. P.; Hey, D.; Hicks, D. G.; Key, M. H.; Phillips, T. W.; Snavely, R. A.; Town, R. P. J.; Borghesi, M.; Kar, S.; Romagnani, L.; Clarke, R. C.; Freeman, R. R.; Habara, H.; Lancaster, K.; Neely, D.; Norreys, P. A.; Notley, M. M.; King, J. A.

    2006-07-28

    Protons accelerated by a picosecond laser pulse have been used to radiograph a 500 {mu}m diameter capsule, imploded with 300 J of laser light in 6 symmetrically incident beams of wavelength 1.054 {mu}m and pulse length 1 ns. Point projection proton backlighting was used to characterize the density gradients at discrete times through the implosion. Asymmetries were diagnosed both during the early and stagnation stages of the implosion. Comparison with analytic scattering theory and simple Monte Carlo simulations were consistent with a 3{+-}1 g/cm{sup 3} core with diameter 85{+-}10 {mu}m. Scaling simulations show that protons >50 MeV are required to diagnose asymmetry in ignition scale conditions.

  1. Implosion Dynamics in Conical Wire Array Z-pinches

    SciTech Connect

    Ampleford, D.J.; Lebedev, S.V.; Chittenden, J.P.; Bland, S.N.; Bott, S.C.; Hall, G.N.; Palmer, J.B.A.; Rapley, J.; Kantsyrev, V.L.; Safronova, A.S.; Ivanov, V.V.; Fedin, D.A.; Laca, P.J.; Sotnikov, V.I.; Yilmaz, F.; Ouart, N.; Nalajala, V.; Shrestha, I.; Pokala, S.; Jones, B.

    2006-01-05

    We present initial results from imploding conical wire array experiments performed on both the MAGPIE generator (1MA, 240ns) at Imperial College London and the Nevada Terawatt Facility's Zebra generator (1MA, 100ns) at University of Nevada, Reno. This paper will discuss the implosion dynamics of conical wire arrays, including initial implosion of the cathode end of the array and the formation of a magnetic bubble.

  2. Broadband time-domain absorption spectroscopy with a ns-pulse supercontinuum source.

    PubMed

    Sych, Yaroslav; Engelbrecht, Rainer; Schmauss, Bernhard; Kozlov, Dimitrii; Seeger, Thomas; Leipertz, Alfred

    2010-10-25

    A Q-switched laser based system for broadband absorption spectroscopy in the range of 1390-1740 nm (7200-5750 cm(-1)) has been developed and tested. In the spectrometer the 1064 nm light of a 25 kHz repetition-rate micro-chip Nd:YAG laser is directed into a photonic crystal fiber to produce a short (about 2 ns) pulse of radiation in a wide spectral range. This radiation is passed through a 25 km long dispersive single-mode fiber in order to spread the respective wavelengths over a time interval of about 140 ns at the fiber output. This fast swept-wavelength light source allows to record gas absorption spectra by temporally-resolved detection of the transmitted light power. The realized spectral resolution is about 2 cm(-1). Examples of spectra recorded in a cell with CO(2):CH(4):N(2) gas mixtures are presented. An algorithm employed for the evaluation of molar concentrations of different species from the spectra with non-overlapping absorption bands of mixture components is described. The uncertainties of the concentration values retrieved at different acquisition times due to the required averaging are evaluated. As an example, spectra with a signal-to-noise ratio large enough to provide species concentrations with a relative error of 5% can be obtained in real time at a millisecond time scale. Potentials and limitations of this technique are discussed. PMID:21164614

  3. A 16K-bit static IIL RAM with 25-ns access time

    NASA Astrophysics Data System (ADS)

    Inabe, Y.; Hayashi, T.; Kawarada, K.; Miwa, H.; Ogiue, K.

    1982-04-01

    A 16,384 x 1-bit RAM with 25-ns access time, 600-mW power dissipation, and 33 sq mm chip size has been developed. Excellent speed-power performance with high packing density has been achieved by an oxide isolation technology in conjunction with novel ECL circuit techniques and IIL flip-flop memory cells, 980 sq microns (35 x 28 microns) in cell size. Development results have shown that IIL flip-flop memory cell is a trump card for assuring achievement of a high-performance large-capacity bipolar RAM, in the above 16K-bit/chip area.

  4. Implosion dynamics and radiative characteristics of a high yield structured gas puff load

    SciTech Connect

    Levine, J. S.; Banister, J. W.; Failor, B. H.; Qi, N.; Sze, H. M.; Velikovich, A. L.; Commisso, R. J.; Davis, J.; Lojewski, D.

    2006-08-15

    A large diameter gas puff nozzle, designed to produce a radial mass profile with a substantial fraction of the injected mass on the axis, has demonstrated an increase in K shell yield by nearly a factor of 2, to 21 kJ, in an argon Z pinch at 3.5 MA peak current and 205 ns implosion time [H. Sze, J. Banister, B. H. Failor, J. S. Levine, N. Qi, A. L. Velikovich, J. Davis, D. Lojewski, and P. Sincerny, Phys. Rev. Lett. 95, 105001 (2005)] and 80 kJ at 6 MA and 227 ns implosion time. The initial gas distribution produced by this nozzle has been determined and related to measured plasma dynamics during the implosion run-in phase. The role of two gas shells and the center jet are elucidated by the inclusion of a tracer element sequentially into each of the three independent plenums and by evacuating each plenum. The implosion dynamics and radiative characteristics of the Z pinches are presented.

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

    SciTech Connect

    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.

  6. KM3NeT Neutrino Telescope 1-ns Resolution Time To Digital Converters

    NASA Astrophysics Data System (ADS)

    Calvo, David; Real, Diego

    2016-04-01

    The KM3NeT collaboration aims the construction of a multi-km3 high-energy neutrino telescope in the Mediterranean sea consisting of thousands of glass spheres, each of them containing 31 photomultiplier of small photocathode area. The main digitization system is composed by 31 Time to Digital Converter channels with 1-ns resolution embedded in a Field Programmable Gate Array. An architecture with low resource occupancy has been chosen allowing the implementation of other instrumentation, communication and synchronization systems on the same device. The 4-oversampling technique with two high frequency clocks working in opposed phases has been used together with an asymmetric FIFO memory. In the present article the architecture and the first results obtained with the Time to Digital Converters are presented.

  7. A novel particle Time Of Flight (pTOF) diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF

    SciTech Connect

    Mackinnon, A; Rinderknecht, H G; Johnson, M G; Zylstra, A B; Sinenian, N; Rosenbergh, M J; Frenje, J A; Waugh, C J; Li, C K; Seguin, F H; Petrasso, R; Rygg, J R; Kline, J; Doeppner, T; Park, H S; Landen, O; Lepape, S; Meezan, N; Kilkenny, J; Glebov, V Y; Sangster, T; Stoeckl, C; Olson, R

    2012-05-02

    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 {rho}R 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{sup 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{sup 3}He-filled surrogate implosions using D{sup 3}He protons and DD-neutrons, respectively.

  8. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    SciTech Connect

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-19

    In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As a result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.

  9. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    DOE PAGESBeta

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-19

    In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As amore » result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.« less

  10. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    NASA Astrophysics Data System (ADS)

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-01

    In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ˜600 kA with ˜200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.

  11. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents.

    PubMed

    Yager-Elorriaga, D A; Steiner, A M; Patel, S G; Jordan, N M; Lau, Y Y; Gilgenbach, R M

    2015-11-01

    In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ∼600 kA with ∼200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines. PMID:26628134

  12. 1 ns time to digital converters for the KM3NeT data readout system

    SciTech Connect

    Calvo, David [IFIC, Instituto de Física Corpuscular, CSIC- Universidad de Valencia, C Collaboration: KM3NeT Collaboration

    2014-11-18

    The KM3NeT collaboration aims at the construction of a multi-km3 high-energy neutrino telescope in the Mediterranean Sea consisting of thousands of glass spheres (nodes), each of them containing 31 photomultiplier (PMT) of small photocathode area. The readout and data acquisition system of KM3NeT has to collect, treat and send to shore, in an economic way, the enormous amount of data produced by the photomultipliers. For this purpose, 31 high-resolution time-interval measuring channels are implemented on the Field-Programmable Gate Arrays (FPGA) based on Time to Digital Converter (TDC). TDC are very common devices in particles physics experiments. Architectures with low resources occupancy are desirable allowing the implementation of other instrumentation, communication and synchronization systems on the same device. The required resolution to measure both, time of flight and timestamp must be 1 ns. A 4-Oversampling technique with two high frequency clocks is used to achieve this resolution. The proposed TDC firmware is developed using very few resources in Xilinx Kintex-7.

  13. Wideband fluorescence-based thermometry by neural network recognition: Photothermal application with 10 ns time resolution

    NASA Astrophysics Data System (ADS)

    Liu, Liwang; Zhong, Kuo; Munro, Troy; Alvarado, Salvador; Côte, Renaud; Creten, Sebastiaan; Fron, Eduard; Ban, Heng; Van der Auweraer, Mark; Roozen, N. B.; Matsuda, Osamu; Glorieux, Christ

    2015-11-01

    Neural network recognition of features of the fluorescence spectrum of a thermosensitive probe is exploited in order to achieve fluorescence-based thermometry with an accuracy of 200 mK with 100 MHz bandwidth, and with high robustness against fluctuations of the probe laser intensity used. The concept is implemented on a rhodamine B dyed mixture of copper chloride and glycerol, and the temperature dependent fluorescence is investigated in the temperature range between 234 K and 311 K. The spatial dependence of the calibrated amplitude and phase of photothermally induced temperature oscillations along the axis of the excitation laser are determined at different modulation frequencies. The spatial and frequency dependence of the extracted temperature signals is well fitted by a 1D multi-layer thermal diffusion model. In a time domain implementation of the approach, the gradual temperature rise due to the accumulation of the DC component of the heat flux supplied by repetitive laser pulses as well the immediate transient temperature evolution after each single pulse is extracted from acquired temporal sequences of fluorescence spectra induced by a CW green laser. A stroboscopic implementation of fluorescence thermometry, using a pulsed fluorescence evoking probe laser, is shown to achieve remote detection of temperature changes with a time resolution of 10 ns.

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

    SciTech Connect

    Serrano, Jason Dimitri; Chuvatin, Alexander S.; Jones, M. C.; Vesey, Roger Alan; Waisman, Eduardo M.; Ivanov, V. V.; Esaulov, Andrey A.; Ampleford, David J.; Cuneo, Michael Edward; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Rudakov, L. I.; Jones, Brent Manley; Safronova, Alla S.; 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

  15. Bounce-free spherical hydrodynamic implosion

    SciTech Connect

    Kagan, Grigory; Tang Xianzhu; Hsu, Scott C.; Awe, Thomas J.

    2011-12-15

    In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot core plasma does not expand against the imploding flow. Such an implosion scheme has the advantage of improving the dwell time of the burning fuel, resulting in a higher fusion burn-up fraction. The existence of bounce-free spherical implosions is demonstrated by explicitly constructing a family of self-similar solutions to the spherically symmetric ideal hydrodynamic equations. When applied to a specific example of plasma liner driven magneto-inertial fusion, the bounce-free solution is found to produce at least a factor of four improvement in dwell time and fusion energy gain.

  16. The effect of laser pulse shape variations on the adiabat of NIF capsule implosions

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; MacGowan, B. J.; Landen, O. L.; LaFortune, K. N.; Widmayer, C.; Celliers, P. M.; Moody, J. D.; Ross, J. S.; Ralph, J.; LePape, S.; Berzak Hopkins, L. F.; Spears, B. K.; Haan, S. W.; Clark, D.; Lindl, J. D.; Edwards, M. J.

    2013-05-01

    Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shape (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (˜0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.

  17. The effect of laser pulse shape variations on the adiabat of NIF capsule implosions

    SciTech Connect

    Robey, H. F.; MacGowan, B. J.; Landen, O. L.; LaFortune, K. N.; Widmayer, C.; Celliers, P. M.; Moody, J. D.; Ross, J. S.; Ralph, J.; LePape, S.; Berzak Hopkins, L. F.; Spears, B. K.; Haan, S. W.; Clark, D.; Lindl, J. D.; Edwards, M. J.

    2013-05-15

    Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shape (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (∼0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.

  18. Plasma viscosity in spherical ICF implosion simulations

    NASA Astrophysics Data System (ADS)

    Vold, E.; Joglekar, A.; Ortega, M.; Moll, R.; Fenn, D.; Molvig, K.

    2016-05-01

    Inertial confinement fusion (ICF) hydrodynamic codes often ignore the effects of viscosity though recent research indicates plasma viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. 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, is used to study differences between ICF implosions with and without plasma viscosity and to examine the role of artificial viscosity in a Lagrangian implosion simulation. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, fuel compression, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and this study suggests that artificial viscosity may provide an unphysical stability in implosion simulations.

  19. Long-Implosion-Time Z-pinch Experiments with Deuterium Gas-Puffs on the GIT-12 Generator

    NASA Astrophysics Data System (ADS)

    Klir, D.; Kubes, P.; Rezac, K.; Cikhardt, J.; Kravarik, J.; Shishlov, A.; Labetsky, A.; Fursov, F.; Kokshenev, V.; Kovalchuk, B.; Kurmaev, N.; Ratakhin, N.

    2012-10-01

    Experiments with deuterium triple shell gas-puffs have been carried out on the GIT-12 generator at the IHCE in Tomsk. 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 spectra was studied. The linear mass density of deuterium varied between 50 and 270 μg/cm. Gas puffs imploded onto the axis before the peak of a generator current at 700-1100 ns. The first neutron peak occurred during the stagnation. Most of the neutrons were emitted during the second neutron pulse after the development of instabilities. In lower mass gas puffs, neutron energies of up to 4.4 MeV gave the evidence of 1 MeV deuterons. The peak neutron yield from D(d,n)^3He reactions reached 3x10^11 on a current level of 2.5 MA. Secondary DT neutrons were measured by BDS-10000 bubble detectors. An average neutron yield ratio Y>10 MeV/Y2.5 MeV exceeded (6±3)x10-4. Ne-Ne-D2 and Ne-D2-D2 gas puffs produced 3 times lower neutron yields but the first neutron pulse during the stagnation was nearly the same as with D2-D2-D2 gas puffs.

  20. Investigation of Electric and Self-Generated Magnetic Fields in Implosion Experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Igumenshchev, I. V.; Nilson, P. M.; Goncharov, V. N.; Li, C. K.; Zylstra, A. B.; Petrasso, R. D.

    2013-10-01

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA laser were investigated using proton radiography. The experiments use plastic-shell targets with various surface defects (glue spot, wire, and stalk mount) to seed perturbations and generate localized electromagnetic fields at the ablation surface and in the plasma corona surrounding the targets. Proton radiographs show features from these perturbations and quasi-spherical multiple shell structures around the capsules at earlier times of implosions (up to ~700 ps for a 1-ns laser pulse) indicating the development of the fields. Two-dimensional magnetohydrodynamic simulations of these experiments predict the growth of magnetic fields up to several MG. The simulated distributions of electromagnetic fields were used to produce proton images, which show good agreement with experimental radiographs. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Target Performance in Pd-Overcoated Spherical OMEGA Implosions

    NASA Astrophysics Data System (ADS)

    Radha, P. B.; Stoeckl, C.; Fiksel, G.; Goncharov, V. N.; Hu, S. X.; Knauer, J. P.; Michel, D. T.; Sangster, T. C.; Seka, W.

    2014-10-01

    Improved yields in implosions of plastic (CH) shell targets overcoated with a thin (approximately a few hundred angstroms) of Pd have been measured in OMEGA implosions. Implosions with triple-picket pulses and room-temperature, Pd-overcoated CH shells, where the in-flight aspect ratio (IFAR) has been varied between 19 and 28, are studied on the OMEGA laser. Marginal improvement in yield is found for the lower-IFAR implosions, whereas the higher-IFAR, ignition-relevant implosions show no improvement. Simulations of scattered light, trajectories, bang-time, areal densities, and time-resolved x-ray spectra are compared to experiments. Progress in understanding the role of imprint in target performance in OMEGA implosions is presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  2. Note: Design of a full photon-timing recorder down to 1-ns resolution for fluorescence fluctuation measurements

    NASA Astrophysics Data System (ADS)

    Nishimura, Goro

    2015-10-01

    A photon timing recorder was realized in a field programmable gate array to capture all timing data of photons on multiple channels with down to a 1-ns resolution and to transfer all data to a host computer in real-time through universal serial bus with more than 10 M events/s transfer rate. The main concept is that photon time series can be regarded as a serial communication data stream. This recorder was successfully applied for simultaneous measurements of fluorescence fluctuation and lifetime of near-infrared dyes in solution. This design is not only limited to the fluorescence fluctuation measurement but also applicable to any kind of photon counting experiments in a nanosecond time range because of the simple and easily modifiable design.

  3. Note: Design of a full photon-timing recorder down to 1-ns resolution for fluorescence fluctuation measurements

    SciTech Connect

    Nishimura, Goro

    2015-10-15

    A photon timing recorder was realized in a field programmable gate array to capture all timing data of photons on multiple channels with down to a 1-ns resolution and to transfer all data to a host computer in real-time through universal serial bus with more than 10 M events/s transfer rate. The main concept is that photon time series can be regarded as a serial communication data stream. This recorder was successfully applied for simultaneous measurements of fluorescence fluctuation and lifetime of near-infrared dyes in solution. This design is not only limited to the fluorescence fluctuation measurement but also applicable to any kind of photon counting experiments in a nanosecond time range because of the simple and easily modifiable design.

  4. Conditional Inducible Triple-Transgenic Mouse Model for Rapid Real-Time Detection of HCV NS3/4A Protease Activity

    PubMed Central

    Yang, Jing; Zhao, Haiwei; Qiao, Qinghua; Han, Peijun; Xu, Zhikai; Yin, Wen

    2016-01-01

    Hepatitis C virus (HCV) frequently establishes persistent infections that can develop into severe liver disease. The HCV NS3/4A serine protease is not only essential for viral replication but also cleaves multiple cellular targets that block downstream interferon activation. Therefore, NS3/4A is an ideal target for the development of anti-HCV drugs and inhibitors. In the current study, we generated a novel NS3/4A/Lap/LC-1 triple-transgenic mouse model that can be used to evaluate and screen NS3/4A protease inhibitors. The NS3/4A protease could be conditionally inducibly expressed in the livers of the triple-transgenic mice using a dual Tet-On and Cre/loxP system. In this system, doxycycline (Dox) induction resulted in the secretion of Gaussia luciferase (Gluc) into the blood, and this secretion was dependent on NS3/4A protease-mediated cleavage at the 4B5A junction. Accordingly, NS3/4A protease activity could be quickly assessed in real time simply by monitoring Gluc activity in plasma. The results from such monitoring showed a 70-fold increase in Gluc activity levels in plasma samples collected from the triple-transgenic mice after Dox induction. Additionally, this enhanced plasma Gluc activity was well correlated with the induction of NS3/4A protease expression in the liver. Following oral administration of the commercial NS3/4A-specific inhibitors telaprevir and boceprevir, plasma Gluc activity was reduced by 50% and 65%, respectively. Overall, our novel transgenic mouse model offers a rapid real-time method to evaluate and screen potential NS3/4A protease inhibitors. PMID:26943641

  5. Conditional Inducible Triple-Transgenic Mouse Model for Rapid Real-Time Detection of HCV NS3/4A Protease Activity.

    PubMed

    Yao, Min; Lu, Xin; Lei, Yingfeng; Yang, Jing; Zhao, Haiwei; Qiao, Qinghua; Han, Peijun; Xu, Zhikai; Yin, Wen

    2016-01-01

    Hepatitis C virus (HCV) frequently establishes persistent infections that can develop into severe liver disease. The HCV NS3/4A serine protease is not only essential for viral replication but also cleaves multiple cellular targets that block downstream interferon activation. Therefore, NS3/4A is an ideal target for the development of anti-HCV drugs and inhibitors. In the current study, we generated a novel NS3/4A/Lap/LC-1 triple-transgenic mouse model that can be used to evaluate and screen NS3/4A protease inhibitors. The NS3/4A protease could be conditionally inducibly expressed in the livers of the triple-transgenic mice using a dual Tet-On and Cre/loxP system. In this system, doxycycline (Dox) induction resulted in the secretion of Gaussia luciferase (Gluc) into the blood, and this secretion was dependent on NS3/4A protease-mediated cleavage at the 4B5A junction. Accordingly, NS3/4A protease activity could be quickly assessed in real time simply by monitoring Gluc activity in plasma. The results from such monitoring showed a 70-fold increase in Gluc activity levels in plasma samples collected from the triple-transgenic mice after Dox induction. Additionally, this enhanced plasma Gluc activity was well correlated with the induction of NS3/4A protease expression in the liver. Following oral administration of the commercial NS3/4A-specific inhibitors telaprevir and boceprevir, plasma Gluc activity was reduced by 50% and 65%, respectively. Overall, our novel transgenic mouse model offers a rapid real-time method to evaluate and screen potential NS3/4A protease inhibitors. PMID:26943641

  6. Asymmetrically driven implosions

    SciTech Connect

    Vaughan, K.; McAlpin, S.; Foster, J. M.; Stevenson, R. M.; Glendinning, S. G.; Sorce, C.

    2010-05-15

    Techniques to achieve uniform near-spherical symmetry of radiation drive on a capsule in a laser-heated hohlraum have received detailed attention in the context of inertial confinement fusion. However, much less attention has been paid to the understanding of the hohlraum physics in cases where the radiation drive departs significantly from spherical symmetry. A series of experiments has been carried out to study the implosion dynamics of a capsule irradiated by a deliberately asymmetric x-ray drive. The experimental data provide a sensitive test of radiation transport in hohlraums in which drive symmetry is modulated by asymmetric laser beam timing and the use of wall materials of different albedos. Data from foam ball and thin-shell capsule experiments are presented together with modeling using consecutively linked Lagrangian and Eulerian calculational schemes. The thin-shell capsules exhibit much stronger sensitivity to early-time asymmetry than do the foam balls, and this sensitivity results in the formation of a well-defined polar jet. These data are shown to challenge computational modeling in this highly asymmetric convergent regime. All of the experiments detailed were carried out at the OMEGA laser facility [J. M. Soures, R. L. McCrory, C. P. Verdon et al., Phys. Plasmas 3, 2108 (1996)] at the Laboratory for Laser Energetics in Rochester, NY.

  7. Magnetic Rayleigh-Taylor instability mitigation in large-diameter gas puff Z-pinch implosions

    SciTech Connect

    Qi, N.; Sze, H.; Failor, B. H.; Banister, J.; Levine, J. S.; Riordan, J. C.; Steen, P.; Sincerny, P.; Lojewski, D.

    2008-02-15

    Recently, a new approach for efficiently generating K-shell x-rays in large-diameter, long-implosion time, structured argon gas Z-pinches has been demonstrated based on a 'pusher-stabilizer-radiator' model. In this paper, direct observations of the Rayleigh-Taylor instability mitigation of a 12-cm diameter, 200-ns implosion time argon Z-pinch using a laser shearing interferometer (LSI) and a laser wavefront analyzer (LWA) are presented. Using a zero-dimensional snowplow model, the imploding plasma trajectories are calculated with the driver current waveforms and the initial mass distributions measured using the planar laser induced fluorescence method. From the LSI and LWA images, the plasma density and trajectory during the implosion are measured. The measured trajectory agrees with the snowplow calculations. The suppression of hydromagnetic instabilities in the ''pusher-stabilizer-radiator'' structured loads, leading to a high-compression ratio, high-yield Z-pinch, is discussed. For comparison, the LSI and LWA images of an alternative load (without stabilizer) show the evolution of a highly unstable Z-pinch.

  8. ns-time resolution for multispecies STED-FLIM and artifact free STED-FCS

    NASA Astrophysics Data System (ADS)

    Koenig, Marcelle; Reisch, Paja; Dowler, Rhys; Kraemer, Benedikt; Tannert, Sebastian; Patting, Matthias; Clausen, Mathias P.; Galiani, Silvia; Eggeling, Christian; Koberling, Felix; Erdmann, Rainer

    2016-03-01

    Stimulated Emission Depletion (STED) Microscopy has evolved into a well established method offering optical superresolution below 50 nm. Running both excitation and depletion lasers in picosecond pulsed modes allows for highest optical resolution as well as fully exploiting the photon arrival time information using time-resolved single photon counting (TCSPC). Non-superresolved contributions can be easily dismissed through time-gated detection (gated STED) or a more detailed fluorescence decay analysis (FLIM-STED), both leading to an even further improved imaging resolution. Furthermore, these methods allow for accurate separation of different fluorescent species, especially if subtle differences in the excitation and emission spectra as well as the fluorescence decay are taken into account in parallel. STED can also be used to shrink the observation volume while studying the dynamics of diffusing species in Fluorescence Correlation Spectroscopy (FCS) to overcome averaging issues along long transit paths. A further unique advantage of STED-FCS is that the observation spot diameter can be tuned in a gradual manner enabling, for example, determining the type of hindered diffusion in lipid membrane studies. Our completely pulsed illumination scheme allows realizing an improved STED-FCS data acquisition using pulsed interleaved excitation (PIE). PIE-STED-FCS allows for a straightforward online check whether the STED laser has an influence on the investigated diffusion dynamics.

  9. Buoyancy instability of homologous implosions

    SciTech Connect

    Johnson, B. M.

    2015-06-15

    With this study, I consider the hydrodynamic stability of imploding ideal gases as an idealized model for inertial confinement fusion capsules, sonoluminescent bubbles and the gravitational collapse of astrophysical gases. For oblate modes (short-wavelength incompressive modes elongated in the direction of the mean flow), a second-order ordinary differential equation is derived that can be used to assess the stability of any time-dependent flow with planar, cylindrical or spherical symmetry. Upon further restricting the analysis to homologous flows, it is shown that a monatomic gas is governed by the Schwarzschild criterion for buoyant stability. Under buoyantly unstable conditions, both entropy and vorticity fluctuations experience power-law growth in time, with a growth rate that depends upon mean flow gradients and, in the absence of dissipative effects, is independent of mode number. If the flow accelerates throughout the implosion, oblate modes amplify by a factor (2C)|N0|ti, where C is the convergence ratio of the implosion, N0 is the initial buoyancy frequency and ti is the implosion time scale. If, instead, the implosion consists of a coasting phase followed by stagnation, oblate modes amplify by a factor exp(π|N0|ts), where N0 is the buoyancy frequency at stagnation and ts is the stagnation time scale. Even under stable conditions, vorticity fluctuations grow due to the conservation of angular momentum as the gas is compressed. For non-monatomic gases, this additional growth due to compression results in weak oscillatory growth under conditions that would otherwise be buoyantly stable; this over-stability is consistent with the conservation of wave action in the fluid frame. The above analytical results are verified by evolving the complete set of linear equations as an initial value problem, and it is demonstrated that oblate modes are the fastest

  10. Buoyancy instability of homologous implosions

    DOE PAGESBeta

    Johnson, B. M.

    2015-06-15

    With this study, I consider the hydrodynamic stability of imploding ideal gases as an idealized model for inertial confinement fusion capsules, sonoluminescent bubbles and the gravitational collapse of astrophysical gases. For oblate modes (short-wavelength incompressive modes elongated in the direction of the mean flow), a second-order ordinary differential equation is derived that can be used to assess the stability of any time-dependent flow with planar, cylindrical or spherical symmetry. Upon further restricting the analysis to homologous flows, it is shown that a monatomic gas is governed by the Schwarzschild criterion for buoyant stability. Under buoyantly unstable conditions, both entropy andmore » vorticity fluctuations experience power-law growth in time, with a growth rate that depends upon mean flow gradients and, in the absence of dissipative effects, is independent of mode number. If the flow accelerates throughout the implosion, oblate modes amplify by a factor (2C)|N0|ti, where C is the convergence ratio of the implosion, N0 is the initial buoyancy frequency and ti is the implosion time scale. If, instead, the implosion consists of a coasting phase followed by stagnation, oblate modes amplify by a factor exp(π|N0|ts), where N0 is the buoyancy frequency at stagnation and ts is the stagnation time scale. Even under stable conditions, vorticity fluctuations grow due to the conservation of angular momentum as the gas is compressed. For non-monatomic gases, this additional growth due to compression results in weak oscillatory growth under conditions that would otherwise be buoyantly stable; this over-stability is consistent with the conservation of wave action in the fluid frame. The above analytical results are verified by evolving the complete set of linear equations as an initial value problem, and it is demonstrated that oblate modes are the fastest-growing modes and that high mode numbers are required to reach this limit (Legendre mode ℓ ≳ 100

  11. Implosion of indirect-drive fast ignition targets with CH coated reentrant cone

    NASA Astrophysics Data System (ADS)

    Zhou, Weimin; Shan, Lianqiang; Gu, Yuqiu; Zhang, Baohan; Fast Ignition Team

    2014-10-01

    Compared with central ignition of laser fusion, fast ignition separates compression and ignition thus it can relax the requirements on the implosion symmetry and the driven energy. The implosion of indirect-drive fast ignition targets with CH coated reentrant cone was experimentally researched on SHENGUANG (SG) II laser facility. The small scale cone-in-shell target fast ignition was pre-compressed by the SG II eight 260 J/1 ns/3 ω laser beams indirectly since beam smoothing was not available currently. The maximum density of the compressed cone-in-shell target 1.37 ns after the lasers' irradiation on the inside wall of hohlraum is about 8.7 g/cm3, and the areal density is close to 8.9 mg/cm2, which are well consistent with the simulation results with two-dimensional radiation hydrodynamic code. To minimize the mixing of the compressed fuel and high-Z vapor produced by the M-line emission from the gold holhraum, a 3 μm CH foil was coated on the full outer surface of the cone and guiding wire. Experimental results and simulation results also demonstrated the coated CH foil could minimize the mixing effectively. By the appropriate design, target can remain robust before the maximum compression, that is, the time while the hot electrons produced by ignition laser pulse deposit energy in the compressed fuel.

  12. Dynamics of conical wire array Z-pinch implosions

    SciTech Connect

    Ampleford, D. J.; Lebedev, S. V.; Bland, S. N.; Bott, S. C.; Chittenden, J. P.; Jennings, C. A.; Kantsyrev, V. L.; Safronova, A. S.; Ivanov, V. V.; Fedin, D. A.; Laca, P. J.; Yilmaz, M. F.; Nalajala, V.; Shrestha, I.; Williamson, K.; Osborne, G.; Haboub, A.; Ciardi, A.

    2007-10-15

    A modification of the wire array Z pinch, the conical wire array, has applications to the understanding of wire array implosions and potentially to pulse shaping relevant to inertial confinement fusion. Results are presented from imploding conical wire array experiments performed on university scale 1 MA generators--the MAGPIE generator (1 MA, 240 ns) at Imperial College London [I. H. Mitchell et al., Rev. Sci Instrum. 67, 1533 (1996)] and the Nevada Terawatt Facility's Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno [B. Bauer et al., in Dense Z-Pinches, edited by N. Pereira, J. Davis, and P. Pulsifer (AIP, New York, 1997), Vol. 409, p. 153]. This paper will discuss the implosion dynamics of conical wire arrays. Data indicate that mass ablation from the wires in this complex system can be reproduced with a rocket model with fixed ablation velocity. Modulations in the ablated plasma are present, the wavelength of which is invariant to a threefold variation in magnetic field strength. The axial variation in the array leads to a zippered precursor column formation. An initial implosion of a magnetic bubble near the cathode is followed by the implosion zippering upwards. Spectroscopic data demonstrating a variation of plasma parameters (e.g., electron temperature) along the Z-pinch axis is discussed, and experimental data are compared to magnetohydrodynamic simulations.

  13. Compton Radiography of ICF implosions

    NASA Astrophysics Data System (ADS)

    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.

  14. Long implosion PRS experiments on Double-EAGLE

    SciTech Connect

    Levine, J.S.; Coleman, P.L.; Failor, B.H.

    1999-07-01

    Previous research on the high-power generators DM2, at Maxwell Physics International, and Saturn, at Sandia National laboratories, has demonstrated that long-implosion (200--300 ns) PRS sources, both gas puff and wire load, can be sufficiently stable to produce well-assembled pinches and high-power radiation pulses of soft x-rays (1--4 keV). This has substantial implications for reducing the cost and risk of future higher current facilities (e.g., Decade Quad). To extend their knowledge and understanding of long-implosion sources, the authors are conducting a well-diagnosed series of experiments on long-pulse Double-EAGLE (4 MA at 200 ns). Results from Ar gas puffs, with various nozzles and valves, and Al wire arrays will be presented. Where possible, comparison with short-pulse results will be discussed.

  15. Foil implosion studies on PEGASUS

    SciTech Connect

    Cochrane, J.C.; Bartsch, R.R.; Begay, F.; Kruse, H.W.; Oona, H.; Parker, J.V.; Turchi, P.J.

    1989-01-01

    PEGASUS is a 1.5 MJ capacitor bank facility used in the Los Alamos Trailmaster foil implosion program. The experiments on this facility are to serve as a diagnostic testbed and foil physics benchmark for foil implosions with explosive generators as drivers. During the first year of operation, foil implosions have been driven by discharging the bank directly into a very thin Aluminum 2500 /angstrom/ thick free-standing foil without any pulse sharpening techniques; so-called ''direct drive.''These direct drive experiments have served as initial tests to optimize bank performance and foil implosion experimental techniques. The results to date are presented below. 1 ref., 2 figs.

  16. Improved hohlraums for high foot implosions

    NASA Astrophysics Data System (ADS)

    Hinkel, D. E.; Berzak Hopkins, L. F.; Ralph, J.; Schneider, M. B.; Kline, J. L.; Turnbull, D. P.; Call, D. A.; Hurricane, O. A.

    2015-11-01

    Recent High Foot implosions at the National Ignition Facility (NIF), where the laser power is high early in time, have resulted in record neutron yields. In these implosions, there is evidence of low mode radiation drive asymmetries impacting both in-flight and hot spot symmetry. Simulations suggest these asymmetries reduce neutron yield 2-4x, and thus improving the hohlraum should ameliorate implosion performance. To improve symmetry, a hohlraum 1.18x larger with a lower gas fill density has been designed and is being tested. This larger hohlraum with intermediate fill density has performed well for the shorter pulse lengths driving implosions with high-density carbon (HDC) ablators. The challenge here is to maintain the predictability shown by simulation at the longer pulse lengths necessary for plastic ablators. Upcoming shots provide the first tests of drive symmetry and deficit as well as laser backscatter in these larger hohlraums with an intermediate gas fill density using the longer High Foot pulse. Results will be presented and compared to design. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Measurements of the Conduction-Zone Length and Mass Ablation Rate in Cryogenic Direct-Drive Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Michel, D. T.; Davis, A. K.; Goncharov, V. N.; Sangster, T. C.; Hu, S. X.; Igumenshchev, I. V.; Meyerhofer, D. D.; Seka, W.; Froula, D. H.

    2015-04-01

    Measurements of the conduction-zone length (110 ±20 μ m at t =2.8 ns ), the averaged mass ablation rate of the deuterated plastic (7.95 ±0.3 μ g /ns ), shell trajectory, and laser absorption are made in direct-drive cryogenic implosions and are used to quantify the electron thermal transport through the conduction zone. Hydrodynamic simulations that use nonlocal thermal transport and cross-beam energy transfer models reproduce these experimental observables. Hydrodynamic simulations that use a time-dependent flux-limited model reproduce the measured shell trajectory and the laser absorption but underestimate the mass ablation rate by ˜10 % and the length of the conduction zone by nearly a factor of 2.

  18. Measurements of the conduction-zone length and mass ablation rate in cryogenic direct-drive implosions on OMEGA

    SciTech Connect

    Michel, D. T.; Davis, A. K.; Goncharov, V. N.; Sangster, T. C.; Hu, S. X.; Igumenshchev, I. V.; Meyerhofer, D. D.; Seka, W.; Froula, D. H.

    2015-04-14

    Measurements of the conduction-zone length (110 ± 20 μm at t = 2.8 ns), the averaged mass ablation rate of the deuterated plastic (7.95 ± 0.3 μg/ns), shell trajectory, and laser absorption are made in direct-drive cryogenic implosions and are used to quantify the electron thermal transport through the conduction zone. Hydrodynamic simulations that use nonlocal thermal transport and cross-beam energy transfer models reproduce these experimental observables. Hydrodynamic simulations that use a time-dependent flux-limited model reproduce the measured shell trajectory and the laser absorption but underestimate the mass ablation rate by ~10% and the length of the conduction zone by nearly a factor of 2.

  19. X-pinch dynamics: Neck formation and implosion

    SciTech Connect

    Oreshkin, V. I.; Chaikovsky, S. A.; Artyomov, A. P.; Labetskaya, N. A.; Fedunin, A. V.; Rousskikh, A. G.; Zhigalin, A. S.

    2014-10-15

    We propose a model that describes the neck formation and implosion in an X-pinch. The process is simulated to go in two stages. The first stage is neck formation. This stage begins with an electrical explosion of the wires forming the X-pinch, and at the end of the stage, a micropinch (neck) is formed in the region where the wires are crossed. The second stage is neck implosion. The implosion is accompanied by outflow of matter from the neck region, resulting in the formation of a “hot spot”. Analytical estimates obtained in the study under consideration indicate that these stages are approximately equal in duration. Having analyzed the neck implosion dynamics, we have verified a scaling which makes it possible to explain the observed dependences of the time of occurrence of an x-ray pulse on the X-pinch current and mass.

  20. Effects of nonlocal heat transport on laser implosion

    SciTech Connect

    Mima, K.; Honda, M.; Miyamoto, S.; Kato, S.

    1996-05-01

    A numerical simulation code describing the spherically symmetric implosion hydrodynamics has been developed to investigate the nonlocal heat transport effects on stable high velocity implosion and fast ignition. In the implosion simulation code HIMICO, the Fokker Planck equation for electron transport is solved to describe the nonlocal effects. For high ablation pressure implosion with a pressure higher than 200 Mbar, the isentrope is found higher by a factor 2 in the nonlocal transport model than in the Spitzer Harm model. As for the fast ignition simulation, the neutron yield for the high density compression with 10 KJ laser increases to be 20 times by injecting an additional heating pulse of 10 KJ with 1 psec. {copyright} {ital 1996 American Institute of Physics.}

  1. Direct drive implosion experiments on SGIII prototype laser facility: Assessing energy coupling efficiency and implosion symmetry

    SciTech Connect

    Pu Yudong; Huang Tianxuan; Li Huang; Zhan Xiayu; Peng Xiaoshi; Tang Qi; Song Zifeng; Chen Jiabin; Song Tianming; Chen Ming; Yu Ruizhen; He Xiaoan; Li Chaoguang; Zhang Lu; Zheng Jiahua; Jing Longfei; Chen Bolun; Su Ming; Jiang Wei; Yu Bo; and others

    2012-07-15

    Direct drive implosion experiments were conducted on SGIII prototype laser facility. From the time resolved x-ray images, the bright ring and the central bright spot are observed. The radial velocity of the convergent bright ring indicates the shell velocity, and the times when the central bright spot is first seen and becomes most intensive indicate the times of shock convergence and later stagnation, respectively. Radiation hydrodynamic simulations were carried out by changing laser energy deposition factors. When the simulated results are brought close to the measured ones, it is found that the energy coupling efficiency is around 70%. The implosion symmetry is indicated by the core x-ray emission pattern which is pancake when viewing from the equator, and splits into several bright spots when viewing close to the pole. A simple model is developed to understand this asymmetry. It is speculated that the observed implosion asymmetry can be attributed to the laser arrangement which is originally designed for indirect drive experiments. Further improvements of energy coupling efficiency and implosion symmetry in future experiments can be achieved by optimizing target design and laser arrangement.

  2. Multimegajoule electromagnetic implosion of shaped solid-density liners

    SciTech Connect

    Degnan, J.H.; Baker, W.L.; Alme, M.L.

    1995-03-01

    Electromagnetic implosions of shaped cylindrical aluminum liners that remain at solid density are discussed. The approximate liner parameters have an initial radius of 3 to 4 cm, are 4 cm in height, and are nearly 0.1 cm thick. The liners are driven by the Shiva Star 1300-{mu}f capacitor bank at an 84-kV charging voltage and an nearly 30-nH total initial inductance (including implosion load). The discharge current travels along the length of the liner and rises to 14 MA in nearly 8 {mu}s. The implosion time is nearly 12 {mu}s. Diagnostics include inductive current and capacitive voltage probes, magnetic probes, and radiography. Both right-circular cylinder and conical liner implosion data are displayed and discussed. Radiography indicates implosion behavior substantially consistent with two-dimensional magnetohydrodynamic calculations, which predict inner surface implosion velocities exceeding 20 km/s, and compressed density of two to three times solid density. Less growth of perturbations is evident for the conical liner (nearly 1% thickness tolerance) than for the right-circular cylindrical liner (nearly 3% thickness tolerance). 12 refs., 8 figs.

  3. Isochoric implosions for fast ignition

    SciTech Connect

    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.

  4. Time Evolution and Asymmetries of OMEGA Direct-Drive D^3He Capsule Implosions Inferred from 3.0- and 14.7-MeV Protons and 3.6-MeV Alphas

    NASA Astrophysics Data System (ADS)

    Seguin, F. H.; Petrasso, R. D.; Frenje, J. A.; Li, C. K.; Rygg, J. R.; Stoeckl, C.; Radha, P. B.; Delettrez, J. A.; Glebov, V. N.; Meyerhofer, D. D.; Sangster, T. C.; Soures, J. M.

    2002-11-01

    Fusion of D and ^3He in direct-drive, spherical-capsule implosions results in the copious production of several charged fusion products that lose energy as they pass out through the hot fuel plasma and the cool (<=1 keV) shell plasma. Energy losses reflect the areal density (ρ L) of the plasma transited at the instant of burn. In experiments on OMEGA, up to 11 spectrometers were used to simultaneously measure spectra of D^3He protons from different directions for information about the symmetry and time evolution of ρL. There are often significant differences in the individual spectra from one implosion, both in mean energy loss and in maximum energy loss, which largely reflect nonuniformities in the shell. D^3He protons are also produced at first shock coalescence when the capsule is far less compressed, and they escape with energy losses indicating lower areal densities at that time. We examine whether asymmetries are detectable at first shock coalesence, and whether they are then amplified by bang time. This work was supported in part by the U.S. DOE Office of Inertial Confinement Fusion (Grant number DE-FG03-99DP00300 and Cooperative Agreement number DE-FC03-92SF19460), LLE (subcontract P0410025G), LLNL (subcontract B313975). (Petrasso: Visiting Senior Scientist at LLE.)

  5. Change in inertial confinement fusion implosions upon using an ab initio multiphase DT equation of state.

    PubMed

    Caillabet, L; Canaud, B; Salin, G; Mazevet, S; Loubeyre, P

    2011-09-01

    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 target [S. X. Hu et al., Phys. Rev. Lett. 104, 235003 (2010)]. Here we use an advanced multiphase 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 (3 ns) in the shock timing of the implosion. PMID:22026681

  6. Isochoric Implosions for Fast Ignition

    NASA Astrophysics Data System (ADS)

    Clark, Daniel; Tabak, Max

    2006-10-01

    Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hotspot ignition counterpart. These gain models, however, all assume nearly uniform-density fuel assemblies. By contrast, typical ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hotspot. To realize fully the advantages of FI, then, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hotspots. 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, i.e., accessible peak pressures, shell aspect ratios, etc. An implosion scheme is presented which meets all of these requirements, suggesting the possibility of genuinely isochoric implosions for FI.

  7. Gas puff Z-pinch implosions with external Bz field on COBRA

    NASA Astrophysics Data System (ADS)

    Qi, N.; de Grouchy, P.; Schrafel, P. C.; Atoyan, L.; Potter, W. M.; Cahill, A. D.; Gourdain, P.-A.; Greenly, J. B.; Hammer, D. A.; Hoyt, C. L.; Kusse, B. R.; Pikuz, S. A.; Shelkovenko, T. A.

    2014-12-01

    We present preliminary experimental results on mitigating Magneto-Rayleigh-Taylor (MRT) instabilities by applying an external Bz field. The experiments were conducted on the 1-MA, 200-ns COBRA generator at Cornell University. In the experiments, a triple-nozzle was used to produce z-pinch loads from concentric outer and inner annular gas puffs and a center gas puff column. A single coil was used to produce a Bz field in the pinch region. We have used two 4-frame 2-ns gated EUV cameras to obtain images of the imploding plasmas, in which the MRT instabilities were observed. The MRT instabilities can grow when the plasma accelerates toward the axis. With a triple gas puff (outer, inner and center puff), reduced acceleration or de-acceleration of the imploding plasma occurred when the outer puff plasma imploded onto the inner annular puff plasma resulting a relatively stable implosion. In the absent of the inner annular gas puff, the imploding outer annular plasma continued to accelerate toward the axis. Large turbulent flares at the edge of the implosion or pinch plasma were observed. The implosion was not stable. To stabilize the implosion without the inner gas puff, a Bz field was applied. This external Bz field was compressed by the outer imploding plasma shell. A relatively stable implosion was observed. Increasing the Bz field to 2-kG resulted in a relatively fatter pinch plasma.

  8. Radius scaling of X-radiation from gas-puff implosions on an inductive driver

    SciTech Connect

    Mosher, D.; Stephanakis, S. J.; Apruzese, J. P.; Black, D. C.; Boller, J. R.; Commisso, R. J.; Myers, M. C.; Peterson, G. G.; Weber, B. V.; Young, F. C.

    1997-05-05

    The output of X radiation from gas-puff implosions is studied in reference to its theoretical prediction by simple model. Results show that the gas-puff radius, but not implosion time, controls radiation yield. Radius-scaling models being fairly reliable may lead to an overestimation sometimes. (AIP)

  9. Isochoric Implosions for Fast Ignition

    SciTech Connect

    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.

  10. Buoyancy instability of homologous implosions

    NASA Astrophysics Data System (ADS)

    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).

  11. Plasma Effects in Spherical Implosions

    NASA Astrophysics Data System (ADS)

    Bellei, Claudio; Amendt, Peter; Wilks, Scott

    2011-10-01

    A remarkable self-similar solution to the problem of a spherically converging shock was published by Guderley in 1942. Being applicable to an ideal gas, this solution neglects viscosity, thermal conduction and radiation losses and presents singularities when the shock reaches the origin. Radiation hydrodynamic codes include the effects of non-ideality (with artificial viscosity in place of real viscosity), ensuring that the solution is well-behaved at all times. However during an ICF implosion, separation of the electron and ion species occurs at the shock front. For the high Mach number (M > 10) incoming (coalesced) shock that is typical of ICF scenarios, the width of the plasma shock front is comparable to the ion-ion mean-free-path λii ~ 1 μ m and much larger than the shock front width in an unionized gas at the same density (~10-2 μ m). Ahead of the plasma shock front, electrons pre-heat the inner gas over distances λei ~(mi /me) 1 / 2λii ~ 70 μ m. This decreases the strength of the incoming shock and lowers the temperature behind the rebound shock, a phenomenon analogous to the non-ideal gas effects found in hydro-codes. Prepared by LLNL under Contract DE-AC52-07NA27344.

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

    SciTech Connect

    Zylstra, A. B. 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.; Rygg, J. R.; Kritcher, A.; Hicks, D. G.; Friedrich, S.; Bionta, R.; Meezan, N. B.; Atherton, J.; Barrios, M.; Bell, P.; 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.

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

    DOE PAGESBeta

    Zylstra, A. B.; Frenje, J. A.; Seguin, F. H.; Rygg, J. R.; Kritcher, A.; Rosenberg, M. J.; Rinderknecht, H. G.; Hicks, D. G.; Friedrich, S.; Bionta, R.; et al

    2015-05-01

    Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale indirect-drive implosions for the first time. Surrogate D3He gas-filled implosions at the National Ignition Facility produce energetic protons via D+3He 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 aremore » 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.« less

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

    SciTech Connect

    Zylstra, A. B.; Frenje, J. A.; Seguin, F. H.; Rygg, J. R.; Kritcher, A.; Rosenberg, M. J.; Rinderknecht, H. G.; Hicks, D. G.; Friedrich, S.; Bionta, R.; Meezan, N. B.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Berzak Hopkins, L.; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dewald, E. L.; Dixit, S.; Doppner, T.; Edwards, M. J.; Gatu Johnson, M.; Glenn, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moses, E.; Nagel, S. R.; Nikroo, A.; Parham, T.; Pak, A.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Robey, H. F.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Yeamans, C.; Zacharias, R.

    2015-05-01

    Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale indirect-drive implosions for the first time. Surrogate D3He gas-filled implosions at the National Ignition Facility produce energetic protons via D+3He 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. Mitigation of the Plasma-Implosion Inhomogeneity in Starlike Wire-Array Z Pinches

    SciTech Connect

    Ivanov, V. V.; Sotnikov, V. I.; Haboub, A.; Astanovitskiy, A. L.; Morozov, A.; Altemara, S. D.; Shevelko, A. P.; Kazakov, E. D.

    2008-01-18

    Implosions in starlike triple and quadruple wire arrays were investigated in a 1 MA Zebra generator. Implosion in these loads is directed along the rays of the star and cascades from wire to wire to the center. Shadowgraphy shows improved homogeneity of imploding plasma and mitigation of instabilities. Despite the low azimuthal symmetry, starlike wire arrays produce a stable x-ray pulse with the highest peak power of >0.4 TW and the shortest duration of 8-12 ns among different types of tested loads. This can be linked to stabilization of instabilities due to the multiple nesting.

  16. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: A progress report

    NASA Astrophysics Data System (ADS)

    Bennett, G. R.; Smith, I. C.; Shores, J. E.; Sinars, D. B.; Robertson, G.; Atherton, B. W.; Jones, M. C.; Porter, J. L.

    2008-10-01

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26MA Z Accelerator, the terawatt-class, multikilojoule, 526.57nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151keV (1s2-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing "two-frame" imaging to be performed, with an interframe time range of 2-20ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151keV two frame technique has recently been used to image imploding wire arrays, using a 7.3ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181keV Mn 1s2-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast (1ns gate time

  17. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: A progress report

    SciTech Connect

    Bennett, G. R.; Smith, I. C.; Shores, J. E.; Sinars, D. B.; Robertson, G.; Atherton, B. W.; Jones, M. C.; Porter, J. L.

    2008-10-15

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26 MA Z Accelerator, the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV (1s{sup 2}-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1 mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing 'two-frame' imaging to be performed, with an interframe time range of 2-20 ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151 keV two frame technique has recently been used to image imploding wire arrays, using a 7.3 ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181 keV Mn 1s{sup 2}-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast

  18. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: a progress report.

    PubMed

    Bennett, G R; Smith, I C; Shores, J E; Sinars, D B; Robertson, G; Atherton, B W; Jones, M C; Porter, J L

    2008-10-01

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26 MA Z Accelerator, the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV (1s(2)-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1 mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing "two-frame" imaging to be performed, with an interframe time range of 2-20 ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151 keV two frame technique has recently been used to image imploding wire arrays, using a 7.3 ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181 keV Mn 1s(2)-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast (1 ns

  19. High convergence implosion symmetry in cylindrical hohlraums

    SciTech Connect

    Amendt, P A; Bradley, D K; Hammel, B A; Landen, O L; Suter, L J; Turner, R E; Wallace, R J

    1999-09-01

    High convergence, hohlraum-driven implosions will require control of time-integrated drive asymmetries to 1% levels for ignition to succeed on the NIF. We review how core imaging provides such asymmetry measurement accuracy for the lowest order asymmetry modes, and describe recent improvements in imaging techniques that should allow detection of higher order asymmetry modes. We also present a simple analytic model explaining how the sensitivity of symmetry control to beam pointing scales as we progress from single ring per side Nova cylindrical hohlraum illumination geometries to NIF-like multiple rings per side Omega hohlraum illumination geometries and ultimately to NIF-scale hohlraums.

  20. High-performance inertial confinement fusion target implosions on OMEGA

    SciTech Connect

    Meyerhofer, D. D.; McCrory, R L; Betti, R; Boehly, T R; Casey, D T; Collins, T.J.B.; Craxton, R S; Delettrez, J A; Edgell, D H; Epstein, R; Fletcher, K A; Frenje, J A; Glebov, Y Yu; Goncharov, V N; Harding, D R; Hu, S X; Igumenshchev, I V; Knauer, J P; Li, C K; Marozas, J A; Marshall, F J; McKenty, P W; Nilson, P M; Padalino, S P; Petrasso, R D; Radha, P B; Regan, S P; Sangster, T C; Seguin, F H; Seka, W; Short, R W; Shvarts, D; Skupsky, S; Soures, J M; Stoeckl, C; Theobald, W; Yaakobi, B

    2011-04-18

    The Omega Laser Facility is used to study inertial confinement fusion (ICF) concepts. This paper describes progress in direct-drive central hot-spot (CHS) ICF, shock ignition (SI) and fast ignition (FI) since the 2008 IAEA FEC conference. CHS cryogenic deuterium-tritium (DT) target implosions on OMEGA have produced the highest DT areal densities yet measured in ICF implosions (~300 mg cm{sup -2}). Integrated FI experiments have shown a significant increase in neutron yield caused by an appropriately timed high-intensity, high-energy laser pulse.

  1. Hemispherical Capsule Implosions for Fast Ignition*

    NASA Astrophysics Data System (ADS)

    Hanson, D. L.; Vesey, R. A.; Sinars, D. B.; Adams, R. G.; Cuneo, M. E.; Porter, J. L.; Slutz, S. A.; Johnston, R. R.; Wenger, D. F.; Schroen, D. G.

    2003-10-01

    The fast ignitor approach to ICF ignition separates the fuel assembly and fast heating processes. After compressing the fuel with the main driver, the fuel is ignited using a focused electron or ion beam generated by a fast, ultra-high power laser pulse. This significantly relaxes the drive symmetry, energy, and shock timing requirements compared to hot spot ignition. A hemispherical capsule target is a fast ignitor geometry well-adapted to symmetric fuel compression by a single-ended z-pinch radiation drive. The hemispherical capsule implodes radially, constrained at its equator by a flat high-density surface (a special case of the spherical capsule "cone-focus" geometry). This glide plane is mounted on a hollow pedestal that provides a plasma-free, short-pulse laser path to the compressed fuel core region. In experiments on the Z accelerator at Sandia, we are studying implosions of 2.0-mm-diameter, 60-micron-thick hemispherical capsules in cylindrical secondary hohlraums heated to 90-100 eV from one end by a 120 TW wire-array z-pinch. Analysis of ZBL 6.7 keV point-projection backlighter images of pole-hot implosions in a tall secondary and 6.18 keV monochromatic crystal backlighter images of more symmetric implosions in a short secondary will be presented. We will also discuss progress on the development of a cryogenic liquid fuel target for this fast ignitor compression geometry. * Sandia is a multiprogram 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. Efficient Radiation Production in Long Implosions of Structured Gas-Puff Z Pinch Loads from Large Initial Radius

    SciTech Connect

    Sze, H.; Banister, J.; Failor, B.H.; Levine, J.S.; Qi, N.; Sincerny, P.; Velikovich, A.L.; Davis, J.; Lojewski, D.

    2005-09-02

    We have proposed and demonstrated successfully a new approach for generating high-yield K-shell radiation with large-diameter gas-puff Z pinches. The novel load design consists of an outer region plasma that carries the current and couples energy from the driver, an inner region plasma that stabilizes the implosion, and a high-density center jet plasma that radiates. It increased the Ar K-shell yield at 3.46 MA in 200 ns implosions from 12 cm initial diameter by a factor of 2, to 21 kJ, matching the yields obtained earlier on the same accelerator with 100 ns implosions. A new ''pusher-stabilizer-radiator'' physical model is advanced to explain this result.

  3. Neutron production in deuterium gas-puff implosions on the refurbished Z accelerator.

    SciTech Connect

    Flicker, Dawn G.; Coverdale, Christine Anne; Velikovich, Aleksandr Lazarevich; Clark, R. W.; Chong, Y. K.; Davis, J.; Giuliani, J. L.

    2010-06-01

    It has been experimentally demonstrated that deuterium gas-puff implosions at >15 MA are powerful sources of fusion neutrons. Analysis of these experiments indicates that a substantial fraction of the obtained DD fusion neutron yields {approx} 3 x 10{sup 13}, about 50%, might have been of thermonuclear origin. The goal of our study is to estimate the scaling of the thermonuclear neutron yield from deuterium gas-puff implosions with higher load currents available after the refurbishment of Z, both in the short-pulse ({approx}100 ns) and in the long-pulse ({approx}300 ns) implosion regimes. We report extensive ID and 2D radiation-hydrodynamic simulations of such implosions. The mechanisms of ion heating to the fusion temperatures of 7-10 keV are essentially the same as used in structured gas-puff loads to generate high Ar K-shell yields: shock thermalization of the implosion kinetic energy and subsequent adiabatic heating of the on-axis plasma. We investigate the role of high-atomic-number gas that can be added to the outer shell to improve both energy coupling of the imploded mass to the generator and energy transfer to the inner part of the load, due to radiative losses that make the outer shell thin. We analyze the effect of imposed axial magnetic field {approx}30-100 kG, which can contribute both to stabilization of the implosion and to Joule heating of the imploded plasma. Our estimates indicate that thermonuclear DD neutron yields approaching 10 are within the reach on refurbished Z.

  4. Cylindrical Implosion Experiments using Laser Direct Drive

    NASA Astrophysics Data System (ADS)

    Tubbs, David

    1998-11-01

    Development of high-gain targets for the National Ignition Facility relies considerably on computational modeling, and it is important that our codes are validated against relevant experimental data in convergent geometry.(W. J. Krauser et al., Phys. Plasmas 3, 2084 (1996); D. C. Wilson et al., Phys. Plasmas 5, 1953 (1998)) In collaboration with the University of Rochester, we have begun a campaign of hydrodynamic instability experiments in cylindrical geometry using direct drive,(D. L. Tubbs et al., submitted to Laser and Particle Beams (1998); C. W. Barnes et al., submitted to Rev. Sci. Instrm. (1998)) building on our success in indirect drive.( W. W. Hsing et al., Phys. Plasmas 5, 1832 (1997); W. W. Hsing and N. M. Hoffman, Phys. Rev. Lett., 3876 (1997)) Cylindrical targets facilitate direct diagnostic access to the convergent, hydrodynamic flow. The energy advantage of direct drive and its excellent target-illumination symmetry (achieved at OMEGA through use of Distributed Phase Plates and SSD) permit more energetic implosions, larger target scale (hence greater diagnostic resolution), longer acceleration timescales, and higher convergence than were possible using indirect drive. We estimate that specific laser energy delivered to the target for direct drive at OMEGA is roughly 4 times that achieved for indirect drive at Nova. Our first experiments (January 1998) yield excellent data for the first highly symmetrical direct-drive implosions, with which we benchmark zeroth-order hydrodynamic simulations. Two-dimensional (2-D) LASNEX calculations, using as-shot laser power histories and no further physics adjustments, match measured target-implosion data within theoretical and experimental errors. In addition, 2-D LASNEX simulations of single-mode (m=28, azimuthally symmetric) perturbation growth agree well with data obtained during our first week of experiments. For 1.5-micron initial perturbation amplitude, we observe Rayleigh-Taylor growth factors of order 10

  5. Hohlraum Designs for High Velocity Implosions on NIF

    SciTech Connect

    Meezan, N B; Hicks, D G; Callahan, D A; Olson, R E; Schneider, M S; Thomas, C A; Robey, H F; Celliers, P M; Kline, J K; Dixit, S N; Michel, P A; Jones, O S; Clark, D S; Ralph, J E; Doeppner, T; MacKinnon, A J; Haan, S W; Landen, O L; Glenzer, S H; Suter, L J; Edwards, M J; Macgowan, B J; Lindl, J D; Atherton, L J

    2011-10-19

    In this paper, we compare experimental shock and capsule trajectories to design calculations using the radiation-hydrodynamics code HYDRA. The measured trajectories from surrogate ignition targets are consistent with reducing the x-ray flux on the capsule by about 85%. A new method of extracting the radiation temperature as seen by the capsule from x-ray intensity and image data shows that about half of the apparent 15% flux deficit in the data with respect to the simulations can be explained by HYDRA overestimating the x-ray flux on the capsule. The National Ignition Campaign (NIC) point-design target is designed to reach a peak fuel-layer velocity of 370 km/s by ablating 90% of its plastic (CH) ablator. The 192-beam National Ignition Facility laser drives a gold hohlraum to a radiation temperature (T{sub RAD}) of 300 eV with a 20 ns-long, 420 TW, 1.3 MJ laser pulse. The hohlraum x-rays couple to the CH ablator in order to apply the required pressure to the outside of the capsule. In this paper, we compare experimental measurements of the hohlraum T{sub RAD} and the implosion trajectory with design calculations using the code hydra. The measured radial positions of the leading shock wave and the unablated shell are consistent with simulations in which the x-ray flux on the capsule is artificially reduced by 85%. We describe a new method of inferring the T{sub RAD} seen by the capsule from time-dependent x-ray intensity data and static x-ray images. This analysis shows that hydra overestimates the x-ray flux incident on the capsule by {approx}8%.

  6. Near Real-Time Gyrotron Data Streaming and Data Acquisition with ns Resolution on the DIII-D ECH System

    NASA Astrophysics Data System (ADS)

    Torrezan, A. C.; Ponce, D.; Gorelov, Y. A.; Cengher, M.; Lohr, J.

    2014-10-01

    As part of the expansion and upgrade of the electron cyclotron heating (ECH) systen on DIII-D, a new data acquisition setup has been implemented to acquire and display waveform data from all gyrotrons in near real time with high time resolution. The data acquisition for each gyrotron system is based on a fast digitizer with 8 channels running at 2 MS/s/channel and a resolution of 14 bits. This enables the operator to monitor all gyrotron-relevant variables as well as fast diagnostic signals such as window arcs. The data are transferred to a local computer through a 132 MB/s PCI bus, and then are streamed to the ECH operator and to a local network attached storage using 1 GB Ethernet links. The data are displayed to the ECH operator by means of a graphical user interface developed in LabVIEW, replacing physical scopes. Acquired gyrotron data are accessible at DIII-D through a local database (PTDATA) connected to the ECH data acquisition system by an Ethernet line, a configuration that eliminates the need for legacy CAMAC hardware in the data link. Work supported by the US Department of Energy under DE-FC02-04ER54698.

  7. Shell asymmetry-driven hot-spot generation issues in high convergence ratio implosions on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Hurricane, Omar; Springer, Paul; Callahan, Debbie; Casey, Daniel; Dewald, Eduard; Dittrich, Thomas; Doeppner, Tilo; Hinkel, Denise; Hopkins, Laura Berzak; Kritcher, Andrea; Ma, Tammy; Macphee, Andrew; Milovich, Jose; Park, Hye-Sook; Patel, Prav; Ralph, Joseph; Robey, Harry; Ross, J. Steven; Salmonson, Jay; Spears, Brian; Smalyuk, Vladimir; Tommasini, Riccardo; Yeamans, Charles

    2015-11-01

    Much of the conceptual understanding, theory, and design of ICF implosions has been developed assuming a one-dimensional (1D) implosion. But what if the typical ICF implosion is not 1D? In this talk we present an overview of data and simulation results from recent high performance implosions on NIF that imply highly distorted implosions and an associated non-ideal hot-spot generation issue, even in cases where the bang-time emission (in x-rays and neutrons) from the implosion appears 1D. We present a simple extension of a semi-analytic dynamic implosion model that captures the key effect of localized thin-regions in an implosions shell (fuel +remaining ablator), via a leaking hot-spot picture, and discuss what the model implies about the physics we can't directly diagnose in our suite of implosions. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Investigation of implosion dynamics and magnetic fields in 1-MA wire arrays by optical probing diagnostics

    NASA Astrophysics Data System (ADS)

    Laca, P. J.; Sarkisov, G. S.

    2005-10-01

    Multiframe optical probing diagnostics were applied for the investigation of implosion dynamics and magnetic fields in z-pinch plasma of wire arrays and x-pinches at the Nevada Terawatt Facility (NTF). Five shadow frames per shot, with a long 34-ns or short 9-ns pulse train, presents fine details of plasma evolution in the wire array. A Faraday rotation diagnostic consists of identical shadow and Faraday channels, shearing air-wedge interferometer, and schlieren channel. Evolution of the wire array z-pinch in different regimes of implosion was investigated. Fast dynamics of bubbles in plasma streams were studied in detail. A current in the plasma column of Al wire arrays and magnetic bubbles were found by the Faraday rotation diagnostic.

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

    SciTech Connect

    Hayes, Anna; Grim, Gary; Jungnam, Jerry; Bradley, Paul; Rundberg, Bob; Wilhelmy, Jerry; Wilson, Doug

    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 the ideal

  10. Electric Fields Associated with Spherically Converging Shocks in Directly-Driven OMEGA Implosions

    NASA Astrophysics Data System (ADS)

    Li, C. K.; Zylstra, A.; Rosenberg, M. J.; Rinderknecht, H. G.; Frenje, J. A.; Seguin, F. H.; Petrasso, R. D.; Hu, S. X.; Betti, R.; Sangster, T. C.; Amendt, P. A.; Bellei, C.; Wilks, S. C.; Hoffman, N. M.; Nikroo, A.

    2014-10-01

    Time-gated, proton radiography provides direct measurements of radial electric fields and their temporal evolution in directly-driven capsule implosions. The experimental data indicate that such fields are associated with a spherically converging shock inside an imploding capsule. The implosions are simulated with the 2D hydrodynamic code DRACO. Several related mechanisms for generating such fields are discussed. The measurements provide physical insight into the structure, strength and dynamics of spherically converging shocks and have important implications in ICF implosion physics. This work was supported in part by the U.S. DOE, NLUF, LLNL and LLE.

  11. Charged-particle probing of x-ray-driven inertial-fusion implosions.

    PubMed

    Li, C K; Séguin, F H; Frenje, J A; Rosenberg, M; Petrasso, R D; Amendt, P A; Koch, J A; Landen, O L; Park, H S; Robey, H F; Town, R P J; Casner, A; Philippe, F; Betti, R; Knauer, J P; Meyerhofer, D D; Back, C A; Kilkenny, J D; Nikroo, A

    2010-03-01

    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. PMID:20110464

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Cryogneic-Target Performance and Implosion Physics Studies on OMEGA

    SciTech Connect

    Smalyuk, V.A.; Betti, R.; Boehly, T.R.; Craxton, R.S.; Delettrez, J.A.; Edgell, D.H.; Glebov, V.Yu.; Goncharov, V.N.; Harding, D.R.; Hu, S.X.; Knauer, J.P.; Marshall, F.J.; McCrory, R.L.; McKenty, P.W.; Meyerhofer, D.D.; Radha, R.B.; Regan, S.P.; Sangster, T.C.; Seka, W.; Short, R.W.; Shvarts, D.; Skupsky, S.; Soures, J.M.; Stoeckl, C.; Yaakobi, B.; Frenje, J.A.; Li, C.K.; Petrasso, R.D.; Seguin, F.H.

    2009-03-06

    Recent progress in direct-drive cryogenic implosions on the OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is reviewed. Ignition-relevant areal densities of ~200 mg/cm^2 in cryogenic D2 implosions with peak laser-drive intensities of ~5 x 10^14 W/cm^2 were previously reported [T. C. Sangster et al., Phys. Rev. Lett. 100, 185006 (2008)]. The laser intensity is increased to ~10^15 W/cm^2 to demonstrate ignition-relevant implosion velocities of 3–4 x 10^7 cm/ s, providing an understanding of the relevant target physics. Planar-target acceleration experiments show the importance of the nonlocal electron-thermal-transport effects for modeling the laser drive. Nonlocal and hot-electron preheat is observed to stabilize the Rayleigh–Taylor growth at a peak drive intensity of ~10^15 W/cm^2. The shell preheat caused by hot electrons generated by two-plasmon-decay instability was reduced by using Si-doped ablators. The measured compressibility of planar plastic targets driven with high-compression shaped pulses agrees well with one-dimensional simulations at these intensities. Shock mistiming has contributed to compression degradation of recent cryogenic implosions driven with continuous pulses. Multiple-picket (shock-wave) target designs make it possible for a more robust tuning of the shock-wave arrival times. Cryogenic implosions driven with double-picket pulses demonstrate somewhat improved compression performance at a peak drive intensity of ~10^15 W/cm^2.

  14. Demonstrating Ignition Hydrodynamic Equivalence in Cryogenic DT Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Goncharov, V. N.

    2013-10-01

    Demonstrating ignition hydrodynamic equivalence is one of the primary goals of direct-drive cryogenic implosions on OMEGA. It requires the shell reaching implosion velocities > 3.5 × 107 cm/s while maintaining the fuel adiabat below 3 and keeping the shell from breaking up as a result of the Rayleigh-Taylor instability. The cryogenic targets used for implosions on OMEGA are 860- μm-outer-diam CD shells filled with DT fuel. The shell thickness varies between 5 and 12 μm, and DT ice thickness between 40 and 65 μm. Experimental results demonstrate, however, that neutron-averaged areal density in excess of 80% and yields above 25% of 1-D predicted values are obtained if the fuel adiabat > 3.5 and shell in-flight aspect ratio (IFAR) is below 22. As the IFAR exceeds this value, the shell breaks up and the areal density and yield are reduced. Identifying the main source of shell nonuniformities that lead to performance degradation in low-adiabat designs is one of the main efforts of OMEGA cryogenic campaign. This talk will summarize progress in cryogenic target implosions over the last year and review the effect of target debris, early-time laser shinethrough, and fuel-pusher roughness on target performance. In addition, the effect of cross-beam energy transfer (a major source of hydroefficiency degradation in a direct-drive implosions) and its mitigation strategies (including high- Z ablator layers, beam zooming, and laser wavelength shifts) will be discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  15. A new spectrometer design for the x-ray spectroscopy of laser-produced plasmas with high (sub-ns) time resolutiona)

    NASA Astrophysics Data System (ADS)

    Bitter, M.; Hill, K. W.; Efthimion, P. C.; Delgado-Aparicio, L.; Pablant, N.; Lu, Jian; Beiersdorfer, P.; Chen, Hui

    2014-11-01

    This paper describes a new type of x-ray crystal spectrometer, which can be used in combination with gated x-ray detectors to obtain spectra from laser-produced plasmas with a high (sub-ns) time resolution. The spectrometer consists of a convex, spherically bent crystal, which images individual spectral lines as perfectly straight lines across multiple, sequentially gated, strip detectors. Since the Bragg-reflected rays are divergent, the distance between detector and crystal is arbitrary, so that this distance can be appropriately chosen to optimize the experimental arrangement with respect to the detector parameters. The spectrometer concept was verified in proof-of-principle experiments by imaging the Lβ1- and Lβ2-lines of tungsten, at 9.6735 and 9.96150 keV, from a micro-focus x-ray tube with a tungsten target onto a two-dimensional pixilated Pilatus detector, using a convex, spherically bent Si-422 crystal with a radius of curvature of 500 mm.

  16. A new spectrometer design for the x-ray spectroscopy of laser-produced plasmas with high (sub-ns) time resolution

    SciTech Connect

    Bitter, M. Hill, K. W.; Efthimion, P. C.; Delgado-Aparicio, L.; Pablant, N.; Lu, Jian; Beiersdorfer, P.; Chen, Hui

    2014-11-15

    This paper describes a new type of x-ray crystal spectrometer, which can be used in combination with gated x-ray detectors to obtain spectra from laser-produced plasmas with a high (sub-ns) time resolution. The spectrometer consists of a convex, spherically bent crystal, which images individual spectral lines as perfectly straight lines across multiple, sequentially gated, strip detectors. Since the Bragg-reflected rays are divergent, the distance between detector and crystal is arbitrary, so that this distance can be appropriately chosen to optimize the experimental arrangement with respect to the detector parameters. The spectrometer concept was verified in proof-of-principle experiments by imaging the Lβ{sub 1}- and Lβ{sub 2}-lines of tungsten, at 9.6735 and 9.96150 keV, from a micro-focus x-ray tube with a tungsten target onto a two-dimensional pixilated Pilatus detector, using a convex, spherically bent Si-422 crystal with a radius of curvature of 500 mm.

  17. Pseudo-three-dimensional simulation on stability of thin shell target implosion

    SciTech Connect

    Taguchi, T.; Mima, K.

    1995-07-01

    Pseudo-three-dimensional simulation method has been developed to analyze implosion stability of thin shell target in inertial confinement fusion. Nonlinear motion of a thin spherical surface driven by the pressure simulates the implosion of a shell target filled with fuel gas. The simulation shows that acceleration and deceleration of the shell give rise to the Rayleigh--Taylor instability and the instability prevents the target from being compressed uniformly. The results of the simulation show how the maximum volume compression ratio and breakup time of the target depend upon the initial perturbation amplitude. The new simulation scheme has also been applied to another shape of closed surfaces. The implosion phenomenon of the surface of torus is shown as an example. The toroidal target implosion is found to be more stable against the Rayleigh--Taylor instability than that of spherical targets. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Zylstra, A. B. 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.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M.; 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.

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

    SciTech Connect

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Hopkins, L. Berzak; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Döppner, T.; Edgell, D.; Edwards, M. J.; Johnson, M. Gatu; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.

    2014-11-03

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He 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 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR 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 pR. 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 pR.

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

    DOE PAGESBeta

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; et al

    2014-11-03

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He 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 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infermore » the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR 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 pR. 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 pR.« less

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

    NASA Astrophysics Data System (ADS)

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Berzak Hopkins, L.; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Döppner, T.; Edgell, D.; Edwards, M. J.; Gatu Johnson, M.; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.

    2014-11-01

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He 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 (Rcm) from the downshift of the shock-produced D3He 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.

  3. Implosion dynamics and radiation characteristics of wire-array Z pinches on the Cornell Beam Research Accelerator

    SciTech Connect

    McBride, R. D.; Shelkovenko, T. A.; Pikuz, S. A.; Hammer, D. A.; Greenly, J. B.; Kusse, B. R.; Douglass, J. D.; Knapp, P. F.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A.

    2009-01-15

    Experimental results are presented that characterize the implosion dynamics and radiation output of wire-array Z pinches on the 1-MA, 100-ns rise-time Cornell Beam Research Accelerator (COBRA) [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]. The load geometries investigated include 20-mm-tall cylindrical arrays ranging from 4 to 16 mm in diameter, and consisting of 8, 16, or 32 wires of either tungsten, aluminum, or Invar (64% iron, 36% nickel). Diagnostics fielded include an optical streak camera, a time-gated extreme-ultraviolet framing camera, a laser shadowgraph system, time-integrated pinhole cameras, an x-ray wide-band focusing spectrograph with spatial resolution, an x-ray streak camera, a load voltage monitor, a Faraday cup, a bolometer, silicon diodes, and diamond photoconducting detectors. The data produced by the entire suite of diagnostics are analyzed and presented to provide a detailed picture of the overall implosion process and resulting radiation output on COBRA. The highest x-ray peak powers (300-500 GW) and total energy yields (6-10 kJ) were obtained using 4-mm-diameter arrays that stagnated before peak current. Additional findings include a decrease in soft x-ray radiation prior to stagnation as the initial wire spacing was changed from 1.6 mm to 785 {mu}m, and a timing correlation between the onset of energetic electrons, hard x-ray generation, and the arrival of trailing current on axis - a correlation that is likely due to the formation of micropinches. The details of these and other findings are presented and discussed.

  4. Results from directly driven implosions of deuterated plastic shells filled with tritium gas

    NASA Astrophysics Data System (ADS)

    Grim, Gary; Casey, Daniel; Fincke, Jim; Pino, Jesse; Smalyuk, Vladimir; Steinkamp, Mike; Tipton, Robert

    2014-10-01

    Results from implosions of tritium filled plastic shells containing thin deuterated sub-layers, as well as comparisons with 1-D capsule only simulations will be reported. The implosions were directly driven using a square, 1 ns wide, 27 kJ laser pulse, provided by the Laboratory for Laser Energetics, University of Rochester, Rochester, NY. The 15 um thick, by 865 μm OD, CH capsules were fabricated with 1 μm thick, deuterated plastic layers, located either in direct contact with the tritium gas, or offset by a layer of CH. Neutrons produced by deuterium-tritium fusions signify atomic mixing between the deuterated shell and the gas payload, allowing for a detailed study of the dynamics of mix in 3-D implosions. Data has been collected on implosions from capsules with a depth of burial of 0, 1, and 2 um of CH, as well as non-deuterated control shots. Capsules were shot with two gas fill pressures, 4 and 10 atm., to provide information on mix as a function of convergence. We report nuclear and X-ray data collected from these experiments. Further, we present comparisons with, 1-D and 2-D, capsule only simulations. Prepared by LANL under Contract DE-AC-52-06-NA25396, TSPA.

  5. A measurement of the e/{pi} ratio difference between short (250 ns) and long (2.2 {mu}s) integration times with the D0 uranium-liquid argon central calorimeter

    SciTech Connect

    Pi, B.

    1992-12-31

    The difference of the ratios of the high energy electron and pion responses(e/{pi}) in the DO Uranium-liquid Argon central calorimeter is measured using the DO calorimeter trigger readout (short integration time: 250 ns) and precision readout (long integration time: 2.2 {mu}s). This measurement found a 5% difference in the e/{pi} ratio between short and long integration times, with estimated uncertainty of 2.3%.

  6. Hohlraum drive and implosion experiments on Nova. Revision 1

    SciTech Connect

    Kilkenny, J.D.; Suter, L.J.; Cable, M.D.

    1994-09-08

    Experiments on Nova have demonstrated hohlraum radiation temperatures up to 300 eV and in lower temperature experiments reproducible time integrated symmetry to 1--2%. Detailed 2-D LASNEX simulations satisfactorily reproduce Nova`s drive and symmetry scaling data bases. Hohlraums has been used for implosion experiments achieving convergence ratios (initial capsule radius/final fuel radius) up to 24 with high density glass surrounding a hot gas fill.

  7. The high-foot implosion campaign on the National Ignition Facilitya)

    NASA Astrophysics Data System (ADS)

    Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Barrios Garcia, M. A.; Hinkel, D. E.; Berzak Hopkins, L. F.; Kervin, P.; Kline, J. L.; Pape, S. Le; Ma, T.; MacPhee, A. G.; Milovich, J. L.; Moody, J.; Pak, A. E.; Patel, P. K.; Park, H.-S.; Remington, B. A.; Robey, H. F.; Salmonson, J. D.; Springer, P. T.; Tommasini, R.; Benedetti, L. R.; Caggiano, J. A.; Celliers, P.; Cerjan, C.; Dylla-Spears, R.; Edgell, D.; Edwards, M. J.; Fittinghoff, D.; Grim, G. P.; Guler, N.; Izumi, N.; Frenje, J. A.; Gatu Johnson, M.; Haan, S.; Hatarik, R.; Herrmann, H.; Khan, S.; Knauer, J.; Kozioziemski, B. J.; Kritcher, A. L.; Kyrala, G.; Maclaren, S. A.; Merrill, F. E.; Michel, P.; Ralph, J.; Ross, J. S.; Rygg, J. R.; Schneider, M. B.; Spears, B. K.; Widmann, K.; Yeamans, C. B.

    2014-05-01

    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.

  8. Investigation of regimes of wire array implosion on the 1 MA Zebra accelerator

    SciTech Connect

    Ivanov, V.V.; Kantsyrev, V.L.; Sotnikov, V.I.; Fedin, D.A.; Astanovitskiy, A. L.; Le Galloudec, B.; Nalajala, V.; Shrestha, I.; Cowan, T.E.; Jones, B.; Coverdale, C. A.; Deeney, C.; LePell, P.D.

    2006-01-15

    Implosion of wire arrays was investigated at the 1 MA Zebra accelerator by multiframe laser probing and gated x-ray self-emission diagnostics. Different regimes of implosion were observed in Al and Cu wire arrays. Implosion of Al loads with masses of 33-37 {mu}g/cm produces a dense pinch 1-1.5 mm in diameter. Strong instabilities are observed in the Z pinch at the time of stagnation. Implosion of ''overmassed'' loads produces a plasma column 3-4 mm in diameter with a core. The plasma column does not collapse during the x-ray pulse. The core of the plasma column is not subjected to the kink instability and transforms to a chain of dense spots in the later stage. Different regimes of implosion were observed in Al 8x15 {mu}m loads presumably due to variations in the current pulse and load conditions. Observed regimes are compared to three-dimensional hybrid simulation of ideal and nonideal magnetohydrodynamics modes of implosion.

  9. Investigation of regimes of wire array implosion on the 1-MA "Zebra" accelerator.

    SciTech Connect

    Sotnikov, Vladimir Isaakovich; Ivanov, Vladimir V.; Fedin, Dmitry; LePell, Paul David; Shrestha, I.; Nalajala, V.; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Deeney, Christopher; Astanovitsky, A. L.; Le Galloudec, B.; Jones, Brent Manley; Cowan, Thomas E.

    2005-06-01

    Implosion of wire arrays was investigated at the 1 MA Zebra accelerator by multiframe laser probing and gated x-ray self-emission diagnostics. Different regimes of implosion were observed in Al and Cu wire arrays. Implosion of Al loads with masses of 33-37 {micro}g/cm produces a dense pinch 1-1.5 mm in diameter. Strong instabilities are observed in the Z pinch at the time of stagnation. Implosion of 'overmassed' loads produces a plasma column 3-4 mm in diameter with a core. The plasma column does not collapse during the x-ray pulse. The core of the plasma column is not subjected to the kink instability and transforms to a chain of dense spots in the later stage. Different regimes of implosion were observed in Al 8 x 15 {micro}m loads presumably due to variations in the current pulse and load conditions. Observed regimes are compared to three-dimensional hybrid simulation of ideal and nonideal magnetohydrodynamics modes of implosion.

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

    SciTech Connect

    Hurricane, O. A. Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Barrios Garcia, M. A.; Hinkel, D. E.; Berzak Hopkins, L. F.; Kervin, P.; Pape, S. Le; Ma, T.; MacPhee, A. G.; Milovich, J. L.; Moody, J.; Pak, A. E.; Patel, P. K.; Park, H.-S.; Remington, B. A.; Robey, H. F.; and others

    2014-05-15

    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 (9.3×10{sup 15}) 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.

  11. Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

    DOE PAGESBeta

    Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; MacKinnon, A. J.; Döppner, T.; Ho, D. D.; Jones, O. S.; Khan, S. F.; Ma, T.; et al

    2015-06-02

    High Density Carbon (HDC 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 [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a 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 THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightlymore » 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 x 10¹⁵ neutrons, 40% of the 1D simulated yield.« less

  12. Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

    SciTech Connect

    Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; 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.; Izumi, N.; Kyrala, G. A.; Moody, J. D.; Patel, P. K.; Ralph, J. E.; Rygg, J. R.; Sepke, S. M.; Spears, B. K.; Tommasini, R.; Town, R. P. J.; Biener, J.; Bionta, R. M.; Bond, E. J.; Caggiano, J. A.; Eckart, M. J.; Gatu Johnson, M.; Grim, G. P.; Hamza, A. V.; Hartouni, E. P.; Hatarik, R.; Hoover, D. E.; Kilkenny, J. D.; Kozioziemski, B. J.; Kroll, J. J.; McNaney, J. M.; Nikroo, A.; Sayre, D. B.; Stadermann, M.; Wild, C.; Yoxall, B. E.; Landen, O. L.; Hsing, W. W.; Edwards, M. J.

    2015-06-02

    High Density Carbon (HDC 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 [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a 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 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 x 10¹⁵ neutrons, 40% of the 1D simulated yield.

  13. Recent Experimental Results from Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Sangster, T. C.; Goncharov, V. N.; Radha, P. B.; Betti, R.; Boehly, T. R.; Glebov, V. Yu.; Hu, S. X.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Seka, W.; Smalyuk, V. A.; Frenje, J. A.; Petrasso, R. D.; Shvarts, D.

    2008-11-01

    The implosion performance of energy-scaled cryogenic D2 and DT targets on the 60-beam OMEGA laser is important for understanding the physics of highly compressed fuel and the validation of ignition designs for the NIF. Recent experiments have demonstrated good performance using a multi-shock drive that has been tuned based on cryogenic cone-in-shell targets. Fuel areal densities are now consistently exceeding 80% of the 1-D prediction, while the yields are between 10% and 20% of 1-D predictions. These results demonstrate the benefit (and necessity) of an independent shock-timing platform. This talk will present the latest implosion performance results and potentially show the first cryogenic-fuel-core radiographs using a short pulse beam from the new OMEGA EP Laser Facility. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

  14. The evolution of instabilities during magnetically driven liner implosions.

    SciTech Connect

    Jennings, Christopher A.; Slutz, Stephen A.; Cuneo, Michael Edward; McBride, Ryan D.; Herrmann, Mark C.; Sinars, Daniel Brian

    2010-11-01

    Numerical simulations [S.A. Slutz et al Phys. Plasmas 17, 056303 (2010)] indicate that fuel magnetization and preheat could enable cylindrical liner implosions to become an efficient means to generate fusion conditions. A series of simulations has been performed to study the stability of magnetically driven liner implosions. These simulations exhibit the initial growth and saturation of an electro-thermal instability. The Rayleigh-Taylor instability further amplifies the resultant density perturbations developing a spectrum of modes initially peaked at short wavelengths. With time the spectrum of modes evolves towards longer wavelengths developing an inverse cascade. The effects of mode coupling, the radial dependence of the magnetic pressure, and the initial surface roughness will be discussed.

  15. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements.

    PubMed

    Markovic, B; Tamborini, D; Villa, F; Tisa, S; Tosi, A; Zappa, F

    2012-07-01

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB(rms). The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps(rms) (i.e., 36 ps(FWHM)) and in photon timing mode it is still better than 70 ps(FWHM). The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc. PMID:22852708

  16. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

    NASA Astrophysics Data System (ADS)

    Markovic, B.; Tamborini, D.; Villa, F.; Tisa, S.; Tosi, A.; Zappa, F.

    2012-07-01

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSBrms. The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 psrms (i.e., 36 psFWHM) and in photon timing mode it is still better than 70 psFWHM. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

  17. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

    SciTech Connect

    Markovic, B.; Tamborini, D.; Villa, F.; Tisa, S.; Tosi, A.; Zappa, F.

    2012-07-15

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB{sub rms}. The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps{sub rms} (i.e., 36 ps{sub FWHM}) and in photon timing mode it is still better than 70 ps{sub FWHM}. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

  18. Influence and measurement of mass ablation in ICF implosions

    SciTech Connect

    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.

  19. Hot spot temperature measurements in DT layered implosions

    NASA Astrophysics Data System (ADS)

    Patel, Pravesh; Ma, T.; Macphee, A.; Callahan, D.; Chen, H.; Cerjan, C.; Clark, D.; Edgell, D.; Hurricane, O.; Izumi, N.; Khan, S.; Jarrott, L.; Kritcher, A.; Springer, P.

    2015-11-01

    The temperature of the burning DT hot spot in an ICF implosion is a crucial parameter in understanding the thermodynamic conditions of the fuel at stagnation and and the performance of the implosion in terms of alpha-particle self-heating and energy balance. The continuum radiation spectrum emitted from the hot spot provides an accurate measure of the emissivity-weighted electron temperature. Absolute measurements of the emitted radiation are made with several independent instruments including spatially-resolved broadband imagers, and space- and time-integrated monochromatic detectors. We present estimates of the electron temperature in DT layered implosions derived from the radiation spectrum most consistent with the available measurements. The emissivity-weighted electron temperatures are compared to the neutron-averaged apparent ion temperatures inferred from neutron time-of-flight detectors. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Kinetic Effects at Material Interfaces in ICF Implosions

    NASA Astrophysics Data System (ADS)

    Wilks, S. C.; Cabot, W.; Whitley, H.; Greenough, J.; Cohen, B. I.; Belof, J.; Zimmerman, G.; Amendt, P. A.; Lepape, S.; Divol, L.; Dimits, A.; Graziani, F.; Molvig, K.; Dodd, E.; Li, C. K.; Petrasso, R.; Laffite, S.; Larroche, O.; Casanova, M.; Masse, L.

    2014-10-01

    The mixing of materials at an interface during an ICF implosion, for example the DT- Carbon interface in an ICF capsule, is a complex process. In general, rad-hydro codes do an excellent job of modeling the important processes during an ICF implosion. However, there are certain times during the implosion when kinetic effects of the ions may play a role in how two materials mix across the interface between them, even in the absence of shocks moving through them. The Knudsen layer effect is one such example. We will describe results of multi-ion species hybrid LSP simulations where the ions are treated kinetically and the electrons are treated as a fluid. We observe that the DT and carbon ions diffuse across the interface in a self-similar manner, at a rate proportional to the square root of time, in agreement with diffusion theory. The resulting ion distributions for each species (on both sides of the interface) will be presented, and the result of this mixing on the yield will be discussed for ICF capsules. Preliminary results of a related mixing that occurs at the gas-hohlraum wall interface will also be presented. Performed under auspices of U.S. DOE by LLNL, Contract DE-AC52-07NA27344. LLNS, LLC.

  1. An Experimental Investigation of the Implosion of Cylindrical Shell Structures

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    An experimental study of the physics of the implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and the implosions occur when the water pressure is raised above the shell buckling stability limit. High-speed photography (27,000 fps) was used to observe and measure the motion of the structure during its implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 13 positions in the tank. The cylindrical models are made from various aluminum alloys (diameter D = 39.1 mm, wall thickness t = 0.89 mm) and brass (D = 16.7 to 25.4 mm, t = 0.33 to 0.36 mm). The ends of the tubes were sealed with Aluminum caps. The pressure records are interpreted in light of the high-speed movies. Cylinder length-to-diameter (L/D) ratios between 6 and 10 were examined; in this range the cylinders implode in a mode 2 cross-sectional shape at pressures between 6.9 and 28.7 bar. It is found that the pressure versus time records from sensors placed at the same dimensionless radial position (r/D) from the cylinder surface scale well with time and pressure scales from cavitation bubble collapse theory.

  2. Optical emission spectroscopy and time-of-flight investigations of plasmas generated from AlN targets in cases of pulsed laser deposition with sub-ps and ns ultraviolet laser pulses

    NASA Astrophysics Data System (ADS)

    Ristoscu, Carmen; Mihailescu, Ion N.; Velegrakis, Michalis; Massaouti, Maria; Klini, Argyro; Fotakis, Costas

    2003-02-01

    We performed a comparative study of the plasma generated from AlN targets under sub-ps vs ns UV (λ=248 nm) excimer laser pulses. Optical emission and time-of-flight spectra recorded in cases of samples irradiated with ns laser pulses showed the presence of Al lines, which became prevalent after the first laser pulse was incident on the target. These observations are congruent with the metallization of AlN targets inside each crater under multipulse ns laser action at laser fluences above the ablation threshold, observed by visual inspection and optical microscopy. Metallization was not observed when working with sub-ps laser pulses. Moreover, our studies confirmed the predominant presence of AlN positive molecular ions in the plasma generated in front of AlN targets submitted to sub-ps multipulse laser irradiation. The optical emission data are in good agreement with time-of-flight mass analysis. We emphasize that all investigations support the experimental evidence reported by György et al. [E. György et al., J. Appl. Phys. 90, 456 (2001)], according to which thin films obtained by pulsed laser deposition with ns laser pulses contain a significant amount of metallic Al, while only AlN is detected in films obtained with sub-ps laser pulses. Measurements of the velocity and kinetic energy distributions of AlN+ indicate that in the case of ns-laser ablation the ions are emitted with thermal energy, while in the case of sub-ps-laser ablation a bimodal distribution exists and has thermal (1 eV) and hyperthermal (10 eV) energy components. This points to different plasma formation mechanisms for the two cases.

  3. Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments

    NASA Astrophysics Data System (ADS)

    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. Realization of quasi-spherical implosion using pre-shaped prolate wire arrays with a compression foam target inside

    SciTech Connect

    Zhang, Yang; Ding, Ning; Xiao, Delong; Sun, Shunkai; Xue, Chuang; Shu, Xiaojian; Wang, Jianguo; Li, Zhenghong Xu, Rongkun; Chen, Dingyang; Ye, Fan; Chen, Faxin; Chen, Jinchuan; Li, Linbo; Zhou, Xiuwen

    2015-02-15

    Quasi-spherical (QS) implosion of wire arrays and its impact on the foam target have been studied on the 100 ns 1.5 MA Qiangguang-I facility, which suggests that a high quality impact between the QS implosion and foam target can be achieved by adjusting load's initial shape carefully to match the external magnetic pressure. Implosions of loads with H/d ∼ 1.2 were studied with a self-emission x-ray pinhole image system and a dark field schlieren system. The radially developed spike-like instabilities indicate the spherical convergence of plasma. The observed radiation on the foam target surface suggests satisfying implosion symmetry and wire-foam impact simultaneity. An average implosion speed of 10.5 × 10{sup 6 }cm/s was obtained with an optical streak image system. The derived peak kinetic energy density ∼2.1 kJ/cm is remarkably higher than cylindrical cases, which agree with the expectations.

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

    NASA Astrophysics Data System (ADS)

    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. Implosion Source Development and Diego Garcia Reflections

    SciTech Connect

    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

  7. Cleavage of the dengue virus polyprotein at the NS3/NS4A and NS4B/NS5 junctions is mediated by viral protease NS2B-NS3, whereas NS4A/NS4B may be processed by a cellular protease.

    PubMed Central

    Cahour, A; Falgout, B; Lai, C J

    1992-01-01

    The cleavage mechanism utilized for processing of the NS3-NS4A-NS4B-NS5 domain of the dengue virus polyprotein was studied by using the vaccinia virus expression system. Recombinant vaccinia viruses vNS2B-NS3-NS4A-NS4B-NS5, vNS3-NS4A-NS4B-NS5, vNS4A-NS4B-NS5, and vNS4B-NS5 were constructed. These recombinants were used to infect cells, and the labeled lysates were analyzed by immunoprecipitation. Recombinant vNS2B-NS3-NS4A-NS4B-NS5 expressed the authentic NS3 and NS5 proteins, but the other recombinants produced uncleaved polyproteins. These findings indicate that NS2B is required for processing of the downstream nonstructural proteins, including the NS3/NS4A and NS4B/NS5 junctions, both of which contain a dibasic amino acid sequence preceding the cleavage site. The flavivirus NS4A/NS4B cleavage site follows a long hydrophobic sequence. The polyprotein NS4A-NS4B-NS5 was cleaved at the NS4A/NS4B junction in the absence of other dengue virus functions. One interpretation for this finding is that NS4A/NS4B cleavage is mediated by a host protease, presumably a signal peptidase. Although vNS3-NS4A-NS4B-NS5 expressed only the polyprotein, earlier results demonstrated that cleavage at the NS4A/NS4B junction occurred when an analogous recombinant, vNS3-NS4A-84%NS4B, was expressed. Thus, it appears that uncleaved NS3 plus NS5 inhibit NS4A/NS4B cleavage presumably because the putative signal sequence is not accessible for recognition by the responsible protease. Finally, recombinants that expressed an uncleaved NS4B-NS5 polyprotein, such as vNS4A-NS4B-NS5 or vNS4B-NS5, produced NS5 when complemented with vNS2B-30%NS3 or with vNS2B plus v30%NS3. These results indicate that cleavage at the NS4B/NS5 junction can be mediated by NS2B and NS3 in trans. Images PMID:1531368

  8. The High-Foot Implosion Campaign on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Hurricane, Omar

    2013-10-01

    The `High-Foot' platform manipulates the laser pulse-shape coming from the National Ignition Facility (NIF) 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 tactic 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. This approach is generally consistent with the philosophy laid out in a recent international workshop on the topic of ignition science on NIF [``Workshop on the Science of Fusion Ignition on NIF,'' Lawrence Livermore National Laboratory Report, LLNL-TR-570412 (2012). Op cit. V. Gocharov and O.A. Hurricane, ``Panel 3 Report: Implosion Hydrodynamics,'' LLNL-TR-562104 (2012)]. Side benefits our the High-Foot pulse-shape modification appear to be improvements in hohlraum behavior--less wall motion achieved through higher pressure He gas fill and improved inner cone laser beam propagation. Another consequence of the `High-Foot' is a higher fuel adiabat, so there is some relation to direct-drive experiments performed at the Laboratory for Laser Energetics (LLE). In this talk, 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. Most notably, at the time of this writing record DT layer implosion performance with record low levels of inferred mix and excellent agreement with one-dimensional implosion models without the aid of mix models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Implosive Therapy Treatment of Heroin Addicts during Methadone Detoxification.

    ERIC Educational Resources Information Center

    Hirt, Michael; Greenfield, Heywood

    1979-01-01

    Examined effectiveness of implosive therapy with heroin addicts during detoxification from methadone. Treatment groups received 12 sessions of implosive therapy or eclectic counseling and were followed for a six-week period. The implosive therapy group were the only ones to significantly reduce their methadone level during treatment and follow-up.…

  10. Gas-puff liner implosion in the configuration with helical current return rods

    SciTech Connect

    Sorokin, S. A.

    2013-02-15

    Results of experiments with double-shell gas-puff liners carried out on a high-current MIG generator (2 MA, 80 ns) are presented. To stabilize the process of liner implosion and increase the efficiency of energy transfer from the generator to the liner plasma, a current return in the form of a multifilar helix was used. The effect of the configuration of the current return on the parameters of the generated pulses of argon and neon K-shell radiation (with photon energies of 3-5 and 0.9-1.5 keV, respectively) and the neutron yield from a deuterium liner were studied.

  11. X-ray imaging measurements of capsule implosions driven by a Z-pinch dynamic hohlraum.

    PubMed

    Bailey, J E; Chandler, G A; Slutz, S A; Bennett, G R; Cooper, G; Lash, J S; Lazier, S; Lemke, R; Nash, T J; Nielsen, D S; Moore, T C; Ruiz, C L; Schroen, D G; Smelser, R; Torres, J; Vesey, R A

    2002-08-26

    The radiation and shock generated by impact of an annular tungsten Z-pinch plasma on a 10-mm diam 5-mg/cc CH(2) foam are diagnosed with x-ray imaging and power measurements. The radiative shock was virtually unaffected by Z-pinch plasma instabilities. The 5-ns-duration approximately 135-eV radiation field imploded a 2.1-mm-diam CH capsule. The measured radiation temperature, shock radius, and capsule radius agreed well with computer simulations, indicating understanding of the main features of a Z-pinch dynamic-hohlraum-driven capsule implosion. PMID:12190409

  12. The first capsule implosion experiments on Orion

    NASA Astrophysics Data System (ADS)

    Garbett, W. J.; Horsfield, C. J.; Gales, S. G.; Leatherland, A. E.; Rubery, M. S.; Coltman, J. E.; Meadowcroft, A. E.; Rice, S. J.; Simons, A. J.; Woolhead, V. E.

    2016-05-01

    Direct drive capsule implosions are being developed on the Orion laser at AWE as a platform for ICF and HED physics experiments. The Orion facility combines both long pulse and short-pulse beams, making it well suited for studying the physics of alternative ignition approaches. Orion implosions also provide the opportunity to study aspects of polar direct drive. Limitations on drive symmetry from the relatively small number of laser beams makes predictive modelling of the implosions challenging, resulting in some uncertainty in the expected capsule performance. Initial experiments have been fielded to evaluate baseline capsule performance and inform future design optimization. Highly promising DD fusion neutron yields in excess of 109 have been recorded. Results from the experiments are presented alongside radiation-hydrocode modelling.

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

    PubMed

    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. PMID:23126937

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

    SciTech Connect

    Ma, T.; Izumi, N.; Tommasini, R.; Bradley, D. K.; Bell, P.; Cerjan, C. J.; Dixit, S.; Doeppner, T.; Jones, O.; Landen, O. L.; LePape, S.; Mackinnon, A. J.; Park, H.-S.; Patel, P. K.; Prasad, R. R.; Ralph, J.; Smalyuk, V. A.; Springer, P. T.; Suter, L.; Town, R. P. J.; and others

    2012-10-15

    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.

  15. Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

    NASA Astrophysics Data System (ADS)

    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.; McKenty, P. W.; Hohenberger, M.; Radha, P. B.; Delettrez, J. A.; Glebov, V. Yu.; Betti, R.; Goncharov, V. N.; Knauer, J. P.; Sangster, T. C.; LePape, S.; Mackinnon, A. J.; Pino, J.; McNaney, J. M.; 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.; Ma, T.; MacPhee, A.; Meezan, N. B.; Moody, J. D.; Moran, M. J.; Park, H.-S.; Remington, B. A.; Robey, H.; Rosen, M. D.; Wilks, S. C.; Zacharias, R. A.; Herrmann, H. W.; Hoffman, N. M.; Kyrala, G. A.; Leeper, R. J.; Olson, R. E.; Kilkenny, J. D.; Nikroo, A.

    2014-12-01

    Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D2 and D3He gas-filled "exploding-pusher" inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to the predictions of 2D draco hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.

  16. Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

    SciTech Connect

    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.; McKenty, P. W.; Hohenberger, M.; Radha, P. B.; Delettrez, J. A.; Glebov, V. Yu.; Betti, R.; Goncharov, V. N.; Knauer, J. P.; Sangster, T. C.; and others

    2014-12-15

    Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D{sub 2} and D{sup 3}He gas-filled “exploding-pusher” inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to the predictions of 2D DRACO hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.

  17. Neutron spectrometry--an essential tool for diagnosing implosions at the National Ignition Facility (invited).

    PubMed

    Gatu Johnson, M; Frenje, J A; Casey, D T; Li, C K; Séguin, F H; Petrasso, R; Ashabranner, R; Bionta, R M; Bleuel, D L; Bond, E J; Caggiano, J A; Carpenter, A; Cerjan, C J; Clancy, T J; Doeppner, T; Eckart, M J; Edwards, M J; Friedrich, S; Glenzer, S H; Haan, S W; Hartouni, E P; Hatarik, R; Hatchett, S P; Jones, O S; Kyrala, G; Le Pape, S; Lerche, R A; Landen, O L; Ma, T; MacKinnon, A J; McKernan, M A; Moran, M J; Moses, E; Munro, D H; McNaney, J; Park, H S; Ralph, J; Remington, B; Rygg, J R; Sepke, S M; Smalyuk, V; Spears, B; Springer, P T; Yeamans, C B; Farrell, M; Jasion, D; Kilkenny, J D; Nikroo, A; Paguio, R; Knauer, J P; Glebov, V Yu; Sangster, T C; Betti, R; Stoeckl, C; Magoon, J; Shoup, M J; Grim, G P; Kline, J; Morgan, G L; Murphy, T J; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A J

    2012-10-01

    DT neutron yield (Y(n)), ion temperature (T(i)), and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of inertial confinement fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-time-of-flight (nTOF) spectrometers and a magnetic recoil spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the complementarity required for reliable measurements of Y(n), T(i), and dsr. From the measured dsr value, an areal density (ρR) is determined through the relationship ρR(tot) (g∕cm(2)) = (20.4 ± 0.6) × dsr(10-12 MeV). The proportionality constant is determined considering implosion geometry, neutron attenuation, and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration of the as-built spectrometers, which are now performing to the required accuracy. Recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental ignition threshold factor (ITFx), which is a function of dsr (or fuel ρR) and Y(n), has improved almost two orders of magnitude since the first shot in September, 2010. PMID:23126835

  18. Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility

    SciTech Connect

    Mackinnon, A J; Johnson, M G; Frenje, J A; Casey, D T; Li, C K; Seguin, F H; Petrasso, R; Ashabranner, R; Cerjan, C; Clancy, T J; Bionta, R; Bleuel, D; Bond, E J; Caggiano, J A; Capenter, A; Eckart, M J; Edwards, M J; Friedrich, S; Glenzer, S H; Haan, S W; Hartouni, E P; Hatarik, R; Hachett, S P; McKernan, M; Jones, O; Lepape, S; Lerche, R A; Landen, O L; Moran, M; Moses, E; Munro, D; McNaney, J; Rygg, J R; Sepke, S; Spears, B; Springer, P; Yeamans, C; Farrell, M; Kilkenny, J D; Nikroo, A; Paguio, R; Knauer, J; Glebov, V; Sangster, T; Betti, R; Stoeckl, C; Magoon, J; Shoup, M J; Grim, G P; Moran, G L; Murphy, T J; Leeper, R J; Ruiz, C

    2012-05-02

    DT neutron yield (Y{sub n}), ion temperature (T{sub i}) and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-Time-Of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the redundancy required for reliable measurements of Yn, Ti and dsr. From the measured dsr value, an areal density ({rho}R) is determined from the relationship {rho}R{sub tot} (g/cm{sup 2}) = (20.4 {+-} 0.6) x dsr{sub 10-12 MeV}. The proportionality constant is determined considering implosion geometry, neutron attenuation and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration. The spectrometers are now performing to the required accuracy, as indicated by the good agreement between the different measurements over several commissioning shots. In addition, recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental Ignition Threshold Factor (ITFx) which is a function of dsr (or fuel {rho}R) and Y{sub n}, has improved almost two orders of magnitude since the first shot in September, 2010.

  19. X-ray backlit imaging measurement of in-flight pusher density for an indirect drive capsule implosion

    SciTech Connect

    Kalantar, D.H.; Haan, S.W.; Hammel, B.A.

    1996-05-06

    Both the efficiency of an implosion and the growth rate of hydrodynamic instability increase with the aspect ratio of an implosion. In order to study the physics of implosions with high Rayleigh-Taylor growth factors, we use doped ablators which should minimize x-ray preheat and shell decompression, and hence increase in-flight aspect ratio. We use x-ray backlighting techniques to image the indirectly-driven capsules. We record backlit 4.7 keV images of the full capsule throughout the implosion phase with 55 ps and 15 {mu}m resolution. We use these images to measure the in-flight aspect ratios for doped ablators, and we inferred the radial density profile as a function of time by Abel inverting the x-ray transmission profiles.

  20. Correlations of Multiple Ion-Temperature Measurements with Shot Parameters in DT Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Glebov, V. Yu.; Forrest, C. J.; Sangster, T. C.; Stoeckl, C.

    2014-10-01

    Several neutron time-of-flight (nTOF) detectors installed at different lines of sight (LOS) are used to measure neutron-averaged ion temperature in direct-drive DT implosions on the OMEGA laser. The measurement precision of the ion temperature in different LOS for ambient targets is less than 4% rms. In DT cryogenic implosions, however, the ratio of the ion temperature measured in different LOS can vary by a factor of 2. Correlations of the ion-temperature difference with parameters such as target offset, beam power balance, and phase plates in DT cryogenic implosions on OMEGA will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

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

    SciTech Connect

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

    2014-12-15

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Diagnosing residual motion via the x-ray self emission from indirectly driven inertial confinement implosions

    SciTech Connect

    Pak, A. Field, J. E.; Benedetti, L. R.; Caggiano, J.; Hatarik, R.; Izumi, N.; Khan, S. F.; Ma, T.; Spears, B. K.; Town, R. P. J.; Bradley, D. K.; Knauer, J.

    2014-11-15

    In an indirectly driven implosion, non-radial translational motion of the compressed fusion capsule is a signature of residual kinetic energy not coupled into the compressional heating of the target. A reduction in compression reduces the peak pressure and nuclear performance of the implosion. Measuring and reducing the residual motion of the implosion is therefore necessary to improve performance and isolate other effects that degrade performance. Using the gated x-ray diagnostic, the x-ray Bremsstrahlung emission from the compressed capsule is spatially and temporally resolved at x-ray energies of >8.7 keV, allowing for measurements of the residual velocity. Here details of the x-ray velocity measurement and fitting routine will be discussed and measurements will be compared to the velocities inferred from the neutron time of flight detectors.

  4. Diagnosing residual motion via the x-ray self emission from indirectly driven inertial confinement implosions.

    PubMed

    Pak, A; Field, J E; Benedetti, L R; Caggiano, J; Hatarik, R; Izumi, N; Khan, S F; Knauer, J; Ma, T; Spears, B K; Town, R P J; Bradley, D K

    2014-11-01

    In an indirectly driven implosion, non-radial translational motion of the compressed fusion capsule is a signature of residual kinetic energy not coupled into the compressional heating of the target. A reduction in compression reduces the peak pressure and nuclear performance of the implosion. Measuring and reducing the residual motion of the implosion is therefore necessary to improve performance and isolate other effects that degrade performance. Using the gated x-ray diagnostic, the x-ray Bremsstrahlung emission from the compressed capsule is spatially and temporally resolved at x-ray energies of >8.7 keV, allowing for measurements of the residual velocity. Here details of the x-ray velocity measurement and fitting routine will be discussed and measurements will be compared to the velocities inferred from the neutron time of flight detectors. PMID:25430351

  5. NS-NS sector of closed superstring field theory

    NASA Astrophysics Data System (ADS)

    Erler, Theodore; Konopka, Sebastian; Sachs, Ivo

    2014-08-01

    We give a construction for a general class of vertices in superstring field theory which include integration over bosonic moduli as well as the required picture changing insertions. We apply this procedure to find a covariant action for the NS-NS sector of Type II closed superstring field theory.

  6. Gas Puff Z-Pinches at 1-MA and 200-ns on COBRA

    NASA Astrophysics Data System (ADS)

    Hammer, David; Qi, Niansheng; Rosenberg, Elliott; Atoyan, Levon; Potter, William; Blesener, Kate; Cahill, Adam; Gourdain, Pierre-Alexandre; Greenly, John; Hoyt, Cad; Kusse, Bruce; Pikuz, Sergei; Schrafel, Peter; Shelkovenko, Tatiana

    2013-10-01

    We report 6-cm diameter, double-shell gas puff Z-pinch experiments at 1 MA on the COBRA pulsed power generator, in which the implosion dynamics in puff-on-puff load configurations with and without a wire on the pinch axis were studied. Diagnostics used included: Planar Laser Induced Fluorescence Analyzer for measuring initial density profiles of the gas puff; a Laser Shearing Interferometer and a Laser Wavefront Analyzer for density profiles in the implosion and pinch phases; fiber-coupled, gated visible-light spectrometers for radially resolved imploding plasma spectra; gated XUV cameras for implosion dynamics; filtered pinhole x-ray cameras for imaging x-ray emission; and a double-crystal x-ray spectrometer for axially resolved pinch plasma densities and temperatures. From these, we derived the implosion velocity, ion charge states and then the imploding plasma temperatures, obtained the time evolution of the imploding plasma sheath structure and Magnetic Rayleigh-Taylor instability, and observed the most stable implosion with light-ions (Ne) imploding on heavy-ions (Ar), unstable implosions with heavy-ions (Ar) imploding on light-ions (Ne), and tighter, denser and less hot pinch plasma with a wire on axis. Details of the results will be presented. Supported by NNSA under DOE Coop. Agreement DE- NA0001836.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Nuclear diagnostics for inertial confinement fusion implosions

    SciTech Connect

    Murphy, T.J.

    1997-11-01

    This abstract contains viewgraphs on nuclear diagnostic techniques for inertial confinement fusion implosions. The viewgraphs contain information on: reactions of interest in ICF; advantages and disadvantages of these methods; the properties nuclear techniques can measure; and some specifics on the detectors used.

  9. Implosive Therapy as a Treatment for Insomnia.

    ERIC Educational Resources Information Center

    Carrera, Richard N.; Elenewski, Jeffrey J.

    1980-01-01

    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 subjects' anxiety-based reluctance to acknowledge openly such fear. (Author)

  10. Implosive therapy as a treatment for insomnia.

    PubMed

    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

  11. Enhanced energy coupling and x-ray emission in Z-pinch plasma implosions

    NASA Astrophysics Data System (ADS)

    Whitney, K. G.; Thornhill, J. W.; Apruzese, J. P.; Davis, J.; Deeney, C.; Coverdale, C. A.

    2004-08-01

    Recent experiments conducted on the Saturn pulsed-power generator at Sandia National Laboratories [R. B. Spielman et al., in Proceedings of the Second International Conference on Dense Z Pinches, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] have produced large amounts of x-ray output, which cannot be accounted for in conventional magnetohydrodynamic (MHD) calculations. In these experiments, the Saturn current had a rise time of ~180 ns in contrast to a rise time of ~60 ns in Saturn's earlier mode of operation. In both aluminum and tungsten wire-array Z-pinch implosions, 2-4 times more x-ray output was generated than could be supplied according to one-dimensional (1D) magnetohydrodynamic calculations by the combined action of the j×B acceleration forces and ohmic heating (as described by a classical Braginskii resistivity). In this paper, we reexamine the problem of coupling transmission line circuits to plasma fluid equations and derive expressions for the Z-pinch load circuit resistance and inductance that relate these quantities in a 1D analysis to the surface resistivity of the fluid, and to the magnetic field energy that is stored in the vacuum diode, respectively. Enhanced energy coupling in this analysis, therefore, comes from enhancements to the surface resistivity, and we show that plasma resistivities approximately three orders of magnitude larger than classical are needed in order to achieve energy inputs that are comparable to the Saturn experiment x-ray outputs. Large enhancements of the plasma resistivity increase the rate of magnetic field and current diffusion, significantly modify the qualitative features of the MHD, and raise important questions as to how the plasma fluid dynamics converts enhanced energy inputs into enhanced x-ray outputs. One-dimensional MHD calculations in which resistivity values are adjusted phenomenologically are used to illustrate how

  12. Deceleration Phase of Inertial Confinement Fusion Implosions

    NASA Astrophysics Data System (ADS)

    Betti, R.

    2001-10-01

    In inertial confinement fusion (ICF) implosions, a spherical shell of cryogenic deuterium and tritium (DT) filled with DT gas is accelerated by direct laser irradiation (direct drive) or x-rays produced by a high-Z enclosure (indirect drive). Hydrodynamic instabilities, growing on the outer shell surface during the acceleration phase, cause the outer nonuniformities to feed through the shell onto the inner surface. As the shell starts to decelerate, the inner surface is unstable to the Rayleigh-Taylor instability and the inner surface nonuniformities grow exponentially in time, causing the cold shell material to penetrate and cool the hot spot. Such a cooling could prevent the hot spot from achieving the ignition conditions. We have developed a model to study the deceleration phase of imploding capsules, including the onset of ignition. The model yields all the hot-spot profiles and the hydrodynamic parameters of interest to the deceleration phase instability: ablation velocity [Ref.1] off the shell's inner surface, density-gradient scale length, and deceleration. It is shown [Ref. 1] that the growth rates of the deceleration-phase instability are significantly reduced by the finite ablative flow and the unstable spectrum exhibits a cutoff at short wavelengths. For a direct-drive NIF-like capsule, the cutoff mode number occurs for l ~= 90. The marginal ignition scaling law of Ref. 2 is also recovered analytically. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460. [1] V. Lobatchev and R. Betti, Phys. Rev. Lett. 85, 4522 (2000); [2] M. C. Herrmann, M. Tabak, and J. D. Lindl, Nucl. Fusion 41, 99 (2001).

  13. Implosive accretion and outbursts of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Lovelace, R. V. E.; Romanova, M. M.; Newman, W. I.

    1994-01-01

    A model and simulation code have been developed for time-dependent axisymmetric disk accretion onto a compact object including for the first time the influence of an ordered magnetic field. The accretion rate and radiative luminosity of the disk are naturally coupled to the rate of outflow of energy and angular momentum in magnetically driven (+/- z) winds. The magnetic field of the wind is treated in a phenomenological way suggested by self-consistent wind solutions. The radial accretion speed u(r, t) of the disk matter is shown to be the sum of the usual viscous contribution and a magnetic contribution proportional to r(exp 3/2)(B(sub p exp 2))/sigma, where B(sub p)(r,t) is the poloidal field threading the disk and sigma(r,t) is the disk's surface mass density. An enhancement or variation in B(sub p) at a large radial distance leads to the formation of a soliton-like structure in the disk density, temperature, and B-field which propagates implosively inward. The implosion gives a burst in the power output in winds or jets and a simultaneous burst in the disk radiation. The model is pertinent to the formation of discrete fast-moving components in jets observed by very long baseline interferometry. These components appear to originate at times of optical outbursts of the active galactic nucleus.

  14. Modifying Wire Array Z-pinch Ablation Structure and Implosion Dynamics Using Coiled Arrays

    SciTech Connect

    Hall, Gareth N.; Bland, Simon N.; Lebedev, Sergey V.; Chittenden, Jeremy P.; Palmer, James B. A.; Suzuki-Vidal, Francisco A.; Swadling, George F.; Niasse, Nicolas; Knapp, P. F.; Blesener, I. C.; McBride, R. D.; Chalenski, D. A.; Bell, K. S.; Greenly, J. B.; Blanchard, T.; Wilhelm, H.; Hammer, D. A.; Kusse, B. R.; Bott, Simon C.

    2009-01-21

    Coiled arrays, a cylindrical array in which each wire is formed into a helix, suppress the modulation of ablation at the fundamental wavelength. Outside the vicinity of the wire cores, ablation flow from coiled arrays is modulated at the coil wavelength and has a 2-stream structure in the r,{theta} plane. Within the vicinity of the helical wires, ablation is concentrated at positions with the greatest azimuthal displacement and plasma is axially transported from these positions such that the streams become aligned with sections of the coil furthest from the array axis. The GORGON MHD code accurately reproduces this observed ablation structure, which can be understood in terms of JxB forces that result from the interaction of the global magnetic field with a helical current path as well as additional current paths suggested by the simulations. With this ability to control where ablation streamers occur, large wavelength coils were constructed such that the breaks that form in the wires had sufficient axial separation to prevent perturbations in the implosion sheath from merging. This produces a new mode of implosion in which the global instability can be controlled and perturbations correlated between all wires in an array. For large wavelength 8-wire coiled arrays, this produced a dramatic increase in x-ray power, equalling that of a 32-wire straight array. These experiments were carried out on the MAGPIE generator (1 MA, 240 ns) at Imperial College, and the COBRA generator (1 MA, 100 ns) at Cornell University.

  15. Beryllium liner implosion experiments on the Z accelerator in preparation for magnetized liner inertial fusiona)

    NASA Astrophysics Data System (ADS)

    McBride, R. D.; Martin, M. R.; Lemke, R. W.; Greenly, J. B.; Jennings, C. A.; Rovang, D. C.; Sinars, D. B.; Cuneo, M. E.; Herrmann, M. C.; Slutz, S. A.; Nakhleh, C. W.; Ryutov, D. D.; Davis, J.-P.; Flicker, D. G.; Blue, B. E.; Tomlinson, K.; Schroen, D.; Stamm, R. M.; Smith, G. E.; Moore, J. K.; Rogers, T. J.; Robertson, G. K.; Kamm, R. J.; Smith, I. C.; Savage, M.; Stygar, W. A.; Rochau, G. A.; Jones, M.; Lopez, M. R.; Porter, J. L.; Matzen, M. K.

    2013-05-01

    Multiple experimental campaigns have been executed to study the implosions of initially solid beryllium (Be) liners (tubes) on the Z pulsed-power accelerator. The implosions were driven by current pulses that rose from 0 to 20 MA in either 100 or 200 ns (200 ns for pulse shaping experiments). These studies were conducted in support of the recently proposed Magnetized Liner Inertial Fusion concept [Slutz et al., Phys. Plasmas 17, 056303 (2010)], as well as for exploring novel equation-of-state measurement techniques. The experiments used thick-walled liners that had an aspect ratio (initial outer radius divided by initial wall thickness) of either 3.2, 4, or 6. From these studies, we present three new primary results. First, we present radiographic images of imploding Be liners, where each liner contained a thin aluminum sleeve for enhancing the contrast and visibility of the liner's inner surface in the images. These images allow us to assess the stability of the liner's inner surface more accurately and more directly than was previously possible. Second, we present radiographic images taken early in the implosion (prior to any motion of the liner's inner surface) of a shockwave propagating radially inward through the liner wall. Radial mass density profiles from these shock compression experiments are contrasted with profiles from experiments where the Z accelerator's pulse shaping capabilities were used to achieve shockless ("quasi-isentropic") liner compression. Third, we present "micro-Ḃ" measurements of azimuthal magnetic field penetration into the initially vacuum-filled interior of a shocked liner. Our measurements and simulations reveal that the penetration commences shortly after the shockwave breaks out from the liner's inner surface. The field then accelerates this low-density "precursor" plasma to the axis of symmetry.

  16. Beryllium liner implosion experiments on the Z accelerator in preparation for magnetized liner inertial fusion

    SciTech Connect

    McBride, R. D.; Martin, M. R.; Lemke, R. W.; Jennings, C. A.; Rovang, D. C.; Sinars, D. B.; Cuneo, M. E.; Herrmann, M. C.; Slutz, S. A.; Nakhleh, C. W.; Davis, J.-P.; Flicker, D. G.; Rogers, T. J.; Robertson, G. K.; Kamm, R. J.; Smith, I. C.; Savage, M.; Stygar, W. A.; Rochau, G. A.; Jones, M.; and others

    2013-05-15

    Multiple experimental campaigns have been executed to study the implosions of initially solid beryllium (Be) liners (tubes) on the Z pulsed-power accelerator. The implosions were driven by current pulses that rose from 0 to 20 MA in either 100 or 200 ns (200 ns for pulse shaping experiments). These studies were conducted in support of the recently proposed Magnetized Liner Inertial Fusion concept [Slutz et al., Phys. Plasmas 17, 056303 (2010)], as well as for exploring novel equation-of-state measurement techniques. The experiments used thick-walled liners that had an aspect ratio (initial outer radius divided by initial wall thickness) of either 3.2, 4, or 6. From these studies, we present three new primary results. First, we present radiographic images of imploding Be liners, where each liner contained a thin aluminum sleeve for enhancing the contrast and visibility of the liner's inner surface in the images. These images allow us to assess the stability of the liner's inner surface more accurately and more directly than was previously possible. Second, we present radiographic images taken early in the implosion (prior to any motion of the liner's inner surface) of a shockwave propagating radially inward through the liner wall. Radial mass density profiles from these shock compression experiments are contrasted with profiles from experiments where the Z accelerator's pulse shaping capabilities were used to achieve shockless (“quasi-isentropic”) liner compression. Third, we present “micro-B-dot ” measurements of azimuthal magnetic field penetration into the initially vacuum-filled interior of a shocked liner. Our measurements and simulations reveal that the penetration commences shortly after the shockwave breaks out from the liner's inner surface. The field then accelerates this low-density “precursor” plasma to the axis of symmetry.

  17. Performance of high-density-carbon (HDC) ablator implosion experiments on the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    MacKinnon, Andy

    2013-10-01

    A series of experiments on the National Ignition Facility (NIF) have been performed to measure high-density carbon (HDC) ablator performance for indirect drive inertial confinement fusion (ICF). HDC is a very promising ablator material; being 3x denser than plastic, it absorbs more hohlraum x-rays, leading to higher implosion efficiency. For the HDC experiments the NIF laser generated shaped laser pulses with peak power up to 410 TW and total energy of 1.3 MJ. Pulse shapes were designed to drive 2, 3 or 4 shocks in cryogenic layered implosions. The 2-shock pulse, with a designed fuel adiabat of ~3 is 6-7ns in duration, allowing use of near vacuum hohlraums, which greatly increases the coupling efficiency due to low backscatter losses. Excellent results were obtained for 2,3 and 4 shock pulses. In particular a deuterium-tritium gas filled HDC capsule driven by a 4-shock pulse in a gas-filled hohlraum produced a neutron yield of 1.6 × 1015, a record for a non-cryogenically layered capsule driven by a gas-filled hohlraum. The first 2-shock experiment used a vacuum hohlraum to drive a DD gas filled HDC capsule with a 6.5 ns, laser pulse. This hohlraum was 40% more efficient than the gas-filled counterpart used for 3 and 4 shock experiments, producing near 1D performance at 11 x convergence ratio, peak radiation temperature of 317 eV, 98% laser-hohlraum coupling, and DD neutron yield of 2.2e13, a record for a laser driven DD implosion. The HDC campaigns will be presented, including options for pushing towards the alpha dominated regime. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Dynamic hohlraum and ICF pellet implosion experiments on Z

    SciTech Connect

    Nash, T.J.; Derzon, M.S.; Chandler, G.A.

    1999-07-01

    By stabilizing an imploding z-pinch on Z (20 MA, 100 ns) with a solid current return can and a nested wire array the authors have achieved dynamic hohlraum radiation temperatures over 200 eV at a diameter of approximately 1 mm. The pinch configuration yielding this temperature is a nested tungsten wire array of 240 and 120 wires at 4 and 2 cm diameters weighing 2 and 1 mg, 1 cm long, imploding onto a 5 mm diameter, 14 mg/cc cylindrical CH foam, weighing 3 mg. They have used a single 4 cm diameter tungsten wire array to drive a 1.6 mm diameter ICF capsule mounted in a 6 mg/cc foam inside a 3 mg copper annulus at 5 mm diameter, and measured x-ray emissions indicative of the pellet implosion. Mounting the pellet in foam may have caused the hohlraum to become equator-hot. They will present results from upcoming pellet experiments in which the pellet is mounted by thread and driven by a larger diameter, 6 or 7 mm, copper annulus to improve radiation drive symmetry. They will also discuss designs for tapered foam annular targets that distort a cylindrical pinch into a quasi-sphere that will wrap around an ICF pellet to further improve drive symmetry.

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

    SciTech Connect

    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.; Deeney, Christopher E.; Douglas, Melissa R.; Chittenden, Jerry

    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.

  1. Triple-picket warm plastic-shell implosions on OMEGA

    SciTech Connect

    Radha, P. B.; Stoeckl, C.; Goncharov, V. N.; Delettrez, J. A.; Edgell, D. H.; Igumenshchev, I. V.; Knauer, J. P.; Marozas, J. A.; Regan, S. P.; Sangster, T. C.; Seka, W.; Skupsky, S.; Frenje, J. A.; McCrory, R. L.; Meyerhofer, D. D.; Petrasso, R. D.

    2011-01-15

    Warm deuterium-gas-filled plastic shells are imploded by direct irradiation from the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The pulse shapes contain three pickets that precede a sharp rise to a constant laser intensity at {approx}4.5x10{sup 14} W/cm{sup 2}. The in-flight-aspect-ratio (IFAR), a crucial measure of shell instability to nonuniformity growth, is varied in these implosions by changing picket energies and the timing among the pickets. Simulations that include cross-beam energy transfer in addition to inverse bremsstrahlung for the laser-energy deposition models show better agreement with measurements of the neutron bang time and temporally resolved scattered light and therefore more correctly model the shell kinetic energy. It is also shown that target performance improves significantly as IFAR is reduced. Nearly twice the neutron yield is measured for IFAR{approx}31 compared to IFAR{approx}60. The ratio of the measured to simulated neutron yield and areal density increases significantly with decreasing IFAR. These implosions unambiguously link target performance to in-flight shell instability attributable to short-wavelength growth and indicate that IFAR{<=}40 is required to achieve adequate compression at this intensity.

  2. Triple-Picket Warm Plastic-Shell Implosions on OMEGA

    SciTech Connect

    Stoeckl, C; Goncharov, V N; Delettrez, J A; Edgell, D H; Frenje, J A; Igumenshchev, I V; Knauer, J P; Marozas, J A; McCrory, R L; Meyerhofer, D D; Petrasso, R D; Regan, S P; Sangster, T C; Seka, W

    2011-02-09

    Warm deuterium-gas-filled plastic shells are imploded by direct irradiation from the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The pulse shapes contain three pickets that precede a sharp rise to a constant laser intensity at ~4.5 x 10^14 W/cm^2. The in-flight-aspect-ratio (IFAR), a crucial measure of shell instability to nonuniformity growth, is varied in these implosions by changing picket energies and the timing among the pickets. Simulations that include cross-beam energy transfer in addition to inverse bremsstrahlung for the laser-energy deposition models show better agreement with measurements of the neutron bang time and temporally resolved scattered light and therefore more correctly model the shell kinetic energy. It is also shown that target performance improves significantly as IFAR is reduced. Nearly twice the neutron yield is measured for IFAR ~ 31 compared to IFAR ~ 60. The ratio of the measured to simulated neutron yield and areal density increases significantly with decreasing IFAR. These implosions unambiguously link target performance to in-flight shell instability attributable to short-wavelength growth and indicate that IFAR ~ 40 is required to achieve adequate compression at this intensity.

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

    NASA Astrophysics Data System (ADS)

    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).

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

    NASA Astrophysics Data System (ADS)

    Rinderknecht, H. G.; Rosenberg, M. J.; Zylstra, A. B.; Lahmann, B.; Séguin, F. H.; Frenje, J. A.; Li, C. K.; Gatu Johnson, M.; Petrasso, R. D.; 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.; Bradley, P. A.; Kline, J. L.; Krasheninnikova, N. S.; Kyrala, G. A.; Murphy, T. J.; Schmitt, M. J.; Tregillis, I. L.; Batha, S. H.; Knauer, J. P.; Kilkenny, J. D.

    2015-08-01

    In deuterium-filled inertial confinement fusion implosions, the secondary fusion processes D(3He,p)4He and D(T,n)4He occur, as the primary fusion products 3He and T react in flight with thermal deuterons. In implosions with moderate fuel areal density (˜5-100 mg/cm2), the secondary D-3He 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.

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

    SciTech Connect

    Rinderknecht, H. G. Rosenberg, M. J.; Zylstra, A. B.; Lahmann, B.; Séguin, F. H.; Frenje, J. A.; Li, C. K.; Gatu Johnson, M.; Petrasso, R. D.; 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.; 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.

  6. IMPLOSION OF INDIRECTLY DRIVEN REENTRANT CONE SHELL TARGET

    SciTech Connect

    STEPHENS,RB

    2003-08-01

    OAK-B135 The authors have examined the implosion of an indirectly driven reentrant-cone shell target to clarify the issues attendant on compressing fuel for a fast ignition target. The target design is roughly hydrodynamic equivalent to a NIF cryo-ignition target, but scaled down to be driven by Omega. A sequence of backlit x-radiographs recorded each implosion. The collapse was also modeled with LASNEX, generating simulated radiographs. They compare experimental and simulated diameter, density and symmetry as functions of time near stagnation. The simulations were generally in good agreement with the experiments with respect to the shell, but did not show the opacity due to ablation of gold off the cone; non-thermal gold M-line radiation from the hohlraum wall penetrates the shell and drives this ablation causing some Au to mix into the low density center of the core and into the region between the core and cone. This might be a problem in a cryo-ignition target.

  7. Analysis of NIF experiments with the minimal energy implosion model

    SciTech Connect

    Cheng, B. Kwan, T. J. T.; Wang, Y. M.; Merrill, F. E.; Batha, S. H.; Cerjan, C. J.

    2015-08-15

    We apply a recently developed analytical model of implosion and thermonuclear burn to fusion capsule experiments performed at the National Ignition Facility that used low-foot and high-foot laser pulse formats. Our theoretical predictions are consistent with the experimental data. Our studies, together with neutron image analysis, reveal that the adiabats of the cold fuel in both low-foot and high-foot experiments are similar. That is, the cold deuterium-tritium shells in those experiments are all in a high adiabat state at the time of peak implosion velocity. The major difference between low-foot and high-foot capsule experiments is the growth of the shock-induced instabilities developed at the material interfaces which lead to fuel mixing with ablator material. Furthermore, we have compared the NIF capsules performance with the ignition criteria and analyzed the alpha particle heating in the NIF experiments. Our analysis shows that alpha heating was appreciable only in the high-foot experiments.

  8. Analysis of NIF experiments with the minimal energy implosion model

    NASA Astrophysics Data System (ADS)

    Cheng, B.; Kwan, T. J. T.; Wang, Y. M.; Merrill, F. E.; Cerjan, C. J.; Batha, S. H.

    2015-08-01

    We apply a recently developed analytical model of implosion and thermonuclear burn to fusion capsule experiments performed at the National Ignition Facility that used low-foot and high-foot laser pulse formats. Our theoretical predictions are consistent with the experimental data. Our studies, together with neutron image analysis, reveal that the adiabats of the cold fuel in both low-foot and high-foot experiments are similar. That is, the cold deuterium-tritium shells in those experiments are all in a high adiabat state at the time of peak implosion velocity. The major difference between low-foot and high-foot capsule experiments is the growth of the shock-induced instabilities developed at the material interfaces which lead to fuel mixing with ablator material. Furthermore, we have compared the NIF capsules performance with the ignition criteria and analyzed the alpha particle heating in the NIF experiments. Our analysis shows that alpha heating was appreciable only in the high-foot experiments.

  9. Scaling Laws for Hydrodynamically Equivalent Implosions

    NASA Astrophysics Data System (ADS)

    Murakami, Masakatsu

    2001-10-01

    The EPOC (equivalent physics of confinement) scenario for the proof of principle of high gain inertial confinement fusion is presented, where the key concept "hydrodynamically equivalent implosions" plays a crucial role. Scaling laws on the target and confinement parameters are derived by applying the Lie group analysis to the PDE (partially differential equations) chain of the hydrodynamic system. It turns out that the conventional scaling law based on adiabatic approximation significantly differs from one which takes such energy transport effect as electron heat conduction into account. Confinement plasma parameters of the hot spot such as the central temperature and the areal mass density at peak compression are obtained with a self-similar solution for spherical implosions.

  10. Implosion spectroscopy in Rugby hohlraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Philippe, Franck; Tassin, Veronique; Bitaud, Laurent; Seytor, Patricia; Reverdin, Charles

    2014-10-01

    The rugby hohlraum concept has been validated in previous experiments on the OMEGA laser facility. This new hohlraum type can now be used as a well-characterized experimental platform to study indirect drive implosion, at higher radiation temperatures than would be feasible at this scale with classical cylindrical hohlraums. Recent experiments have focused on the late stages of implosion and hotspot behavior. The capsules included both a thin buried Titanium tracer layer, 0-3 microns from the inner surface, Argon dopant in the deuterium gas fuel and Germanium doped CH shells, providing a variety of spectral signatures of the plasma conditions in different parts of the target. X-ray spectroscopy and imaging were used to study compression, Rayleigh-Taylor instabilities growth at the inner surface and mix between the shell and gas.

  11. Modeling of an Implosion Driven Hypervelocity Launcher

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Higgins, Andrew; Szirti, Daniel; Batchelor, Patrick; Zhang, Fan; Tanguay, Vincent

    2007-06-01

    Modelling work carried out on the implosion driven launcher under concurrent development is presented. The launcher consists of a thin walled metal tube surrounded by explosive which when detonated pinches the tube shut and drives a strong shock into the projectile. The commercial hydrocode LS-DYNA was used to quantitatively and qualitatively evaluate the design parameters of the launcher and their effect on implosion dynamics and performance. These parameters include fill pressure, tube diameter, explosive layer thickness, and explosives tampering. The launcher is primarily modeled using a quasi 2D Arbitrary Langrage Euler formulation. A full 3-D axisymmetric model is also employed. The model is evaluated against experimental data previously collected. Additional developmental work on a second stage launcher taking advantage of a phase velocity between the imploding tube and explosives via the use of angled flyer plates and cones is also carried out.

  12. Prediction of Z-Pinch Implosion Shape from Gas Jet Nozzle Geometry

    NASA Astrophysics Data System (ADS)

    Waisman, E.; Ingermanson, R.; Murphy, H.; Loter, N.; Rix, W.

    1994-03-01

    A technique for predicting the shape of Z-pinch implosions based on gas jet nozzle geometry has been developed and tested against data from argon gas experiments on BLACKJACK 5. The prediction technique involves use of a code which calculates the gas distribution, as a function of nozzle geometry and initial gas input pressure, at the start of the implosion. The calculated gas distribution is then snowplowed to about 0.1 of its initial radius using the measured current waveform. When the snowplow calculation is stopped, the shape of the implosion is compared to experimental data from the associated pinch. The code 2-DRZDELTA calculates the 2-D axisymmetric time dependent solution for the viscous compressible Navier-Stokes equations on a triangular gridded mesh. At the time corresponding to the arrival of pulsed power at the gas jet, the density profile of the expanding argon gas is frozen. This 2-D density profile is then used as the starting point for the 2-D snowplow code which computes the pinch dynamics driven by J x B forces in the snowplow approximation. This technique could be used to predict implosion shapes from nozzle geometry for any driver.

  13. Experimental measurement of Au M-band flux in indirectly-driven double-shell implosions

    SciTech Connect

    Robey, H F; Perry, T S; Park, H S; Amendt, P; Sorce, C M; Compton, S M; Campbell, K M; Knauer, J P

    2004-09-17

    Indirectly-driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility (NIF). In recent double-shell implosions, the inner shell trajectory was shown to exhibit a strong sensitivity to the temporal history of the M-band (2-5 keV) radiation emitted from the Au hohlraum wall. A large time-dependent discrepancy was observed between measurement and simulation of the x-ray flux in this range. In order to better characterize the radiation environment seen in these implosions, an experimental campaign was conducted on the Omega Laser. A number of diagnostics were used to measure both the temporal and spectral nature of the M-band flux. Results were obtained from an absolutely calibrated 12 channel filtered x-ray diode array (Dante) as well as two streaked crystal spectrometers and an absolutely calibrated time-integrated spectrometer (Henway). X-ray backlighting was also used to directly measure the effect of M-band radiation on the trajectory of the inner shell. The data from all diagnostics are shown to be in excellent agreement and provide a consistent picture of the M-band flux. These results are being used to improve the simulation of hohlraum-generated M-band radiation that will be necessary for the design of future double-shell implosions employing higher Z inner shells.

  14. Spherical ion kinetic simulations of DT implosions

    SciTech Connect

    Vidal, F.; Matte, J.P.; Casanova, M.; Larroche, O.

    1995-10-01

    The implosion of the DT plasma in an ablatively driven glass microballoon was simulated with a spherical ion kinetic code. The ion velocity distribution functions were strongly non-Maxwellian, and mostly depleted of fast ions. A high viscosity contributed to fuel heating, while large ion heat fluxes towards the pusher strongly cooled the fuel. This latter kinetic effect may explain in part why hydrodynamic simulations usually predict higher neutron yields than are measured.

  15. Mosquito densonucleosis virus non-structural protein NS2 is necessary for a productive infection

    SciTech Connect

    Azarkh, Eugene; Robinson, Erin; Hirunkanokpun, Supanee; Afanasiev, Boris; Kittayapong, Pattamaporn; Carlson, Jonathan Corsini, Joe

    2008-04-25

    Mosquito densonucleosis viruses synthesize two non-structural proteins, NS1 and NS2. While NS1 has been studied relatively well, little is known about NS2. Antiserum was raised against a peptide near the N-terminus of NS2, and used to conduct Western blot analysis and immuno-fluorescence assays. Western blots revealed a prominent band near the expected size (41 kDa). Immuno-fluorescence studies of mosquito cells transfected with AeDNV indicate that NS2 has a wider distribution pattern than does NS1, and the distribution pattern appears to be a function of time post-infection. Nuclear localization of NS2 requires intact C-terminus but does not require additional viral proteins. Mutations ranging from complete NS2 knock-out to a single missense amino acid substitution in NS2 can significantly reduce viral replication and production of viable progeny.

  16. Demonstration of implosion symmetry in NIF scale 0.7 Hohlraums

    SciTech Connect

    Seifter, Achim; Kyrala, George A; Goldman, S Robert; Hoffman, Nelson M

    2008-01-01

    Implosions using inertial confinement fusion must be highly symmetric to achieve ignition on the National Ignition Facility. This requires precise control of the drive symmetry from the radiation incident on the ignition capsule. For indirect drive implosions, low mode residual perturbations in the drive are generated by the laser-heated hohlraurn geometry. To diagnose the drive symmetry, previous experiments used simulated capsules by which the selfemission x-rays from gas in the center of capsule during the implosion are used to infer the shape of the drive. However, those experiments used hohlraurn radiation temperatures higher than 200 eV (Hauer et al., 2007, Murphy et aI., 1998a, Murphy et al., 1998b) with small NOVA scale hohlraurns under which conditions the symcaps produced large x-ray signals. During the foot of the NIF ignition pulse where controlling the symmetry has been shown to be crucial for obtaining a symmetric implosion (Clark et aI., 2008), the radiation drive is much smaller, reducing the x-ray emission from the imploded capsule. For the first time, the feasibility of using symcaps to diagnose the radiation drive for low radiation temperatures, < 120 eV and large 0.7 linear scale NIF Rev3.1 (Haan et al., 2008) vacuum hohlraurns is demonstrated. Here we used experiments at the Omega laser facility to demonstrate and develop the symcap technique for tuning the symmetry of the NIF ignition capsule in the foot of the drive pulse.

  17. Using high-intensity laser-generated energetic protons to radiograph directly driven implosions.

    PubMed

    Zylstra, A B; Li, C K; Rinderknecht, H G; Séguin, F H; Petrasso, R D; Stoeckl, C; Meyerhofer, D D; Nilson, P; Sangster, T C; Le Pape, S; Mackinnon, A; Patel, P

    2012-01-01

    The recent development of petawatt-class lasers with kilojoule-picosecond pulses, such as OMEGA EP [L. Waxer et al., Opt. Photonics News 16, 30 (2005)], provides a new diagnostic capability to study inertial-confinement-fusion (ICF) and high-energy-density (HED) plasmas. Specifically, petawatt OMEGA EP pulses have been used to backlight OMEGA implosions with energetic proton beams generated through the target normal sheath acceleration (TNSA) mechanism. This allows time-resolved studies of the mass distribution and electromagnetic field structures in ICF and HED plasmas. This principle has been previously demonstrated using Vulcan to backlight six-beam implosions [A. J. Mackinnon et al., Phys. Rev. Lett. 97, 045001 (2006)]. The TNSA proton backlighter offers better spatial and temporal resolution but poorer spatial uniformity and energy resolution than previous D(3)He fusion-based techniques [C. Li et al., Rev. Sci. Instrum. 77, 10E725 (2006)]. A target and the experimental design technique to mitigate potential problems in using TNSA backlighting to study full-energy implosions is discussed. The first proton radiographs of 60-beam spherical OMEGA implosions using the techniques discussed in this paper are presented. Sample radiographs and suggestions for troubleshooting failed radiography shots using TNSA backlighting are given, and future applications of this technique at OMEGA and the NIF are discussed. PMID:22299955

  18. Time-resolved spatial distribution of plasma in the ablation of a Ba₀.₆Sr₀.₄TiO₃ target by 25 ns KrF ultraviolet laser

    SciTech Connect

    Lagrange, J. F.; Wolfman, J.; Motret, O.; Hermann, J.

    2014-10-07

    We performed radially and longitudinally time-resolved plasma analysis during pulsed laser deposition of Ba₀.₆Sr₀.₄TiO₃ thin films. The plasma is shown to be optically thick and strongly non-uniform during the early expansion phase and the resonance line Ba II (455.4 nm) is strongly self-reversed during this time. Plasma temperature and electron density were obtained by comparing experimental emission spectra with the spectral radiance computed for a non-uniform plasma in local thermal equilibrium.

  19. X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores

    SciTech Connect

    Epstein, R.; Goncharov, V. N.; Marshall, F. J.; Betti, R.; Nora, R.; Christopherson, A. R.; Golovkin, I. E.; MacFarlane, J. J.

    2015-02-15

    Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus'kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion's central hot spot, the hot-spot “fuel–shell” mix mass can be inferred.

  20. Diagnosing implosion performance at the National Ignition Facility (NIF) by means of neutron spectrometry

    NASA Astrophysics Data System (ADS)

    Frenje, J. A.; Bionta, R.; Bond, E. J.; Caggiano, J. A.; Casey, D. T.; Cerjan, C.; Edwards, J.; Eckart, M.; Fittinghoff, D. N.; Friedrich, S.; Glebov, V. Yu.; Glenzer, S.; Grim, G.; Haan, S.; Hatarik, R.; Hatchett, S.; Gatu Johnson, M.; Jones, O. S.; Kilkenny, J. D.; Knauer, J. P.; Landen, O.; Leeper, R.; Le Pape, S.; Lerche, R.; Li, C. K.; Mackinnon, A.; McNaney, J.; Merrill, F. E.; Moran, M.; Munro, D. H.; Murphy, T. J.; Petrasso, R. D.; Rygg, R.; Sangster, T. C.; Séguin, F. H.; Sepke, S.; Spears, B.; Springer, P.; Stoeckl, C.; Wilson, D. C.

    2013-04-01

    The neutron spectrum from a cryogenically layered deuterium-tritium (dt) implosion at the National Ignition Facility (NIF) provides essential information about the implosion performance. From the measured primary-neutron spectrum (13-15 MeV), yield (Yn) and hot-spot ion temperature (Ti) are determined. From the scattered neutron yield (10-12 MeV) relative to Yn, the down-scatter ratio, and the fuel areal density (ρR) are determined. These implosion parameters have been diagnosed to an unprecedented accuracy with a suite of neutron-time-of-flight spectrometers and a magnetic recoil spectrometer implemented in various locations around the NIF target chamber. This provides good implosion coverage and excellent measurement complementarity required for reliable measurements of Yn, Ti and ρR, in addition to ρR asymmetries. The data indicate that the implosion performance, characterized by the experimental ignition threshold factor, has improved almost two orders of magnitude since the first shot taken in September 2010. ρR values greater than 1 g cm-2 are readily achieved. Three-dimensional semi-analytical modelling and numerical simulations of the neutron-spectrometry data, as well as other data for the hot spot and main fuel, indicate that a maximum hot-spot pressure of ˜150 Gbar has been obtained, which is almost a factor of two from the conditions required for ignition according to simulations. Observed Yn are also 3-10 times lower than predicted. The conjecture is that the observed pressure and Yn deficits are partly explained by substantial low-mode ρR asymmetries, which may cause inefficient conversion of shell kinetic energy to hot-spot thermal energy at stagnation.

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

    PubMed Central

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

    2013-01-01

    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, Pc, 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/D0, 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 Pc and the time scale (where Ri 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/D0, 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, PcV , 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 , but that the shape and amplitudes of the pressure records are strongly affected by the mode number. PMID:24353473

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

    PubMed

    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

  3. Deletion of the C-terminal region of dengue virus nonstructural protein 1 (NS1) abolishes anti-NS1-mediated platelet dysfunction and bleeding tendency.

    PubMed

    Chen, Mei-Chun; Lin, Chiou-Feng; Lei, Huan-Yao; Lin, Shih-Chao; Liu, Hsiao-Sheng; Yeh, Trai-Ming; Anderson, Robert; Lin, Yee-Shin

    2009-08-01

    The mechanisms underlying dengue hemorrhagic disease are incompletely understood. We previously showed that anti-dengue virus (DV) nonstructural protein 1 (NS1) Abs cross-react with human platelets and inhibit platelet aggregation. Based on sequence homology alignment, the cross-reactive epitopes reside in the C-terminal region of DV NS1. In this study, we compared the effects of Abs against full-length DV NS1 and NS1 lacking the C-terminal aa 271 to 352 (designated DeltaC NS1). Anti-DeltaC NS1 Abs exhibited lower platelet binding activity than that of anti-full-length NS1. Anti-full-length NS1 but not anti-DeltaC NS1 Abs inhibited platelet aggregation, which was shown to involve integrin alpha(IIb)beta(3) inactivation. We found that the bleeding time in full-length NS1-hyperimmunized mice was longer than that in the normal control mice. By contrast, DeltaC NS1-hyperimmunized mice showed a bleeding time similar to that of normal control mice. Passively administered anti-DV NS1, but not anti-DeltaC NS1, Ab level decreased markedly in serum and this decrease was correlated with Ab binding to platelets. A transient platelet loss in the circulation was observed after anti-DV NS1, but not anti-DeltaC NS1, Ab administration. In summary, platelet dysfunction and bleeding tendency are induced by anti-full-length DV NS1 but not by anti-DeltaC NS1 Abs. These findings may be important not only for understanding dengue hemorrhagic disease pathogenesis but also for dengue vaccine development. PMID:19592650

  4. Towards an Integrated Model of the NIC Layered Implosions

    SciTech Connect

    Jones, O S; Callahan, D A; Cerjan, C J; Clark, D S; Edwards, M J; Glenzer, S H; Marinak, M M; Meezan, N B; Milovich, J L; Olson, R E; Patel, M V; Robey, H F; Sepke, S M; Spears, B K; Springer, P T; Weber, S V; Wilson, D C

    2011-10-31

    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 15-45% of the calculated yields.

  5. Magnetic Rayleigh-Taylor instability mitigation and efficient radiation production in gas puff Z-pinch implosions

    SciTech Connect

    Sze, H.; Levine, J. S.; Banister, J.; Failor, B. H.; Qi, N.; Steen, P.; Velikovich, A. L.; Davis, J.; Wilson, A.

    2007-05-15

    Large radius Z-pinches are inherently susceptible to the magnetic Rayleigh-Taylor (RT) instability because of their relatively long acceleration path. This has been reflected in a significant reduction of the argon K-shell yield as was observed when the diameter of the load was increased from 2.5 to >4 cm. Recently, an approach was demonstrated to overcome the challenge with a structured gas puff load that mitigates the RT instability, enhances the energy coupling, and leads to a high compression, high yield Z-pinch. The novel load consists of a 'pusher', outer region plasma that carries the current and couples energy from the driver, a 'stabilizer', inner region plasma that mitigates the RT growth, and a ''radiator,'' high-density center jet plasma that is heated and compressed to radiate. In 3.5-MA, 200-ns, 12-cm initial diameter implosions, the Ar K-shell yield has increased by a factor of 2, to 21 kJ, matching the yields obtained on the same accelerator with 100-ns, 2.5-cm-diam implosions. Further tests of such structured Ar gas load on {approx}6 MA, 200-ns accelerators have achieved >80 kJ. From laser diagnostics and measurements of the K-shell and extreme ultraviolet emission, initial gas distribution and implosion trajectories were obtained, illustrating the RT suppression and stabilization of the imploding plasma, and identifying the radiation source region in a structured gas puff load. Magnetohydrodynamic simulations, started from actual initial density profiles, reproduce many features of the measurements both qualitatively and quantitatively.

  6. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions. PMID:25607820

  7. The charge pump PLL clock generator designed for the 1.56 ns bin size time-to-digital converter pixel array of the Timepix3 readout ASIC

    NASA Astrophysics Data System (ADS)

    Fu, Y.; Brezina, C.; Desch, K.; Poikela, T.; Llopart, X.; Campbell, M.; Massimiliano, D.; Gromov, V.; Kluit, R.; van Beauzekom, M.; Zappon, F.; Zivkovic, V.

    2014-01-01

    Timepix3 is a newly developed pixel readout chip which is expected to be operated in a wide range of gaseous and silicon detectors. It is made of 256 × 256 pixels organized in a square pixel-array with 55 μm pitch. Oscillators running at 640 MHz are distributed across the pixel-array and allow for a highly accurate measurement of the arrival time of a hit. This paper concentrates on a low-jitter phase locked loop (PLL) that is located in the chip periphery. This PLL provides a control voltage which regulates the actual frequency of the individual oscillators, allowing for compensation of process, voltage, and temperature variations.

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

    DOE PAGESBeta

    Igumenshchev, Igor 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.; et al

    2016-05-04

    In this study, 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 to 20 μm); and imperfect pointing, power balance, and timing of the beams (with typical σrms ~10 microns, 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,more » 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 σrms are reduced to less than 5 μm and 5%, respectively.« less

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    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.

    2009-05-15

    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 et al., 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.

  11. Radiography of magnetically-driven implosions of initially solid beryllium cylindrical shells for equation-of-state studies at the Z pulsed-power facility

    NASA Astrophysics Data System (ADS)

    McBride, Ryan

    2011-06-01

    The Z accelerator delivers approximately 4-MV, 26-MA electrical pulses with adjustable current rise times of 100--600 ns, as well as adjustable pulse waveforms. The magnetic pressure produced is used for various applications, including magnetically-driven implosions. The Z-Beamlet Laser (ZBL) is a pulsed (0.3-1.5 ns), multi-kJ, TW-class Nd:glass laser system that provides x-ray radiography capabilities for Z experiments. This talk focuses primarily on the radiography diagnostic used to study the magnetically-driven implosions of initially solid cylindrical shells (also referred to as ``liners''). Specifically, we discuss the 6.151-keV monochromatic backlighting system and its use in obtaining radiographs of imploding beryllium (Be) liners. The high transmission efficiency of 6.151-keV photons in Be allowed us to obtain radiographs with finite transmission throughout the radial extent of the imploding liners. Abel inverting these data, we have obtained time-resolved measurements of the imploding liner's density as a function of both axial and radial location throughout the field of view. These data are allowing us to study magneto-Rayleigh-Taylor (MRT) growth for inertial-confinement-fusion applications, as well as compression-wave propagation for equation-of-state studies (see talks by R.L. Lemke and M.R. Martin). Additionally, Z's pulse-shaping capabilities have enabled us to obtain data for both shock- and quasi-isentropically-compressed Be. Example data from MRT, shock-compression, and quasi-isentropic-compression experiments will be shown. We will also discuss planned upgrades to 25-keV radiography that will allow us to study materials with opacities beyond that of beryllium. This work was done in collaboration with R.W. Lemke, M.R. Martin, J.-P. Davis, M.D. Knudson, D.B. Sinars, S.A. Slutz, C.A. Jennings, M.E. Cuneo, D.G. Flicker, and M.C. Herrmann. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin company, for the US

  12. Odyssey/NS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These two views of Mars were made with data taken by the neutron spectrometer component of NASA's Mars Odyssey gamma ray spectrometer suite. These maps show epithermal neutron flux, which is sensitive to the amount of hydrogen present.

    The first view was made shortly after the Mars Odyssey science mission began in Feb. 2002, during late summer in the south. The magenta region in the south is due to large amounts of water ice buried a fraction of a meter beneath the surface. The amount of ice is approximately 60 percent by volume. At that time the buried ice in the north was not visible because it was covered with a thick cap of carbon dioxide (dry-ice) frost.

    The second view was made in November 2002 as Mars enters summer in the north. In this view the ice-rich regions in the north are now visible because the thick carbon dioxide frost has evaporated, and the ice-rich regions in the south are beginning to be obscured by the formation of wintertime seasonal frost. The ice content in the north is even greater than it is in the south, though it is not yet known by how much.

    JPL, a division of the California Institute of Technology in Pasadena, manages the 2001 Mars Odyssey mission for NASA's Office of Space Science in Washington, D.C. Investigators at Arizona State University in Tempe, the University of Arizona in Tucson and NASA's Johnson Space Center,Houston, operate the science instruments. The gamma-ray spectrometer was provided by the University of Arizona in collaboration with the Russian Aviation and Space Agency, which provided the high-energy neutron detector, and the Los Alamos National Laboratories, New Mexico, which provided the neutron spectrometer. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL.

  13. Characterization of Dengue Virus NS4A and NS4B Protein Interaction

    PubMed Central

    Zou, Jing; Xie, Xuping; Wang, Qing-Yin; Dong, Hongping; Lee, Michelle Yueqi; Kang, Congbao

    2015-01-01

    ABSTRACT Flavivirus replication is mediated by a membrane-associated replication complex where viral membrane proteins NS2A, NS2B, NS4A, and NS4B serve as the scaffold for the replication complex formation. Here, we used dengue virus serotype 2 (DENV-2) as a model to characterize viral NS4A-NS4B interaction. NS4A interacts with NS4B in virus-infected cells and in cells transiently expressing NS4A and NS4B in the absence of other viral proteins. Recombinant NS4A and NS4B proteins directly bind to each other with an estimated Kd (dissociation constant) of 50 nM. Amino acids 40 to 76 (spanning the first transmembrane domain, consisting of amino acids 50 to 73) of NS4A and amino acids 84 to 146 (also spanning the first transmembrane domain, consisting of amino acids 101 to 129) of NS4B are the determinants for NS4A-NS4B interaction. Nuclear magnetic resonance (NMR) analysis suggests that NS4A residues 17 to 80 form two amphipathic helices (helix α1, comprised of residues 17 to 32, and helix α2, comprised of residues 40 to 47) that associate with the cytosolic side of endoplasmic reticulum (ER) membrane and helix α3 (residues 52 to 75) that transverses the ER membrane. In addition, NMR analysis identified NS4A residues that may participate in the NS4A-NS4B interaction. Amino acid substitution of these NS4A residues exhibited distinct effects on viral replication. Three of the four NS4A mutations (L48A, T54A, and L60A) that affected the NS4A-NS4B interaction abolished or severely reduced viral replication; in contrast, two NS4A mutations (F71A and G75A) that did not affect NS4A-NS4B interaction had marginal effects on viral replication, demonstrating the biological relevance of the NS4A-NS4B interaction to DENV-2 replication. Taken together, the study has provided experimental evidence to argue that blocking the NS4A-NS4B interaction could be a potential antiviral approach. IMPORTANCE Flavivirus NS4A and NS4B proteins are essential components of the ER membrane

  14. Modeling, measuring, and mitigating instability growth in liner implosions on Z

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle

    2015-11-01

    Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. In this talk, we will discuss the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. We present simulations that show electro-thermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent magneto-Rayleigh-Taylor (MRT) instability growth. We discuss measurement results from experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electro-thermal instability growth on well-characterized initially solid aluminum or beryllium rods driven with a 20 MA, 100 ns risetime current pulse. These measurements show good agreement with electro-thermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone. Recent experiments have confirmed simulation predictions of dramatically reduced instability growth in solid metallic rods when thick dielectric coatings are used to mitigate density perturbations arising from the electro-thermal instability. These results provide further evidence that the inherent surface roughness of the target is not the dominant seed for the MRT instability, in contrast with most inertial confinement fusion approaches. These results suggest a new technique for substantially reducing the integral MRT growth in magnetically driven implosions. Indeed, recent results on the Z facility with 100 km/s Al and Be liner implosions show substantially reduced growth. These new results include axially magnetized, CH-coated beryllium liner radiographs in which the inner liner surface is observed to be remarkably straight and uniform at a radius of about 120 microns (convergence ratio ~20). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Resistance Analyses of HCV NS3/4A Protease and NS5B Polymerase from Clinical Studies of Deleobuvir and Faldaprevir

    PubMed Central

    Berger, Kristi L.; Sarrazin, Christoph; Nelson, David R.; Scherer, Joseph; Sha, Nanshi; Marquis, Martin; Côté-Martin, Alexandra; Vinisko, Richard; Stern, Jerry O.; Mensa, Federico J.; Kukolj, George

    2016-01-01

    Background & Aim The resistance profile of anti-hepatitis C virus (HCV) agents used in combination is important to guide optimal treatment regimens. We evaluated baseline and treatment-emergent NS3/4A and NS5B amino-acid variants among HCV genotype (GT)-1a and -1b-infected patients treated with faldaprevir (HCV protease inhibitor), deleobuvir (HCV polymerase non-nucleoside inhibitor), and ribavirin in multiple clinical studies. Methods HCV NS3/4A and NS5B population sequencing (Sanger method) was performed on all baseline plasma samples (n = 1425 NS3; n = 1556 NS5B) and on post-baseline plasma samples from patients with virologic failure (n = 113 GT-1a; n = 221 GT-1b). Persistence and time to loss of resistance-associated variants (RAVs) was estimated using Kaplan–Meier analysis. Results Faldaprevir RAVs (NS3 R155 and D168) and deleobuvir RAVs (NS5B 495 and 496) were rare (<1%) at baseline. Virologic response to faldaprevir/deleobuvir/ribavirin was not compromised by common baseline NS3 polymorphisms (e.g. Q80K in 17.5% of GT-1a) or by NS5B A421V, present in 20% of GT-1a. In GT-1b, alanine at NS5B codon 499 (present in 15% of baseline sequences) was associated with reduced response. Treatment-emergent RAVs consolidated previous findings: NS3 R155 and D168 were key faldaprevir RAVs; NS5B A421 and P495 were key deleobuvir RAVs. Among on-treatment virologic breakthroughs, RAVs emerged in both NS3 and NS5B (>90%). Virologic relapse was associated with RAVs in both NS3 and NS5B (53% GT-1b; 52% GT-1b); some virologic relapses had NS3 RAVs only (47% GT-1a; 17% GT-1b). Median time to loss of GT-1b NS5B P495 RAVs post-treatment (5 months) was less than that of GT-1b NS3 D168 (8.5 months) and GT-1a R155 RAVs (11.5 months). Conclusion Faldaprevir and deleobuvir RAVs are more prevalent among virologic failures than at baseline. Treatment response was not compromised by common NS3 polymorphisms; however, alanine at NS5B amino acid 499 at baseline (wild-type in GT-1a

  17. Implosion dynamics measurements at the National Ignition Facility

    SciTech Connect

    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.; 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

  18. Implosion dynamics measurements at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    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

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

    SciTech Connect

    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.; 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.

  20. Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion

    NASA Astrophysics Data System (ADS)

    Calamy, H.; Lassalle, F.; Loyen, A.; Zucchini, F.; Chittenden, J. P.; Hamann, F.; Maury, P.; Georges, A.; Bedoch, J. P.; Morell, A.

    2008-01-01

    The Sphinx machine [F. Lassalle et al., "Status on the SPHINX machine based on the 1microsecond LTD technology"] based on microsecond linear transformer driver (LTD) technology is used to implode an aluminium wire array with an outer diameter up to 140mm and maximum current from 3.5to5MA. 700to800ns implosion Z-pinch experiments are performed on this driver essentially with aluminium. Best results obtained before the improvement described in this paper were 1-3TW radial total power, 100-300kJ total yield, and 20-30kJ energy above 1keV. An auxiliary generator was added to the Sphinx machine in order to allow a multi microsecond current to be injected through the wire array load before the start of the main current. Amplitude and duration of this current prepulse are adjustable, with maxima ˜10kA and 50μs. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. Total power was multiplied by a factor of 6, total yield by a factor of 2.5 with a reproducible behavior. This paper presents experimental results, magnetohydrodynamic simulations, and analysis of the effect of such a long current prepulse.

  1. Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion

    SciTech Connect

    Calamy, H.; Lassalle, F.; Loyen, A.; Zucchini, F.; Chittenden, J. P.; Hamann, F.; Maury, P.; Georges, A.; Bedoch, J. P.; Morell, A.

    2008-01-15

    The Sphinx machine [F. Lassalle et al., 'Status on the SPHINX machine based on the 1microsecond LTD technology'] based on microsecond linear transformer driver (LTD) technology is used to implode an aluminium wire array with an outer diameter up to 140 mm and maximum current from 3.5 to 5 MA. 700 to 800 ns implosion Z-pinch experiments are performed on this driver essentially with aluminium. Best results obtained before the improvement described in this paper were 1-3 TW radial total power, 100-300 kJ total yield, and 20-30 kJ energy above 1 keV. An auxiliary generator was added to the Sphinx machine in order to allow a multi microsecond current to be injected through the wire array load before the start of the main current. Amplitude and duration of this current prepulse are adjustable, with maxima {approx}10 kA and 50 {mu}s. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. Total power was multiplied by a factor of 6, total yield by a factor of 2.5 with a reproducible behavior. This paper presents experimental results, magnetohydrodynamic simulations, and analysis of the effect of such a long current prepulse.

  2. Cryogenic thermonuclear fuel implosions on the National Ignition Facility

    SciTech Connect

    Glenzer, S. H.; Callahan, D. A.; MacKinnon, A. J.; Alger, E. T.; Berger, R. L.; Bernstein, L. A.; Bleuel, D. L.; Bradley, D. K.; Burkhart, S. C.; Burr, R.; Caggiano, J. A.; Castro, C.; Choate, C.; Clark, D. S.; Celliers, P.; Cerjan, C. J.; Collins, G. W.; Dewald, E. L.; DiNicola, P.; DiNicola, J. M.; and others

    2012-05-15

    The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 MJ produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 {mu}m diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 {+-} 3) {mu}m, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 {+-} 0.09) g cm{sup -2} result in fuel densities approaching 600 g cm{sup -3}. The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 {+-} 0.1) keV that is measured with neutron time of flight spectra. The hot-spot plasma produces a total fusion neutron yield of 10{sup 15} that is measured with the magnetic recoil spectrometer and nuclear activation diagnostics that indicate a 14.1 MeV yield of (7.5{+-}0.1) Multiplication-Sign 10{sup 14} which is 70% to 75% of the total fusion yield due to the high areal density. Gamma ray measurements provide the duration of nuclear activity of (170 {+-} 30) ps. These indirect-drive implosions result in the highest areal densities

  3. Cryogenic thermonuclear fuel implosions on the National Ignition Facilitya)

    NASA Astrophysics Data System (ADS)

    Glenzer, S. H.; Callahan, D. A.; MacKinnon, A. J.; Kline, J. L.; Grim, G.; Alger, E. T.; Berger, R. L.; Bernstein, L. A.; Betti, R.; Bleuel, D. L.; Boehly, T. R.; Bradley, D. K.; Burkhart, S. C.; Burr, R.; Caggiano, J. A.; Castro, C.; Casey, D. T.; Choate, C.; Clark, D. S.; Celliers, P.; Cerjan, C. J.; Collins, G. W.; Dewald, E. L.; DiNicola, P.; DiNicola, J. M.; Divol, L.; Dixit, S.; Döppner, T.; Dylla-Spears, R.; Dzenitis, E.; Eckart, M.; Erbert, G.; Farley, D.; Fair, J.; Fittinghoff, D.; Frank, M.; Frenje, L. J. A.; Friedrich, S.; Casey, D. T.; Gatu Johnson, M.; Gibson, C.; Giraldez, E.; Glebov, V.; Glenn, S.; Guler, N.; Haan, S. W.; Haid, B. J.; Hammel, B. A.; Hamza, A. V.; Haynam, C. A.; Heestand, G. M.; Hermann, M.; Hermann, H. W.; Hicks, D. G.; Hinkel, D. E.; Holder, J. P.; Holunda, D. M.; Horner, J. B.; Hsing, W. W.; Huang, H.; Izumi, N.; Jackson, M.; Jones, O. S.; Kalantar, D. H.; Kauffman, R.; Kilkenny, J. D.; Kirkwood, R. K.; Klingmann, J.; Kohut, T.; Knauer, J. P.; Koch, J. A.; Kozioziemki, B.; Kyrala, G. A.; Kritcher, A. L.; Kroll, J.; La Fortune, K.; Lagin, L.; Landen, O. L.; Larson, D. W.; LaTray, D.; Leeper, R. J.; Le Pape, S.; Lindl, J. D.; Lowe-Webb, R.; Ma, T.; McNaney, J.; MacPhee, A. G.; Malsbury, T. N.; Mapoles, E.; Marshall, C. D.; Meezan, N. B.; Merrill, F.; Michel, P.; Moody, J. D.; Moore, A. S.; Moran, M.; Moreno, K. A.; Munro, D. H.; Nathan, B. R.; Nikroo, A.; Olson, R. E.; Orth, C. D.; Pak, A. E.; Patel, P. K.; Parham, T.; Petrasso, R.; Ralph, J. E.; Rinderknecht, H.; Regan, S. P.; Robey, H. F.; Ross, J. S.; Rosen, M. D.; Sacks, R.; Salmonson, J. D.; Saunders, R.; Sater, J.; Sangster, C.; Schneider, M. B.; Séguin, F. H.; Shaw, M. J.; Spears, B. K.; Springer, P. T.; Stoeffl, W.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Town, R. P. J.; Walters, C.; Weaver, S.; Weber, S. V.; Wegner, P. J.; Whitman, P. K.; Widmann, K.; Widmayer, C. C.; Wilde, C. H.; Wilson, D. C.; Van Wonterghem, B.; MacGowan, B. J.; Atherton, L. J.; Edwards, M. J.; Moses, E. I.

    2012-05-01

    The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 MJ produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 μm diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 ± 3) μm, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 ± 0.09) g cm-2 result in fuel densities approaching 600 g cm-3. The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 ± 0.1) keV that is measured with neutron time of flight spectra. The hot-spot plasma produces a total fusion neutron yield of 1015 that is measured with the magnetic recoil spectrometer and nuclear activation diagnostics that indicate a 14.1 MeV yield of (7.5±0.1)×1014 which is 70% to 75% of the total fusion yield due to the high areal density. Gamma ray measurements provide the duration of nuclear activity of (170 ± 30) ps. These indirect-drive implosions result in the highest areal densities and neutron yields achieved on laser facilities to date

  4. NS&T Management Observations

    SciTech Connect

    Gianotto, David

    2014-09-01

    The INL Management Observation Program (MOP) is designed to improve managers and supervisors understanding of work being performed by employees and the barriers impacting their success. The MOP also increases workers understanding of managements’ expectations as they relate to safety, security, quality, and work performance. Management observations (observations) are designed to improve the relationship and trust between employees and managers through increased engagement and interactions between managers and researchers in the field. As part of continuous improvement, NS&T management took initiative to focus on the participation and quality of observations in FY 14. This quarterly report is intended to (a) summarize the participation and quality of management’s observations, (b) assess observations for commonalities or trends related to facility or process barriers impacting research, and (c) provide feedback and make recommendations for improvements NS&T’s MOP.

  5. NS&T MANAGEMENT OBSERVATIONS

    SciTech Connect

    Gianotto, David

    2014-06-01

    The INL Management Observation Program (MOP) is designed to improve managers and supervisors understanding of work being performed by employees and the barriers impacting their success. The MOP also increases workers understanding of managements’ expectations as they relate to safety, security, quality, and work performance. Management observations (observations) are designed to improve the relationship and trust between employees and managers through increased engagement and interactions between managers and researchers in the field. As part of continuous improvement, NS&T management took initiative to focus on the participation and quality of observations in FY 14. This quarterly report is intended to (a) summarize the participation and quality of management’s observations, (b) assess observations for commonalities or trends related to facility or process barriers impacting research, and (c) provide feedback and make recommendations for improvements NS&T’s MOP.

  6. PS II model-based simulations of single turnover flash-induced transients of fluorescence yield monitored within the time domain of 100 ns-10 s on dark-adapted Chlorella pyrenoidosa cells.

    PubMed

    Belyaeva, N E; Schmitt, F-J; Steffen, R; Paschenko, V Z; Riznichenko, G Yu; Chemeris, Yu K; Renger, G; Rubin, A B

    2008-01-01

    The set up described in Steffen et al. (Biochemistry 40:173-180, 2001) was used to monitor in the time domain from 100 ns to 10 s single turnover flash-induced transients of the normalized fluorescence yield (SFITFY) on dark-adapted cells of the thermophilic algae Chlorella pyrenoidosa Chick. Perfect data fit was achieved within the framework of a previously proposed model for the PS II reaction pattern (Lebedeva et al., Biophysics 47:968-980, 2002; Belyaeva et al., Biophysics 51:860-872, 2006) after its modification by taking into account nonradiative decay processes including nonphotochemical quenching due to time-dependent populations of P680(+*) and (3)Car. On the basis of data reported in the literature, a consistent set of rate constants was obtained for electron transfer at the donor and acceptor sides of PS II, pH in lumen and stroma, the initial redox state of plastoquinone pool and the rate of plastoquinone oxidation. The evaluation of the rate constant values of dissipative processes due to quenching by carotenoid triplets in antennae and P680(+*)Q(A)(-*) recombination as well as the initial state populations after excitation with a single laser flash are close to that outlined in (Steffen et al., Biochemistry 44:3123-3133, 2005a). The simulations based on the model of the PS II reaction pattern provide information on the time courses of population probabilities of different PS II states. We analyzed the maximum (F(m)(STF)) and minimum (F(0)) of the normalized FL yield dependence on the rate of the recombination processes (radiative and dissipative nonradiative) and of P680(+*) reduction. The developed PS II model provides a basis for theoretical comparative analyses of time-dependent fluorescence signals, observed at different photosynthetic samples under various conditions (e.g. presence of herbicides, other stress conditions, excitation with actinic pulses of different intensity, and duration). PMID:18937044

  7. X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores

    SciTech Connect

    Epstein, R.; Goncharov, V. N.; Marshall, F. J.; Betti, R.; Nora, R.; Christopherson, A. R.; Golovkin, I. E.; MacFarlane, J. J.

    2015-02-01

    Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus’kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion’s central hot spot, the hot-spot “fuel–shell” mix mass can be inferred.

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

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; 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.; Izumi, N.; Kyrala, G. A.; Moody, J. D.; Patel, P. K.; Ralph, J. E.; Rygg, J. R.; Sepke, S. M.; Spears, B. K.; Tommasini, R.; Town, R. P. J.; Biener, J.; Bionta, R. M.; Bond, E. J.; Caggiano, J. A.; Eckart, M. J.; Gatu Johnson, M.; Grim, G. P.; Hamza, A. V.; Hartouni, E. P.; Hatarik, R.; Hoover, D. E.; Kilkenny, J. D.; Kozioziemski, B. J.; Kroll, J. J.; McNaney, J. M.; Nikroo, A.; Sayre, D. B.; Stadermann, M.; Wild, C.; Yoxall, B. E.; Landen, O. L.; Hsing, W. W.; Edwards, M. J.

    2015-06-01

    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 × 1015 neutrons, 40% of the 1D simulated yield.

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

    SciTech Connect

    Meezan, N. B. 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.; 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.

  10. Studying shock dynamics and in-flight ρR asymmetries in NIF implosions using proton spectroscopy

    NASA Astrophysics Data System (ADS)

    Zylstra, Alex

    2014-10-01

    Ignition-scale, indirect-drive implosions of CH capsules filled with D3He gas have been studied with proton spectroscopy at the NIF. Spectral measurements of D3He protons produced at the shock-bang time provide information about the shock dynamics and in-flight characteristics of these implosions. The observed energy downshift of the D3He-proton spectra are interpreted with a self-consistent 1-D model to infer ρR, shell Rcm, and yield at this time. 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 generate lower ρR at shock-bang time. This is most likely due to a larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast implosions (~400 ps). These differences are determined from the D3He proton spectra and in-flight x-ray radiography data, and it is found to contradict radiation-hydrodynamic simulations, which predict a 700-800 ps temporal difference independent of coasting time. A large variation in the shock proton yield is also observed in the dataset, which is interpreted with a Guderley shock model and found to correspond to ~2× variation in incipient hot-spot adiabat caused by shock heating. This variation may affect the compressibility of NIF implosions. Finally, data from multiple proton spectrometers placed at the pole and equator reveal large ρR asymmetries, which are interpreted as mode-2 polar or azimuthal asymmetries. At the shock-bang time (CR ~ 3-5), asymmetry amplitudes >=10% are routinely observed. Compared to compression-bang time x-ray self-emission symmetry, no apparent asymmetry-amplitude growth is observed, which is in contradiction to several growth models. This is attributed to a lack of correspondence between shell and hot-spot symmetry at peak compression, as discussed in recent computational studies. This work was

  11. Deuterium gas-puff Z-pinch implosions on the Z accelerator

    SciTech Connect

    Coverdale, C. A.; Deeney, C.; Ruiz, C. L.; Velikovich, A. L.; Davis, J.; Clark, R. W.; Chong, Y. K.; Apruzese, J. P.; Chittenden, J.; Chantrenne, S.; Franklin, J.; LePell, P. D.; Cooper, G. W.; Nelson, A. J.; Levine, J.; Banister, J.

    2007-05-15

    Experiments on the Z accelerator with deuterium gas-puff implosions have produced up to 3.7x10{sup 13} ({+-}20%) neutrons at 2.34 MeV ({+-}0.10 MeV). Although the mechanism for generating these neutrons was not definitively identified, this neutron output is 100 times more than previously observed from neutron-producing experiments at Z. Dopant gases in the deuterium (argon and chlorine) were used to study implosion characteristics and stagnated plasma conditions through x-ray yield measurements and spectroscopy. Magnetohydrodynamic (MHD) calculations have suggested that the dopants improved the neutron output through better plasma compression, which has been studied in experiments increasing the dopant fraction. Scaling these experiments, and additional MHD calculations, suggest that {approx}5x10{sup 14} deuterium-deuterium (DD) neutrons could be generated at the 26-MA refurbished Z facility.

  12. Polar-drive implosions on OMEGA and the National Ignition Facility

    SciTech Connect

    Radha, P. B.; Marshall, F. J.; Marozas, J. A.; Shvydky, A.; Gabalski, I.; Boehly, T. R.; Collins, T. J.; Craxton, R. S.; Edgell, D. H.; Epstein, R.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Hohenberger, M.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Petrasso, R. D.; Sangster, T. C.; Skupsky, S.

    2013-04-29

    Polar-drive (PD) experiments on the OMEGA [Boehly et al., Opt. Commun. 133, 495 (1997)] laser are described. Continuous pulse shapes, where a low-power foot is followed by a rise to the main pulse, and triple-picket pulse shapes, where three pickets precede the main pulse, are used to irradiate warm plastic shell capsules. Both of these pulse shapes set the target on a low, ignition-relevant adiabat of ~3.5. The areal density is modeled very well in these implosions indicating that shock timing is well modeled in PD geometry. It is shown that the symmetry can be predictably varied by changing the beam pointings. Symmetry is also well reproduced across the two pulse shapes. Limitations of OMEGA experiments are discussed. Preliminary designs for PD implosion experiments on the NIF, with the goal of addressing ignition-relevant issues for PD, including symmetry are presented.

  13. Polar-drive implosions on OMEGA and the National Ignition Facility

    SciTech Connect

    Radha, P. B.; Marshall, F. J.; Marozas, J. A.; Shvydky, A.; Gabalski, I.; Boehly, T. R.; Collins, T. J. B.; Craxton, R. S.; Edgell, D. H.; Epstein, R.; Froula, D. H.; Goncharov, V. N.; Hohenberger, M.; McKenty, P. W.; Sangster, T. C.; Skupsky, S.; Frenje, J. A.; Petrasso, R. D.; McCrory, R. L.; Meyerhofer, D. D.

    2013-05-15

    Polar-drive (PD) experiments on the OMEGA [Boehly et al., Opt. Commun. 133, 495 (1997)] laser are described. Continuous pulse shapes, where a low-power foot is followed by a rise to the main pulse, and triple-picket pulse shapes, where three pickets precede the main pulse, are used to irradiate warm plastic shell capsules. Both of these pulse shapes set the target on a low, ignition-relevant adiabat of ∼3.5. The areal density is modeled very well in these implosions indicating that shock timing is well modeled in PD geometry. It is shown that the symmetry can be predictably varied by changing the beam pointings. Symmetry is also well reproduced across the two pulse shapes. Limitations of OMEGA experiments are discussed. Preliminary designs for PD implosion experiments on the NIF, with the goal of addressing ignition-relevant issues for PD, including symmetry are presented.

  14. Ion-induced quark-gluon implosion.

    PubMed

    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

  15. On the analysis of shock implosion

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Photoswitches operating upon ns pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Athanassiou, A.; Lakiotaki, K.; Kalyva, M.; Georgiou, S.; Fotakis, C.

    2005-07-01

    We present a potential photoswitch, which undergoes reversible mechanical actuation induced exclusively by photons. The photoswitch is a polymer-based film doped with spiropyran photochromic molecules. It undergoes repeatable mechanical cycles controlled by ns laser pulses of specific wavelengths. The polymer matrix is mechanically activated due to particular photoisomerization processes of the incorporated photochromic molecules, resulting in its contraction and lengthening in a highly controllable manner. We present herein the way that the switching time of this novel photoswitch depends on different laser parameters such as the energy and the repetition rate.

  18. Japanese encephalitis virus NS2B-NS3 protease induces caspase 3 activation and mitochondria-mediated apoptosis in human medulloblastoma cells.

    PubMed

    Yang, Tsuey-Ching; Shiu, Su-Lian; Chuang, Pei-Hsin; Lin, Ying-Ju; Wan, Lei; Lan, Yu-Ching; Lin, Cheng-Wen

    2009-07-01

    Japanese encephalitis virus (JEV) causes severe neurological diseases with a high fatality rate. Clinical, neurophysiological and radiological features of Japanese encephalitis JE patients showed that JEV infection resulted in widespread involvement of the nervous system, including thalamus, basal ganglia, brainstem, cerebellum, cerebral cortex and spinal cord. In this study, we characterized the apoptotic effect of JEV infection and its viral proteins on the TE671 human medulloblastoma cells. JEV replicated in TE671 cells, inducing caspase 3-mediated apoptosis in MOI- and time-dependent manners. Of viral proteins, co-expression of JEV NS3 protease with NS2B cofactor significantly induced higher degrees of apoptosis and triggered higher caspase 3 activities than single expression of E, NS1, NS2B or NS3 protease in human medulloblastoma cells. Moreover, JEV NS2B-NS3 protease induced reduction of mitochondrial membrane potential and release of mitochondrial cytochrome C, which were responsible for the mitochondria-mediated apoptosis. In addition, the production of reactive oxygen species production and activation of ASK1-p38 MAPK signaling pathway might be associated with JEV NS2B-NS3 protease-induced mitochondria-mediated apoptosis. The results demonstrated that the JEV infection and the co-expression of JEV NS3 protease with NS2B cofactor induced caspase 3 activation and mitochondria-mediated apoptosis in human medulloblastoma cells, being valuable insight for cellular and molecular levels of JEV pathogenesis. PMID:19463724

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Numerical investigation on target implosions driven by radiation ablation and shock compression in dynamic hohlraums

    SciTech Connect

    Xiao, Delong; Sun, Shunkai; Zhao, Yingkui; Ding, Ning; Wu, Jiming; Dai, Zihuan; Yin, Li; Zhang, Yang; Xue, Chuang

    2015-05-15

    In a dynamic hohlraum driven inertial confinement fusion (ICF) configuration, the target may experience two different kinds of implosions. One is driven by hohlraum radiation ablation, which is approximately symmetric at the equator and poles. The second is caused by the radiating shock produced in Z-pinch dynamic hohlraums, only taking place at the equator. To gain a symmetrical target implosion driven by radiation ablation and avoid asymmetric shock compression is a crucial issue in driving ICF using dynamic hohlraums. It is known that when the target is heated by hohlraum radiation, the ablated plasma will expand outward. The pressure in the shocked converter plasma qualitatively varies linearly with the material temperature. However, the ablation pressure in the ablated plasma varies with 3.5 power of the hohlraum radiation temperature. Therefore, as the hohlraum temperature increases, the ablation pressure will eventually exceed the shock pressure, and the expansion of the ablated plasma will obviously weaken the shock propagation and decrease its velocity after propagating into the ablator plasma. Consequently, longer time duration is provided for the symmetrical target implosion driven by radiation ablation. In this paper these processes are numerically investigated by changing drive currents or varying load parameters. The simulation results show that a critical hohlraum radiation temperature is needed to provide a high enough ablation pressure to decelerate the shock, thus providing long enough time duration for the symmetric fuel compression driven by radiation ablation.

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

    DOE PAGESBeta

    Stoeckl, C.; Boni, R.; Ehrne, F.; Forrest, C. J.; Glebov, V. Yu.; Katz, J.; Lonobile, D. J.; Magoon, J.; Regan, S. P.; Shoup, III, M. J.; et al

    2016-05-10

    A next-generation neutron temporal diagnostic (NTD) capable of recording high-quality data for the highest anticipated yield cryogenic 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 amore » 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. Furthermore, the measured instrument response includes contributions from the scintillator rise time, optical relay, and streak camera.« less

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

    PubMed

    Stoeckl, C; 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

    2014-11-01

    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 Heα 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. PMID:25430343

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

    SciTech Connect

    Stoeckl, C. 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.

    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.

  4. Numerical investigation on target implosions driven by radiation ablation and shock compression in dynamic hohlraums

    NASA Astrophysics Data System (ADS)

    Xiao, Delong; Sun, Shunkai; Zhao, Yingkui; Ding, Ning; Wu, Jiming; Dai, Zihuan; Yin, Li; Zhang, Yang; Xue, Chuang

    2015-05-01

    In a dynamic hohlraum driven inertial confinement fusion (ICF) configuration, the target may experience two different kinds of implosions. One is driven by hohlraum radiation ablation, which is approximately symmetric at the equator and poles. The second is caused by the radiating shock produced in Z-pinch dynamic hohlraums, only taking place at the equator. To gain a symmetrical target implosion driven by radiation ablation and avoid asymmetric shock compression is a crucial issue in driving ICF using dynamic hohlraums. It is known that when the target is heated by hohlraum radiation, the ablated plasma will expand outward. The pressure in the shocked converter plasma qualitatively varies linearly with the material temperature. However, the ablation pressure in the ablated plasma varies with 3.5 power of the hohlraum radiation temperature. Therefore, as the hohlraum temperature increases, the ablation pressure will eventually exceed the shock pressure, and the expansion of the ablated plasma will obviously weaken the shock propagation and decrease its velocity after propagating into the ablator plasma. Consequently, longer time duration is provided for the symmetrical target implosion driven by radiation ablation. In this paper these processes are numerically investigated by changing drive currents or varying load parameters. The simulation results show that a critical hohlraum radiation temperature is needed to provide a high enough ablation pressure to decelerate the shock, thus providing long enough time duration for the symmetric fuel compression driven by radiation ablation.

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

    PubMed

    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. PMID:27250417

  6. Experimental measurement of Au M-band flux in indirectly-driven double-shell implosions

    SciTech Connect

    Robey, H F; Perry, T S; Park, H S; Amendt, P; Sorce, C M; Compton, S M; Campbell, K M; Knauer, J P

    2005-03-24

    Indirectly-driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility (NIF). In recent double-shell experiments, the inner shell trajectory was shown to exhibit a strong sensitivity to the temporal history of the M-band (2-5 keV) radiation emitted from the Au hohlraum wall. A large time-dependent discrepancy was observed between measurement and simulation of the x-ray flux in this range. In order to better characterize the radiation environment seen in these implosions, an experimental campaign was conducted on the Omega Laser. A number of diagnostics were used to measure both the temporal and spectral nature of the M-band flux. Results were obtained from an absolutely calibrated 12 channel filtered x-ray diode array (Dante) as well as two streaked crystal spectrometers and an absolutely calibrated time-integrated spectrometer (Henway). X-ray backlighting was also used to directly measure the effect of M-band radiation on the trajectory of the inner shell. The data from all diagnostics are shown to be in excellent agreement and provide a consistent picture of the M-band flux. These results are being used to constrain and improve the simulation of hohlraum-generated M-band radiation that will be necessary for the design of future double-shell implosions employing higher-Z inner shells.

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

    NASA Astrophysics Data System (ADS)

    Stoeckl, C.; 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.

    2014-11-01

    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 Heα 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.

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

    SciTech Connect

    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; Stoeckl, C

    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.

  9. Impact of HCV kinetics on treatment outcome differs by the type of real-time HCV assay in NS3/4A protease inhibitor-based triple therapy.

    PubMed

    Ogawa, Eiichi; Furusyo, Norihiro; Murata, Masayuki; Hayashi, Takeo; Shimizu, Motohiro; Mukae, Haru; Toyoda, Kazuhiro; Hotta, Taeko; Uchiumi, Takeshi; Hayashi, Jun

    2016-02-01

    Repeated measurement of the HCV RNA level is essential for properly monitoring treatment efficacy. The aim of this study was to determine the utility of two HCV real-time assays in the evaluation of the impact of hepatitis C virus (HCV) kinetics on the outcome of triple therapy with NS3/4A protease inhibitors (PIs), telaprevir or simeprevir. This study consisted of 171 Japanese patients infected with HCV genotype 1. All 3266 serum samples taken during and post treatment were tested with both the COBAS AmpliPrep/COBAS TaqMan (CAP/CTM) HCV Test v2.0 and the Abbott RealTime (ART) HCV Test. Of the 2597 samples undetectable (lower limit of detection [

  10. Improving cryogenic deuterium–tritium implosion performance on OMEGA

    SciTech Connect

    Sangster, T. C.; Goncharov, V. N.; Betti, R.; Radha, P. B.; Boehly, T. R.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Froula, D. H.; Glebov, Y. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H.; Kessler, T. J.; and others

    2013-05-15

    A flexible direct-drive target platform is used to implode cryogenic deuterium–tritium (DT) capsules on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)]. The goal of these experiments is to demonstrate ignition hydrodynamically equivalent performance where the laser drive intensity, the implosion velocity, the fuel adiabat, and the in-flight aspect ratio (IFAR) are the same as those for a 1.5-MJ target [Goncharov et al., Phys. Rev. Lett. 104, 165001 (2010)] designed to ignite on the National Ignition Facility [Hogan et al., Nucl. Fusion 41, 567 (2001)]. The results from a series of 29 cryogenic DT implosions are presented. The implosions were designed to span a broad region of design space to study target performance as a function of shell stability (adiabat) and implosion velocity. Ablation-front perturbation growth appears to limit target performance at high implosion velocities. Target outer-surface defects associated with contaminant gases in the DT fuel are identified as the dominant perturbation source at the ablation surface; performance degradation is confirmed by 2D hydrodynamic simulations that include these defects. A trend in the value of the Lawson criterion [Betti et al., Phys. Plasmas 17, 058102 (2010)] for each of the implosions in adiabat–IFAR space suggests the existence of a stability boundary that leads to ablator mixing into the hot spot for the most ignition-equivalent designs.

  11. Improving cryogenic deuterium tritium implosion performance on OMEGA

    SciTech Connect

    Sangster, T. C.; Goncharov, V. N.; Betti, R.; Radha, P. B.; Boehly, T. R.; Casey, D. T.; Collins, T. J.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu-Johnson, M.; Glebov, Y. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H.; Kessler, T. J.; Kingsley, C.; Kosc, T. Z.; Knauer, J. P.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; Maximov, A. V.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Petrasso, Richard D.; Regan, S. P.; Seka, W.; Shmayda, W. T.; Short, R. W.; Shvydky, A.; Skupsky, S.; Soures, J. M.; Stoeckl, C.; Theobald, W.; Versteeg, V.; Yaakobi, B.; Zuegel, J. D.

    2013-01-01

    A flexible direct-drive target platform is used to implode cryogenic deuterium–tritium (DT) capsules on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)]. The goal of these experiments is to demonstrate ignition hydrodynamically equivalent performance where the laser drive intensity, the implosion velocity, the fuel adiabat, and the in-flight aspect ratio (IFAR) are the same as those for a 1.5-MJ target [Goncharov et al., Phys. Rev. Lett. 104, 165001 (2010)] designed to ignite on the National Ignition Facility [Hogan et al., Nucl. Fusion 41, 567 (2001)]. The results from a series of 29 cryogenic DT implosions are presented. The implosions were designed to span a broad region of design space to study target performance as a function of shell stability (adiabat) and implosion velocity. Ablation-front perturbation growth appears to limit target performance at high implosion velocities. Target outer-surface defects associated with contaminant gases in the DT fuel are identified as the dominant perturbation source at the ablation surface; performance degradation is confirmed by 2D hydrodynamic simulations that include these defects. A trend in the value of the Lawson criterion [Betti et al., Phys. Plasmas 17, 058102 (2010)] for each of the implosions in adiabat–IFAR space suggests the existence of a stability boundary that leads to ablator mixing into the hot spot for the most ignition-equivalent designs.

  12. Radiative Properties of Argon Gas-Puff Implosions on COBRA

    NASA Astrophysics Data System (ADS)

    Ouart, Nicholas; Qi, Niansheng; de Grouchy, Phil; Shelkovenko, Tatiana; Pikuz, Sergei; Giuliani, John; Dasgupta, Arati; Apruzese, John; Clark, Robert; Hammer, David; Kusse, Bruce

    2015-11-01

    Gas-puff Z-pinch experiments were performed on the 1 MA COBRA pulsed power generator at Cornell University. The gas puffs were injected into the load region from a triple nozzle. The load region had an anode-cathode gap of 2.5 cm. The standard diagnostics on COBRA include time-integrated pinhole cameras, a time-integrated axially resolved x-ray spectrometer, filtered photo-conducting detectors, and time-gated XUV cameras. We will focus mainly on results from pinhole images and x-ray spectra from argon gas puffs including some with a SO2 dopant. The x-ray time-integrated pinhole images feature a tight axially uniform plasma column with a diameter of approximately 1 mm for argon gas implosion. The x-ray spectrometer used mica crystals (2d =19.84 Å) and captured the argon K-shell radiation from different crystal reflections. A 1-D multi-zone argon and sulfur non-LTE kinetics code with radiation transport is used to model the K-shell emission for the purpose of inferring the plasma conditions and the interaction of gas from the inner annulus with the central jet. This work is supported by DOE/NNSA.

  13. High performance capsule implosions on the OMEGA Laser facility with rugby hohlraums

    SciTech Connect

    Robey, H. F.; Amendt, P.; Park, H.-S.; Town, R. P. J.; Milovich, J. L.; Doeppner, T.; Hinkel, D. E.; Wallace, R.; Sorce, C.; Strozzi, D. J.; Philippe, F.; Casner, A.; Caillaud, T.; Landoas, O.; Liberatore, S.; Monteil, M.-C.; Seguin, F.; Rosenberg, M.; Li, C. K.; Petrasso, R.

    2010-05-15

    Rugby-shaped hohlraums have been proposed as a method for x-ray drive enhancement for indirectly driven capsule implosions. This concept has recently been tested in a series of shots on the OMEGA laser facility [T. R. Boehly, D. L. Brown, R. S. Craxton et al., Opt. Commun. 133, 495 (1997)]. In this paper, experimental results are presented comparing the performance of D{sub 2}-filled capsules between standard cylindrical Au hohlraums and rugby-shaped hohlraums. The rugby hohlraums demonstrated 18% more x-ray drive energy as compared with the cylinders, and the high-performance design of these implosions (both cylinder and rugby) also provided {approx_equal}20x more deuterium (DD) neutrons than any previous indirectly driven campaign on OMEGA and {approx_equal}3x more than ever achieved on NOVA [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] implosions driven with nearly twice the laser energy. This increase in performance enables, for the first time, a measurement of the neutron burn history and imaging of the neutron core shapes in an indirectly driven implosion. Previous DD neutron yields had been too low to register this key measurement of capsule performance and the effects of dynamic mix. A wealth of additional data on the fuel areal density from the suite of charged particle diagnostics was obtained on a subset of the shots that used D {sup 3}He rather than D{sub 2} fuel. Comparisons of the experimental results with numerical simulations are shown to be in very good agreement. The design techniques employed in this campaign, e.g., smaller laser entrance holes and hohlraum case-to-capsule ratios, provide added confidence in the pursuit of ignition on the National Ignition Facility [J. D. Lindl, P. Amendt, R. L. Berger et al., Phys. Plasmas 11, 339 (2004)].

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

    SciTech Connect

    Spears, Brian K. Munro, David H.; Sepke, Scott; Caggiano, Joseph; Clark, Daniel; Hatarik, Robert; Kritcher, Andrea; Sayre, Daniel; Yeamans, Charles; Knauer, James; Hilsabeck, Terry; Kilkenny, Joe

    2015-05-15

    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.

  15. K-shell emission trends from 60 to 130 cm/μs stainless steel implosions

    SciTech Connect

    Ampleford, D. J.; Jennings, C. A.; Jones, B.; Hansen, S. B.; Cuneo, M. E.; Coverdale, C. A.; Jones, M. C.; Flanagan, T. M.; Savage, M.; Stygar, W. A.; Lopez, M. R.; Apruzese, J. P.; Thornhill, J. W.; Giuliani, J. L.; Maron, Y.

    2013-10-15

    Recent experiments at the 20 MA Z Accelerator have demonstrated, for the first time, implosion velocities up to 110–130 cm/μs in imploding stainless steel wire arrays. These velocities, the largest inferred in a magnetically driven implosion, lead to ion densities of 2 × 10{sup 20} cm{sup −3} with electron temperatures of ∼5 keV. These plasma conditions have resulted in significant increases in the K-shell radiated output of 5–10 keV photons, radiating powers of >30 TW and yields >80 kJ, making it the brightest laboratory x-ray source in this spectral region. These values represent a doubling of the peak power and a 30% increase in the yield relative to previous studies. The experiments also included wire arrays with slower implosions, which were observed to have lower temperatures and reduced K-shell output. These colder pinches, however, radiated 260 TW in the soft x-ray region, making them one of the brightest soft x-ray sources available.

  16. Collection of solid and gaseous samples to diagnose inertial confinement fusion implosions

    SciTech Connect

    Stoyer, M. A.; Velsko, C. A.; Spears, B. K.; Hicks, D. G.; Hudson, G. B.; Sangster, T. C.; Freeman, C. G.

    2012-02-15

    Collection of representative samples of debris following inertial confinement fusion implosions in order to diagnose implosion conditions and efficacy is a challenging endeavor because of the unique conditions within the target chamber such as unconverted laser light, intense pulse of x-rays, physical chunks of debris, and other ablative effects. We present collection of gas samples following an implosion for the first time. High collection fractions for noble gases were achieved. We also present collection of solid debris samples on flat plate collectors. Geometrical collection efficiencies for Au hohlraum material were achieved and collection of capsule debris (Be and Cu) was also observed. Asymmetric debris distributions were observed for Au and Be samples. Collection of Be capsule debris was higher for solid collectors viewing the capsule through the laser entrance hole in the hohlraum than for solid collectors viewing the capsule around the waist of the hohlraum. Collection of Au hohlraum material showed the opposite pattern: more Au debris was collected around the waist than through the laser entrance hole. The solid debris collectors were not optimized for minimal Cu backgrounds, which limited the conclusions about the symmetry of the Cu debris. The quality of the data limited conclusions on chemical fractionation effects within the burning, expanding, and then cooling plasma.

  17. Collection of solid and gaseous samples to diagnose inertial confinement fusion implosions.

    PubMed

    Stoyer, M A; Velsko, C A; Spears, B K; Hicks, D G; Hudson, G B; Sangster, T C; Freeman, C G

    2012-02-01

    Collection of representative samples of debris following inertial confinement fusion implosions in order to diagnose implosion conditions and efficacy is a challenging endeavor because of the unique conditions within the target chamber such as unconverted laser light, intense pulse of x-rays, physical chunks of debris, and other ablative effects. We present collection of gas samples following an implosion for the first time. High collection fractions for noble gases were achieved. We also present collection of solid debris samples on flat plate collectors. Geometrical collection efficiencies for Au hohlraum material were achieved and collection of capsule debris (Be and Cu) was also observed. Asymmetric debris distributions were observed for Au and Be samples. Collection of Be capsule debris was higher for solid collectors viewing the capsule through the laser entrance hole in the hohlraum than for solid collectors viewing the capsule around the waist of the hohlraum. Collection of Au hohlraum material showed the opposite pattern: more Au debris was collected around the waist than through the laser entrance hole. The solid debris collectors were not optimized for minimal Cu backgrounds, which limited the conclusions about the symmetry of the Cu debris. The quality of the data limited conclusions on chemical fractionation effects within the burning, expanding, and then cooling plasma. PMID:22380089

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. PMID:12083190

  1. Imaging of High-Energy X-Ray Emission from Cryogenic Thermonuclear Fuel Implosions on the NIF

    SciTech Connect

    Ma, T

    2012-05-01

    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 spectrally resolved time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered targets. Using bremsstrahlung assumptions, the measured absolute x-ray brightness allows for the inference of electron temperature, electron density, hot spot mass, mix mass, and pressure. Current inertial confinement fusion (ICF) experiments conducted on the National Ignition Facility (NIF) seek to indirectly drive a spherical implosion, compressing and igniting a deuterium-tritium fuel. This DT fuel capsule is cryogenically prepared as a solid ice layer surrounded by a low-Z ablator material. Ignition will occur when the hot spot approaches sufficient temperature ({approx}3-4 keV) and {rho}R ({approx}0.3 g/cm{sup 2}) such that alpha deposition can further heat the hot spot and generate a self-sustaining burn wave. During the implosion, the fuel mass becomes hot enough to emit large amounts of x-ray radiation, the spectra and spatial variation of which contains key information that can be used to evaluate the implosion performance. The Ross filter diagnostic employs differential filtering to provide spectrally resolved, time-integrated, absolute x-ray self-emission images of the imploded core of cryogenic layered targets.

  2. First Beryllium Capsule implosions on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Kline, John

    2015-11-01

    The first implosion experiments using Beryllium (Be) capsules have been conducted at the National Ignition Facility (NIF) to confirm the superior ablation properties and to elucidate possible Be-ablator issues. 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 and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs have measured the laser energy backscatter, shock velocities, 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. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable, if not better, for Be than for 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 demonstrate good coupling of laser energy to the target and control over the implosion shape indicating the feasibility of Be capsule design opening up a larger design space for ICF. In addition, this data, together with data for low fill-density hohlraum performance, indicates 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.

  3. Probing high areal-density cryogenic deuterium-tritium implosions using downscattered neutron spectra measured by the magnetic recoil spectrometera)

    NASA Astrophysics Data System (ADS)

    Frenje, J. A.; Casey, D. T.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Glebov, V. Yu.; Radha, P. B.; Sangster, T. C.; Meyerhofer, D. D.; Hatchett, S. P.; Haan, S. W.; Cerjan, C. J.; Landen, O. L.; Fletcher, K. A.; Leeper, R. J.

    2010-05-01

    For the first time high areal-density (ρR) cryogenic deuterium-tritium (DT) implosions have been probed using downscattered neutron spectra measured with the magnetic recoil spectrometer (MRS) [J. A. Frenje et al., Rev. Sci. Instrum. 79, 10E502 (2008)], recently installed and commissioned on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The ρR data obtained with the MRS have been essential for understanding how the fuel is assembled and for guiding the cryogenic program at the Laboratory for Laser Energetics (LLE) to ρR values up to ˜300 mg/cm2. The ρR data obtained from well-established charged particle spectrometry techniques [C. K. Li et al., Phys. Plasmas 8, 4902 (2001)] were used to authenticate the MRS data for low-ρR plastic capsule implosions, and the ρR values inferred from these techniques are in excellent agreement, indicating that the MRS technique provides high-fidelity data. Recent OMEGA-MRS data and Monte Carlo simulations have shown that the MRS on the NIF [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] will meet most of the absolute and relative requirements for determining ρR, ion temperature (Ti) and neutron yield (Yn) in both low-yield, tritium-rich, deuterium-lean, hydrogen-doped implosions and high-yield DT implosions.

  4. T-T Neutron Spectrum from Inertial Confinement Implosions

    NASA Astrophysics Data System (ADS)

    Caggiano, Joseph; Sayre, Daniel; Brune, Carl; Gatu Johnson, Maria; McNabb, Dennis; Bacher, Andrew

    2014-03-01

    Measurements of the T(t , 2 n) α fusion reaction (TT) have been conducted using high-purity (~99 percent) tritium, gas-filled glass capsules in inertial confinement fusion implosions. In these experiments, which were conducted at both the NIF and the OMEGA laser facilities, spectral measurements of the TT neutrons were carried out using two well-established instruments: the neutron-time-of-flight (nTOF) and the magnet-based Magnetic Recoil Spectrometer (MRS). The resolutions of these systems were improved significantly for the nTOF facility by using a crystal with much faster decay time and for the MRS by using a thinner, more uniform CD2 recoil foil. At OMEGA, charged particle energy spectra were also measured using a magnetic charged particle spectrometer and the Thompson Parabola Ion Energy spectrometer. These measurements at reactant central-mass energies in the range of 10-30 keV can be used to study the TT reaction mechanism near astrophysical energies. This work was reported at the 2013 APS April meeting, where we used basic R-matrix line shapes. Since then we have updated and improved the fitting method by including the proper quantum interferences from fermion symmetry and decay channels. The implications of these effects on our understanding of the spectrum also will be discussed.

  5. T-T Neutron Spectrum from Inertial Confinement Implosions

    NASA Astrophysics Data System (ADS)

    Caggiano, Joseph; Gatu Johnson, Maria; Bacher, Andrew; McNabb, Denns

    2013-04-01

    Measurements of the T(2n,)^4He reaction (TT) have been conducted using high-purity tritium, gas-filled capsules in inertial confinement fusion (ICF) implosions. At the OMEGA laser facility, TT neutron spectra were measured using two instruments: the neutron-time-of-flight (nTOF) facility and the Magnetic Recoil Spectrometer (MRS) facility. The resolutions of these systems were improved for nTOF by using a crystal with much faster decay time and for MRS by using a thinner, more uniform CD2 recoil foil. Measurements at c.m. energies of 10-30 keV can be used to study the TT three-body reaction mechanism near astrophysical energies. With both nTOF and MRS, we observe a small, narrow peak starting at the 9.44 MeV endpoint, corresponding to the n + ^5He (g.s.) reaction channel. Most of the TT reaction proceeds through other reaction channels which produce broad, continuous neutron spectra in the range 0 - 9.5 MeV. Implications for ICF experiments at the National Ignition Facility will be discussed. Work in collaboration with J. A. Frenje, D. T. Casey, M. J.-E. Manuel, N. Sinenian, A. B. Zylstra, F. H. Seguin, C. K. Li, R. D. Petrasso, V. Yu Glebov, P. B. Radha, D. D. Meyerhofer, T. C. Sangster, P. A. Amendt, R. Hatarik, D. B. Sayre, J. R. Rygg, H. W. Herrmann and Y. H. Kim.

  6. Specific features of the structure of the Z-pinch emitting region formed during the implosion of a foam-wire load at the ANGARA-5-1 facility

    SciTech Connect

    Mitrofanov, K. N. Grabovski, E. V.; Gritsuk, A. N.; Laukhin, Ya. N.; Aleksandrov, V. V.; Oleinik, G. M.; Medovshchikov, S. F.; Shevel'ko, A. P.

    2013-01-15

    Results are presented from experimental studies of the structure of the compressed plasma of a Z-pinch produced during the implosion of a foam-wire load at the current of up to 3 MA. The foam-wire load consisted of two nested cylindrical cascades, one of which was a solid or hollow cylinder made of low-density agar-agar foam, while the other was a wire array. The wall thickness of a hollow foam cylinder was 100-200 {mu}m. The images of the pinch and its spectrum obtained with the help of multiframe X-ray cameras and a grazing incidence spectrograph with a spatial resolution were analyzed. Data on the spatial structure of the emitting regions and the soft X-ray (SXR) spectrum of the Z-pinch in the final stage of compression of a foam-wire load were obtained. The implosion modes characterized by the formation of hot regions during implosion of such loads were revealed. The characteristic scale lengths of the hot regions were determined. It is shown that the energy distribution of SXR photons in the energy range from 80 eV to 1 keV forms the spatial structure of Z-pinch images recorded during the implosion of foam-wire loads. It is revealed that the spectral density of SXR emission in the photon energy range of 300-600 eV from hot Z-pinch regions exceeds the spectral density of radiation from the neighboring Z-pinch regions by more than one order of magnitude. Groups of lines related to the absorption and emission of radiation by atoms and multicharged ions of carbon and oxygen in the outer foam cascade of a foam-wire load were recorded for the first time by analyzing the spatial distribution of the SXR spectra of multicharged ions of the Z-pinch. The groups of absorption lines of ions (C III, O III, O IV, and O VI) corresponding to absorption of SXR photons in the Z-pinch of a tungsten wire array, which served as the inner cascade of a foam-wire load, were identified. The plasma electron temperature measured from the charge composition of carbon and oxygen ions in

  7. Implosion dynamics in direct-drive experiments

    NASA Astrophysics Data System (ADS)

    Michel, D. T.; Craxton, R. S.; Davis, A. K.; Epstein, R.; Glebov, V. Yu; Goncharov, V. N.; Hu, S. X.; Igumenshchev, I. V.; Meyerhofer, D. D.; Radha, P. B.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Froula, D. H.

    2015-01-01

    Increasing the ablation pressure is a path to achieving cryogenic implosion performance on the OMEGA laser that will hydrodynamically scale to ignition on the National Ignition Facility. An increased ablation pressure will allow a more-massive shell (i.e. thicker and more hydrodynamically stable) and a higher adiabat to achieve ignition-relevant velocities (>3.5 × 107 cm s-1), areal densities (>300 mg cm-2) and hot-spot pressures (>100 Gbar). Two approaches have demonstrated increased ablation pressure: (1) a target design is shown that uses a Be ablator to increase the hydrodynamic efficiency, resulting in a ˜10% increase in the ablation pressure, in comparison to a CH ablator; (2) reducing the beam size is shown to recover all of the ablation pressure lost to cross-beam energy transfer (CBET), i.e. the ablation pressure calculated without CBET, but the degraded illumination uniformity reduces the integrated target performance. The hydrodynamic efficiency is measured for the current cryogenic design, multiple ablator material design and CH capsule designs with various beam focal-spot sizes. In each case, an excellent agreement is observed with 1D hydrodynamic simulations that include CBET and nonlocal heat-transport models.

  8. Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions

    SciTech Connect

    Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; Rinderknecht, Hans G.; Rosenberg, Michael J.; Albright, B. J.; Simakov, Andrei N.; Sio, Hong; Zylstra, Alex B.; Johnson, Maria Gatu; Séguin, Fredrick H.; Frenje, Johan A.; Li, C. K.; Petrasso, Richard D.; Higdon, David M.; Srinivasan, Gowri; Glebov, Vladimir Yu.; Stoeckl, Christian; Seka, Wolf; Sangster, T. Craig

    2015-05-19

    “Reduced” (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method described here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple approach

  9. Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions

    DOE PAGESBeta

    Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; Rinderknecht, Hans G.; Rosenberg, Michael J.; Albright, B. J.; Simakov, Andrei N.; Sio, Hong; Zylstra, Alex B.; Johnson, Maria Gatu; et al

    2015-05-19

    “Reduced” (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method describedmore » here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple

  10. Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions

    NASA Astrophysics Data System (ADS)

    Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; Rinderknecht, Hans G.; Rosenberg, Michael J.; Albright, B. J.; Simakov, Andrei N.; Sio, Hong; Zylstra, Alex B.; Gatu Johnson, Maria; Séguin, Fredrick H.; Frenje, Johan A.; Li, C. K.; Petrasso, Richard D.; Higdon, David M.; Srinivasan, Gowri; Glebov, Vladimir Yu.; Stoeckl, Christian; Seka, Wolf; Sangster, T. Craig

    2015-05-01

    "Reduced" (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method described here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple approach

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

    SciTech Connect

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

    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.

  12. Explosion-Induced Implosions of Cylindrical Shell Structures

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.

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

    NASA Astrophysics Data System (ADS)

    Wilson, D. C.; Aragonez, R. J.; Archuleta, T. N.; Atkinson, D. P.; Barrios, M. A.; Batha, S. H.; Bower, D. E.; Bradley, D. K.; Buckles, R. A.; Clark, D. D.; Clark, D. S.; Clark, D. J.; Cradick, J. R.; Danly, C. R.; Day, R. D.; Dzenitis, J. M.; Drury, O. B.; Fatherley, V. E.; Felker, B.; Finch, J. P.; Fittinghoff, D. N.; Frank, M.; Gallegos, R. A.; Garcia, F. P.; Glenn, S. M.; Grim, G. P.; Guler, N.; Hsu, A. H.; Izumi, N.; Jaramillo, S. A.; Jones, O. S.; Kaufman, M. I.; Kilkenny, J. D.; Kyrala, G. A.; Le Pape, S.; Liddick, S. N.; Loomis, E. N.; Lutz, S. S.; Ma, T.; Mackinnon, A. J.; Malone, R. M.; Mares, D.; Marinak, M. M.; Martinson, D. D.; McKenty, P.; Meezan, N. S.; Merrill, F. E.; Moran, M. J.; Morgan, G. L.; Munson, C.; Munro, D. H.; Murphy, T. J.; Oertel, J. A.; Patel, M. V.; Polk, P. J.; Regan, S.; Roberson, G. P.; Schmidt, D. W.; Sepke, S. M.; Spears, B. K.; Tommasini, R.; Town, R.; Traille, A.; Tregillis, I. L.; Valdez, A. C.; Volegov, P. L.; Wang, T.-S. F.; Weiss, P.; Wilde, C. H.; Wilke, M. D.

    2013-11-01

    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.

  14. An initial assessment of three-dimensional polar direct drive capsule asymmetries for implosions at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Krasheninnikova, Natalia S.; Finnegan, Sean M.; Schmitt, Mark J.

    2012-01-01

    The National Ignition Facility (NIF) provides a unique opportunity to study implosion physics with nuclear yield. The use of polar direct drive (PDD) [A. M. Cok, R. S. Craxton, and P. W. McKenty, Phys. Plasmas 15, 082705 (2008)] provides a simple platform for the experimental studies without expensive optics upgrades to NIF. To determine the optimum PDD laser pointing geometry on NIF and provide a baseline for validating inertial confinement fusion codes against experiments for symmetric and asymmetric implosions, computer simulations using the 3D radiation-hydrodynamics code hydra [M. M. Marinak, R. E. Tipton, O. L. Landen, T. J. Murphy, P. Amendt, S. W. Haan, S. P. Hatchett, C. J. Keane, R. McEachern, and R. Wallace, Phys. Plasmas 3, 2070 (1996)] were preformed. The upper hemisphere of a DT-filled CH capsule was imploded by 96 NIF beams in a PDD configuration. Asymmetries in both polar and equatorial directions around the capsule were observed, with the former dominating the latter. Analysis of the simulation results indicates that the lack of symmetry in the initial power density profile (during the first 200 ps of the implosion) is a primary cause of late-time asymmetry in the implosion as well as decreased yield. By adjusting the laser pointings, the symmetry and total neutron yield were improved. Simulations with dropped quads (four of the NIF laser system's 192 beamlines) without repointing worsen the overall symmetry by a factor of 10 (with respect to rms radial variation around the capsule) and reduce neutron yield by a factor of 2. Both of these degraded implosion characteristics are restored by azimuthal repointing of the remaining quads.

  15. Towards a Phonetic Explanation for Universal Preferences in Implosives and Ejections.

    ERIC Educational Resources Information Center

    Javkin, Hector

    Two possible explanations based on elementary facts of physics are suggested for the universal preference for place of articulation of implosives and ejectives. Languages show a preference for ejectives in the order: velar, alveolar, and labial while implosives occur most often in the opposite order. A language will only have velar implosives if…

  16. Characterization of the magnetization reversal of perpendicular Nanomagnetic Logic clocked in the ns-range

    NASA Astrophysics Data System (ADS)

    Ziemys, Grazvydas; Trummer, Christian; Gamm, Stephan Breitkreutz-v.; Eichwald, Irina; Schmitt-Landsiedel, Doris; Becherer, Markus

    2016-05-01

    We have investigated the magnetization reversal of fabricated Co/Pt nanomagnets with perpendicular anisotropy within a wide range of magnetic field pulse widths. This experiment covers the pulse lengths from 700 ms to 20 ns. We observed that the commonly used Arrhenius model fits very well the experimental data with a single parameter set for pulse times above 100 ns (tp > 100 ns). However, below 100 ns (tp < 100 ns), a steep increase of the switching field amplitude is observed and the deviation from the Arrhenius model becomes unacceptable. For short pulse times the model can be adjusted by the reversal time term for the dynamic switching field which is only dependent on the pulse amplitude and not on temperature anymore. Precise modeling of the magnetization reversal in the sub-100 ns-range is crucially important to ensure reliable operation in the favored GHz-range as well as to explore and design new kinds of Nanomagnetic Logic circuits and architectures.

  17. Exploration of kinetic and multiple-ion-fluids effects in D3He and T3He gas-filled ICF implosions using multiple nuclear reaction histories

    NASA Astrophysics Data System (ADS)

    Sio, Hong; Rinderknecht, Hans; Rosenberg, Michael; Zylstra, Alex; Séguin, Fredrick; Gatu Johnson, Maria; Li, Chikang; Petrasso, Richard; Hoffman, Nelson; Kagan, Krigory; Molvig, Kim; Amendt, Peter; Bellei, Claudio; Wilks, Scott; Stoeckl, Christian; Glebov, Vladimir; Betti, Riccardo; Sangster, Thomas; Katz, Joseph

    2014-10-01

    To explore kinetic and multi-ion-fluid effects in D3He and T3He gas-filled shock-driven implosions, multiple nuclear reaction histories were measured using the upgraded Particle Temporal Diagnostic (PTD) on OMEGA. For D3He gas-filled implosions, the relative timing of the DD and D3He reaction histories were measured with 20 ps precision. For T3He gas-filled implosions (with 1-2% deuterium), the relative timing of the DT and D3He reaction histories were measured with 10 ps precision. The observed differences between the reaction histories on these two OMEGA experiments are contrasted to 1-D single-ion hydro simulations for different gas-fill pressure and gas mixture. This work is supported in part by the U.S. DOE, LLNL, LLE, and NNSA SSGF.

  18. Uniform fuel target implosion in heavy ion inertial fusion

    NASA Astrophysics Data System (ADS)

    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.

  19. Strong Coupling and Degeneracy Effects in Inertial Confinement Fusion Implosions

    SciTech Connect

    Hu, S.X.; Militzer, B.; Goncharov, V.N.; Skupsky, S.

    2010-06-10

    Accurate knowledge about the equation of state (EOS) of deuterium is critical to inertial confinement fusion (ICF). Low-adiabat ICF implosions routinely access strongly coupled and degenerate plasma conditions. Using the path integral Monte Carlo method, we have derived a first-principles EOS (FPEOS) table of deuterium. It is the first ab initio EOS table which completely covers typical ICF implosion trajectory in the density and temperature ranges of rho = 0.002–1596 g/cm^3 and T = 1.35 eV–5.5 keV. Discrepancies in internal energy and pressure have been found in strongly coupled and degenerate regimes with respect to SESAME EOS. Hydrodynamics simulations of cryogenic ICF implosions using the FPEOS table have indicated significant differences in peak density, areal density, and neutron yield relative to SESAME simulations.

  20. Self-similar Isochoric Implosions for Fast Ignition

    NASA Astrophysics Data System (ADS)

    Clark, Daniel

    2005-10-01

    Fast Ignition (FI) exploits the ignition of a dense, uniform fuel assembly by an external energy source to achieve high gain. However, in conventional ICF implosions, 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 studied by Guderley [Luftfahrtforschung 19, 302 (1942).] and later Meyer-ter-Vehn & Schalk [Z. Naturforsch. 37a, 955 (1982).] may be employed to implode dense, uniform fuel assemblies with minimal energy wastage in forming a hotspot. The connection to "realistic" (i.e., non-self-similar) implosion schemes using laser or X-ray drive is also investigated.

  1. Human Bocavirus NS1 and NS1-70 Proteins Inhibit TNF-α-Mediated Activation of NF-κB by targeting p65

    PubMed Central

    Liu, Qingshi; Zhang, Zhenfeng; Zheng, Zhenhua; Zheng, Caishang; Liu, Yan; Hu, Qinxue; Ke, Xianliang; Wang, Hanzhong

    2016-01-01

    Human bocavirus (HBoV), a parvovirus, is a single-stranded DNA etiologic agent causing lower respiratory tract infections in young children worldwide. Nuclear factor kappa B (NF-κB) transcription factors play crucial roles in clearance of invading viruses through activation of many physiological processes. Previous investigation showed that HBoV infection could significantly upregulate the level of TNF-α which is a strong NF-κB stimulator. Here we investigated whether HBoV proteins modulate TNF-α–mediated activation of the NF-κB signaling pathway. We showed that HBoV NS1 and NS1-70 proteins blocked NF-κB activation in response to TNF-α. Overexpression of TNF receptor-associated factor 2 (TRAF2)-, IκB kinase alpha (IKKα)-, IκB kinase beta (IKKβ)-, constitutively active mutant of IKKβ (IKKβ SS/EE)-, or p65-induced NF-κB activation was inhibited by NS1 and NS1-70. Furthermore, NS1 and NS1-70 didn’t interfere with TNF-α-mediated IκBα phosphorylation and degradation, nor p65 nuclear translocation. Coimmunoprecipitation assays confirmed the interaction of both NS1 and NS1-70 with p65. Of note, NS1 but not NS1-70 inhibited TNF-α-mediated p65 phosphorylation at ser536. Our findings together indicate that HBoV NS1 and NS1-70 inhibit NF-κB activation. This is the first time that HBoV has been shown to inhibit NF-κB activation, revealing a potential immune-evasion mechanism that is likely important for HBoV pathogenesis. PMID:27329558

  2. Human Bocavirus NS1 and NS1-70 Proteins Inhibit TNF-α-Mediated Activation of NF-κB by targeting p65.

    PubMed

    Liu, Qingshi; Zhang, Zhenfeng; Zheng, Zhenhua; Zheng, Caishang; Liu, Yan; Hu, Qinxue; Ke, Xianliang; Wang, Hanzhong

    2016-01-01

    Human bocavirus (HBoV), a parvovirus, is a single-stranded DNA etiologic agent causing lower respiratory tract infections in young children worldwide. Nuclear factor kappa B (NF-κB) transcription factors play crucial roles in clearance of invading viruses through activation of many physiological processes. Previous investigation showed that HBoV infection could significantly upregulate the level of TNF-α which is a strong NF-κB stimulator. Here we investigated whether HBoV proteins modulate TNF-α-mediated activation of the NF-κB signaling pathway. We showed that HBoV NS1 and NS1-70 proteins blocked NF-κB activation in response to TNF-α. Overexpression of TNF receptor-associated factor 2 (TRAF2)-, IκB kinase alpha (IKKα)-, IκB kinase beta (IKKβ)-, constitutively active mutant of IKKβ (IKKβ SS/EE)-, or p65-induced NF-κB activation was inhibited by NS1 and NS1-70. Furthermore, NS1 and NS1-70 didn't interfere with TNF-α-mediated IκBα phosphorylation and degradation, nor p65 nuclear translocation. Coimmunoprecipitation assays confirmed the interaction of both NS1 and NS1-70 with p65. Of note, NS1 but not NS1-70 inhibited TNF-α-mediated p65 phosphorylation at ser536. Our findings together indicate that HBoV NS1 and NS1-70 inhibit NF-κB activation. This is the first time that HBoV has been shown to inhibit NF-κB activation, revealing a potential immune-evasion mechanism that is likely important for HBoV pathogenesis. PMID:27329558

  3. Measurements of collective fuel velocities in deuterium-tritium exploding pusher and cryogenically layered deuterium-tritium implosions on the NIF

    SciTech Connect

    Gatu Johnson, M.; Casey, D. T.; Frenje, J. A.; Li, C.-K.; Seguin, F. H.; Petrasso, R. D.; Ashabranner, R.; Bionta, R.; LePape, S.; McKernan, M.; Mackinnon, A.; Kilkenny, J. D.; Knauer, J.; Sangster, T. C.

    2013-04-15

    For the first time, quantitative measurements of collective fuel velocities in Inertial Confinement Fusion implosions at the National Ignition Facility are reported. Velocities along the line-of-sight (LOS) of the Magnetic Recoil neutron Spectrometer (MRS), positioned close to the equator (73 Degree-Sign -324 Degree-Sign ), were inferred from the measured mean energy of the deuterium-tritium (DT)-primary neutron peak. Substantial mean energy shifts up to 113 {+-} 16 keV were observed in DT gas-filled exploding-pusher implosions, driven in a polar-direct drive configuration, which corresponds to bulk fuel velocities up to 210 {+-} 30 km/s. In contrast, only marginal bulk fuel velocities along the MRS LOS were observed in cryogenically layered DT implosions. Integrated analysis of data from a large number of cryogenically layered implosions has recently identified a deficit in achieved hot-spot energy of {approx}3 kJ for these implosions [C. Cerjan et al., Phys. Plasmas (2013)]. One hypothesis that could explain this missing energy is a collective, directional fuel velocity of {approx}190 km/s. As only marginal bulk fuel velocities are observed in the MRS data, this might indicate that turbulent or radial flows would be a likely explanation for the missing energy. However, a directional velocity close to perpendicular to the MRS LOS cannot be ruled out.

  4. First beryllium capsule implosions on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    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.

  5. Diagnosing radiative shocks from deuterium and tritium implosions on NIFa)

    NASA Astrophysics Data System (ADS)

    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.

  6. Effect of Beam Smoothing and Pulse Shape on the Implosion of DD-Filled CH Shell Targets on OMEGA

    NASA Astrophysics Data System (ADS)

    Delettrez, J. A.; Glebov, V. Yu.; Marshall, F. J.; Stoeckl, C.; Yaakobi, B.; Meyerhofer, D. D.

    1999-11-01

    Over the past two years several implosion experiments were carried out on the 60-beam OMEGA laser in which DD-filled CH shells (some with a CHTi layer imbedded) were irradiated with various laser pulse shapes and smoothing conditions. Target CH shell thicknesses varied from 20 μm to 27 μm with DD-fill variations from 3 to 20 atm, sometimes mixed with ^3He. Two pulse shapes---a 1-ns square pulse and a 2.5-ns pulse with a 10%, 1-ns foot, with and without SSD---provide several levels of laser imprint. Diagnostics include measured neutron yields, fuel ion temperatures, fuel ρR, and shell ρR. Simulations for these experimental conditions were carried out with the 2-D hydrocode ORCHID. The results are compared with the experimental results. The degradation of target performance due to laser nonuniformity is analyzed by comparing the 2-D results with those of 1-D simulations. The effects of pulse shape, target thickness, convergence ratio, and smoothing are presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460, the University of Rochester, and the New York State Energy Research and Development Authority.

  7. Studies of solid liner stability in electromagnetic implosions

    SciTech Connect

    Atchison, W.L.; Faehl, R.J.; Rienovsky, R.E.; Morgan, D.

    1998-12-31

    The authors have conducted a series of experiments involving electromagnetic implosion of solid aluminum liners on the Pegasus II capacitor bank. These experiments consisted of liners on which single wavelength perturbations had been cut into the outer surface. Typical liner thickness was 400 mm and the usual material was the 1100 aluminum alloy. This alloy is relatively soft with a high conductivity. Recently comparisons have been made with harder but more resistive alloys. The sinusoidal perturbations ranged in amplitude between 10--100 mm and their wavelength between 0.5 and 2.0 mm. Radiographs of the imploding liners showed that the initial perturbations grew to amplitudes of 2000--4000 mm before completely rupturing and injecting flux into the region interior to the liner. Throughout the growth of the perturbations, there was virtually no coupling to other wavelengths. Even after liner disruption, the series of disk-like structures that resulted remained at the same scale length until impact with a center conductor. Two-dimensional MHD simulations of these experiments with the high conductivity Al-1100 alloy have yielded consistently good agreement, both qualitatively and quantitatively. Because the magnetic diffusion time in this alloy is comparable to or longer than the growth time, they find that the dynamics can be approximated by theories of Rayleigh-Taylor instability for which strength has been included. Recently, the authors have conducted two experiments with other aluminum alloys. These alloys have a significantly higher tensile yield strength than the 1100 alloy, but also somewhat high resistivity. Because the magnetic diffusion, ohmic heating, and loss of strength all occur on shorter times than does the growth, the forces acting on the liner are more distributed throughout the liner thickness than on the previous experiments. Qualitatively different features have been observed in the radiographs of these experiments. Two-dimensional MHD

  8. National Ignition Campaign (NIC) Precision Tuning Series Shock Timing Experiments

    SciTech Connect

    Robey, H F; Celliers, P M

    2011-07-19

    A series of precision shock timing experiments have been performed on NIF. These experiments continue to adjust the laser pulse shape and employ the adjusted cone fraction (CF) in the picket (1st 2 ns of the laser pulse) as determined from the re-emit experiment series. The NIF ignition laser pulse is precisely shaped and consists of a series of four impulses, which drive a corresponding series of shock waves of increasing strength to accelerate and compress the capsule ablator and fuel layer. To optimize the implosion, they tune not only the strength (or power) but also, to sub-nanosecond accuracy, the timing of the shock waves. In a well-tuned implosion, the shock waves work together to compress and heat the fuel. For the shock timing experiments, a re-entrant cone is inserted through both the hohlraum wall and the capsule ablator allowing a direct optical view of the propagating shocks in the capsule interior using the VISAR (Velocity Interferometer System for Any Reflector) diagnostic from outside the hohlraum. To emulate the DT ice of an ignition capsule, the inside of the cone and the capsule are filled with liquid deuterium.

  9. Hybrid simulations of Z-Pinches in support of wire array implosion experiments at NTF.

    SciTech Connect

    Sotnikov, Vladimir Isaakovich; Oliver, Bryan Velten; Ivanov, Vladimir V.; LePell, Paul David; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Travnicek, P.; Deeney, Christopher; Hellinger, P.; Jones, B.; Leboeuf, J. N.; Cowan, Thomas E.; Safronova, Alla S.

    2005-07-01

    Three-dimensional hybrid simulation of a plasma current-carrying column reveal two different regimes of sausage and kink instability development. In the first regime, with small Hall parameter, development of instabilities leads to the appearance of large-scale axial perturbations and eventually to bending of the plasma column. In the second regime, with a four-times-larger Hall parameter, small-scale perturbations dominate and no bending of the plasma column is observed. Simulation results are compared with laser probing experimental data obtained during wire array implosions on the Zebra pulse power generator at the Nevada Terawatt Facility.

  10. Observation of a reflected shock in an indirectly driven spherical implosion at the national ignition facility.

    PubMed

    Le Pape, S; Divol, L; Berzak Hopkins, L; Mackinnon, A; Meezan, N B; Casey, D; Frenje, J; Herrmann, H; McNaney, J; Ma, T; Widmann, K; Pak, A; Grimm, G; Knauer, J; Petrasso, R; Zylstra, A; Rinderknecht, H; Rosenberg, M; Gatu-Johnson, M; Kilkenny, J D

    2014-06-01

    A 200  μm radius hot spot at more than 2 keV temperature, 1  g/cm^{3} density has been achieved on the National Ignition Facility using a near vacuum hohlraum. The implosion exhibits ideal one-dimensional behavior and 99% laser-to-hohlraum coupling. The low opacity of the remaining shell at bang time allows for a measurement of the x-ray emission of the reflected central shock in a deuterium plasma. Comparison with 1D hydrodynamic simulations puts constraints on electron-ion collisions and heat conduction. Results are consistent with classical (Spitzer-Harm) heat flux. PMID:24949774

  11. Observation of a Reflected Shock in an Indirectly Driven Spherical Implosion at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Le Pape, S.; Divol, L.; Berzak Hopkins, L.; Mackinnon, A.; Meezan, N. B.; Casey, D.; Frenje, J.; Herrmann, H.; McNaney, J.; Ma, T.; Widmann, K.; Pak, A.; Grimm, G.; Knauer, J.; Petrasso, R.; Zylstra, A.; Rinderknecht, H.; Rosenberg, M.; Gatu-Johnson, M.; Kilkenny, J. D.

    2014-06-01

    A 200 μm radius hot spot at more than 2 keV temperature, 1 g/cm3 density has been achieved on the National Ignition Facility using a near vacuum hohlraum. The implosion exhibits ideal one-dimensional behavior and 99% laser-to-hohlraum coupling. The low opacity of the remaining shell at bang time allows for a measurement of the x-ray emission of the reflected central shock in a deuterium plasma. Comparison with 1D hydrodynamic simulations puts constraints on electron-ion collisions and heat conduction. Results are consistent with classical (Spitzer-Harm) heat flux.

  12. Experimental measurement of Au M-band flux in indirectly driven double-shell implosions

    SciTech Connect

    Robey, H.F.; Perry, T.S.; Park, H.-S.; Amendt, P.; Sorce, C.M.; Compton, S.M.; Campbell, K.M.; Knauer, J.P.

    2005-07-15

    Indirectly driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)]. In recent double-shell experiments, the inner shell trajectory was shown to exhibit a strong sensitivity to the temporal history of the M-band (2-5 keV) radiation emitted from the Au hohlraum wall. A large time-dependent discrepancy was observed between measurement and simulation of the x-ray flux in this range. In order to better characterize the radiation environment seen in these implosions, an experimental campaign was conducted on the Omega laser. A number of diagnostics were used to measure both the temporal and spectral nature of the M-band flux. Results were obtained from an absolutely calibrated 12-channel filtered x-ray diode array (Dante) as well as two streaked crystal spectrometers and an absolutely calibrated time-integrated spectrometer (Henway). X-ray backlighting was also used to directly measure the effect of M-band radiation on the trajectory of the inner shell. The data from all diagnostics are shown to be in excellent agreement and provide a consistent picture of the M-band flux. These results are being used to constrain and improve the simulation of hohlraum-generated M-band radiation that will be necessary for the design of future double-shell implosions employing higher-Z inner shells.

  13. Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive.

    PubMed

    Casey, D T; Milovich, J L; Smalyuk, V A; Clark, D S; Robey, H F; Pak, A; MacPhee, A G; Baker, K L; Weber, C R; Ma, T; Park, H-S; Döppner, T; Callahan, D A; Haan, S W; Patel, P K; Peterson, J L; Hoover, D; Nikroo, A; Yeamans, C B; Merrill, F E; Volegov, P L; Fittinghoff, D N; Grim, G P; Edwards, M J; Landen, O L; Lafortune, K N; MacGowan, B J; Widmayer, C C; Sayre, D B; Hatarik, R; Bond, E J; Nagel, S R; Benedetti, L R; Izumi, N; Khan, S; Bachmann, B; Spears, B K; Cerjan, C J; Gatu Johnson, M; Frenje, J A

    2015-09-01

    Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR>1  g/cm(2). This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition. PMID:26382681

  14. Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive

    SciTech Connect

    Casey, D. T.; Milovich, J. L.; Smalyuk, V. A.; Clark, D. S.; Robey, H. F.; Pak, A.; MacPhee, A. G.; Baker, K. L.; Weber, C. R.; Ma, T.; Park, H. -S.; Döppner, T.; Callahan, D. A.; Haan, S. W.; Patel, P. K.; Peterson, J. L.; Hoover, D.; Nikroo, A.; Yeamans, C. B.; Merrill, F. E.; Volegov, P. L.; Fittinghoff, D. N.; Grim, G. P.; Edwards, M. J.; Landen, O. L.; Lafortune, K. N.; MacGowan, B. J.; Widmayer, C. C.; Sayre, D. B.; Hatarik, R.; Bond, E. J.; Nagel, S. R.; Benedetti, L. R.; Izumi, N.; Khan, S.; Bachmann, B.; Spears, B. K.; Cerjan, C. J.; Gatu Johnson, M.; Frenje, J. A.

    2015-09-01

    Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR > 1 g=cm2. This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.

  15. Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive

    DOE PAGESBeta

    Casey, D. T.; Milovich, J. L.; Smalyuk, V. A.; Clark, D. S.; Robey, H. F.; Pak, A.; MacPhee, A. G.; Baker, K. L.; Weber, C. R.; Ma, T.; et al

    2015-09-01

    Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR > 1 g=cm2. This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.

  16. Measurement of High-Pressure Shock Waves in Cryogenic Deuterium-Tritium Ice Layered Capsule Implosions on NIF

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. PMID:23971581

  18. Comparison and analysis of 2-D simulation results with two implosion radiation experiments on the Los Alamos Pegasus I and Pegasus II capacitor banks

    SciTech Connect

    Peterson, D.L.; Bowers, R.L.; Lebeda, C.F.; Matuska, W.; Benage, J.; Idzorek, G.; Oona, H.; Stokes, J.; Roderick, N.F.

    1995-09-01

    Two experiments, PegI-41, conducted on the Los Alamos Pegasus I capacitor bank, and PegII-25, on the Pegasus II bank, consisted of the implosions of 13 mg (nominal), 5 cm radius, 2 cm high thin cylindrical aluminum foils resulting in soft x-ray radiation pulses from the plasma thermalization on axis. The implosions were conducted in direct-drive (no intermediate switching) mode with peak currents of about 4 MA and 5 MA respectively, and implosion times of about 2.5 {micro}s and 2.0 {micro}s. A radiation yield of about 250 kJ was measured for PegII-25. The purpose of these experiments was to examine the physics of the implosion and relate this physics to the production of the radiation pulse and to provide detailed experimental data which could be compared with 2-D radiation-magnetohydrodynamic (RMHD) simulations. Included in the experimental diagnostic suites were faraday rotation and dB/dt current measurements, a visible framing camera, an x-ray stripline camera, time-dependent spectroscopy, bolometers and XRD`S. A comparison of the results from these experiments shows agreement with 2-D simulation results in the instability development, current, and radiation pulse data, including the pulsewidth, shape, peak power and total radiation yield as measured by bolometry. Instabilities dominate the behavior of the implosion and largely determine the properties of the resulting radiation pulse. The 2-D simulations can be seen to be an important tool in understanding the implosion physics.

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

    PubMed

    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. PMID:24522535

  20. Characterization of the Determinants of NS2-3-Independent Virion Morphogenesis of Pestiviruses

    PubMed Central

    Klemens, O.; Dubrau, D.

    2015-01-01

    diarrhea virus, nonstructural protein NS2-3 is of critical importance to switch between these processes. While free NS3 is essential for RNA replication, uncleaved NS2-3, which accumulates over time in the infected cell, is required for virion morphogenesis. In contrast, the virion morphogenesis of the related hepatitis C virus is independent from uncleaved NS2-NS3. Here, we demonstrate that pestiviruses can adapt to virion morphogenesis in the absence of uncleaved NS2-3 by just two amino acid exchanges. While the mechanism behind this gain of function remains elusive, the fact that it can be achieved by such minor changes is in line with the assumption that an ancestral virus already used this mechanism but lost it in the course of adapting to a new host/infection strategy. PMID:26355097

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

    SciTech Connect

    Gu, Jianfa Dai, Zhensheng; Zou, Shiyang; Song, Peng; Ye, Wenhua; Zheng, Wudi; Gu, Peijun

    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.

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

    NASA Astrophysics Data System (ADS)

    Gu, Jianfa; Dai, Zhensheng; Zou, Shiyang; Song, Peng; Ye, Wenhua; Zheng, Wudi; Gu, Peijun

    2015-12-01

    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.

  3. Allosteric inhibition of the NS2B-NS3 protease from dengue virus.

    PubMed

    Yildiz, Muslum; Ghosh, Sumana; Bell, Jeffrey A; Sherman, Woody; Hardy, Jeanne A

    2013-12-20

    Dengue virus is the flavivirus that causes dengue fever, dengue hemorrhagic disease, and dengue shock syndrome, which are currently increasing in incidence worldwide. Dengue virus protease (NS2B-NS3pro) is essential for dengue virus infection and is thus a target of therapeutic interest. To date, attention has focused on developing active-site inhibitors of NS2B-NS3pro. The flat and charged nature of the NS2B-NS3pro active site may contribute to difficulties in developing inhibitors and suggests that a strategy of identifying allosteric sites may be useful. We report an approach that allowed us to scan the NS2B-NS3pro surface by cysteine mutagenesis and use cysteine reactive probes to identify regions of the protein that are susceptible to allosteric inhibition. This method identified a new allosteric site utilizing a circumscribed panel of just eight cysteine variants and only five cysteine reactive probes. The allosterically sensitive site is centered at Ala125, between the 120s loop and the 150s loop. The crystal structures of WT and modified NS2B-NS3pro demonstrate that the 120s loop is flexible. Our work suggests that binding at this site prevents a conformational rearrangement of the NS2B region of the protein, which is required for activation. Preventing this movement locks the protein into the open, inactive conformation, suggesting that this site may be useful in the future development of therapeutic allosteric inhibitors. PMID:24164286

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

    SciTech Connect

    Borgman, T.D.

    1997-12-01

    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&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.

  5. Direct-Drive, Cryogenic Target Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.

    2004-11-01

    Direct-drive spherical implosions of cryogenic, D_2-filled capsules are being performed on the 60-beam OMEGA laser system. The targets are energy scaled from the baseline ignition design developed for the National Ignition Facility. Thin-walled (3- to 4-μm) CD polymer shells, ˜860 μm in diameter, are permeation-filled with ˜1000 atm of D2 gas. Once cooled to the D2 triple point ( ˜18.7 K), cryogenic layers are formed, characterized, and maintained to a uniformity of ˜2 μm rms. Low-adiabat ( ˜4), pulse shapes are used to study the effects on target performance of acceleration-phase Rayleigh--Taylor (RT) growth due to single-beam, short-wavelength nonuniformities (imprint) and deceleration-phase RT growth of the combined feedthrough and inner-surface perturbations. Full single-beam smoothing (1-THz bandwidth, 2-D SSD with polarization smoothing) is used on all of the drive pulses. Time-resolved and static x-ray images are used to measure the progress of the imploding shell and the shape of the stagnating core. Particle-based instruments are used to measure the fusion yield and rate, the ion temperature in the core, and the total fuel areal density. These experiments have produced fuel areal densities up to ˜100 mg/cm^2, primary neutron yields of ˜10^11, and secondary neutron yields ˜1% to 2% of the primary yield. Two-dimensional hydrocode simulations show good agreement with the experimental observations, and the scaled target performance is compared with the hydrocode predictions for the direct-drive ignition point design. Such comparisons give increasing confidence in the direct-drive approach to ICF ignition.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Schmitt, Mark J.; Bradley, Paul A.; Cobble, James A.; Fincke, James R.; Hakel, Peter; Hsu, Scott C.; Krasheninnikova, Natalia S.; Kyrala, George A.; Magelssen, Glenn R.; Montgomery, David S.; Murphy, Thomas J.; Obrey, Kimberly A.; Shah, Rahul C.; Tregillis, Ian L.; Baumgaertel, Jessica A.; Wysocki, Frederick J.; Batha, Steven H.; Stephen Craxton, R.; McKenty, Patrick W.; Fitzsimmons, Paul; Nikroo, Abbas; Wallace, Russell

    2013-05-01

    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.

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

    SciTech Connect

    Kyrala, G. A.; Kline, J. L.; 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.; Kilkenny, J.

    2010-10-15

    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 {mu}m 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.

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

    PubMed

    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. PMID:21034014

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

    SciTech Connect

    Schmitt, Mark J.; Bradley, Paul A.; Cobble, James A.; Fincke, James R.; Hakel, Peter; Hsu, Scott C.; Krasheninnikova, Natalia S.; Kyrala, George A.; Magelssen, Glenn R.; Montgomery, David S.; Murphy, Thomas J.; Obrey, Kimberly A.; Shah, Rahul C.; Tregillis, Ian L.; Baumgaertel, Jessica A.; Wysocki, Frederick J.; Batha, Steven H.; Stephen Craxton, R.; McKenty, Patrick W.; Fitzsimmons, Paul; and others

    2013-05-15

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2012-10-01

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

    PubMed

    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

    2012-10-01

    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-α 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. PMID:23126948

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

    PubMed

    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

    2016-08-12

    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. PMID:27563971

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Bluetongue Virus Nonstructural Protein NS3/NS3a Is Not Essential for Virus Replication

    PubMed Central

    van Gennip, René G. P.; van de Water, Sandra G. P.; van Rijn, Piet A.

    2014-01-01

    Orbiviruses form the largest genus of the family Reoviridae consisting of at least 23 different virus species. One of these is the bluetongue virus (BTV) and causes severe hemorrhagic disease in ruminants, and is transmitted by bites of Culicoides midges. BTV is a non-enveloped virus which is released from infected cells by cell lysis and/or a unique budding process induced by nonstructural protein NS3/NS3a encoded by genome segment 10 (Seg-10). Presence of both NS3 and NS3a is highly conserved in Culicoides borne orbiviruses which is suggesting an essential role in virus replication. We used reverse genetics to generate BTV mutants to study the function of NS3/NS3a in virus replication. Initially, BTV with small insertions in Seg-10 showed no CPE but after several passages these BTV mutants reverted to CPE phenotype comparable to wtBTV, and NS3/NS3a expression returned by repair of the ORF. These results show that there is a strong selection for functional NS3/NS3a. To abolish NS3 and/or NS3a expression, Seg-10 with one or two mutated start codons (mutAUG1, mutAUG2 and mutAUG1+2) were used to generate BTV mutants. Surprisingly, all three BTV mutants were generated and the respective AUGMet→GCCAla mutations were maintained. The lack of expression of NS3, NS3a, or both proteins was confirmed by westernblot analysis and immunostaining of infected cells with NS3/NS3a Mabs. Growth of mutAUG1 and mutAUG1+2 virus in BSR cells was retarded in both insect and mammalian cells, and particularly virus release from insect cells was strongly reduced. Our findings now enable research on the role of RNA sequences of Seg-10 independent of known gene products, and on the function of NS3/NS3a proteins in both types of cells as well as in the host and insect vector. PMID:24465709

  16. Self-generated magnetic fields in direct-drive implosion experiments

    NASA Astrophysics Data System (ADS)

    Igumenshchev, I. V.; Zylstra, A. B.; Li, C. K.; Nilson, P. M.; Goncharov, V. N.; Petrasso, R. D.

    2014-06-01

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ˜10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ˜1015 W/cm2. Proton radiographs show multiple ring-like structures produced by electric fields ˜107 V/cm and fine structures from surface defects, indicating self-generated fields up to ˜3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇Te × ∇ne source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

  17. First high-convergence cryogenic implosion in a near-vacuum hohlraum

    DOE PAGESBeta

    Berzak Hopkins, L.  F.; Meezan, N.  B.; Le Pape, S.; Divol, L.; Mackinnon, A.  J.; Ho, D.  D.; Hohenberger, M.; Jones, O.  S.; Kyrala, G.; Milovich, J.  L.; et al

    2015-04-29

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated inmore » a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ~ 3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 X 10¹⁵ neutrons, with 20% calculated alpha heating at convergence ~27X.« less

  18. First High-Convergence Cryogenic Implosion in a Near-Vacuum Hohlraum

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L. F.; Meezan, N. B.; Le Pape, S.; Divol, L.; Mackinnon, A. J.; Ho, D. D.; Hohenberger, M.; Jones, O. S.; Kyrala, G.; Milovich, J. L.; Pak, A.; Ralph, J. E.; Ross, J. S.; Benedetti, L. R.; Biener, J.; Bionta, R.; Bond, E.; Bradley, D.; Caggiano, J.; Callahan, D.; Cerjan, C.; Church, J.; Clark, D.; Döppner, T.; Dylla-Spears, R.; Eckart, M.; Edgell, D.; Field, J.; Fittinghoff, D. N.; Gatu Johnson, M.; Grim, G.; Guler, N.; Haan, S.; Hamza, A.; Hartouni, E. P.; Hatarik, R.; Herrmann, H. W.; Hinkel, D.; Hoover, D.; Huang, H.; Izumi, N.; Khan, S.; Kozioziemski, B.; Kroll, J.; Ma, T.; MacPhee, A.; McNaney, J.; Merrill, F.; Moody, J.; Nikroo, A.; Patel, P.; Robey, H. F.; Rygg, J. R.; Sater, J.; Sayre, D.; Schneider, M.; Sepke, S.; Stadermann, M.; Stoeffl, W.; Thomas, C.; Town, R. P. J.; Volegov, P. L.; Wild, C.; Wilde, C.; Woerner, E.; Yeamans, C.; Yoxall, B.; Kilkenny, J.; Landen, O. L.; Hsing, W.; Edwards, M. J.

    2015-05-01

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ˜3.5 ) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 ×1015 neutrons, with 20% calculated alpha heating at convergence ˜27 × .

  19. First high-convergence cryogenic implosion in a near-vacuum hohlraum.

    PubMed

    Berzak Hopkins, L F; Meezan, N B; Le Pape, S; Divol, L; Mackinnon, A J; Ho, D D; Hohenberger, M; Jones, O S; Kyrala, G; Milovich, J L; Pak, A; Ralph, J E; Ross, J S; Benedetti, L R; Biener, J; Bionta, R; Bond, E; Bradley, D; Caggiano, J; Callahan, D; Cerjan, C; Church, J; Clark, D; Döppner, T; Dylla-Spears, R; Eckart, M; Edgell, D; Field, J; Fittinghoff, D N; Gatu Johnson, M; Grim, G; Guler, N; Haan, S; Hamza, A; Hartouni, E P; Hatarik, R; Herrmann, H W; Hinkel, D; Hoover, D; Huang, H; Izumi, N; Khan, S; Kozioziemski, B; Kroll, J; Ma, T; MacPhee, A; McNaney, J; Merrill, F; Moody, J; Nikroo, A; Patel, P; Robey, H F; Rygg, J R; Sater, J; Sayre, D; Schneider, M; Sepke, S; Stadermann, M; Stoeffl, W; Thomas, C; Town, R P J; Volegov, P L; Wild, C; Wilde, C; Woerner, E; Yeamans, C; Yoxall, B; Kilkenny, J; Landen, O L; Hsing, W; Edwards, M J

    2015-05-01

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α∼3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8×10(15) neutrons, with 20% calculated alpha heating at convergence ∼27×. PMID:25978240

  20. Self-generated magnetic fields in direct-drive implosion experiments

    SciTech Connect

    Igumenshchev, I. V.; Nilson, P. M.; Goncharov, V. N.; Zylstra, A. B.; Li, C. K.; Petrasso, R. D.

    2014-06-15

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ∼10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ∼10{sup 15} W/cm{sup 2}. Proton radiographs show multiple ring-like structures produced by electric fields ∼10{sup 7} V/cm and fine structures from surface defects, indicating self-generated fields up to ∼3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇T{sub e} × ∇n{sub e} source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

  1. Self-generated magnetic fields in direct-drive implosion experiments

    SciTech Connect

    Igumenshchev, I. V.; Zylstra, A. B.; Li, C. K.; Nilson, P. M.; Goncharov, V. N.; Petrasso, R. D.

    2014-06-13

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ~10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ~1015 W/cm2. Proton radiographs show multiple ring-like structures produced by electric fields ~107 V/cm and fine structures from surface defects, indicating self-generated fields up to ~3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇Te × ∇ne source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

  2. First high-convergence cryogenic implosion in a near-vacuum hohlraum

    SciTech Connect

    Berzak Hopkins, L.  F.; Meezan, N.  B.; Le Pape, S.; Divol, L.; Mackinnon, A.  J.; Ho, D.  D.; Hohenberger, M.; Jones, O.  S.; Kyrala, G.; Milovich, J.  L.; Pak, A.; Ralph, J.  E.; Ross, J.  S.; Benedetti, L.  R.; Biener, J.; Bionta, R.; Bond, E.; Bradley, D.; Caggiano, J.; Callahan, D.; Cerjan, C.; Church, J.; Clark, D.; Döppner, T.; Dylla-Spears, R.; Eckart, M.; Edgell, D.; Field, J.; Fittinghoff, D.  N.; Gatu Johnson, M.; Grim, G.; Guler, N.; Haan, S.; Hamza, A.; Hartouni, E.  P.; Hatarik, R.; Herrmann, H.  W.; Hinkel, D.; Hoover, D.; Huang, H.; Izumi, N.; Khan, S.; Kozioziemski, B.; Kroll, J.; Ma, T.; MacPhee, A.; McNaney, J.; Merrill, F.; Moody, J.; Nikroo, A.; Patel, P.; Robey, H.  F.; Rygg, J.  R.; Sater, J.; Sayre, D.; Schneider, M.; Sepke, S.; Stadermann, M.; Stoeffl, W.; Thomas, C.; Town, R.  P. J.; Volegov, P.  L.; Wild, C.; Wilde, C.; Woerner, E.; Yeamans, C.; Yoxall, B.; Kilkenny, J.; Landen, O.  L.; Hsing, W.; Edwards, M.  J.

    2015-04-29

    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ~ 3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 X 10¹⁵ neutrons, with 20% calculated alpha heating at convergence ~27X.

  3. Spin Complicates Eccentric BH-NS Mergers

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    When a neutron star (NS) has a glancing encounter with a black hole (BH), its spin has a significant effect on the outcome, according to new simulations run by William East of Stanford University and his collaborators. Spotting an Eccentric Merger. In a traditional BH-NS merger, the two objects orbit each other quasi-circularly as they spiral in. But there's another kind of merger that's possible in high-density environments like galactic nuclei or globular clusters: a dynamical capture merger, in which a NS and BH pass each other just close enough that the gravity of the black hole "catches" the NS, leading the two objects to merge with very eccentric orbits. During an eccentric merger, the NS can be torn apart -- at which point some fraction of the tidally-disrupted material will escape the system, while some fraction instead accretes back onto the BH. Knowing these fractions is important for being able to model the expected electromagnetic signatures for the merger: the unbound material can power transients like kilonovae, whereas the accreting material may be the cause of short gamma-ray bursts. The amount of material available for events like these would change their observable strengths. Testing the Effects of Spin. To see whether NS spin has an impact on the behavior of the merger, East and collaborators use a general-relativistic hydrodynamic code to simulate the glancing encounter of a BH and a NS with dimensionless spin between a=0 (non-spinning) and a=0.756 (rotation period of 1 ms). They also vary the separation of the first encounter. The group finds that changing the NS's spin can change a number of outcomes of the merger. To start with, it can affect whether the NS is captured by the BH, or if the encounter is glancing and then both objects carry on their merry way. And if the NS is trapped by the BH and torn apart, then the higher the NS's spin, the more matter outside of the BH ends up unbound, instead of getting trapped into an accretion disk

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

    NASA Astrophysics Data System (ADS)

    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%.

  5. Diagnosing Cross-Beam Energy Transfer Using Beamlets of Unabsorbed Light from Direct-Drive Implosions

    NASA Astrophysics Data System (ADS)

    Edgell, D. H.; Follett, R. K.; Goncharov, V. N.; Igumenshchev, I. V.; Katz, J.; Myatt, J. F.; Seka, W.; Froula, D. H.

    2015-11-01

    A new diagnostic is now being fielded to record the unabsorbed laser light from implosions on OMEGA. Unabsorbed light from each OMEGA beam is imaged as a distinct ``spot'' in time-integrated images. Each spot is, in essence, the end point of a beamlet of light that originates from a specific region of a beam profile and follows a path determined by refraction. The intensity of light in the beamlet varies along that path because of absorption and cross-beam energy transfer (CBET) with other beamlets. This diagnostic allows for the detailed investigation of the effects of CBET on specific locations of the beam profile. A pinhole can be used to isolate specific spots, allowing the time-resolved spectrum of the beamlet to be measured. A fully 3-D CBET hydrodynamics code postprocessor is used to model the intensity and wavelength of each beamlet as it traverses the coronal plasma to the diagnostic. The model predicts that if a single beam in a symmetric implosion is turned off, the recorded intensity of nearby spots will decrease by ~ 15% as a result of loss of CBET from the dropped beam. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

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

    SciTech Connect

    Vold, E. L.; Molvig, K.; Joglekar, A. S.; Ortega, M. I.; Moll, R.; Fenn, D.

    2015-11-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Vold, E. L.; Joglekar, A. S.; Ortega, M. I.; Moll, R.; Fenn, D.; Molvig, K.

    2015-11-01

    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 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.

  8. Implosion characteristics and applications of combined tungsten-aluminum Z-pinch planar arrays

    NASA Astrophysics Data System (ADS)

    Osborne, G. C.; Kantsyrev, V. L.; Esaulov, A. A.; Safronova, A. S.; Weller, M. E.; Shrestha, I.; Williamson, K. M.; Shlyaptseva, V. V.

    2013-12-01

    An exploration of the implosion properties and X-ray radiation pulses from tungsten-based planar wire array Z-pinch experiments is presented, with an emphasis on loads mixed with aluminum. These experiments were carried out on Zebra, the 1.0 MA pulse power generator at the Nevada Terawatt Facility. A suite of diagnostics was used to study these plasmas, including X-ray and EUV Si diodes, optical imaging, laser shadowgraphy, and time-gated and time-integrated X-ray pinhole imagers and spectrometers. Specifically, loads with relatively large inter-wire gaps where tungsten is placed in the center of a planar configuration composed primarily of aluminum showed unusual characteristics. These loads are shown to generate a "bubbling" effect in which plasma from the ablation of outer aluminum wires is temporarily hindered from converging at the center of the array where the tungsten wire is located. Reproduction of these experiments with variations to load geometry, materials, and mass distribution are also presented and discussed in an attempt to better understand the phenomenon. In addition, a theoretical model has also been applied to better understand the dynamics of the implosions of these loads. Applications of this effect to radiation pulse shaping, particularly with multi-planar arrays, are also discussed.

  9. Rationalizing meat consumption. The 4Ns.

    PubMed

    Piazza, Jared; Ruby, Matthew B; Loughnan, Steve; Luong, Mischel; Kulik, Juliana; Watkins, Hanne M; Seigerman, Mirra

    2015-08-01

    Recent theorizing suggests that the 4Ns - that is, the belief that eating meat is natural, normal, necessary, and nice - are common rationalizations people use to defend their choice of eating meat. However, such theorizing has yet to be subjected to empirical testing. Six studies were conducted on the 4Ns. Studies 1a and 1b demonstrated that the 4N classification captures the vast majority (83%-91%) of justifications people naturally offer in defense of eating meat. In Study 2, individuals who endorsed the 4Ns tended also to objectify (dementalize) animals and included fewer animals in their circle of moral concern, and this was true independent of social dominance orientation. Subsequent studies (Studies 3-5) showed that individuals who endorsed the 4Ns tend not to be motivated by ethical concerns when making food choices, are less involved in animal-welfare advocacy, less driven to restrict animal products from their diet, less proud of their animal-product decisions, tend to endorse Speciesist attitudes, tend to consume meat and animal products more frequently, and are highly committed to eating meat. Furthermore, omnivores who strongly endorsed the 4Ns tended to experience less guilt about their animal-product decisions, highlighting the guilt-alleviating function of the 4Ns. PMID:25865663

  10. X-ray driven implosions at ignition relevant velocities on the National Ignition Facility

    SciTech Connect

    Meezan, N. B.; MacKinnon, A. J.; Hicks, D. G.; Dewald, E. L.; Tommasini, R.; Le Pape, S.; Döppner, T.; Ma, T.; Farley, D. R.; Kalantar, D. H.; Di Nicola, P.; Callahan, D. A.; Robey, H. F.; Thomas, C. A.; Prisbrey, S. T.; Jones, O. S.; Milovich, J. L.; Clark, D. S.; Eder, D. C.; Schneider, M. B.; and others

    2013-05-15

    Backlit convergent ablator experiments on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] are indirect drive implosions that study the inflight dynamics of an imploding capsule. Side-on, backlit radiography provides data used by the National Ignition Campaign to measure time-dependent properties of the capsule ablator including its center of mass radius, velocity, and unablated mass. Previously, Callahan [D. A. Callahan et al., Phys. Plasmas 19, 056305 (2012)] and Hicks [D. H. Hicks et al., Phys. Plasmas 19, 122702 (2012)] reported backlit convergent ablator experiments demonstrating velocities approaching those required for ignition. This paper focuses on implosion performance data in the “rocket curve” plane, velocity vs. ablator mass. These rocket curve data, along with supporting numerical simulations, show that the nominal 195 μm-thick ignition capsule would reach the ignition velocity goal V = 370 km/s with low ablator mass remaining–below the goal of M = 0.25 mg. This finding led to experiments with thicker capsule ablators. A recent symmetry capsule experiment with a 20 μm thicker capsule driven by 520 TW, 1.86 MJ laser pulse (along with a companion backlit convergent ablator experiment) appears to have demonstrated V≥350 km/s with ablator mass remaining above the ignition goal.

  11. X-ray driven implosions at ignition relevant velocities on the National Ignition Facilitya)

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.; MacKinnon, A. J.; Hicks, D. G.; Dewald, E. L.; Tommasini, R.; Le Pape, S.; Döppner, T.; Ma, T.; Farley, D. R.; Kalantar, D. H.; Di Nicola, P.; Callahan, D. A.; Robey, H. F.; Thomas, C. A.; Prisbrey, S. T.; Jones, O. S.; Milovich, J. L.; Clark, D. S.; Eder, D. C.; Schneider, M. B.; Widmann, K.; Koch, J. A.; Salmonson, J. D.; Opachich, Y. P.; Benedetti, L. R.; Khan, S. F.; MacPhee, A. G.; Glenn, S. M.; Bradley, D. K.; Dzenitis, E. G.; Nathan, B. R.; Kroll, J. J.; Hamza, A. V.; Dixit, S. N.; Atherton, L. J.; Landen, O. L.; Glenzer, S. H.; Hsing, W. W.; Suter, L. J.; Edwards, M. J.; MacGowan, B. J.; Moses, E. I.; Olson, R. E.; Kline, J. L.; Kyrala, G. A.; Moore, A. S.; Kilkenny, J. D.; Nikroo, A.; Moreno, K.; Hoover, D. E.

    2013-05-01

    Backlit convergent ablator experiments on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] are indirect drive implosions that study the inflight dynamics of an imploding capsule. Side-on, backlit radiography provides data used by the National Ignition Campaign to measure time-dependent properties of the capsule ablator including its center of mass radius, velocity, and unablated mass. Previously, Callahan [D. A. Callahan et al., Phys. Plasmas 19, 056305 (2012)] and Hicks [D. H. Hicks et al., Phys. Plasmas 19, 122702 (2012)] reported backlit convergent ablator experiments demonstrating velocities approaching those required for ignition. This paper focuses on implosion performance data in the "rocket curve" plane, velocity vs. ablator mass. These rocket curve data, along with supporting numerical simulations, show that the nominal 195 μm-thick ignition capsule would reach the ignition velocity goal V = 370 km/s with low ablator mass remaining-below the goal of M = 0.25 mg. This finding led to experiments with thicker capsule ablators. A recent symmetry capsule experiment with a 20 μm thicker capsule driven by 520 TW, 1.86 MJ laser pulse (along with a companion backlit convergent ablator experiment) appears to have demonstrated V ≥350 km/s with ablator mass remaining above the ignition goal.

  12. Evaluation of laser light specularly reflected by the hohlraum surface on OMEGA indirect implosion experiments

    NASA Astrophysics Data System (ADS)

    Izumi, Nobuhiko; Turner, R. E.; Landen, O. L.; Wallace, R. J.; Koch, R. A.

    2003-10-01

    Due to the cylindrical shape of hohlraums typically used in indirect implosion experiments, the laser beams specularly reflected by the inner hohlraum surface are focused onto the capsule surface. This effect, which is known as the glint light effect, is important during the early stages of laser irradiation ( ˜200 ps), and might seed undesirable hydrodynamic instabilities which could grow during the implosion. We performed ray-trace calculations to evaluate this effect, and found that with a typical laser configuration the peak intensity of glint light can be up to 4 × 10^14 W/cm^2. We also performed experiments to measure of glint light effect at Omega using a time resolved x-ray re-emission technique, and evaluated the effect of rough hohlraum walls on the glint light intensity and spatial distribution. The results of the calculations and experiments will be presented. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. A Kirkpatrick-Baez Microscope for Core Implosion Imaging at NIF

    NASA Astrophysics Data System (ADS)

    Pickworth, Louisa; Bradley, David; Pardini, Tommaso; Smalyuk, Vladimir; Izumi, Nobuhiko; Pivovaroff, Michael; Vogel, Julia; Walton, Christopher; Mirkarimi, Paul; Bell, Perry; Decker, Todd; McCarville, Thomas; Ayers, Marion; Kilkenny, Joseph

    2013-10-01

    ICF experiments have typical core diameters raging from 50 μ m, in layered implosions, to 100 μ m in SymCaps. The emission spectrum is peaked between 8 and 10 keV. Current X-ray imaging at NIF uses time resolved pinhole cameras with 10-20 μ m pinholes that limit resolution and throughput to the detector. Selection of observed photon energy requires filtering that further reduces transmission. Low resolution, in combination with poor signal to noise ratio, limits the observable features during the later stages of capsule implosion. Using grazing incidence mirrors in a Kirkpatrick-Baez (KB) configuration, a focusing x-ray microscope is in design for NIF. The system will have x12 magnification, detector limited resolution and x10 higher throughput in comparison to pinhole systems. A KB microscope for imaging ICF experiments will be described, utilizing multilayer mirrors to enhance reflectivity for the core emission. Optimization of the multilayer coating allows observation of extended sources and high reflectivity in a selected energy band > 0 . 2 keV. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-640864.

  15. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    SciTech Connect

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  16. Comparison of measured soft x-ray drive with shock and capsule implosion velocity for ignition tuning experiments on NIF

    NASA Astrophysics Data System (ADS)

    Kline, J.; Callahan, D.; Meezan, N.; Glenzer, S.; MacKinnon, A.; Dixit, S.; Kyrala, G.; Widmann, K.; Robey, H.; Clark, D.; Jones, O.; Hicks, D.; Celliers, P.; Farley, D.; Town, R.; Kalantar, D.; Dewald, E.; Moore, A.; Olson, R.; Doeppner, T.; Moody, J.; Ralph, J.; Thomas, C.; Landen, O.; Edwards, M.

    2011-10-01

    Indirect drive inertial confinement fusion experiments use high-Z hohlraums to convert laser energy to soft x-ray energy. The soft x-rays then drive the capsule via material ablation to compress the fuel payload and heat the central hot spot to initiate ignition. To achieve the highest fuel compression, a shaped radiation drive is used launching multiple shocks timed minimizes fuel entropy. The strength and velocity of these shocks depend directly on the radiation drive. The main laser pulse is then used to drive the implosion such that the PdV work can heat the central core to fusion conditions. To diagnose the soft x-ray drive in the hohlraum, Dante, an 18 channel soft x-ray spectrometer, measures the flux escaping the laser entrance hole. Measurements of this flux are used to assess the conditions for the capsule implosion. In this presentation, we will examine correlations between the soft x-ray measurements and shock velocity, as well as implosion velocity for recent ignition tuning experiments on NIF.

  17. Sensitivity of capsule implosion symmetry due to laser beam imbalance in a scale 0.2 hot hohlraum at Omega

    NASA Astrophysics Data System (ADS)

    Delamater, N. D.; Wilson, D. C.; Kyrala, G. A.; Seifter, A.; Hoffman, N. M.

    2010-08-01

    Results are shown from recent experiments at the Omega laser facility, using 40 Omega beams driving the hohlraum with 3 cones from each side and up to 19.5 kJ of laser energy. Beam phasing is achieved by decreasing the energy separately in each of the three cones, by 3 kJ, for a total drive energy of 16.5 kJ. This results in a more asymmetric drive, which will vary the shape of the imploded symmetry capsule core from round to oblate or prolate in a systematic and controlled manner. These results show the sensitivity of capsule implosion symmetry for implosions in "high temperature" (275 eV) hohlraums at Omega. Dante measurements confirmed the predicted peak drive temperatures of 275 eV. Implosion core time dependent x-ray images were obtained from framing camera data which show the expected change in symmetry due to beam imbalance and which also agree well with post processed hydro code calculations.

  18. Sensitivity study of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum

    SciTech Connect

    Gu Jianfa; Zou Shiyang; Li Yongsheng; Dai Zhensheng; Ye Wenhua

    2012-12-15

    The paper investigates theoretically the sensitivities of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum. In the simulation, the hohlraum radiation is represented by a Planckian spectrum for the main drive plus a gaussian bump centered at energy E{sub c} for preheating x-rays. Simulation results show that with the increasing of center energy E{sub c}, the Atwood number at the fuel-ablator interface increases rapidly due to the preheating and expanding of the inner undoped CH layer. The growing of Atwood number indicates the hydrodynamic instability (HI) growth and mixing at this interface. On the other hand, the increasing of E{sub c} results in a large density gradient scale length of ablation front and stabilizes the HI growth at ablation front. The changes of the hard x-ray spectrum have significant influences on other important implosion parameters including the ablator mass remaining, shock timing, implosion velocity, and yield as well. High-precision results on the hard x-ray spectral distribution of hohlraum are thus critical for optimizing the ignition capsule design to limit the HI growth.

  19. Instabilities in foil implosions and the effect of radiation output

    SciTech Connect

    Oona, H.; Peterson, D.L.; Goforth, J.H.

    1995-08-01

    One of the aims of the Athena program at the Los Alamos National Laboratory is the generation of a high fluence of soft x-rays from the thermalization of an radially imploding foil. In the experiments in Athena program, a large axial current is passed through a cylindrical aluminum foil. Under the action of the Lorentz force, the resulting plasma accelerates toward the axis, thermalizes, and produces a fast soft x-ray pulse with a blackbody temperature up to several hundred electron volts. In order that there be the maximum power compression and the highest x-ray fluence and temperature, the plasma stagnation on axis must occur very promptly. This requires that the imploding plasma be as thin and symmetric as possible. A serious problem in the thermalization process is the formation of instabilities in the plasma due to the self-magnetic field that governs the implosion of foil. A large diagnostic effort was developed to capture the details of the implosion and instability growth in several foil implosion experiments. In this report, we will present visible light images and x-ray data designed to study the effects of foil mass, current, and initial perturbations on the instability growth during foil implosion. Representative data is presented from several experiments using the Pegasus capacitor bank system and the explosively driven Procyon system. These experiments are labeled Peg 25 and Peg 33 for the Pegasus experiments and PDD1, PDD2 and PRF0 for the Procyon experiments. In these experiments, all foils had radii of 5 centimeters but varied in mass and initial conditions. Experimental data from several shots were compared with each other and to a radiation magnetohydrodynamic (RMHD) computation and described in a separate paper.

  20. Symmetry Tuning of Polar-Direct-Drive Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Hsu, S.; Cobble, J.; Murphy, T.; Krasheninnikova, N.; Baumgaertel, J.; Bradley, P.; Hakel, P.; Kanzleiter, R.; Schmitt, M.; Shah, R.; Tregillis, I.; Mancini, R.; Johns, H.; Joshi, T.; Mayes, D.; Nasewicz, S.

    2013-10-01

    Three laser cone energy balances and two laser pointings were used over two shot days on OMEGA to evaluate our control of symmetry for polar-direct-drive implosions, and to compare against the predictions of simulations. The spherical targets had 870- μm outer diameter, 17- μm thick CH shell, and 5-atm DD gas fill (nominal values). Various dopant combinations were used in both the shell (Ti and V) and gas (Ar). The primary diagnostic for evaluating implosion symmetry was backlit radiography imaged by an x-ray framing camera (day 1) and the LANL large format camera (day 2). For the secondary objective of evaluating shell-mix as a function of laser settings, we used a combination of x-ray spectral instruments including XRS, SSCA, and two MMI's. Neutron yields (from NTOF 5.4 m) were in the range ~ 0 . 5 - 3 ×1010 and the burn-averaged Ti was ~ 3 -4.5 keV. This talk focuses on experimental analysis/results on implosion symmetry as a function of variations in laser settings. Supported by DOE NNSA.

  1. Modeling of Low Feed-Through CD Mix Implosions

    NASA Astrophysics Data System (ADS)

    Pino, Jesse; MacLaren, Steven; Greenough, Jeff; Casey, Daniel; Dittrich, Tom; Kahn, Shahab; Kyrala, George; Ma, Tammy; Salmonson, Jay; Smalyuk, Vladimir; Tipton, Robert

    2015-11-01

    The CD Mix campaign previously demonstrated the use of nuclear diagnostics to study the mix of separated reactants in plastic capsule implosions at the National Ignition Facility. However, the previous implosions suffered from large instability growth seeded from perturbations on the outside of the capsule. Recently, the separated reactants technique has been applied to two platforms designed to minimize this feed-through and isolate local mix at the gas-ablator interface: the Two Shock (TS) and Adiabat-Shaped (AS) Platforms. Additionally, the background contamination of Deuterium in the gas has been greatly reduced, allowing for simultaneous observation of TT, DT, and DD neutrons, which respectively give information about core gas performance, gas-shell atomic mix, and heating of the shell. In this talk, we describe efforts to model these implosions using high-resolution 2D ARES simulations with both a Reynolds-Averaged Navier Stokes method and an enhanced diffusivity model. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-674867.

  2. Host cell killing by the West Nile Virus NS2B-NS3 proteolytic complex: NS3 alone is sufficient to recruit caspase-8-based apoptotic pathway

    SciTech Connect

    Ramanathan, Mathura P.; Chambers, Jerome A.; Pankhong, Panyupa; Chattergoon, Michael; Attatippaholkun, Watcharee; Dang, Kesen; Shah, Neelima; Weiner, David B. . E-mail: dbweiner@mail.med.upenn.edu

    2006-02-05

    The West Nile Virus (WNV) non-structural proteins 2B and 3 (NS2B-NS3) constitute the proteolytic complex that mediates the cleavage and processing of the viral polyprotein. NS3 recruits NS2B and NS5 proteins to direct protease and replication activities. In an effort to investigate the biology of the viral protease, we cloned cDNA encoding the NS2B-NS3 proteolytic complex from brain tissue of a WNV-infected dead crow, collected from the Lower Merion area (Merion strain). Expression of the NS2B-NS3 gene cassette induced apoptosis within 48 h of transfection. Electron microscopic analysis of NS2B-NS3-transfected cells revealed ultra-structural changes that are typical of apoptotic cells including membrane blebbing, nuclear disintegration and cytoplasmic vacuolations. The role of NS3 or NS2B in contributing to host cell apoptosis was examined. NS3 alone triggers the apoptotic pathways involving caspases-8 and -3. Experimental results from the use of caspase-specific inhibitors and caspase-8 siRNA demonstrated that the activation of caspase-8 was essential to initiate apoptotic signaling in NS3-expressing cells. Downstream of caspase-3 activation, we observed nuclear membrane ruptures and cleavage of the DNA-repair enzyme, PARP in NS3-expressing cells. Nuclear herniations due to NS3 expression were absent in the cells treated with a caspase-3 inhibitor. Expression of protease and helicase domains themselves was sufficient to trigger apoptosis generating insight into the apoptotic pathways triggered by NS3 from WNV.

  3. Phosphoproteomics Identified an NS5A Phosphorylation Site Involved in Hepatitis C Virus Replication.

    PubMed

    Chong, Weng Man; Hsu, Shih-Chin; Kao, Wei-Ting; Lo, Chieh-Wen; Lee, Kuan-Ying; Shao, Jheng-Syuan; Chen, Yi-Hung; Chang, Justin; Chen, Steve S-L; Yu, Ming-Jiun

    2016-02-19

    The non-structural protein 5A (NS5A) is a hepatitis C virus (HCV) protein indispensable for the viral life cycle. Many prior papers have pinpointed several serine residues in the low complexity sequence I region of NS5A responsible for NS5A phosphorylation; however, the functions of specific phosphorylation sites remained obscure. Using phosphoproteomics, we identified three phosphorylation sites (serines 222, 235, and 238) in the NS5A low complexity sequence I region. Reporter virus and replicon assays using phosphorylation-ablated alanine mutants of these sites showed that Ser-235 dominated over Ser-222 and Ser-238 in HCV replication. Immunoblotting using an Ser-235 phosphorylation-specific antibody showed a time-dependent increase in Ser-235 phosphorylation that correlated with the viral replication activity. Ser-235 phosphorylated NS5A co-localized with double-stranded RNA, consistent with its role in HCV replication. Mechanistically, Ser-235 phosphorylation probably promotes the replication complex formation via increasing NS5A interaction with the human homologue of the 33-kDa vesicle-associated membrane protein-associated protein. Casein kinase Iα (CKIα) directly phosphorylated Ser-235 in vitro. Inhibition of CKIα reduced Ser-235 phosphorylation and the HCV RNA levels in the infected cells. We concluded that NS5A Ser-235 phosphorylated by CKIα probably promotes HCV replication via increasing NS5A interaction with the 33-kDa vesicle-associated membrane protein-associated protein. PMID:26702051

  4. Time-Resolved Absorption in Cryogenic and Room-Temperature, Direct-Drive Imploding Targets

    NASA Astrophysics Data System (ADS)

    Seka, W.

    2007-11-01

    Time-resolved absorption has been measured in direct-drive-implosion experiments for various targets and pulse shapes using OMEGA's UV Laser System. These experiments reveal a number of interaction processes beyond inverse bremsstrahlung absorption. During the first 100 to 200 ps, evidence of enhanced absorption points toward resonance absorption. Depending on target material and pulse shapes, the absorption at times t > 0.7 ns is reduced compared to predictions by hydrodynamic simulations with flux-limited electron heat transport. This discrepancy may be partly due to uncertainties in the heat transport model. Scattered light spectra further indicate that beam-to-beam energy transfer with gain provided by stimulated Brillouin scattering (SBS) may also contribute. Evidence for two-plasmon-decay (TPD) instability is seen in almost all direct-drive-implosion experiments as evidenced by hard-x-ray and 3φ/2 emission. The TPD instability is driven particularly hard when the laser burns through the CD shell during the laser pulse in a cryogenic target implosion with the concomitant possibility of fast-electron preheat. This wealth of interaction processes will be discussed along with implications for future larger-scale experiments. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement DE-FC52-92SF19460. Contributors: D.H. Edgell, V.N. Goncharov, I.V. Igumenshchev, J.A. Delettrez, J. Myatt, A.V. Maximov, R.W. Short, C. Stoeckl, and T.C. Sangster.

  5. Progress on New Hepatitis C Virus Targets: NS2 and NS5A

    NASA Astrophysics Data System (ADS)

    Marcotrigiano, Joseph

    Hepatitis C virus (HCV) is a major global health problem, affecting about 170 million people worldwide. Chronic infection can lead to cirrhosis and liver cancer. The replication machine of HCV is a multi-subunit membrane associated complex, consisting of nonstructural proteins (NS2-5B), which replicate the viral RNA genome. The structures of NS5A and NS2 were recently determined. NS5A is an essential replicase component that also modulates numerous cellular processes ranging from innate immunity to cell growth and survival. The structure reveals a novel protein fold, a new zinc coordination motif, a disulfide bond and a dimer interface. Analysis of molecular surfaces suggests the location of the membrane interaction surface of NS5A, as well as hypothetical protein and RNA binding sites. NS2 is one of two virally encoded proteases that are required for processing the viral polyprotein into the mature nonstructural proteins. NS2 is a dimeric cysteine protease with two composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer and the nucleophilic cysteine by the other. The C-terminal residues remain coordinated in the two active sites, predicting an inactive post-cleavage form. The structure also reveals possible sites of membrane interaction, a rare cis-proline residue, and highly conserved dimer contacts. The novel features of both structures have changed the current view of HCV polyprotein replication and present new opportunities for antiviral drug design.

  6. Raman spectroscopy based discrimination of NS1 positive and negative dengue virus infected serum

    NASA Astrophysics Data System (ADS)

    Bilal, M.; Saleem, M.; Bilal, Maria; Khurram, M.; Khan, Saranjam; Ullah, Rahat; Ali, Hina; Ahmed, M.

    2016-09-01

    This study is intended to develop a multivariate statistical model for the prediction of nonstructural protein 1 (NS1) in dengue virus (DENV) infected blood serum in humans. The model has been developed on the basis of partial least squares regression using the Raman spectra of NS1 positive and NS1 negative samples. Human blood sera of 218 subjects is included in this study, of which 95 were NS1 positive and 123 were NS1 negative, which was confirmed with the enzyme linked immunosorbent assay method. For model development, 80 NS1 positive and 98 NS1 negative samples were used, while 40 DENV suspected samples were used for double blind testing of the model. This selection of samples was performed by the code in an automatic manner to avoid biasing. A laser at 785 nm was used as the excitation source to acquire Raman spectra of samples with an integration time of 15 s. The multivariate model yields coefficients of regression at corresponding Raman shifts. These coefficients represent changes in the molecular structures associated with NS1 positive and negative samples. The analysis of the regression coefficients which differentiate NS1 positive and NS1 negative groups shows an increasing trend for phosphatidylinositol, ceramide, and amide-III, and a decreasing trend for thiocyanate in the DENV infected serum. The R-squared value of the model was found to be 0.91, which is clinically acceptable. The blind testing of 40 suspected samples yields an accuracy, sensitivity, and specificity of about 100% each.

  7. Non-structural protein NS3/NS3a is required for propagation of bluetongue virus in Culicoides sonorensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Bluetongue virus (BTV) causes non-contagious haemorrhagic disease in ruminants and is transmitted by Culicoides spp. biting midges. BTV encodes four non-structural proteins of which NS3/NS3a is functional in virus release. NS3/NS3a is not essential for in vitro virus replication. However...

  8. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    NASA Astrophysics Data System (ADS)

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-05-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry.

  9. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs).

    PubMed

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-01-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry. PMID:27181521

  10. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    PubMed Central

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-01-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry. PMID:27181521

  11. Designing symmetric polar direct drive implosions on the Omega laser facility

    NASA Astrophysics Data System (ADS)

    Krasheninnikova, Natalia S.; Cobble, James A.; Murphy, Thomas J.; Tregillis, Ian L.; Bradley, Paul A.; Hakel, Peter; Hsu, Scott C.; Kyrala, George A.; Obrey, Kimberly A.; Schmitt, Mark J.; Baumgaertel, Jessica A.; Batha, Steven H.

    2014-04-01

    Achieving symmetric capsule implosions with Polar Direct Drive [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004); R. S. Craxton et al., Phys. Plasmas 12, 056304 (2005); F. J. Marshall et al., J. Phys. IV France 133, 153-157 (2006)] has been explored during recent Defect Induced Mix Experiment campaign on the Omega facility at the Laboratory for Laser Energetics. To minimize the implosion asymmetry due to laser drive, optimized laser cone powers, as well as improved beam pointings, were designed using 3D radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 3, 2070 (1996)]. Experimental back-lit radiographic and self-emission images revealed improved polar symmetry and increased neutron yield which were in good agreement with 2D HYDRA simulations. In particular, by reducing the energy in Omega's 21.4° polar rings by 16.75%, while increasing the energy in the 58.9° equatorial rings by 8.25% in such a way as to keep the overall energy to the target at 16 kJ, the second Legendre mode (P2) was reduced by a factor of 2, to less than 4% at bang time. At the same time the neutron yield increased by 62%. The polar symmetry was also improved relative to nominal DIME settings by a more radical repointing of OMEGA's 42.0° and 58.9° degree beams, to compensate for oblique incidence and reduced absorption at the equator, resulting in virtually no P2 around bang time and 33% more yield.

  12. Designing symmetric polar direct drive implosions on the Omega laser facility

    SciTech Connect

    Krasheninnikova, Natalia S.; Cobble, James A.; Murphy, Thomas J.; Tregillis, Ian L.; Bradley, Paul A.; Hakel, Peter; Hsu, Scott C.; Kyrala, George A.; Obrey, Kimberly A.; Schmitt, Mark J.; Baumgaertel, Jessica A.; Batha, Steven H.

    2014-04-15

    Achieving symmetric capsule implosions with Polar Direct Drive [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004); R. S. Craxton et al., Phys. Plasmas 12, 056304 (2005); F. J. Marshall et al., J. Phys. IV France 133, 153–157 (2006)] has been explored during recent Defect Induced Mix Experiment campaign on the Omega facility at the Laboratory for Laser Energetics. To minimize the implosion asymmetry due to laser drive, optimized laser cone powers, as well as improved beam pointings, were designed using 3D radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 3, 2070 (1996)]. Experimental back-lit radiographic and self-emission images revealed improved polar symmetry and increased neutron yield which were in good agreement with 2D HYDRA simulations. In particular, by reducing the energy in Omega's 21.4° polar rings by 16.75%, while increasing the energy in the 58.9° equatorial rings by 8.25% in such a way as to keep the overall energy to the target at 16 kJ, the second Legendre mode (P{sub 2}) was reduced by a factor of 2, to less than 4% at bang time. At the same time the neutron yield increased by 62%. The polar symmetry was also improved relative to nominal DIME settings by a more radical repointing of OMEGA's 42.0° and 58.9° degree beams, to compensate for oblique incidence and reduced absorption at the equator, resulting in virtually no P{sub 2} around bang time and 33% more yield.

  13. The 6p3/2ns(J = 1,2) autoionizing states of barium

    NASA Astrophysics Data System (ADS)

    Li, S. B.; Dai, C. J.; Sun, W.; Xue, P.

    2001-06-01

    Using a three-step laser excitation scheme we have selectively excited the Ba 6p3/2ns(J = 1,2) autoionizing Rydberg states with different polarization configurations. The level energies and widths of Ba 6p3/2ns(J = 1) autoionizing states with n = 9-33 and 6p3/2ns(J = 2) autoionizing states with n = 9-20 are reported, most of which were observed for the first time. Their spectroscopic properties are discussed in detail. The experimental data are in good agreement with the theoretical analysis from the multichannel quantum defect theory.

  14. Ion Thermal Decoupling and Species Separation in Shock-Driven Implosions

    NASA Astrophysics Data System (ADS)

    Rinderknecht, Hans G.; Rosenberg, M. J.; Li, C. K.; Hoffman, N. M.; Kagan, G.; Zylstra, A. B.; Sio, H.; Frenje, J. A.; Gatu Johnson, M.; Séguin, F. H.; Petrasso, R. D.; Amendt, P.; Bellei, C.; Wilks, S.; Delettrez, J.; Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Meyerhofer, D. D.; Nikroo, A.

    2015-01-01

    Anomalous reduction of the fusion yields by 50% and anomalous scaling of the burn-averaged ion temperatures with the ion-species fraction has been observed for the first time in D 3He-filled shock-driven inertial confinement fusion implosions. Two ion kinetic mechanisms are used to explain the anomalous observations: thermal decoupling of the D and 3He populations and diffusive species separation. The observed insensitivity of ion temperature to a varying deuterium fraction is shown to be a signature of ion thermal decoupling in shock-heated plasmas. The burn-averaged deuterium fraction calculated from the experimental data demonstrates a reduction in the average core deuterium density, as predicted by simulations that use a diffusion model. Accounting for each of these effects in simulations reproduces the observed yield trends.

  15. X-ray power increase from symmetrized wire-array z-pinch implosions

    SciTech Connect

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

    1996-08-01

    A systematic experimental study of annular aluminum-wire z-pinches on the Saturn accelerator shows that, for the first time, the measured spatial characteristics and x-ray powers can approach those of two-dimensional, radiation-magneto-hydrodynamic simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual plasma wires to that of a continuous plasma shell, when the circumferential gap between wires in the array is reduced below 1.4+1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4 {+-}0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma shell regime, x-ray powers in excess of a factor of three over that generated in the plasma-wire region are measured.

  16. Ion thermal decoupling and species separation in shock-driven implosions.

    PubMed

    Rinderknecht, Hans G; Rosenberg, M J; Li, C K; Hoffman, N M; Kagan, G; Zylstra, A B; Sio, H; Frenje, J A; Gatu Johnson, M; Séguin, F H; Petrasso, R D; Amendt, P; Bellei, C; Wilks, S; Delettrez, J; Glebov, V Yu; Stoeckl, C; Sangster, T C; Meyerhofer, D D; Nikroo, A

    2015-01-16

    Anomalous reduction of the fusion yields by 50% and anomalous scaling of the burn-averaged ion temperatures with the ion-species fraction has been observed for the first time in D^{3}He-filled shock-driven inertial confinement fusion implosions. Two ion kinetic mechanisms are used to explain the anomalous observations: thermal decoupling of the D and ^{3}He populations and diffusive species separation. The observed insensitivity of ion temperature to a varying deuterium fraction is shown to be a signature of ion thermal decoupling in shock-heated plasmas. The burn-averaged deuterium fraction calculated from the experimental data demonstrates a reduction in the average core deuterium density, as predicted by simulations that use a diffusion model. Accounting for each of these effects in simulations reproduces the observed yield trends. PMID:25635549

  17. Ion Thermal Decoupling and Species Separation in Shock-Driven Implosions

    DOE PAGESBeta

    Rinderknecht, Hans G.; Rosenberg, M. J.; Li, C. K.; Hoffman, N. M.; Kagan, G.; Zylstra, A. B.; Sio, H.; Johnson, M. Gatu; Seguin, F. H.; Petrasso, R. D.; et al

    2015-01-14

    Anomalous reduction of the fusion yields by 50% and anomalous scaling of the burn-averaged ion temperatures with the ion-species fraction has been observed for the first time in DHe3-filled shock-driven inertial confinement fusion implosions. Two ion kinetic mechanisms are used to explain the anomalous observations: thermal decoupling of the D and He3 populations and diffusive species separation. The observed insensitivity of ion temperature to a varying deuterium fraction is shown to be a signature of ion thermal decoupling in shock-heated plasmas. The burn-averaged deuterium fraction calculated from the experimental data demonstrates a reduction in the average core deuterium density, asmore » predicted by simulations that use a diffusion model. Accounting for each of these effects in simulations reproduces the observed yield trends.« less

  18. Ion Thermal Decoupling and Species Separation in Shock-Driven Implosions

    SciTech Connect

    Rinderknecht, Hans G.; Rosenberg, M. J.; Li, C. K.; Hoffman, N. M.; Kagan, G.; Zylstra, A. B.; Sio, H.; Johnson, M. Gatu; Seguin, F. H.; Petrasso, R. D.; Amendt, P.; Bellei, C.; Wilks, S.; Delettrez, J.; Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Meyerhofer, D. D.; Nikroo, A.

    2015-01-14

    Anomalous reduction of the fusion yields by 50% and anomalous scaling of the burn-averaged ion temperatures with the ion-species fraction has been observed for the first time in DHe3-filled shock-driven inertial confinement fusion implosions. Two ion kinetic mechanisms are used to explain the anomalous observations: thermal decoupling of the D and He3 populations and diffusive species separation. The observed insensitivity of ion temperature to a varying deuterium fraction is shown to be a signature of ion thermal decoupling in shock-heated plasmas. The burn-averaged deuterium fraction calculated from the experimental data demonstrates a reduction in the average core deuterium density, as predicted by simulations that use a diffusion model. Accounting for each of these effects in simulations reproduces the observed yield trends.

  19. In-Flight Measurements of Capsule Adiabats in Laser Driven Spherical Implosions

    SciTech Connect

    Kritcher, A L; Doppner, T; Fortman, C; Ma, T; Landen, O L; Wallace, R; Glenzer, S H

    2011-03-07

    We present the first x-ray Thomson scattering measurements of temperature and density from spherically imploding matter. The shape of the Compton downscattered spectrum provides a first-principles measurement of the electron velocity distribution function, dependent on T{sub e} and the Fermi temperature T{sub F} {approx} n{sub e}{sup 2/3}. In flight compressions of Be and CH targets reach 6-13 times solid density, with T{sub e}/T{sub F} {approx} 0.4-0.7, resulting in minimum adiabats of {approx}1.6-2. These measurements are consistent with low-entropy implosions and predictions by simulations using radiation-hydrodynamic modeling.

  20. Ion temperature measurements in shock-driven implosions on OMEGA and the NIF

    NASA Astrophysics Data System (ADS)

    Sio, H.; Zylstra, A.; Rosenberg, M.; Waugh, C.; Rinderknecht, H.; Sinenian, N.; Manuel, M.; Casey, D.; Gatu Johnson, M.; Li, C. K.; Seguin, F.; Frenje, J.; Petrasso, R.; Glebov, V. Yu.; Radha, P. B.; Delettrez, J.; McKenty, P.; Stoeckl, C.; Sangster, T. C.; Pape, S.; Bionta, R.; MacKinnon, A.; Landen, O.; Kilkenny, J.; Nikroo, A.

    2011-10-01

    Y. KIM, H. HERMANN, LANL Shock-driven ``exploding pusher'' implosions are commonly used at the OMEGA and the NIF facilities as test platforms for calibrating and validating diagnostics. We present extensive data on temperatures in exploding pushers obtained through methods: measurement of Doppler broadening of fusion products (from both DD and D3He reactions), and measurement of temperature sensitive yield ratios of DD and D3He yields. Since burn-averaged nuclear observables depend on density and temperature gradients and the time evolution after the spherical shock collapse, it is not evident a priori that these methods measure the same Ti. We compare experimental results to both radiation hydrodynamics simulations and an analytic Guderley shock model. This work was supported in part by LLE, the NLUF, the FSC, the US DOE, LLNL, and GA.

  1. Fusion yield enhancement in magnetized laser-driven implosions.

    PubMed

    Chang, P Y; Fiksel, G; Hohenberger, M; Knauer, J P; Betti, R; Marshall, F J; Meyerhofer, D D; Séguin, F H; Petrasso, R D

    2011-07-15

    Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement fusion implosions on the OMEGA Laser Facility. A spherical CH target with a 10 atm D2 gas fill was imploded in a polar-drive configuration. A magnetic field of 80 kG was embedded in the target and was subsequently trapped and compressed by the imploding conductive plasma. As a result of the hot-spot magnetization, the electron radial heat losses were suppressed and the observed ion temperature and neutron yield were enhanced by 15% and 30%, respectively. PMID:21838372

  2. Shell trajectory measurements from direct-drive implosion experiments.

    PubMed

    Michel, D T; Sorce, C; Epstein, R; Whiting, N; Igumenshchev, I V; Jungquist, R; Froula, D H

    2012-10-01

    A technique to measure the shell trajectory in direct-drive inertial confinement fusion implosions is presented. The x-ray self emission of the target is measured with an x-ray framing camera. Optimized filtering limits the x-ray emission from the corona plasma, isolating a sharp intensity gradient very near the ablation surface. This enables one to measure the radius of the imploding shell with an accuracy better than 1 μm and to determine a 200-ps average velocity to better than 2%. PMID:23127037

  3. Understanding the stagnation and burn of implosions on NIF

    NASA Astrophysics Data System (ADS)

    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.

  4. Fusion Yield Enhancement in Magnetized Laser-Driven Implosions

    NASA Astrophysics Data System (ADS)

    Chang, P. Y.; Fiksel, G.; Hohenberger, M.; Knauer, J. P.; Betti, R.; Marshall, F. J.; Meyerhofer, D. D.; Séguin, F. H.; Petrasso, R. D.

    2011-07-01

    Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement fusion implosions on the OMEGA Laser Facility. A spherical CH target with a 10 atm D2 gas fill was imploded in a polar-drive configuration. A magnetic field of 80 kG was embedded in the target and was subsequently trapped and compressed by the imploding conductive plasma. As a result of the hot-spot magnetization, the electron radial heat losses were suppressed and the observed ion temperature and neutron yield were enhanced by 15% and 30%, respectively.

  5. Structural insight and flexible features of NS5 proteins from all four serotypes of Dengue virus in solution.

    PubMed

    Saw, Wuan Geok; Tria, Giancarlo; Grüber, Ardina; Subramanian Manimekalai, Malathy Sony; Zhao, Yongqian; Chandramohan, Arun; Srinivasan Anand, Ganesh; Matsui, Tsutomu; Weiss, Thomas M; Vasudevan, Subhash G; Grüber, Gerhard

    2015-11-01

    Infection by the four serotypes of Dengue virus (DENV-1 to DENV-4) causes an important arthropod-borne viral disease in humans. The multifunctional DENV nonstructural protein 5 (NS5) is essential for capping and replication of the viral RNA and harbours a methyltransferase (MTase) domain and an RNA-dependent RNA polymerase (RdRp) domain. In this study, insights into the overall structure and flexibility of the entire NS5 of all four Dengue virus serotypes in solution are presented for the first time. The solution models derived revealed an arrangement of the full-length NS5 (NS5FL) proteins with the MTase domain positioned at the top of the RdRP domain. The DENV-1 to DENV-4 NS5 forms are elongated and flexible in solution, with DENV-4 NS5 being more compact relative to NS5 from DENV-1, DENV-2 and DENV-3. Solution studies of the individual MTase and RdRp domains show the compactness of the RdRp domain as well as the contribution of the MTase domain and the ten-residue linker region to the flexibility of the entire NS5. Swapping the ten-residue linker between DENV-4 NS5FL and DENV-3 NS5FL demonstrated its importance in MTase-RdRp communication and in concerted interaction with viral and host proteins, as probed by amide hydrogen/deuterium mass spectrometry. Conformational alterations owing to RNA binding are presented. PMID:26527147

  6. Identification and characterization of two cleavage fragments from the Aquareovirus nonstructural protein NS80.

    PubMed

    Chen, Qingxiu; Zhang, Jie; Zhang, Fuxian; Guo, Hong; Fang, Qin

    2016-08-01

    Aquareovirus species vary with respect to pathogenicity, and the nonstructural protein NS80 of aquareoviruses has been implicated in the regulation of viral replication and assembly, which can form viral inclusion bodies (VIBs) and recruit viral proteins to its VIBs in infected cells. NS80 consists of 742 amino acids with a molecular weight of approximately 80 kDa. Interestingly, a short specific fragment of NS80 has also been detected in infected cells. In this study, an approximately 58-kDa product of NS80 was confirmed in various infected and transfected cells by immunoblotting analyses using α-NS80C. Mutational analysis and time course expression assays indicated that the accumulation of the 58-kDa fragment was related to time and infection dose, suggesting that the fragment is not a transient intermediate of protein degradation. Moreover, another smaller fragment with a molecular mass of approximately 22 kDa was observed in transfected and infected cells by immunoblotting with a specific anti-FLAG monoclonal antibody or α-NS80N, indicating that the 58- kDa polypeptide is derived from a specific cleavage site near the amino terminus of NS80. Additionally, different subcellular localization patterns were observed for the 22-kDa and 58-kDa fragments in an immunofluorescence analysis, implying that the two cleavage fragments of NS80 function differently in the viral life cycle. These results provide a basis for additional studies of the role of NS80 played in replication and particle assembly of the Aquareovirus. PMID:27279144

  7. The Herschel Planetary Nebula Survey (HerPlaNS)

    NASA Astrophysics Data System (ADS)

    Ueta, T.; Ladjal, D.; HerPlaNS Team

    2012-12-01

    The Herschel Planetary Nebula Survey (HerPlaNS, PI: T. Ueta) is one of the largest Herschel Open Time 1 program in which we explore the far-infrared aspects of 11 planetary nebulae (PNs) with the Herschel Space Observatory, exploiting its unprecedented capabilities in broadband photometry mapping, spectral mapping, and integral-field spectroscopy. We perform (1) deep PACS/SPIRE broadband mapping to account for the coldest dust component of the nebulae and determine the spatial distribution of the dusty haloes in the target PNs, (2) exhaustive PACS/SPIRE line mapping in far-IR atomic and molecular lines in two representative PNs to diagnose the energetics of the nebulae as a function of location in the nebulae, and (3) PACS/SPIRE spectral-energy-distribution spectroscopy at several positions in the target PNs to understand variations in the physical conditions as a function of location in the nebulae, to build a more complete picture of the interplay between the dust and gas components as a function of location in the nebulae. The HerPlaNS survey is distinguished from the existing guaranteed-time Key Program (KPGT), "Mass Loss of Evolved StarS" (MESS, PI: M. Groenewegen, including 10 PNs) by the extra dimension added by spectral mapping and integral-field spatio-spectroscopy that permit simultaneous probing of the gas and dust component in the target PNs. Through these investigations, we will consider the energetics of the entire gas-dust system as a function of location in the nebulae, which is a novel approach that has rarely been taken previously. HerPlaNS is conducted in collaboration with the Chandra Planetary Survey (ChanPlaNS, PI: J.H. Kastner) to furnish substantial PN data resources that would allow us—a community of PN astronomers—to tackle a multitude of unanswered issues in PN physics, from the shaping mechanisms of the nebulae to the energetics of the multi-phased gas-dust system surrounding the central white dwarf. These PN surveys, combined with

  8. Proton and Alpha Core Imaging of OMEGA D^3He Implosions

    NASA Astrophysics Data System (ADS)

    Petrasso, R. D.; Frenje, J. A.; Seguin, F. H.; Li, C. K.; Schwartz, B. E.; Stoeckl, C.; Radha, P. B.; Delettrez, J. A.; Meyerhofer, D. D.; Roberts, S.; Sangster, T. C.; Soures, J. M.

    2002-11-01

    Measurements of the nuclear burn region are important for investigating the extent of the burn, the presence of burn asymmetries, the effects of mix and thermal conduction on the burn region, and the accuracy of code predictions. Charged-fusion-product core images have been obtained at OMEGA for implosions of D^3He-filled capsules with both thin and thick shells. Using multiple pinholes, images are reconstructed from 3.0-MeV and 14.7-MeV protons and 3.6-MeV alphas. For thin-shell, all three particles escape at bang time and their images reflect the different burn regions for DD and D^3He reactions. In contrast, for thick-shell implosions, only the 14.7-MeV proton can penetrate the capsule ρR at bang time, and the burn region reflects the effects of compression and mix. At first shock coalescence, when the ρR is far below its peak value, all three particles may also escape from the capsule. As mix has been experimentally shown to be inconsequential at this instant, meaningful comparisons of 1-D simulations with experiments can be made. This work was supported in part by the U.S. DOE Office of Inertial Confinement Fusion (Grant number DE-FG03-99DP00300 and Cooperative Agreement number DE-FC03-92SF19460), LLE (subcontract P0410025G), and LLNL (subcontract B313975. (Petrasso: Visiting Senior Scientist at LLE.)

  9. Nonsmooth nonnegative matrix factorization (nsNMF).

    PubMed

    Pascual-Montano, Alberto; Carazo, J M; Kochi, Kieko; Lehmann, Dietrich; Pascual-Marqui, Roberto D

    2006-03-01

    We propose a novel nonnegative matrix factorization model that aims at finding localized, part-based, representations of nonnegative multivariate data items. Unlike the classical nonnegative matrix factorization (NMF) technique, this new model, denoted "nonsmooth nonnegative matrix factorization" (nsNMF), corresponds to the optimization of an unambiguous cost function designed to explicitly represent sparseness, in the form of nonsmoothness, which is controlled by a single parameter. In general, this method produces a set of basis and encoding vectors that are not only capable of representing the original data, but they also extract highly localized patterns, which generally lend themselves to improved interpretability. The properties of this new method are illustrated with several data sets. Comparisons to previously published methods show that the new nsNMF method has some advantages in keeping faithfulness to the data in the achieving a high degree of sparseness for both the estimated basis and the encoding vectors and in better interpretability of the factors. PMID:16526426

  10. Determination of pressure and density of shocklessly compressed beryllium through x-ray radiography of a magnetically driven cylindrical liner implosion

    NASA Astrophysics Data System (ADS)

    Lemke, R. W.; Martin, M. R.; McBride, R. D.; Davis, J.-P.; Knudson, M. D.

    2011-06-01

    High current, pulsed-power driven liner implosions can be used to produce extreme pressure states in condensed matter for equation of state (EOS) studies. The Z accelerator can deliver a current pulse to a cylindrical liner (tubular shell) that rises to a peak current of ~20 MA in ~100 ns; at peak current the magnetic pressure is ~28 Mbar on the surface of a liner with radius 0.15 cm. We discuss a semi-empirical technique for obtaining EOS data for a metallic solid, quasi-isentropically (shocklessly) compressed to multi-megabar pressure, through x-ray radiography of a high current, magnetically driven, cylindrical liner implosion. Results are presented from experiments on Z in which a solid beryllium (Be) liner is quasi-isentropically compressed by magnetic pressure. Radiographs of the liner are used in conjunction with hydrodynamic equations to determine density and pressure on the principal quasi-isentrope of solid Be to a peak pressure of 2.4 Mbar. Sandia is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-ACO4-94AL85000.

  11. NetSim Project contributions to ns-3

    Energy Science and Technology Software Center (ESTSC)

    2012-05-01

    ns-3 is an external (non-LLNL) open-source framework for modeling computer networks. The LLNL NetSim project uses the ns-3 framework to address specific questions in computer network design, operation, and security. As part of the NetSim work, we develop bug fixes, deature enhancements, and new capabilities for the ns-3 framework. The virtual package referenced here, ns-3-contrib, consists of those developments we have (or will) contribute back to the ns-3 project in source code form, for inclusionmore » in future releases of ns-3.« less

  12. Mass profile and instability growth measurements for 300-wire z-pinch implosions driven by 14-18, MA.

    SciTech Connect

    Cuneo, Michael Edward; Yu, Edmund P.; Nash, Thomas J.; Bliss, David Emery; Porter, John Larry, Jr.; Sinars, Daniel Brian

    2004-07-01

    We present the first comprehensive study of high wire-number, wire-array Z-pinch dynamics at 14-18 MA using x-ray backlighting and optical shadowgraphy diagnostics. The cylindrical arrays retain slowly expanding, dense wire cores at the initial position up to 60% of the total implosion time. Azimuthally correlated instabilities at the array edge appear during this stage which continue to grow in amplitude and wavelength after the start of bulk motion, resulting in measurable trailing mass that does not arrive on axis before peak x-ray emission.

  13. Modeling and diagnosing interface mix in layered ICF implosions

    NASA Astrophysics Data System (ADS)

    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.

  14. Development of an accelerating-piston implosion-driven launcher

    NASA Astrophysics Data System (ADS)

    Huneault, Justin; Loiseau, Jason; Higgins, Andrew

    2013-06-01

    The ability to soft-launch projectiles at velocities exceeding 10 km/s is of interest to several scientific fields, including orbital debris impact testing and equation of state research. Current soft-launch technologies have reached a performance plateau below this operating range. The energy and power density of high explosives provides a possible avenue to reach this velocity if used to dynamically compress a light driver gas to significantly higher pressures and temperatures compared to light-gas guns. In the implosion-driven launcher (IDL), linear implosion of a pressurized tube drives a strong shock into the gas ahead of the tube pinch, thereby forming an increasingly long column of compressed gas which can be used to propel a projectile. The McGill IDL has demonstrated the ability to launch a 0.1-g projectile to 9.1 km/s. This study focuses on the implementation of a novel launch cycle wherein the explosively driven pinch is accelerated down the length of the tube in order to maintain a relatively constant projectile base pressure early in the launch cycle. The experimental development of an accelerating driver which utilizes an explosive lens to phase the detonation wave is presented. The design and experimental performance of an accelerating-piston IDL is also discussed.

  15. Hot spot conditions achieved in DT implosions on the NIF

    NASA Astrophysics Data System (ADS)

    Patel, P. K.; Callahan, D. A.; Cerjan, C.; Clark, D. S.; Dittrich, T. R.; Doeppner, T.; Edwards, M. J.; Haan, S.; Hinkel, D. E.; Berzak Hopkins, L. F.; Hurricane, O. A.; Kritcher, A. L.; Lindl, J. D.; Ma, T.; Macphee, A. G.; Pak, A. E.; Park, H. S.; Robey, H. F.; Salmonson, J. D.; Spears, B.; Springer, P. T.; Izumi, N.; Khan, S.

    2014-10-01

    We describe a 1D model that uses experimentally measured data to derive the thermodynamic conditions at stagnation of the hot spot, dense fuel, and ablator, in deuterium-tritium (DT) layered implosions on the National Ignition Facility (NIF). Neutron measurements--spectrally, spatially and temporally resolved--are used to infer the hot spot burn-averaged pressure, density, areal density, ion temperature, volume, and internal energy. X-ray spectral measurements are used to infer electron temperature, radiative energy loss, and the presence of ablator mix in the hot spot. In addition, we can calculate the fraction of alpha-particle energy trapped in the hot spot and, hence, estimate the degree of self-heating. Recent DT layered implosions using the high-foot design [Hurricane et al., Nature 506, 343 (2014)] have achieved areal densities and temperatures in the hot spot whereby a significant fraction of the internal energy at stagnation can be attributed to alpha-particle self-heating. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Hybrid-drive implosion system for ICF targets

    DOEpatents

    Mark, James W.

    1988-01-01

    Hybrid-drive implosion systems (20,40) for ICF targets (10,22,42) are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator (12) surroundingly disposed around fusion fuel (14). The ablator is first compressed to higher density by a laser system (24), or by an ion beam system (44), that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system (30,48) that is optimized for this second phase of operation of the target. The fusion fuel (14) is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion.

  17. Hybrid-drive implosion system for ICF targets

    DOEpatents

    Mark, J.W.K.

    1987-10-14

    Hybrid-drive implosion systems for ICF targets are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator surroundingly disposed around fusion fuel. The ablator is first compressed to higher density by a laser system, or by an ion beam system, that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system that is optimized for this second phase of operation of the target. The fusion fuel is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion. 3 figs.

  18. Hybrid-drive implosion system for ICF targets

    DOEpatents

    Mark, James W.

    1988-08-02

    Hybrid-drive implosion systems (20,40) for ICF targets (10,22,42) are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator (12) surroundingly disposed around fusion fuel (14). The ablator is first compressed to higher density by a laser system (24), or by an ion beam system (44), that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system (30,48) that is optimized for this second phase of operation of the target. The fusion fuel (14) is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion.

  19. Influence of atomic processes on the implosion of plasma liners

    SciTech Connect

    Kim, Hyoungkeun; Zhang Lina; Samulyak, Roman; Parks, Paul

    2012-08-15

    The influence of atomic physics processes on the implosion of plasma liners for magneto-inertial nuclear fusion has been investigated numerically by using the method of front tracking in spherically symmetric geometry and equation of state models accounting for dissociation and ionization. Simulation studies of the self-collapse of argon liners to be used in the Los Alamos Plasma Liner Experiment (PLX) program have been performed as well as studies of implosion of deuterium and argon liners on plasma targets. Results show that atomic processes in converging liners reduce the temperature of liners and increase the Mach number that results in the increase of the stagnation pressure and the fusion energy gain. For deuterium and argon liners imploding on plasma targets, dissociation and ionization increased the stagnation pressure and the fusion energy gain by the factor of 1.5 (deuterium) and 2 (argon) correspondingly. Similarly, ionization during the self-collapse of argon liners leads to approximately doubling of the Mach number and the stagnation pressure. The influence of the longitudinal density spread of the liner has also been investigated. The self-collapse stagnation pressure decreased by the factor of 8.7 when the initial position of the liner was shifted from the merging radius (33 cm) to the PLX chamber edge (137.2 cm). Simulations with and without the heat conduction demonstrated that the heat conduction has negligible effect on the self-collapse pressure of argon liners.

  20. Discovery of Dengue Virus NS4B Inhibitors

    PubMed Central

    Wang, Qing-Yin; Dong, Hongping; Zou, Bin; Karuna, Ratna; Wan, Kah Fei; Zou, Jing; Susila, Agatha; Yip, Andy; Shan, Chao; Yeo, Kim Long; Xu, Haoying; Ding, Mei; Chan, Wai Ling; Gu, Feng; Seah, Peck Gee; Liu, Wei; Lakshminarayana, Suresh B.; Kang, CongBao; Lescar, Julien; Blasco, Francesca; Smith, Paul W.

    2015-01-01

    results validate, for the first time, that NS4B inhibitors could potentially be developed for antiviral therapy for treatment of DENV infection in humans. PMID:26018165

  1. Shock implosion of a small homogeneous pellet

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yasuichi; Mishkin, Eli A.; Alejaldre, Carlos

    1985-10-01

    A small spherical, or cylindrical, pellet is imploded by an intensive, evenly distributed, short energy pulse. At the surface of the pellet the matter ionizes, its temperature and pressure rapidly rise, and the ablated plasma, by reaction, implodes the inner nucleus of the pellet. The involved structure of the energy absorbing zone is idealized and a sharp deflagration front is considered. With an almost square energy pulse, slightly dropping with time, the solution of the mass, momentum, and energy conservation equations of the compressed matter, is self-similar. The differential equation of the nondimensional position of the deflagration front, its integral, and the magnitude and shape of the outside energy pulse are derived. The process of ablation is shown to depend solely on the nondimensional velocity of the gas just ahead of the deflagration front, minus the speed of sound, or the ratio of the gas densities across the deflagration front.

  2. Resensitizing daclatasvir-resistant hepatitis C variants by allosteric modulation of NS5A.

    PubMed

    Sun, Jin-Hua; O'Boyle, Donald R; Fridell, Robert A; Langley, David R; Wang, Chunfu; Roberts, Susan B; Nower, Peter; Johnson, Benjamin M; Moulin, Frederic; Nophsker, Michelle J; Wang, Ying-Kai; Liu, Mengping; Rigat, Karen; Tu, Yong; Hewawasam, Piyasena; Kadow, John; Meanwell, Nicholas A; Cockett, Mark; Lemm, Julie A; Kramer, Melissa; Belema, Makonen; Gao, Min

    2015-11-12

    It is estimated that more than 170 million people are infected with hepatitis C virus (HCV) worldwide. Clinical trials have demonstrated that, for the first time in human history, the potential exists to eradicate a chronic viral disease using combination therapies that contain only direct-acting antiviral agents. HCV non-structural protein 5A (NS5A) is a multifunctional protein required for several stages of the virus replication cycle. NS5A replication complex inhibitors, exemplified by daclatasvir (DCV; also known as BMS-790052 and Daklinza), belong to the most potent class of direct-acting anti-HCV agents described so far, with in vitro activity in the picomolar (pM) to low nanomolar (nM) range. The potency observed in vitro has translated into clinical efficacy, with HCV RNA declining by ~3-4 log10 in infected patients after administration of single oral doses of DCV. Understanding the exceptional potency of DCV was a key objective of this study. Here we show that although DCV and an NS5A inhibitor analogue (Syn-395) are inactive against certain NS5A resistance variants, combinations of the pair enhance DCV potency by >1,000-fold, restoring activity to the pM range. This synergistic effect was validated in vivo using an HCV-infected chimaeric mouse model. The cooperative interaction of a pair of compounds suggests that NS5A protein molecules communicate with each other: one inhibitor binds to resistant NS5A, causing a conformational change that is transmitted to adjacent NS5As, resensitizing resistant NS5A so that the second inhibitor can act to restore inhibition. This unprecedented synergistic anti-HCV activity also enhances the resistance barrier of DCV, providing additional options for HCV combination therapy and new insight into the role of NS5A in the HCV replication cycle. PMID:26536115

  3. Solid Liner Implosions on Z for Producing Multi-Megabar, Shockless Compressions

    NASA Astrophysics Data System (ADS)

    Martin, Matthew

    2011-10-01

    Recent experiments with cylindrical liners on the Z-machine have utilized unshaped current drives where the early time drive pressure launches a shock into the initially solid liner. We explore the use of current pulse shaping techniques, originally developed for dynamic materials experiments on the Z-machine, to perform controlled cylindrical liner implosions. By driving the liner with a current pulse shape that prevents shock formation we avoid shock heating and melting the liner material and the corresponding decrease in electrical conductivity. This results in an imploding liner with a significant amount of its material in the solid phase and at multi-megabar pressures. Pressures in the solid region of a shaped pulse driven beryllium liner are expected to exceed 10 Mbar and have implosion velocities greater than 50 km/s. The solid liner experiments are diagnosed with multi-frame monochromatic X-ray backlighting which is used to infer the material density and pressure. These developments have lead to a new platform on the Z-machine that can be used to perform off-Hugoniot measurements at higher pressures than are accessible through magnetically driven planar geometries. This work was performed in collaboration with R.W. Lemke, R.D. McBride, M.D. Knudson, D.H. Dolan, and J P. Davis. Sandia is a multi-program laboratory operated by Sandia Corp, a Lockheed-Martin company, for the US Dept of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  4. First implosion experiments with cryogenic thermonuclear fuel on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Glenzer, Siegfried H.; Spears, Brian K.; Edwards, M. John; Alger, Ethan T.; Berger, Richard L.; Bleuel, Darren L.; Bradley, David K.; Caggiano, Joseph A.; Callahan, Debra A.; Castro, Carlos; Casey, Daniel T.; Choate, Christine; Clark, Daniel S.; Cerjan, Charles J.; Collins, Gilbert W.; Dewald, Eduard L.; Di Nicola, Jean-Michel G.; Di Nicola, Pascale; Divol, Laurent; Dixit, Shamasundar N.; Döppner, Tilo; Dylla-Spears, Rebecca; Dzenitis, Elizabeth G.; Fair, James E.; Frenje, Lars Johan Anders; Gatu Johnson, M.; Giraldez, E.; Glebov, Vladimir; Glenn, Steven M.; Haan, Steven W.; Hammel, Bruce A.; Hatchett, Stephen P., II; Haynam, Christopher A.; Heeter, Robert F.; Heestand, Glenn M.; Herrmann, Hans W.; Hicks, Damien G.; Holunga, Dean M.; Horner, Jeffrey B.; Huang, Haibo; Izumi, Nobuhiko; Jones, Ogden S.; Kalantar, Daniel H.; Kilkenny, Joseph D.; Kirkwood, Robert K.; Kline, John L.; Knauer, James P.; Kozioziemski, Bernard; Kritcher, Andrea L.; Kroll, Jeremy J.; Kyrala, George A.; LaFortune, Kai N.; Landen, Otto L.; Larson, Douglas W.; Leeper, Ramon J.; Le Pape, Sebastien; Lindl, John D.; Ma, Tammy; Mackinnon, Andrew J.; MacPhee, Andrew G.; Mapoles, Evan; McKenty, Patrick W.; Meezan, Nathan B.; Michel, Pierre; Milovich, Jose L.; Moody, John D.; Moore, Alastair S.; Moran, Mike; Moreno, Kari Ann; Munro, David H.; Nathan, Bryan R.; Nikroo, Abbas; Olson, Richard E.; Orth, Charles D.; Pak, Arthur; Patel, Pravesh K.; Parham, Tom; Petrasso, Richard; Ralph, Joseph E.; Rinderknecht, Hans; Regan, Sean P.; Robey, Harry F.; Ross, J. Steven; Salmonson, Jay D.; Sangster, Craig; Sater, Jim; Schneider, Marilyn B.; Séguin, F. H.; Shaw, Michael J.; Shoup, Milton J.; Springer, Paul T.; Stoeffl, Wolfgang; Suter, Larry J.; Avery Thomas, Cliff; Town, Richard P. J.; Walters, Curtis; Weber, Stephen V.; Wegner, Paul J.; Widmayer, Clay; Whitman, Pamela K.; Widmann, Klaus; Wilson, Douglas C.; Van Wonterghem, Bruno M.; MacGowan, Brian J.; Atherton, L. Jeff; Moses, Edward I.

    2012-04-01

    Non-burning thermonuclear fuel implosion experiments have been fielded on the National Ignition Facility to assess progress toward ignition by indirect drive inertial confinement fusion. These experiments use cryogenic fuel ice layers, consisting of mixtures of tritium and deuterium with large amounts of hydrogen to control the neutron yield and to allow fielding of an extensive suite of optical, x-ray and nuclear diagnostics. The thermonuclear fuel layer is contained in a spherical plastic capsule that is fielded in the center of a cylindrical gold hohlraum. Heating the hohlraum with 1.3 MJ of energy delivered by 192 laser beams produces a soft x-ray drive spectrum with a radiation temperature of 300 eV. The radiation field produces an ablation pressure of 100 Mbar which compresses the capsule to a spherical dense fuel shell that contains a hot plasma core 80 µm in diameter. The implosion core is observed with x-ray imaging diagnostics that provide size, shape, the absolute x-ray emission along with bangtime and hot plasma lifetime. Nuclear measurements provide the 14.1 MeV neutron yield from fusion of deuterium and tritium nuclei along with down-scattered neutrons at energies of 10-12 MeV due to energy loss by scattering in the dense fuel that surrounds the central hot-spot plasma. Neutron time-of-flight spectra allow the inference of the ion temperature while gamma-ray measurements provide the duration of nuclear activity. The fusion yield from deuterium-tritium reactions scales with ion temperature, which is in agreement with modeling over more than one order of magnitude to a neutron yield in excess of 1014 neutrons, indicating large confinement parameters on these first experiments. Part of the EPS 2011 special issue. Based on the plenary talk by S H Glenzer at the 38th EPS Plasma Physics meeting in Strassbourg, 2011.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Beryllium liner implosion experiments on the Z accelerator in preparation for Magnetized Liner Inertial Fusion (MagLIF)*

    NASA Astrophysics Data System (ADS)

    McBride, Ryan D.

    2012-10-01

    Magnetized Liner Inertial Fusion (MagLIF) [1] is a concept that involves using a pulsed electrical current to implode an initially-solid, cylindrical metal tube (liner) filled with preheated and magnetized fusion fuel. One- and two-dimensional simulations predict that if sufficient liner integrity can be maintained throughout the implosion, then significant fusion yield (>100 kJ) is possible on the 25-MA, 100-ns Z accelerator. The greatest threat to the liner integrity is the Magneto-Rayleigh-Taylor (MRT) instability, which first develops on the outer liner surface, and then works its way inward toward the inner surface throughout the implosion. Two-dimensional simulations predict that a thick liner, with Router/δR=6, should be robust enough to keep the MRT instability from overly disrupting the fusion burn at stagnation. This talk will present the first experiments designed to study a thick, MagLIF-relevant liner implosion through to stagnation on Z [2]. The use of beryllium for the liner material enabled us to obtain penetrating monochromatic (6151±0.5 eV) radiographs that reveal information about the entire volume of the imploding liner. This talk will also discuss experiments that investigated Z's pulse-shaping capabilities to either shock- or shocklessly-compress the imploding liners [3], as well as our most recent experiments that used 2-micron-thick aluminum sleeves to provide high-contrast tracers for the positions and states of the inner surfaces of the imploding beryllium liners. The radiography data to be presented provide stringent constraints on the simulation tools used by the broader high energy density physics and inertial confinement fusion communities, where quantitative areal density measurements, particularly of convergent fusion targets, are relatively scarce. We will also present power-flow tests of the MagLIF load hardware as well as new micro-B-dot measurements of the azimuthal drive magnetic field that penetrates the initially vacuum

  7. Exponential yield sensitivity to long-wavelength asymmetries in three-dimensional simulations of inertial confinement fusion capsule implosions

    SciTech Connect

    Haines, Brian M.

    2015-08-15

    In this paper, we perform a series of high-resolution 3D simulations of an OMEGA-type inertial confinement fusion (ICF) capsule implosion with varying levels of initial long-wavelength asymmetries in order to establish the physical energy loss mechanism for observed yield degradation due to long-wavelength asymmetries in symcap (gas-filled capsule) implosions. These simulations demonstrate that, as the magnitude of the initial asymmetries is increased, shell kinetic energy is increasingly retained in the shell instead of being converted to fuel internal energy. This is caused by the displacement of fuel mass away from and shell material into the center of the implosion due to complex vortical flows seeded by the long-wavelength asymmetries. These flows are not fully turbulent, but demonstrate mode coupling through non-linear instability development during shell stagnation and late-time shock interactions with the shell interface. We quantify this effect by defining a separation lengthscale between the fuel mass and internal energy and show that this is correlated with yield degradation. The yield degradation shows an exponential sensitivity to the RMS magnitude of the long-wavelength asymmetries. This strong dependence may explain the lack of repeatability frequently observed in OMEGA ICF experiments. In contrast to previously reported mechanisms for yield degradation due to turbulent instability growth, yield degradation is not correlated with mixing between shell and fuel material. Indeed, an integrated measure of mixing decreases with increasing initial asymmetry magnitude due to delayed shock interactions caused by growth of the long-wavelength asymmetries without a corresponding delay in disassembly.

  8. A cytotoxic nonstructural protein, NS1, of human parvovirus B19 induces activation of interleukin-6 gene expression.

    PubMed Central

    Moffatt, S; Tanaka, N; Tada, K; Nose, M; Nakamura, M; Muraoka, O; Hirano, T; Sugamura, K

    1996-01-01

    We examined the biological function of a nonstructural regulatory protein, NS1, of human parvovirus B19. Because of the cytotoxic activity of NS1, human hematopoietic cell lines, K562, Raji, and THP-1, were established as transfectants which produce the viral NS1 protein upon induction by using bacterial lactose repressor/operator system. NS1 was significantly produced in the three transfectant cells in an inducer dose- and time-dependent manner. Surprisingly, these three transfectants secreted an inflammatory cytokine, interleukin-6 (IL-6), in response to induction. However, no production of other related cytokines, IL-1beta, IL-8, or tumor necrosis factor alpha, was seen. Moreover, NS1-primed IL-6 induction was transiently demonstrated in primary human endothelial cells. Analysis with luciferase reporter plasmids carrying IL-6 promoter mutant fragments demonstrated that NS1 effect is mediated by a NF-kappaB binding site in the IL-6 promoter region, strongly implying that NS1 functions as a trans-acting transcriptional activator on the IL-6 promoter. Our novel finding, IL-6 induction by NS1, supports the possible relationship between parvovirus B19 infection and polyclonal activation of B cells in rheumatoid arthritis and indicates that NS1 protein may play a significant role in the pathogenesis of some B19-associated diseases by modulating the expression of host cellular genes. PMID:8970971

  9. Purification and crystallization of dengue and West Nile virus NS2B–NS3 complexes

    SciTech Connect

    D’Arcy, Allan Chaillet, Maxime; Schiering, Nikolaus; Villard, Frederic; Lim, Siew Pheng; Lefeuvre, Peggy; Erbel, Paul

    2006-02-01

    Crystals of dengue serotype 2 and West Nile virus NS2B–NS3 protease complexes have been obtained and the crystals of both diffract to useful resolution. Sample homogeneity was essential for obtaining X-ray-quality crystals of the dengue protease. Controlled proteolysis produced a crystallizable fragment of the apo West Nile virus NS2B–NS3 and crystals were also obtained in the presence of a peptidic inhibitor. Both dengue and West Nile virus infections are an increasing risk to humans, not only in tropical and subtropical areas, but also in North America and parts of Europe. These viral infections are generally transmitted by mosquitoes, but may also be tick-borne. Infection usually results in mild flu-like symptoms, but can also cause encephalitis and fatalities. Approximately 2799 severe West Nile virus cases were reported this year in the United States, resulting in 102 fatalities. With this alarming increase in the number of West Nile virus infections in western countries and the fact that dengue virus already affects millions of people per year in tropical and subtropical climates, there is a real need for effective medicines. A possible therapeutic target to combat these viruses is the protease, which is essential for virus replication. In order to provide structural information to help to guide a lead identification and optimization program, crystallizations of the NS2B–NS3 protease complexes from both dengue and West Nile viruses have been initiated. Crystals that diffract to high resolution, suitable for three-dimensional structure determinations, have been obtained.

  10. 25 ns software correlator for photon and fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Magatti, Davide; Ferri, Fabio

    2003-02-01

    A 25 ns time resolution, multi-tau software correlator developed in LABVIEW based on the use of a standard photon counting unit, a fast timer/counter board (6602-PCI National Instrument) and a personal computer (PC) (1.5 GHz Pentium 4) is presented and quantitatively discussed. The correlator works by processing the stream of incoming data in parallel according to two different algorithms: For large lag times (τ⩾100 μs), a classical time-mode (TM) scheme, based on the measure of the number of pulses per time interval, is used; differently, for τ⩽100 μs a photon-mode (PM) scheme is adopted and the time sequence of the arrival times of the photon pulses is measured. By combining the two methods, we developed a system capable of working out correlation functions on line, in full real time for the TM correlator and partially in batch processing for the PM correlator. For the latter one, the duty cycle depends on the count rate of the incoming pulses, being ˜100% for count rates ⩽3×104 Hz, ˜15% at 105 Hz, and ˜1% at 106 Hz. For limitations imposed by the fairly small first-in, first-out (FIFO) buffer available on the counter board, the maximum count rate permissible for a proper functioning of the PM correlator is limited to ˜105 Hz. However, this limit can be removed by using a board with a deeper FIFO. Similarly, the 25 ns time resolution is only limited by maximum clock frequency available on the 6602-PCI and can be easily improved by using a faster clock. When tested on dilute solutions of calibrated latex spheres, the overall performances of the correlator appear to be comparable with those of commercial hardware correlators, but with several nontrivial advantages related to its flexibility, low cost, and easy adaptability to future developments of PC and data acquisition technology.

  11. Strong HCV NS3/4a, NS4b, NS5a, NS5b-specific cellular immune responses induced in Rhesus macaques by a novel HCV genotype 1a/1b consensus DNA vaccine

    PubMed Central

    Latimer, Brian; Toporovski, Roberta; Yan, Jian; Pankhong, Panyupa; Morrow, Matthew P; Khan, Amir S; Sardesai, Niranjan Y; Welles, Seth L; Jacobson, Jeffrey M; Weiner, David B; Kutzler, Michele A

    2014-01-01

    Chronic HCV is a surreptitious disease currently affecting approximately 3% of the world's population that can lead to liver failure and cancer decades following initial infection. However, there are currently no vaccines available for the prevention of chronic HCV. From patients who acutely resolve HCV infection, it is apparent that a strong and broad cytotoxic T lymphocyte (CTL) response is important in HCV clearance. DNA vaccines are naked plasmid DNA molecules that encode pathogen antigens to induce a pathogen-specific immune response. They are inexpensive to produce and have an excellent safety profile in animals and humans. Additionally, DNA vaccines are able to induce strong CTL responses, making them well-suited for an HCV vaccine. We aimed to maximize vaccine recipients' opportunity to induce a broad T cell response with a novel antigenic sequence, multi-antigen vaccine strategy. We have generated DNA plasmids encoding consensus sequences of HCV genotypes 1a and 1b non-structural proteins NS3/4a, NS4b, NS5a, and NS5b. Rhesus macaques were used to study the immunogenicity of these constructs. Four animals were immunized 3 times, 6 weeks apart, at a dose of 1.0mg per antigen construct, as an intramuscular injection followed by in vivo electroporation, which greatly increases DNA uptake by local cells. Immune responses were measured 2 weeks post-immunization regimen (PIR) in immunized rhesus macaques and showed a broad response to multiple HCV nonstructural antigens, with up to 4680 spot-forming units per million peripheral blood mononuclear cells (PBMCs) as measured by Interferon-γ ELISpot. In addition, multiparametric flow cytometry detected HCV-specific CD4+ and CD8+ T cell responses by intracellular cytokine staining and detected HCV-specific CD107a+/GrzB+ CD8+ T cells indicating an antigen specific cytolytic response 2 weeks PIR compared with baseline measurements. At the final study time point, 6 weeks PIR, HCV-specific CD45RA- memory-like T cells

  12. Early-Time Symmetry Tuning in the Presence of Cross-Beam Energy Transfer in ICF Experiments on the National Ignition Facility

    DOE PAGESBeta

    Dewald, E. L.; Milovich, J. L.; Michel, P.; Landen, O. L.; Kline, J. L.; Glenn, S.; Jones, O.; Kalantar, D. H.; Pak, A.; Robey, H. F.; et al

    2013-12-01

    At the National Ignition Facility (NIF) we have successfully tuned the early time (~2 ns) lowest order Legendre mode (P2) of the incoming radiation drive asymmetry of indirectly driven ignition capsule implosions by varying the inner power cone fraction. The measured P2/P0 sensitivity vs come fraction is similar to calculations, but a significant -15 to -20% P2/P0 offset was observed. This can be explained by a considerable early time laser energy transfer from the outer to the inner beams during the laser burn-through of the Laser Entrance Hole (LEH) windows and hohlraum fill gas when the LEH plasma is stillmore » dense and relatively cold.« less

  13. Early-Time Symmetry Tuning in the Presence of Cross-Beam Energy Transfer in ICF Experiments on the National Ignition Facility

    SciTech Connect

    Dewald, E. L.; Milovich, J. L.; Michel, P.; Landen, O. L.; Kline, J. L.; Glenn, S.; Jones, O.; Kalantar, D. H.; Pak, A.; Robey, H. F.; Kyrala, G. A.; Divol, L.; Benedetti, L. R.; Holder, J.; Widmann, K.; Moore, A.; Schneider, M. B.; Döppner, T.; Tommasini, R.; Bradley, D. K.; Bell, P.; Ehrlich, B.; Thomas, C. A.; Shaw, M.; Widmayer, C.; Callahan, D. A.; Meezan, N. B.; Town, R. P. J.; Hamza, A.; Dzenitis, B.; Nikroo, A.; Moreno, K.; Van Wonterghem, B.; Mackinnon, A. J.; Glenzer, S. H.; MacGowan, B. J.; Kilkenny, J. D.; Edwards, M. J.; Atherton, L. J.; Moses, E. I.

    2013-12-01

    At the National Ignition Facility (NIF) we have successfully tuned the early time (~2 ns) lowest order Legendre mode (P2) of the incoming radiation drive asymmetry of indirectly driven ignition capsule implosions by varying the inner power cone fraction. The measured P2/P0 sensitivity vs come fraction is similar to calculations, but a significant -15 to -20% P2/P0 offset was observed. This can be explained by a considerable early time laser energy transfer from the outer to the inner beams during the laser burn-through of the Laser Entrance Hole (LEH) windows and hohlraum fill gas when the LEH plasma is still dense and relatively cold.

  14. PVDF water-shock pressure transducer with 200-ns response

    SciTech Connect

    Johnson, D.E.; Hogeland, S.R.; Nelson, L.S.

    1992-12-01

    The design, calibration, and preliminary test results for an underwater shock gauge are presented. The active element is a 25-{mu}m thick polyvinylidene fluoride shock sensor providing rise times as short as 50 ns. Fast rise time is essential to accurate recording of shock pulses with durations of only a few microseconds. The piezoelectric polymer provides a self-generating pressure sensor requiring neither amplification nor additional active electronic circuitry. The gauge package is designed to minimize electromagnetic interference from the high-voltage fire set used to power the exploding bridge wire pressure source. The gauge package is constructed to withstand the initial water shock as well as subsequent reactions in the water that result in strong water motion and bubble generation. Thin-film diaphragm sensors are not sturdy enough to withstand this environment. Initial tests show that the gauge responds in 200 ns in water and that low-frequency response is sufficient to allow recording for at least 40 {mu}s after the initial shock arrival.

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

    NASA Astrophysics Data System (ADS)

    Ling, Jiajie; Bishai, Mary; Diwan, Milind; Dolph, Jeffrey; Kettell, Steve; Sexton, Kenneth; Sharma, Rahul; Simos, Nikolaos; Stewart, James; Tanaka, Hidekazu; Viren, Brett; Arnold, Douglas; Tabor, Philip; Turner, Stephen; Benson, Terry; Wahl, Daniel; Wendt, Christopher; Hahn, Alan; Kaducak, Marc; Mantsch, Paul; Sundaram, S. K.

    2013-11-01

    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&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.

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

    SciTech Connect

    Cray, M.; Delamater, N.D.; Fernandez, J.C.

    1994-09-01

    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. Direct-driven target implosion in heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Noguchi, K.; Suzuki, T.; Kurosaki, T.; Barada, D.; Kawata, S.; Ma, Y. Y.; Ogoyski, A. I.

    2016-03-01

    In inertial confinement fusion, the driver beam illumination non-uniformity leads a degradation of fusion energy output. A fuel target alignment error would happen in a fusion reactor; the target alignment error induces heavy ion beam illumination non-uniformity on a target. On the other hand, heavy ion beam accelerator provides a capability to oscillate a beam axis with a high frequency. The wobbling beams may provide a new method to reduce or smooth the beam illumination non-uniformity. First we study the effect of driver irradiation non-uniformity induced by the target alignment error (dz) on the target implosion. We found that dz should be less than about 130 μm for a sufficient fusion energy output. We also optimize the wobbling scheme. The spiral wobbling heavy ion beams would provide a promissing scheme to the uniform beam illumination.

  18. Three-dimensional simulations of Nova capsule implosion experiments

    SciTech Connect

    Marinak, M.M.; Tipton, R.E.; Landen, O.L.

    1995-11-01

    Capsule implosion experiments carried out on the Nova laser are simulated with the three-dimensional HYDRA radiation hydrodynamics code. Simulations of ordered near single mode perturbations indicate that structures which evolve into round spikes can penetrate farthest into the hot spot. Bubble-shaped perturbations can burn through the capsule shell fastest, however, causing even more damage. Simulations of a capsule with multimode perturbations shows spike amplitudes evolving in good agreement with a saturation model during the deceleration phase. The presence of sizable low mode asymmetry, caused either by drive asymmetry or perturbations in the capsule shell, can dramatically affect the manner in which spikes approach the center of the hot spot. Three-dimensional coupling between the low mode shell perturbations intrinsic to Nova capsules and the drive asymmetry brings the simulated yields into closer agreement with the experimental values.

  19. 2013 East Bay Seismic Experiment (EBSE): implosion data, Hayward, Calif

    USGS Publications Warehouse

    Catchings, Rufus D.; Strayer, Luther M.; Goldman, Mark R.; Criley, Coyn J.; Garcia, Susan; Sickler, Robert R.; Catchings, Marisol K.; Chan, Joanne; Gordon, Leslie C.; Haefner, Scott; Blair, James Luke; Gandhok, Gini; Johnson, Michaela R.

    2015-01-01

    In August 2013, the California State University, East Bay (CSUEB) in Hayward, California imploded a 13-story building (Warren Hall) that was deemed unsafe because of its immediate proximity to the active trace of the Hayward Fault. The U.S. Geological Survey (USGS) and the CSUEB collaborated on a program to record the seismic waves generated by the collapse of the building. We refer to this collaboration as the East Bay Seismic Experiment (EBSE). The principal objective of recording the seismic energy was to observe ground shaking as it radiated from the source, but the data also may be useful for other purposes. For example, the seismic data may be useful in evaluating the implosion process as it relates to structural engineering purposes. This report provides the metadata needed to utilize the seismic data.

  20. Modeling Z-Pinch implosions in two dimensions

    SciTech Connect

    Peterson, D.; Bowers, R.; Brownell, J.

    1997-12-31

    Ideally, simulations of Z-Pinch implosions should provide useful information about important physics processes underlying observed experimental results and provide design capabilities for future experiments. With this goal the authors have developed a methodology for simulating hollow Z-Pinches in two dimensions and applied it to experiments conducted on the Pegasus I and Pegasus II capacitor banks, the Procyon explosion generator system, and the Saturn and PBFA-Z accelerators. In comparisons with experimental results the simulations have reproduced important features of the current drive, spectrum, radiation pulse shape, peak power and total radiated energy. Comparison of the instability development in the simulations with visible light framing camera photos has shown a close correlation with the observed instability wavelengths and amplitudes. Using this methodology the authors are analyzing recent Saturn and PBFA-Z experiments and applying the 2-D modeling in developing applications such as the dynamic hohlraum.

  1. Plasma flow switch and foil implosion experiments on Pegasus II

    SciTech Connect

    Cochrane, J.C.; Bartsch, R.R.; Benage, J.R.; Forman, P.R.; Gribble, R.F.; Ladish, J.S.; Oona, H.; Parker, J.V.; Scudder, D.W.; Shlachter, J.S.; Wysocki, F.J.

    1993-01-01

    Pegasus II is the upgraded version of Pegasus, a pulsed power machine used in the Los Alamos AGEX (Above Ground EXperiments) program. A goal of the program is to produce an intense (> 100 TW) source of soft x-rays from the thermalization of the kinetic energy of a 1 to 10 MJ plasma implosion. The radiation pulse should have a maximum duration of several 10's of nanoseconds and will be used in the study of fusion conditions and material properties. The radiating plasma source will be generated by the thermalization of the kinetic energy of an imploding cylindrical, thin, metallic foil. This paper addresses experiments done on a capacitor bank to develop a switch (plasma flow switch) to switch the bank current into the load at peak current. This allows efficient coupling of bank energy into foil kinetic energy.

  2. Plasma flow switch and foil implosion experiments on Pegasus II

    SciTech Connect

    Cochrane, J.C.; Bartsch, R.R.; Benage, J.R.; Forman, P.R.; Gribble, R.F.; Ladish, J.S.; Oona, H.; Parker, J.V.; Scudder, D.W.; Shlachter, J.S.; Wysocki, F.J.

    1993-07-01

    Pegasus II is the upgraded version of Pegasus, a pulsed power machine used in the Los Alamos AGEX (Above Ground EXperiments) program. A goal of the program is to produce an intense (> 100 TW) source of soft x-rays from the thermalization of the kinetic energy of a 1 to 10 MJ plasma implosion. The radiation pulse should have a maximum duration of several 10`s of nanoseconds and will be used in the study of fusion conditions and material properties. The radiating plasma source will be generated by the thermalization of the kinetic energy of an imploding cylindrical, thin, metallic foil. This paper addresses experiments done on a capacitor bank to develop a switch (plasma flow switch) to switch the bank current into the load at peak current. This allows efficient coupling of bank energy into foil kinetic energy.

  3. Direct-drive DT implosions with Knudsen number variations

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Magnetic Implosion for Novel Strength Measurements at High Strain Rates

    SciTech Connect

    Lee, H.; Preston, D.L.; Bartsch, R.R.; Bowers, R.L.; Holtkamp, D.; Wright, B.L.

    1998-10-19

    Recently Lee and Preston have proposed to use magnetic implosions as a new method for measuring material strength in a regime of large strains and high strain rates inaccessible to previously established techniques. By its shockless nature, this method avoids the intrinsic difficulties associated with an earlier approach using high explosives. The authors illustrate how the stress-strain relation for an imploding liner can be obtained by measuring the velocity and temperature history of its inner surface. They discuss the physical requirements that lead us to a composite liner design applicable to different test materials, and also compare the code-simulated prediction with the measured data for the high strain-rate experiments conducted recently at LANL. Finally, they present a novel diagnostic scheme that will enable us to remove the background in the pyrometric measurement through data reduction.

  6. Mean free path effects in the shock-implosion problem

    NASA Astrophysics Data System (ADS)

    Goldsworthy, M. J.; Pullin, D. I.

    2009-02-01

    The effects of finite Knudsen number in the problem of a cylindrically imploding shock wave in a monatomic gas are investigated. Numerical solutions of the flow field are obtained with initial conditions in the ranges 1.25≤M0≤5 and 0.005≤Kn0≤0.1 using the direct simulation Monte Carlo method. Results show that as Kn0 decreases and M0 increases, the maximum implosion temperature scales increasingly well with the similarity exponent predicted in the Guderley solution for an imploding strong shock in the Euler limit. When the radius of curvature is large, the cylindrical shock thickness is found to be almost identical to the thickness of a planar shock for a given shock Mach number. For small radii of curvature, the cylindrical shock was found to be thicker than the corresponding planar shock.

  7. Evidence of Systematic Jetting in Nominal Omega Implosions

    NASA Astrophysics Data System (ADS)

    Shah, Rahul; Haines, B. M.; Wysocki, F. J.; Hakel, P.; Kagan, G.; Murphy, T. J.; Benage, J. F.; Mancini, R. C.; Glebov, V.; Marshall, F. J.; Michel, D. T.; Stoeckl, C.; Yaakobi, B.

    2015-11-01

    By means of detailed comparison between narrow-spectrum tracer-emission-images and 2-D radiation-hydrodynamic calculation, we present evidence of a systematic hydrodynamic defect of nominal OMEGA implosions. The defect, which arises from a drive asymmetry caused by capsule mounting, distorts the low-mode symmetry and pressure profile of the fuel cavity and also enhances deceleration-phase fuel-shell mixing. It is a critical consideration for interpretations of performance degradation (and for analyses dependent on shape assumptions). The tracer technique is predicted to differentiate the change in fuel cavity structure between the existing and a proposed improvement of the capsule mounting. The influence of the defect on the fuel-shell mixing is also shown to be an essential consideration for analysis of separated reactants experiments.

  8. Exploration of the Transition from the Hydrodynamiclike to the Strongly Kinetic Regime in Shock-Driven Implosions

    NASA Astrophysics Data System (ADS)

    Rosenberg, M. J.; Rinderknecht, H. G.; Hoffman, N. M.; Amendt, P. A.; Atzeni, S.; Zylstra, A. B.; Li, C. K.; Séguin, F. H.; Sio, H.; Johnson, M. Gatu; Frenje, J. A.; Petrasso, R. D.; Glebov, V. Yu.; Stoeckl, C.; Seka, W.; Marshall, F. J.; Delettrez, J. A.; Sangster, T. C.; Betti, R.; Goncharov, V. N.; Meyerhofer, D. D.; Skupsky, S.; Bellei, C.; Pino, J.; Wilks, S. C.; Kagan, G.; Molvig, K.; Nikroo, A.

    2014-05-01

    Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar DHe3 gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ˜2 at 3.1 mg /cm3 to a factor of 100 at 0.14 mg /cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.

  9. Observation of early shell-dopant mix in OMEGA direct-drive implosions and comparisons with radiation-hydrodynamic simulations

    SciTech Connect

    Baumgaertel, J. A.; Bradley, P. A.; Hsu, S. C.; Cobble, J. A.; Hakel, P.; Tregillis, I. L.; Krasheninnikova, N. S.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Obrey, K. D.; Batha, S.; Johns, H.; Joshi, T.; Mayes, D.; Mancini, R. C.; Nagayama, T.

    2014-05-15

    Temporally, spatially, and spectrally resolved x-ray image data from direct-drive implosions on OMEGA were interpreted with the aid of radiation-hydrodynamic simulations. Neither clean calculations nor those using a turbulent mix model can explain fully the observed migration of shell-dopant material (titanium) into the core. Shell-dopant migration was observed via time-dependent, spatially integrated spectra, and spatially and spectrally resolved x-ray images of capsule implosions and resultant dopant emissions. The titanium emission was centrally peaked in narrowband x-ray images. In post-processed clean simulations, the peak titanium emission forms in a ring in self-emission images as the capsule implodes. Post-processed simulations with mix reproduce trends in time-dependent, spatially integrated spectra, as well having centrally peaked Ti emission in synthetic multiple monochromatic imager. However, mix simulations still do not transport Ti to the core as is observed in the experiment. This suggests that phenomena in addition to the turbulent mix must be responsible for the transport of Ti. Simple diffusion estimates are unable to explain the early Ti mix into the core. Mechanisms suggested for further study are capsule surface roughness, illumination non-uniformity, and shock entrainment.

  10. Exploration of the Transition from the Hydrodynamic-like to the Strongly Kinetic Regime in Shock-Driven Implosions

    DOE PAGESBeta

    Rosenberg, M. J.; Rinderknecht, H. G.; Hoffman, N. M.; Amendt, P. A.; Atzeni, S.; Zylstra, A. B.; Li, C. K.; Seguin, F. H.; Sio, H.; Johnson, M. Gatu; et al

    2014-05-05

    Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly over-predict the observed nuclear yields, from a factor of ~2 at 3.1 mg/cm3 to a factor of 100 at 0.14 mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of meritmore » of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.« less

  11. Exploration of the Transition from the Hydrodynamic-like to the Strongly Kinetic Regime in Shock-Driven Implosions

    SciTech Connect

    Rosenberg, M. J.; Rinderknecht, H. G.; Hoffman, N. M.; Amendt, P. A.; Atzeni, S.; Zylstra, A. B.; Li, C. K.; Seguin, F. H.; Sio, H.; Johnson, M. Gatu; Frenje, J. A.; Petrasso, R. D.; Glebov, V. Yu.; Stoeckl, C.; Seka, W.; Marshall, F. J.; Delettrez, J. A.; Sangster, T. C.; Betti, R.; Goncharov, V. N.; Meyerhofer, D. D.; Skupsky, S.; Bellei, C.; Pino, J.; Wilks, S. C.; Kagan, G.; Molvig, K.; Nikroo, A.

    2014-05-05

    Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly over-predict the observed nuclear yields, from a factor of ~2 at 3.1 mg/cm3 to a factor of 100 at 0.14 mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.

  12. Development of the CD symcap platform to study gas-shell mix in implosions at the National Ignition Facility

    DOE PAGESBeta

    Casey, D. T.; Smalyuk, V. A.; Tipton, R. E.; Pino, J. E.; Grim, G. P.; Remington, B. A.; Rowley, D. P.; Weber, S. V.; Barrios, M.; Benedetti, L. R.; et al

    2014-09-09

    Surrogate implosions play an important role at the National Ignition Facility (NIF) for isolating aspects of the complex physical processes associated with fully integrated ignition experiments. The newly developed CD Symcap platform has been designed to study gas-shell mix in indirectly driven, pure T₂-gas filled CH-shell implosions equipped with 4 μm thick CD layers. This configuration provides a direct nuclear signature of mix as the DT yield (above a characterized D contamination background) is produced by D from the CD layer in the shell, mixing into the T-gas core. The CD layer can be placed at different locations within themore » CH shell to probe the depth and extent of mix. CD layers placed flush with the gas-shell interface and recessed up to 8 μm have shown that most of the mix occurs at the inner-shell surface. In addition, time-gated x-ray images of the hotspot show large brightly-radiating objects traversing through the hotspot around bang-time, which are likely chunks of CH/CD plastic. This platform is a powerful new capability at the NIF for understanding mix, one of the key performance issues for ignition experiments.« less

  13. Development of the CD symcap platform to study gas-shell mix in implosions at the National Ignition Facility

    SciTech Connect

    Casey, D. T.; Smalyuk, V. A.; Tipton, R. E.; Pino, J. E.; Grim, G. P.; Remington, B. A.; Rowley, D. P.; Weber, S. V.; Barrios, M.; Benedetti, L. R.; Bleuel, D. L.; Bond, E. J.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Cerjan, C. J.; Chen, K. C.; Edgell, D. H.; Edwards, M. J.; Fittinghoff, D.; Frenje, J. A.; Gatu-Johnson, M.; Glebov, V. Y.; Glenn, S.; Guler, N.; Haan, S. W.; Hamza, A.; Hatarik, R.; Herrmann, H. W.; Hoover, D.; Hsing, W. W.; Izumi, N.; Kervin, P.; Khan, S.; Kilkenny, J. D.; Kline, J.; Knauer, J.; Kyrala, G.; Landen, O. L.; Ma, T.; MacPhee, A. G.; McNaney, J. M.; Mintz, M.; Moore, A.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R.; Rinderknecht, H. G.; Sayre, D. B.; Schneider, M.; Stoeffl, W.; Tommasini, R.; Town, R. P.; Widmann, K.; Wilson, D. C.; Yeamans, C. B.

    2014-09-09

    Surrogate implosions play an important role at the National Ignition Facility (NIF) for isolating aspects of the complex physical processes associated with fully integrated ignition experiments. The newly developed CD Symcap platform has been designed to study gas-shell mix in indirectly driven, pure T₂-gas filled CH-shell implosions equipped with 4 μm thick CD layers. This configuration provides a direct nuclear signature of mix as the DT yield (above a characterized D contamination background) is produced by D from the CD layer in the shell, mixing into the T-gas core. The CD layer can be placed at different locations within the CH shell to probe the depth and extent of mix. CD layers placed flush with the gas-shell interface and recessed up to 8 μm have shown that most of the mix occurs at the inner-shell surface. In addition, time-gated x-ray images of the hotspot show large brightly-radiating objects traversing through the hotspot around bang-time, which are likely chunks of CH/CD plastic. This platform is a powerful new capability at the NIF for understanding mix, one of the key performance issues for ignition experiments.

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

    NASA Astrophysics Data System (ADS)

    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< 17 and fuel adiabat α > 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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Klem, Michael

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Progress in modelling ignition implosion experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The recently completed National Ignition Campaign on the National Ignition Facility showed significant discrepancies between 2-D simulations predictions of implosion performance and experimentally measured performance, particularly in thermonuclear yield. This discrepancy between simulation and observation persisted despite concerted efforts to include all of the known sources of implosion degradation within a reasonable 2-D simulation model, e.g., using measured surface imperfections and radiation drives adjusted to reproduce observed implosion trajectories. Since this simulation study was undertaken, more recent experiments have brought to light several effects that can significantly impact implosion performance, in particular large inflight long-wavelength shell asymmetries and larger than expected perturbations seeded by the capsule support tent. These effects are now being included in the simulation model and show improved agreement with observation. In addition, full-capsule 3-D simulations with resolution adequate to model the dominant unstable hydrodynamic modes are being run and show further improvements in agreement with experiment.

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

    NASA Astrophysics Data System (ADS)

    Mostert, W.; Wheatley, V.; Samtaney, R.; Pullin, D. I.

    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.

  20. Hepatitis C Virus NS2 Protein Triggers Endoplasmic Reticulum Stress and Suppresses its Own Viral Replication

    PubMed Central

    von dem Bussche, Annette; Machida, Raiki; Li, Ke; Loevinsohn, Gideon; Khander, Amrin; Wang, Jianguo; Wakita, Takaji; Wands, Jack R.; Li, Jisu

    2010-01-01

    Background & Aims We previously reported that the NS2 protein of hepatitis C virus (HCV) inhibits the expression of reporter genes driven by a variety of cellular and viral promoters. The aim of the study was to determine whether the broad transcriptional repression is caused by endoplasmic reticulum (ER) stress. Methods Phosphorylation of the translation initiation factor eIF2α and HCV replication were detected by Western and Northern blot, respectively. De novo protein synthesis was measured by metabolic labeling. Activation of ER stress responsive genes was determined by promoter reporter assay, as well as mRNA and protein measurement by real time PCR and Western blot. Results Transient or inducible NS2 protein expression increased eIF2α phosphorylation and reduced de novo protein synthesis. It up-regulated promoter activities and transcript levels of ER stress inducible genes including GRP78, ATF6, and GADD153, as well as GRP78 protein level. The same effect was observed when NS2 was synthesized as part of the core-E1-E2-p7-NS2 polypeptide. NS2 protein also inhibited reporter gene expression from the HCV internal ribosome entry site and consequently reduced HCV replication. The full-length HCV replicon activated GRP78, ATF6, and GADD153 promoters more efficiently than the subgenomic replicon lacking the coding sequence for both the structural proteins and NS2. Abrogation of HCV infection/replication, by an inhibitor of the NS3 protease, relieved ER stress. Conclusions HCV infection can induce ER stress, with NS2 protein being a major mediator. The stress can be relieved by a feedback mechanism. PMID:20801537

  1. Ebselen Inhibits Hepatitis C Virus NS3 Helicase Binding to Nucleic Acid and Prevents Viral Replication

    PubMed Central

    2015-01-01

    The hepatitis C virus (HCV) nonstructural protein 3 (NS3) is both a protease, which cleaves viral and host proteins, and a helicase that separates nucleic acid strands, using ATP hydrolysis to fuel the reaction. Many antiviral drugs, and compounds in clinical trials, target the NS3 protease, but few helicase inhibitors that function as antivirals have been reported. This study focuses on the analysis of the mechanism by which ebselen (2-phenyl-1,2-benzisoselenazol-3-one), a compound previously shown to be a HCV antiviral agent, inhibits the NS3 helicase. Ebselen inhibited the abilities of NS3 to unwind nucleic acids, to bind nucleic acids, and to hydrolyze ATP, and about 1 μM ebselen was sufficient to inhibit each of these activities by 50%. However, ebselen had no effect on the activity of the NS3 protease, even at 100 times higher ebselen concentrations. At concentrations below 10 μM, the ability of ebselen to inhibit HCV helicase was reversible, but prolonged incubation of HCV helicase with higher ebselen concentrations led to irreversible inhibition and the formation of covalent adducts between ebselen and all 14 cysteines present in HCV helicase. Ebselen analogues with sulfur replacing the selenium were just as potent HCV helicase inhibitors as ebselen, but the length of the linker between the phenyl and benzisoselenazol rings was critical. Modifications of the phenyl ring also affected compound potency over 30-fold, and ebselen was a far more potent helicase inhibitor than other, structurally unrelated, thiol-modifying agents. Ebselen analogues were also more effective antiviral agents, and they were less toxic to hepatocytes than ebselen. Although the above structure–activity relationship studies suggest that ebselen targets a specific site on NS3, we were unable to confirm binding to either the NS3 ATP binding site or nucleic acid binding cleft by examining the effects of ebselen on NS3 proteins lacking key cysteines. PMID:25126694

  2. Development of 5Ns chromosome-specific SCAR markers for utilization in future wheat breeding programs.

    PubMed

    Wang, J; Wang, L M; Du, W L; Chen, L G; Liu, S H; Wu, J; Zhao, J X; Yang, Q H; Chen, X H

    2014-06-01

    In previous studies, we developed a wheat-Psathyrostachys huashanica Keng disomic addition line 3-8-10-2, which exhibited high stripe rust resistance and could be used as a donor source for introducing novel disease resistance gene(s) into wheat in future breeding programs. It was identified using cytology, genomic in situ hybridization (GISH), EST-SSR, EST-STS and morphological analyses. However, these techniques are not suitable for breeding programs that require the rapid screening of large numbers of genotypes because they are highly technical and time-consuming. In this study, three Ns genome-specific SCAR markers were developed via random amplified polymorphic DNA (RAPD) markers. These SCAR markers were further validated using a complete set of wheat-P. huashanica disomic addition lines, which segregated the 5Ns disomic addition line individuals. Our results indicated that the SCAR markers associated with the 5Ns chromosome of P. huashanica and they provide a low cost, high efficiency, alternative tool for screening 5Ns chromosomes in a wheat background. These newly developed SCAR markers that species-specificity of the markers was proved by analysis of a wide range of cereal species, and specific for 5Ns chromosome, which should be useful in marker-assisted selection for wheat breeders who want to screen genotypes that may contain 5Ns chromatin. PMID:25715460

  3. Influenza A Virus Attenuation by Codon Deoptimization of the NS Gene for Vaccine Development

    PubMed Central

    Nogales, Aitor; Baker, Steven F.; Ortiz-Riaño, Emilio; Dewhurst, Stephen; Topham, David J.

    2014-01-01

    (NS) gene of influenza virus encodes both the multifunctional nonstructural protein 1 (NS1), essential for innate immune evasion, and the nuclear export protein (NEP), required for the nuclear export of viral ribonucleoproteins and for timing of the virus life cycle. Here, we have generated a recombinant influenza A/Puerto Rico/8/1934 (H1N1) (PR8) virus containing a codon-deoptimized NS segment that is attenuated in vivo yet retains immunogenicity and protection efficacy against homologous and heterologous influenza virus challenges. These results open the exciting possibility of using this NS codon deoptimization methodology alone or in combination with other approaches for the future development of vaccine candidates to prevent influenza viral infections. PMID:24965472

  4. Three-dimensional simulations of the implosion of inertial confinement fusion targets

    SciTech Connect

    Town, R.P.J.; Bell, A.R. )

    1991-09-30

    The viability of inertial confinement fusion depends crucially on implosion symmetry. A spherical three-dimensional hydrocode called PLATO has been developed to model the growth in asymmetries during an implosion. Results are presented in the deceleration phase which show indistinguishable linear growth rates, but greater nonlinear growth of the Rayleigh-Taylor instability than is found in two-dimensional cylindrical simulations. The three-dimensional enhancement of the nonlinear growth is much smaller than that found by Sakagami and Nishihara.

  5. Tuning the implosion symmetry of ICF targets via controlled crossed-beam energy transfer

    SciTech Connect

    Michel, P; Divol, L; Williams, E; Weber, S; Thomas, C A; Callahan, D A; Haan, S W; Salmonson, J D; Dixit, S; Hinkel, D E; Edwards, M J; MacGowan, B J; Lindl, J D; Glenzer, S H; Suter, L

    2008-07-29

    Radiative hydrodynamics simulations of ignition experiments show that energy transfer between crossing laser beams allows tuning of the implosion symmetry. A new full-scale, three dimensional quantitative model has been developed for crossed-beam energy transfer, allowing calculations of the propagation and coupling of multiple laser beams and their associated plasma waves in ignition hohlraums. This model has been implemented in a radiative-hydrodynamics code, demonstrating control of the implosion symmetry by a wavelength separation between cones of laser beams.

  6. Determinants of Dengue Virus NS4A Protein Oligomerization

    PubMed Central

    Lee, Chia Min; Xie, Xuping; Zou, Jing; Li, Shi-Hua; Lee, Michelle Yue Qi; Dong, Hongping; Qin, Cheng-Feng; Kang, Congbao

    2015-01-01

    ABSTRACT Flavivirus NS4A protein induces host membrane rearrangement and functions as a replication complex component. The molecular details of how flavivirus NS4A exerts these functions remain elusive. Here, we used dengue virus (DENV) as a model to characterize and demonstrate the biological relevance of flavivirus NS4A oligomerization. DENV type 2 (DENV-2) NS4A protein forms oligomers in infected cells or when expressed alone. Deletion mutagenesis mapped amino acids 50 to 76 (spanning the first transmembrane domain [TMD1]) of NS4A as the major determinant for oligomerization, while the N-terminal 50 residues contribute only slightly to the oligomerization. Nuclear magnetic resonance (NMR) analysis of NS4A amino acids 17 to 80 suggests that residues L31, L52, E53, G66, and G67 could participate in oligomerization. Ala substitution for 15 flavivirus conserved NS4A residues revealed that these amino acids are important for viral replication. Among the 15 mutated NS4A residues, 2 amino acids (E50A and G67A) are located within TMD1. Both E50A and G67A attenuated viral replication, decreased NS4A oligomerization, and reduced NS4A protein stability. In contrast, NS4A oligomerization was not affected by the replication-defective mutations (R12A, P49A, and K80A) located outside TMD1. trans complementation experiments showed that expression of wild-type NS4A alone was not sufficient to rescue the replication-lethal NS4A mutants. However, the presence of DENV-2 replicons could partially restore the replication defect of some lethal NS4A mutants (L26A and K80A), but not others (L60A and E122A), suggesting an unidentified mechanism governing the outcome of complementation in a mutant-dependent manner. Collectively, the results have demonstrated the importance of TMD1-mediated NS4A oligomerization in flavivirus replication. IMPORTANCE We report that DENV NS4A forms oligomers. Such NS4A oligomerization is mediated mainly through amino acids 50 to 76 (spanning the first

  7. Mode 1 drive asymmetry in inertial confinement fusion implosions on the National Ignition Facility

    SciTech Connect

    Spears, Brian K. Edwards, M. J.; Hatchett, S.; Kritcher, A.; Lindl, J.; Munro, D.; Patel, P.; Robey, H. F.; Town, R. P. J.; Kilkenny, J.; Knauer, J.

    2014-04-15

    Mode 1 radiation drive asymmetry (pole-to-pole imbalance) at significant levels can have a large impact on inertial confinement fusion implosions at the National Ignition Facility (NIF). This asymmetry distorts the cold confining shell and drives a high-speed jet through the hot spot. The perturbed hot spot shows increased residual kinetic energy and reduced internal energy, and it achieves reduced pressure and neutron yield. The altered implosion physics manifests itself in observable diagnostic signatures, especially the neutron spectrum which can be used to measure the neutron-weighted flow velocity, apparent ion temperature, and neutron downscattering. Numerical simulations of implosions with mode 1 asymmetry show that the resultant simulated diagnostic signatures are moved toward the values observed in many NIF experiments. The diagnostic output can also be used to build a set of integrated implosion performance metrics. The metrics indicate that P{sub 1} has a significant impact on implosion performance and must be carefully controlled in NIF implosions.

  8. Framed X-Ray Imaging of Cryogenic Target Implosion Cores on Omega

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.; Goncharov, V. N.; Glebov, V. Yu.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.

    2015-11-01

    Cryogenic DT target implosions being performed on the OMEGA Laser System are now being diagnosed by two high-speed x-ray framing cameras (~ 30-ps frame times) able to time- and space-resolve the evolving high-pressure stagnating plasma core. One high-speed framing camera is coupled to a pinhole array and is able to image the core emission every 15 ps with ~ 16- μm spatial resolution. It can accurately measure the time of x-ray emission peak and duration. The other framing camera is coupled to a novel 16-image Kirkpatrick-Baez (KB)-type x-ray optic providing ~ 7- μm spatial resolution and can also sample the emission with images spaced in time by as little as ~ 15 ps. The core emission size determined from the framed KB images at the peak of stagnation allows for inferences of core pressure when combined with measurements of the ion temperature, burnwidth, and neutron yield. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  9. Characterization of influenza virus NS1 protein by using a novel helper-virus-free reverse genetic system.

    PubMed

    Enami, M; Enami, K

    2000-06-01

    We have developed a novel helper-virus-free reverse genetic system to genetically manipulate influenza A viruses. The RNPs, which were purified from the influenza A/WSN/33 (WSN) virus, were treated with RNase H in the presence of NS (nonstructural) cDNA fragments. This specifically digested the NS RNP. The NS-digested RNPs thus obtained were transfected into cells together with the in vitro-reconstituted NS RNP. The NS-digested RNPs alone did not rescue viruses; however, cotransfection with the NS RNP did. This protocol was also used to rescue the NP transfectant. We obtained two NS1 mutants, dl12 and N110, using this protocol. The dl12 NS gene contains a deletion of 12 amino acids at positions 66 to 77 near the N terminus. This virus was temperature sensitive in Madin-Darby bovine kidney (MDBK) cells as well as in Vero cells. The translation of all viral proteins as well as cellular proteins was significantly disrupted during a later time of infection at the nonpermissive temperature of 39 degrees C. The N110 mutant consists of 110 amino acids which are the N-terminal 48% of the WSN virus NS1 protein. Growth of this virus was significantly reduced at any temperature. In the virus-infected cells, translation of the M1 protein was reduced to 10 to 20% of that of the wild-type virus; however, the translation of neither the nucleoprotein nor NS1 was significantly interfered with, indicating the important role of NS1 in translational stimulation of the M1 protein. PMID:10823862

  10. Inferring Low-Mode Asymmetries from the Elastically Scattered Neutron Spectrum in Layered Cryogenic DT Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Forrest, C. J.; Glebov, V. Yu.; Goncharov, V. N.; Sangster, T. C.; Stoeckl, C.; Frenje, J. A.; Gatu Johnson, M.

    2014-10-01

    High-resolution neutron spectroscopy is used to probe the areal density of layered cryogenic DT direct-drive implosions in inertial confinement fusion experiments on OMEGA. Advanced scintillation detectors record the neutron spectrum using time-of-flight techniques. The shape of the energy spectrum is fully determined by the neutron elastic scattering cross-section for spherically symmetric target configurations. Significant differences from the expected shape have been measured for some recent implosions, which indicate a deviation from a spherically symmetric fuel assembly. Neutron scattering with low-mode perturbations in the DT fuel assembly have been simulated in the Monte Carlo n-particle transport code. The experimental data shows good agreement with the model when the mass distribution of the compressed DT shell is highly asymmetric with one side having a factor-of-2 higher areal density. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. A Numerical Model for Two-Plasmon-Decay Hot-Electron Production and Mitigation in Direct-Drive Implosions

    NASA Astrophysics Data System (ADS)

    Myatt, J. F.; Shaw, J. G.; Solodov, A. A.; Maximov, A. V.; Short, R. W.; Seka, W.; Follett, R. K.; Edgell, D. H.; Froula, D. H.; Goncharov, V. N.

    2015-11-01

    Hot-electron preheat, caused by laser-plasma instabilities, can impair the performance of inertial confinement fusion implosions. It is therefore imperative to understand processes that can generate hot electrons and to design mitigation strategies should preheat be found to be excessive at the ignition scale (laser-plasma interactions do not follow hydrodynamic scaling). For this purpose, a new 3-D model [laser-plasma simulation environment (LPSE)] has been constructed that computes hot-electron generation in direct-drive plasmas based on the assumption that two-plasmon decay is the dominant, hot-electron-producing instability. It uses an established model of TPD-driven turbulence together with a new GPU based hybrid particle method of hot-electron production. The time-dependent hot-electron power, total energy, and energy spectrum are computed and compared with data from recent OMEGA implosion experiments that have sought to mitigate TPD by the use of multilayered (mid- Z) ablators. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Hybrid simulation of the Z-pinch instabilities for profiles generated during wire array implosion in the Saturn pulsed power generator

    SciTech Connect

    Sotnikov, V.I.; Leboeuf, J.N.; Deeney, C.; Coverdale, C.A.; Hellinger, P.; Travnicek, P.; Fiala, V.

    2005-09-15

    Experimental evidence suggests that the energy balance between processes in play during wire array implosions is not well understood. In fact the radiative yields can exceed by several times the implosion kinetic energy. A possible explanation is that the coupling from magnetic energy to kinetic energy as magnetohydrodynamic plasma instabilities develop provides additional energy. It is thus important to model the instabilities produced in the after implosion stage of the wire array in order to determine how the stored magnetic energy can be connected with the radiative yields. To this aim three-dimensional hybrid simulations have been performed. They are initialized with plasma radial density profiles, deduced in recent experiments [C. Deeney et al., Phys. Plasmas 6, 3576 (1999)] that exhibited large x-ray yields, together with the corresponding magnetic field profiles. Unlike previous work, these profiles do not satisfy pressure balance and differ substantially from those of a Bennett equilibrium. They result in faster growth with an associated transfer of magnetic energy to plasma motion and hence kinetic energy.

  15. Hybrid simulation of the Z-pinch instabilities for profiles generated in the process of wire array implosion in the Saturn pulsed power generator.

    SciTech Connect

    Coverdale, Christine Anne; Travnicek, P.; Hellinger, P.; Fiala, V.; Leboeuf, J. N.; Deeney, Christopher; Sotnikov, Vladimir Isaakovich

    2005-02-01

    Experimental evidence suggests that the energy balance between processes in play during wire array implosions is not well understood. In fact the radiative yields can exceed by several times the implosion kinetic energy. A possible explanation is that the coupling from magnetic energy to kinetic energy as magnetohydrodynamic plasma instabilities develop provides additional energy. It is thus important to model the instabilities produced in the after implosion stage of the wire array in order to determine how the stored magnetic energy can be connected with the radiative yields. To this aim three-dimensional hybrid simulations have been performed. They are initialized with plasma radial density profiles, deduced in recent experiments [C. Deeney et al., Phys. Plasmas 6, 3576 (1999)] that exhibited large x-ray yields, together with the corresponding magnetic field profiles. Unlike previous work, these profiles do not satisfy pressure balance and differ substantially from those of a Bennett equilibrium. They result in faster growth with an associated transfer of magnetic energy to plasma motion and hence kinetic energy.

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

    NASA Astrophysics Data System (ADS)

    Temporal, M.; Canaud, B.; Garbett, W. J.; Ramis, R.

    2015-10-01

    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.

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

    SciTech Connect

    Temporal, M.; Canaud, B.; Garbett, W. J.; Ramis, R.

    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.

  18. Effect of the mounting membrane on shape in inertial confinement fusion implosions

    SciTech Connect

    Nagel, S. R. Haan, S. W.; Rygg, J. R.; Barrios, M.; Benedetti, L. R.; Bradley, D. K.; Field, J. E.; Hammel, B. A.; Izumi, N.; Jones, O. S.; Khan, S. F.; Ma, T.; Pak, A. E.; Tommasini, R.; Town, R. P. J.

    2015-02-15

    The performance of Inertial Confinement Fusion targets relies on the symmetric implosion of highly compressed fuel. X-ray area-backlit imaging is used to assess in-flight low mode 2D asymmetries of the shell. These time-resolved images of the shell exhibit features that can be related to the lift-off position of the membranes used to hold the capsule within the hohlraum. Here, we describe a systematic study of this membrane or “tent” thickness and its impact on the measured low modes for in-flight and self-emission images. The low mode amplitudes of the shell in-flight shape (P{sub 2} and P{sub 4}) are weakly affected by the tent feature in time-resolved, backlit data. By contrast, time integrated self-emission images along the same axis exhibit a reversal in perceived P{sub 4} mode due to growth of a feature seeded by the tent, which can explain prior inconsistencies between the in-flight P{sub 4} and core P{sub 4}, leading to a reevaluation of optimum hohlraum length. Simulations with a tent-like feature normalized to match the feature seen in the backlit images predict a very large impact on the capsule performance from the tent feature.

  19. Changes of ns-soot mixing states and shapes in an urban area during CalNex

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Buseck, Peter R.

    2013-05-01

    Aerosol particles from megacities influence the regional and global climate as well as the health of their occupants. We used transmission electron microscopes (TEMs) to study aerosol particles collected from the Los Angeles area during the 2010 CalNex campaign. We detected major amounts of ns-soot, defined as consisting of carbon nanospheres, sulfate, sea salt, and organic aerosol (OA) and lesser amounts of brochosome particles from leaf hoppers. Ns-soot-particle shapes, mixing states, and abundances varied significantly with sampling times and days. Within plumes having high CO2 concentrations, much ns-soot was compacted and contained a relatively large number of carbon nanospheres. Ns-soot particles from both CalNex samples and Mexico City, the latter collected in 2006, had a wide range of shapes when mixed with other aerosol particles, but neither sets showed spherical ns-soot nor the core-shell configuration that is commonly used in optical calculations. Our TEM observations and light-absorption calculations of modeled particles indicate that, in contrast to ns-soot particles that are embedded within other materials or have the hypothesized core-shell configurations, those attached to other aerosol particles hardly enhance their light absorption. We conclude that the ways in which ns-soot mixes with other particles explain the observations of smaller light amplification by ns-soot coatings than model calculations during the CalNex campaign and presumably in other areas.

  20. Aquareovirus NS80 Initiates Efficient Viral Replication by Retaining Core Proteins within Replication-Associated Viral Inclusion Bodies

    PubMed Central

    Yan, Liming; Zhang, Jie; Guo, Hong; Yan, Shicui; Chen, Qingxiu; Zhang, Fuxian; Fang, Qin

    2015-01-01

    Viral inclusion bodies (VIBs) are specific intracellular compartments for reoviruses replication and assembly. Aquareovirus nonstructural protein NS80 has been identified to be the major constituent for forming globular VIBs in our previous study. In this study, we investigated the role of NS80 in viral structural proteins expression and viral replication. Immunofluorescence assays showed that NS80 could retain five core proteins or inner-capsid proteins (VP1-VP4 and VP6), but not outer-capsid proteins (VP5 and VP7), within VIBs in co-transfected or infected cells. Further co-immunoprecipitation analysis confirmed that NS80 could interact with each core protein respectively. In addition, we found that newly synthesized viral RNAs co-localized with VIBs. Furthermore, time-course analysis of viral structural proteins expression showed that the expression of NS80 was detected first, followed by the detection of inner shell protein VP3, and then of other inner-capsid proteins, suggesting that VIBs were essential for the formation of viral core frame or progeny virion. Moreover, knockdown of NS80 by shRNA not only inhibited the expression of aquareovirus structural proteins, but also inhibited viral infection. These results indicated that NS80-based VIBs were formed at earlier stage of infection, and NS80 was able to coordinate the expression of viral structural proteins and viral replication. PMID:25938226

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

    SciTech Connect

    Goncharov, V. N.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Follett, R. K.; Forrest, C. J.; Froula, D. H.; Yu. Glebov, V.; Harding, D. R.; Henchen, R. J.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H.; Kessler, T. J.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; Maximov, A. V.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Nora, R.; Radha, P. B.; Regan, S. P.; Seka, W.; Shmayda, W. T.; Short, R.W.; Shvydky, A.; Skupsky, S.; Stoeckl, C.; Yaakobi, B.; Frenje, J. A.; Gatu-Johnson, M.; Petrasso, R. D.; Casey, D. T.

    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.

  2. Analysis of Radiation from Implosions of Stainless Steel Wire Arrays on Zebra and Comparison with Laser Plasma Experiments on Leopard at UNR*.

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Shrestha, I.; Shlyaptseva, V. V.; Weller, M. E.; Osborne, G. C.; Williamson, K. M.; Stafford, A.; Keim, S. F.; Faenov, A. Ya.; Esaulov, A. A.; Wiewior, P.; Legalloudec, N.; Paudel, Y.; Coverdale, C. A.; Chuvatin, A. S.

    2011-10-01

    The implosions of Stainless Steel (SS) Wire Arrays are extensively studied at SNL and also have applications in astrophysics. The analysis of radiation from low-number-wire SS Single and Nested Cylindrical, and Planar Wire Array experiments on the 1 MA Zebra is presented. The major focus is on x-ray imaging and spectra, total radiation yields, and fast, filtered x-ray detector data. The results of Leopard laser experiments with a flat 25 μm Fe target in the nanosecond (ns) and 350 femtosecond (fs) pulse regimes are discussed and compared with Z-pinch data. This comparison focuses mainly on L-shell Fe radiation and provides an excellent benchmark to the Z-pinch results. Good agreement with laser data is demonstrated in the ns regime, but a substantial difference is observed for the fs pulse. This work was supported by NNSA under DOE Coop. Agreements DE-FC52-06NA27588, 27586, and 27616. SNL is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Co., for the U.S. DOE under Contract DE-AC04-94AL85000.

  3. Dengue virus NS1 triggers endothelial permeability and vascular leak that is prevented by NS1 vaccination.

    PubMed

    Beatty, P Robert; Puerta-Guardo, Henry; Killingbeck, Sarah S; Glasner, Dustin R; Hopkins, Kaycie; Harris, Eva

    2015-09-01

    The four dengue virus serotypes (DENV1 to DENV4) are mosquito-borne flaviviruses that cause up to ~100 million cases of dengue annually worldwide. Severe disease is thought to result from immunopathogenic processes involving serotype cross-reactive antibodies and T cells that together induce vasoactive cytokines, causing vascular leakage that leads to shock. However, no viral proteins have been directly implicated in triggering endothelial permeability, which results in vascular leakage. DENV nonstructural protein 1 (NS1) is secreted and circulates in patients' blood during acute infection; high levels of NS1 are associated with severe disease. We show that inoculation of mice with DENV NS1 alone induces both vascular leakage and production of key inflammatory cytokines. Furthermore, simultaneous administration of NS1 with a sublethal dose of DENV2 results in a lethal vascular leak syndrome. We also demonstrate that NS1 from DENV1, DENV2, DENV3, and DENV4 triggers endothelial barrier dysfunction, causing increased permeability of human endothelial cell monolayers in vitro. These pathogenic effects of physiologically relevant amounts of NS1 in vivo and in vitro were blocked by NS1-immune polyclonal mouse serum or monoclonal antibodies to NS1, and immunization of mice with NS1 from DENV1 to DENV4 protected against lethal DENV2 challenge. These findings add an important and previously overlooked component to the causes of dengue vascular leak, identify a new potential target for dengue therapeutics, and support inclusion of NS1 in dengue vaccines. PMID:26355030

  4. Implications of PSR J0737-3039B for the Galactic NS-NS binary merger rate

    NASA Astrophysics Data System (ADS)

    Kim, Chunglee; Perera, Benetge Bhakthi Pranama; McLaughlin, Maura A.

    2015-03-01

    The Double Pulsar (PSR J0737-3039) is the only neutron star-neutron star (NS-NS) binary in which both NSs have been detectable as radio pulsars. The Double Pulsar has been assumed to dominate the Galactic NS-NS binary merger rate R_g among all known systems, solely based on the properties of the first-born, recycled pulsar (PSR J0737-3039A, or A) with an assumption for the beaming correction factor of 6. In this work, we carefully correct observational biases for the second-born, non-recycled pulsar (PSR J0737-0737B, or B) and estimate the contribution from the Double Pulsar on R_g using constraints available from both A and B. Observational constraints from the B pulsar favour a small beaming correction factor for A (˜2), which is consistent with a bipolar model. Considering known NS-NS binaries with the best observational constraints, including both A and B, we obtain R_g=21_{-14}^{+28} Myr-1 at 95 per cent confidence from our reference model. We expect the detection rate of gravitational waves from NS-NS inspirals for the advanced ground-based gravitational-wave detectors is to be 8^{+10}_{-5} yr-1 at 95 per cent confidence. Within several years, gravitational-wave detections relevant to NS-NS inspirals will provide us useful information to improve pulsar population models.

  5. NMR Analysis of a Novel Enzymatically Active Unlinked Dengue NS2B-NS3 Protease Complex*

    PubMed Central

    Kim, Young Mee; Gayen, Shovanlal; Kang, CongBao; Joy, Joma; Huang, Qiwei; Chen, Angela Shuyi; Wee, John Liang Kuan; Ang, Melgious Jin Yan; Lim, Huichang Annie; Hung, Alvin W.; Li, Rong; Noble, Christian G.; Lee, Le Tian; Yip, Andy; Wang, Qing-Yin; Chia, Cheng San Brian; Hill, Jeffrey; Shi, Pei-Yong; Keller, Thomas H.

    2013-01-01

    The dengue virus (DENV) is a mosquito-borne pathogen responsible for an estimated 100 million human infections annually. The viral genome encodes a two-component trypsin-like protease that contains the cofactor region from the nonstructural protein NS2B and the protease domain from NS3 (NS3pro). The NS2B-NS3pro complex plays a crucial role in viral maturation and has been identified as a potential drug target. Using a DENV protease construct containing NS2B covalently linked to NS3pro via a Gly4-Ser-Gly4 linker (“linked protease”), previous x-ray crystal structures show that the C-terminal fragment of NS2B is remote from NS3pro and exists in an open state in the absence of an inhibitor; however, in the presence of an inhibitor, NS2B complexes with NS3pro to form a closed state. This linked enzyme produced NMR spectra with severe signal overlap and line broadening. To obtain a protease construct with a resolved NMR spectrum, we expressed and purified an unlinked protease complex containing a 50-residue segment of the NS2B cofactor region and NS3pro without the glycine linker using a coexpression system. This unlinked protease complex was catalytically active at neutral pH in the absence of glycerol and produced dispersed cross-peaks in a 1H-15N heteronuclear single quantum correlation spectrum that enabled us to conduct backbone assignments using conventional techniques. In addition, titration with an active-site peptide aldehyde inhibitor and paramagnetic relaxation enhancement studies demonstrated that the unlinked DENV protease exists predominantly in a closed conformation in solution. This protease complex can serve as a useful tool for drug discovery against DENV. PMID:23511634

  6. A single-chip 32-channel analog beamformer with 4-ns delay resolution and 768-ns maximum delay range for ultrasound medical imaging with a linear array transducer.

    PubMed

    Um, Ji-Yong; Kim, Yoon-Jee; Cho, Seong-Eun; Chae, Min-Kyun; Kim, Byungsub; Sim, Jae-Yoon; Park, Hong-June

    2015-02-01

    A single-chip 32-channel analog beamformer is proposed. It achieves a delay resolution of 4 ns and a maximum delay range of 768 ns. It has a focal-point based architecture, which consists of 7 sub-analog beamformers (sub-ABF). Each sub-ABF performs a RX focusing operation for a single focal point. Seven sub-ABFs perform a time-interleaving operation to achieve the maximum delay range of 768 ns. Phase interpolators are used in sub-ABFs to generate sampling clocks with the delay resolution of 4 ns from a low frequency system clock of 5 MHz. Each sub-ABF samples 32 echo signals at different times into sampling capacitors, which work as analog memory cells. The sampled 32 echo signals of each sub-ABF are originated from one target focal point at one instance. They are summed at one instance in a sub-ABF to perform the RX focusing for the target focal point. The proposed ABF chip has been fabricated in a 0.13- μ m CMOS process with an active area of 16 mm (2). The total power consumption is 287 mW. In measurement, the digital echo signals from a commercial ultrasound medical imaging machine were applied to the fabricated chip through commercial DAC chips. Due to the speed limitation of the DAC chips, the delay resolution was relaxed to 10 ns for the real-time measurement. A linear array transducer with no steering operation is used in this work. PMID:25069119

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Simulations in One Dimension of Unstable Mix in Laser-Driven Implosion Experiments

    NASA Astrophysics Data System (ADS)

    Epstein, R.; Delettrez, J. A.; Bradley, D. K.; Verdon, C. P.

    1997-11-01

    The effects of Rayleigh-Taylor flow in recent laser-driven implosion experiments are simulated in one dimension by the hydrocode LILAC*. The adequacy of this mix model to account for the experimental results is examined. Mix is modeled as a diffusive transport process affecting material constituents, thermal energy, and turbulent mix-motion energy within a growing mix region whose boundaries are derived from a saturable, linear multimode model of the Rayleigh-Taylor instability. The linear growth rates and the feedthrough coupling between perturbations of different unstable interfaces are obtained analytically in terms of the one-dimensional fluid profiles. Two-dimensional simulations and experimental data are used to reduce the uncertainties in the adjustable parameters of the model. Mode evolution proceeds according to equations applicable to all phases of acceleration, and the effects of geometrically converging, compressible flow are taken into account. Simulated mix diagnostics include time-resolved spectra of x-ray emission from additives in the shell and in the fuel and time-resolved neutron production from CD layers in the shell. Spectra are simulated using a non-LTE radiation-transport post-processor that makes full use of the multi-material mix information. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  9. Inner-shell radiation from wire array implosions on the Zebra generator

    SciTech Connect

    Ouart, N. D.; Giuliani, J. L.; Dasgupta, A.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Shrestha, I.; Weller, M. E.; Shlyaptseva, V.; Osborne, G. C.; Stafford, A.; Keim, S.; Apruzese, J. P.; Clark, R. W.

    2014-03-15

    Implosions of brass wire arrays on Zebra have produced L-shell radiation as well as inner-shell Kα and Kβ transitions. The L-shell radiation comes from ionization stages around the Ne-like charge state that is largely populated by a thermal electron energy distribution function, while the K-shell photons are a result of high-energy electrons ionizing or exciting an inner-shell (1s) electron from ionization stages around Ne-like. The K- and L-shell radiations were captured using two time-gated and two axially resolved time-integrated spectrometers. The electron beam was measured using a Faraday cup. A multi-zone non-local thermodynamic equilibrium pinch model with radiation transport is used to model the x-ray emission from experiments for the purpose of obtaining plasma conditions. These plasma conditions are used to discuss some properties of the electron beam generated by runaway electrons. A simple model for runaway electrons is examined to produce the Kα radiation, but it is found to be insufficient.

  10. Inner-shell radiation from wire array implosions on the Zebra generator

    NASA Astrophysics Data System (ADS)

    Ouart, N. D.; Giuliani, J. L.; Dasgupta, A.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Shrestha, I.; Weller, M. E.; Shlyaptseva, V.; Osborne, G. C.; Stafford, A.; Keim, S.; Apruzese, J. P.; Clark, R. W.

    2014-03-01

    Implosions of brass wire arrays on Zebra have produced L-shell radiation as well as inner-shell Kα and Kβ transitions. The L-shell radiation comes from ionization stages around the Ne-like charge state that is largely populated by a thermal electron energy distribution function, while the K-shell photons are a result of high-energy electrons ionizing or exciting an inner-shell (1s) electron from ionization stages around Ne-like. The K- and L-shell radiations were captured using two time-gated and two axially resolved time-integrated spectrometers. The electron beam was measured using a Faraday cup. A multi-zone non-local thermodynamic equilibrium pinch model with radiation transport is used to model the x-ray emission from experiments for the purpose of obtaining plasma conditions. These plasma conditions are used to discuss some properties of the electron beam generated by runaway electrons. A simple model for runaway electrons is examined to produce the Kα radiation, but it is found to be insufficient.

  11. Application of 2-D simulations to hollow Z-pinch implosions

    SciTech Connect

    Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Lund, C.; Matuska, W.; McLenithan, K.; Oona, H.; Deeney, C.; Derzon, M.; Spielman, R. B.; Nash, T. J.; Chandler, G.; Mock, R. C.; Sanford, T. W. L.; Matzen, M. K.; Roderick, N. F.

    1997-05-05

    The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy (1,2,3). This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters (such as the resistivity) are required (1). Limitations in the use of this approach include the use of the 3-T, gray diffusion treatment of radiation and the fact that the initial perturbation conditions are not known a priori. Nonetheless, the approach has been successful in reproducing important experimental features of such implosions over a wide variety of timescales (tens of nanoseconds to microseconds), current drives (3 to 16 MA), masses (submilligram to tens of milligrams), initial radii (<1 cm to 5 cm), materials (Al and W) and initial configurations (thin foils and wire arrays with 40 to 240 wires). Currently we are applying this capability to the analysis of recent Saturn and PBFA-Z experiments (4,5). The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has

  12. Application of 2-D simulations to hollow Z-pinch implosions

    SciTech Connect

    Peterson, D.L.; Bowers, R.L.; Brownell, J.H.; Lund, C.; Matuska, W.; McLenithan, K.; Oona, H.; Deeney, C.; Derzon, M.; Spielman, R.B.; Nash, T.J.; Chandler, G.; Mock, R.C.; Sanford, T.W.; Matzen, M.K.; Roderick, N.F.

    1997-05-01

    The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy (1,2,3). This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters (such as the resistivity) are required (1). Limitations in the use of this approach include the use of the 3-T, gray diffusion treatment of radiation and the fact that the initial perturbation conditions are not known {ital a priori}. Nonetheless, the approach has been successful in reproducing important experimental features of such implosions over a wide variety of timescales (tens of nanoseconds to microseconds), current drives (3 to 16 MA), masses (submilligram to tens of milligrams), initial radii ({lt}1cm to 5 cm), materials (Al and W) and initial configurations (thin foils and wire arrays with 40 to 240 wires). Currently we are applying this capability to the analysis of recent Saturn and PBFA-Z experiments (4,5). The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D

  13. Balance of RNA sequence requirement and NS3/NS3a expression of segment 10 of orbiviruses.

    PubMed

    Feenstra, Femke; van Gennip, René G P; Schreuder, Myrte; van Rijn, Piet A

    2016-02-01

    Orbiviruses are insect-transmitted, non-enveloped viruses with a ten-segmented dsRNA genome of which the bluetongue virus (BTV) is the prototype. Viral non-structural protein NS3/NS3a is encoded by genome segment 10 (Seg-10), and is involved in different virus release mechanisms. This protein induces specific release via membrane disruptions and budding in both insect and mammalian cells, but also the cytopathogenic release that is only seen in mammalian cells. NS3/NS3a is not essential for virus replication in vitro with BTV Seg-10 containing RNA elements essential for virus replication, even if protein is not expressed. Recently, new BTV serotypes with distinct NS3/NS3a sequence and cell tropism have been identified. Multiple studies have hinted at the importance of Seg-10 in orbivirus replication, but the exact prerequisites are still unknown. Here, more insight is obtained with regard to the needs for orbivirus Seg-10 and the balance between protein expression and RNA elements. Multiple silent mutations in the BTV NS3a ORF destabilized Seg-10, resulting in deletions and sequences originating from other viral segments being inserted, indicating strong selection at the level of RNA during replication in mammalian cells in vitro. The NS3a ORFs of other orbiviruses were successfully exchanged in BTV1 Seg-10, resulting in viable chimeric viruses. NS3/NS3a proteins in these chimeric viruses were generally functional in mammalian cells, but not in insect cells. NS3/NS3a of the novel BTV serotypes 25 and 26 affected virus release from Culicoides cells, which might be one of the reasons for their distinct cell tropism. PMID:26644214

  14. PHELIX: design of transformer-driven linear implosion system

    SciTech Connect

    Turchi, Peter J; Atchison, Walter L; Rousculp, Chris L; Reinovsky, Robert E

    2008-01-01

    Experiments involving electromagnetically-imploded, solid-density liners can be achieved at reduced cost and energy if we start with a scale-size based on diagnostic resolution, rather than on the largest capacitor bank or generator we could bring to bear. For minimum resolution of 100 microns or less, many useful experiments could be performed with initial liner diameters that are factors of two to three smaller than used on high-energy systems, such as Atlas, thereby reducing energy requirements to sub-megajoule levels. Reduction in scale-size, however, also decreases the inductance change associated with liner motion relative to other inductances in the circuit. To improve coupling efficiency to liner kinetic energy, we invoke a current step-up transformer. Scaling relations have been developed for reducing the size and energy of such systems and compared with detailed numerical simulations. We discuss these calculations and describe the engineering embodiment of the resulting design for a system called PHELIX (Precision High Energy-density Liner Implosion eXperiment).

  15. Implosive Interatomic Coulombic decay in the simplest molecular anion

    NASA Astrophysics Data System (ADS)

    Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila

    2016-05-01

    Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.

  16. On the onset of kinetic effects in ICF implosions

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Bellei, Claudio; Wilks, Scott; Li, Chikang; Rinderknecht, Hans; Rosenberg, Michael; Sio, Hong; Petrasso, Richard

    2013-10-01

    Central hot spot ignition requires the careful sequencing of several shocks that coalesce in the gaseous deuterium-tritium fuel to form a high Mach number shock. Near the instant of shock convergence at the origin (or ``shock flash''), the ion mean free path may be a significant fraction of the hot spot radius, leading to a potential violation of the fluid approximation that generally underlies mainline radiation-hydrodynamic simulation tools. Understanding this physical regime may have consequences on subsequent hot spot formation and ignition performance margins. Recent data obtained on the Omega laser facility point to a transition in direct-drive exploding pusher implosion behavior below a threshold pressure where the ion mean free path is on the order of the fuel radius at shock flash. Adaptation of a Guderley-type shock solution in a converging geometry to include finite mean-free-path effects is undertaken to understand this kinetic regime. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and supported by LDRD-11-ERD-075 (LLNL) and NLUF/DOE DE-NA0002035 (MIT).

  17. Synergistic Activity of Combined NS5A Inhibitors.

    PubMed

    O'Boyle, Donald R; Nower, Peter T; Gao, Min; Fridell, Robert; Wang, Chunfu; Hewawasam, Piyasena; Lopez, Omar; Tu, Yong; Meanwell, Nicholas A; Belema, Makonen; Roberts, Susan B; Cockett, Mark; Sun, Jin-Hua

    2015-01-01

    Daclatasvir (DCV) is a first-in-class hepatitis C virus (HCV) nonstructural 5A replication complex inhibitor (NS5A RCI) that is clinically effective in interferon-free combinations with direct-acting antivirals (DAAs) targeting alternate HCV proteins. Recently, we reported NS5A RCI combinations that enhance HCV inhibitory potential in vitro, defining a new class of HCV inhibitors termed NS5A synergists (J. Sun, D. R. O'Boyle II, R. A. Fridell, D. R. Langley, C. Wang, S. Roberts, P. Nower, B. M. Johnson F. Moulin, M. J. Nophsker, Y. Wang, M. Liu, K. Rigat, Y. Tu, P. Hewawasam, J. Kadow, N. A. Meanwell, M. Cockett, J. A. Lemm, M. Kramer, M. Belema, and M. Gao, Nature 527:245-248, 2015, doi:10.1038/nature15711). To extend the characterization of NS5A synergists, we tested new combinations of DCV and NS5A synergists against genotype (gt) 1 to 6 replicons and gt 1a, 2a, and 3a viruses. The kinetics of inhibition in HCV-infected cells treated with DCV, an NS5A synergist (NS5A-Syn), or a combination of DCV and NS5A-Syn were distinctive. Similar to activity observed clinically, DCV caused a multilog drop in HCV, followed by rebound due to the emergence of resistance. DCV-NS5A-Syn combinations were highly efficient at clearing cells of viruses, in line with the trend seen in replicon studies. The retreatment of resistant viruses that emerged using DCV monotherapy with DCV-NS5A-Syn resulted in a multilog drop and rebound in HCV similar to the initial decline and rebound observed with DCV alone on wild-type (WT) virus. A triple combination of DCV, NS5A-Syn, and a DAA targeting the NS3 or NS5B protein cleared the cells of viruses that are highly resistant to DCV. Our data support the observation that the cooperative interaction of DCV and NS5A-Syn potentiates both the genotype coverage and resistance barrier of DCV, offering an additional DAA option for combination therapy and tools for explorations of NS5A function. PMID:26711745

  18. The interaction between the Hepatitis C proteins NS4B and NS5A is involved in viral replication

    PubMed Central

    David, Naama; Yaffe, Yakey; Hagoel, Lior; Elazar, Menashe; Glenn, Jeffrey S.; Hirschberg, Koret; Sklan, Ella H.

    2015-01-01

    Hepatitis C virus (HCV) replicates in membrane associated, highly ordered replication complexes (RCs). These complexes include viral and host proteins necessary for viral RNA genome replication. The interaction network among viral and host proteins underlying the formation of these RCs is yet to be thoroughly characterized. Here, we investigated the association between NS4B and NS5A, two critical RC components. We characterized the interaction between these proteins using fluorescence resonance energy transfer and a mammalian two-hybrid system. Specific tryptophan residues within the C-terminal domain (CTD) of NS4B were shown to mediate this interaction. Domain I of NS5A, was sufficient to mediate its interaction with NS4B. Mutations in the NS4B CTD tryptophan residues abolished viral replication. Moreover, one of these mutations also affected NS5A hyperphosphorylation. These findings provide new insights into the importance of the NS4B–NS5A interaction and serve as a starting point for studying the complex interactions between the replicase subunits. PMID:25462354

  19. Characterisation of divergent flavivirus NS3 and NS5 protein sequences detected in Rhipicephalus microplus ticks from Brazil

    PubMed Central

    Maruyama, Sandra Regina; Castro-Jorge, Luiza Antunes; Ribeiro, José Marcos Chaves; Gardinassi, Luiz Gustavo; Garcia, Gustavo Rocha; Brandão, Lucinda Giampietro; Rodrigues, Aline Rezende; Okada, Marcos Ituo; Abrão, Emiliana Pereira; Ferreira, Beatriz Rossetti; da Fonseca, Benedito Antonio Lopes; de Miranda-Santos, Isabel Kinney Ferreira

    2013-01-01

    Transcripts similar to those that encode the nonstructural (NS) proteins NS3 and NS5 from flaviviruses were found in a salivary gland (SG) complementary DNA (cDNA) library from the cattle tick Rhipicephalus microplus. Tick extracts were cultured with cells to enable the isolation of viruses capable of replicating in cultured invertebrate and vertebrate cells. Deep sequencing of the viral RNA isolated from culture supernatants provided the complete coding sequences for the NS3 and NS5 proteins and their molecular characterisation confirmed similarity with the NS3 and NS5 sequences from other flaviviruses. Despite this similarity, phylogenetic analyses revealed that this potentially novel virus may be a highly divergent member of the genus Flavivirus. Interestingly, we detected the divergent NS3 and NS5 sequences in ticks collected from several dairy farms widely distributed throughout three regions of Brazil. This is the first report of flavivirus-like transcripts in R. microplus ticks. This novel virus is a potential arbovirus because it replicated in arthropod and mammalian cells; furthermore, it was detected in a cDNA library from tick SGs and therefore may be present in tick saliva. It is important to determine whether and by what means this potential virus is transmissible and to monitor the virus as a potential emerging tick-borne zoonotic pathogen. PMID:24626302

  20. Glycosylation-related genes in NS0 cells are insensitive to moderately elevated ammonium concentrations

    PubMed Central

    Brodsky, Arthur Nathan; Caldwell, Mary; Bae, Sooneon; Harcum, Sarah W.

    2014-01-01

    NS0 and Chinese hamster ovary (CHO) cell lines are used to produce recombinant proteins for human therapeutics; however, ammonium accumulation can negatively impact cell growth, recombinant protein production, and protein glycosylation. To improve product quality and decrease costs, the relationship between ammonium and protein glycosylation needs to be elucidated. While ammonium has been shown to adversely affect glycosylation-related gene expression in CHO cells, NS0 studies have not been performed. Therefore, this study sought to determine if glycosylation in NS0 cells were ammonium-sensitive at the gene expression level. Using a DNA microarray that contained mouse glycosylation-related and housekeeping genes, the of these genes was analysed in response to various culture conditions – elevated ammonium, elevated salt, and elevated ammonium with proline. Surprisingly, no significant differences in gene expression levels were observed between the control and these conditions. Further, the elevated ammonium cultures were analysed using real-time quantitative reverse transcriptase PCR (qRT-PCR) for key glycosylation genes, and the qRT-PCR results corroborated the DNA microarray results, demonstrating that NS0 cells are ammonium-insensitive at the gene expression level. Since NS0 are known to have elevated nucleotide sugar pools under ammonium stress, and none of the genes directly responsible for these metabolic pools were changed, consequently cellular control at the translational or substrate-level must be responsible for the universally observed decreased glycosylation quality under elevated ammonium. PMID:25062658

  1. A Two Step Plasma Conditioning Scheme for High Current Plasma Implosions

    NASA Astrophysics Data System (ADS)

    Choi, P.; Zakharov, S. V.

    2006-01-01

    We consider the effect of using a limited energy current pre-pulse to first heat and evaporate a solid material in wire or cylindrical foil geometry, and second to allow the material to expand until a suitable characteristic scale dimension, like the skin depth, before the application of the main high current pulse for compression and heating. In this way, due to the large-scale density distribution formed during plasma expansion in the preparation phase, the short-wavelength instabilities may be suppressed. This idea is confirmed by 2-D RMHD simulations of the implosion of plasma from exploding a 13.6μm diameter tungsten wire evaporated with a low-energy pre-pulse, free expansion of the wire plasma until a necessary radius and subsequent implosion by a main pulse. The higher resistance against short-wavelength instabilities results in a better quality compression and a higher energy density plasma structure. For implosion of a thin foil liner, the idea of two step implosion is considered by comparison of 2-D RMHD simulations of the implosion of a 1.5μm copper foil at 18MA current amplitude in two cases: with and without pre-pulse. The fastest short-wavelength RT modes associated with high aspect ratio are suppressed due to a finite density gradient at the main pulse. The criteria for the optimum pre-pulse are examined to improve the radiation characteristics for given pulsed power conditions.

  2. Effects of electron-ion temperature equilibration on inertial confinement fusion implosions.

    PubMed

    Xu, Barry; Hu, S X

    2011-07-01

    The electron-ion temperature relaxation essentially affects both the laser absorption in coronal plasmas and the hot-spot formation in inertial confinement fusion (ICF). It has recently been reexamined for plasma conditions closely relevant to ICF implosions using either classical molecular-dynamics simulations or analytical methods. To explore the electron-ion temperature equilibration effects on ICF implosion performance, we have examined two Coulomb logarithm models by implementing them into our hydrocodes, and we have carried out hydrosimulations for ICF implosions. Compared to the Lee-More model that is currently used in our standard hydrocodes, the two models predict substantial differences in laser absorption, coronal temperatures, and neutron yields for ICF implosions at the OMEGA Laser Facility [Boehly et al. Opt. Commun. 133, 495 (1997)]. Such effects on the triple-picket direct-drive design at the National Ignition Facility (NIF) have also been explored. Based on the validity of the two models, we have proposed a combined model of the electron-ion temperature-relaxation rate for the overall ICF plasma conditions. The hydrosimulations using the combined model for OMEGA implosions have shown ∼6% more laser absorption, ∼6%-15% higher coronal temperatures, and ∼10% more neutron yield, when compared to the Lee-More model prediction. It is also noticed that the gain for the NIF direct-drive design can be varied by ∼10% among the different electron-ion temperature-relaxation models. PMID:21867323

  3. Performance of indirectly driven capsule implosions on the National Ignition Facility using adiabat-shaping

    NASA Astrophysics Data System (ADS)

    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 and fuel adiabat, separately and controllably. Three principal conclusions are drawn from this study: (1) It is shown that reducing ablation-front instability growth in low-foot implosions results in a substantial (3-10X) increase in neutron yield with no loss of fuel compression. (2) It is shown that reducing the fuel adiabat in high-foot implosions results in a significant (36%) increase in fuel compression together with a small (10%) increase in neutron yield. (3) Increased electron preheat at higher laser power in high-foot implosions, however, appears to offset the gain in compression achieved by adiabat-shaping at lower power. These results taken collectively bridge the space between the higher compression low-foot results and the higher yield high-foot results.

  4. Effects of local defect growth in direct-drive cryogenic implosions on OMEGA

    SciTech Connect

    Igumenshchev, I. V.; Shmayda, W. T.; Harding, D. R.; Sangster, T. C.; Goncharov, V. N.; Meyerhofer, D. D.

    2013-08-15

    Spherically symmetric, low-adiabat (adiabat α ≲ 3) cryogenic direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1995)] yield less than 10% of the neutrons predicted in one-dimensional hydrodynamic simulations. Two-dimensional hydrodynamic simulations suggest that this performance degradation can be explained assuming perturbations from isolated defects of submicron to tens-of-micron scale on the outer surface or inside the shell of implosion targets. These defects develop during the cryogenic filling process and typically number from several tens up to hundreds for each target covering from about 0.2% to 1% of its surface. The simulations predict that such defects can significantly perturb the implosion and result in the injection of about 1 to 2 μg of the hot ablator (carbon-deuterium) and fuel (deuterium-tritium) materials from the ablation surface into the targets. Both the hot mass injection and perturbations of the shell reduce the final shell convergence ratio and implosion performance. The injected carbon ions radiatively cool the hot spot, reducing the fuel temperature, and further reducing the neutron yield. The negative effect of local defects can be minimized by decreasing the number and size of these defects and/or using more hydrodynamically stable implosion designs with higher shell adiabat.

  5. Higher velocity, high-foot implosions on the National Ignition Facility lasera)

    NASA Astrophysics Data System (ADS)

    Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Döppner, T.; Ma, T.; Park, H.-S.; Barrios Garcia, M. A.; Berzak Hopkins, L. F.; Casey, D. T.; Cerjan, C. J.; Dewald, E. L.; Dittrich, T. R.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Kline, J. L.; Knauer, J. P.; Kritcher, A. L.; Landen, O. L.; LePape, S.; MacPhee, A. G.; Milovich, J. L.; Nikroo, A.; Pak, A. E.; Patel, P. K.; Rygg, J. R.; Ralph, J. E.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Benedetti, L. R.; Bionta, R. M.; Bond, E. J.; Bradley, D. K.; Caggiano, J. A.; Field, J. E.; Fittinghoff, D. N.; Frenje, J.; Gatu Johnson, M.; Grim, G. P.; Hatarik, R.; Merrill, F. E.; Nagel, S. R.; Izumi, N.; Khan, S. F.; Town, R. P. J.; Sayre, D. B.; Volegov, P.; Wilde, C. H.

    2015-05-01

    By increasing the velocity in "high foot" implosions [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014); Hurricane et al., Nature 506, 343 (2014); Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility laser, we have nearly doubled the neutron yield and the hotspot pressure as compared to the implosions reported upon last year. The implosion velocity has been increased using a combination of the laser (higher power and energy), the hohlraum (depleted uranium wall material with higher opacity and lower specific heat than gold hohlraums), and the capsule (thinner capsules with less mass). We find that the neutron yield from these experiments scales systematically with a velocity-like parameter of the square root of the laser energy divided by the ablator mass. By connecting this parameter with the inferred implosion velocity ( v ), we find that for shots with primary yield >1 × 1015 neutrons, the total yield ˜ v 9.4 . This increase is considerably faster than the expected dependence for implosions without alpha heating (˜ v 5.9 ) and is additional evidence that these experiments have significant alpha heating.

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

    PubMed

    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

  7. Higher velocity, high-foot implosions on the National Ignition Facility laser

    SciTech Connect

    Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Döppner, T.; Ma, T.; Park, H.-S.; Barrios Garcia, M. A.; Berzak Hopkins, L. F.; Casey, D. T.; Cerjan, C. J.; Dewald, E. L.; Dittrich, T. R.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Kritcher, A. L.; Landen, O. L.; LePape, S.; MacPhee, A. G.; Milovich, J. L.; and others

    2015-05-15

    By increasing the velocity in “high foot” implosions [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014); Hurricane et al., Nature 506, 343 (2014); Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility laser, we have nearly doubled the neutron yield and the hotspot pressure as compared to the implosions reported upon last year. The implosion velocity has been increased using a combination of the laser (higher power and energy), the hohlraum (depleted uranium wall material with higher opacity and lower specific heat than gold hohlraums), and the capsule (thinner capsules with less mass). We find that the neutron yield from these experiments scales systematically with a velocity-like parameter of the square root of the laser energy divided by the ablator mass. By connecting this parameter with the inferred implosion velocity (v), we find that for shots with primary yield >1 × 10{sup 15} neutrons, the total yield ∼ v{sup 9.4}. This increase is considerably faster than the expected dependence for implosions without alpha heating (∼v{sup 5.9}) and is additional evidence that these experiments have significant alpha heating.

  8. Higher velocity, high-foot implosions on the National Ignition Facility laser

    SciTech Connect

    Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Döppner, T.; Ma, T.; Park, H. -S.; Barrios Garcia, M. A.; Berzak Hopkins, L. F.; Casey, D. T.; Cerjan, C. J.; Dewald, E. L.; Dittrich, T. R.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Kline, J. L.; Knauer, J. P.; Kritcher, A. L.; Landen, O. L.; LePape, S.; MacPhee, A. G.; Milovich, J. L.; Nikroo, A.; Pak, A. E.; Patel, P. K.; Rygg, J. R.; Ralph, J. E.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Benedetti, L. R.; Bionta, R. M.; Bond, E. J.; Bradley, D. K.; Caggiano, J. A.; Field, J. E.; Fittinghoff, D. N.; Frenje, J.; Gatu Johnson, M.; Grim, G. P.; Hatarik, R.; Merrill, F. E.; Nagel, S. R.; Izumi, N.; Khan, S. F.; Town, R. P. J.; Sayre, D. B.; Volegov, P.; Wilde, C. H.

    2015-05-15

    By increasing the velocity in “high foot” implosions [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014); Hurricane et al., Nature 506, 343 (2014); Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility laser, we have nearly doubled the neutron yield and the hotspot pressure as compared to the implosions reported upon last year. The implosion velocity has been increased using a combination of the laser (higher power and energy), the hohlraum (depleted uranium wall material with higher opacity and lower specific heat than gold hohlraums), and the capsule (thinner capsules with less mass). We find that the neutron yield from these experiments scales systematically with a velocity-like parameter of the square root of the laser energy divided by the ablator mass. By connecting this parameter with the inferred implosion velocity (v), we find that for shots with primary yield >1e15 neutrons, the total yield ~ v⁹˙⁴. This increase is considerably faster than the expected dependence for implosions without alpha heating ( ~v⁵˙⁹) and is additional evidence that these experiments have significant alpha heating.

  9. Higher velocity, high-foot implosions on the National Ignition Facility laser

    DOE PAGESBeta

    Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Döppner, T.; Ma, T.; Park, H. -S.; Barrios Garcia, M. A.; Berzak Hopkins, L. F.; Casey, D. T.; Cerjan, C. J.; et al

    2015-05-15

    By increasing the velocity in “high foot” implosions [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014); Hurricane et al., Nature 506, 343 (2014); Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility laser, we have nearly doubled the neutron yield and the hotspot pressure as compared to the implosions reported upon last year. The implosion velocity has been increased using a combination of the laser (higher power and energy), the hohlraum (depleted uranium wall material with higher opacity and lower specific heat than gold hohlraums), andmore » the capsule (thinner capsules with less mass). We find that the neutron yield from these experiments scales systematically with a velocity-like parameter of the square root of the laser energy divided by the ablator mass. By connecting this parameter with the inferred implosion velocity (v), we find that for shots with primary yield >1e15 neutrons, the total yield ~ v⁹˙⁴. This increase is considerably faster than the expected dependence for implosions without alpha heating ( ~v⁵˙⁹) and is additional evidence that these experiments have significant alpha heating.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Mitigating laser imprint in direct-drive inertial confinement fusion implosions with high-Z dopants.

    PubMed

    Hu, S X; Fiksel, G; Goncharov, V N; Skupsky, S; Meyerhofer, D D; Smalyuk, V A

    2012-05-11

    Nonuniformities seeded by both long- and short-wavelength laser perturbations can grow via Rayleigh-Taylor (RT) instability in direct-drive inertial confinement fusion, leading to performance reduction in low-adiabat implosions. To mitigate the effect of laser imprinting on target performance, spherical RT experiments have been performed on OMEGA using Si- or Ge-doped plastic targets in a cone-in-shell configuration. Compared to a pure plastic target, radiation preheating from these high-Z dopants (Si/Ge) increases the ablation velocity and the standoff distance between the ablation front and laser-deposition region, thereby reducing both the imprinting efficiency and the RT growth rate. Experiments showed a factor of 2-3 reduction in the laser-imprinting efficiency and a reduced RT growth rate, leading to significant (3-5 times) reduction in the σ(rms) of shell ρR modulation for Si- or Ge-doped targets. These features are reproduced by radiation-hydrodynamics simulations using the two-dimensional hydrocode DRACO. PMID:23003051

  12. Magnetic pressure driven implosion of solid liner suitable for compression of field reverse configurations

    SciTech Connect

    Degnan, J.H.; Bartlett, R.; Cavazos, T.

    1999-07-01

    The initial design and performance of a magnetic pressure driven imploding solid liner with dimensions suitable for compressing a Field Reversed Configuration (FRC) is presented and discussed. The nominal liner parameters are 30 cm length, 5 cm outer radius, {approximately}0.1 cm thickness, Al material. The liner is imploded by magnetic pressure from an axial discharge driven by a 1,300 microfarad capacitor bank. Other nominal discharge parameters are {approximately}80 kV initial bank voltage, {approximately}44 nanohenry initial total inductance, and {approximately} milliohm series resistance. The discharge current exceeds 10 mega-amps in {approximately} 9 {micro}sec. Several types of calculations indicate that such a liner will implode in {approximately} 22 to 25 /{micro}sec, and will achieve a >0.3 cm/{micro}sec implosion velocity by the time the liner has imploded to {approximately}2.5 cm radius. This performance and these dimensions are suitable for FRC formation and compression, as discussed by K Schoenberg, R. Siemon, et al. (1). The diagnostics for the initial experiments include current (via Rogowski coils and inductive magnetic probes), voltage (via capacitive divider probes), flash radiography, and diagnostic magnetic field compression. Several types of simulations, including two dimensional magnetohydrodynamic simulations, are also discussed.

  13. Hydrodynamic Instability Growth Measurements at the Ablator-Fuel Interface in Layered ICF Capsule Implosions

    NASA Astrophysics Data System (ADS)

    Doeppner, Tilo; Weber, Chris; Casey, Dan; Bunn, Tom; Carlson, Lane; Dylla-Spears, Rebecca; Kozioziemski, Bernie; Macphee, Andy; Sater, Jim; Robey, Harry; Smalyuk, Vladimir

    2015-11-01

    Based on the well-established Hydro-growth Radiography (HGR) concept we have successfully developed and fielded a new target platform to measure instability growth at the ablator-fuel interface in layered capsule implosions on the NIF. We present the results of a proof-of-principle experiment for which mode 60 perturbations with an amplitude of 4.4 μm peak-to-valley were laser-machined at the inside of a 0.8-scale plastic ablator capsule. A 55 μm thick, polycrystalline DT ice layer was grown on top of these perturbations. High quality radiography data were recorded at 4 times, showing the growth of these perturbations in both the linear and non-linear stage. We find good agreement with preliminary HYDRA simulations that include small-scale perturbations introduced by the laser machining. Future directions will be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE- AC52-07NA27344.

  14. Code Validation Utilizing Spectral Data Analysis of ICF Implosion Experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Gunderson, Mark; Haynes, Donald, Jr.; Delamater, Norman; Regan, Sean

    2003-10-01

    Time-resolved spectral data from recent ICF implosion experiments of plastic microballoons containing deuterium fuel doped with argon is proving quite useful in checking the corresponding 1D and 2D simulation results from the multi-dimensional hydrocode RAGE [1]. Comparisons with experimental density and temperature determined by fitting theoretical argon line shapes generated by MERL [2] to experimental data show that the simulated density and temperature in the fuel are too large unless some seed for mixing is incorporated. We use a nonuniform drive as a seed for mix. The need for mix is further supported through simulations using the 1D Lagrangian code HYADES (no mix) that give neutron yields an order of magnitude larger than that seen in experiment. This work was performed under NLUF grant DE-FG03-01SF22224 and DOE contract No. W-7405-ENG-36. [1] Gittings, M.L., SAIC's adaptive grid Eulerian hydrocode, DNA Numerical Methods Symposium, Apr 1992. [2] Mancini, R.C., Kilcrease, D.P., Woltz, L.A., and Hooper Jr., C.F., Comput. Phy. Commun. 63, 314-322 (1991).

  15. Application of 2-D simulations to hollow z-pinch implosions

    SciTech Connect

    Peterson, D.L.; Bowers, R.L.; Brownell, J.H.

    1997-12-01

    The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus 1 and Pegasus 2 capacitor banks, the authors have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy. This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters are required. Currently the authors are applying this capability to the analysis of recent Saturn and PBFA-Z experiments. The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has also been applied to the analysis of Saturn dynamic hohlraum experiments and is being used in the design of this and other Z-Pinch applications on PBFA-Z.

  16. Hepatitis C Virus NS3 Inhibitors: Current and Future Perspectives

    PubMed Central

    Akimitsu, Nobuyoshi

    2013-01-01

    Currently, hepatitis C virus (HCV) infection is considered a serious health-care problem all over the world. A good number of direct-acting antivirals (DAAs) against HCV infection are in clinical progress including NS3-4A protease inhibitors, RNA-dependent RNA polymerase inhibitors, and NS5A inhibitors as well as host targeted inhibitors. Two NS3-4A protease inhibitors (telaprevir and boceprevir) have been recently approved for the treatment of hepatitis C in combination with standard of care (pegylated interferon plus ribavirin). The new therapy has significantly improved sustained virologic response (SVR); however, the adverse effects associated with this therapy are still the main concern. In addition to the emergence of viral resistance, other targets must be continually developed. One such underdeveloped target is the helicase portion of the HCV NS3 protein. This review article summarizes our current understanding of HCV treatment, particularly with those of NS3 inhibitors. PMID:24282816

  17. Ideal and non-ideal MHD regimes of wire array implosion obtained in 3D hybrid simulations and observed during experiments at NTF.

    SciTech Connect

    Sotnikov, Vladimir Isaakovich; Fiala, V.; Oliver, Bryan Velten; Ivanov, Vladimir V.; LePell, Paul David; Fedin, Dmitry; Mehlhorn, Thomas Alan; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Travnicek, P.; Hellinger, P.; Deeney, Christopher; Jones, Brent Manley; Safronova, Alla S.; Leboeuf, J. N.; Cowan, Thomas E.

    2004-11-01

    Recent 3D hybrid simulation of a plasma current-carrying column revealed two regimes of sausage and kink instability development. In the first regime, with small Hall parameter, development of instabilities leads to appearance of large-scale axial perturbations and eventually to the bending of the plasma column. In the second regime, with five times larger Hall parameter, small-scale perturbations dominated and no bending of the plasma column was observed. Simulation results are compared to recent experimental data, including laser probing, x-ray spectroscopy and time-gated x-ray imaging during wire array implosions at NTF.

  18. Ultrastructure of Kunjin virus-infected cells: colocalization of NS1 and NS3 with double-stranded RNA, and of NS2B with NS3, in virus-induced membrane structures.

    PubMed Central

    Westaway, E G; Mackenzie, J M; Kenney, M T; Jones, M K; Khromykh, A A

    1997-01-01

    The subcellular location of the nonstructural proteins NS1, NS2B, and NS3 in Vero cells infected with the flavivirus Kunjin was investigated using indirect immunofluorescence and cryoimmunoelectron microscopy with monospecific antibodies. Comparisons were also made by dual immunolabelling using antibodies to double-stranded RNA (dsRNA), the putative template in the flavivirus replication complex. At 8 h postinfection, the immunofluorescent patterns showed NS1, NS2B, NS3, and dsRNA located in a perinuclear rim with extensions into the peripheral cytoplasm. By 16 h, at the end of the latent period, all patterns had changed to some discrete perinuclear foci associated with a thick cytoplasmic reticulum. By 24 h, this localization in perinuclear foci was more apparent and some foci were dual labelled with antibodies to dsRNA. In immuno-gold-labelled cryosections of infected cells at 24 h, all antibodies were associated with clusters of induced membrane structures in the perinuclear region. Two important and novel observations were made. First, one set of induced membranes comprised vesicle packets of smooth membranes dual labelled with anti-dsRNA and anti-NS1 or anti-NS3 antibodies. Second, adjacent masses of paracrystalline arrays or of convoluted smooth membranes, which appeared to be structurally related, were strongly labelled only with anti-NS2B and anti-NS3 antibodies. Paired membranes similar in appearance to the rough endoplasmic reticulum were also labelled, but less strongly, with antibodies to the three nonstructural proteins. Other paired membranes adjacent to the structures discussed above enclosed accumulated virus particles but were not labelled with any of the four antibodies. The collection of induced membranes may represent virus factories in which translation, RNA synthesis, and virus assembly occur. PMID:9261387

  19. Effects of nanosecond pulsed electrical fields (nsPEFs) on the cell cycle of CHO and Jurkat cells

    NASA Astrophysics Data System (ADS)

    Mahlke, Megan A.; Navara, Christopher; Ibey, Bennett L.

    2014-03-01

    Exposure to nano-second pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. Variations between cell lines in membrane and cytoskeletal structure as well as in survival of nsPEF exposure should correspond to unique line-dependent cell cycle effects. Additionally, phase of cell cycle during exposure may be linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate role of cell cycle phase in survival of nsPEFs. CHO populations recovered similarly to sham populations postnsPEF exposure and did not exhibit a phase-specific change in response. Jurkat cells exhibited considerable apoptosis/necrosis in response to nsPEF exposure and were unable to recover and proliferate in a manner similar to sham exposed cells. Additionally, Jurkat cells appear to be more sensitive to nsPEFs in G2/M phases than in G1/S phases. Recovery of CHO populations suggests that nsPEFs do not inhibit proliferation in CHO cells; however, inhibition of Jurkat cells post-nsPEF exposure coupled with preferential cell death in G2/M phases suggest that cell cycle phase during exposure may be an important factor in determining nsPEF toxicity in certain cell lines. Interestingly, CHO cells have a more robust and rigid cytoskeleton than Jurkat cells which is thought to contribute to their ability to

  20. Cross-Beam Energy Transfer Mitigation in Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The OMEGA Laser System is used to study the physics of cryogenic implosions that are hydrodynamically equivalent to the spherical ignition designs of the National Ignition Facility. Based on these experiments, cross-beam energy transfer (CBET) has been identified as the main mechanism reducing laser coupling and hydroefficiency. To mitigate CBET, target size Rt was increased with respect to the size of the beam focal spot Rb. This increases drive pressure, allowing for a thicker, more-stable target to reach ignition-relevant implosion velocities. The beam shape was optimized to minimize the nonuniformity produced when Rb/Rt <1. This talk will summarize the latest results in direct-drive implosions with different Rb/Rt. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Understanding the Performance of Low-Adiabat Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    While the moderate-adiabat (α > 3.5) cryogenic implosions on OMEGA are well understood using multidimensional hydrocode simulations, the performance of lower-adiabat implosions is degraded relative to code predictions. The potential degradation mechanisms (not fully accounted for in simulations) include target-nonuniformity sources (excessive laser imprint, target debris, beam-overlap nonuniformity) and inaccuracies in laser-coupling modeling, especially during the pulse rise. To address the target-stability issues, target designs with thicker ice layers and smaller implosion velocities are considered. These targets have smaller in-flight aspect ratios, making them less susceptible to hydrodynamic instability growth. To address inaccuracies in laser coupling, a design with a slower main pulse rise is considered. This talk will summarize progress made on these issues. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  2. Asymmetric directly driven capsule implosions: Modeling and experiments--A requirement for the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Cobble, J. A.; Murphy, T. J.; Schmitt, M. J.; Bradley, P. A.; Krashenninikova, N. S.; Obrey, K. A.; Hsu, S. C.; Tregillis, I. L.; Magelssen, G. R.; Wysocki, F. J.; Batha, S. H.

    2012-12-01

    Direct-drive experiments at the University of Rochester's OMEGA laser [T. R. Boehly, R. L. McCrory, C. P. Verdon et al., Fusion Eng. Des. 44, 35 (1999)] have been performed to prototype eventual campaigns on the National Ignition Facility (NIF) [E. I. Moses and C. R. Wuest, Fusion Sci. Technol. 43, 420 (2003)] to investigate the mixing of target materials. Spherical-implosion targets with equatorial defects have been irradiated with polar direct drive, a requirement for direct-drive experiments at NIF. The physics question addressed by these results is whether simulations can match data on 0th-order hydrodynamics and implosion symmetry, the most basic implosion features, with and without the defect. The successful testing of hydrodynamic simulations leads to better designs for experiments and guides accurate planning for polar-direct-drive-ignition studies on the NIF platform.

  3. Laser-beam zooming to mitigate crossed-beam energy losses in direct-drive implosions.

    PubMed

    Igumenshchev, I V; Froula, D H; Edgell, D H; Goncharov, V N; Kessler, T J; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Sangster, T C; Seka, W; Skupsky, S

    2013-04-01

    Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by ∼ 30%-40% after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain ≫ 1. PMID:25166997

  4. Appraisal of UTIAS implosion-driven hypervelocity launchers and shock tubes.

    NASA Technical Reports Server (NTRS)

    Glass, I. I.

    1972-01-01

    A critical appraisal is made of the design, research, development, and operation of the novel UTIAS implosion-driven hypervelocity launchers and shock tubes. Explosively driven (PbN6-lead azide, PETN-pentaerythritetetranitrate) implosions in detonating stoichiometric hydrogen-oxygen mixtures have been successfully developed as drivers for hypervelocity launchers and shock tubes in a safe and reusable facility. Intense loadings at very high calculated pressures, densities, and temperatures, at the implosion center, cause severe problems with projectile integrity. Misalignment of the focal point can occur and add to the difficulty in using small caliber projectiles. In addition, the extreme driving conditions cause barrel expansion, erosion, and possible gas leakage from the base to the head of the projectile which cut the predicted muzzle velocities to half or a third of the lossless calculated values. However, in the case of a shock-tube operation these difficulties are minimized or eliminated and the possibilities of approaching Jovian reentry velocities are encouraging.

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

    NASA Astrophysics Data System (ADS)

    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 heat