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Sample records for hohlraums hlp1 hlp2

  1. Energy coupling in lined hohlraums (HLP1, HLP2, and HLP7)

    SciTech Connect

    Kauffman, R.L.; Suter, L.J.; Berger, R.L.

    1996-06-01

    Indirect-drive inertial confinement fusion (ICF) uses high-Z cavities, or hohlraums, to confine x rays for compressing and igniting deuterium-tritium fuel contained in spherical capsules. For laser-driven ICF, the intense laser beams enter the hohlraum through small laser entrance holes (LEHs), heating the high-Z hohlraum walls. The laser-produced radiation heats the unirradiated high-Z walls producing a nearly isotropic radiation environment for spherically compressing the lCF capsule. The radiation flux on the capsule is not completely isotropic, however, because the laser-irradiated area is generally brighter than the surrounding x-ray heated walls and the LEHs do not radiate. Furthermore, the angular distribution of flux on the capsule is time dependent because the unilluminated walls become hotter and more emissive as a function of time, and plasma dynamics cause the laser-irradiated area to move. Symmetric implosions are obtained by dynamically balancing the effects of the LEHs, wall heating, and laser-spot motion.

  2. Hohlraum Characterization Milestones

    SciTech Connect

    Gunther, J

    2004-11-12

    A successful ignition campaign will depend in part upon having highly characterized hohlraums and shells for target assemblies. Regarding holhraums, properties of interest include dimensions, surface features and chemical composition. This report outlines the metrology needs for hohlraums and provides a timeline for capital as well as FTE expenditures through '07. The topics discussed include hohlraum metrology, windows and tenting metrology, with comments on support of other areas including cryo-related development efforts. Although there is a strong interest in non-destructive characterization, this report also investigates the use of destructive techniques for providing critical information for process development and improvement.

  3. Uniformity in Tetrahedral Hohlraums

    NASA Astrophysics Data System (ADS)

    Craxton, R. S.; Schnittman, J. D.; Pollaine, S. M.

    1996-11-01

    Tetrahedral hohlraums, i.e., spherical hohlraums with four laser entrance holes (LEH's), offer an alternative means of obtaining good time-independent capsule irradiation uniformity. Since the laser spots are spread fairly uniformly over the hohlraum wall, time-dependent uniformity swings are minimized. Using the 3-D view-factor code BUTTERCUP we have found, for both OMEGA and the NIF, that the uniformity is typically ~2% rms at all times, mainly in the Y_32 mode, but can be reduced to ~1% by independently varying the power in each beam. We have investigated the sensitivity of tetrahedral hohlraums to errors in beam-energy balance and pointing, and we have examined how large the LEH's must be to allow the beams to go through without refraction or absorption. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460. *Also Lawrence Livermore National Laboratory.

  4. Simulation of Hohlraum Wall Texture for Improved Performance in Hohlraums

    SciTech Connect

    Meyer, Isaac Chartrand; Urbatsch, Todd James; Scott, John Mitchell

    2016-08-15

    The performance of hohlraums for use in NIF (National Ignition Facility) is explored using Cassio: a LANL produced radiation hydrodynamics code that implements implicit Monte Carlo radiation transport. We examine the effect on blowoff of adding texture to the inside of the hohlraum wall. These new designs are compared in simulation against current designs and the data are analyzed for the possible use of such hohlraums in future high energy density physics experiments.

  5. National Ignition Campaign Hohlraum Energetics

    SciTech Connect

    Meezan, N B; Atherton, L J; Callahan, D A; Dewald, E L; Dixit, S N; Dzenitis, E G; Edwards, M J; Haynam, C A; Hinkel, D E; Jones, O S; Landen, O; London, R A; Michel, P A; Moody, J D; Milovich, J L; Schneider, M B; Thomas, C A; Town, R J; Warrick, A L; Weber, S V; Widmann, K; Glenzer, S H; Suter, L J; MacGowan, B J; Kline, J L; Kyrala, G A; Nikroo, A

    2009-11-16

    The first series of experiments on the National Ignition Facility (NIF) [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, and R. Al-Ayat, 'The National Ignition Facility: ushering in a new age for high energy density science,' Phys. Plasmas 16, 041006 (2009)] tested ignition hohlraum 'energetics,' a term described by four broad goals: (1) Measurement of laser absorption by the hohlraum; (2) Measurement of the x-ray radiation flux (T{sub RAD}{sup 4}) on the surrogate ignition capsule; (3) Quantitative understanding of the laser absorption and resultant x-ray flux; and (4) Determining whether initial hohlraum performance is consistent with requirements for ignition. This paper summarizes the status of NIF hohlraum energetics experiments. The hohlraum targets and experimental design are described, as well as the results of the initial experiments. The data demonstrate low backscattered energy (< 10%) for hohlraums filled with helium gas. A discussion of our current understanding of NIF hohlraum x-ray drive follows, including an overview of the computational tools, i.e., radiation-hydrodynamics codes, that have been used to design the hohlraums. The performance of the codes is compared to x-ray drive and capsule implosion data from the first NIF experiments. These results bode well for future NIF ignition hohlraum experiments.

  6. Study on Octahedral Spherical Hohlraum

    NASA Astrophysics Data System (ADS)

    Lan, Ke; Liu, Jie; Huo, Wenyi; Li, Zhichao; Yang, Dong; Li, Sanwei; Ren, Guoli; Chen, Yaohua; Jiang, Shaoen; He, Xian-Tu; Zhang, Weiyan

    2015-11-01

    In this talk, we report our recent study on octahedral spherical hohlraum which has six laser entrance holes (LEHs). First, our study shows that the octahedral hohlraums have robust high symmetry during the capsule implosion at hohlraum-to- capsule radius ratio larger than 3.7 and have potential superiority on low backscatter without supplementary technology. Second, we study the laser arrangement and constraints of the octahedral hohlraums and give their laser arrangement design for ignition facility. Third, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs, in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport. Fourth, we study the sensitivity of capsule symmetry inside the octahedral hohlraums to laser power balance, pointing accuracy, deviations from the optimal position and target fabrication accuracy, and compare the results with that of tradiational cylinders and rugby hohlraums. Finally, we present our recent experimental studies on the octahedral hohlraums on SGIII prototype laser facility.

  7. Fundamentals of ICF Hohlraums

    SciTech Connect

    Rosen, M D

    2005-09-30

    On the Nova Laser at LLNL, we demonstrated many of the key elements required for assuring that the next laser, the National Ignition Facility (NIF) will drive an Inertial Confinement Fusion (ICF) target to ignition. The indirect drive (sometimes referred to as ''radiation drive'') approach converts laser light to x-rays inside a gold cylinder, which then acts as an x-ray ''oven'' (called a hohlraum) to drive the fusion capsule in its center. On Nova we've demonstrated good understanding of the temperatures reached in hohlraums and of the ways to control the uniformity with which the x-rays drive the spherical fusion capsules. In these lectures we will be reviewing the physics of these laser heated hohlraums, recent attempts at optimizing their performance, and then return to the ICF problem in particular to discuss scaling of ICF gain with scale size, and to compare indirect vs. direct drive gains. In ICF, spherical capsules containing Deuterium and Tritium (DT)--the heavy isotopes of hydrogen--are imploded, creating conditions of high temperature and density similar to those in the cores of stars required for initiating the fusion reaction. When DT fuses an alpha particle (the nucleus of a helium atom) and a neutron are created releasing large amount amounts of energy. If the surrounding fuel is sufficiently dense, the alpha particles are stopped and can heat it, allowing a self-sustaining fusion burn to propagate radially outward and a high gain fusion micro-explosion ensues. To create those conditions the outer surface of the capsule is heated (either directly by a laser or indirectly by laser produced x-rays) to cause rapid ablation and outward expansion of the capsule material. A rocket-like reaction to that outward flowing heated material leads to an inward implosion of the remaining part of the capsule shell. The pressure generated on the outside of the capsule can reach nearly 100 megabar (100 million times atmospheric pressure [1b = 10{sup 6} cgs

  8. Hohlraum Simulations for Symergy Capsules

    NASA Astrophysics Data System (ADS)

    Goldman, S. R.; Hoffman, N. M.; Kyrala, G. A.; Wilson, D. C.

    2006-10-01

    The use of a single capsule implosion within a hohlraum to provide information on both the asymmetry of the radiation drive impinging on the capsule and the total energy absorbed by it has led to the concept of experiments with ``symergy'' capsules. We present simulations for planned shots at Omega with hohlraum drive approximating the first 6 ns of the actual NIF ignition drive and surrogate capsules for the NIF ignition capsule. The hohlraum modeling can assess the effects of hohlraum gas fill, laser timing variations and beam pointings. In addition to its immediate design use, it should be useful in validating both the predictive capability for observed symergy capsule responses and the modeling of the initial stage of the NIF ignition process. N.M. Hoffman, D. C. Wilson, and G. A. Kyrala, 2006 High-Temperature Diagnostics Conference, May 2006, Williamsburg, VA USA, to appear in Rev Sci Inst. 77 (2006)

  9. Reproducibility of NIF hohlraum measurements

    NASA Astrophysics Data System (ADS)

    Moody, J. D.; Ralph, J. E.; Turnbull, D. P.; Casey, D. T.; Albert, F.; Bachmann, B. L.; Doeppner, T.; Divol, L.; Grim, G. P.; Hoover, M.; Landen, O. L.; MacGowan, B. J.; Michel, P. A.; Moore, A. S.; Pino, J. E.; Schneider, M. B.; Tipton, R. E.; Smalyuk, V. A.; Strozzi, D. J.; Widmann, K.; Hohenberger, M.

    2015-11-01

    The strategy of experimentally ``tuning'' the implosion in a NIF hohlraum ignition target towards increasing hot-spot pressure, areal density of compressed fuel, and neutron yield relies on a level of experimental reproducibility. We examine the reproducibility of experimental measurements for a collection of 15 identical NIF hohlraum experiments. The measurements include incident laser power, backscattered optical power, x-ray measurements, hot-electron fraction and energy, and target characteristics. We use exact statistics to set 1-sigma confidence levels on the variations in each of the measurements. Of particular interest is the backscatter and laser-induced hot-spot locations on the hohlraum wall. Hohlraum implosion designs typically include variability specifications [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. We describe our findings and compare with the specifications. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  10. 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.

  11. Hohlraum manufacture for inertial confinement fusion

    SciTech Connect

    Foreman, L.R.; Gobby, P.; Bartos, J.

    1994-07-01

    Hohlraums are an integral part of indirect drive targets for Inertial Confinement Fusion (ICF) research. Hohlraums are made by an electroforming process that combines elements of micromachining and coating technology. The authors describe how these target element are made and extension of the method that allow fabrication of other, more complex target components.

  12. Wall-shaped hohlraum influence on symmetry and energetics in gas-filled hohlraums

    NASA Astrophysics Data System (ADS)

    Tassin, Veronique; Philippe, Franck; Laffite, Stephane; Videau, Laurent; Monteil, Marie-Christine; Villette, Bruno; Stemmler, Philippe; Bednarczyk, Sophie; Peche, Emilie; Reneaume, Benoit; Thessieux, Christian

    2008-11-01

    On the way to the LMJ completion, achieving ignition with 40 quads in a 2-cone configuration will be attempted as a first step. Theoretical investigation of a rugby-shaped hohlraum shows energetics optimization and a better symmetry control compared to a cylindrical hohlraum [1]. We recently conducted experiments on the Omega laser facility with 3 different wall-shaped methane-filled hohlraum configurations. We present here the experimental results. Energetics benefits are shown for reduced wall area hohlraums. The wall-shaped hohlraum influence on time-dependent radiation symmetry is also discussed. For the 3 gas-filled hohlraums configurations, we compare the foamball early-time radiographs, the D2Ar-filled capsule time-integrated images and the core self-emission images. [1] M. Vandenboomgaerde, Phys. Rev. Lett., 99, 065004 (2007).

  13. Laser Plasma Coupling for High Temperature Hohlraums

    SciTech Connect

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  14. Progress of Rugby Hohlraum Experiments on Omega

    NASA Astrophysics Data System (ADS)

    Philippe, Franck; Tassin, Veronique; Casner, Alexis; Gauthier, Pascal; Seytor, Patricia; Monteil, Marie-Christine; Park, Hye-Sook; Robey, Harry; Ross, Steven; Amendt, Peter; Girard, Frederic; Villette, Bruno; Reverdin, Charles; Loiseau, Pascal; Caillaud, Tony; Landoas, Olivier; Li, Chi Kang; Petrasso, Richard; Seguin, Fredrick; Rosenberg, Markus

    2011-10-01

    The rugby hohlraum concept is predicted to enable better coupling and higher gains in the indirect drive approach to ignition. A collaborative experimental program is currently pursued on OMEGA to test this concept in preparation for future megajoule-scale ignition designs. A direct comparison of gas-filled rugby hohlraums with classical cylinders was recently performed, showing a significant (up to ~40%) observed x-ray drive enhancement and neutron yields that are consistently higher in the rugby case. This work extends and confirms our previous findings in empty rugby hohlraums.

  15. Improving Hohlraums for High Foot Implosions

    NASA Astrophysics Data System (ADS)

    Hinkel, D. E.; Berzak Hopkins, L. F.; Ma, T.; Ralph, J. E.; Albert, F.; Benedetti, L. R.; Celliers, P. M.; Doeppner, T.; Goyon, C. S.; Izumi, N.; Jarrott, L. C.; Khan, S. F.; Kline, J. L.; Kritcher, A. L.; Kyrala, G. A.; Nagel, S. R.; Pak, A. E.; Patel, P.; Rosen, M. D.; Rygg, J. R.; Schneider, M. B.; Turnbull, D. P.; Yeamans, C. B.; Callahan, D. A.; Hurricane, O. A.

    2016-10-01

    Analysis of High Foot implosions show that performance has been limited by the radiation drive environment, i.e., the hohlraum. Demonstrated here is that improvements in the radiation environment result in an enhancement in implosion performance. This is accomplished by using a longer, larger case-to-capsule ratio hohlraum at lower gas fill density. At fixed laser energy, High Foot implosions driven with this hohlraum have achieved a 1.4 x increase in stagnation pressure, with an accompanying relative increase in fusion yield of 50%. Low mode asymmetries are still present, however, and are most likely a consequence of poor inner beam propagation through the hohlraum to the wall. Presented here are results from these High Foot implosions, as well as analyses of inner beam propagation, and additional hohlraum improvements that further ameliorate the implosion. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. State of Modeling Symmetry in Hohlraums

    SciTech Connect

    Jones, O. S.

    2015-07-22

    Modeling radiation drive asymmetry is challenging problem whose agreement with data depends on the hohlraum gas fill density. Modeling to date uses the HYDRA code with crossbeam energy transfer (CBET) calculated separately, and backscattered light removed from the input laser. For high fill hohlraums (~>1 mg/cc), matching symmetry requires ad hoc adjustments to CBET during picket and peak of drive. For near-vacuum hohlraums, there is little CBET or backscatter, and drive is more waist-high than predicted. For intermediate fill densities (~0.6 mg/cc) there appears to be a region of small CBET and backscatter where symmetry is reasonably well modeled. A new technique where backscatter and CBET are done “inline” appears it could bring high fill simulations closer to data.

  17. 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.

  18. Radiation Hydrodynamics Modeling of Hohlraum Energetics

    NASA Astrophysics Data System (ADS)

    Patel, Mehul V.; Mauche, Christopher W.; Jones, Ogden S.; Scott, Howard A.

    2015-11-01

    Attempts to model the energetics in NIF Hohlraums have been made with varying degrees of success, with discrepancies of 0-25% being reported for the X-ray flux (10-25% for the NIC ignition platform hohlraums). To better understand the cause(s) of these discrepancies, the effects of uncertainties in modeling thermal conduction, laser-plasma interactions, atomic mixing at interfaces, and NLTE kinetics of the high-Z wall plasma must be quantified. In this work we begin by focusing on the NLTE kinetics component. We detail a simulation framework for developing an integrated HYDRA hohlraum model with predefined tolerances for energetics errors due to numerical discretization errors or statistical fluctuations. Within this framework we obtain a model for a converged 1D spherical hohlraum which is then extended to 2D. The new model is used to reexamine physics sensitivities and improve estimates of the energetics discrepancy. Prepared by LLNL under Contract DE-AC52-07NA27344.

  19. Hohlraum design for the LMJ ignition target

    NASA Astrophysics Data System (ADS)

    Malinie, G.; Cherfils, C.; Gauthier, P.; Lambert, F.; Monteil, M. C.

    2011-10-01

    First experiments with the Laser MegaJoule (LMJ) are scheduled to be performed in 2014. The current nominal point design for ignition with 160 beams on the LMJ has been described in. It consists of an indirectly driven A943 capsule, with a plastic ablator doped with Germanium. This capsule is mounted in the center of a Rugby-shaped hohlraum, which is filled with a low density H/He gas, and has a gold-uranium cocktail wall lined with pure gold. We investigate the influence of two key parameters of the hohlraum design: the radius of the laser entrance holes (LEHs), and the thickness of the cocktail layer. Since the Rugby shape of the nominal point design is that of a half-ellipse going from the hohlraum waist to the LEH, any change in the LEH radius has a global effect on the hohlraum shape. Taking into account the current laser spot profiles of the LMJ and using 2D integrated calculations with our FCI2 radiation hydrodynamics code, we assess the flexiblility we have to reduce the LEH radius and/or the cocktail layer thickness.

  20. The physics of radiation driven ICF hohlraums

    SciTech Connect

    Rosen, M.D.

    1995-08-07

    On the Nova Laser at LLNL, we have recently demonstrated many of the key elements required for assuring that the next proposed laser, the National Ignition Facility (NIF) will drive an Inertial Confinement Fusion (ICF) target to ignition. The target uses the recently declassified indirect drive (sometimes referred to as {open_quotes}radiation drive{close_quotes}) approach which converts laser light to x-rays inside a gold cylinder, which then acts as an x-ray {open_quotes}oven{close_quotes} (called a hohlraum) to drive the fusion capsule in its center. On Nova we`ve demonstrated good understanding of the temperatures reached in hohlraums and of the ways to control the uniformity with which the x-rays drive the spherical fusion capsules. In this lecture we briefly review the fundamentals of ICF, and describe the capsule implosion symmetry advantages of the hohlraum approach. We then concentrate on a quantitative understanding of the scaling of radiation drive with hohlraum size and wall material, and with laser pulse length and power. We demonstrate that coupling efficiency of x-ray drive to the capsule increases as we proceed from Nova to the NIF and eventually to a reactor, thus increasing the gain of the system.

  1. Optimizing implosion yields using rugby-shaped hohlraums

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Robey, H.; Amendt, P.; Philippe, F.; Casner, A.; Caillaud, T.; Bourgade, J.-L.; Landoas, O.; Li, C. K.; Petrasso, R.; Seguin, F.; Rosenberg, M.; Glebov, V. Yu.

    2009-11-01

    We present the first experimental results on optimizing capsule implosion experiments by using rugby-shaped hohlraums [1] on the Omega laser, University of Rochester. This campaign compared D2-filled capsule performance between standard cylindrical Au hohlraums and rugby-shaped hohlraums for demonstrating the energetics advantages of the rugby geometry. Not only did the rugby-shaped hohlraums show nearly 20% more x-ray drive energy over the cylindrical hohlraums, but also the high-performance design of the capsules provided nearly 20 times more DD neutrons than in any previous Omega hohlraum campaigns, thereby enabling use of neutron temporal diagnostics. Comparison with simulations on neutron burn histories, x-ray core imaging, backscattered laser light and radiation temperature are presented. [1] P. Amendt et al., Phys. Plasmas 15, 012702 (2008)

  2. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    NASA Astrophysics Data System (ADS)

    Lan, Ke; Zheng, Wudi

    2014-09-01

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.

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

    SciTech Connect

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

    2005-06-17

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

  4. Status Update: Modeling Energy Balance in NIF Hohlraums

    SciTech Connect

    Jones, O. S.

    2015-07-22

    We have developed a standardized methodology to model hohlraum drive in NIF experiments. We compare simulation results to experiments by 1) comparing hohlraum xray fluxes and 2) comparing capsule metrics, such as bang times. Long-pulse, high gas-fill hohlraums require a 20-28% reduction in simulated drive and inclusion of ~15% backscatter to match experiment through (1) and (2). Short-pulse, low fill or near-vacuum hohlraums require a 10% reduction in simulated drive to match experiment through (2); no reduction through (1). Ongoing work focuses on physical model modifications to improve these matches.

  5. High Foot Implosion Experiments in Rugby Hohlraums

    NASA Astrophysics Data System (ADS)

    Ralph, Joseph; Leidinger, J.-P.; Callahan, D.; Kaiser, P.; Morice, O.; Marion, D.; Moody, J. D.; Ross, J. S.; Amendt, P.; Kritcher, A. L.; Milovich, J. L.; Strozzi, D.; Hinkel, D.; Michel, P.; Berzak Hopkins, L.; Pak, A.; Dewald, E. L.; Divol, L.; Khan, S.; Rygg, R.; Hurricane, O.; Lawrence Livermore National Lab Team; CEA/DAM Team

    2015-11-01

    The rugby hohlraum design is aimed at providing uniform x-ray drive on the capsule while minimizing the need for crossed beam energy transfer (CBET). As part of a series of experiments at the NIF using rugby hohlraums, design improvements in dual axis shock tuning experiments produced some of the most symmetric shocks measured on implosion experiments at the NIF. Additionally, tuning of the in-flight shell and hot spot shape have demonstrated that capsules can be tuned between oblate and prolate with measured velocities of nearly 340 km/s. However, these experimental measurements were accompanied by high levels of Stimulated Raman Scattering (SRS) that may result from the long inner beam path length, reamplification of the inner SRS by the outers, significant (CBET) or a combination of these. All rugby shots results were achieved with lower levels of hot electrons that can preheat the DT fuel layer for increased adiabat and reduced areal density. Detailed results from these experiments and those planned throughout the summer will be presented and compared with results obtained from cylindrical hohlraums. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Lab under Contract DE-AC52-07NA27344.

  6. Exploring symmetry in near-vacuum hohlraums

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L.; Le Pape, S.; Divol, L.; Meezan, N.; MacKinnon, A.; Ho, D. D.; Jones, O.; Khan, S.; Ma, T.; Milovich, J.; Pak, A.; Ross, J. S.; Thomas, C.; Turnbull, D.; Amendt, P.; Wilks, S.; Zylstra, A.; Rinderknecht, H.; Sio, H.; Petrasso, R.

    2015-11-01

    Recent experiments with near-vacuum hohlraums, which utilize a minimal but non-zero helium fill, have demonstrated performance improvements relative to conventional gas-filled (0.96 - 1.6 mg/cc helium) hohlraums: minimal backscatter, reduced capsule drive degradation, and minimal suprathermal electron generation. Because this is a low laser-plasma interaction platform, implosion symmetry is controlled via pulse-shaping adjustments to laser power balance. Extending this platform to high-yield designs with high-density carbon capsules requires achieving adequate symmetry control throughout the pulse. In simulations, laser propagation is degraded suddenly by hohlraum wall expansion interacting with ablated capsule material. Nominal radiation-hydrodynamics simulations have not yet proven predictive on symmetry of the final hotspot, and experiments show more prolate symmetry than preshot calculations. Recent efforts have focused on understanding the discrepancy between simulated and measured symmetry and on alternate designs for symmetry control through varying cone fraction, trade-offs between laser power and energy, and modifications to case-to-capsule ratio. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  7. Progress in hohlraum physics for the National Ignition Facilitya)

    NASA Astrophysics Data System (ADS)

    Moody, J. D.; Callahan, D. A.; Hinkel, D. E.; Amendt, P. A.; Baker, K. L.; Bradley, D.; Celliers, P. M.; Dewald, E. L.; Divol, L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Jones, O.; Haan, S. W.; Ho, D.; Hopkins, L. B.; Izumi, N.; Kalantar, D.; Kauffman, R. L.; Kilkenny, J. D.; Landen, O.; Lasinski, B.; LePape, S.; Ma, T.; MacGowan, B. J.; MacLaren, S. A.; Mackinnon, A. J.; Meeker, D.; Meezan, N.; Michel, P.; Milovich, J. L.; Munro, D.; Pak, A. E.; Rosen, M.; Ralph, J.; Robey, H. F.; Ross, J. S.; Schneider, M. B.; Strozzi, D.; Storm, E.; Thomas, C.; Town, R. P. J.; Widmann, K. L.; Kline, J.; Kyrala, G.; Nikroo, A.; Boehly, T.; Moore, A. S.; Glenzer, S. H.

    2014-05-01

    Advances in hohlraums for inertial confinement fusion at the National Ignition Facility (NIF) were made this past year in hohlraum efficiency, dynamic shape control, and hot electron and x-ray preheat control. Recent experiments are exploring hohlraum behavior over a large landscape of parameters by changing the hohlraum shape, gas-fill, and laser pulse. Radiation hydrodynamic modeling, which uses measured backscatter, shows that gas-filled hohlraums utilize between 60% and 75% of the laser power to match the measured bang-time, whereas near-vacuum hohlraums utilize 98%. Experiments seem to be pointing to deficiencies in the hohlraum (instead of capsule) modeling to explain most of the inefficiency in gas-filled targets. Experiments have begun quantifying the Cross Beam Energy Transfer (CBET) rate at several points in time for hohlraum experiments that utilize CBET for implosion symmetry. These measurements will allow better control of the dynamic implosion symmetry for these targets. New techniques are being developed to measure the hot electron energy and energy spectra generated at both early and late time. Rugby hohlraums offer a target which requires little to no CBET and may be less vulnerable to undesirable dynamic symmetry "swings." A method for detecting the effect of the energetic electrons on the fuel offers a direct measure of the hot electron effects as well as a means to test energetic electron mitigation methods. At higher hohlraum radiation temperatures (including near vacuum hohlraums), the increased hard x-rays (1.8-4 keV) may pose an x-ray preheat problem. Future experiments will explore controlling these x-rays with advanced wall materials.

  8. Octahedral spherical hohlraum and its laser arrangement for inertial fusion

    SciTech Connect

    Lan, Ke; He, Xian-Tu; Liu, Jie; Zheng, Wudi; Lai, Dongxian

    2014-05-15

    A recent publication [K. Lan et al., Phys. Plasmas 21, 010704 (2014)] proposed a spherical hohlraum with six laser entrance holes of octahedral symmetry at a specific hohlraum-to-capsule radius ratio of 5.14 for inertial fusion study, which has robust high symmetry during the capsule implosion and superiority on low backscatter without supplementary technology. This paper extends the previous one by studying the laser arrangement and constraints of octahedral hohlraum in detail. As a result, it has serious beam crossing at θ{sub L}≤45°, and θ{sub L}=50° to 60° is proposed as the optimum candidate range for the golden octahedral hohlraum, here θ{sub L} is the opening angle that the laser quad beam makes with the Laser Entrance Hole (LEH) normal direction. In addition, the design of the LEH azimuthal angle should avoid laser spot overlapping on hohlraum wall and laser beam transferring outside hohlraum from a neighbor LEH. The octahedral hohlraums are flexible and can be applicable to diverse inertial fusion drive approaches. This paper also applies the octahedral hohlraum to the recent proposed hybrid indirect-direct drive approach.

  9. First Investigation on the Radiation Field of the Spherical Hohlraum.

    PubMed

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xuefei; Lan, Ke; Liu, Jie; Ren, Guoli; Li, Yongsheng; Liu, Yonggang; Jiang, Xiaohua; Yang, Dong; Li, Sanwei; Guo, Liang; Zhang, Huan; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2016-07-08

    The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M-band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

  10. First Investigation on the Radiation Field of the Spherical Hohlraum

    NASA Astrophysics Data System (ADS)

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xuefei; Lan, Ke; Liu, Jie; Ren, Guoli; Li, Yongsheng; Liu, Yonggang; Jiang, Xiaohua; Yang, Dong; Li, Sanwei; Guo, Liang; Zhang, Huan; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2016-07-01

    The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M -band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

  11. Comparison of the laser spot movement inside cylindrical and spherical hohlraums

    NASA Astrophysics Data System (ADS)

    Li, Zhichao; Yang, Dong; Li, Sanwei; Huo, Wen Yi; Lan, Ke; Liu, Jie; Ren, Guoli; Chen, Yao-Hua; Yang, Zhiwen; Guo, Liang; Hou, Lifei; Xie, Xuefei; Li, Yukun; Deng, Keli; Yuan, Zheng; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Jiang, Shaoen; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2017-07-01

    Compared with cylindrical hohlraums, the octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the whole capsule implosion process in indirect drive inertial confinement fusion. However, the narrow space between laser beams and the hohlraum wall may disturb laser propagation inside the spherical hohlraum. In this work, the laser propagation inside the spherical hohlraum and cylindrical hohlraum is investigated experimentally by measuring laser spot movement at the SGIII-prototype laser facility. The experimental results show that the laser propagations inside the spherical hohlraum and the cylindrical hohlraum are totally different from each other due to different hohlraum structures. For the spherical hohlraum, although the laser energy is mainly deposited in the initial position of the laser spot during the whole laser pulse, some laser energies are absorbed by the ablated plasmas from the hohlraum wall. Because the laser beam is refracted by the thin plasmas near the laser entrance hole (LEH) region, the laser spot in the spherical hohlraum moves toward the opposite LEH. In contrast, the laser spot in the cylindrical hohlraum moves toward the LEH along the laser path due to the plasma expansion. When the laser is to be turned off, the accumulated plasmas near the LEH region in the cylindrical hohlraum absorb a majority of laser energy and hinder the laser arriving at the appointed position on the hohlraum wall.

  12. Indirect-drive radiation uniformity in tetrahedral hohlraums

    SciTech Connect

    Schnittman, J.D.; Craxton, R.S.

    1996-10-01

    Tetrahedral hohlraums, by which are understood spherical hohlraums with four laser entrance holes (LEH{close_quote}s) placed at or near the vertices of a tetrahedron, are proposed for the National Ignition Facility (NIF) [J. Lindl, Phys. Plasmas {bold 2}, 3933 (1995)] and the upgraded OMEGA laser [T. R. Boehly {ital et} {ital al}., Rev. Sci. Instrum. {bold 66}, 508 (1995)]. All but four of the 48 NIF beams can irradiate a tetrahedral hohlraum, assuming that 72 beam ports are provided to accommodate direct drive. On OMEGA, the target chamber provides an exact tetrahedral symmetry, permitting the irradiation of tetrahedral hohlraums with all 60 beams. Hohlraum designs are optimized using a new three-dimensional view-factor program called Buttercup, which traces all beam paths through the hohlraum and calculates the radiation flux on the capsule for different values of the albedo. Good irradiation uniformity ({approximately}2{percent} rms) can be obtained on the capsule at all times during the implosion, even with identical beam temporal histories, in contrast to the case of cylindrical hohlraums where {open_quote}{open_quote}beam phasing{close_quote}{close_quote} is needed. {copyright} {ital 1996 American Institute of Physics.}

  13. Indirect-drive radiation uniformity in tetrahedral hohlraums

    NASA Astrophysics Data System (ADS)

    Schnittman, J. D.; Craxton, R. S.

    1996-10-01

    Tetrahedral hohlraums, by which are understood spherical hohlraums with four laser entrance holes (LEH's) placed at or near the vertices of a tetrahedron, are proposed for the National Ignition Facility (NIF) [J. Lindl, Phys. Plasmas 2, 3933 (1995)] and the upgraded OMEGA laser [T. R. Boehly et al., Rev. Sci. Instrum. 66, 508 (1995)]. All but four of the 48 NIF beams can irradiate a tetrahedral hohlraum, assuming that 72 beam ports are provided to accommodate direct drive. On OMEGA, the target chamber provides an exact tetrahedral symmetry, permitting the irradiation of tetrahedral hohlraums with all 60 beams. Hohlraum designs are optimized using a new three-dimensional view-factor program called Buttercup, which traces all beam paths through the hohlraum and calculates the radiation flux on the capsule for different values of the albedo. Good irradiation uniformity (˜2% rms) can be obtained on the capsule at all times during the implosion, even with identical beam temporal histories, in contrast to the case of cylindrical hohlraums where ``beam phasing'' is needed.

  14. Gas-filled hohlraum study on Shenguang-III prototype

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Li, Sanwei; Li, Zhichao; Yi, Rongqing; Guo, Liang; Jiang, Xiaohua; Liu, Shenye; Yang, Jiamin; Jiang, Shaoen; Ding, Yongkun; Hao, Liang; Zhang, Huasen; Zhao, Yiqing; Zou, Shiyang; Huo, Wenyi; Li, Xin

    2015-11-01

    Experimental studies on gas-filled hohlraum were performed extensively in recent years on Shenguang-III prototype laser facility. These experiments employed Au hohlraums within C5H12 gas fill heated by smoothing beams. In the first round of experiments, although the low-Z gas fill impeded the blow-off plasma ablated from hohlraum wall, the x-ray flux from the LEH decreased dramatically compared with the vacuum hohlraum. Further analysis of several ways of energy deposition including heating the gas-fill, extra scattered light and ablating the LEH membrane, revealed that too much laser energy were wasted in exploding the LEH membrane if we use a 1 ns square pulse. After we introduced a low power prepulse to intentionally exploding the membrane, the behavior of the x-ray flux from the gas-filled hohlraum is identical with the vacuum hohlraum. In subsequent studies, the motion of x-ray spot and corona plasma has also been studied using the gas-filled hohlraum. We obtained high quality data of the gas/wall interface and the boundary of the ablated wall near the LEH. The result agrees with that in simulation. However, there is a discrepancy between the experiment and the simulation in the spatial feature of the ablated wall near the LEH extracted from M-band x-ray image.

  15. Capsule Implosion Symmetry in OMEGA Tetrahedral Hohlraums

    NASA Astrophysics Data System (ADS)

    Schnittman, J. D.; Craxton, R. S.; Pollaine, S. M.; Turner, R. E.; Wallace, J. M.; Murphy, T. J.; Delamater, N. D.; Oertel, J. A.; Hauer, A. A.; Klare, K. A.

    1998-11-01

    The 3-D time-dependent capsule implosion symmetry has been calculated for spherical hohlraums with four laser entrance holes. The code BUTTERCUP calculates the locations of beam spots on the hohlraum wall and includes a model for the absorption and x-ray conversion of the laser energy. The gold wall is heated by 1-D radiation diffusion, and radiation transport is carried out with a 3-D view-factor algorithm. A simple hydrodynamic calculation of the imploding capsule gives the resulting 3-D time-dependent drive symmetry. The predicted radiation uniformity incident on the capsule is very good ( ~1% rms) throughout the laser pulse. Experimental images of the capsule show round implosions with convergence ratios of 10 for standard capsules,(T. J. Murphy, Bull. Am. Phys. Soc. 42), 2008 (1997). in agreement with predictions. Radiation temperatures and capsule trajectories are calculated and show good agreement with experiment. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  16. Laser plasma interaction on rugby hohlraum on the Omega Laser Facility: Comparisons between cylinder, rugby, and elliptical hohlraums

    NASA Astrophysics Data System (ADS)

    Masson-Laborde, P. E.; Monteil, M. C.; Tassin, V.; Philippe, F.; Gauthier, P.; Casner, A.; Depierreux, S.; Neuville, C.; Villette, B.; Laffite, S.; Seytor, P.; Fremerye, P.; Seka, W.; Teychenné, D.; Debayle, A.; Marion, D.; Loiseau, P.; Casanova, M.

    2016-02-01

    Gas-filled rugby-shaped hohlraums have demonstrated high performances compared to a classical similar diameter cylinder hohlraum with a nearly 40% increase of x-ray drive, 10% higher measured peak drive temperature, and an increase in neutron production. Experimental comparisons have been done between rugby, cylinder, and elliptical hohlraums. The impact of these geometry differences on the laser plasma instabilities is examined. Using comparisons with hydrodynamic simulations carried out with the code FCI2 and postprocessed by Piranah, we have been able to reproduce the stimulated Raman and Brillouin scattering spectrum of the different beams. Using a methodology based on a statistical analysis for the gain calculations, we show that the behavior of the laser plasma instabilities in rugby hohlraums can be reproduced. The efficiency of laser smoothing techniques to mitigate these instabilities are discussed, and we show that while rugby hohlraums exhibit more laser plasma instabilities than cylinder hohlraum, the latter can be mitigated in the case of an elliptical hohlraum.

  17. A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition

    PubMed Central

    Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Liling; Ding, Yongkun; Jiang, Shaoen; Liu, Jie; Zheng, Jian

    2016-01-01

    A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is orthogonally jointed of three cylindrical hohlraums. Laser beams are injected through every entrance hole with the same incident angle of 55°. A view-factor simulation result shows that the time-varying drive asymmetry of TACH is less than 1.0% in the whole drive pulse period without any supplementary technology. Coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to that of typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, TACH combines most advantages of various hohlraums and has little predictable risk, providing an important competitive candidate for ignition hohlraum. PMID:27703250

  18. A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition

    NASA Astrophysics Data System (ADS)

    Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Liling; Ding, Yongkun; Jiang, Shaoen; Liu, Jie; Zheng, Jian

    2016-10-01

    A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is orthogonally jointed of three cylindrical hohlraums. Laser beams are injected through every entrance hole with the same incident angle of 55°. A view-factor simulation result shows that the time-varying drive asymmetry of TACH is less than 1.0% in the whole drive pulse period without any supplementary technology. Coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to that of typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, TACH combines most advantages of various hohlraums and has little predictable risk, providing an important competitive candidate for ignition hohlraum.

  19. A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition

    NASA Astrophysics Data System (ADS)

    Jiang, Shaoen; Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Lilin; Ding, Yongkun; Zheng, Jian; Liu, Jie

    2016-10-01

    A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named as three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is made of three cylindrical hohlraums orthogonally jointed. Laser beams are injected through every entrance hole with the same incident angle of 55°. The view-factor simulation result shows that the time-varying drive asymmetry of TACH is no more than 1.0% in the whole drive pulse period without any supplementary technology such as beam phasing etc. Its coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, the proposed hohlraum provides a competitive candidate for ignition hohlraum.

  20. Laser-plasma interactions and implosion symmetry in rugby hohlraums

    NASA Astrophysics Data System (ADS)

    Michel, Pierre; Berger, R. L.; Lasinski, B. F.; Ross, J. S.; Divol, L.; Williams, E. A.; Meeker, D.; Langdon, B. A.; Park, H.; Amendt, P.

    2011-10-01

    Cross-beam energy transfer is studied in the context of ``rugby''-hohlraum experiments at the Omega laser facility in FY11, in preparation for future NIF experiments. The transfer acts in opposite direction between rugby and cylinder hohlraums due to the different beam pointing geometries and flow patterns. Its interaction with backscatter is also different as both happen in similar regions inside rugby hohlraums. We will analyze the effects of non-linearities and temporal beam smoothing on energy transfer using the code pF3d. Calculations will be compared to experiments at Omega; analysis of future rugby hohlraum experiments on NIF will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  1. Kinetic modeling of Nernst effect in magnetized hohlraums.

    PubMed

    Joglekar, A S; Ridgers, C P; Kingham, R J; Thomas, A G R

    2016-04-01

    We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.

  2. Kinetic modeling of Nernst effect in magnetized hohlraums

    NASA Astrophysics Data System (ADS)

    Joglekar, A. S.; Ridgers, C. P.; Kingham, R. J.; Thomas, A. G. R.

    2016-04-01

    We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.

  3. Approach to Developing Predictive Capability for Hohlraum Drive and Symmetry

    SciTech Connect

    Jones, O. S.

    2015-07-22

    Currently, we do not have the ability to predict the hohlraum drive and symmetry without requiring ad hoc adjustments to physics models. This document describes a plan for code improvements and focused physics validation experiments.

  4. X-ray diagnostics of hohlraum plasma flow

    SciTech Connect

    Back, C.A.; Glenzer, S.H.; Landen, O.L.; MacGowan, B.J.; Shepard, T.D.

    1996-05-13

    In this study we use spectroscopy and x-ray imaging to investigate the macroscopic plasma flow in mm-sized laser-produced hohlraum plasmas. By using multiple diagnostics to triangulate the emission on a single experiment, we can pinpoint the position of dopants placed inside the hohlraum. X-ray emission from the foil has been used in the past to measure electron temperature. Here we analyze the spatial movement of dopant plasmas for comparison to hydrodynamic calculations.

  5. Characterizing the hohlraum radiation via one-end driven experiments

    NASA Astrophysics Data System (ADS)

    Zhao, Yiqing; Zou, Shiyang; Li, Sanwei; Li, Zhichao; Guo, Liang

    2014-07-01

    A new experiment is designed and performed on the Shenguang III laser facility with the first eight available beams to characterizing the hohlraum radiation, in which the hohlraum with laser entrance holes on both ends is driven through one-end only. The experiment enables us to identify the x-ray radiations originated from the hohlraum reemission wall and high-Z bubble plasmas utilizing their position and spectral characters, which provides a better test on the associated hohlraum models. The total and M-band x-ray radiation fluxes are measured with the flat response x-ray detectors and the filtered M-band x-ray detectors, respectively. Numerical simulations are conducted with the two-dimensional radiation hydrodynamic code LARED-INTEGRATION using the multi-group radiation transfer and/or diffusion models. It is found that the experimentally measured temporal profiles and angular distributions of hohlraum radiation are in good agreement with the predictions of simulation using radiation transfer models, but differ significantly from the results obtained with the multi-group radiation diffusion calculations. We thus note that to accurately represent the hohlraum radiation, a true radiation transfer model is essential.

  6. Laser plasma interaction in rugby-shaped hohlraums

    NASA Astrophysics Data System (ADS)

    Masson-Laborde, P.-E.; Philippe, F.; Tassin, V.; Monteil, M.-C.; Gauthier, P.; Casner, A.; Depierreux, S.; Seytor, P.; Teychenne, D.; Loiseau, P.; Freymerie, P.

    2014-10-01

    Rugby shaped-hohlraum has proven to give high performance compared to a classical similar-diameter cylinder hohlraum. Due to this performance, this hohlraum has been chosen as baseline ignition target for the Laser MegaJoule (LMJ). Many experiments have therefore been performed during the last years on the Omega laser facility in order to study in details the rugby hohlraum. In this talk, we will discuss the interpretation of these experiments from the point of view of the laser plasma instability problem. Experimental comparisons have been done between rugby, cylinder and elliptical shape rugby hohlraums and we will discuss how the geometry differences will affect the evolution of laser plasma instabilities (LPI). The efficiency of laser smoothing techniques on these instabilities will also be discussed as well as gas filling effect. The experimental results will be compared with FCI2 hydroradiative calculations and linear postprocessing with Piranah. Experimental Raman and Brillouin spectrum, from which we can infer the location of the parametric instabilities, will be compared to simulated ones, and will give the possibility to compare LPI between the different hohlraum geometries.

  7. Illumination of 3 and 4 hole spherical laser driven hohlraums

    SciTech Connect

    Wilson, D.C.; Wingate, C.A.; Mead, W.C.; McLeod, J.

    1990-01-01

    We have considered what laser beam orientations entering static spherical hohlraums through three or four holes are needed to uniformly distribute the incident laser energy on the hohlraum wall. Each incident beam is characterized by its angle of incidence, i, with respect to the normal to the laser entrance hole. In the set of beams needed to cover the hohlraum interior, let i{sub min} be the minimum angle of incidence of beams in this set, i.e. the beam which most closely approaches the center. Let i{sub max} be the beam which passes most obliquely through the entrance hole. To leave the maximum unexposed central volume we desire the largest i{sub min}. To minimize the entrance hole diameter i{sub max} should be minimized. For a hohlraum with three holes located 120{degree} apart in a plane through the hohlraum center, the wall can be covered uniformly by a set of beams with i{sub min} = 30{degree} and i{sub max} = 60{degree}. For a hohlraum with four holes located at the corners of a tetrahedron there exist two sets, one with i{sub min} = 27.3{degree} and i{sub max} = 54.6{degree}, and another with i{sub min} = 35.4{degree} and i{sub max} = 62.6{degree}.

  8. The Hohlraum Drive Campaign on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Moody, John D.

    2013-10-01

    The Hohlraum drive effort on the National Ignition Facility (NIF) laser has three primary goals: 1) improve hohlraum performance by improving laser beam propagation, reducing backscatter from laser plasma interactions (LPI), controlling x-ray and electron preheat, and modifying the x-ray drive spectrum; 2) improve understanding of crossbeam energy transfer physics to better evaluate this as a symmetry tuning method; and 3) improve modeling in order to find optimum designs. Our experimental strategy for improving performance explores the impact of significant changes to the hohlraum shape, wall material, gasfill composition, and gasfill density on integrated implosion experiments. We are investigating the performance of a rugby-shaped design that has a significantly larger diameter (7 mm) at the waist than our standard 5.75 mm diameter cylindrical-shaped hohlraum but maintains approximately the same wall area. We are also exploring changes to the gasfill composition in cylindrical hohlraums by using neopentane at room temperature to compare with our standard helium gasfill. In addition, we are also investigating higher He gasfill density (1.6 mg/cc vs nominal 0.96 mg/cc) and increased x-ray drive very early in the pulse. Besides these integrated experiments, our strategy includes experiments testing separate aspects of the hohlraum physics. These include time-resolved and time-integrated measurements of cross-beam transfer rates and laser-beam spatial power distribution at early and late times using modified targets. Non-local thermal equilibrium modeling and heat transport relevant to ignition experiments are being studied using sphere targets on the Omega laser system. These simpler targets provide benchmarks for improving our modeling tools. This talk will summarize the results of the Hohlraum Drive campaign and discuss future directions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under

  9. Gas-filled hohlraum experiments at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    FernáNdez, Juan C.

    2005-10-01

    A joint team from the National Laboratories at Los Alamos (LANL) and Lawrence Livermore (LLNL) has fielded the first gas-filled hohlraum experiments at the National Ignition Facility (NIF) laser, with the available four beams arranged as a single f/8 beam. The gas-fill in this LANL design provides plasma pressure to tamp the hohlraum gold wall to avoid filling, the same technique used in ignition designs. A shaped laser pulse 8 ns in duration was used, with a low-power foot and a late peak of 7 TW, a contrast ratio exceeding 100 (the highest on NIF so far), and a total energy of 14 kJ. Deployed measurements include laser energy and power; back-scattered light spectrum, power and energy directly into the focusing lenses; back-scattered laser light energy outside the lenses; soft x-ray drive spectrum and power, and; gated framing-camera images of the hohlraum self-emission with x-ray energy > 10 keV. Our main results and conclusions are: (1) This is the first experimental demonstration that a low-Z fill can keep the interior of a laser-driven hohlraum open long enough to ensure efficient coupling of ignition-relevant laser pulses. (2) When backscattering losses are accounted ( 25% reflectivity due to stimulated Brillouin scattering [SBS]), we have the radiation-hydrodynamics predictive capability necessary to understand the energy balance in such hohlraums quantitatively, as well as other details of the hohlraum-plasma evolution. (3) Laser-plasma instabilities (LPI) can lead to considerable laser reflectivity levels, with a significant and measurable deleterious impact on hohlraum energetics. Thus, continued development of LPI predictive capability and understanding is needed. (4) These experiments provide evidence that Stimulated Raman back-scattering losses (SRS) may be minimized with a proper choice of plasma conditions.

  10. Experimental characterization of hohlraum conditions by X-ray spectroscopy

    SciTech Connect

    Back, C.A.; Hsieh, E.J.; Kauffman, R.L.

    1996-06-01

    Spectroscopy is a powerful technique used to measure the plasma parameters relevant to Inertial Confinement Fusion (ICF) plasmas. For instance, the onset of spectral signals from multilayer targets have been used to determine ablation rate scalings. Temperature and density measurements in coronal plasmas have enabled the study of laser coupling efficiency as a function of the laser wavelengths. More recently, dopants have been successfully used to determine capsule conditions of ICF targets. However, few spectroscopic studies have been performed to diagnose plasma conditions of the hohlraum itself. Several laboratories have studied enclosed cavities, previously concentrating on measurements of the radiative heat wave, the x-ray conversion efficiency, and temporal evolution of Au x rays. Measurements of electron temperature T{sub e} and electron densities n{sub e} are difficult because many physical processes occur and each diagnostic`s line-of-sight is restricted by the hohlraum wall. However, they are worth pursuing because they can provide critical information on the target energetics and the evolution of plasma parameters important to achieving fusion. Here the authors discuss spectroscopic tracers to diagnose plasma conditions in the hohlraum, using time- and space-resolved measurements. The tracers are typically mid-Z elements which are placed on the hohlraum wall or supended in the hohlraum volume. To demonstrate the breadth of measurements that can be performed, three types of experiments are presented.

  11. Numerical Simulation of the Radiation Symmetry in Tetrahedral Hohlraums.

    NASA Astrophysics Data System (ADS)

    Macfarlane, J. J.; Magelssen, G.; Delamater, N.; Wallace, J.; Murphy, T.; Klare, K.

    1997-11-01

    The successful implosion of a capsule in indirect-drive ICF experiments requires the ability to diagnose and control the radiation symmetry at its surface. Recently, there has been increased interest in studying whether ``tetrahedral'' hohlraums can produce a radiation field on the capsule which is more symmetric than cylindrical hohlraums. Asymmetries in the 3-D radiation field are influenced by: the size and shape of the hohlraum, the wall albedo, the capsule radius, the LEH and diagnostic holes, and the laser beam pointing and power/energy imbalances. Time-dependent asymmetries are caused by the laser pulse history, changing wall albedos, and wall motion. We have recently developed a 3-D view factor code to investigate the time-dependent radiation asymmetry in indirect-drive ICF experiments. This code includes algorithms for the accurate solution of configuration factors, as well as laser ray-trace algorithms for modeling OMEGA, NOVA, and NIF laser/target chamber geometries. Time-dependent albedos are based on 1-D radiation-hydrodynamics simulations using UTA opacities for the high-Z wall. We will present results from simulations of OMEGA tetrahedral hohlraum experiments, as well as simulations showing how asymmetries scale with capsule/hohlraum configuration.

  12. Energetics of Multiple-Ion Species Hohlraum Plasmas

    SciTech Connect

    Neumayer, P; Berger, R; Callahan, D; Divol, L; Froula, D; London, R; MacGowan, B J; Meezan, N; Michel, P; Ross, J S; Sorce, C; Widmann, K; Suter, L; Glenzer, S H

    2007-11-05

    A study of the laser-plasma interaction processes in multiple-ion species plasmas has been performed in plasmas that are created to emulate the plasma conditions in indirect drive inertial confinement fusion targets. Gas-filled hohlraums with densities of xe22/cc are heated to Te=3keV and backscattered laser light is measured by a suite of absolutely calibrated backscatter diagnostics. Ion Landau damping is increased by adding hydrogen to the CO2/CF4 gas fill. We find that the backscatter from stimulated Brillouin scattering is reduced is monotonically reduced with increasing damping, demonstrating that Landau damping is the controlling damping mechanism in ICF relevant high-electron temperature plasmas. The reduction in backscatter is accompanied by a comparable increase in both transmission of a probe beam and an increased hohlraum radiation temperature, showing that multiple-ion species plasmas improve the overall hohlraum energetics/performance. Comparison of the experimental data to linear gain calculations as well as detailed full-scale 3D laser-plasma interaction simulations show quantitative agreement. Our findings confirm the importance of Landau damping in controlling backscatter from high-electron temperature hohlraum plasmas and have lead to the inclusion of multi-ion species plasmas in the hohlraum point design for upcoming ignition campaigns at the National Ignition Facility.

  13. Numerical Modeling of Hohlraum Radiation Conditions: Spatial and Spectral Variations due to Sample Position, Beam Pointing, and Hohlraum Geometry

    SciTech Connect

    Cohen, D H; Landen, O L; MacFarlane, J J

    2005-01-25

    View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold hohlraums and single-ended gold hohlraums (''halfraums'') used in inertial confinement fusion (ICF) and high energy density (HED) physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the hohlraum ''drive'' can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature, and especially the differences between what diagnostics looking in the LEH measure vs. the radiation temperature on wall-mounted experimental packages, is generally greater for double-ended hohlraums than it is for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, sample position, and beam pointing) that can be adjusted in order to, for example, maximize the radiation flux onto a sample, or other package. In this vein, simulations of hohlraums and halfraums with LEH shields are also presented.

  14. Numerical modeling of Hohlraum radiation conditions: Spatial and spectral variations due to sample position, beam pointing, and Hohlraum geometry

    NASA Astrophysics Data System (ADS)

    Cohen, David H.; Landen, Otto L.; MacFarlane, Joseph J.

    2005-12-01

    View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold Hohlraums and single-ended gold Hohlraums ("halfraums") used in inertial confinement fusion and high-energy density physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the Hohlraum "drive" can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature and especially the differences between what diagnostics looking in the LEH measure versus the radiation temperature on wall-mounted experimental packages are generally greater for double-ended Hohlraums than for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, sample position, and beam pointing) that can be adjusted in order to, for example, maximize the radiation flux onto a sample, or other package. In this vein, simulations of Hohlraums and halfraums with LEH shields are also presented.

  15. Lead (Pb) hohlraum: target for inertial fusion energy.

    PubMed

    Ross, J S; Amendt, P; Atherton, L J; Dunne, M; Glenzer, S H; Lindl, J D; Meeker, D; Moses, E I; Nikroo, A; Wallace, R

    2013-01-01

    Recent progress towards demonstrating inertial confinement fusion (ICF) ignition at the National Ignition Facility (NIF) has sparked wide interest in Laser Inertial Fusion Energy (LIFE) for carbon-free large-scale power generation. A LIFE-based fleet of power plants promises clean energy generation with no greenhouse gas emissions and a virtually limitless, widely available thermonuclear fuel source. For the LIFE concept to be viable, target costs must be minimized while the target material efficiency or x-ray albedo is optimized. Current ICF targets on the NIF utilize a gold or depleted uranium cylindrical radiation cavity (hohlraum) with a plastic capsule at the center that contains the deuterium and tritium fuel. Here we show a direct comparison of gold and lead hohlraums in efficiently ablating deuterium-filled plastic capsules with soft x rays. We report on lead hohlraum performance that is indistinguishable from gold, yet costing only a small fraction.

  16. Lead (Pb) Hohlraum: Target for Inertial Fusion Energy

    PubMed Central

    Ross, J. S.; Amendt, P.; Atherton, L. J.; Dunne, M.; Glenzer, S. H.; Lindl, J. D.; Meeker, D.; Moses, E. I.; Nikroo, A.; Wallace, R.

    2013-01-01

    Recent progress towards demonstrating inertial confinement fusion (ICF) ignition at the National Ignition Facility (NIF) has sparked wide interest in Laser Inertial Fusion Energy (LIFE) for carbon-free large-scale power generation. A LIFE-based fleet of power plants promises clean energy generation with no greenhouse gas emissions and a virtually limitless, widely available thermonuclear fuel source. For the LIFE concept to be viable, target costs must be minimized while the target material efficiency or x-ray albedo is optimized. Current ICF targets on the NIF utilize a gold or depleted uranium cylindrical radiation cavity (hohlraum) with a plastic capsule at the center that contains the deuterium and tritium fuel. Here we show a direct comparison of gold and lead hohlraums in efficiently ablating deuterium-filled plastic capsules with soft x rays. We report on lead hohlraum performance that is indistinguishable from gold, yet costing only a small fraction. PMID:23486285

  17. Demonstration of Enhanced Radiation Drive in Hohlraums Made with High-Z Mixture "Cocktail" Wall Material

    SciTech Connect

    Schein, J; Jones, O; Rosen, M; Dewald, E; Glenzer, S; Gunther, J; Hammel, B; Landen, O; Suter, L; Wallace, R

    2007-02-06

    We present results from experiments, numerical simulations and analytic modeling, demonstrating enhanced hohlraum performance. Care in the fabrication and handling of hohlraums with walls consisting of high-Z mixtures (cocktails) has led to our demonstration, for the first time, of a significant increase in radiation temperature compared to a pure Au hohlraum that is in agreement with predictions and is ascribable to reduced wall losses. This data suggests that a NIF ignition hohlraum made of a U:Au:Dy cocktail should have {approx}17% reduction in wall losses compared to a similar gold hohlraum.

  18. Measurement and simulation of apertures on Z hohlraums

    SciTech Connect

    Chrien, R.E.; Matuska, W. Jr.; Swenson, F.J.

    1998-12-01

    The authors have performed aperture measurements and simulations for vacuum hohlraums heated by wire array implosions. A low-Z plastic coating is often applied to the aperture to create a high ablation pressure which retards the expansion of the gold hohlraum wall. However, this interface is unstable and may be subjects to the development of highly nonlinear perturbations (jets) as a result of shocks converging near the edge of the aperture. These experiments have been simulated using Lagrangian and Eulerian radiation hydrodynamics codes.

  19. Late-time hohlraum pressure dynamics in supernova remnant experiments

    NASA Astrophysics Data System (ADS)

    Hurricane, O. A.; Glendinning, S. G.; Remington, B. A.; Drake, R. P.; Dannenberg, K. K.

    2001-06-01

    It is shown that laser driven hohlraums obtain significant internal pressures which affect the hydrodynamics of high-energy density shock-tube experiments. By incorporating this previously neglected hohlraum pressure effect (in addition to the usual x-ray drive) into computer simulations which model the NOVA laser driven supernova remnant experiment [R. P. Drake, S. G. Glendinning, K. Estabrook, B. A. Remington, R. McCray, R. J. Williams, L. J. Suter, T. B. Smith, J. J. Carroll III, R. A. London, and E. Liang, Phys. Rev. Lett. 81, 2068 (1998)], calculations are able to reproduce the observed structure of hydrodynamic features.

  20. Scaling and optimization of the radiation temperature in dynamic hohlraums

    SciTech Connect

    SLUTZ,STEPHEN A.; DOUGLAS,MELISSA R.; LASH,JOEL S.; VESEY,ROGER A.; CHANDLER,GORDON A.; NASH,THOMAS J.; DERZON,MARK S.

    2000-04-13

    The authors have constructed a quasi-analytic model of the dynamic hohlraum. Solutions only require a numerical root solve, which can be done very quickly. Results of the model are compared to both experiments and full numerical simulations with good agreement. The computational simplicity of the model allows one to find the behavior of the hohlraum temperature as a function the various parameters of the system and thus find optimum parameters as a function of the driving current. The model is used to investigate the benefits of ablative standoff and axial convergence.

  1. Thickness distribution for gold and copper electroformed hohlraums

    SciTech Connect

    Elsner, F.

    1999-03-01

    Some preliminary experiments have been performed to determine the effect of mandrel geometry and plating both composition on the thickness uniformity of gold and copper electroformed hohlraums. It was observed that for gold plating, the edge radius has a dramatic influence on uniformity in a direction opposite that expected (i.e., uniformity worsened with larger radius) and that extension of the front small-diameter cylinder gave a slight improvement in hohlraum symmetry. In the case of copper plating it was found that, as expected, reduced metal concentration improved uniformity, however, it was also found that the selection of additives has an even more pronounced effect.

  2. Electron Temperature and Plasma Flow Measurements of NIF Hohlraum Plasmas

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brow, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Eder, D.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; LLNL Collaboration; LLE Collaboration; GA Collaboration; SNL Collaboration

    2016-10-01

    Characterizing the plasma conditions inside NIF hohlraums, in particular mapping the plasma Te, is critical to gaining insight into mechanisms that affect energy coupling and transport in the hohlraum. The dot spectroscopy platform provides a temporal history of the localized Te and plasma flow inside a NIF hohlraum, by introducing a Mn-Co tracer dot, at strategic locations inside the hohlraum, that comes to equilibrium with the local plasma. K-shell X-ray spectroscopy of the tracer dot is recorded onto an absolutely calibrated X-ray streak spectrometer. Isoelectronic and interstage line ratios are used to infer localized Te through comparison with atomic physics calculations using SCRAM. Time resolved X-ray images are simultaneously taken of the expanding dot, providing plasma (ion) flow information. We present recent results provided by this platform and compare with simulations using HYDRA. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  3. Mitigating Stimulated Raman Scattering in Hohlraum Plasmas Using Magnetic Insulation

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Albright, B. J.; Kline, J. L.; Yin, L.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.; MacDonald, M. J.

    2013-10-01

    Controlling stimulated Raman scattering (SRS) in hohlraum plasmas is important for achieving high-gain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense low-Z plasma to the dense high-Z hohlraum wall. This leads to weaker Landau damping and stronger growth of SRS. Magnetic insulation of the heat conducting electrons can occur when the Hall parameter ωceτei >> 1, where ωce is the electron-cyclotron frequency, and τei is the electron-ion collision time. For NIF laser-plasma conditions, it is shown that a 10-T external magnetic field may substantially reduce cross-field transport and may increase coronal plasma temperatures, thus increasing linear Landau damping and mitigating SRS. We will present calculations and simulations supporting this concept, and will present initial results from Omega experiments using gas-filled hohlraums with external B-fields up to 10-T. Work performed under the auspices of DOE by LANL under contract DE-AC52-06NA25396.

  4. Laser-plasma interactions in large gas-filled hohlraums

    SciTech Connect

    Turner, R.E.; Powers, L.V.; Berger, R.L.

    1996-06-01

    Indirect-drive targets planned for the National Ignition Facility (NIF) laser consist of spherical fuel capsules enclosed in cylindrical Au hohlraums. Laser beams, arranged in cylindrical rings, heat the inside of the Au wall to produce x rays that in turn heat and implode the capsule to produce fusion conditions in the fuel. Detailed calculations show that adequate implosion symmetry can be maintained by filling the hohlraum interior with low-density, low-Z gases. The plasma produced from the heated gas provides sufficient pressure to keep the radiating Au surface from expanding excessively. As the laser heats this gas, the gas becomes a relatively uniform plasma with small gradients in velocity and density. Such long-scale-length plasmas can be ideal mediums for stimulated Brillouin Scattering (SBS). SBS can reflect a large fraction of the incident laser light before it is absorbed by the hohlraum; therefore, it is undesirable in an inertial confinement fusion target. To examine the importance of SBS in NIF targets, the authors used Nova to measure SBS from hohlraums with plasma conditions similar to those predicted for high-gain NIF targets. The plasmas differ from the more familiar exploding foil or solid targets as follows: they are hot (3 keV); they have high electron densities (n{sub e}=10{sup 21}cm{sup {minus}3}); and they are nearly stationary, confined within an Au cylinder, and uniform over large distances (>2 mm). These hohlraums have <3% peak SBS backscatter for an interaction beam with intensities of 1-4 x 10{sup 15} W/cm{sup 2}, a laser wavelength of 0.351{micro}m, f/4 or f/8 focusing optics, and a variety of beam smoothing implementations. Based on these conditions the authors conclude that SBS does not appear to be a problem for NIF targets.

  5. Analysis of the National Ignition Facility Ignition Hohlraum Energetics Experiments

    SciTech Connect

    Town, R J; Rosen, M D; Michel, P A; Divol, L; Moody, J D; Kyrala, G A; Schneider, M B; Kline, J L; Thomas, C A; Milovich, J L; Callahan, D A; Meezan, N B; Hinkel, D E; Williams, E A; Berger, R L; Edwards, M J; Suter, L J; Haan, S W; Lindl, J D; Dixit, S; Glenzer, S H; Landen, O L; Moses, E I; Scott, H A; Harte, J A; Zimmerman, G B

    2010-11-22

    A series of forty experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] to study energy balance and implosion symmetry in reduced- and full-scale ignition hohlraums was shot at energies up to 1.3 MJ. This paper reports the findings of the analysis of the ensemble of experimental data obtained that has produced an improved model for simulating ignition hohlraums. Last year the first observation in a NIF hohlraum of energy transfer between cones of beams as a function of wavelength shift between those cones was reported [P. Michel, et al, Phys of Plasmas, 17, 056305, (2010)]. Detailed analysis of hohlraum wall emission as measured through the laser entrance hole (LEH) has allowed the amount of energy transferred versus wavelength shift to be quantified. The change in outer beam brightness is found to be quantitatively consistent with LASNEX [G. B. Zimmerman and W. L. Kruer, Comments Plasma Phys. Control. Fusion 2, 51 (1975)] simulations using the predicted energy transfer when possible saturation of the plasma wave mediating the transfer is included. The effect of the predicted energy transfer on implosion symmetry is also found to be in good agreement with gated x-ray framing camera images. Hohlraum energy balance, as measured by x-ray power escaping the LEH, is quantitatively consistent with revised estimates of backscatter and incident laser energy combined with a more rigorous non-local-thermodynamic-equilibrium atomic physics model with greater emissivity than the simpler average-atom model used in the original design of NIF targets.

  6. Characterization of Blistering and Delamination in Depleted Uranium Hohlraums

    SciTech Connect

    Biobaum, K. J. M.

    2013-03-01

    Blistering and delamination are the primary failure mechanisms during the processing of depleted uranium (DU) hohlraums. These hohlraums consist of a sputter-deposited DU layer sandwiched between two sputter-deposited layers of gold; a final thick gold layer is electrodeposited on the exterior. The hohlraum is deposited on a copper-coated aluminum mandrel; the Al and Cu are removed with chemical etching after the gold and DU layers are deposited. After the mandrel is removed, blistering and delamination are observed on the interiors of some hohlraums, particularly at the radius region. It is hypothesized that blisters are caused by pinholes in the copper and gold layers; etchant leaking through these holes reaches the DU layer and causes it to oxidize, resulting in a blister. Depending on the residual stress in the deposited layers, blistering can initiate larger-scale delamination at layer interfaces. Scanning electron microscopy indicates that inhomogeneities in the machined aluminum mandrel are replicated in the sputter-deposited copper layer. Furthermore, the Cu layer exhibits columnar growth with pinholes that likely allow etchant to come in contact with the gold layer. Any inhomogeneities or pinholes in this initial gold layer then become nucleation sites for blistering. Using a focused ion beam system to etch through the gold layer and extract a cross-sectional sample for transmission electron microscopy, amorphous, intermixed layers at the gold/DU interfaces are observed. Nanometer-sized bubbles in the sputtered and electrodeposited gold layers are also present. Characterization of the morphology and composition of the deposited layers is the first step in determining modifications to processing parameters, with the goal of attaining a significant improvement in hohlraum yield.

  7. Laser beam propagation through inertial confinement fusion hohlraum plasmas

    SciTech Connect

    Froula, D. H.; Divol, L.; Meezan, N. B.; Dixit, S.; Neumayer, P.; Moody, J. D.; Pollock, B. B.; Ross, J. S.; Suter, L.; Glenzer, S. H.

    2007-05-15

    A study of the laser-plasma interaction processes have been performed in plasmas that are created to emulate the plasma conditions in indirect drive inertial confinement fusion targets. The plasma emulator is produced in a gas-filled hohlraum; a blue 351-nm laser beam propagates along the axis of the hohlraum interacting with a high-temperature (T{sub e}=3.5 keV), dense (n{sub e}=5x10{sup 20} cm{sup -3}), long-scale length (L{approx}2 mm) plasma. Experiments at these conditions have demonstrated that the interaction beam produces less than 1% total backscatter resulting in transmission greater than 90% for laser intensities less than I<2x10{sup 15} W cm{sup -2}. The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows a stimulated Brillouin scattering threshold (R=10%) for a linear gain of 15; these high temperature, low density experiments produce plasma conditions comparable to those along the outer beams in ignition hohlraum designs. By increasing the gas fill density (n{sub e}=10{sup 21} cm{sup -3}) in these targets, the inner beam ignition hohlraum conditions are accessed. In this case, stimulated Raman scattering dominates the backscattering processes and we show that scattering is small for gains less than 20 which can be achieved through proper choice of the laser beam intensity.

  8. Simulation of the hohlraum for a laser facility of Megajoule scale

    NASA Astrophysics Data System (ADS)

    Chizhkov, M. N.; Kozmanov, M. Y. U.; Lebedev, S. N.; Lykov, V. A.; Rykovanova, V. V.; Seleznev, V. N.; Selezneva, K. I.; Stryakhnina, O. V.; Shestakov, A. A.; Vronskiy, A. V.

    2010-08-01

    2D calculations of the promising laser hohlraums were performed with using of the Sinara computer code. These hohlraums are intended for achievement of indirectly-driven thermonuclear ignition at laser energy above 1 MJ. Two calculation variants of the laser assembly with the form close to a rugby ball were carried out: with laser entrance hole shields and without shields. Time dependent hohlraum radiation temperature and x-ray flux asymmetry on a target were obtained.

  9. Novel free-form hohlraum shape design and optimization for laser-driven inertial confinement fusion

    SciTech Connect

    Jiang, Shaoen; Jing, Longfei Ding, Yongkun; Huang, Yunbao

    2014-10-15

    The hohlraum shape attracts considerable attention because there is no successful ignition method for laser-driven inertial confinement fusion at the National Ignition Facility. The available hohlraums are typically designed with simple conic curves, including ellipses, parabolas, arcs, or Lame curves, which allow only a few design parameters for the shape optimization, making it difficult to improve the performance, e.g., the energy coupling efficiency or radiation drive symmetry. A novel free-form hohlraum design and optimization approach based on the non-uniform rational basis spline (NURBS) model is proposed. In the present study, (1) all kinds of hohlraum shapes can be uniformly represented using NURBS, which is greatly beneficial for obtaining the optimal available hohlraum shapes, and (2) such free-form uniform representation enables us to obtain an optimal shape over a large design domain for the hohlraum with a more uniform radiation and higher drive temperature of the fuel capsule. Finally, a hohlraum is optimized and evaluated with respect to the drive temperature and symmetry at the Shenguang III laser facility in China. The drive temperature and symmetry results indicate that such a free-form representation is advantageous over available hohlraum shapes because it can substantially expand the shape design domain so as to obtain an optimal hohlraum with high performance.

  10. Prolate-Spheroid (``Rugby-Shaped'') Hohlraum for Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Vandenboomgaerde, M.; Bastian, J.; Casner, A.; Galmiche, D.; Jadaud, J.-P.; Laffite, S.; Liberatore, S.; Malinie, G.; Philippe, F.

    2007-08-01

    A novel rugby-ball shaped hohlraum is designed in the context of the indirect-drive scheme of inertial-confinement fusion (ICF). Experiments were performed on the OMEGA laser and are the first use of rugby hohlraums for ICF studies. Analysis of experimental data shows that the hohlraum energetics is well understood. We show that the rugby-ball shape exhibits advantages over cylinder, in terms of temperature and of symmetry control of the capsule implosion. Simulations indicate that rugby hohlraum driven targets may be candidates for ignition in a context of early Laser MegaJoule experiments with reduced laser energy.

  11. The Effect of Condensates and Inner Coatings on the Performance of Vacuum Hohlraum Targets

    SciTech Connect

    Boehly, T.R.; Olson, R.E.; Celliers, P.M.; Munro, D.H.; Seka, W.; Landen, O.L.; Collins, G.W.; Suter, L.J.; Sangster, T.C.; Meyerhofer, D.D.

    2010-03-23

    Experiments on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)] using laser-driven vacuum hohlraum targets show distinct differences between cryogenic (<20 K) and warm targets. The cryogenic targets have 15% lower peak radiation temperatures, and the temporal profile of those temperatures is quite different than in warm targets. The cryogenic targets reflect significantly more (3%–7%) of the laser drive than the warm targets (<1%). The temporal and spectral features of the reflected light from the cryogenic targets show a significantly longer duration and more spectral features than the warm hohlraums. Warm hohlraum targets coated with 2 um of CH replicate the behavior of cryogenic targets. This indicates that the cryogenic hohlraums are affected by the condensation of background gases on the cold hohlraum surface. The most important effect of low-Z material in the hohlraums is that they significantly reduce the x-ray conversion efficiency, resulting in lower hohlraum radiation temperature. The coatings (both CH and condensates) produce long-scale-length, low-Z plasmas that moderately reduce the absorption of laser light in the hohlraums. This causes higher reflectivity and produces hot electrons that generate hard x rays (hv > 20 keV), both of which are detrimental to the performance of hohlraum-driven inertial confinement fusion targets.

  12. Investigating the hohlraum radiation properties through the angular distribution of the radiation temperature

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Yang, D.; Song, P.; Zou, S.; Zhao, Y.; Li, S.; Li, Z.; Guo, L.; Wang, F.; Zheng, W.; Gu, P.; Pei, W.; Zhu, S.; Jiang, S.; Ding, Y.

    2016-08-01

    The symmetric radiation drive is essential to the capsule implosion in the indirect drive fusion but is hard to achieve due to the non-uniform radiation distribution inside the hohlraum. In this work, the non-uniform radiation properties of both vacuum and gas-filled hohlraums are studied by investigating the angular distribution of the radiation temperature experimentally and numerically. It is found that the non-uniform radiation distribution inside the hohlraum induces the variation of the radiation temperature between different view angles. The simulations show that both the angular distribution of the radiation temperature and the hohlraum radiation distribution can be affected by the electron heat flux. The measured angular distribution of the radiation temperature is more consistent with the simulations when the electron heat flux limiter f e = 0.1 . Comparisons between the experiments and simulations further indicate that the x-ray emission of the blow-off plasma is overestimated in the simulations when it stagnates around the hohlraum axis. The axial position of the laser spot can also be estimated by the angular distribution of the radiation temperature due to their sensitive dependence. The inferred laser spot moves closer to the laser entrance hole in the gas-filled hohlraum than that in the vacuum hohlraum, consisting with the x-ray images taken from the framing camera. The angular distribution of the radiation temperature provides an effective way to investigate the hohlraum radiation properties and introduces more constraint to the numerical modeling of the hohlraum experiments.

  13. A three wavelength scheme to optimize hohlraum coupling on the National Ignition Facility

    SciTech Connect

    Michel, P; Divol, L; Town, R; Rosen, M

    2010-12-16

    By using three tunable wavelengths on different cones of laser beams on the National Ignition Facility, numerical simulations show that the energy transfer between beams can be tuned to redistribute the energy within the cones of beams most prone to backscatter instabilities. These radiative hydrodynamics and laser-plasma interaction simulations have been tested against large scale hohlraum experiments with two tunable wavelengths, and reproduce the hohlraum energetics and symmetry. Using a third wavelength provides a greater level of control of the laser energy distribution and coupling in the hohlraum, and could significantly reduce stimulated Raman scattering losses and increase the hohlraum radiation drive while maintaining a good implosion symmetry.

  14. Symmetry control in subscale near-vacuum hohlraums

    SciTech Connect

    Turnbull, D.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Mackinnon, A.; Zylstra, A. B.; Rinderknecht, H. G.; Sio, H.; Petrasso, R. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J.

    2016-05-18

    Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. In conclusion, specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

  15. Symmetry control in subscale near-vacuum hohlraums

    DOE PAGES

    Turnbull, D.; Berzak Hopkins, L. F.; Le Pape, S.; ...

    2016-05-18

    Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce mostmore » experimental observables, including hot spot shape, for a majority of implosions. In conclusion, specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.« less

  16. Impeding hohlraum plasma stagnation in inertial-confinement fusion.

    PubMed

    Li, C K; Séguin, F H; Frenje, J A; Rosenberg, M J; Rinderknecht, H G; Zylstra, A B; Petrasso, R D; Amendt, P A; Landen, O L; Mackinnon, A J; Town, R P J; Wilks, S C; Betti, R; Meyerhofer, D D; Soures, J M; Hund, J; Kilkenny, J D; Nikroo, A

    2012-01-13

    This Letter reports the first time-gated proton radiography of the spatial structure and temporal evolution of how the fill gas compresses the wall blowoff, inhibits plasma jet formation, and impedes plasma stagnation in the hohlraum interior. The potential roles of spontaneously generated electric and magnetic fields in the hohlraum dynamics and capsule implosion are discussed. It is shown that interpenetration of the two materials could result from the classical Rayleigh-Taylor instability occurring as the lighter, decelerating ionized fill gas pushes against the heavier, expanding gold wall blowoff. This experiment showed new observations of the effects of the fill gas on x-ray driven implosions, and an improved understanding of these results could impact the ongoing ignition experiments at the National Ignition Facility.

  17. Laser Machining For Fabrication Of Hohlraums And Capsules

    SciTech Connect

    Shirk, M D; Kelly, B T; Haynes, S M; Stuart, B C; Sanchez, J J; Moody, J D; Cook, R C

    2005-06-24

    Laser machining technology has been used to demonstrate the ability to rapidly perform jobs on all aspects of ICF targets. Lasers are able to rapidly perform modifications and repairs to the gold metal parts on hohlraums, make cuts in the delicate polymer parts of the hohlraum, and drill holes in the capsules to enable them to be filled with fuel. Lasers investigated in this work include 193 nm ArF and 248 nm KrF excimers and 810 nm chirped-pulse amplification Ti:Sapphire lasers. The excimer lasers showed a definite advantage in drilling and machining of polymeric materials and the ultrashort infrared pulses of the Ti:Sapphire laser were far better for the gold structures.

  18. Symmetry control in subscale near-vacuum hohlraums

    NASA Astrophysics Data System (ADS)

    Turnbull, D.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Mackinnon, A.; Zylstra, A. B.; Rinderknecht, H. G.; Sio, H.; Petrasso, R. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J.

    2016-05-01

    Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

  19. Radiation temperature measurements in laser-heated hohlraums

    SciTech Connect

    Cobble, J.A.; Goldman, S.R.; Bessarab, A.V.; Kunin, A.V.; Tokarev, V.A.

    1997-11-01

    Two x-ray spectrographs have been used on the Trident laser at LANL to monitor the radiation temperature of small Au hohlraums. The cylindrical targets are smaller than 1 mm. The x radiation produced by {approximately} 400 J of 0.53-{micro}m laser light is detected with a 7-channel VNIIEF soft-x-ray spectrometer. Each channel employs a multi-layer mirror and a filter to limit the channel bandwidth to 1--3% of the channel energy. X rays are detected with calibrated Al x-ray diodes. A second spectrometer is based on a free-standing Au transmission grating for spectral dispersion and a multi-channel diamond photo-conductive device detector. The small hohlraum results are consistent with radiation temperatures exceeding 100 eV. Simple computer modeling shows that late in the plasma discharge, radiation of this temperature is emitted from the target.

  20. Symmetry control in subscale near-vacuum hohlraums

    SciTech Connect

    Turnbull, D. Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J.; Mackinnon, A.; Zylstra, A. B.; Rinderknecht, H. G.; Sio, H.; Petrasso, R. D.

    2016-05-15

    Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

  1. Laser Beam Propagation through Inertial Confinement Fusion Hohlraum Plasmas

    SciTech Connect

    Froula, D H; Divol, L; Meezan, N B; DIxit, S; Neumayer, P; Moody, J D; Pollock, B B; Ross, J S; Glenzer, S H

    2006-10-26

    A study of the relevant laser-plasma interaction processes has been performed in long-scale length plasmas that emulate the plasma conditions in indirect drive inertial confinement fusion targets. Experiments in this high-temperature (T{sub e} = 3.5 keV), dense (n{sub e} = 0.5 - 1 x 10{sup -3}) hohlraum plasma have demonstrated that blue 351-nm laser beams produce less than 1% total backscatter resulting in transmission greater than 90% for ignition relevant laser intensities (I < 2 x 10{sup 15} W cm{sup -2}). The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows that these results are relevant for the outer beams in ignition hohlraum experiments corresponding to a gain threshold for stimulated Brillouin scattering of 15. By increasing the gas fill density in these experiments further accesses inner beam ignition hohlraum conditions. In this case, stimulated Raman scattering dominates the backscattering processes. They show that scattering is small for gains smaller than 20, which can be achieved through proper choice of the laser beam intensity.

  2. Modeling Hohlraum-Based Laser Plasma Instability Experiments

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.

    2005-10-01

    Laser fusion targets must control laser-plasma instabilities (LPI) in order to perform as designed. We present analyses of recent hohlraum LPI experiments from the Omega laser facility. The targets, gold hohlraums filled with gas or SiO2 foam, are preheated by several 3φ beams before an interaction beam (2φ or 3φ) is fired along the hohlraum axis. The experiments are simulated in 2-D and 3-D using the code hydra. The choice of electron thermal conduction model in hydra strongly affects the simulated plasma conditions. This work is part of a larger effort to systematically explore the usefulness of linear gain as a design tool for fusion targets. We find that the measured Raman and Brillouin backscatter scale monotonically with the peak linear gain calculated for the target; however, linear gain is not sufficient to explain all trends in the data. 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.

  3. Modeling laser-plasma interactions in NIF vacuum hohlraums

    NASA Astrophysics Data System (ADS)

    Williams, E. A.; Hinkel, D. E.; Still, C. H.; Langdon, A. B.; Olson, R. E.; Kline, J.

    2009-11-01

    In preparation for the NIF ignition campaign, a series of experiments are underway firing 96 and 192 beams of the NIF laser into empty gold hohlraums. The primary purpose of these experiments is to qualify the DANTE filtered x-ray diode radiation temerature diagnostic. We plan to have backscatter diagnostics available, giving us an opportunity to test our LPI modeling on the NIF scale. In addition to scaling with energy, we test the use of a gold-boron coating on the hohlraum wall to reduce SBS via increased ion Landau damping of the ion-acoustic waves. We use Lasnex to simulate the hydrodynamic evolution of the hohlraum plasma. Steady state gains were computed using our diagnostic NEWLIP. These were used to suggest appropriate backscatter simulations to be performed with pF3D, a massivel parallel code that couples paraxial light propagation with fluid models of the stimulated plasma ansd ion waves evolving on a background plasma. We describe the results of these simulations, pre- and post-shot, and compare them with experimental results.

  4. Enthalpy generation from mixing in hohlraum-driven targets

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Milovich, Jose

    2016-10-01

    The increase in enthalpy from the physical mixing of two initially separated materials is analytically estimated and applied to ICF implosions and gas-filled hohlraums. Pressure and temperature gradients across a classical interface are shown to be the origin of enthalpy generation from mixing. The amount of enthalpy generation is estimated to be on the order of 100 Joules for a 10 micron-scale annular mixing layer between the solid deuterium-tritium fuel and the undoped high-density carbon ablator of a NIF-scale implosion. A potential resonance is found between the mixing layer thickness and gravitational (Cs2/ g) and temperature-gradient scale lengths, leading to elevated enthalpy generation. These results suggest that if mixing occurs in current capsule designs for the National Ignition Facility, the ignition margin may be appreciably eroded by the associated enthalpy of mixing. The degree of enthalpy generation from mixing of high- Z hohlraum wall material and low- Z gas fills is estimated to be on the order of 100 kJ or more for recent NIF-scale hohlraum experiments, which is consistent with the inferred missing energy based on observed delays in capsule implosion times. Work performed under the auspices of Lawrence Livermore National Security, LLC (LLNS) under Contract No. DE-AC52-07NA27344.

  5. The near vacuum hohlraum campaign at the NIF: A new approach

    SciTech Connect

    Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G.; and others

    2016-05-15

    The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30×). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30× implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

  6. The near vacuum hohlraum campaign at the NIF: A new approach

    NASA Astrophysics Data System (ADS)

    Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Mackinnon, A. J.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G.; Haan, S.; Izumi, N.; Hatarik, R.; Sterne, P.; Celliers, P.; Ralph, J.; Rygg, R.; Strozzi, D.; Kilkenny, J.; Rosenberg, M.; Rinderknecht, H.; Sio, H.; Gatu-Johnson, M.; Frenje, J.; Petrasso, R.; Zylstra, A.; Town, R.; Hurricane, O.; Nikroo, A.; Edwards, M. J.

    2016-05-01

    The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30×). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30× implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

  7. The near vacuum hohlraum campaign at the NIF: A new approach

    SciTech Connect

    Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Mackinnon, A. J.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G.; Haan, S.; Izumi, N.; Hatarik, R.; Sterne, P.; Celliers, P.; Ralph, J.; Rygg, R.; Strozzi, D.; Kilkenny, J.; Rosenberg, M.; Rinderknecht, H.; Sio, H.; Gatu-Johnson, M.; Frenje, J.; Petrasso, R.; Zylstra, A.; Town, R.; Hurricane, O.; Nikroo, A.; Edwards, M. J.

    2016-05-25

    The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30x). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30x implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

  8. The near vacuum hohlraum campaign at the NIF: A new approach

    SciTech Connect

    Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Mackinnon, A. J.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G.; Haan, S.; Izumi, N.; Hatarik, R.; Sterne, P.; Celliers, P.; Ralph, J.; Rygg, R.; Strozzi, D.; Kilkenny, J.; Rosenberg, M.; Rinderknecht, H.; Sio, H.; Gatu-Johnson, M.; Frenje, J.; Petrasso, R.; Zylstra, A.; Town, R.; Hurricane, O.; Nikroo, A.; Edwards, M. J.

    2016-05-25

    The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30x). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30x implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

  9. The near vacuum hohlraum campaign at the NIF: A new approach

    DOE PAGES

    Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; ...

    2016-05-25

    The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30x). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examinemore » the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30x implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.« less

  10. 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.

  11. Demonstration of Symmetry Control of Infrared Heated Deuterium Layers in Hohlraums

    SciTech Connect

    Koziozieski, B J; London, R A; McEachern, R L; Bittner, D N

    2003-08-22

    Infrared smoothed deuterium ice layers inside capsules have been successfully demonstrated for capsules inside cylindrical hohlraums. Improved characterization methods and infrared illumination enables low mode control in both the axial and azimuthal directions. Experimental results agree well with computer models. Results of these experiments will be used to derive accuracy requirements for an infrared heating system for ice layers in hohlraums on NIF.

  12. Using VISAR to assess the M-band isotropy in hohlraums.

    PubMed

    Lanier, N E; Kline, J L; Morton, J

    2016-11-01

    In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum's actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF's natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. These experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.

  13. Using VISAR to assess the M-band isotropy in hohlraums

    NASA Astrophysics Data System (ADS)

    Lanier, N. E.; Kline, J. L.; Morton, J.

    2016-11-01

    In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum's actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF's natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. These experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.

  14. Near Vacuum Hohlraums, a viable path to ignition; a beginning of an answer

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, Laura; Divol, Laurent; Meezan, Nathan; MacKinnon, Andrew; Ross, Steven; Ma, Tammy; Khan, Shahab; Grim, Gary; Fittinghoff, David; Rinderknecht, Hans; Frenje, Johan; Patrasso, Rich; Knauer, Jim; Kilkenny, Joe

    2014-10-01

    Near Vacuum Hohlraum (NVH) is a high coupling platform that might provide a path to ignition using High Density Carbon (HDC) with 10 ns long pulses. We have investigated in a series of experiments on the National Ignition Facility (NIF), our ability to control the symmetry of the implosion while keeping the highest possible implosion velocity. Keeping control of the symmetry as the hohlraum fills in with ablated gold is the main challenge of this platform. Results from experiments where the laser pulse was gradually increased from 4.5 to 8 ns while the hohlraum size was changed from the standard 5.75 hohlraum to a larger 6.72 hohlraum will be presented. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  15. Demonstration of reduced radiation losses in hohlraums made from cocktail mixtures by measuring increased radiation temperatures

    SciTech Connect

    Jones, O; Schein, J; Rosen, M; Suter, L; Wallace, R; Dewald, E; Glenzer, S; Campbell, K; Gunther, J; Hammel, B; Landen, O; Sores, C; Olson, R; Rochau, G; Wilkens, H; Kaae, J; Kilkenny, J; Nikroo, A; Regan, S; Meyerhoffer, D

    2006-11-03

    We present results from experiments, numerical simulations, and analytic modeling that demonstrate enhanced radiation confinement of hohlraums made from cocktail materials. We summarize the results from several previous planar sample experiments that showed the potential promise of cocktails. We then discuss a series of more recent hohlraum experiments that attempted to demonstrate enhanced radiation confinement. Once we understood the importance of oxygen contamination in increasing the specific heat and wall losses of uranium-based cocktails, we implemented new manufacturing and handling techniques for cocktail hohlraums that led to our demonstration of a significant increase in radiation temperature (up to +7eV at 300 eV) compared to a pure Au hohlraum. This data agrees well with modeling and suggests we can expect an 18% reduction in wall loss (and 10% reduction in laser energy) for the current ignition design by switching to cocktail hohlraums.

  16. Hohlraum fill gas density scaling of x-ray drive, symmetry, and laser coupling backscatter in 6.72-mm NIF hohlraums

    NASA Astrophysics Data System (ADS)

    Jones, Ogden; Izumi, N.; Hopkins, L. B.; Strozzi, D. J.; Amendt, P. A.; Hall, G. N.; Ho, D. D.; Khan, S. F.; Meezan, N. B.; Moody, J. D.; Nagel, S. R.; Ralph, J. E.; Town, R. P. J.

    2014-10-01

    Most ignition experiments carried out on the NIF to date have used hohlraums with helium gas fill at 1--1.6 mg/cc density in order to prevent excessive hohlraum wall motion and help to control drive symmetry. A unique feature of 2-shock high density carbon (HDC) ignition designs is that they require a much shorter (~7 ns) laser pulse than the ~20 ns duration pulses that are typically used for 3-shock or 4-shock CH ablator designs, so there is less time for the wall to move. As a result, it is possible to reduce the hohlraum gas fill density. We have done 2D convergent ablator experiments in a 6.72 mm diameter hohlraum at fill densities of 0.03 and 0.6 mg/cc. These experiments used HDC capsules driven by a 1.5 MJ, 370 TW peak power laser pulse. They demonstrated low backscatter (<4%) and effective drives that are much closer to high flux model predictions than for typical gas-filled hohlraums. The 0.6 mg/cc fill reduced the amount of unabsorbed inner cone power that is reflected out of the hohlraum for the 0.03 mg/cc case. Also, the 0.6 mg/cc has improved symmetry that is in good agreement with modeling. Prepared by LLNL under Contract DE-AC52-07NA27344.

  17. 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%.

  18. A unified free-form representation applied to the shape optimization of the hohlraum with octahedral 6 laser entrance holes

    SciTech Connect

    Jiang, Shaoen; Ding, Yongkun; Huang, Yunbao E-mail: scmyking-2008@163.com; Li, Haiyan; Jing, Longfei E-mail: scmyking-2008@163.com; Huang, Tianxuan

    2016-01-15

    The hohlraum is very crucial for indirect laser driven Inertial Confinement Fusion. Usually, its shape is designed as sphere, cylinder, or rugby with some kind of fixed functions, such as ellipse or parabola. Recently, a spherical hohlraum with octahedral 6 laser entrance holes (LEHs) has been presented with high flux symmetry [Lan et al., Phys. Plasmas 21, 010704 (2014); 21, 052704 (2014)]. However, there is only one shape parameter, i.e., the hohlraum to capsule radius ratio, being optimized. In this paper, we build the hohlraum with octahedral 6LEHs with a unified free-form representation, in which, by varying additional shape parameters: (1) available hohlraum shapes can be uniformly and accurately represented, (2) it can be used to understand why the spherical hohlraum has higher flux symmetry, (3) it allows us to obtain a feasible shape design field satisfying flux symmetry constraints, and (4) a synthetically optimized hohlraum can be obtained with a tradeoff of flux symmetry and other hohlraum performance. Finally, the hohlraum with octahedral 6LEHs is modeled, analyzed, and then optimized based on the unified free-form representation. The results show that a feasible shape design field with flux asymmetry no more than 1% can be obtained, and over the feasible design field, the spherical hohlraum is validated to have the highest flux symmetry, and a synthetically optimal hohlraum can be found with closing flux symmetry but larger volume between laser spots and centrally located capsule.

  19. A unified free-form representation applied to the shape optimization of the hohlraum with octahedral 6 laser entrance holes

    NASA Astrophysics Data System (ADS)

    Jiang, Shaoen; Huang, Yunbao; Jing, Longfei; Li, Haiyan; Huang, Tianxuan; Ding, Yongkun

    2016-01-01

    The hohlraum is very crucial for indirect laser driven Inertial Confinement Fusion. Usually, its shape is designed as sphere, cylinder, or rugby with some kind of fixed functions, such as ellipse or parabola. Recently, a spherical hohlraum with octahedral 6 laser entrance holes (LEHs) has been presented with high flux symmetry [Lan et al., Phys. Plasmas 21, 010704 (2014); 21, 052704 (2014)]. However, there is only one shape parameter, i.e., the hohlraum to capsule radius ratio, being optimized. In this paper, we build the hohlraum with octahedral 6LEHs with a unified free-form representation, in which, by varying additional shape parameters: (1) available hohlraum shapes can be uniformly and accurately represented, (2) it can be used to understand why the spherical hohlraum has higher flux symmetry, (3) it allows us to obtain a feasible shape design field satisfying flux symmetry constraints, and (4) a synthetically optimized hohlraum can be obtained with a tradeoff of flux symmetry and other hohlraum performance. Finally, the hohlraum with octahedral 6LEHs is modeled, analyzed, and then optimized based on the unified free-form representation. The results show that a feasible shape design field with flux asymmetry no more than 1% can be obtained, and over the feasible design field, the spherical hohlraum is validated to have the highest flux symmetry, and a synthetically optimal hohlraum can be found with closing flux symmetry but larger volume between laser spots and centrally located capsule.

  20. FABRICATION OF WINDOW SADDLES FOR NIF CRYOGENIC HOHLRAUMS

    SciTech Connect

    GIRALDEZ,E; KAAE,J.L

    2003-06-01

    OAK-B135 A planar diagnostic viewing port attached to the cylindrical wall of the NIF cryogenic hohlraum requires a saddle-like transition piece. While the basic design of this window saddle is straightforward, its fabrication is not, given the scale and precision of the component. They solved the problem through the use of a two segment copper mandrel to electroform the gold window saddle. The segments were micro-machined using a combination of single-point diamond turning and single point diamond milling. These processes as well as the electroplating conditions, final machining and mandrel removal are described in this paper.

  1. Fabrication of Window Saddles for NIF Cryogenic Hohlraums

    SciTech Connect

    Giraldez, Emilio; Kaae, James L.

    2004-03-15

    A planar diagnostic viewing port attached to the cylindrical wall of the NIF cryogenic hohlraum requires a saddle-like transition piece. While the basic design of this window saddle is straightforward, its fabrication is not, given the scale and precision of the component. We solved the problem through the use of a two segment copper mandrel to electroform the gold window saddle. The segments were micro-machined using a combination of single-point diamond turning and single point diamond milling. These processes as well as the electroplating conditions, final machining and mandrel removal are described in this pap0008.

  2. Rugby-like hohlraum experimental designs for demonstrating x-ray drive enhancement

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Cerjan, C.; Hinkel, D. E.; Milovich, J. L.; Park, H.-S.; Robey, H. F.

    2008-01-01

    A suite of experimental designs for the Omega laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)] using rugby and cylindrical hohlraums is proposed to confirm the energetics benefits of rugby-shaped hohlraums over cylinders under optimal implosion symmetry conditions. Postprocessed Dante x-ray drive measurements predict a 12-17eV (23%-36%) peak hohlraum temperature (x-ray flux) enhancement for a 1ns flattop laser drive history. Simulated core self-emission x-ray histories also show earlier implosion times by 200-400ps, depending on the hohlraum case-to-capsule ratio and laser-entrance-hole size. Capsules filled with 10 or 50atm of deuterium (DD) are predicted to give in excess of 1010 neutrons in two-dimensional hohlraum simulations in the absence of mix, enabling DD burn history measurements for the first time in indirect-drive on Omega. Capsule designs with 50atm of DHe3 are also proposed to make use of proton slowing for independently verifying the drive benefits of rugby hohlraums. Scale-5/4 hohlraum designs are also introduced to provide further margin to potential laser-plasma-induced backscatter and hot-electron production.

  3. The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Hall, G. N.; Jones, O. S.; Strozzi, D. J.; Moody, J. D.; Turnbull, D.; Ralph, J.; Michel, P. A.; Hohenberger, M.; Moore, A. S.; Landen, O. L.; Divol, L.; Bradley, D. K.; Hinkel, D. E.; Mackinnon, A. J.; Town, R. P. J.; Meezan, N. B.; Berzak Hopkins, L.; Izumi, N.

    2017-05-01

    Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Measurements characterized the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρgf between 0.03 mg/cc ("near vacuum") and 1.6 mg/cc. For hohlraums with ρgf up to 0.85 mg/cc, very little stimulated Raman backscatter (SRS) was observed. For higher ρgf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρgf ≥ 0.6 mg/cc once the laser reached peak power. However, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ˜10% higher than the gas filled hohlraums throughout the main pulse.

  4. The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

    DOE PAGES

    Hall, G. N.; Jones, O. S.; Strozzi, D. J.; ...

    2017-05-11

    Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Our ,easurements characterize the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρgf between 0.03 mg/cc (“near vacuum”) and 1.6 mg/cc. For hohlraums with ρgf up to 0.85 mg/cc, very little stimulated Raman backscatter (SRS) wasmore » observed. Furthermore, for higher ρgf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρgf ≥ 0.6 mg/cc once the laser reached peak power. But, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ~10% higher than the gas filled hohlraums throughout the main pulse.« less

  5. Investigating the hohlraum radiation properties through the angular distribution of the radiation temperature

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Zhang, Huasen; Song, Peng; Zou, Shiyang; Zhu, Shaoping; Li, Sanwei; Li, Zhichao; Guo, Liang; Jiang, Shaoen; Ding, Yongkun

    2016-10-01

    The symmetric radiation drive is essential to the capsule implosion in the indirect drive fusion, but is hard to achieve due to the non-uniform radiation distribution inside the hohlraum. The non-uniform radiation properties of both vacuum and gas-filled hohlraums are studied by investigating the angular distribution of the radiation temperature. The non-uniform radiation distribution inside the hohlraum induces the variation of the radiation temperature between different view angles. The simulations show that both the angular distribution of the radiation temperature and the hohlraum radiation distribution can be affected by the electron heat flux. Comparisons between the experiments and simulations further indicate that the x-ray emission of the blow-off plasma is overestimated in the simulations when it stagnates around the hohlraum axis. The axial position of the laser spot can also be estimated by the angular distribution of the radiation temperature due to their sensitive dependence. The inferred laser spot moves closer to the laser entrance hole in the gas-filled hohlraum than that in the vacuum hohlraum, consisting with the x-ray images taken from the framing camera.

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

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N. B.; Mackinnon, A. J.; Ho, D. D.; Jones, O. S.; Khan, S.; Milovich, J. L.; Ross, J. S.; Amendt, P.; Casey, D.; Celliers, P. M.; Pak, A.; Peterson, J. L.; Ralph, J.; Rygg, J. R.

    2015-05-01

    Recent experiments at the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] have explored driving high-density carbon ablators with near-vacuum hohlraums, which use a minimal amount of helium gas fill. These hohlraums show improved efficiency relative to conventional gas-filled hohlraums in terms of minimal backscatter, minimal generation of suprathermal electrons, and increased hohlraum-capsule coupling. Given these advantages, near-vacuum hohlraums are a promising choice for pursuing high neutron yield implosions. Long pulse symmetry control, though, remains a challenge, as the hohlraum volume fills with material. Two mitigation methodologies have been explored, dynamic beam phasing and increased case-to-capsule ratio (larger hohlraum size relative to capsule). Unexpectedly, experiments have demonstrated that the inner laser beam propagation is better than predicted by nominal simulations, and an enhanced beam propagation model is required to match measured hot spot symmetry. Ongoing work is focused on developing a physical model which captures this enhanced propagation and on utilizing the enhanced propagation to drive longer laser pulses than originally predicted in order to reach alpha-heating dominated neutron yields.

  7. Cylindrical target Li-beam-driven hohlraum experiments

    SciTech Connect

    Derzon, M.S.; Aubert, J.; Chandler, G.A.

    1998-06-01

    The authors performed a series of experiments on the Particle Beam Fusion Accelerator II (PBFA II) in May, 1994, and obtained a brightness temperature of 61 {+-} 2 eV for an ion-beam heated hohlraum. The hohlraum was a 4-mm-diameter, right-circular cylinder with a 1.5-mm-thick gold wall, a low-density CH foam fill, and a 1.5- or 3-mm-diameter diagnostic aperture in the top. The nominal parameters of the radially-incident PBFA II Li ion beam were 9 MeV peak energy ({approximately}10 MeV at the gas cell) at the target at a peak power of 2.5 {+-} 0.3 TW/cm{sup 2} and a 15 ns pulse width. Azimuthal variations in intensity of a factor of 3, with respect to the mean, were observed. Nonuniformities in thermal x-ray emission across the area of the diagnostic hole were also observed. Time-dependent hole-closure velocities were measured: the time-averaged velocity of {approximately}2 cm/{micro}s is in good agreement with sound speed estimates. Unfolded x-ray spectra and brightness temperatures as a function of time are reported and compared to simulations. Hole closure corrections are discussed with comparisons between XRD and bolometer measurements. Temperature scaling with power on target is also presented.

  8. Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums.

    PubMed

    Glenzer, S H; MacGowan, B J; Meezan, N B; Adams, P A; Alfonso, J B; Alger, E T; Alherz, Z; Alvarez, L F; Alvarez, S S; Amick, P V; Andersson, K S; Andrews, S D; Antonini, G J; Arnold, P A; Atkinson, D P; Auyang, L; Azevedo, S G; Balaoing, B N M; Baltz, J A; Barbosa, F; Bardsley, G W; Barker, D A; Barnes, A I; Baron, A; Beeler, R G; Beeman, B V; Belk, L R; Bell, J C; Bell, P M; Berger, R L; Bergonia, M A; Bernardez, L J; Berzins, L V; Bettenhausen, R C; Bezerides, L; Bhandarkar, S D; Bishop, C L; Bond, E J; Bopp, D R; Borgman, J A; Bower, J R; Bowers, G A; Bowers, M W; Boyle, D T; Bradley, D K; Bragg, J L; Braucht, J; Brinkerhoff, D L; Browning, D F; Brunton, G K; Burkhart, S C; Burns, S R; Burns, K E; Burr, B; Burrows, L M; Butlin, R K; Cahayag, N J; Callahan, D A; Cardinale, P S; Carey, R W; Carlson, J W; Casey, A D; Castro, C; Celeste, J R; Chakicherla, A Y; Chambers, F W; Chan, C; Chandrasekaran, H; Chang, C; Chapman, R F; Charron, K; Chen, Y; Christensen, M J; Churby, A J; Clancy, T J; Cline, B D; Clowdus, L C; Cocherell, D G; Coffield, F E; Cohen, S J; Costa, R L; Cox, J R; Curnow, G M; Dailey, M J; Danforth, P M; Darbee, R; Datte, P S; Davis, J A; Deis, G A; Demaret, R D; Dewald, E L; Di Nicola, P; Di Nicola, J M; Divol, L; Dixit, S; Dobson, D B; Doppner, T; Driscoll, J D; Dugorepec, J; Duncan, J J; Dupuy, P C; Dzenitis, E G; Eckart, M J; Edson, S L; Edwards, G J; Edwards, M J; Edwards, O D; Edwards, P W; Ellefson, J C; Ellerbee, C H; Erbert, G V; Estes, C M; Fabyan, W J; Fallejo, R N; Fedorov, M; Felker, B; Fink, J T; Finney, M D; Finnie, L F; Fischer, M J; Fisher, J M; Fishler, B T; Florio, J W; Forsman, A; Foxworthy, C B; Franks, R M; Frazier, T; Frieder, G; Fung, T; Gawinski, G N; Gibson, C R; Giraldez, E; Glenn, S M; Golick, B P; Gonzales, H; Gonzales, S A; Gonzalez, M J; Griffin, K L; Grippen, J; Gross, S M; Gschweng, P H; Gururangan, G; Gu, K; Haan, S W; Hahn, S R; Haid, B J; Hamblen, J E; Hammel, B A; Hamza, A V; Hardy, D L; Hart, D R; Hartley, R G; Haynam, C A; Heestand, G M; Hermann, M R; Hermes, G L; Hey, D S; Hibbard, R L; Hicks, D G; Hinkel, D E; Hipple, D L; Hitchcock, J D; Hodtwalker, D L; Holder, J P; Hollis, J D; Holtmeier, G M; Huber, S R; Huey, A W; Hulsey, D N; Hunter, S L; Huppler, T R; Hutton, M S; Izumi, N; Jackson, J L; Jackson, M A; Jancaitis, K S; Jedlovec, D R; Johnson, B; Johnson, M C; Johnson, T; Johnston, M P; Jones, O S; Kalantar, D H; Kamperschroer, J H; Kauffman, R L; Keating, G A; Kegelmeyer, L M; Kenitzer, S L; Kimbrough, J R; King, K; Kirkwood, R K; Klingmann, J L; Knittel, K M; Kohut, T R; Koka, K G; Kramer, S W; Krammen, J E; Krauter, K G; Krauter, G W; Krieger, E K; Kroll, J J; La Fortune, K N; Lagin, L J; Lakamsani, V K; Landen, O L; Lane, S W; Langdon, A B; Langer, S H; Lao, N; Larson, D W; Latray, D; Lau, G T; Le Pape, S; Lechleiter, B L; Lee, Y; Lee, T L; Li, J; Liebman, J A; Lindl, J D; Locke, S F; Loey, H K; London, R A; Lopez, F J; Lord, D M; Lowe-Webb, R R; Lown, J G; Ludwigsen, A P; Lum, N W; Lyons, R R; Ma, T; MacKinnon, A J; Magat, M D; Maloy, D T; Malsbury, T N; Markham, G; Marquez, R M; Marsh, A A; Marshall, C D; Marshall, S R; Maslennikov, I L; Mathisen, D G; Mauger, G J; Mauvais, M -Y; McBride, J A; McCarville, T; McCloud, J B; McGrew, A; McHale, B; MacPhee, A G; Meeker, J F; Merill, J S; Mertens, E P; Michel, P A; Miller, M G; Mills, T; Milovich, J L; Miramontes, R; Montesanti, R C; Montoya, M M; Moody, J; Moody, J D; Moreno, K A; Morris, J; Morriston, K M; Nelson, J R; Neto, M; Neumann, J D; Ng, E; Ngo, Q M; Olejniczak, B L; Olson, R E; Orsi, N L; Owens, M W; Padilla, E H; Pannell, T M; Parham, T G; Patterson, R W; Pavel, G; Prasad, R R; Pendlton, D; Penko, F A; Pepmeier, B L; Petersen, D E; Phillips, T W; Pigg, D; Piston, K W; Pletcher, K D; Powell, C L; Radousky, H B; Raimondi, B S; Ralph, J E; Rampke, R L; Reed, R K; Reid, W A; Rekow, V V; Reynolds, J L; Rhodes, J J; Richardson, M J; Rinnert, R J; Riordan, B P; Rivenes, A S; Rivera, A T; Roberts, C J; Robinson, J A; Robinson, R B; Robison, S R; Rodriguez, O R; Rogers, S P; Rosen, M D; Ross, G F; Runkel, M; Runtal, A S; Sacks, R A; Sailors, S F; Salmon, J T; Salmonson, J D; Saunders, R L; Schaffer, J R; Schindler, T M; Schmitt, M J; Schneider, M B; Segraves, K S; Shaw, M J; Sheldrick, M E; Shelton, R T; Shiflett, M K; Shiromizu, S J; Shor, M; Silva, L L; Silva, S A; Skulina, K M; Smauley, D A; Smith, B E; Smith, L K; Solomon, A L; Sommer, S; Soto, J G; Spafford, N I; Speck, D E; Springer, P T; Stadermann, M; Stanley, F; Stone, T G; Stout, E A; Stratton, P L; Strausser, R J; Suter, L J; Sweet, W; Swisher, M F; Tappero, J D; Tassano, J B; Taylor, J S; Tekle, E A; Thai, C; Thomas, C A; Thomas, A; Throop, A L; Tietbohl, G L; Tillman, J M; Town, R P J; Townsend, S L; Tribbey, K L; Trummer, D; Truong, J; Vaher, J; Valadez, M; Van Arsdall, P; Van Prooyen, A J; Vergel de Dios, E O; Vergino, M D; Vernon, S P; Vickers, J L; Villanueva, G T; Vitalich, M A; Vonhof, S A; Wade, F E; Wallace, R J; Warren, C T; Warrick, A L; Watkins, J; Weaver, S; Wegner, P J; Weingart, M A; Wen, J; White, K S; Whitman, P K; Widmann, K; Widmayer, C C; Wilhelmsen, K; Williams, E A; Williams, W H; Willis, L; Wilson, E F; Wilson, B A; Witte, M C; Work, K; Yang, P S; Young, B K; Youngblood, K P; Zacharias, R A; Zaleski, T; Zapata, P G; Zhang, H; Zielinski, J S; Kline, J L; Kyrala, G A; Niemann, C; Kilkenny, J D; Nikroo, A; Van Wonterghem, B M; Atherton, L J; Moses, E I

    2011-02-25

    We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

  9. Stauts of the Laser Inertial Fusion Energy (LIFE) Hohlraum Point Design

    SciTech Connect

    Amendt, P; Dunne, M; Ho, D; Lasinski, B; Meeker, D; Ross, J S

    2012-04-10

    Progress on the hohlraum point design for the LIFE engine is described. New features in the original design [Amendt et al., Fus. Sci. Technol. 60, 49 (2011)] are incorporated that address the imperatives of low target cost, high manufacturing throughput, efficient and prompt material recycling, an ability for near-term testing of key target design uncertainties on the National Ignition Facility, and robustness to target chamber environment and injection insults. To this end, the novel use of Pb hohlraums and aerogel-supported liquid DT fuel loading within a high-density-carbon (HDC) ablator is implemented in the hohlraum point design.

  10. Laser beam smoothing and backscatter saturation processes in plasmas relevant to National Ignition Facility hohlraums

    SciTech Connect

    Berger, R L; Cohen, B I; Decker, C D; Dixit, S; Glenzer, S H; Hinkel, D E; Kirkwood, R K; Langdon, A B; Lefebvre, E; MacGowan, B J; Moody, J D; Rothenberg, J E; Rousseuax, C; Still, C H; Suter, L J; Williams, E A

    1998-10-01

    We have used gas-filled targets irradiated at the Nova laser to simulate National Ignition Facility (NlF) hohlraum plasmas and to study the dependence of Stimulated Raman (SRS) and Brillouin (SBS) Scattering on beam smoothing at a range of laser intensities (3{omega}, 2 - 4 10{sup 15}Wcm{sup -2}) and plasma conditions. We have demonstrated the effectiveness of polarization smoothing as a potential upgrade to the NIF. Experiments with higher intensities and higher densities characteristic of 350eV hohlraum designs indicate that with appropriate beam smoothing the backscatter from such hohlraums may be tolerable.

  11. Hard X-ray and Hot Electron Environment in Vacuum Hohlraums at NIF

    SciTech Connect

    McDonald, J W; . Suter, L J; Landen, O L; Foster, J M; Celeste, J R; Holder, J P; Dewald, E L; Schneider, M B; Hinkel, D E; Kauffman, R L; Atherton, L J; Bonanno, R E; Dixit, S N; Eder, D C; Haynam, C A; Kalantar, D H; Koniges, A E; Lee, F D; MacGowan, B J; Manes, K R; Munro, D H; Murray, J R; Shaw, M J; Stevenson, R M; Parham, T G; Van Wonterghem, B M; Wallace, R J; Wegner, P J; Whitman, P K; Young, B K; Hammel, B A; Moses, E I

    2005-09-22

    Time resolved hard x-ray images (hv > 9 keV) and time integrated hard x-ray spectra (hv = 18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength NIF laser beams are presented as a function of hohlraum size and laser power and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (f{sub hot}) and a comparison to a filling model are presented.

  12. Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

    PubMed

    Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

    2008-02-01

    We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

  13. Green (2(omega)) Laser Beam propagation in high-temperature Hohlraum Plasmas

    SciTech Connect

    Niemann, C; Berger, R; Divol, L; Froula, D H; Jones, O S; Kirkwood, R K; Meezan, N; Moody, J; Ross, J S; Suter, L; Glenzer, S H

    2007-10-26

    We demonstrate propagation and small backscatter losses of a frequency-doubled (2{omega}) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of two higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2{omega} laser beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggests that good laser coupling into fusion hohlraums using 2{omega} light is possible.

  14. Capsule implosions driven by dynamic hohlraum x-rays

    NASA Astrophysics Data System (ADS)

    Bailey, James

    2005-10-01

    Dynamic hohlraum experiments at the Z facility already implode capsules with up to 80 kJ absorbed x-ray energy. However, many challenging issues remain for ICF. The present experiments use diagnostic capsules to address two of these issues: symmetry measurement and control and building understanding of the capsule/hohlraum implosion system. A suite of x-ray spectrometers record time and space resolved spectra emitted by Ar tracer atoms in the implosion core, simultaneously from up to three different quasi-orthogonal directions. Comparing the results with simulation predictions provide severe tests of understanding. These data also can used to produce a tomographic reconstruction of the time resolved core temperature and density profiles. X-ray and neutron diagnostics are used to examine how the implosion conditions change as the capsule design changes. The capsule design changes include variations in CH wall thickness and diameter, Ge-doped CH shells, and SiO2 shells. In addition, a new campaign investigating Be capsule implosions is beginning. Be capsules may offer superior performance for dynamic hohlraum research and it may be possible to investigate NIF-relevant Be implosion issues such as the fill tube effects, sensitivity to columnar growth associated with sputtered Be capsule fabrication, and the effect of Cu dopants on implosion conditions. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Dept. of Energy under contract No. DE-AC04-94AL85000. * In collaboration with G.A. Rochau, G.A. Chandler, S.A. Slutz, P.W. Lake, G. Cooper, G.S. Dunham, R.J. Leeper, R. Lemke, T.A. Mehlhorn, T.J. Nash, D.S. Nielsen, K. Peterson, C.L. Ruiz, D.B. Sinars, J. Torres, W. Varnum, Sandia; R.C. Mancini, T.J. Buris-Mog, UNR; I. Golovkin, J.J. MacFarlane, PRISM; A. Nikro, D. Steinman, J.D. Kilkenny, H. Xu, General Atomics; M. Bump, T.C. Moore, K-tech; D.G. Schroen, Schafer

  15. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    SciTech Connect

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Kline, J. L.; MacDonald, M. J.; Sefkow, A. B.; Yin, L.; Betti, R.

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled using the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.

  16. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    SciTech Connect

    Montgomery, D. S. Albright, B. J.; Kline, J. L.; Yin, L.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.; MacDonald, M. J.; Sefkow, A. B.

    2015-01-15

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with B{sub z} ≤ 7.5-T. We found that an external field B{sub z} = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. The experiments were modeled using the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.

  17. Design of laser hohlraum conditions to drive polycrystalline matrial instability experiments

    NASA Astrophysics Data System (ADS)

    Tubbs, David; Kindel, Joseph; Hoffman, Nelson

    2002-11-01

    A companion presentation to this conference (N. M. Hoffman, et al., Radiative shocking and acceleration of polycrystalline slabs ...) discusses the motivation and theoretical x-radiation drive conditions for the empirical assessment of grain structure in ablatively accelerated beryllium slabs. We present a design methodology to determine laser pulse shape and hohlraum geometry, for the OMEGA laser facility, that yield the necessary x-radiation conditions on target. We assess simulations of the standard hohlraum (1600 micron cylindrical diameter, 1200 micron length, 1200 micron diameter LEH, and 25 micron gold-wall thickness) against available data from OMEGA, and we consider alternative hohlraum geometries. We summarize the most plausible laser hohlraum conditions, achievable at OMEGA, that result from our initial design study.

  18. Experimental Demonstration of X-Ray Drive Enhancement with Rugby-Shaped Hohlraums

    NASA Astrophysics Data System (ADS)

    Philippe, F.; Casner, A.; Caillaud, T.; Landoas, O.; Monteil, M. C.; Liberatore, S.; Park, H. S.; Amendt, P.; Robey, H.; Sorce, C.; Li, C. K.; Seguin, F.; Rosenberg, M.; Petrasso, R.; Glebov, V.; Stoeckl, C.

    2010-01-01

    Rugby-shaped hohlraums have been suggested as a way to enhance x-ray drive in the indirect drive approach to inertial confinement fusion. This Letter presents an experimental comparison of rugby-shaped and cylinder hohlraums used for D2 and DHe3-filled capsules implosions on the Omega laser facility, demonstrating an increase of x-ray flux by 18% in rugby-shaped hohlraums. The highest yields to date for deuterium gas implosions in indirect drive on Omega (1.5×1010 neutrons) were obtained, allowing for the first time the measurement of a DD burn history. Proton spectra measurements provide additional validation of the higher drive in rugby-shaped hohlraums.

  19. What measurements of proton self emission tell us about hohlraum fields and yield anomalies

    NASA Astrophysics Data System (ADS)

    Petrasso, R.; Li, C.; Seguin, F.; Frenje, J.; Rosenberg, M.; Rinderknecht, H.; Philippe, F.; Casner, A.; Caillaud, T.; Landoas, O.; Bourgade, J.-L.; Amendt, P.; Izumi, N.; Koch, J.; Landen, O.; Milovich, J.; Park, H.; Robey, H.; Robey, R.; Town, R.; Nikroo, A.; Kilkenny, J.

    2009-11-01

    Measurements have been made of 14.7-MeV self-emission protons, from reactions of D-3He fuel, for a variety of hohlraums - scale 1 and scale .5ex3 -.1em/ -.15em.25ex3 , gold and cocktail hohlraums, vacuum and gas-filled hohlraums, cylindrical and rugby geometries, drive with and without phase plates, drive with different numbers of beams, and implosions with different capsule parameters. The picture that emerges is quite consistent: large anisotropies in the proton fluence pattern are generally observed out the LEH but little if any variations through the hohlraum equator. In addition, we examine whether the scaling of yields from pure D2 to D-3He mixtures is found to deviate from the expected density scaling (i.e. the Rygg Effect), as reported recently for directly driven capsules (1). (1) H. Herrmann et al., PoP 16, 056312(2009)

  20. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    DOE PAGES

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; ...

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled usingmore » the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.« less

  1. Effect of NLTE Emissivity Models on NIF Ignition Hohlraum Power Requirements

    SciTech Connect

    Suter, L.; Rosen, M.; Springer, P.; Haan, S.; Hansen, S.

    2009-09-10

    NLTE atomic physics model can significantly affect the power requirements and plasma conditions in ignition hohlraums. This is because the emissivity is a significant factor in determining the time dependent coronal temperature of the hot blow-off plasma filling ignition hohlraums, which, in turn, determines the total energy stored in that coronal plasma at any instant. Here we present best estimates of NLTE emissivity using the SCRAM model, including the range of uncertainty, and compare them with the emissivity of the model used to design NIF ignition hohlraums and set the NIF pulse shape, XSN NLTE. We then present pulse shapes derived from hohlraum simulations using an atomic physics model that approximates the SCRAM emissivities. We discuss the differences in coronal energetics and show how this affects the pulse shape and, in particular, the peak power requirement.

  2. A simple model for a shock wave in a dynamic hohlraum

    NASA Astrophysics Data System (ADS)

    Xu, Qiang; Zhou, Shao-tong; Ren, Xiao-dong; Wang, Kun-lun; Huang, Xian-bin

    2017-02-01

    The dynamic hohlraum (DH) is an approach to Inertial Confinement Fusion, and its X-ray radiation can be widely used in high energy density physics. The shock wave in dynamic hohlraum is important because it heats the foam to high radiation temperatures. Here, we proposed a simple model to describe the shock wave in the dynamic hohlraum. Based on the Rocket ablation model, this simple shock model connects the wire-array implosion phase and the shock formation phase. We also use the experimental result of dynamic hohlraum with a heavy foam mass acquired on primary test stand to verify this model. This simple shock model helps researchers to estimate when and where the collision happens so that researchers could understand the physics in DH more clearly.

  3. Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility

    SciTech Connect

    McDonald, J.W.; Suter, L.J.; Landen, O.L.; Foster, J.M.; Celeste, J.R.; Holder, J.P.; Dewald, E.L.; Schneider, M.B.; Hinkel, D.E.; Kauffman, R.L.; Atherton, L.J.; Bonanno, R.E.; Dixit, S.N.; Eder, D.C.; Haynam, C.A.; Kalantar, D.H.; Koniges, A.E.; Lee, F.D.; MacGowan, B.J.; Manes, K.R.

    2006-03-15

    Time resolved hard x-ray images (hv>9 keV) and time integrated hard x-ray spectra (hv=18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] laser beams are presented as a function of hohlraum size, laser power, and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (F{sub hot}) shows a correlation with laser intensity and with an empirical hohlraum plasma filling model. In addition, the significance of Au K-alpha emission and Au K-shell reabsorption observed in some of the bremsstrahlung dominated spectra is discussed.

  4. Characterizing Hohlraum Plasma Conditions at the National Ignition Facility (NIF) Using X-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Barrios, Maria Alejandra

    2015-11-01

    Improved hohlraums will have a significant impact on increasing the likelihood of indirect drive ignition at the NIF. In indirect-drive Inertial Confinement Fusion (ICF), a high-Z hohlraum converts laser power into a tailored x-ray flux that drives the implosion of a spherical capsule filled with D-T fuel. The x-radiation drive to capsule coupling sets the velocity, adiabat, and symmetry of the implosion. Previous experiments in gas-filled hohlraums determined that the laser-hohlraum energy coupling is 20-25% less than modeled, therefore identifying energy loss mechanisms that reduce the efficacy of the hohlraum drive is central to improving implosion performance. Characterizing the plasma conditions, particularly the plasma electron temperature (Te) , is critical to understanding mechanism that affect the energy coupling such as the laser plasma interactions (LPI), hohlraum x-ray conversion efficiency, and dynamic drive symmetry. The first Te measurements inside a NIF hohlraum, presented here, were achieved using K-shell X-ray spectroscopy of an Mn-Co tracer dot. The dot is deposited on a thin-walled CH capsule, centered on the hohlraum symmetry axis below the laser entrance hole (LEH) of a bottom-truncated hohlraum. The hohlraum x-ray drive ablates the dot and causes it to flow upward, towards the LEH, entering the hot laser deposition region. An absolutely calibrated streaked spectrometer with a line of sight into the LEH records the temporal history of the Mn and Co X-ray emission. The measured (interstage) Lyα/ Heα line ratios for Co and Mn and the Mn-Heα/Co-Heα isoelectronic line ratio are used to infer the local plasma Te from the atomic physics code SCRAM. Time resovled x-ray images perpendicular to the hohlraum axis record the dot expansion and trajectory into the LEH region. The temporal evolution of the measured Te and dot trajectory are compared with simulations from radiation-hydrodynamic codes. This work was performed under the auspices of the U

  5. 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.

  6. Hot electron measurements in ignition relevant Hohlraums on the National Ignition Facility.

    PubMed

    Dewald, E L; Thomas, C; Hunter, S; Divol, L; Meezan, N; Glenzer, S H; Suter, L J; Bond, E; Kline, J L; Celeste, J; Bradley, D; Bell, P; Kauffman, R L; Kilkenny, J; Landen, O L

    2010-10-01

    On the National Ignition Facility (NIF), hot electrons generated in laser heated Hohlraums are inferred from the >20 keV bremsstrahlung emission measured with the time integrated FFLEX broadband spectrometer. New high energy (>200 keV) time resolved channels were added to infer the generated >170 keV hot electrons that can cause ignition capsule preheat. First hot electron measurements in near ignition scaled Hohlraums heated by 96-192 NIF laser beams are presented.

  7. Experimental results and modeling of a dynamic hohlraum on SATURN

    SciTech Connect

    Derzon, M.S.; Allshouse, G.O.; Deeney, C.; Leeper, R.J.; Nash, T.J.; Matuska, W.; Peterson, D.L.; MacFarlane, J.J.; Ryutov, D.D.

    1998-06-01

    Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--135 eV Planckian before the target shock heated, or stagnated, on-axis. Peak pinch radiation temperatures of nominally 160 eV were obtained. Measured early time x-ray emission histories and temperature estimates agree well with modeled performance in the 200--280 eV band using a 2D radiation magneto-hydrodynamics code. However, significant differences are observed in comparisons of the x-ray images and 2D simulations.

  8. Soft x-ray images of the Laser Entrance Hole of NIC Hohlraums (paper, HTPD2012)

    SciTech Connect

    Schneider, M B; Meezan, N B

    2012-04-30

    Hohlraums at the National Ignition Facility convert laser energy into a thermal x-radiation drive, which implodes the capsule, thus compressing the fuel. The x-radiation drive is measured with a low resolution, time-resolved x-ray spectrometer that views the hohlraum's laser entrance hole (LEH) at 37{sup o} to the hohlraum axis. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the area and fraction of the measured x-radiation which comes from the region inside the hohlraum must be known. The size of the LEH is measured with the time integrated Static X-ray Imager (SXI) which view the LEH at 18{sup o} to the hohlraum axis. A soft x-ray image has been added to the SXI to measure the fraction of x-radiation inside the LEH's Clear Aperture in order to correct the measured radiation. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the x-ray energy peak of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.

  9. Correspondence between laser coupling and x-ray flux measurements in a NIF hohlraum

    NASA Astrophysics Data System (ADS)

    Moody, J. D.; Divol, L.; Landen, O.; Lepape, S.; Michel, P.; Ralph, J.; Town, R. P. J.; Widmann, K.; Moore, A.

    2014-10-01

    We describe a simple model relating measurements of the hohlraum x-ray emission (DANTE) to the coupled (incident less backscattered) laser power in NIF indirect drive hohlraum experiments. The model was motivated by observing that the measured x-ray emission showed a lag in rise corresponding to a measured reduction in laser coupling due to backscatter. Two adjustable scalar parameters (a coupling efficiency and a time-scale) in the model are determined for each experiment. Comparing these parameters for different hohlraum gas-fill, ablator, pulse-length, and laser power conditions provides insight into the hohlraum behavior and performance. In some cases, the model can be inverted to estimate the backscatter loss using the measured hohlraum x-ray emission time-history and delivered laser power. We will describe the model and compare the adjustable parameters between different hohlraum platforms. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  10. Radiation characteristics and implosion dynamics of Z-pinch dynamic hohlraums performed on PTS facility

    NASA Astrophysics Data System (ADS)

    Huang, Xian Bin; Ren, Xiao Dong; Dan, Jia Kun; Wang, Kun Lun; Xu, Qiang; Zhou, Shao Tong; Zhang, Si Qun; Cai, Hong Chun; Li, Jing; Wei, Bing; Ji, Ce; Feng, Shu Ping; Wang, Meng; Xie, Wei Ping; Deng, Jian Jun

    2017-09-01

    The preliminary experimental results of Z-pinch dynamic hohlraums conducted on the Primary Test Stand (PTS) facility are presented herein. Six different types of dynamic hohlraums were used in order to study the influence of load parameters on radiation characteristics and implosion dynamics, including dynamic hohlraums driven by single and nested arrays with different array parameters and different foams. The PTS facility can deliver a current of 6-8 MA in the peak current and 60-70 ns in the 10%-90% rising time to dynamic hohlraum loads. A set of diagnostics monitor the implosion dynamics of plasmas, the evolution of shock waves in the foam and the axial/radial X-ray radiation, giving the key parameters characterizing the features of dynamic hohlraums, such as the trajectory and related velocity of shock waves, radiation temperature, and so on. The experimental results presented here put our future study on Z-pinch dynamic hohlraums on the PTS facility on a firm basis.

  11. First measurement of plasma stagnation radiation in a hohlraum in the Shenguang-III prototype

    NASA Astrophysics Data System (ADS)

    Ren, Kuan; Liu, Shenye; Xie, Xufei; Du, Huabing; Hou, Lifei; Jing, Longfei; Yang, Dong; Zhao, Yang; Yan, Ji; Yang, Zhiwen; Li, Zhichao; Dong, Jianjun; Xiao, Min; Yang, Guohong; Li, Sanwei; Cao, Zhurong; Chen, Yaohua; Lan, Ke; Ren, Guoli; Liu, Jie; Ding, Yongkun; Jiang, Shaoen

    2017-08-01

    The measurement of plasma stagnation radiation in a hohlraum is of key importance when exploring the influence of plasma stagnation on hohlraum drive symmetry in indirectly driven inertial confinement fusion experiments. In two typical hohlraum experiments conducted on the Shenguang-III prototype laser facility, the x-ray flux and radiation temperature from a plasma stagnation area 0.2 mm in diameter inside the hohlraum were measured for the first time through the hohlraum laser entrance hole (LEH) using a time and space-resolving flux detector (SRFD). The different flux intensities and radiation temperatures of the plasma stagnation area in the LEH measured using the SRFD were compared with the results detected for the entire LEH using flat-response x-ray detectors. The stagnation area radiation detected using the SRFD was found to be transient and 8.57% lower than that of the entire LEH, which is obviously higher than the tolerable drive asymmetry of an implosion. This important improvement in x-ray radiation measurement of plasma stagnation will further the quantitative understanding of the drive symmetry inside the hohlraum and conduct a strict adjustment for that.

  12. Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility

    SciTech Connect

    Izumi, N. Meezan, N. B.; Divol, L.; Hall, G. N.; Barrios, M. A.; Jones, O.; Landen, O. L.; Kroll, J. J.; Vonhof, S. A.; Nikroo, A.; Bailey, C. G.; Hardy, C. M.; Ehrlich, R. B.; Town, R. P. J.; Bradley, D. K.; Hinkel, D. E.; Moody, J. D.; Jaquez, J.

    2016-11-15

    The high fuel capsule compression required for indirect drive inertial confinement fusion requires careful control of the X-ray drive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagations and hence the X-ray drive symmetry especially at the final stage of the drive pulse. To quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Details of the experiment and the technique of spectrally selective x-ray imaging are discussed.

  13. Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Izumi, N.; Meezan, N. B.; Divol, L.; Hall, G. N.; Barrios, M. A.; Jones, O.; Landen, O. L.; Kroll, J. J.; Vonhof, S. A.; Nikroo, A.; Jaquez, J.; Bailey, C. G.; Hardy, C. M.; Ehrlich, R. B.; Town, R. P. J.; Bradley, D. K.; Hinkel, D. E.; Moody, J. D.

    2016-11-01

    The high fuel capsule compression required for indirect drive inertial confinement fusion requires careful control of the X-ray drive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagations and hence the X-ray drive symmetry especially at the final stage of the drive pulse. To quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Details of the experiment and the technique of spectrally selective x-ray imaging are discussed.

  14. Enchanced hohlraum radiation drive through reduction of wall losses with high-Z mixture "cocktail" wall materials

    SciTech Connect

    Schein, J; Jones, O; Rosen, M; Dewald, E; Glenzer, S; Gunther, J; Hammel, B; Landen, O; Suter, L; Wallace, R

    2006-05-17

    We present results from experiments, numerical simulations and analytic modeling, demonstrating enhanced hohlraum performance. Care in the fabrication and handling of hohlraums with walls consisting of high-Z mixtures (cocktails) has led to our demonstration, for the first time, of a significant increase in radiation temperature (up to +7eV at 300 eV) compared to a pure Au hohlraum, in agreement with predictions and ascribable to reduced wall losses. The data extrapolated to full NIF suggest we can expect an 18% reduction in wall loss for the current ignition design by switching to cocktail hohlraums, consistent with requirements for ignition with 1MJ laser energy.

  15. Progress towards a more predictive model for hohlraum radiation drive and symmetry

    PubMed Central

    Jones, O. S.; Suter, L. J.; Scott, H. A.; Hansen, S. B.; Liedahl, D. A.; Mauche, C. W.; Moore, A. S.; Rosen, M. D.; Salmonson, J. D.; Turnbull, D. P.

    2017-01-01

    For several years, we have been calculating the radiation drive in laser-heated gold hohlraums using flux-limited heat transport with a limiter of 0.15, tabulated values of local thermodynamic equilibrium gold opacity, and an approximate model for not in a local thermodynamic equilibrium (NLTE) gold emissivity (DCA_2010). This model has been successful in predicting the radiation drive in vacuum hohlraums, but for gas-filled hohlraums used to drive capsule implosions, the model consistently predicts too much drive and capsule bang times earlier than measured. In this work, we introduce a new model that brings the calculated bang time into better agreement with the measured bang time. The new model employs (1) a numerical grid that is fully converged in space, energy, and time, (2) a modified approximate NLTE model that includes more physics and is in better agreement with more detailed offline emissivity models, and (3) a reduced flux limiter value of 0.03. We applied this model to gas-filled hohlraum experiments using high density carbon and plastic ablator capsules that had hohlraum He fill gas densities ranging from 0.06 to 1.6 mg/cc and hohlraum diameters of 5.75 or 6.72 mm. The new model predicts bang times to within ±100 ps for most experiments with low to intermediate fill densities (up to 0.85 mg/cc). This model predicts higher temperatures in the plasma than the old model and also predicts that at higher gas fill densities, a significant amount of inner beam laser energy escapes the hohlraum through the opposite laser entrance hole. PMID:28611532

  16. Progress towards a more predictive model for hohlraum radiation drive and symmetry

    NASA Astrophysics Data System (ADS)

    Jones, O. S.; Suter, L. J.; Scott, H. A.; Barrios, M. A.; Farmer, W. A.; Hansen, S. B.; Liedahl, D. A.; Mauche, C. W.; Moore, A. S.; Rosen, M. D.; Salmonson, J. D.; Strozzi, D. J.; Thomas, C. A.; Turnbull, D. P.

    2017-05-01

    For several years, we have been calculating the radiation drive in laser-heated gold hohlraums using flux-limited heat transport with a limiter of 0.15, tabulated values of local thermodynamic equilibrium gold opacity, and an approximate model for not in a local thermodynamic equilibrium (NLTE) gold emissivity (DCA_2010). This model has been successful in predicting the radiation drive in vacuum hohlraums, but for gas-filled hohlraums used to drive capsule implosions, the model consistently predicts too much drive and capsule bang times earlier than measured. In this work, we introduce a new model that brings the calculated bang time into better agreement with the measured bang time. The new model employs (1) a numerical grid that is fully converged in space, energy, and time, (2) a modified approximate NLTE model that includes more physics and is in better agreement with more detailed offline emissivity models, and (3) a reduced flux limiter value of 0.03. We applied this model to gas-filled hohlraum experiments using high density carbon and plastic ablator capsules that had hohlraum He fill gas densities ranging from 0.06 to 1.6 mg/cc and hohlraum diameters of 5.75 or 6.72 mm. The new model predicts bang times to within ±100 ps for most experiments with low to intermediate fill densities (up to 0.85 mg/cc). This model predicts higher temperatures in the plasma than the old model and also predicts that at higher gas fill densities, a significant amount of inner beam laser energy escapes the hohlraum through the opposite laser entrance hole.

  17. Progress towards a more predictive model for hohlraum radiation drive and symmetry.

    PubMed

    Jones, O S; Suter, L J; Scott, H A; Barrios, M A; Farmer, W A; Hansen, S B; Liedahl, D A; Mauche, C W; Moore, A S; Rosen, M D; Salmonson, J D; Strozzi, D J; Thomas, C A; Turnbull, D P

    2017-05-01

    For several years, we have been calculating the radiation drive in laser-heated gold hohlraums using flux-limited heat transport with a limiter of 0.15, tabulated values of local thermodynamic equilibrium gold opacity, and an approximate model for not in a local thermodynamic equilibrium (NLTE) gold emissivity (DCA_2010). This model has been successful in predicting the radiation drive in vacuum hohlraums, but for gas-filled hohlraums used to drive capsule implosions, the model consistently predicts too much drive and capsule bang times earlier than measured. In this work, we introduce a new model that brings the calculated bang time into better agreement with the measured bang time. The new model employs (1) a numerical grid that is fully converged in space, energy, and time, (2) a modified approximate NLTE model that includes more physics and is in better agreement with more detailed offline emissivity models, and (3) a reduced flux limiter value of 0.03. We applied this model to gas-filled hohlraum experiments using high density carbon and plastic ablator capsules that had hohlraum He fill gas densities ranging from 0.06 to 1.6 mg/cc and hohlraum diameters of 5.75 or 6.72 mm. The new model predicts bang times to within ±100 ps for most experiments with low to intermediate fill densities (up to 0.85 mg/cc). This model predicts higher temperatures in the plasma than the old model and also predicts that at higher gas fill densities, a significant amount of inner beam laser energy escapes the hohlraum through the opposite laser entrance hole.

  18. Experimental room temperature hohlraum performance study on the National Ignition Facility [Experimental evidence for improved performance in room temperature hohlraums on the National Ignition Facility

    SciTech Connect

    Ralph, J. E.; Strozzi, D.; Ma, T.; Moody, J. D.; Hinkel, D. E.; Callahan, D. A.; MacGowan, B. J.; Michel, P.; Kline, J. L.; Glenzer, S. H.; Albert, F.; Benedetti, L. R.; Divol, L.; MacKinnon, A. J.; Pak, A.; Rygg, J. R.; Schneider, M. B.; Town, R. P. J.; Widmann, K.; Hsing, W.; Edwards, M. J.

    2016-12-29

    Room temperature or “warm” (273 K) indirect drive hohlraum experiments have been conducted on the National Ignition Facility with laser energies up to 1.26 MJ and compared to similar cryogenic or “cryo” (~20 K) experiments. Warm experiments use neopentane (C5H12) as the low pressure hohlraum fill gas instead of helium, and propane (C3H8) to replace the cryogenic DT or DHe3 capsule fill. The increased average Z of the hohlraum fill leads to increased inverse bremsstrahlung absorption and an overall hotter hohlraum plasma in simulations. The cross beam energy transfer (CBET) from outer laser beams (pointed toward the laser entrance hole) to inner beams (pointed at the equator) was inferred indirectly from measurements of Stimulated Raman Scattering (SRS). These experiments show that a similar hot spot self-emission shape can be produced with less CBET in warm hohlraums. The measured inner cone SRS reflectivity (as a fraction of incident power neglecting CBET) is ~2.5× less in warm than cryo shots with similar hot spot shapes, due to a less need for CBET. The measured outer-beam stimulated the Brillouin scattering power that was higher in the warm shots, leading to a ceiling on power to avoid the optics damage. These measurements also show that the CBET induced by the flow where the beams cross can be effectively mitigated by a 1.5 Å wavelength shift between the inner and outer beams. A smaller scale direct comparison indicates that warm shots give a more prolate implosion than cryo shots with the same wavelength shift and pulse shape. Lastly, the peak radiation temperature was found to be between 5 and 7 eV higher in the warm than the corresponding cryo experiments after accounting for differences in backscatter.

  19. Experimental room temperature hohlraum performance study on the National Ignition Facility [Experimental evidence for improved performance in room temperature hohlraums on the National Ignition Facility

    DOE PAGES

    Ralph, J. E.; Strozzi, D.; Ma, T.; ...

    2016-12-29

    Room temperature or “warm” (273 K) indirect drive hohlraum experiments have been conducted on the National Ignition Facility with laser energies up to 1.26 MJ and compared to similar cryogenic or “cryo” (~20 K) experiments. Warm experiments use neopentane (C5H12) as the low pressure hohlraum fill gas instead of helium, and propane (C3H8) to replace the cryogenic DT or DHe3 capsule fill. The increased average Z of the hohlraum fill leads to increased inverse bremsstrahlung absorption and an overall hotter hohlraum plasma in simulations. The cross beam energy transfer (CBET) from outer laser beams (pointed toward the laser entrance hole)more » to inner beams (pointed at the equator) was inferred indirectly from measurements of Stimulated Raman Scattering (SRS). These experiments show that a similar hot spot self-emission shape can be produced with less CBET in warm hohlraums. The measured inner cone SRS reflectivity (as a fraction of incident power neglecting CBET) is ~2.5× less in warm than cryo shots with similar hot spot shapes, due to a less need for CBET. The measured outer-beam stimulated the Brillouin scattering power that was higher in the warm shots, leading to a ceiling on power to avoid the optics damage. These measurements also show that the CBET induced by the flow where the beams cross can be effectively mitigated by a 1.5 Å wavelength shift between the inner and outer beams. A smaller scale direct comparison indicates that warm shots give a more prolate implosion than cryo shots with the same wavelength shift and pulse shape. Lastly, the peak radiation temperature was found to be between 5 and 7 eV higher in the warm than the corresponding cryo experiments after accounting for differences in backscatter.« less

  20. 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×.

  1. Comparison of high-density carbon implosions in unlined uranium versus gold hohlraums

    NASA Astrophysics Data System (ADS)

    Dewald, Eduard; Meezan, Nathan; Tommasini, Riccardo; Khan, Shahab; MacKinnon, Andrew; Berzak Hopkins, Laura; Divol, Laurent; Lepape, Sebastien; Moore, Alastair; Schneider, Marilyn; Pak, Arthur; Nikroo, Abbas; Landen, Otto

    2016-10-01

    In Inertial Confinement Fusion (ICF) implosions, laser energy is converted to x-ray radiation in hohlraums with High-Z walls. At radiation temperatures near 300 eV relevant for ICF experiments, the radiative losses in heating the wall are lower for U than for Au hohlraums. Furthermore, the intensity of the ``M-band'' x-rays with photon energies h ν >1.8 keV is lower for uranium, allowing for reduced capsule dopant concentrations employed to minimize inner ablator preheat and hence keep favorable fuel/ablator interface Atwood numbers. This in turn improves the ablator rocket efficiency and reduces the risk of polluting the hot-spot with emissive dopant material. The first uranium vacuum hohlraum experiments on the National Ignition Facility (NIF) with undoped high-density carbon (HDC, or diamond) capsules have demonstrated 30% lower ``M-band'' intensity relative to Au, resulting in lower inflight ablator thickness due to reduced preheat. In addition, fusion neutron yields are 2x higher in U than in Au hohlraums for D2-gas filled capsule implosions at ICF relevant velocities of 380 +/-20 km/s. These results have led the NIF ICF implosions to routinely employ U hohlraums. Prepared by LLNL under Contract DE-AC52-07NA27344.

  2. Gas-filled Rugby hohlraum energetics and implosions experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, Alexis; Philippe, F.; Tassin, V.; Seytor, P.; Monteil, M. C.; Villette, B.; Reverdin, C.

    2010-11-01

    Recent experiments [1,2] have validated the x-ray drive enhancement provided by rugby-shaped hohlraums over cylinders in the indirect drive (ID) approach to inertial confinement fusion (ICF). This class of hohlraum is the baseline design for the Laser Mégajoule program, is also applicable to the National Ignition Facility and could therefore benefit ID Inertial Fusion Energy studies. We have carried out a serie of energetics and implosions experiments with OMEGA ``scale 1'' rugby hohlraums [1,2]. For empty hohlraums these experiments provide complementary measurements of backscattered light along 42 cone, as well as detailed drive history. In the case of gas-filled rugby hohlraums we have also study implosion performance (symmetry, yield, bangtime, hotspot spectra...) using a high contrast shaped pulse leading to a different implosion regime and for a range of capsule convergence ratios. These results will be compared with FCI2 hydrocodes calculations and future experimental campaigns will be suggested. [4pt] [1] F. Philippe et al., Phys. Rev. Lett. 104, 035004 (2010). [0pt] [2] H. Robey et al., Phys. Plasnas 17, 056313 (2010).

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

    DOE PAGES

    Berzak Hopkins, L.  F.; Meezan, N.  B.; Le Pape, S.; ...

    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

  4. Non-destructive analysis of DU content in the NIF hohlraums

    SciTech Connect

    Gharibyan, Narek; Moody, Ken J.; Shaughnessy, Dawn A.

    2015-12-16

    The advantage of using depleted uranium (DU) hohlraums in high-yield deuterium-tritium (DT) shots at the National Ignition Facility (NIF) is addressed by Döppner, et al., in great detail [1]. This DU based hohlraum incorporates a thin layer of DU, ~7 μm thick, on the inner surface along with a thin layer of a gold coating, ~0.7 μm thick, while the outer layer is ~22 μm thick gold. A thickness measurement of the DU layer can be performed using an optical microscope where the total DU weight can be computed provided a uniform DU layer. However, the uniformity of the thickness is not constant throughout the hohlraum since CAD drawing calculations of the DU weight do not agree with the computed values from optical measurements [2]. Therefore, a non-destructive method for quantifying the DU content in hohlraums has been established by utilizing gamma-ray spectroscopy. The details of this method, along with results from several hohlraums, are presented in this report.

  5. 3D Simulations of the ``Keyhole'' Hohlraum for Shock Timing on NIF

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Marinak, M. M.; Munro, D. H.; Jones, O. S.

    2007-11-01

    Ignition implosions planned for the National Ignition Facility (NIF) require a pulse shape with a carefully designed series of steps, which launch a series of shocks through the ablator and DT fuel. The relative timing of these shocks must be tuned to better than +/- 100ps to maintain the DT fuel on a sufficiently low adiabat. To meet these requirements, pre-ignition tuning experiments using a modified hohlraum geometry are being planned. This modified geometry, known as the ``keyhole'' hohlraum, adds a re-entrant gold cone, which passes through the hohlraum and capsule walls, to provide an optical line-of-sight to directly measure the shocks as they break out of the ablator. In order to assess the surrogacy of this modified geometry, 3D simulations using HYDRA [1] have been performed. The drive conditions and the resulting effect on shock timing in the keyhole hohlraum will be compared with the corresponding results for the standard ignition hohlraum. [1] M.M. Marinak, et al., Phys. Plasmas 8, 2275 (2001).

  6. Optimizing the hohlraum gas density for better symmetry control of indirect drive implosion experiments

    NASA Astrophysics Data System (ADS)

    Izumi, Nobuhiko; Hall, G. N.; Nagel, S. R.; Khan, S.; Rygg, R. R.; MacKinnon, A. J.; Ho, D. D.; Berzak Hopkins, L.; Jones, O. S.; Town, R. P. J.; Bradley, D. K.

    2014-10-01

    To achieve a spherically symmetric implosion, control of drive uniformity is essential. Both the ablation pressure and the mass ablation rate on the capsule surface should be made as uniform as possible for the duration of the drive. For an indirect drive implosion, the drive uniformity changes during the pulse because of: (1) the dynamic movement of the laser spots due to blow-off of the hohlraum wall, and (2) cross-beam energy transfer caused by laser-plasma interaction in the hohlraum. To tamp the wall blow-off, we use gas filled hohlraums. The cross-beam energy transfer can be controlled by applying a wave length separation between the cones of the laser beams. However, both of those dynamic effects are sensitive to the initial density of the hohlraum gas fill. To assess this, we performed implosion experiments with different hohlraum gas densities and tested the effect on drive asymmetry. The uniformity of the acceleration was measured by in-flight x-ray backlit imaging of the capsule. The uniformity of the core assembly was observed by imaging the self emission x-ray from the core. We will report on the experimental results and compare them to hydrodynamic simulations. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-626372.

  7. 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 × .

  8. Direct-drive Energetics of laser-Heated Foam Liners for Hohlraums

    NASA Astrophysics Data System (ADS)

    Moore, Alastair; Thomas, Cliff; Baker, Kevin; Morton, John; Baumann, Ted; Biener, Monika; Bhandarkar, Suhas; Hinkel, Denise; Jones, Oggie; Meezan, Nathan; Moody, John; Nikroo, Abbas; Rosen, Mordy; Hsing, Warren

    2016-10-01

    Lining the walls of a high-Z hohlraum cavity with a low-density foam is predicted to mitigate the challenge presented by hohlraum wall expansion. Once heated, wall material quickly fills the cavity and can impede laser beam propagation. To avoid this, ignition hohlraums are typically filled with a gas or irradiated with a short (< 10 ns) laser pulse. A gas-fill has the disadvantage that it can cause laser plasma instabilities (LPI), while a short laser pulse limits the design space to reach low-adiabat implosions. Foam-liners offer a potential route to reduce wall motion in a low gas-fill hohlraum with little LPI. Results from quasi 1-D experiments performed at the NIF are presented These characterize the x-ray conversion efficiency, backscattered laser energy and heat propagation in a 250 μm thick Ta2O5 or ZnO foam-liners spanning a range of densities from underdense to overdense, when irradiated at up to 4.9 x 1014 W/cm2 is incident on a planar foam sample, backed by a Au foil and generates a radiation temperature of up to 240eV - conditions equivalent to a single outer cone beam-spot in an ignition hohlraum. 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. A spherical hohlraum design with tetrahedral 4 laser entrance holes and high radiation performance

    NASA Astrophysics Data System (ADS)

    Jiang, Shaoen; Jing, Longfei; Huang, Yunbao; Li, Haiyan; Huang, Tianxuan; Ding, Yongkun

    2016-12-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious laser-plasma interaction, such as the simulated Raman scatter and cross-beam energy transfer effect, spherical hohlraum with octahedral 6 Laser Entrance Holes (LEHs) and single cone laser beams, was investigated and reported to have a consistent high radiation symmetry during the whole implosion process. However, it has several potential challenges such as the smaller space left for diagnosis and the assembly of centrally located capsule. In this paper, based on the view-factor model, we investigate the radiation symmetry and the drive temperature on the capsule located in the spherical hohlraum with tetrahedral 4 LEHs and single cone laser beams, since there is more available space for laser disposition and diagnosis. Then, such target is optimized on the laser beam pointing direction to achieve a high radiation performance, i.e., the radiation symmetry and drive temperature on the capsule. Finally, an optimal spherical hohlraum with optimal laser beam pointing has been demonstrated and compared with the spherical hohlraum with octahedral 6 LEHs. The resulting radiation symmetry and the drive temperature shows that it has almost a similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and an additional 133 kJ energy of 2 MJ energy for fusion can be saved).

  10. Mitigating Laser-Plasma Instabilities in Hohlraum Laser-Plasmas Using Magnetic Insulation

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Simakov, A.; Albright, B. J.; Yin, L.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.

    2012-10-01

    Controlling laser-plasma instabilities in hohlraum plasmas is important for achieving high-gain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense low-Z plasma to the dense high-Z hohlraum wall [1]. This leads to weaker Landau damping and stronger growth of parametric instabilities. For NIF laser-plasma conditions, it is shown that a 10-T external magnetic field may substantially reduce cross-field transport and may increase plasma temperatures, thus increasing linear Landau damping and mitigating parametric instabilities. Additional benefits may be realized since the hot electrons will be strongly magnetized and may be prevented from reaching the capsule or hohlraum walls. We will present calculations and simulations supporting this concept, and describe experimental plans to test the concept using gas-filled hohlraums at the Omega Laser Facility.[4pt] [1] M.D. Rosen et al., High Eng. Dens. Phys. 7, 180 (2011).

  11. 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.

  12. Revisiting hot electron generation in ignition-scale hohlraums

    NASA Astrophysics Data System (ADS)

    Kruer, William; Thomas, Cliff; Strozzi, David; Meezan, Nathan; Landen, Otto; Robey, Harry

    2014-10-01

    Recent work invoking hot electron preheat in NIC ignition experiments is motivating a fresh look at hot electron generation in ignition-scale hohlraums. Various mechanisms for high energy electron generation are considered, with particular attention to their time dependence and the potential role of the two plasmon decay instability in the main laser pulse. The energy at risk calculations are updated to include the effects of cross beam energy transfer on the time-dependent energy and intensity of the inner beams as well as improvements in the calculated plasma conditions. The generation of hot electrons by the Raman-scattered light driving the two plasmon decay instability and the effect of the Weibel instability on the propagation of the hot electrons are also briefly considered. Uncertainties in interpreting the energy in hot electrons from hard x-ray measurements and techniques to reduce hot electron generation are discussed. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract DE-AC52-07NA27344.

  13. Axial radiation asymmetry in dynamic hohlraums diagnosed spectro-scopically

    NASA Astrophysics Data System (ADS)

    Sanford, T. W. L.; Nash, T. J.; Mock, R. C.; Bailey, J. E.; Chandler, G. A.; Jobe, D. O.; Lake, P. W.; Leeper, R. J.; Lucas, J. M.; Mehlhorn, T. H.; Moore, T. C.; Nielson, D. S.; Apruzese, J. P.; Clark, R. W.; Kepple, P. C.; Davis, J.; Macfarlane, J. J.; Watt, R. C.; Peterson, D. L.; Chrien, R. E.; Idzorek, G. C.; Roderick, N. F.

    2003-10-01

    Dynamic-hohlraums (DH) driven by a Z pinch are being developed and used as intense blackbody x-ray sources for ICF and radiation-transport experiments. These sources have exhibited an unexpected axial asymmetry in their radiated power [1]. A new spectrometer system has been developed that enables the spectral emission to be measured exiting the bottom of the DH as well as the top. K-shell lines observed, with this system, mostly in absorption from Al and Mg tracer layers embedded within the DH are used to estimate the emission temperature at either end. Tungsten plasma, observed to prematurely slide across the bottom aperture, likely accounts for the bulk of the measured axial asymmetry. Possible models will be discussed. [1] T. W. L. Sanford, R. C. Mock, R. J. Leeper, D. L. Peterson, R. C. Watt, R. E. Chrien, G. C. Idzorek, B. V. Oliver, N. F. Roderick, and M. G. Haines, Phys.Plasmas 10, 1187 (2003). *Sandia is a multiprogram laboratory operated by the Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract No. DE-AC04-94AL85000.

  14. Integrated P1 Hohlraum/Capsule Simulations for NIF Experiments

    NASA Astrophysics Data System (ADS)

    Eder, David; Spears, Brian; Town, Richard; Jones, Oggie; Ma, Tammy; Pak, Arthur; Benedetti, Robin; Hatchett, Steve; Knauer, James; MacKinnon, Andrew; Yeamans, Charles; McNaney, James; Casey, Daniel

    2014-10-01

    We discuss integrated hohlraum/capsule post-shot simulations of two full-scale cryogenic NIF experiments that drove a DT symcap capsule downward/upward by having the peak power in the upper laser beams 16% greater/less than the lower beams. This laser asymmetry results in a radiation drive P1/P0 at the capsule ablation surface of ~2% and a downward/upward capsule velocity of order 100 microns/ns in agreement with the data. The experimental velocity is determined by comparing measurements at different locations of both the arrival times of DD and DT neutrons at time-of-flight detectors, and by zirconium activation measurements that are a function of neutron energy. We compare these two shots to a control shot for the same target with no specified laser asymmetries. We also discuss simulations of planned sub-scale warm symcap experiments that have a goal of measuring DT and DD ion temperatures and the electron temperature as a function of the imposed P1 to characterize the role of non-thermal velocity on temperature measurements. This work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-656659.

  15. Laser-generated magnetic fields in quasi-hohlraum geometries

    NASA Astrophysics Data System (ADS)

    Pollock, Bradley; Turnbull, David; Ross, Steven; Hazi, Andrew; Ralph, Joseph; Lepape, Sebastian; Froula, Dustin; Haberberger, Dan; Moody, John

    2014-10-01

    Laser-generated magnetic fields of 10--40 T have been produced with 100--4000 J laser drives at Omega EP and Titan. The fields are generated using the technique described by Daido et al. [Phys. Rev. Lett. 56, 846 (1986)], which works by directing a laser through a hole in one plate to strike a second plate. Hot electrons generated in the laser-produced plasma on the second plate collect on the first plate. A strap connects the two plates allowing a current of 10 s of kA to flow and generate a solenoidal magnetic field. The magnetic field is characterized using Faraday rotation, b-dot probes, and proton radiography. Further experiments to study the effect of the magnetic field on hohlraum performance are currently scheduled for Omega. This work was performed under the auspices of the United States Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA-27344.

  16. Characterizing high energy spectra of NIF ignition Hohlraums using a differentially filtered high energy multipinhole x-ray imager.

    PubMed

    Park, Hye-Sook; Dewald, E D; Glenzer, S; Kalantar, D H; Kilkenny, J D; MacGowan, B J; Maddox, B R; Milovich, J L; Prasad, R R; Remington, B A; Robey, H F; Thomas, C A

    2010-10-01

    Understanding hot electron distributions generated inside Hohlraums is important to the national ignition campaign for controlling implosion symmetry and sources of preheat. While direct imaging of hot electrons is difficult, their spatial distribution and spectrum can be deduced by detecting high energy x-rays generated as they interact with target materials. We used an array of 18 pinholes with four independent filter combinations to image entire Hohlraums with a magnification of 0.87× during the Hohlraum energetics campaign on NIF. Comparing our results with Hohlraum simulations indicates that the characteristic 10-40 keV hot electrons are mainly generated from backscattered laser-plasma interactions rather than from Hohlraum hydrodynamics.

  17. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-01

    A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  18. Radiation transport and energetics of laser-driven half-hohlraums at the National Ignition Facility

    SciTech Connect

    Moore, A. S. Graham, P.; Comley, A. J.; Foster, J.; Cooper, A. B. R.; Schneider, M. B.; MacLaren, S.; Lu, K.; Seugling, R.; Satcher, J.; Klingmann, J.; Marrs, R.; May, M.; Widmann, K.; Glendinning, G.; Castor, J.; Sain, J.; Baker, K.; Hsing, W. W.; Young, B.; and others

    2014-06-15

    Experiments that characterize and develop a high energy-density half-hohlraum platform for use in benchmarking radiation hydrodynamics models have been conducted at the National Ignition Facility (NIF). Results from the experiments are used to quantitatively compare with simulations of the radiation transported through an evolving plasma density structure, colloquially known as an N-wave. A half-hohlraum is heated by 80 NIF beams to a temperature of 240 eV. This creates a subsonic diffusive Marshak wave, which propagates into a high atomic number Ta{sub 2}O{sub 5} aerogel. The subsequent radiation transport through the aerogel and through slots cut into the aerogel layer is investigated. We describe a set of experiments that test the hohlraum performance and report on a range of x-ray measurements that absolutely quantify the energetics and radiation partition inside the target.

  19. A coordinate transformation method for calculating the 3D light intensity distribution in ICF hohlraum

    NASA Astrophysics Data System (ADS)

    Lin, Zhili; Li, Xiaoyan; Zhao, Kuixia; Chen, Xudong; Chen, Mingyu; Pu, Jixiong

    2016-06-01

    For an inertial confinement fusion (ICF) system, the light intensity distribution in the hohlraum is key to the initial plasma excitation and later laser-plasma interaction process. Based on the concept of coordinate transformation of spatial points and vector, we present a robust method with a detailed procedure that makes the calculation of the three dimensional (3D) light intensity distribution in hohlraum easily. The method is intuitive but powerful enough to solve the complex cases of random number of laser beams with arbitrary polarization states and incidence angles. Its application is exemplified in the Shenguang III Facility (SG-III) that verifies its effectiveness and it is useful for guiding the design of hohlraum structure parameter.

  20. Radiation transport and energetics of laser-driven half-hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Moore, A. S.; Cooper, A. B. R.; Schneider, M. B.; MacLaren, S.; Graham, P.; Lu, K.; Seugling, R.; Satcher, J.; Klingmann, J.; Comley, A. J.; Marrs, R.; May, M.; Widmann, K.; Glendinning, G.; Castor, J.; Sain, J.; Back, C. A.; Hund, J.; Baker, K.; Hsing, W. W.; Foster, J.; Young, B.; Young, P.

    2014-06-01

    Experiments that characterize and develop a high energy-density half-hohlraum platform for use in benchmarking radiation hydrodynamics models have been conducted at the National Ignition Facility (NIF). Results from the experiments are used to quantitatively compare with simulations of the radiation transported through an evolving plasma density structure, colloquially known as an N-wave. A half-hohlraum is heated by 80 NIF beams to a temperature of 240 eV. This creates a subsonic diffusive Marshak wave, which propagates into a high atomic number Ta2O5 aerogel. The subsequent radiation transport through the aerogel and through slots cut into the aerogel layer is investigated. We describe a set of experiments that test the hohlraum performance and report on a range of x-ray measurements that absolutely quantify the energetics and radiation partition inside the target.

  1. Radiation transport and energetics of laser-driven half-hohlraums at the National Ignition Facility

    SciTech Connect

    Moore, A. S.; Cooper, A. B.R.; Schneider, M. B.; MacLaren, S.; Graham, P.; Lu, K.; Seugling, R.; Satcher, J.; Klingmann, J.; Comley, A. J.; Marrs, R.; May, M.; Widmann, K.; Glendinning, G.; Castor, J.; Sain, J.; Back, C. A.; Hund, J.; Baker, K.; Hsing, W. W.; Foster, J.; Young, B.; Young, P.

    2014-06-01

    Experiments that characterize and develop a high energy-density half-hohlraum platform for use in bench-marking radiation hydrodynamics models have been conducted at the National Ignition Facility (NIF). Results from the experiments are used to quantitatively compare with simulations of the radiation transported through an evolving plasma density structure, colloquially known as an N-wave. A half-hohlraum is heated by 80 NIF beams to a temperature of 240 eV. This creates a subsonic di usive Marshak wave which propagates into a high atomic number Ta2O5 aerogel. The subsequent radiation transport through the aerogel and through slots cut into the aerogel layer is investigated. We describe a set of experiments that test the hohlraum performance and report on a range

  2. Observations of electromagnetic fields and plasma flow in hohlraums with proton radiography

    SciTech Connect

    Li, C K; Seguin, F H; Frenje, J A; Petrasso, R D; Amendt, P A; Town, R J; Landen, O L; Rygg, J R; Betti, R; Knauer, J P; Meyerhofer, D D; Soures, J M; Back, C A; Kilkenny, J D; Nikroo, A

    2009-01-29

    The authors report on the first proton radiography of laser-irradiated hohlraums. This experiment, with vacuum gold (Au) hohlraums, resulted in observations of self-generated electric and magnetic fields. Peak values are {approx} 10{sup 9} V m{sup -1} and {approx} 10{sup 6} gauss. Time-gated radiographs of monoenergetic protons with discrete energies (15.0 and 3.3 MeV) reveal dynamic pictures of field structures and plasma flow. Near the end of the 1-ns laser drive, a stagnating Au plasma ({approx} 10 mg cm{sup -3}) forms at the center of the hohlraum, a consequence of supersonic, radially directed Au jets ({approx} 1000 {micro}m ns{sup -1}, {approx} Mach 4) as laser-driven plasma bubbles approaching one another.

  3. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    SciTech Connect

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-15

    A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  4. Characterizing high energy spectra of NIF ignition hohlraums using a differentially filtered high energy multi-pinhole X-ray imager

    SciTech Connect

    Park, H; Dewald, E D; Glenzer, S; Kalantar, D H; Kilkenny, J D; MacGowan, B J; Maddox, B R; Milovich, J L; Prasad, R R; Remington, B A; Thomas, C A

    2010-05-11

    Understanding hot electron distributions generated inside hohlraums is important to the ignition campaign for controlling implosion symmetry and sources of preheat. While direct imaging of hot electrons is difficult, their spatial distribution and spectrum can be deduced by detecting high energy x-rays generated as they interact with the target materials. We used an array of 18 pinholes, with four independent filter combinations, to image entire hohlraums with a magnification of 0.87x during the hohlraum energetics campaign on NIF. Comparing our results with hohlraum simulations indicates that the characteristic 30 keV hot electrons are mainly generated from backscattered laser plasma interactions rather than from hohlraum hydrodynamics.

  5. High Performance Capsule Implosions on the Omega Laser Facility with Rugby Hohlraums

    NASA Astrophysics Data System (ADS)

    Robey, Harry F.

    2009-11-01

    Rugby-shaped hohlraums have been proposed as a method for x-ray drive enhancement for indirectly-driven capsule implosions [1]. This concept has recently been tested in a series of shots on the OMEGA laser facility at the Laboratory for Laser Energetics at the University of Rochester. In this talk, experimental results are presented comparing the performance of D2-filled capsules between standard cylindrical Au hohlraums and rugby-shaped hohlraums. Not only did the rugby hohlraums demonstrate 18% more x-ray drive energy as compared with the cylinders, but the high-performance design of these implosions (both cylinder and rugby) also provided 20X more DD neutrons than any previous indirectly-driven campaign on Omega (and 3X more than ever achieved on Nova implosions driven with nearly twice the laser energy). This increase in performance enables, for the first time, a measurement of the neutron burn history of 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^3He rather than D2 fuel. Comparisons of the experimental results with numerical simulations are shown to be in excellent agreement. The design techniques employed in this campaign, e.g., smaller NIF-like laser entrance holes and hohlraum case-to-capsule ratios, provide added confidence in the pursuit of ignition on the National Ignition Facility. [4pt] [1] P. Amendt, C. Cerjan, D. E. Hinkel, J. L. Milovich, H.-S. Park, and H. F. Robey, ``Rugby-like hohlraum experimental designs for demonstrating x-ray drive enhancement'', Phys. Plasmas 15, 012702 (2008).

  6. Images of the gold bubble feature in NIF Gas-Filled Ignition Hohlraums

    NASA Astrophysics Data System (ADS)

    Schneider, M. B.; MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Bradley, D. K.; Callahan, D. A.; Edwards, M. J.; Guymer, T. M.; Hinkel, D. E.; Hsing, W. W.; Kervin, M. L.; Landen, O. L.; Moody, J. D.; Moore, A. S.; Palmer, N. E.; Teruya, A. T.

    2016-05-01

    The ViewFactor experiments at the National Ignition Facility use a truncated hohlraum to allow excellent diagnostic views of the interior of the hohlraum. Time-integrated, hard x-ray (3-5 keV) images show the region where the laser deposits its energy at peak power. These images show a three-dimensional structure in the region where the outer beams deposit their energy (the ”gold bubble”) which varies with pulse shape and cross beam energy transfer. The images from two-dimensional simulations have similar trends but show some discrepancies.

  7. The Prospects for High-Yield ICF with a Z-Pinch Driven Dynamic Hohlraum

    SciTech Connect

    CHANDLER, GORDON A.; CHRIEN, R.; COOPER, GARY WAYNE; DERZON, MARK S.; DOUGLAS, MELISSA R.; HEBRON, DAVID E.; LASH, JOEL S.; LEEPER, RAMON J.; MATZEN, M. KEITH; MEHLHORN, THOMAS A.; NASH, THOMAS J.; OLSON, RICHARD E.; PETERSON, D.L.; RUIZ, CARLOS L.; SANFORD, THOMAS W. L.; SLUTZ, STEPHEN A.

    1999-09-07

    Recent success with the Sandia Z machine has renewed interest in utilizing fast z-pinenes for ICF. One promising concept places the ICF capsule internal to the imploding z-pinch. At machine parameters relevant to achieving high yield, the imploding z-pinch mass has sufficient opacity to trap radiation giving rise to a dynamic hohlraum. The concept utilizes a 12 MJ, 54 MA z-pinch driver producing a capsule drive temperature exceeding 300 eV to realize a 550 MJ thermonuclear yield. They present the current high-yield design and its development that supports high-yield ICF with a z-pinch driven dynamic hohlraum.

  8. Suppression of Stimulated Brillouin Scattering in multiple-ion species inertial confinemen fusion Hohlraum Plasmas

    SciTech Connect

    Neumayer, P

    2007-05-14

    A long-standing problem in the field of laser-plasma interactions is to successfully employ multiple-ion species plasmas to reduce stimulated Brillouin scattering (SBS) in inertial confinement fusion (ICF) hohlraum conditions. Multiple-ion species increase significantly the linear Landau damping for acoustic waves. Consequently, recent hohlraum designs for indirect-drive ignition on the National Ignition Facility investigate wall liner material options so that the liner gain for parametric instabilities will be below threshold for the onset SBS. Although the effect of two-ion species plasmas on Landau damping has been directly observed with Thomson scattering, early experiments on SBS in these plasmas have suffered from competing non-linear effects or laser beam filamentation. In this study, a reduction of SBS scattering to below the percent level has been observed in hohlraums at Omega that emulate the plasma conditions in an indirect drive ICF experiments. These experiments have measured the laser-plasma interaction processes in ignition-relevant high-electron temperature regime demonstrating Landau damping as a controlling process for SBS. The hohlraums have been filled with various fractions of CO{sub 2} and C{sub 3}H{sub 8} varying the ratio of the light (H) to heavy (C and O) ion density from 0 to 2.6. They have been heated by 14.5 kJ of 351-nm light, thus increasing progressively Landau damping by an order of magnitude at constant electron density and temperature. A delayed 351-nm interaction beam, spatially smoothed to produce a 200-{micro}m laser spot at best focus, has propagated along the axis of the hohlraum. The backscattered light, both into the lens and outside, the transmitted light through the hohlraum plasma and the radiation temperature of the hohlraum has been measured. For ignition relevant laser intensities (3-9 10{sup 14} Wcm{sup -2}), we find that the SBS reflectivity scales as predicted with Landau damping from >30% to <1%. Simultaneously

  9. Measurements of Laser-Plasma Instability Relevant to Ignition Hohlraums

    NASA Astrophysics Data System (ADS)

    Fernández, Juan C.

    1996-11-01

    footnotetext[1]This work is supported by the US DOE. footnotetext[2]In collaboration with: B.S. Bauer, J.A. Cobble, D.F. DuBois, G.A. Kyrala, D.S. Montgomery, H.A. Rose, H.X. Vu, R.G. Watt, B.H. Wilde, M.D. Wilke, W.M. Wood, Los Alamos National Laboratory; R. Kirkwood, B.J. MacGowan, Lawrence Livermore National Laboratory; B.H. Failor, Physics International. Recent experimental observations contribute to a much better understanding of laser interactions with plasmas having the long scale lengths and high electron densities (n_e) and temperatures (T_e) expected within hohlraums designed to drive a fusion capsule to ignition. Some important effects being observed and explained theoretically are intimately related to the presence of hot spots in high-energy lasers. For example, measured onset intensities for strong stimulated Brillouin and Raman scattering (SBS and SRS) in various plasma conditions are consistent with predictions from models which include realistic hot-spot statistics. We also present direct experimental evidence that the combination of plasma flow transverse to a laser beam and self-focusing can deflect the beam, an effect unrelated to conventional refraction. In these plasmas, SRS could saturate at a level where the SRS Langmuir-wave amplitude is sufficiently high for it to be strongly unstable to parametric decay involving a daughter ion-acoustic wave. In support of this model, the measured SRS reflectivity depends on ion acoustic damping, which should otherwise be unrelated to SRS. This saturation mechanism is predicted to become ineffective at the highest Te and lowest ne values, where fortunately the calculated SRS onset intensity is highest and could exceed the desired laser intensity. The SBS and SRS light at the target plane can now be imaged to study correlations between SRS and SBS. The initial results from this study are also presented.

  10. Effects of plasma physics on capsule implosions in gas-filled hohlraums

    SciTech Connect

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

    1994-10-01

    Initial experiments on capsule implosions in gas-filled hohlraums have been carried out on the NOVA Laser at Lawrence Livermore National Laboratory. Observed capsule shapes from preliminary experiments are more oblate than predicted. Improvements in modeling required to calculate these experiments and additional experiments are being pursued.

  11. A simple model of hohlraum power balance and mitigation of SRS

    SciTech Connect

    Albright, Brian J.; Montgomery, David S.; Yin, Lin; Kline, John L.

    2016-01-01

    A simple energy balance model has been obtained for laser-plasma heating in indirect drive hohlraum plasma that allows rapid temperature scaling and evolution with parameters such as plasma density and composition. Furthermore, this model enables assessment of the effects on plasma temperature of, e.g., adding high-Z dopant to the gas fill or magnetic fields.

  12. Towards a more precise driving of capsules in ignition-scale hohlraums

    NASA Astrophysics Data System (ADS)

    Kruer, William; Thomas, Cliff

    2016-10-01

    Precision Nova experiments demonstrated the importance of rather precisely irradiating the interior walls of a hohlraum, even for imploding capsules to a convergence ratio of 20. Designs of precision implosions in a gas-filled ignition-scale hohlraum to even higher convergence would benefit from an improved understanding of both the plasma conditions and the laser energy deposition in time and space. The plasma conditions are sensitive to heat transport inhibition, which has been a recurrent theme in experiments with earlier lasers. Such inhibition has been proposed in order to better model NIF gas-filled hohlraums. An improved self-consistent model for the commonly invoked inhibition by two-stream turbulence is outlined, and some simple estimates made. These estimates suggest that the postulated reduction in heat transport may sometimes actually be due to other processes, such as self-generated magnetic fields. Several ways to reduce such B field effects are discussed, including greater temporal smoothing of speckle structure in the laser beams and reduction of intensity structure due to CBET and beam overlap on the hohlraum walls. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  13. New compact hohlraum configuration research at the 1.7 MA Z-pinch generator

    SciTech Connect

    Kantsyrev, V. L. Shrestha, I. K.; Esaulov, A. A.; Safronova, A. S.; Shlyaptseva, V. V.; Osborne, G. C.; Astanovitsky, A. L.; Weller, M. E.; Stafford, A.; Schultz, K. A.; Cooper, M. C.; Chuvatin, A. S.; Rudakov, L. I.; Velikovich, A. L.; Cuneo, M. E.; Jones, B.; Vesey, R. A.

    2014-12-15

    A new compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources was experimentally demonstrated in a full configuration with a central target and tailored shine shields (to provide a symmetric temperature distribution on the target) at the 1.7 MA Zebra generator. This presentation reports on the joint success of two independent lines of research. One of these was the development of new sources – planar wire arrays (PWAs). PWAs turned out to be a prolific radiator. Another success was the drastic improvement in energy efficiency of pulsed-power systems, such as the Load Current Multiplier (LCM). The Zebra/LCM generator almost doubled the plasma load current to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum design for ICF, as jointly proposed by SNL and UNR. Good agreement between simulated and measured radiation temperature of the central target is shown. Experimental comparison of PWAs with planar foil liners (PFL) - another viable alternative to wire array loads at multi-MA generators show promising data. Results of research at the University of Nevada Reno allowed for the study of hohlraum coupling physics at University-scale generators. The advantages of new hohlraum design applications for multi-MA facilities with W or Au double PWAs or PFL x-ray sources are discussed.

  14. A simple model of hohlraum power balance and mitigation of SRS

    DOE PAGES

    Albright, Brian J.; Montgomery, David S.; Yin, Lin; ...

    2016-04-01

    A simple energy balance model has been obtained for laser-plasma heating in indirect drive hohlraum plasma that allows rapid temperature scaling and evolution with parameters such as plasma density and composition. Furthermore, this model enables assessment of the effects on plasma temperature of, e.g., adding high-Z dopant to the gas fill or magnetic fields.

  15. Using VISAR to assess the M-band isotropy in hohlraums

    DOE PAGES

    Lanier, Nicholas Edward; Kline, John L.; Morton, John

    2016-09-27

    In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum’s actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF’s natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. Thesemore » experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.« less

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

    NASA Astrophysics Data System (ADS)

    Clark, Daniel; Weber, Christopher; Smalyuk, Vladimir; Robey, Harry; Kritcher, Andrea; Milovich, Jose; Salmonson, Jay

    2016-10-01

    Current indirect drive implosion experiments on the National Ignition Facility (NIF) 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. 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. A new symmetry model for hohlraum-driven capsule implosion experiments on the NIF

    NASA Astrophysics Data System (ADS)

    Jones, O.; Rygg, R.; Tomasini, R.; Eder, D.; Kritcher, A.; Milovich, J.; Peterson, L.; Thomas, C.; Barrios, M.; Benedetti, R.; Doeppner, T.; Ma, T.; Nagel, S.; Pak, A.; Field, J.; Izumi, N.; Glenn, S.; Town, R.; Bradley, D.

    2016-03-01

    We have developed a new model for predicting the time-dependent radiation drive asymmetry in laser-heated hohlraums. The model consists of integrated Hydra capsule-hohlraum calculations coupled to a separate model for calculating the crossbeam energy transfer between the inner and outer cones of the National Ignition Facility (NIF) indirect drive configuration. The time- dependent crossbeam transfer model parameters were adjusted in order to best match the P2 component of the shape of the inflight shell inferred from backlit radiographs of the capsule taken when the shell was at a radius of 150-250 μm. The adjusted model correctly predicts the observed inflight P2 and P4 components of the shape of the inflight shell, and also the P2 component of the shape of the hotspot inferred from x-ray self-emission images at the time of peak emission. It also correctly captures the scaling of the inflight P4 as the hohlraum length is varied. We then applied the newly benchmarked model to quantify the improved symmetry of the N130331 layered deuterium- tritium (DT) experiment in a re-optimized longer hohlraum.

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

    SciTech Connect

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

    2016-07-15

    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.

  19. Soft x-ray images of the laser entrance hole of ignition hohlraums

    SciTech Connect

    Schneider, M. B.; Meezan, N. B.; Alvarez, S. S.; Alameda, J.; Baker, S.; Bell, P. M.; Bradley, D. K.; Callahan, D. A.; Celeste, J. R.; Dewald, E. L.; Dixit, S. N.; Doeppner, T.; Eder, D. C.; Edwards, M. J.; Fernandez-Perea, M.; Hau-Riege, S.; Hsing, W.; Izumi, N.; Jones, O. S.; Kalantar, D. H.; and others

    2012-10-15

    Hohlraums are employed at the national ignition facility to convert laser energy into a thermal x-radiation drive, which implodes a fusion capsule, thus compressing the fuel. The x-radiation drive is measured with a low spectral resolution, time-resolved x-ray spectrometer, which views the region around the hohlraum's laser entrance hole. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the size of the hohlraum's opening ('clear aperture') and fraction of the measured x-radiation, which comes from this opening, must be known. The size of the clear aperture is measured with the time integrated static x-ray imager (SXI). A soft x-ray imaging channel has been added to the SXI to measure the fraction of x-radiation emitted from inside the clear aperture. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the peak of the x-ray spectrum of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.

  20. Long Duration Multi-hohlraum X-ray Sources for Eagle Nebula Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Kane, Jave; Heeter, Robert; Martinez, David; Casner, Alexis; Villette, Bruno; Mancini, Roberto; Pound, Marc

    2013-10-01

    A novel foam-filled multi-hohlraum long-duration x-ray source has been demonstrated at the Omega EP laser and used to obtain L-band spectra of photoionized Ti. A larger scale version of the source will be used in the Science on NIF Eagle Nebula experiments studying dynamic evolution of distinctive pillar and cometary structures in star-forming clouds, where the long duration and directionality of photoionizing radiation from nearby stars generates new classes of flows and instabilities. At NIF, a target representing an astrophysical molecular cloud will be placed several mm from an x-ray source lasting 40-100 ns. At EP, three hohlraums were illuminated in sequence with 3.3 kJ pulses lasting 6 ns, or 4.3 kJ pulses lasting 10 ns, generating 18 or 30 ns of x-ray output at 90-100 eV color temperature. Performance of the source was validated using the μ DMX and VSG spectrometers, ASBO VISAR, and x-ray pinhole imagery. The HYDRA code suggests the EP-scale source can also be shot at NIF with at least 10 kJ per hohlraum. The multi-hohlraum source concept has potential further application to hard x-ray sources, soft x-ray backlighters, and nonlinear ablative hydrodynamics. Prepared by LLNL under Contract DE-AC52-07NA27344. J. Kane supported by DOE OFES grant HEDLP LAB 11-583.

  1. Soft x-ray images of the laser entrance hole of ignition hohlraums.

    PubMed

    Schneider, M B; Meezan, N B; Alvarez, S S; Alameda, J; Baker, S; Bell, P M; Bradley, D K; Callahan, D A; Celeste, J R; Dewald, E L; Dixit, S N; Döppner, T; Eder, D C; Edwards, M J; Fernandez-Perea, M; Gullikson, E; Haugh, M J; Hau-Riege, S; Hsing, W; Izumi, N; Jones, O S; Kalantar, D H; Kilkenny, J D; Kline, J L; Kyrala, G A; Landen, O L; London, R A; MacGowan, B J; MacKinnon, A J; McCarville, T J; Milovich, J L; Mirkarimi, P; Moody, J D; Moore, A S; Myers, M D; Palma, E A; Palmer, N; Pivovaroff, M J; Ralph, J E; Robinson, J; Soufli, R; Suter, L J; Teruya, A T; Thomas, C A; Town, R P; Vernon, S P; Widmann, K; Young, B K

    2012-10-01

    Hohlraums are employed at the national ignition facility to convert laser energy into a thermal x-radiation drive, which implodes a fusion capsule, thus compressing the fuel. The x-radiation drive is measured with a low spectral resolution, time-resolved x-ray spectrometer, which views the region around the hohlraum's laser entrance hole. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the size of the hohlraum's opening ("clear aperture") and fraction of the measured x-radiation, which comes from this opening, must be known. The size of the clear aperture is measured with the time integrated static x-ray imager (SXI). A soft x-ray imaging channel has been added to the SXI to measure the fraction of x-radiation emitted from inside the clear aperture. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the peak of the x-ray spectrum of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.

  2. 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.

  3. New compact hohlraum configuration research at the 1.7 MA Z-pinch generator

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Chuvatin, A. S.; Rudakov, L. I.; Velikovich, A. L.; Shrestha, I. K.; Esaulov, A. A.; Safronova, A. S.; Shlyaptseva, V. V.; Osborne, G. C.; Astanovitsky, A. L.; Weller, M. E.; Stafford, A.; Schultz, K. A.; Cooper, M. C.; Cuneo, M. E.; Jones, B.; Vesey, R. A.

    2014-12-01

    A new compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources was experimentally demonstrated in a full configuration with a central target and tailored shine shields (to provide a symmetric temperature distribution on the target) at the 1.7 MA Zebra generator. This presentation reports on the joint success of two independent lines of research. One of these was the development of new sources - planar wire arrays (PWAs). PWAs turned out to be a prolific radiator. Another success was the drastic improvement in energy efficiency of pulsed-power systems, such as the Load Current Multiplier (LCM). The Zebra/LCM generator almost doubled the plasma load current to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum design for ICF, as jointly proposed by SNL and UNR. Good agreement between simulated and measured radiation temperature of the central target is shown. Experimental comparison of PWAs with planar foil liners (PFL) - another viable alternative to wire array loads at multi-MA generators show promising data. Results of research at the University of Nevada Reno allowed for the study of hohlraum coupling physics at University-scale generators. The advantages of new hohlraum design applications for multi-MA facilities with W or Au double PWAs or PFL x-ray sources are discussed.

  4. The Near Vacuum Hohlraum Campaign at the NIF: A New Approach

    NASA Astrophysics Data System (ADS)

    Le Pape, Sebastien

    2015-11-01

    Hohlraums filled with helium >1 mg/cc have been used with some success on the National Ignition Facility. However challenges remain due to significant backscatter level, supra-thermal electron production and difficulties in modeling implosion symmetry via Cross Beam Energy Transfer (CBET). Near Vacuum Hohlraum (NVH, filled with <0.1 mg/cc of helium) may provide a viable alternative with negligible laser plasma instabilities and high laser-to-hohlraum coupling. In this reduced laser-plasma interaction system, implosion symmetry is controlled through direct adjustment of the laser beam power balance rather than through CBET. A significant challenge in extending this platform to higher convergence designs is achieving adequate symmetry control of the drive throughout the pulse. This talk will summarize experimental campaigns exploring laser pulse duration and power limits in three hohlraum size scales and two capsule size scales. Experiments with small capsules have shown good symmetry control using laser cone fraction tuning at convergence ratio (CR) of 18x and 7ns pulses. Results from higher convergence (CR ~ 25x) cryogenic DT layered capsule implosions with ~ 9 ns pulses will be presented and implications for achieving conditions required for robust alpha heating with NVH driven implosions will be discussed. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  5. A Novel Spherical Hohlraum Design with Tetrahedral 4 Laser Entrance Holes and High Radiation Performance

    NASA Astrophysics Data System (ADS)

    Jing, Longfei; Huang, Yunbao; Jiang, Shaoen; Li, Haiyan; Huang, Tianxuan; Ding, Yongkun

    2016-10-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious CBET effect, spherical hohlraum with octahedral 6 LEHs and single laser ring cone is presented to achieve higher radiation symmetry during the fusion process. However, it has several potential problems such as the long run distance, smaller space is left for diagnose, and the assembly of centrally located capsule. In this paper, we investigate the radiation performance, i.e., radiation symmetry and drive temperature on the capsule in the spherical hohlraum with tetrahedral 4 LEHs and single laser ring cone, since there is more available space for laser disposition and diagnose. Then, such target is optimized on the laser beam pointing direction and shape sizes to achieve high radiation performance, or the radiation symmetry and drive temperature on the capsule. Finally, a novel spherical hohlraum with optimal laser beam pointing and shape size has been demonstrated to have almost similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and additional 133 KJ energy of 2MJ energy for fusion can be utilized).. This work was supportedby NSAF#U1430124, and NSFC#51375185, #51405177, #11475154.

  6. Structure and dynamics of plasma interfaces in laser-driven hohlraums

    NASA Astrophysics Data System (ADS)

    Li, C. K.; Sio, H.; Frenje, J. A.; Séguin, F. H.; Birkel, A.; Petrasso, R. D.; Wilks, S. C.; Amendt, P. A.; Remington, B. A.; Masson-Laborde, P.-E.; Laffite, S.; Tassin, V.; Betti, R.; Sanster, T. C.; Fitzsimmons, P.; Farrell, M.

    2016-10-01

    Understanding the structure and dynamics of plasma interfaces in laser-driven hohlraums is important because of their potential effects on capsule implosion dynamics. To that end, a series of experiments was performed to explore critical aspects of the hohlraum environment, with particular emphasis on the role of self-generated spontaneous electric and magnetic fields at plasma interfaces, including the interface between fill-gas and Au-blowoff. The charged fusion products (3-MeV DD protons and 14.7-MeV D3He protons generated in shock-driven, D3He filled backlighter capsule) pass through the subject hohlraum and form images on CR-39 nuclear track detectors, providing critical information. Important physics topics, including ion diffusive mix and Rayleigh-Taylor instabilities, will be studied to illuminate ion kinetic dynamics and hydrodynamic instability at plasma interfaces in laser-driven hohlraums. This work was supported in part by LLE, the U.S. DoE (NNSA, NLUF) and LLNL.

  7. A Novel Spherical Hohlraum Design with Tetrahedral 4 Laser Entrance Holes and High Radiation Performance

    NASA Astrophysics Data System (ADS)

    Huang, Yunbao; Jing, Longfei; Jiang, Shaoen

    2016-10-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious CBET, and LPI effect, spherical hohlraum with octahedral 6 LEHs and single laser ring cone is investigated and presented to achieve higher radiation symmetry during the fusion process. However, it has several potential problems such as the long run distance and the close distance between the spot and their closet LEH for the laser beams, smaller space is left for diagnose, and the assembly of centrally located capsule. In this paper, based on view-factor transportation model, we investigate the radiation symmetry and the drive temperature on the centrally located capsule in the spherical hohlraum with tetrahedral 4 LEHs and single laser ring cone, since there is more available space for laser disposition and diagnose. Then, such target is optimized on the laser beam pointing direction and shape sizes to achieve high radiation performance, or the radiation symmetry and drive temperature on the capsule. Finally, a novel spherical hohlraum with optimal laser beam pointing and shape size has been demonstrated to have almost similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and additional 133 KJ energy of 2MJ energy for fusion can be utilized).

  8. Use of External Magnetic Fields in Hohlraum Plasmas to Improve Laser-Coupling

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Albright, B. J.; Kline, J. L.; Yin, L.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.; MacDonald, M. J.

    2014-10-01

    Controlling laser plasma instabilities and beam propagation in hohlraum plasmas is important for achieving high-gain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense low-Z plasma to the dense high-Z hohlraum wall. This leads to weaker Landau damping and stronger growth of stimulated Raman scatter, and poorer laser transmission due to absorption in the cooler plasma. Magnetic insulation of the heat conducting electrons can occur when the Hall parameter ωceτei >> 1 , where ωce is the electron-cyclotron frequency, and τei is the electron-ion collision time. For NIF laser-plasma conditions, it is shown that a 10-T external magnetic field may substantially reduce cross-field transport and may increase coronal plasma temperatures, thus increasing linear Landau damping and mitigating SRS. We will present calculations and simulations supporting this concept, and will present initial results from Omega experiments using gas-filled hohlraums with external B-fields up to 10-T. Work performed under the auspices of DOE by LANL under Contract DE-AC52-06NA25396.

  9. Using VISAR to assess the M-band isotropy in hohlraums

    SciTech Connect

    Lanier, Nicholas Edward; Kline, John L.; Morton, John

    2016-09-27

    In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum’s actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF’s natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. These experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.

  10. Design of octahedral spherical hohlraum for CH Rev5 ignition capsule

    NASA Astrophysics Data System (ADS)

    Cao, Hui; Chen, Yao-Hua; Zhai, Chuanlei; Zheng, Chunyang; Lan, Ke

    2017-08-01

    In this paper, we design an octahedral spherical Au hohlraum for CH Rev5 ignition capsule [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)] by using the initial design method and two-dimensional (2D) simulations, and we investigate its laser entrance hole (LEH) closure and laser-plasma instabilities (LPI) by using a spherical hohlraum with two different-size LEHs via 2D simulations. The designed spherical hohlraum with RH=5 RC, RL=1.2 mm , and RL*=2 RL requires an ignition laser pulse of 1.92 MJ in energy and 670 TW in peak power, where RH, RC, RL, and RL* are radii of the spherical hohlraum, capsule, LEH, and the cylindrical LEH outer ring, respectively. From 2D simulations, the closure and opening up of LEH are clearly obtained. The LEH closure and its rate are strongly connected to the radiation pulse, while the LEH opening-up and its rate are strongly connected to the laser pulse. The smallest radius of LEH during closure is 0.6 mm before opening up, which leaves enough room for arranging the laser beams with a radius of 0.5 mm in our design. By using a post-process code for LPI, a relatively high stimulated Brillouin scattering fraction and a very low stimulated Raman scattering fraction are predicted, which may be due to the neglection of three-dimensional density gradients of the ablative flow along the laser transportation in 2D simulations. This work provides the energy and power references for the future ignition laser facility which uses octahedral spherical hohlraums as ignition targets.

  11. Experimental room temperature hohlraum performance study on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Ralph, J. E.; Strozzi, D.; Ma, T.; Moody, J. D.; Hinkel, D. E.; Callahan, D. A.; MacGowan, B. J.; Michel, P.; Kline, J. L.; Glenzer, S. H.; Albert, F.; Benedetti, L. R.; Divol, L.; MacKinnon, A. J.; Pak, A.; Rygg, J. R.; Schneider, M. B.; Town, R. P. J.; Widmann, K.; Hsing, W.; Edwards, M. J.

    2016-12-01

    Room temperature or "warm" (273 K) indirect drive hohlraum experiments have been conducted on the National Ignition Facility with laser energies up to 1.26 MJ and compared to similar cryogenic or "cryo" (˜20 K) experiments. Warm experiments use neopentane (C5H12) as the low pressure hohlraum fill gas instead of helium, and propane (C3H8) to replace the cryogenic DT or DHe3 capsule fill. The increased average Z of the hohlraum fill leads to increased inverse bremsstrahlung absorption and an overall hotter hohlraum plasma in simulations. The cross beam energy transfer (CBET) from outer laser beams (pointed toward the laser entrance hole) to inner beams (pointed at the equator) was inferred indirectly from measurements of Stimulated Raman Scattering (SRS). These experiments show that a similar hot spot self-emission shape can be produced with less CBET in warm hohlraums. The measured inner cone SRS reflectivity (as a fraction of incident power neglecting CBET) is ˜2.5 × less in warm than cryo shots with similar hot spot shapes, due to a less need for CBET. The measured outer-beam stimulated the Brillouin scattering power that was higher in the warm shots, leading to a ceiling on power to avoid the optics damage. These measurements also show that the CBET induced by the flow where the beams cross can be effectively mitigated by a 1.5 Å wavelength shift between the inner and outer beams. A smaller scale direct comparison indicates that warm shots give a more prolate implosion than cryo shots with the same wavelength shift and pulse shape. Finally, the peak radiation temperature was found to be between 5 and 7 eV higher in the warm than the corresponding cryo experiments after accounting for differences in backscatter.

  12. Hohlraum glint and laser pre-pulse detector for NIF experiments using velocity interferometer system for any reflector.

    PubMed

    Moody, J D; Clancy, T J; Frieders, G; Celliers, P M; Ralph, J; Turnbull, D P

    2014-11-01

    Laser pre-pulse and early-time laser reflection from the hohlraum wall onto the capsule (termed "glint") can cause capsule imprint and unwanted early-time shocks on indirect drive implosion experiments. In a minor modification to the existing velocity interferometer system for any reflector diagnostic on NIF a fast-response vacuum photodiode was added to detect this light. The measurements show evidence of laser pre-pulse and possible light reflection off the hohlraum wall and onto the capsule.

  13. Dynamics of a Z Pinch X Ray Source for Heating ICF Relevant Hohlraums to 120-160eV

    SciTech Connect

    SANFORD,THOMAS W. L.; OLSON,RICHARD E.; MOCK,RAYMOND CECIL; CHANDLER,GORDON A.; LEEPER,RAMON J.; NASH,THOMAS J.; RUGGLES,LAURENCE E.; SIMPSON,WALTER W.; STRUVE,KENNETH W.; PETERSON,D.L.; BOWERS,R.L.; MATUSKA,W.

    2000-07-10

    A z-pinch radiation source has been developed that generates 60 {+-} 20 KJ of x-rays with a peak power of 13 {+-} 4 TW through a 4-mm diameter axial aperture on the Z facility. The source has heated NIF (National Ignition Facility)-scale (6-mm diameter by 7-mm high) hohlraums to 122 {+-} 6 eV and reduced-scale (4-mm diameter by 4-mm high) hohlraums to 155 {+-} 8 eV -- providing environments suitable for indirect-drive ICF (Inertial Confinement Fusion) studies. Eulerian-RMHC (radiation-hydrodynamics code) simulations that take into account the development of the Rayleigh-Taylor instability in the r-z plane provide integrated calculations of the implosion, x-ray generation, and hohlraum heating, as well as estimates of wall motion and plasma fill within the hohlraums. Lagrangian-RMHC simulations suggest that the addition of a 6 mg/cm{sup 3} CH{sub 2} fill in the reduced-scale hohlraum decreases hohlraum inner-wall velocity by {approximately}40% with only a 3--5% decrease in peak temperature, in agreement with measurements.

  14. Progress towards a more predictive model for hohlraum radiation drive and symmetry

    NASA Astrophysics Data System (ADS)

    Jones, Ogden

    2016-10-01

    The high flux model (HFM) was first developed to match emission levels observed from Au spheres illuminated symmetrically at the UR-LLE OMEGA laser. It utilizes a modern non-LTE atomic physics model and an electron thermal flux limiter of 0.15 or a non-local electron transport model. Shortly thereafter, the HFM was also found to better match the radiation drive observed through the laser entrance hole of laser-heated vacuum hohlraums on the NIF. Subsequent capsule implosion experiments driven by hohlraums filled with 1-1.6 mg/cc of He, having case-to-capsule ratios of 2.6, and pulse lengths 15-20 ns have been characterized by relatively large amounts of laser backscatter losses (up to 18% of the input laser energy). They have also utilized cross beam energy transfer (CBET) to transfer power to the lasers depositing energy near the hohlraum waist. When the HFM is applied to these experiments, the hohlraum x-ray drive is over-predicted by 20-30% during peak laser power, and the drive symmetry cannot be matched without making ad hoc corrections. More recent experiments using hohlraum fills from 0-0.6 mg/cc He, case-to-capsule ratios 3-4, and pulse lengths 6-10 ns have little or no CBET or backscatter and are in better agreement with calculations using the HFM, although discrepancies remain. Uncertainties remaining in the computational models of emissivity, laser absorption, heat transport, etc. used in our hydrodynamic codes can significantly affect predictions. In this work we test various physically-plausible adjustments or alternatives to these models in order to find a more predictive model for radiation drive in the regime with little or no backscatter or CBET. We utilize measurements of the radiation drive, shape and trajectory of the imploding shell, shape of the stagnated hot spot, and bang time in capsule implosions and spectroscopic measurements of the hohlraum plasma conditions to compare against high resolution hydrodynamic calculations using the various

  15. Hybrid-PIC modeling of laser-plasma interactions and hot electron generation in gold hohlraum walls

    NASA Astrophysics Data System (ADS)

    Thoma, C.; Welch, D. R.; Clark, R. E.; Rose, D. V.; Golovkin, I. E.

    2017-06-01

    The walls of the hohlraum used in experiments at the national ignition facility are heated by laser beams with intensities ˜ 10 15 W/cm2, a wavelength of ˜ 1 / 3 μm, and pulse lengths on the order of a ns, with collisional absorption believed to be the primary heating mechanism. X-rays generated by the hot ablated plasma at the gold walls are then used to implode a target in the hohlraum interior. In addition to the collisional absorption of laser energy at the walls, non-linear laser-plasma interactions (LPI), such as stimulated Raman scattering and two plasmon decay, are believed to generate a population of supra-thermal electrons which, if present in the hohlraum, can have a deleterious effect on target implosion. We describe results of hohlraum modeling using a hybrid particle-in-cell code. To enable this work, new particle-based algorithms for a multiple-ion magneto-hydrodynamic (MHD) treatment, and a particle-based ray-tracing model were developed. The use of such hybrid methods relaxes the requirement to resolve the laser wavelength, and allows for relatively large-scale hohlraum simulations with a reasonable number of cells. But the non-linear effects which are believed to be the cause of hot electron generation can only be captured by fully kinetic simulations with good resolution of the laser wavelength. For this reason, we employ a two-tiered approach to hohlraum modeling. Large-scale simulations of the collisional absorption process can be conducted using the fast quasi-neutral MHD algorithm with fluid particle species. From these simulations, we can observe the time evolution of the hohlraum walls and characterize the density and temperature profiles. From these results, we can transition to smaller-scale highly resolved simulations using traditional kinetic particle-in-cell methods, from which we can fully model all of the non-linear laser-plasma interactions, as well as assess the details of the electron distribution function. We find that vacuum

  16. Three-dimensional modeling of capsule implosions in OMEGA tetrahedral hohlraums

    SciTech Connect

    Schnittman, J. D.; Craxton, R. S.

    2000-07-01

    Tetrahedral hohlraums have been proposed as a means for achieving the highly uniform implosions needed for ignition with inertial confinement fusion (ICF) [J. D. Schnittman and R. S. Craxton, Phys. Plasmas 3, 3786 (1996)]. Recent experiments on the OMEGA laser system have achieved good drive uniformity consistent with theoretical predictions [J. M. Wallace et al., Phys. Rev. Lett. 82, 3807 (1999)]. To better understand these experiments and future investigations of high-convergence ICF implosions, the three-dimensional (3-D) view-factor code BUTTERCUP has been expanded to model the time-dependent radiation transport in the hohlraum and the hydrodynamic implosion of the capsule. Additionally, a 3-D postprocessor has been written to simulate x-ray images of the imploded core. Despite BUTTERCUP's relative simplicity, its predictions for radiation drive temperatures, fusion yields, and core deformation show close agreement with experiment. (c) 2000 American Institute of Physics.

  17. Three-dimensional modeling of capsule implosions in OMEGA tetrahedral hohlraums

    NASA Astrophysics Data System (ADS)

    Schnittman, J. D.; Craxton, R. S.

    2000-07-01

    Tetrahedral hohlraums have been proposed as a means for achieving the highly uniform implosions needed for ignition with inertial confinement fusion (ICF) [J. D. Schnittman and R. S. Craxton, Phys. Plasmas 3, 3786 (1996)]. Recent experiments on the OMEGA laser system have achieved good drive uniformity consistent with theoretical predictions [J. M. Wallace et al., Phys. Rev. Lett. 82, 3807 (1999)]. To better understand these experiments and future investigations of high-convergence ICF implosions, the three-dimensional (3-D) view-factor code BUTTERCUP has been expanded to model the time-dependent radiation transport in the hohlraum and the hydrodynamic implosion of the capsule. Additionally, a 3-D postprocessor has been written to simulate x-ray images of the imploded core. Despite BUTTERCUP's relative simplicity, its predictions for radiation drive temperatures, fusion yields, and core deformation show close agreement with experiment.

  18. pF3D Simulations of SBS and SRS in NIF Hohlraum Experiments

    NASA Astrophysics Data System (ADS)

    Langer, Steven; Strozzi, David; Amendt, Peter; Chapman, Thomas; Hopkins, Laura; Kritcher, Andrea; Sepke, Scott

    2016-10-01

    We present simulations of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) for NIF experiments using high foot pulses in cylindrical hohlraums and for low foot pulses in rugby-shaped hohlraums. We use pF3D, a massively-parallel, paraxial-envelope laser plasma interaction code, with plasma profiles obtained from the radiation-hydrodynamics codes Lasnex and HYDRA. We compare the simulations to experimental data for SBS and SRS power and spectrum. We also show simulated SRS and SBS intensities at the target chamber wall and report the fraction of the backscattered light that passes through and misses the lenses. Work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. Release number LLNL-ABS-697482.

  19. Expectations for hohlraum environment driven by spatially compressed flying radiation case at intermediate currents

    SciTech Connect

    Bowers, R.L.; Brownell, J.H.; Rogers, H.H.

    1997-12-31

    The radiation environment produced by the magnetic implosion of a hot, low density plasma and its stagnation on an axial cushion (a Flying Radiation Case) is modeled using a two-dimensional radiation magnetohydrodynamic code and drive parameters for the PFZA-Z machine pulsed power machine. The authors consider the effects of instability growth in the plasma during the implosion, its reassembly on the cushion, and plasma interactions with shaped electrodes. The radiation environment within the pinch and in an axial side hohlraum are modeled. They also consider effects of the pinch on the side hohlraum. The computational approach has been successful in modeling the implosion and radiation output of Z-pinches on the Pegasus facility at Los Alamos National Laboratory, and on the Saturn and PFZA-Z machines at Sandia National Laboratories.

  20. Suprathermal Electrons Generated by the Two-Plasmon-Decay Instability in Gas-Filled Hohlraums

    SciTech Connect

    Regan, S P; Seka, W; Stoeckl, C; Glebov, V Y; Sangster, T C; Meyerhofer, D D; McCrory, R L; Meezan, N B; Suter, L J; Glenzer, S H; Strozzi, D J; Meeker, D; Williams, E A; Jones, O S; Callahan, D A; Rosen, M D; Landen, O L; Sorce, C; MacGowan, B J; Kruer, W L

    2008-06-03

    For the first time a burst of suprathermal electrons is observed from the exploding laser-entrance-hole window of gas-filled hohlraums driven with 13.5 kJ of 351-nm laser light. The two-plasmon-decay instability appears to produce up to 20 J of hot electrons with T{sub hot} {approx} 75 keV at early times and has a sharp laser-intensity threshold between 0.3 and 0.5 x 10{sup 15} W/cm{sup 2}. The observed threshold can be exploited to mitigate preheat by window hot electrons in ignition hohlraums for the National Ignition Facility and achieve high-density, high-pressure conditions in indirect drive implosions.

  1. A cylinder-to-sphere Fourier view factor model for azimuthal asymmetry studies in cylindrical hohlraums

    NASA Astrophysics Data System (ADS)

    Giorla, J.; Poggi, F.; Paillard, D.

    2002-01-01

    This work addresses the analytical calculation of the irradiation coming from a cylindrical surface to a spherical one. This exact solution of the x-ray transport equation allows one to connect the emitted and the received fluxes, expanded as Fourier modes, by coefficients called Fourier view factors. Such a calculation is well suited to a symmetry study in the Laser Megajoule configuration [P.-A. Holstein, M. André, M. Casanova et al., C. R. Acad. Sci. Paris 1, 693 (2000)] where a cylindrical hohlraum and a spherical capsule are irradiated. Indeed, this 60 quad laser system induces an azimuthal asymmetry of the hohlraum lighting depending on the laser focal spot size. Thus, the Fourier view factors allow one to express the modes of the capsule irradiation as functions of the elliptic spot dimensions.

  2. Fluorescence based imaging for M-band drive symmetry measurement in hohlraum

    NASA Astrophysics Data System (ADS)

    Li, Qi; Yao, Li; Jing, Longfei; Hu, Zhimin; Huang, Chengwu; Yuan, Zheng; Zhao, Yang; Xiong, Gang; Qing, Bo; Lv, Min; Zhu, Tuo; Deng, Bo; Li, Jin; Wei, Minxi; Zhan, Xiayu; Li, Jun; Yang, Yimeng; Su, Chunxiao; Yang, Guohong; Zhang, Jiyan; Li, Sanwei; Yang, Jiamin; Ding, Yongkun

    2016-11-01

    We describe an experimental technique to measure the drive symmetry of M-band radiation on the capsule in hohlraum. M-band radiation from the corona of the laser-produced gold plasma, especially the laser spot regions in the cavity, was used to pump x-ray fluorescence of a thin layer of Si-tracer coated on a solid CH-ball. The fluorescence images were time resolvedly recorded by an x-ray framing camera and the drive asymmetry due to M-band radiation was deduced from these fluorescence images. Moreover, a Si-doped gold cavity was used with the initial purpose of maximizing the fluorescence signal through resonance transitions. Since the Si-plasma expands more rapidly than the gold-plasma, the evolution of drive asymmetry was accelerated in Si-doped hohlraum.

  3. Development of a Two-shock, Vacuum Hohlraum, Plastic Capsule Implosion Experimental Platform on NIF

    NASA Astrophysics Data System (ADS)

    Salmonson, Jay; MacLaren, Stephen; Dittrich, Thomas; Ma, Tammy; Pino, Jesse; Tipton, Robert; Olson, Richard

    2014-10-01

    A new experimental platform has been developed to study a variety of indirect drive capsule implosion characteristics. A relatively small, ~1700 micron outer diameter, and thick, ~200 microns, uniformly Silicon doped, gas-filled plastic capsule is driven inside a standard size 5750 micron diameter ignition hohlraum. The hohlraum fill is near vacuum to reduce back-scatter and improve laser/drive coupling. A two-shock pulse of about ~1 MJ of laser energy drives the capsule. The thick capsule prevents ablation front feed-through to the imploded core. Compared to an NIF ignition experiment, this relatively simple, low laser energy platform will allow detailed studies, via sequences of shots, scanning implosion symmetry, capsule gas-fill and convergence, roughness and mix, as well as optimizing stagnation pressure. Recent experimental results toward commissioning this platform will be discussed. Prepared by LLNL under Contract DE-AC52-07NA27344.

  4. Interaction of high power laser beams with plasma in ICF hohlraum using the FDTD method

    NASA Astrophysics Data System (ADS)

    Lin, Zhili

    2016-11-01

    In the indirect-drive Inertial confinement fusion (ICF) system, groups of laser beams are injected into a gold cylindrical hohlraum and plasma is stimulated with the ablation of the wall of hohlraum by the laser beams. In our work, the finite-difference time-domain (FDTD) method associated with the bilinear transform and Maclaurin series expansion approaches is utilized to examine the laser beam propagation in plasma described by the Drude model. The state-of-the-art approaches for generating the laser beams are presented and realized according to the full utilization of the TF/SF source condition. Base on the previous technologies, the quantitatively numerical analysis of the propagation characteristics of laser beams in the plasma is conducted. The obtained results are illustrated and discussed that are helpful for the parameter optimization of laser beams for an ICF system.

  5. Study of shockwave method for diagnosing the radiation fields of laser-driven gold hohlraums

    NASA Astrophysics Data System (ADS)

    Li, Yongsheng; Lan, Ke; Huo, Wenyi; Lai, Dongxian; Gao, Yaoming; Pei, Wenbing

    2013-11-01

    Besides the routinely used broad-band x-ray spectrometer (Dante or SXS), ablative shock-wave method is often used to diagnose the radiation fields of laser-driven Hohlraums. The x-ray ablation process of Aluminum and Titanium is studied numerically with a 1-D radiation hydrodynamic code RDMG [F. Tinggui et al., Chin. J. Comput. Phys. 16, 199 (1999)], based on which a new scaling relation of the equivalent radiation temperature with the ablative shock velocity in Aluminum plates is proposed, and a novel method is developed for determining simultaneously the radiation temperature and the M-band (2-4 keV) fraction in laser-driven gold Hohlraums.

  6. Overview of the dynamic-hohlraum x-ray source at Sandia National Laboratories.

    SciTech Connect

    Sanford, Thomas W. L.

    2007-04-01

    Progress in understanding the physics of Dynamic-Hohlraums is reviewed for a system capable of generating 10 TW of axial radiation for high temperature (>200 eV) radiation-flow experiments and ICF capsule implosions. 2D magneto-hydrodynamic simulation comparisons with data show the need to include wire initiation physics and subsequent discrete wire dynamics in the simulations if a predictive capability is to be achieved.

  7. Planar hydrodynamic instability computations and experiments with rugby-shaped hohlraums at the Omega laser

    NASA Astrophysics Data System (ADS)

    Vandenboomgaerde, M.; Liberatore, S.; Galmiche, D.; Casner, A.; Huser, G.; Jadaud, J. P.; Villette, B.

    2008-05-01

    Implosion of inertial confinement fusion (ICF) capsule is very sensitive to the growth of sphericity perturbations. The control of the feeding of such perturbations and their transport ('feedthrough') through the ablator is a key point to reach ignition. Since 2002 [1, 2], experiments have been designed and performed on the Omega laser facility in order to study these phenomena in planar geometry. A new 'rugby shaped' hohlraum was used [3, 4]. We present experimental results and comparisons with numerical simulations.

  8. Demonstrated high performance of gas-filled rugby-shaped hohlraums on Omega

    NASA Astrophysics Data System (ADS)

    Philippe, F.; Tassin, V.; Depierreux, S.; Gauthier, P.; Masson-Laborde, P. E.; Monteil, M. C.; Seytor, P.; Villette, B.; Lasinski, B.; Park, H. S.; Ross, J. S.; Amendt, P.; Döppner, T.; Hinkel, D. E.; Wallace, R.; Williams, E.; Michel, P.; Frenje, J.; Gatu-Johnson, M.; Li, C. K.; Petrasso, R.; Glebov, V.; Sorce, C.; Stoeckl, C.; Nikroo, A.; Giraldez, E.

    2014-07-01

    A direct experimental comparison of rugby-shaped and cylindrical shaped gas-filled hohlraums on the Omega laser facility demonstrates that higher coupling and minimal backscatter can be achieved in the rugby geometry, leading to significantly enhanced implosion performance. A nearly 50% increase of x-ray drive is associated with earlier bangtime and increase of neutron production. The observed drive enhancement from rugby geometry in this study is almost twice stronger than in previously published results.

  9. The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

    NASA Astrophysics Data System (ADS)

    Ren, Guoli; Pei, Wenbing; Lan, Ke; Li, Xin; Hohlraum Physics Team

    2014-10-01

    In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum-number (n-level) average atom model (AAM) in NLTE plasma description. The more sophisticated atomic kinetics description is better choice, but the in-line calculation consumes much more resource. By distinguishing the much more fast bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to built up a bound electron distribution (n-level or nl-level) using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using this method and the plasma condition calculated under n-level, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures. Also we use this method in the benchmark gold sphere experiment, the constructed nl-level radiation drive resembles the experimental results and DCA results, while the n-level raditation does not.

  10. The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

    NASA Astrophysics Data System (ADS)

    Ren, Guoli; Pei, Wenbing; Lan, Ke; Gu, Peijun; Li, Xin; Institute of Applied Physics; Computional Mathematics Team

    2011-10-01

    In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum- number(n-level) average atom model(AAM). However, the experimental frequency-dependant radiative drive differs from our n-level simulated drive, which reminds us the need of a more detailed atomic kinetics description. The orbital-quantum-number(nl-level) AAM is a natural consideration but the in-line calculation consumes much more resources. We use a new method to built up a nl-level bound electron distribution using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using the re-built nl-level bound electron distribution (Pnl) , we acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures.

  11. Simulating hohlraum dynamics and radiation flow for Pleiades experiments on NIF

    NASA Astrophysics Data System (ADS)

    Mussack, K.; Devolder, B. G.; Keiter, P. A.; Kline, J. L.; Lanier, N.; Magelssen, G. R.; Peterson, R. R.; Taccetti, J. M.

    2011-10-01

    The Pleiades campaign is developing and validating an experimental platform on NIF to produce a high-quality radiation drive to study super-, trans- and subsonic radiation flow. Platform requirements include 5% shot-to-shot repeatability, a minimum radiation drive of 300 eV, and the ability to provide supersonic radiation. Here we discuss the ongoing series of experiments, focusing on simulations of the hohlraum and package. We assess the platform's ability to provide the required drive and reproducibility, the effectiveness of spectral tailoring with M-band absorbing foam, and the ability of our models to simulate the hohlraum drive and radiation flow. Early shots in the campaign have met or surpassed requirements. The first shot produced a 340 eV drive, exceeding the minimum drive requirement. The Dante-measured flux from the second shot demonstrated success in meeting the repeatability requirement. Simulated Dante temperatures match both shots well, indicating that simulations successfully model the laser energy deposition and hohlraum dynamics.

  12. The Evolution of the Gold Bubble in NIF Ignition Gas-Filled Hohlraums

    NASA Astrophysics Data System (ADS)

    Schneider, Marilyn; MacLaren, Steve; Widmann, Klaus; Meezan, Nathan; Hammer, James; Bell, Perry; Benedetti, Robin; Bradley, David; Callahan, Deborah; Dewald, Eduard; Doeppner, Tilo; Hinkel, Denise; Jones, Oggie; Landen, O. L.; Michel, Pierre; Milovich, Jose; Moody, John; Moore, Alastair

    2015-11-01

    At the National Ignition Facility (NIF), the energy from 192 laser beams is converted to an x-ray drive in a gas-filled gold hohlraum. The x-ray drive heats and implodes a fuel capsule. The ViewFactor platform uses a truncated hohlraum to measure the x-ray drive from the capsule point-of-view. This platform also affords excellent diagnostic views of the hohlraum interior, in particular, of the region in which the outer beams deposit their energy (the ``gold bubble'') Time-resolved and time-integrated images in the hard x-ray range (>3 keV) reveal an 8-fold symmetry in the gold bubble. The Au plasma in the bubble from the eight 50 degree quads expands faster than that from the interleaved 44.5 degree quads. The variation in this structure with laser intensity, with pulse shape and cross beam energy transfer, and comparison to models, will be discussed. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  13. Convergent ablation measurements with gas-filled rugby hohlraum on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Galmiche, D.

    2016-03-01

    Convergent ablation experiments with gas-filled rugby hohlraum were performed for the first time on the OMEGA laser facility. A time resolved 1D streaked radiography of capsule implosion is acquired in the direction perpendicular to hohlraum axis, whereas a 2D gated radiography is acquired at the same time along the hohlraum axis on a x-ray framing camera. The implosion trajectory has been measured for various kinds of uniformly doped ablators, including germanium-doped and silicon-doped polymers (CH), at two different doping fraction (2% and 4% at.). Our experiments aimed also at measuring the implosion performance of laminated capsules. A laminated ablator is constituted by thin alternate layers of un-doped and doped CH. It has been previously shown in planar geometry that laminated ablators could mitigate Rayleigh Taylor growth at ablation front. Our results confirm that the implosion of a capsule constituted with a uniform or laminated ablator behaves similarly, in accordance with post-shot simulations performed with the CEA hydrocode FCI2.

  14. Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums.

    PubMed

    Dewald, E L; Hartemann, F; Michel, P; Milovich, J; Hohenberger, M; Pak, A; Landen, O L; Divol, L; Robey, H F; Hurricane, O A; Döppner, T; Albert, F; Bachmann, B; Meezan, N B; MacKinnon, A J; Callahan, D; Edwards, M J

    2016-02-19

    In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10× higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

  15. Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums

    NASA Astrophysics Data System (ADS)

    Dewald, E. L.; Hartemann, F.; Michel, P.; Milovich, J.; Hohenberger, M.; Pak, A.; Landen, O. L.; Divol, L.; Robey, H. F.; Hurricane, O. A.; Döppner, T.; Albert, F.; Bachmann, B.; Meezan, N. B.; MacKinnon, A. J.; Callahan, D.; Edwards, M. J.

    2016-02-01

    In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10 × higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

  16. Early hot electrons generation and beaming in ICF gas filled hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Dewald, Eduard; Michel, Pierre; Hartemann, Fred; Milovich, Jose; Hohenberger, Matthias; Divol, Laurent; Landen, Otto; Pak, Arthur; Thomas, Cliff; Doeppner, Tilo; Bachmann, Benjamin; Meezan, Nathan; MacKinnon, Andrew; Hurricane, Omar; Callahan, Debbie; Hinkel, Denise; Edwards, John

    2015-11-01

    In laser driven hohlraum capsule implosions on the National Ignition Facility, supra-thermal hot electrons generated by laser plasma instabilities can preheat the capsule. Time resolved hot electron Bremsstrahlung spectra combined with 30 keV x-ray imaging uncover for the first time the directionality of hot electrons onto a high-Z surrogate capsule located at the hohlraum center. In the most extreme case, we observed a collimated beaming of hot electrons onto the capsule poles, reaching 50x higher localized energy deposition than for isotropic electrons. A collective SRS model where all laser beams in a cone drive a common plasma wave provides a physical interpretation for the observed beaming. Imaging data are used to distinguish between this mechanism and 2ωp instability. The amount of hot electrons generated can be controlled by the laser pulse shape and hohlraum plasma conditions. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  17. Diagnosis of ignition failure modes with 1 MJ capsule-Hohlraum designs

    NASA Astrophysics Data System (ADS)

    Bradley, P. A.; Wilson, D. C.; Delamater, N. D.; Douglas, M. R.

    2006-10-01

    At Los Alamos, we have been working on two-dimensional capsule-Hohlraum implosion calculations for the NIF that utilize a laser drive pulse that peaks at ˜300eV and uses about 1MJ of laser energy. We use a 0.3at.% uniformly Cu doped beryllium ablator capsule that has an inner ice radius of 753μm, inner ablator radius of 825μm, and an outer ablator radius of 1000μm. Our Hohlraum has a diameter of 5.02mm and a length of 8.56mm. We use a Hohlraum gas fill density of 1.3mg/cm3 and obtain ignition with yields up to 9.8MJ, but we also have some failures due to bad shock timing or different pointing positions of the inner and outer laser cones. We describe the salient features of our implosions and show postprocessed diagnostic signatures from x-ray and neutron images, along with reaction history plots to show how we can diagnose "failures" and how to correct for them based on these diagnostics.

  18. Neutron reactions in the hohlraum at the LLNL National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Bradley, P. A.; Grim, G. P.; Hayes, A. C.; Jungman, Gerard; Rundberg, R. S.; Wilhelmy, J. B.; Hale, G. M.; Korzekwa, R. C.

    2012-07-01

    The National Ignition Facility (NIF) is designed to drive deuterium-tritium (DT) inertial confinement fusion targets to ignition using indirect radiation from laser energy captured in a hohlraum. The projected yields at NIF suggest that interactions of neutrons with the hohlraum can directly probe the neutron spectrum. Different physical parameters of the burning capsule can be probed by different neutron reactions. We suggest a variety of neutron reactions on the gold and uranium present in National Ignition Campaign hohlraums that will be useful for both neutron diagnostics and dosimetry at the NIF. The radiochemical daughter products may then be used to infer the neutron spectrum from the capsule. The downscattered neutrons may be studied by the (n,γ) and (n,n') reactions to infer the areal density of the capsule. The 14 MeV neutron fluence may be measured by (n,2n) daughter products for comparison to neutron spectrometer data. The hydrodynamical mix in the capsule can be studied with RIF neutrons, which are probed by (n,3n) reactions.

  19. Near-vacuum hohlraums with uranium walls for driving high density carbon ablators

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.; Dewald, E. L.; Berzak Hopkins, L. F.; Moore, A. S.; Schneider, M. V.; Thomas, C. A.; Tommasini, R.; Ho, D. D.; Clark, D. S.; Weber, C. R.; Hamza, A. V.; Nikroo, A.; Le Pape, S.; Divol, L.; MacKinnon, A. J.

    2015-11-01

    We present experimental results for unlined uranium near-vacuum hohlraums on the National Ignition Facility. X-ray wall losses are lower in uranium than in gold at radiation temperatures near 300 eV. In addition, the intensity of x-rays with energy hν > 1 . 8 keV is lower for uranium hohlraums. The softer uranium spectrum allows the use of ablators with lower levels of dopants that reduce rocket efficiency and increase the risk of polluting the hot-spot with emissive material. Experiments in the ViewFactor platform measured 5% higher total x-ray intensity and 30% lower intensity of hν > 1 . 8 keV for uranium relative to gold. Back-lit implosions using undoped high-density carbon (HDC, or diamond) capsules achieved a velocity of 400 +/- 20 km/s compared to 360 +/- 20 km/s for gold. These results have led the NIF HDC campaign to baseline uranium hohlraums for upcoming experiments. Prepared by LLNL under Contract DE-AC52-07NA27344.

  20. Development of short pulse laser driven micro-hohlraums as a source of EUV radiation

    NASA Astrophysics Data System (ADS)

    Krushelnick, Karl; Batson, Thomas; McKelvey, Andrew; Raymond, Anthony; Thomas, Alec; Yanovsky, Victor; Nees, John; Maksimchuk, Anatoly

    2015-11-01

    Experiments at large scale laser facilities such as NIF allow the radiativ properties of dens, high-temperature matter to be studied at previously unreachable regime, but are limited by cost and system availability. A scaled system using a short laser pulses and delivering energy to much smaller hohlraum could be capable of reaching comparable energy densities by depositing the energy in a much smaller volume before ablation of the wall material closes the cavit. The laser is tightl focused through the cavity and then expands to illuminate the wall. Experiments were performe using the Hercules Ti:Sapphire laser system at Michiga. Targets include cavities machined in bulk material using low laser power, and then shot in situ with a single full power pulse as well as micron scale pre-fabricate target. Spectral characteristics were measured using a soft X-ray spectromete, K-alpha x-ray imaging system and a filtered photo cathode array. Scalings of the radiation temperature were made for variations in the hohlraum cavit, the pulse duration as well as the focusing conditions. Proof of principle time resolved absorption spectroscopy experiments were also performe. These sources may allow opacity and atomic physics measurements with plasma an radiation temperatures comparable to much larger hohlraums, but with much higher repetition rate and in a university scale laboratory. We acknowledge funding from DTRA grant HDTRA1-11-1-0066.

  1. Hohlraum Target Alignment from X-ray Detector Images using Starburst Design Patterns

    SciTech Connect

    Leach, R R; Conder, A; Edwards, O; Kroll, J; Kozioziemski, B; Mapoles, E; McGuigan, D; Wilhelmsen, K

    2010-12-14

    National Ignition Facility (NIF) is a high-energy laser facility comprised of 192 laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to initiate a fusion reaction. The target container, or hohlraum, must be accurately aligned to an x-ray imaging system to allow careful monitoring of the frozen fuel layer in the target. To achieve alignment, x-ray images are acquired through starburst-shaped windows cut into opposite sides of the hohlraum. When the hohlraum is in alignment, the starburst pattern pairs match nearly exactly and allow a clear view of the ice layer formation on the edge of the target capsule. During the alignment process, x-ray image analysis is applied to determine the direction and magnitude of adjustment required. X-ray detector and source are moved in concert during the alignment process. The automated pointing alignment system described here is both accurate and efficient. In this paper, we describe the control and associated image processing that enables automation of the starburst pointing alignment.

  2. The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Schneider, M. B.; MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Dewald, E. L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Guymer, T. M.; Hinkel, D. E.; Hohenberger, M.; Hsing, W. W.; Kervin, M. L.; Kilkenny, J. D.; Landen, O. L.; Lindl, J. D.; May, M. J.; Michel, P.; Milovich, J. L.; Moody, J. D.; Moore, A. S.; Ralph, J. E.; Regan, S. P.; Thomas, C. A.; Wan, A. S.

    2015-12-01

    At the National Ignition Facility, a thermal X-ray drive is created by laser energy from 192 beams heating the inside walls of a gold cylinder called a "hohlraum." The x-ray drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH radius decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma from the high-intensity region in the center of the LEH pushing radially outward. The x-ray drive on the capsule is deduced by measuring the time evolution and spectra of the x-radiation coming out of the LEH and correcting for geometry and for the radius of the LEH. Previously, the LEH radius was measured using time-integrated images in an x-ray band of 3-5 keV (outside the thermal x-ray region). For gas-filled hohlraums, the measurements showed that the LEH radius is larger than that predicted by the standard High Flux radiation-hydrodynamic model by about 10%. A new platform using a truncated hohlraum ("ViewFactor hohlraum") is described, which allows time-resolved measurements of the LEH radius at thermal x-ray energies from two views, from outside the hohlraum and from inside the hohlraum. These measurements show that the LEH radius closes during the low power part of the pulse but opens up again at peak power. The LEH radius at peak power is larger than that predicted by the models by about 15%-20% and does not change very much with time. In addition, time-resolved images in a >4 keV (non-thermal) x-ray band show a ring of hot, optically thin gold plasma just inside the optically thick LEH plasma. The structure of this plasma varies with time and with Cross Beam Energy Transfer.

  3. The first measurements of soft x-ray flux from ignition scale Hohlraums at the national ignition facility using DANTE

    SciTech Connect

    Kline, John L; Glenzer, S H; Olson, Rick; Suter, Larry J; Widmann, K; Callahan, D A; Dixit, S N; Thomas, C A; Hinkel, D E; Williams, E A; Moore, A; Celeste, J; Dewald, E; Hsing, W W; Warrick, A; Atherton, J; Azevedo, S; Beeler, R; Berger, R; Conder, A; Divol, L; Haynam, C A; Kalantar, D H; Kauffman, R; Kilkenny, J; Liebman, J; Larson, D; Meezan, N B; Michel, P; Moody, J; Rosen, M D; Schneider, M B; Van Wontergheman, B; Wallace, R J; Young, B K; Landen, O L; MacGowan, B J; Berzins, L; Tran, Vu; Torres, P., III

    2010-01-01

    The first 96 and 192 beam vacuum hohlraum have been fielded at the National Ignition Facility demonstrating radiation temperatures up to 340 eV and fluxes of 20 TW/sr representing a 20 times flux increase over NOVA/Omega scale hohlraums. The vacuum hohlraums were irradiated with 2 ns square pulses with energies between 150 - 635 kJ. They produced nearly Planckian spectra with about 30 {+-} 10% more flux than predicted by the current radiation hydrodynamic simulations after careful verification of all component calibrations (which included an {approx} 10% downward correction to Center X-Ray Optics opacities just below the Cu L edge at 50-750 eV), cable deconvolution, and analysis software routines. To corroborate these results, first a half hohlraum experiment was conducted using a single 2 ns-long axial quad with an irradiance of {approx} 1-2 x 10{sup 15} W/cm{sup 2} for comparison with NIF Early Light experiments completed in 2004. Second, we completed a conversion efficiency test using a 128-beam nearly uniformly illuminated gold sphere with intensities kept low (at 1 x 10{sup 14} W/cm{sup 2} over 5 ns) to avoid sensitivity to modeling uncertainties for non-local heat conduction and non-linear absorption mechanisms, to compare with similar intensity, 3 ns OMEGA sphere results. The 2004 and 2009 NIF half-hohlraums agreed to 10% in flux, but more importantly, the 2006 OMEGA Au Sphere, the 2009 NIF Au sphere and the calculated Au conversion efficiency agree to {+-}5% in flux, which is estimated to be the absolute calibration accuracy of the DANTEs. Hence we concluded the 30 {+-} 10% higher than expected radiation fluxes from the 96 and 192 beam vacuum hohlraums are attributable to differences in physics when we transitioned to large hot hohlraums. Specifically, using variants in the atomic physics models and electron heat conduction, newer simulations show that nonlocalization of energy deposition leads to less energy being stored in the coronal plasma leading to

  4. Hydro-Coupling Effects on Compression Symmetry in Gas-Filled Hohlraum Experiments at the Omega Laser

    SciTech Connect

    Dewalds, E L; Pollaine, S W; Landen, O L; Amendt, P A; Turner, R E; Wallace, R; Campbell, K M; Glenzer, S H

    2003-08-26

    Ignition hohlraum designs use low Z gas fill to slow down the inward progress of high Z ablated plasma from the hohlraum walls preventing large laser spot motion and capsule drive asymmetries. In order to optimize the ignition design, the gas hydro-coupling effect to a fusion capsule asymmetry is presently being assessed in experiments at the Omega laser facility with gas filled hohlraums and foam balls. Our experiments measure the effects of the pressure spike that is generated by direct gas heating by the drive laser beams on the capsule surrogate for various hohlraum gas fill densities (0-2.5 mg/cc). To isolate the effect of the gas-hydro coupling pressure, we have begun by using plastic ''hohlraums'' to reduce the x-ray ablation pressure. The foam ball images measured by x-ray backlighting show increasing pole-hot pressure asymmetry for increasing gas pressure. In addition, the gas hydrodynamics is studied by imaging of a low concentration Xe gas fill dopant. The gas fill self-emission. shows the early pressure spike and its propagation towards the foam ball, as well as the gas stagnation on the holraum axis at later times, both contributing to the capsule asymmetry. These first gas hydro-coupling results are compared to LASNEX simulations.

  5. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

    NASA Astrophysics Data System (ADS)

    Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J.

    2015-12-01

    Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.

  6. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

    SciTech Connect

    Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J.

    2015-12-15

    Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.

  7. Experimental demonstration of low laser-plasma instabilities in gas-filled spherical hohlraums at laser injection angle designed for ignition target

    NASA Astrophysics Data System (ADS)

    Lan, Ke; Li, Zhichao; Xie, Xufei; Chen, Yao-Hua; Zheng, Chunyang; Zhai, Chuanlei; Hao, Liang; Yang, Dong; Huo, Wen Yi; Ren, Guoli; Peng, Xiaoshi; Xu, Tao; Li, Yulong; Li, Sanwei; Yang, Zhiwen; Guo, Liang; Hou, Lifei; Liu, Yonggang; Wei, Huiyue; Liu, Xiangming; Cha, Weiyi; Jiang, Xiaohua; Mei, Yu; Li, Yukun; Deng, Keli; Yuan, Zheng; Zhan, Xiayu; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Deng, Xuewei; Liu, Jie; Du, Kai; Ding, Yongkun; Wei, Xiaofeng; Zheng, Wanguo; Chen, Xiaodong; Campbell, E. M.; He, Xian-Tu

    2017-03-01

    Octahedral spherical hohlraums with a single laser ring at an injection angle of 55∘ are attractive concepts for laser indirect drive due to the potential for achieving the x-ray drive symmetry required for high convergence implosions. Laser-plasma instabilities, however, are a concern given the long laser propagation path in such hohlraums. Significant stimulated Raman scattering has been observed in cylindrical hohlraums with similar laser propagation paths during the ignition campaign on the National Ignition Facility (NIF). In this Rapid Communication, experiments demonstrating low levels of laser-driven plasma instability (LPI) in spherical hohlraums with a laser injection angle of 55∘ are reported and compared to that observed with cylindrical hohlraums with injection angles of 28 .5∘ and 55∘, similar to that of the NIF. Significant LPI is observed with the laser injection of 28 .5∘ in the cylindrical hohlraum where the propagation path is similar to the 55∘ injection angle for the spherical hohlraum. The experiments are performed on the SGIII laser facility with a total 0.35 -μ m incident energy of 93 kJ in a 3 nsec pulse. These experiments demonstrate the role of hohlraum geometry in LPI and demonstrate the need for systematic experiments for choosing the optimal configuration for ignition studies with indirect drive inertial confinement fusion.

  8. Experimental demonstration of low laser-plasma instabilities in gas-filled spherical hohlraums at laser injection angle designed for ignition target.

    PubMed

    Lan, Ke; Li, Zhichao; Xie, Xufei; Chen, Yao-Hua; Zheng, Chunyang; Zhai, Chuanlei; Hao, Liang; Yang, Dong; Huo, Wen Yi; Ren, Guoli; Peng, Xiaoshi; Xu, Tao; Li, Yulong; Li, Sanwei; Yang, Zhiwen; Guo, Liang; Hou, Lifei; Liu, Yonggang; Wei, Huiyue; Liu, Xiangming; Cha, Weiyi; Jiang, Xiaohua; Mei, Yu; Li, Yukun; Deng, Keli; Yuan, Zheng; Zhan, Xiayu; Zhang, Haijun; Jiang, Baibin; Zhang, Wei; Deng, Xuewei; Liu, Jie; Du, Kai; Ding, Yongkun; Wei, Xiaofeng; Zheng, Wanguo; Chen, Xiaodong; Campbell, E M; He, Xian-Tu

    2017-03-01

    Octahedral spherical hohlraums with a single laser ring at an injection angle of 55^{∘} are attractive concepts for laser indirect drive due to the potential for achieving the x-ray drive symmetry required for high convergence implosions. Laser-plasma instabilities, however, are a concern given the long laser propagation path in such hohlraums. Significant stimulated Raman scattering has been observed in cylindrical hohlraums with similar laser propagation paths during the ignition campaign on the National Ignition Facility (NIF). In this Rapid Communication, experiments demonstrating low levels of laser-driven plasma instability (LPI) in spherical hohlraums with a laser injection angle of 55^{∘} are reported and compared to that observed with cylindrical hohlraums with injection angles of 28.5^{∘} and 55^{∘}, similar to that of the NIF. Significant LPI is observed with the laser injection of 28.5^{∘} in the cylindrical hohlraum where the propagation path is similar to the 55^{∘} injection angle for the spherical hohlraum. The experiments are performed on the SGIII laser facility with a total 0.35-μm incident energy of 93 kJ in a 3 nsec pulse. These experiments demonstrate the role of hohlraum geometry in LPI and demonstrate the need for systematic experiments for choosing the optimal configuration for ignition studies with indirect drive inertial confinement fusion.

  9. Performance of beryllium targets with full-scale capsules in low-fill 6.72-mm hohlraums on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Simakov, A. N.; Wilson, D. C.; Yi, S. A.; Loomis, E. N.; Kline, J. L.; Kyrala, G. A.; Zylstra, A. B.; Dewald, E. L.; Tommasini, R.; Ralph, J. E.; Strozzi, D. J.; MacPhee, A. G.; Milovich, J. L.; Rygg, J. R.; Khan, S. F.; Ma, T.; Jarrott, L. C.; Haan, S. W.; Celliers, P. M.; Marinak, M. M.; Rinderknecht, H. G.; Robey, H. F.; Salmonson, J. D.; Stadermann, M.; Baxamusa, S.; Alford, C.; Wang, Y.; Nikroo, A.; Rice, N.; Kong, C.; Jaquez, J.; Mauldin, M.; Youngblood, K. P.; Xu, H.; Huang, H.; Sio, H.

    2017-05-01

    When used with 1.06-mm beryllium (Be) capsules on the National Ignition Facility, gold hohlraums with the inner diameter of 5.75 mm and helium gas fill density of 1.6 mg/cm3 exhibit significant drive degradation due to laser energy backscatter (of order 14%-17%) and "missing" X-ray drive energy (about 32% during the main pulse). Also, hard to simulate cross-beam energy transfer (CBET) must be used to control the implosion symmetry. Larger, 6.72-mm hohlraums with fill densities ≤0.6 mg/cm3 generally offer improved drive efficiency, reduced hot-electron preheat, and better control of the implosion symmetry without CBET. Recently, we carried out an exploratory campaign to evaluate performance of 1.06-mm Be capsules in such hohlraums and determine optimal hohlraum parameters. Specifically, we performed a hohlraum fill-density scan with a three-shock, 9.5-ns laser pulse and found that an appropriate axial laser repointing and azimuthal outer-quad splitting resulted in significantly improved hohlraum energetics at fill densities ≤0.3 mg/cm3 (with backscattered and "missing" energies being of about 5% and 23% of the total laser energy, respectively). The capsule shape at stagnation was slightly oblate and improved with lowering the fill density. We also performed an implosion with a lower-picket, 12.6-ns pulse at the hohlraum fill density of 0.15 mg/cm3 to observe comparable hohlraum energetics (about 3% of backscattered and 27% of "missing" energy) but an even more oblate implosion shape. Thus, achieving symmetric implosions of 1.06-mm Be capsules in low-fill, 6.72-mm gold hohlraums with reasonably low-adiabat pulses may not be feasible. However, symmetric implosions have recently been successfully demonstrated in such hohlraums with 0.8-mm Be capsules.

  10. Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

    NASA Astrophysics Data System (ADS)

    Amendt, Peter

    2006-10-01

    The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) [1] targets as a complementary path to the baseline cryogenic single-shell approach [2]. Benefits of DS targets include room-temperature deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma-mediated laser backscatter, low threshold-ignition temperatures (4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances [3], and loose shock timing requirements. On the other hand, DS ignition presents several challenges, including room-temperature containment of high-pressure DT (790 atm) in the inner shell; strict concentricity requirements on the two shells; development of nanoporous, low-density, metallic foams for structural support of the inner shell and hydrodynamic instability mitigation; and effective control of perturbation growth on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition target designs using vacuum hohlraums is described, offering the potential for low levels of laser backscatter from stimulated Raman and Brillouin processes. In addition, vacuum hohlraums have the operational advantages of room temperature fielding and fabrication simplicity, as well as benefiting from extensive benchmarking on the Nova and Omega laser facilities. As an alternative to standard cylindrical hohlraums, a rugby-shaped geometry is also introduced that may provide energetics and symmetry tuning benefits for more robust DS designs with yields exceeding 10 MJ for 2 MJ of 3w laser energy. The recent progress in hohlraum designs and required advanced materials development are scheduled to culminate in a prototype demonstration of a NIF-scale ignition-ready DS in 2007. [1] P. Amendt et al., PoP 9, 2221 (2002). [2] J.D. Lindl et al., PoP 11, 339 (2004). [3] M.N. Chizhkov et al., Laser Part. Beams 23, 261 (2005). In collaboration with C. Cerjan, A. Hamza, J. Milovich and H. Robey.

  11. The influence of laser clipped by the laser entrance hole on hohlraum radiation measurement on Shenguang-III prototype

    SciTech Connect

    Yang, Dong; Li, Zhichao; Guo, Liang; Li, Sanwei; Yi, Rongqing; Song, Tianming; Zhang, Huan; Wang, Zhebin; Jiang, Xiaohua; Jiang, Shaoen; Ding, Yongkun

    2014-03-15

    Measuring the x-ray flux exiting the target's laser entrance hole (LEH) is the most common diagnostic that quantifies the x-ray intensity inside the laser-driven hohlraum. However, this signal accounts for only a small portion of the incident laser power and thus is likely to be affected by unwanted x-ray background from non-target area, leading to an overestimation of the hohlraum drive. Unwanted emission might be produced when the laser light is clipped by the LEH (LEH clipping) because of a lack of clearance for laser spot, or with a laser spot comprising of discrete structure, or even with a poor pointing accuracy. Its influence on the hohlraum radiation diagnostic is investigated on Shenguang-III prototype laser facility with the typical 1 ns square pulse. The experiment employed three types of targets to excite the unwanted x-ray background from LEH clipping, unconverted light, and both effects, respectively. This work gives an absolute evaluation of x-ray produced by the LEH clipping, which is measured by flat-response x-ray detectors (FXRD) at multiple view angles. The result indicates that there is little variation in measured emission to various view angles, because the unwanted x-rays are mainly generated at the side face of the LEH lip when laser is obliquely incident. Therefore, the LEH clipping brings more overestimation in hohlraum radiation measurement at larger view angle since the hohlraum LEH as an emitting source viewed by FXRD is decreased as the view angle increases. In our condition, the LEH clipping contributes 2%–3.5% overestimation to the hohlraum flux measurement.

  12. Simulation of self-generated magnetic fields in an inertial fusion hohlraum environment

    NASA Astrophysics Data System (ADS)

    Farmer, W. A.; Koning, J. M.; Strozzi, D. J.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O. S.; Rosen, M. D.

    2017-05-01

    We present radiation-hydrodynamic simulations of self-generated magnetic field in a hohlraum, which show an increased temperature in large regions of the underdense fill. Non-parallel gradients in electron density and temperature in a laser-heated plasma give rise to a self-generated field by the "Biermann battery" mechanism. Here, HYDRA simulations of three hohlraum designs on the National Ignition Facility are reported, which use a partial magnetohydrodynamic (MHD) description that includes the self-generated source term, resistive dissipation, and advection of the field due to both the plasma flow and the Nernst term. Anisotropic electron heat conduction parallel and perpendicular to the field is included, but not the Righi-Leduc heat flux. The field strength is too small to compete significantly with plasma pressure, but affects plasma conditions by reducing electron heat conduction perpendicular to the field. Significant reductions in heat flux can occur, especially for high Z plasma, at modest values of the Hall parameter, Ωeτei≲1 , where Ωe=e B /mec and τei is the electron-ion collision time. The inclusion of MHD in the simulations leads to 1 keV hotter electron temperatures in the laser entrance hole and high-Z wall blowoff, which reduces inverse-bremsstrahlung absorption of the laser beam. This improves propagation of the inner beams pointed at the hohlraum equator, resulting in a symmetry shift of the resulting capsule implosion towards a more prolate shape. The time of peak x-ray production in the capsule shifts later by only 70 ps (within experimental uncertainty), but a decomposition of the hotspot shape into Legendre moments indicates a shift of P2/P0 by ˜20 % . This indicates that MHD cannot explain why simulated x-ray drive exceeds measured levels, but may be partially responsible for failures to correctly model the symmetry.

  13. Scattered and Reflected Light Polarimetry as a Diagnostic of Multibeam Hohlraum Physics

    NASA Astrophysics Data System (ADS)

    Turnbull, David

    2015-11-01

    Scattered light provides a window into the complex laser-plasma interactions and hydrodynamics occurring within indirect-drive inertial confinement fusion (ICF) hohlraums. Understanding hohlraum physics is an important part of developing improved targets and increasing the likelihood of ignition. Measurements of the scattered light power and spectrum are routinely made on each cone of beams at the National Ignition Facility (NIF) in order to correct for coupling losses due to laser-plasma instabilities. The additional ability to probe scattered light polarization on a 30° incidence beam was recently added, which has produced a number of discoveries regarding multibeam hohlraum physics. One particularly important insight is that the polarizations of an incident beam and its backscatter are affected by amplitude and phase modulations induced by crossing laser beams. The revised theory describing this optical wave mixing has recently been validated by conducting a two beam pump-probe experiment under carefully controlled conditions. This effect could be utilized more generally to produce ultrafast, damage-resistant, and tunable laser-plasma wave plates, polarizers, or other photonic devices. It also enables remote polarimetry-based probing of plasma conditions such as electron temperature. To extract more quantitative feedback about crossed-beam energy transfer (CBET) from the polarimetry data in ICF experiments at the NIF, the diagnostic has been upgraded to measure the complete Stokes vector with temporal resolution. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  14. Measurement of the absolute hohlraum wall albedo under ignition foot drive conditions

    SciTech Connect

    Suter, L J; Wallace, R J; Hammel, B A; Weber, F A; Landen, O L; Campbell, K M; DeWald, E L; Glenzer, S H; Rosen, M D; Jones, O S; Turner, R E; Kauffmann, R L; Hammer, J H

    2003-11-25

    We present the first measurements of the absolute albedos of hohlraums made from gold or from high-Z mixtures. The measurements are performed over the range of radiation temperatures (70-100 eV) expected during the foot of an indirect-drive temporally-shaped ignition laser pulse, where accurate knowledge of the wall albedo (i.e. soft x-ray wall re-emission) is most critical for determining capsule radiation symmetry. We find that the gold albedo agrees well with calculations using the super transition array opacity model, potentially providing additional margin for ICF ignition.

  15. Experimental basis for laser-plasma interactions in ignition hohlraums at the National Ignition Facility

    SciTech Connect

    Froula, D H; Divol, L; London, R A; Berger, R L; Doeppner, T; Meezan, N B; Ralph, J; Ross, J S; Suter, L J; Glenzer, S H

    2009-11-12

    A series of laser plasma interaction experiments at OMEGA (LLE, Rochester) using gas-filled hohlraums shed light on the behavior of stimulated Raman scattering and stimulated Brillouin scattering at various plasma conditions encountered in indirect drive ignition designs. We present detailed experimental results that quantify the density, temperature, and intensity thresholds for both of these instabilities. In addition to controlling plasma parameters, the National Ignition Campaign relies on optical beam smoothing techniques to mitigate backscatter. We show that polarization smoothing is effective at controlling backscatter. These results provide an experimental basis for forthcoming experiments on National Ignition Facility.

  16. Preliminary characterization of ultra-short pulse laser-produced miniature hohlraum XUV sources

    NASA Astrophysics Data System (ADS)

    McKelvey, A.; Vargas, M.; Montier, L.; Nees, J.; Hou, B.; Maksimchuk, A.; Thomas, A. G. R.; Krushelnick, K.

    2012-10-01

    Experiments at the National Ignition Facility (NIF) allow the radiative properties of dense, high-temperature matter to be studied at previously unreachable regimes, but are limited by cost and system availability. A scaled down system using ultra-short laser pulses and delivering energy to a much smaller hohlraum could be capable of reaching comparable energy densities and depositing the energy before the wall material ablation closes the cavity. The Lambda Cubed laser system at University of Michigan--a high-power (0.3 TW), short pulse (30fs), 500 Hz repetition rate tabletop laser system-is used to machine 20-100 micron diameter cavities in copper targets. These cavities are machined with low laser powers, and then shot in situ with a single full power pulse. The emitted radiation is analyzed with an XUV spectrometer. This method may allow studies such as opacity measurements using plasma and radiation with the temperatures comparable to NIF type hohlraums, but with a significantly higher repetition rate and in a university scale system.

  17. Preliminary investigation on the radiation transfer in dynamic hohlraums on the PTS facility

    NASA Astrophysics Data System (ADS)

    Xiao, Delong; Ye, Fan; Meng, Shijian; Ning, Jiamin; Qin, Yi; Hu, Qingyuan; Huang, Zhanchang; Yang, Jianlun; Chen, Faxin; Jiang, Shuqing; Ding, Ning; Xu, Rongkun; Xue, Chuang; Zhang, Yang; Sun, Shunkai; Shu, Xiaojian

    2017-09-01

    The radiation transfer in dynamic hohlraums on the PTS facility is preliminarily investigated in this paper. Simulation results show that as the accelerated wire-array plasma impacts onto the foam converter, energy thermalization takes place in a local interaction region near the boundary of the wire-array plasma and the foam converter, and then, high temperature radiation is gradually generated. Its transfer process largely depends on the radiation temperature and the mass density of the converter. When the mass ratio of the wire-array to the converter is near 1.0, the radiation temperature can be increased to about 120 eV with the PTS drive current. In this case, the radiation generated from the interaction region will quickly transfer to the center of the converter. The experimental end-on x-ray images present the overall process of radiation production and transfer of this kind of dynamic hohlraum. As the mass ratio is decreased, the radiation temperature will also be deceased, and the converter will become more opaque to the radiation. In the case of extremely low mass ratios such as lower than 0.3, the peak radiation temperature will be much lower than 100 eV, and the radiation transfers slowly to the interior of the converter and presents large non-uniformity, which is also observed in experiments on the PTS facility.

  18. Measurement of axial radiation properties in Z-pinch dynamic hohlraum at Julong-1

    NASA Astrophysics Data System (ADS)

    Meng, Shijian; Hu, Qingyuan; Ning, Jiaming; Ye, Fan; Huang, Zhanchang; Qin, Yi; Wang, Dong; Xu, Zeping; Xu, Rongkun

    2017-01-01

    Axial radiation properties in Z-pinch dynamic hohlraum is investigated experimentally for the first time at Julong-1 facility in China, employing a load that contains a cylindrical CHO foam placed at the central axis position of the nested tungsten wire array. Time-resolved axially radiating images indicate that the velocity of the radiating shock is 31.9 ± 5.6 cm/μs in shot 0181. At t = -6.5 ns with respect to the peak of radially radiated power at stagnation, the annular width is estimated to be ˜1 mm and the intensities distribution in the shock implies a good azimuthal symmetry of radiation pressure. Axial power is found to peak prior to the arrival of the shock to the axis, which is explained by the balance between shock heating and radiating cooling. Utilizing the end-on radiation images and axial power, the peak radiation temperature in dynamic hohlraum is obtained to be ˜65 eV.

  19. Hohlraum target for overcoming refractive losses in plasma x-ray lasers

    NASA Astrophysics Data System (ADS)

    Masoudnia, Leili; Bleiner, Davide

    2013-05-01

    Refractive losses in laser-produced plasmas used as gain media are caused by electron density gradients, and limit the energy transport range. The pump pulse is thus deflected from the high-gain region and the short wavelength laser signal also steers away, causing loss of collimation. A Hohlraum used as a target makes the plasma homogeneous and can mitigate refractive losses by means of wave-guiding. A computational study combining a hydrodynamics code and an atomic physics code is presented, which includes a ray-tracing modeling based on the eikonal theory of the trajectory equation. This study presents gain calculations based on population inversion produced by free-electron collisions exciting bound electrons into metastable levels in the 3d94d1(J = 0) → 3d94p1(J = 1) transition of Ni-like Sn. Further, the Hohlraum suggests a dramatic enhancement of the conversion efficiency of collisionally excited x-ray lasing for Ni-like Sn.

  20. The hohlraum radiation temperature and M-band fraction on the SGIII-prototype laser facility

    NASA Astrophysics Data System (ADS)

    Huo, Wenyi; Yang, Dong; Lan, Ke; Li, Sanwei; Li, Yongsheng

    2014-10-01

    The hohlraum radiation temperature and M-band fraction are determined by a shock-wave technique and measured by a broadband soft x-ray spectrometer. The peak radiation temperature TR and M-band fraction fm are simultaneously determined by using the observed shock velocities in Al and Ti. For the vacuum Au hohlraum used in the experiments, TR is about 160 eV and fm is between 4.3-6.3% under 1ns laser pulse of 2 k. And TR is about 202 eV and fm is about 9% with laser energy 6 kJ. The Continuous Phase Plate (CPP) for beam smoothing is applied in the experiment, which increases TR to 207 eV while has almost no influence on fm. Comparisons between the results from the two kinds of technologies show that TR from the shock wave technique is lower than that from SXS whether CPP is applied or not. However, fm from the shock wave technique is consistent with that from SXS without CPP, but obviously lower than the SXS's result with CPP.

  1. Study of implosion dynamics of Z-pinch dynamic hohlraum on the Angara-5-1 facility

    NASA Astrophysics Data System (ADS)

    Zhang, Faqiang; Xu, Rongkun; Xu, Zeping; Yang, Jianlun; Li, Zhenghong; Xia, Guangxin; Ning, Jiamin; Li, Linbo; Chen, Dingyang; Chen, Jinchuan

    2015-02-01

    The Z-pinch dynamic hohlraum (ZPDH) is one of high-power X-ray sources that has been used in a variety of high energy-density experiments including inertial confinement fusion (ICF) studies. Dynamic hohlraums driven by a 12-mm and a 18-mm-diameter single tungsten wire arrays embedded with a C16H20O6 foam, respectively, exhibit no visible differences in radiation from the axial exit, although the radial radiation is a little higher in a large array. The analysis of the images suggests that the implosion of a large array is quasi-continuous and has a faster imploding velocity, indicating that the large array is matched to the embedded foam and, oppositely, the small array is mismatched. The analysis also shows that the Rayleigh-Taylor instability develops much harder in implosions of a large array, and this leads to a lower hohlraum temperature. The conclusion was drawn that, for the purpose of enhancing the hohlraum temperature, increasing the conversion efficiency of kinetic energy into thermal energy is more important than increasing the kinetic energy from wire plasma.

  2. Fluorescence imaging as a diagnostic of M-band x-ray drive condition in hohlraum with fluorescent Si targets

    NASA Astrophysics Data System (ADS)

    Li, Qi; Hu, Zhimin; Yao, Li; Huang, Chengwu; Yuan, Zheng; Zhao, Yang; Xiong, Gang; Qing, Bo; Lv, Min; Zhu, Tuo; Deng, Bo; Li, Jin; Wei, Minxi; Zhan, Xiayu; Li, Jun; Yang, Yimeng; Su, Chunxiao; Yang, Guohong; Zhang, Jiyan; Li, Sanwei; Yang, Jiamin; Ding, Yongkun

    2017-01-01

    Fluorescence imaging of surrogate Si-doped CH targets has been used to provide a measurement for drive condition of high-energy x-ray (i.e. M-band x-ray) drive symmetry upon the capsule in hohlraum on Shenguang-II laser facility. A series of experiments dedicated to the study of photo-pumping and fluorescence effect in Si-plasma are presented. To investigate the feasibility of fluorescence imaging in Si-plasma, an silicon plasma in Si-foil target is pre-formed at ground state by the soft x-ray from a half-hohlraum, which is then photo-pumped by the K-shell lines from a spatially distinct laser-produced Si-plasma. The resonant Si photon pump is used to improve the fluorescence signal and cause visible image in the Si-foil. Preliminary fluorescence imaging of Si-ball target is performed in both Si-doped and pure Au hohlraum. The usual capsule at the center of the hohlraum is replaced with a solid Si-doped CH-ball (Si-ball). Since the fluorescence is proportional to the photon pump upon the Si-plasma, high-energy x-ray drive symmetry is equal to the fluorescence distribution of the Si-ball.

  3. pF3D Simulations of Large Outer-Beam Brillouin Scattering from NIF Rugby Hohlraums

    NASA Astrophysics Data System (ADS)

    Langer, Steven; Strozzi, David; Chapman, Thomas; Amendt, Peter

    2015-11-01

    We assess the cause of large outer-beam stimulated Brillouin scattering (SBS) in a NIF shot with a rugby-shaped hohlraum, which has less wall surface loss and thus higher x-ray drive than a cylindrical hohlraum of the same radius. This shot differed from a prior rugby shot with low SBS in three ways: outer beam pointing, split-pointing of the four beams within each outer-beam quadruplet, and a small amount of neon added to the hohlraum helium fill gas. We use pF3D, a massively-parallel, paraxial-envelope laser plasma interaction code, with plasma profiles from the radiation-hydrodynamics code Lasnex. We determine which change between the two shots increased the SBS by adding them one at a time to the simulations. We compare the simulations to experimental data for total SBS power, its spatial distribution at the lens, and the SBS spectrum. For each shot, we use profiles from Lasnex simulations with and without a model for mix at the hohlraum wall-gas interface. Work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. Release number LLNL-ABS-674893.

  4. Usefulness of a Rugby-shaped hohlraum in a Laser M'egaJoule (LMJ) 40-quad configuration

    NASA Astrophysics Data System (ADS)

    Malinie, G.; Vandenboomgaerde, M.; Bastian, J.; Galmiche, D.; Laffite, S.; Liberatore, S.

    2007-11-01

    The LMJ setup will consist of 60 quads in a 3-cone configuration, at angles 33.2^o, 49^o and 59.5^o. First ignition attempts in indirect drive are planned to be made on the way to the completion of the full facility, with only 40 quads in a 2-cone configuration, at angles 33.2^o and 49^o. By analytic considerations, we show that in a 40-quad configuration, the angular location of the hohlraum outer irradiating ring, as seen from the capsule, must be closer to the laser entrance hole than with the full LMJ. The use of a Rugby-shaped hohlraum instead of a cylinder therefore allows to keep a correct symmetry while reducing the wall surface, which improves the global energetic efficiency of the target. Simplified 2D numerical simulations of Rugby hohlraums are presented, achieving a yield of about 30 MJ with our 1.215 mm-radius, CH-uniform-ablator capsule. These results suggests this kind of hohlraum might be an interesting candidate for 40-quad ignition experiments. Work on optimizing the present design and refining the numerical simulations is currently pursued.

  5. Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility.

    PubMed

    Döppner, T; Callahan, D A; Hurricane, O A; Hinkel, D E; Ma, T; Park, H-S; Berzak Hopkins, L F; Casey, D T; Celliers, P; Dewald, E L; Dittrich, T R; Haan, S W; Kritcher, A L; MacPhee, A; Le Pape, S; Pak, A; Patel, P K; Springer, P T; Salmonson, J D; Tommasini, R; Benedetti, L R; Bond, E; Bradley, D K; Caggiano, J; Church, J; Dixit, S; Edgell, D; Edwards, M J; Fittinghoff, D N; Frenje, J; Gatu Johnson, M; Grim, G; Hatarik, R; Havre, M; Herrmann, H; Izumi, N; Khan, S F; Kline, J L; Knauer, J; Kyrala, G A; Landen, O L; Merrill, F E; Moody, J; Moore, A S; Nikroo, A; Ralph, J E; Remington, B A; Robey, H F; Sayre, D; Schneider, M; Streckert, H; Town, R; Turnbull, D; Volegov, P L; Wan, A; Widmann, K; Wilde, C H; Yeamans, C

    2015-07-31

    We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shape closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 10^{16} neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel.

  6. Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility

    DOE PAGES

    Döppner, T.; Callahan, D. A.; Hurricane, O. A.; ...

    2015-07-28

    We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a “highfoot” laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shapemore » closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 1016 neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel.« less

  7. Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility

    SciTech Connect

    Döppner, T.; Callahan, D. A.; Hurricane, O. A.; Hinkel, D. E.; Ma, T.; Park, H. -S.; Berzak Hopkins, L. F.; Casey, D. T.; Celliers, P. P.; Dewald, E. L.; Dittrich, T. R.; Haan, S.; Kritcher, A. L.; MacPhee, A.; Le Pape, S.; Pak, A.; Patel, P. K.; Springer, P. T.; Salmonson, J. D.; Tommasini, R.; Benedetti, L. R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Church, J.; Dixit, S.; Edgell, D.; Edwards, M. J.; Fittinghoff, D. N.; Frenje, J.; Gatu Johnson, M.; Grim, G.; Hatarik, R.; Havre, M.; Herrmann, H.; Izumi, N.; Khan, S. F.; Kline, J. L.; Knauer, J.; Kyrala, G. A.; Landen, O. L.; Merrill, F. E.; Moody, J.; Moore, A. S.; Nikroo, A.; Ralph, J. E.; Remington, B. A.; Robey, H.; Sayre, D.; Schneider, M.; Streckert, H.; Town, R.; Turnbull, D.; Volegov, P. L.; Wan, A.; Widmann, K.; Wilde, C. H.; Yeamans, C.

    2015-07-28

    We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a “highfoot” laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shape closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 1016 neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel.

  8. Planar Wire-Array Z-Pinch Implosion Dynamics and X-Ray Scaling at Multiple-MA Drive Currents for a Compact Multisource Hohlraum Configuration

    SciTech Connect

    Jones, B.; Ampleford, D. J.; Vesey, R. A.; Cuneo, M. E.; Coverdale, C. A.; Waisman, E. M.; Jones, M. C.; Fowler, W. E.; Stygar, W. A.; Serrano, J. D.; Vigil, M. P.; Esaulov, A. A.; Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M.; Chuvatin, A. S.; Rudakov, L. I.

    2010-03-26

    An indirect drive configuration is proposed wherein multiple compact Z-pinch x-ray sources surround a secondary hohlraum. Planar compact wire arrays allow reduced primary hohlraum surface area compared to cylindrical loads. Implosions of planar arrays are studied at up to 15 TW x-ray power on Saturn with radiated yields exceeding the calculated kinetic energy, suggesting other heating paths. X-ray power and yield scaling studied from 1-6 MA motivates viewfactor modeling of four 6-MA planar arrays producing 90 eV radiation temperature in a secondary hohlraum.

  9. Preliminary study on a tetrahedral hohlraum with four half-cylindrical cavities for indirectly driven inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Jing, Longfei; Jiang, Shaoen; Kuang, Longyu; Zhang, Lu; Li, Liling; Lin, Zhiwei; Li, Hang; Zheng, Jianhua; Hu, Feng; Huang, Yunbao; Huang, Tianxuan; Ding, Yongkun

    2017-04-01

    A tetrahedral hohlraum with four half-cylindrical cavities (FHCH) is proposed to balance tradeoffs among the drive symmetry, coupling efficiency, and plasma filling of the hohlraum performance for indirectly driven inertial confinement fusion. The peak drive symmetry in the FHCH with a cavity-to-capsule ratio (CCR) of 2.2 is comparable to those in the spherical hohlraum of CCR  =  4.5 with six laser entrance holes (6LEHs-Sph.) ((Lan et al 2014 Phys. Plasmas 21 010704) and three-axis cylindrical hohlraum (6LEHs-Cyls.) of CCR  =  2.0 (Kuang et al 2016 Sci. Rep. 6 34636), and the filling time of plasma is close to the ones in the 6LEHs-Cyls. and the ignition target Rev5-CH of the national ignition campaign, and about half of that in the 6LEHs-Sph. In particular, the coupling efficiency is about 19% and 16% higher than those of the 6LEHs-Sph. and 6LEHs-Cyls., respectively. Besides, preliminary study indicates that the FHCH has a robust symmetry to uncertainties of power imbalance and pointing errors of laser beams. Furthermore, utilizing the FHCH, the feasibility of a tetrahedral indirect drive approach on the national ignition facility and hybrid indirect-direct drive approach with the laser arrangement designed specially for 6LEHs-Sph. or 6LEHs-Cyls., is also envisioned. Therefore, the proposed hohlraum configuration merits consideration as an alternative route to indirect-drive ignition.

  10. The Physics of Ignition Scale Hohlraums and ICF Implosions: When does size matter?

    NASA Astrophysics Data System (ADS)

    Rosen, Mordecai

    2011-10-01

    Ignition scale, high drive, hohlraums with ICF ignition capsules are four times larger than any laser-illuminated targets attempted previously. In addition, the precision in symmetry and pulse-shape / shock timing required for achieving ignition is quite stringent. This tutorial deals with the challenges presented by these issues. They are now subject to experimental study, facilitated by the capability of the National Ignition Facility (NIF) to deliver, with great precision, the very large laser energy and power needed for ignition. Given this large excursion in scale size, we disentangle here the following: What elements of our previous understanding, based on smaller scale laser experiments, might carry over smoothly to this regime, because they are scale independent? On the other hand, which might need to be refined, because small-scale experimental results were not sufficiently sensitive to issues that may become more important at NIF scale? For example, we explain how hohlraum x-ray drive has an additional component due to the large scale size, allowing Au coronal emission to play a role. Yet at the same time, we explain, on firm theoretical grounds, why certain changes/improvements in hohlraum design, based on previous results on smaller scale lasers, can be made with confidence: Size doesn't always matter. Similarly, we show how large scale-lengths may bring laser-plasma-instabilities (LPI) into more prominence. Equally important, however, is our understanding of how LPI is affected by the basic plasma conditions (Te, ne) . A valuable knowledge base of these basics was obtained via experiments on smaller facilities. A third such example of the interplay between scale dependent and independent phenomena involves the soft-x-ray transport in the CH capsule ablator, in the presence of the higher Z dopants. These dopants are, by design, placed in the ablator in order to control higher frequency x-ray preheat. We present a computational model, (the ``High Flux

  11. Experimental characterization of NIF hohlraum emission in the Rayleigh-Jeans limit (1 eV to 5 eV)

    NASA Astrophysics Data System (ADS)

    Moody, J. D.; Goyon, C. E.; Ross, J. S.; Swadling, G. F.; Moore, A. S.; Baker, K. L.; Thomas, C. A.; Schneider, M. B.; Landen, O. L.; Michel, P. A.; Strozzi, D. J.; Divol, L.; Widmann, K.

    2016-10-01

    We use several measurements to estimate NIF hohlraum emission in the Rayleigh-Jeans limit where hν <hohlraum radiation temperature which is typically 260 to 300 eV. The measurements are primarily optical, consisting of hohlraum emission which transmits through the capsule and is collected by an optical photodiode, optical emission emitted from the laser-entrance hole in the 4 eV range, and various other optical measurements. These measurements can help quantify the laser-plasma interaction processes occurring in the hohlraum and may provide insight into the atomic physics of the Au wall at long wavelength. We describe our findings and discuss interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser

    NASA Astrophysics Data System (ADS)

    Saunders, A. M.; Jenei, A.; Döppner, T.; Falcone, R. W.; Kraus, D.; Kritcher, A.; Landen, O. L.; Nilsen, J.; Swift, D.

    2016-11-01

    X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH2 targets on the OMEGA laser facility at the Laboratory for Laser Energetics in Rochester, NY. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Knowledge gained in this experiment shows a promising future for further XRTS measurements on indirectly driven OMEGA targets.

  13. Development of soft x-ray tracer diagnostics for hohlraum experiments

    SciTech Connect

    MacFarlane, J.J.; Cohen, D.H.; Wang, P.; Peterson, R.R.; Moses, G.A.

    1998-04-01

    The purpose of this report is to summarize work performed by the University of Wisconsin during fiscal year 1996 under the NLUF contract DE-FG-96SF21015. This contract involved the development of soft x-ray spectral diagnostics from tracer layers in hohlraum witness plates. This effort was originally intended to be focused on OMEGA experiments, but the experiments were changed to NOVA because initial indirect drive shots had not yet been performed on the OMEGA upgrade. Data were collected in a series of experiments between January 1997 and October 1997. Experiments were delayed somewhat due to bringing up the Hettrick spectrometer on the NOVA target chamber. The tasks related to the planning, carrying out, and modeling of the experiments are outlined in Table 1.1 and detailed in the remainder of this report.

  14. Convergent ablation measurements of plastic ablators in gas-filled rugby hohlraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Masse, L.; Galmiche, D.

    2015-10-01

    Indirect-drive implosions experiments were conducted on the Omega Laser Facility to test the performance of uniformly doped plastic ablators for Inertial Confinement Fusion. The first convergent ablation measurements in gas-filled rugby hohlraums are reported. Ignition relevant limb velocities in the range from 150 to 300 μm .n s-1 have been reached by varying the laser drive energy and the initial capsule aspect ratio. The measured capsule trajectory and implosion velocity are in good agreement with 2D integrated simulations and a zero-dimensional modeling of the implosions. We demonstrate experimentally the scaling law for the maximum implosion velocity predicted by the improved rocket model [Y. Saillard, Nucl. Fusion 46, 1017 (2006)] in the high-ablation regime case.

  15. Effect of Energetic Electrons Produced by Raman Scattering on Hohlraum Dynamics

    NASA Astrophysics Data System (ADS)

    Strozzi, D. J.; Bailey, D. S.; Doeppner, T.; Divol, L.; Harte, J. A.; Michel, P.; Thomas, C. A.

    2016-10-01

    A reduced model of laser-plasma interactions, namely crossed-beam energy transfer and stimulated Raman scattering (SRS), has recently been implemented in a self-consistent or ``inline'' way in radiation-hydrodynamics codes. We extend this work to treat the energetic electrons produced by Langmuir waves (LWs) from SRS by a suprathermal, multigroup diffusion model. This gives less spatially localized heating than depositing the LW energy into the local electron fluid. We compare the resulting hard x-ray production to imaging data on the National Ignition Facility, which indicate significant emission around the laser entrance hole. We assess the effects of energetic electrons, as well as background electron heat flow, on hohlraum dynamics and capsule implosion symmetry. Work performed under the auspices of the U.S. D.O.E. by LLNL under Contract No. DE-AC52-07NA27344.

  16. Demonstartion of density dependence of x-ray flux in a laser-driven hohlraum

    SciTech Connect

    Young, P E; Rosen, M D; Hammer, J H; Hsing, W S; Glendinning, S G; Turner, R E; Kirkwood, R; Schein, J; Sorce, C; Satcher, J; Hamza, A; Reibold, R A; Hibbard, R; Landen, O; Reighard, A; McAlpin, S; Stevenson, M; Thomas, B

    2008-02-11

    Experiments have been conducted using laser-driven cylindrical hohlraums whose walls are machined from Ta{sub 2}O{sub 5} foams of 100 mg/cc and 4 g/cc densities. Measurements of the radiation temperature demonstrate that the lower density walls produce higher radiation temperatures than the high density walls. This is the first experimental demonstration of the prediction that this would occur [M. D. Rosen and J. H. Hammer, Phys. Rev. E 72, 056403 (2005)]. For high density walls, the radiation front propagates subsonically, and part of the absorbed energy is wasted by the flow kinetic energy. For the lower wall density, the front velocity is supersonic and can devote almost all of the absorbed energy to heating the wall.

  17. General computational spectroscopic framework applied to Z-pinch dynamic hohlraum K-shell argon spectra

    SciTech Connect

    Adams, M L; Sinars, D B; Scott, H A

    2005-01-10

    We describe a general computational spectroscopic framework for interpreting observed spectra. The framework compares synthetic spectra with measured spectra, then optimizes the agreement using the Dakota toolkit to minimize a merit function that incorporates established spectroscopic techniques. We generate synthetic spectra using the self-consistent nonlocal thermodynamic equilibrium atomic kinetics and radiative transfer code Cretin, relativistic atomic structure and cross section data from Hullac, and detailed spectral line shapes from Totalb. We test the capabilities of both our synthetic spectra model and general spectroscopic framework by analyzing a K-shell argon spectrum from a Z-pinch dynamic hohlraum inertial confinement fusion capsule implosion experiment. The framework obtains close agreement between an experimental spectrum measured by a time integrated focusing spectrometer and the optimal synthetic spectrum. The synthetic spectra show that considering the spatial extent of the capsule and including the effects of optically thick resonance lines significantly affects the interpretation of measured spectra.

  18. Design and experimental study of a secondary hohlraum radiation source with laser focal spots blocked

    SciTech Connect

    Song, Tianming Zhu, Tuo; Yang, Jiamin; Huang, Chengwu; Wang, Feng; Peng, Xiaoshi; Xu, Tao; Li, Zhichao; Zhang, Huan

    2016-01-15

    A design of secondary hohlraum radiation source with laser focal spots blocked is introduced. The hard x-ray radiation such as the gold M-band emission and hot electrons from the coronal plasma were designed to be shielded using a cylindrical shield. Three-dimensional view factor analysis was carried out to optimize the shield structure to achieve higher radiation temperature. An experiment was performed at Shenguang III prototype laser facility to verify the design. Velocity Interferometer System for Any Reflector was used to measure the shock wave speed in a three-stepped Al sample driven by this radiation source and the peak radiation temperature of the radiation source was estimated to be about 90 eV.

  19. X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser.

    PubMed

    Saunders, A M; Jenei, A; Döppner, T; Falcone, R W; Kraus, D; Kritcher, A; Landen, O L; Nilsen, J; Swift, D

    2016-11-01

    X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH2 targets on the OMEGA laser facility at the Laboratory for Laser Energetics in Rochester, NY. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Knowledge gained in this experiment shows a promising future for further XRTS measurements on indirectly driven OMEGA targets.

  20. Radial electric field 3D modeling for wire arrays driving dynamic hohlraums on Z.

    SciTech Connect

    Mock, Raymond Cecil

    2007-06-01

    The anode-cathode structure of the Z-machine wire array results in a higher negative radial electric field (Er) on the wires near the cathode relative to the anode. The magnitude of this field has been shown to anti-correlate with the axial radiation top/bottom symmetry in the DH (Dynamic Hohlraum). Using 3D modeling, the structure of this field is revealed for different wire-array configurations and for progressive mechanical alterations, providing insight for minimizing the negative Er on the wire array in the anode-to-cathode region of the DH. Also, the 3D model is compared to Sasorov's approximation, which describes Er at the surface of the wire in terms of wire-array parameters.

  1. Imposed magnetic field and hot electron propagation in inertial fusion hohlraums

    SciTech Connect

    Strozzi, David J.; Perkins, L. J.; Marinak, M. M.; Larson, D. J.; Koning, J. M.; Logan, B. G.

    2015-12-02

    The effects of an imposed, axial magnetic field $B_{z0}$ on hydrodynamics and energetic electrons in inertial confinement fusion indirect-drive hohlraums are studied. We present simulations from the radiation-hydrodynamics code HYDRA of a low-adiabat ignition design for the National Ignition Facility, with and without $B_{z0}=70~\\text{T}$. The field’s main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or ‘hot’, electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium–tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA as well as sources based on inner-beam stimulated Raman scattering. Furthermore, the effect of the field on deuterium–tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.

  2. Imposed magnetic field and hot electron propagation in inertial fusion hohlraums

    DOE PAGES

    Strozzi, David J.; Perkins, L. J.; Marinak, M. M.; ...

    2015-12-02

    The effects of an imposed, axial magnetic fieldmore » $$B_{z0}$$ on hydrodynamics and energetic electrons in inertial confinement fusion indirect-drive hohlraums are studied. We present simulations from the radiation-hydrodynamics code HYDRA of a low-adiabat ignition design for the National Ignition Facility, with and without $$B_{z0}=70~\\text{T}$$. The field’s main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or ‘hot’, electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium–tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA as well as sources based on inner-beam stimulated Raman scattering. Furthermore, the effect of the field on deuterium–tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.« less

  3. Titanium lined hohlraums as multi-keV x-ray converters

    NASA Astrophysics Data System (ADS)

    Girard, Frederic; Primout, Michel; Naudy, Michel; Jadaud, Jean-Paul; Villette, Bruno; Fournier, Kevin B.

    2006-10-01

    Developments of bright multi-keV K-shell emission sources [1-3] are necessary for ICF studies such as radiography of dense materials. Our recent works with prepulsed foils of titanium (Heα at 4.7 keV), copper (Heα at 8.3 keV) and germanium (Heα at 10.3 keV) showed high multi-keV x-ray conversion efficiencies up to 8.0%, 1.0% and 2.5% (respectively) [1,2]. In comparison with thick foils, the preexploded foils conversion efficiencies are increased by a factor of more than 2. Hohlraums with a titanium liner have been used on the OMEGA laser facility in Rochester to quantify the multi-keV x-ray conversion. For the first time, a laser pulse with a picket prior to the main bulk of laser power has been employed with a Ti-lined hohlraum. X-ray produced with this laser pulse with picket is compared to the case with a square 1 ns pulse shape. X-ray power was measured by the broadband spectrometer DMX (filtered diodes) and the absolutely calibrated crystal spectrometer HENWAY. Multi-keV emission is diagnosed by a full set of diagnostics giving conversion efficiencies, time dependant x-ray power and imaging, time integrated imaging and high resolution spectra of titanium. [1] F. Girard et al., Phys. Plasmas, 12, 092705 (2005) [2] D. Babonneau et al., submitted in Phys. Rev. Lett. [3] K. B. Fournier et al., Phys. Rev. Lett., 92, 165005 (2004)

  4. The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility

    SciTech Connect

    Schneider, M. B. MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Dewald, E. L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Hinkel, D. E.; Hsing, W. W.; Kervin, M. L.; Landen, O. L.; Lindl, J. D.; May, M. J.; and others

    2015-12-15

    At the National Ignition Facility, a thermal X-ray drive is created by laser energy from 192 beams heating the inside walls of a gold cylinder called a “hohlraum.” The x-ray drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH radius decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma from the high-intensity region in the center of the LEH pushing radially outward. The x-ray drive on the capsule is deduced by measuring the time evolution and spectra of the x-radiation coming out of the LEH and correcting for geometry and for the radius of the LEH. Previously, the LEH radius was measured using time-integrated images in an x-ray band of 3–5 keV (outside the thermal x-ray region). For gas-filled hohlraums, the measurements showed that the LEH radius is larger than that predicted by the standard High Flux radiation-hydrodynamic model by about 10%. A new platform using a truncated hohlraum (“ViewFactor hohlraum”) is described, which allows time-resolved measurements of the LEH radius at thermal x-ray energies from two views, from outside the hohlraum and from inside the hohlraum. These measurements show that the LEH radius closes during the low power part of the pulse but opens up again at peak power. The LEH radius at peak power is larger than that predicted by the models by about 15%–20% and does not change very much with time. In addition, time-resolved images in a >4 keV (non-thermal) x-ray band show a ring of hot, optically thin gold plasma just inside the optically thick LEH plasma. The structure of this plasma varies with time and with Cross Beam Energy Transfer.

  5. Performance of beryllium targets with full-scale capsules in low-fill 6.72-mm hohlraums on the National Ignition Facility

    DOE PAGES

    Simakov, A. N.; Wilson, D. C.; Yi, S. A.; ...

    2017-05-10

    When used with 1.06-mm beryllium (Be) capsules on the National Ignition Facility, gold hohlraums with the inner diameter of 5.75 mm and helium gas fill density of 1.6 mg/cm3 exhibit significant drive degradation due to laser energy backscatter (of order 14%–17%) and “missing” X-ray drive energy (about 32% during the main pulse). Also, hard to simulate cross-beam energy transfer (CBET) must be used to control the implosion symmetry. Larger, 6.72-mm hohlraums with fill densities ≤0.6 mg/cm3 generally offer improved drive efficiency, reduced hot-electron preheat, and better control of the implosion symmetry without CBET. Recently, we carried out an exploratory campaignmore » to evaluate performance of 1.06-mm Be capsules in such hohlraums and determine optimal hohlraum parameters. Specifically, we performed in this paper a hohlraum fill-density scan with a three-shock, 9.5-ns laser pulse and found that an appropriate axial laser repointing and azimuthal outer-quad splitting resulted in significantly improved hohlraum energetics at fill densities ≤0.3 mg/cm3 (with backscattered and “missing” energies being of about 5% and 23% of the total laser energy, respectively). The capsule shape at stagnation was slightly oblate and improved with lowering the fill density. We also performed an implosion with a lower-picket, 12.6-ns pulse at the hohlraum fill density of 0.15 mg/cm3 to observe comparable hohlraum energetics (about 3% of backscattered and 27% of “missing” energy) but an even more oblate implosion shape. Finally, achieving symmetric implosions of 1.06-mm Be capsules in low-fill, 6.72-mm gold hohlraums with reasonably low-adiabat pulses may not be feasible. However, symmetric implosions have recently been successfully demonstrated in such hohlraums with 0.8-mm Be capsules.« less

  6. Direct measurement of x-ray flux for a pre-specified highly-resolved region in hohlraum.

    PubMed

    Ren, Kuan; Liu, Shenye; Hou, Lifei; Du, Huabing; Ren, Guoli; Huo, Wenyi; Jing, Longfei; Zhao, Yang; Yang, Zhiwen; Wei, Minxi; Deng, Keli; Yao, Li; Li, Zhichao; Yang, Dong; Zhang, Chen; Yan, Ji; Yang, Guohong; Li, Sanwei; Jiang, Shaoen; Ding, Yongkun; Liu, Jie; Lan, Ke

    2015-09-21

    A space-resolving flux detector (SRFD) is developed to measure the X-ray flux emitted from a specified region in hohlraum with a high resolution up to 0.11mm for the first time. This novel detector has been used successfully to measure the distinct X-ray fluxes emitted from hot laser spot and cooler re-emitting region simultaneously, in the hohlraum experiments on SGIII prototype laser facility. According to our experiments, the ratio of laser spot flux to re-emitted flux shows a strong time-dependent behavior, and the area-weighted flux post-processed from the measured laser spot flux and re-emitting wall flux agrees with that measured from Laser Entrance Hole by using flat-response X-ray detector (F-XRD). The experimental observations is reestablished by our two-dimensional hydrodynamic simulations and is well understood with the power balance relationship.

  7. Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li + ion beam-driven hohlraums

    NASA Astrophysics Data System (ADS)

    Fehl, D. L.; Chandler, G. A.; Biggs, F.; Dukart, R. J.; Moats, A. R.; Leeper, R. J.

    1997-01-01

    X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li+ ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively in obtaining time-resolved x-ray spectra and radiation temperatures from this diagnostic. The UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies (⩽100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time-history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum.

  8. 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.

  9. Three-dimensional simulations of the angular and polarization dependence of stimulated Brillouin backscattering from NIF hohlraums

    NASA Astrophysics Data System (ADS)

    Berger, Richard; Langdon, A. B.; Thomas, C. A.; Baker, K. L.; Goyon, C. S.; Turnbull, D. P.

    2016-10-01

    The National Ignition Facility (NIF) groups its 192 beams in 48 quads, 2/3 of which are `outer' beams and 1/3 `inner' beams. Half of the outer quads are focused at the laser entrance hole (LEH) at an mean angle of 44° and the other half at 50° with respect to the hohlraum axis. The majority of the stimulated Brillouin scatter (SBS) is reflected into the 50° quads, and most of that into the 52° beams. That observation we reproduce with our simulations that use the wave propagation code, pF3D. Simulations considered a number of different pulse shapes, wall materials, capsule materials, and initial fill gas density with the plasma properties taken from 2D cylindrically-symmetric, radiation-hydrodynamic simulations of the hohlraum, capsule included. The simulations predict that different hohlraum designs have different fractions, between 20% and 50%, of the total SBS reflected into the backscattered light collection optics (the so-called FABS). The amount of light backscattered outside of FABS is not currently measured but is assumed to be 70% of the light backscattered. That assumption is a reasonable but not accurate estimate. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. NIF-scale re-emission sphere measurements of early-time Tr = 100 eV hohlraum symmetry (invited).

    PubMed

    Dewald, E L; Thomas, C; Milovich, J; Edwards, J; Sorce, C; Kirkwood, R; Meeker, D; Jones, O; Izumi, N; Landen, O L

    2008-10-01

    The indirect-drive National Ignition Campaign (NIC) proposes to set the first 2 ns of hohlraum radiation symmetry by observing the instantaneous soft x-ray re-emission pattern from a high-Z sphere in place of the ignition capsule. To assess this technique under NIC conditions, we used the Omega Laser Facility to image the re-emission of Bi coated spheres with 200 ps temporal, 50-100 microm spatial, and 30% spectral resolution. The sphere is driven by 70% NIC-scale vacuum Au hohlraums heated to Tr=100 eV using two cones per side laser beam illumination. The experiments have demonstrated the required accuracies of <3%P(2)/P(0) and <3%P(4)/P(0) Legendre mode flux asymmetry at both 900 and 1200 eV re-emission photon energies. The re-emission patterns at 900 and 1200 eV are also consistent with each other and their relative dependence on radiation temperature. We measured the P(2)/P(0) and P(4)/P(0) dependence to laser cone power ratio. View factor calculations are in agreement with the experimentally measured radiation flux and re-emit images when assuming 55% inner beam and 100 % outer beam coupling into x rays at the hohlraum wall.

  11. 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.

  12. The first measurements of soft x-ray flux from ignition scale Hohlraums at the National Ignition Facility using DANTE (invited).

    PubMed

    Kline, J L; Widmann, K; Warrick, A; Olson, R E; Thomas, C A; Moore, A S; Suter, L J; Landen, O; Callahan, D; Azevedo, S; Liebman, J; Glenzer, S H; Conder, A; Dixit, S N; Torres, P; Tran, V; Dewald, E L; Kamperschroer, J; Atherton, L J; Beeler, R; Berzins, L; Celeste, J; Haynam, C; Hsing, W; Larson, D; MacGowan, B J; Hinkel, D; Kalantar, D; Kauffman, R; Kilkenny, J; Meezan, N; Rosen, M D; Schneider, M; Williams, E A; Vernon, S; Wallace, R J; Van Wonterghem, B; Young, B K

    2010-10-01

    The first 96 and 192 beam vacuum Hohlraum target experiments have been fielded at the National Ignition Facility demonstrating radiation temperatures up to 340 eV and fluxes of 20 TW/sr as viewed by DANTE representing an ∼20 times flux increase over NOVA/Omega scale Hohlraums. The vacuum Hohlraums were irradiated with 2 ns square laser pulses with energies between 150 and 635 kJ. They produced nearly Planckian spectra with about 30±10% more flux than predicted by the preshot radiation hydrodynamic simulations. To validate these results, careful verification of all component calibrations, cable deconvolution, and software analysis routines has been conducted. In addition, a half Hohlraum experiment was conducted using a single 2 ns long axial quad with an irradiance of ∼2×10(15) W/cm(2) for comparison with NIF Early Light experiments completed in 2004. We have also completed a conversion efficiency test using a 128-beam nearly uniformly illuminated gold sphere with intensities kept low (at 1×10(14) W/cm(2) over 5 ns) to avoid sensitivity to modeling uncertainties for nonlocal heat conduction and nonlinear absorption mechanisms, to compare with similar intensity, 3 ns OMEGA sphere results. The 2004 and 2009 NIF half-Hohlraums agreed to 10% in flux, but more importantly, the 2006 OMEGA Au Sphere, the 2009 NIF Au sphere, and the calculated Au conversion efficiency agree to ±5% in flux, which is estimated to be the absolute calibration accuracy of the DANTEs. Hence we conclude that the 30±10% higher than expected radiation fluxes from the 96 and 192 beam vacuum Hohlraums are attributable to differences in physics of the larger Hohlraums.

  13. Z-Pinch Generated X-Rays in Static-Wall Hohlraum Geometry Demonstrate Potential for Indirect-Drive ICF Studies

    SciTech Connect

    BOWERS,RICHARD; CHANDLER,GORDON A.; HEBRON,DAVID E.; LEEPER,RAMON J.; MATUSLKA,WALTER; MOCK,RAYMOND CECIL; NASH,THOMAS J.; OLSON,CRAIG L.; PETERSON,BOB; PETERSON,DARRELL; RUGGLES,LAURENCE E.; SANFORD,THOMAS W. L.; SIMPSON,WALTER W.; STRUVE,KENNETH W.; VESEY,ROGER A.

    1999-11-01

    Hohlraums of full ignition scale (6-mm diameter by 7-mm length) have been heated by x-rays from a z-pinch magnet on Z to a variety of temperatures and pulse shapes which can be used to simulate the early phases of the National Ignition Facility (NIF) temperature drive. The pulse shape is varied by changing the on-axis target of the z pinch in a static-wall-hohlraum geometry. A 2-{micro}m-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm{sup 3} CH, for example, produces foot-pulse conditions of {approx}85 eV for a duration of {approx}10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm{sup 3} CH generates first-step-pulse conditions of {approx}122 eV for a duration of a few ns. Alternatively, reducing the hohlraum size (to 4-mm diameter by 4-mm length) with the latter target has increased the peak temperature to {approx}150 eV, which is characteristic of a second-step-pulse temperature. In general, the temperature T of these x-ray driven hohlraums is in agreement with the Planckian relation T{approx}(P/A){sup 1/4}. P is the measured x-ray input power and A is the surface area of the hohlraum. Fully-integrated 2-D radiation-hydrodynamic simulations of the z pinch and subsequent hohlraum heating show plasma densities within the useful volume of the hohlraums to be on the order of air or less.

  14. Z-Pinch Generated X-Rays in Static-Wall Hohlraum Geometry Demonstrate Potential for Indirect-Drive ICF Studies

    SciTech Connect

    Sandord, T.W.L.; Olson, R.E.; Chandler, G.A.; Hebron, D.E.; Mock, R.C.; Leeper, R.J.; Nash, T.J.; Ruggles, L.E.; Simpson, W.W.; Struve, K.W.; Vesey, R.A.; Bowers, R.L.; Matuska, W.; Peterson, D.L.; Peterson, R.R.

    1999-08-25

    Hohlraums of full ignition scale (6-mm diameter by 7-mm length) have been heated by x-rays from a z-pinch target on Z to a variety of temperatures and pulse shapes which can be used to simulate the early phases of the National Ignition Facility (NIF) temperature drive. The pulse shape is varied by changing the on-axis target of the z pinch in a static-wall-hohlraum geometry. A 2-{micro}m-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm{sup 3} CH, for example, produces foot-pulse conditions of {minus}85 eV for a duration of {approximately} 10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm{sup 3} CH generates first-step-pulse conditions of {approximately} 122 eV for a duration of a few ns. Alternatively, reducing the hohlraum size (to 4-mm diameter by 4-mm length) with the latter target has increased the peak temperature to {approximately} 150 eV, which is characteristic of a second-step-pulse temperature. In general, the temperature T of these x-ray driven hohlraums is in agreement with the Planckian relation (T-(P/A){sup 1/4}). P is the measured x-ray input power and A is the surface area of the hohlraum. Fully-integrated 2-D radiation-hydrodynamic simulations of the z pinch and subsequent hohlraum heating show plasma densities within the useful volume of the hohlraums to be on the order of air or less.

  15. New two-dimensional space-resolving flux detection technique for measurement of hohlraum inner radiation in Shenguang-III prototype

    SciTech Connect

    Ren, Kuan; Liu, Shenye Du, Huabing; Hou, Lifei; Jing, Longfei; Zhao, Yang; Yang, Zhiwen; Wei, Minxi; Deng, Keli; Yao, Li; Yang, Guohong; Li, Sanwei; Ding, Yongkun; Lan, Ke; Liu, Jie; Zhu, Xiaoli; Yi, Lin

    2015-10-15

    The space-resolving measurement of X-ray flux from a specific area (laser spot, re-emitting wall, or capsule) inside the hohlraum is an ongoing and critical problem in indirectly driven inertial-confinement fusion experiments. In this work, we developed a new two-dimensional space-resolving flux detection technique to measure the X-ray flux from specific areas inside the hohlraum by using the time- and space-resolving flux detector (SRFD). In two typical hohlraum experiments conducted at the Shenguang-III prototype laser facility, the X-ray flux and radiation temperature from an area 0.2 mm in diameter inside the hohlraum were measured through the laser entrance hole (LEH). The different flux intensities and radiation temperatures detected using the SRFD from the inner area of the LEH were compared with the result measured using the flat-response X-ray detector from the entire LEH. This comparison was also analyzed theoretically. The inner area detected using the SRFD was found to be the re-emitting wall area alone. This important improvement in space-resolving X-ray flux measurement will enhance the current X-ray flux space characterization techniques, thereby furthering the quantitative understanding of X-ray flux space behavior in the hohlraum.

  16. New two-dimensional space-resolving flux detection technique for measurement of hohlraum inner radiation in Shenguang-III prototype.

    PubMed

    Ren, Kuan; Liu, Shenye; Du, Huabing; Hou, Lifei; Jing, Longfei; Zhao, Yang; Yang, Zhiwen; Wei, Minxi; Deng, Keli; Yao, Li; Yang, Guohong; Li, Sanwei; Lan, Ke; Liu, Jie; Zhu, Xiaoli; Ding, Yongkun; Yi, Lin

    2015-10-01

    The space-resolving measurement of X-ray flux from a specific area (laser spot, re-emitting wall, or capsule) inside the hohlraum is an ongoing and critical problem in indirectly driven inertial-confinement fusion experiments. In this work, we developed a new two-dimensional space-resolving flux detection technique to measure the X-ray flux from specific areas inside the hohlraum by using the time- and space-resolving flux detector (SRFD). In two typical hohlraum experiments conducted at the Shenguang-III prototype laser facility, the X-ray flux and radiation temperature from an area 0.2 mm in diameter inside the hohlraum were measured through the laser entrance hole (LEH). The different flux intensities and radiation temperatures detected using the SRFD from the inner area of the LEH were compared with the result measured using the flat-response X-ray detector from the entire LEH. This comparison was also analyzed theoretically. The inner area detected using the SRFD was found to be the re-emitting wall area alone. This important improvement in space-resolving X-ray flux measurement will enhance the current X-ray flux space characterization techniques, thereby furthering the quantitative understanding of X-ray flux space behavior in the hohlraum.

  17. Imposed magnetic field and hot electron propagation in inertial fusion hohlraums

    NASA Astrophysics Data System (ADS)

    Strozzi, David J.; Perkins, L. J.; Marinak, M. M.; Larson, D. J.; Koning, J. M.; Logan, B. G.

    2015-12-01

    > . The field's main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or `hot', electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium-tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA as well as sources based on inner-beam stimulated Raman scattering. The effect of the field on deuterium-tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.

  18. High Resolution Integrated Hohlraum-Capsule Simulations for Virtual NIF Ignition Campaign

    NASA Astrophysics Data System (ADS)

    Jones, O. S.; Marinak, M. M.; Cerjan, C. J.; Clark, D. S.; Edwards, M. J.; Haan, S. W.; Langer, S. H.; Salmonson, J. D.

    2009-11-01

    We have undertaken a virtual campaign to assess the viability of the sequence of NIF experiments planned for 2010 that will experimentally tune the shock timing, symmetry, and ablator thickness of a cryogenic ignition capsule prior to the first ignition attempt. The virtual campaign consists of two teams. The ``red team'' creates realistic simulated diagnostic data for a given experiment from the output of a detailed radiation hydrodynamics calculation that has physics models that have been altered in a way that is consistent with probable physics uncertainties. The ``blue team'' executes a series of virtual experiments and interprets the simulated diagnostic data from those virtual experiments. To support this effort we have developed a capability to do very high spatial resolution integrated hohlraum-capsule simulations using the Hydra code. Surface perturbations for all ablator layer surfaces and the DT ice layer are calculated explicitly through mode 30. The effects of the fill tube, cracks in the ice layer, and defects in the ablator are included in models extracted from higher resolution calculations. Very high wave number mix is included through a mix model. We will show results from these calculations in the context of the ongoing virtual campaign.

  19. Experimental investigation of Eagle nebula pillars using a multiple hohlraum array

    NASA Astrophysics Data System (ADS)

    Martinez, David; Kane, Jave; Villette, Bruno; Pound, Mark; Casner, Alexis; Heeter, Robert; Mancini, Roberto

    2014-10-01

    The ``pillars of creation'' are stunningly beautiful and physically puzzling molecular cloud structure in the Eagle nebula. Formation of these pillars has been subject of debate since their observation. Although extensive observation and modeling have attempted to answer the creation of the observed pillars, experiments have not adequately tested the theoretical models surrounding the photoevaporation of the molecular clouds. Recent Omega EP experiments at the LLE developed a 30 ns x-ray drive using a multiple hohlraum array (``Gatling gun'' approach) to drive the photoevaporation process and test pillar formation. This proof of principle experiment imaged the initial stages of a pillar using Ti area backlighter through a driven 50 mg/cc R/F foam with an embedded solid density CH ball. This presentation will give an overview of the experimental design and results from the experiment. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-656872.

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

    DOE PAGES

    Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; ...

    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

  1. 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.

  2. Self-generated magnetic fields and electron transport in laser driven hohlraums

    NASA Astrophysics Data System (ADS)

    Edwards, John; Alley, Ed; Hammer, Jim; Town, Richard; Haines, Malcolm

    2002-11-01

    It is well known that magnetic fields can be generated during the interaction of an intense laser beam with solid targets. The principle source of magnetic field from Ohm's law is the familiar grad(T)xgrad(n) term, which results in Megagauss fields for laser intensities typical of inertial fusion and other high energy density experiments. In a hohlraum the main consequence of this is to increase the electron temperature by x2 near the laser entrance holes because of reduced thermal conduction in the cross-field (axial) direction. Despite the "localizing" effect of the magnetic field on the electrons, it appears that the diffusion approximation for electron heat flow breaks down, with the departure becoming progressively worse as the laser power is increased. The results of Lasnex simulations are used to illustrate these effects for laser powers ranging from 10TW to 500TW which cover conditions from Nova to NIF. Potential knock on consequences for inertial fusion are discussed. -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.

  3. Integrated P1 Hohlraum/Capsule Simulations with Comparison to Neutron and X-Ray Measurements

    NASA Astrophysics Data System (ADS)

    Eder, D. C.; Spears, B. K.; Town, R. P.; Jones, O. S.; Munro, D. H.; Peterson, J. L.; Ma, T.; Pak, A. K.; Benedetti, L. R.; Hatchett, S. P.; Knauer, J. P.; MacKinnon, A. J.; Yeamans, C. B.; McNaney, J. M.; Casey, D. T.; NIF Team

    2013-10-01

    We discuss integrated hohlraum/capsule simulations that drive a DT symcap capsule downward in a NIF experiment by increasing/decreasing the peak power in the upper/lower laser beams by 8%. This laser asymmetry results in a radiation drive P1/P0 at the capsule ablation surface of 2% and a downward capsule velocity of 125 microns/ns. The simulation shows small (<1%) changes in the P2 and P4 moments of the x-ray self-emission as compared to a simulation with no laser asymmetry. The calculated reduction in yield due to the induced P1 is 20%. Simulations for DT layered capsules for comparable velocities have yields an order of magnitude lower than simulations with stationary capsules. The velocity is measured by comparing the arrival times of DD and DT neutrons at detectors located at different locations. Preliminary data from a recent shot gives a downward velocity of order 100 microns/ns consistent with simulations. We also compare pre- and post-shot simulations with x-ray images at different energies. The ability to correct for capsule velocity, e.g., due to different upper/lower crossbeam transfer energies, is another tool in the quest for ignition. This work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-640047.

  4. Simulations of the 3-Shock HDC gas-filled hohlraum experiments at the NIF

    NASA Astrophysics Data System (ADS)

    Milovich, Jose; Ross, J. S.; Ho, D.; Weber, C.; Sepke, S.; Khan, S.; Cerjan, C.; Meezan, N.; MacKinnon, A.

    2015-11-01

    We describe simulation efforts to design and field a series of high-density-carbon (HDC) capsule tuning experiments in 1.6 mg/cc gas-filled hohlraums at the National Ignition Facility (NIF), culminating in two DT-layered shots. The radiation-hydrodynamics code HYDRA coupled to an off-line power transfer model was employed to ascertain the optimal laser pulse that minimizes radiation asymmetries and implosion adiabat for a given stability margin. We found that these HDC targets have similar sensitivity as their CH ``high-foot'' counterparts when laser cone-fraction and power as well as ablator thickness are varied, leading to comparable implosions. A point of divergence, however, is the measured neutron down-scatter-ratio (DSR) that typically gauges the degree of compression obtained in a DT implosion, with HDC targets having approximately half the CH value. Concerted efforts are underway to understand and ascertain the causes of this discrepancy. Simulations and comparisons with data will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  5. Cryogenic THD and DT 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.; Khan, S. F.; Pak, A. E.; Divol, L.; Ho, D. D.; Ma, T.; Doeppner, T.; Rygg, J. R.; Field, J. E.; Jones, O. S.; Milovich, J. L.; Kozioziemski, B. J.; Hamza, A. V.; MacKinnon, A. J.; Hsing, W. W.; Edwards, M. J.

    2014-10-01

    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 <10 ns. A series of experiments in 2013 on the National Ignition Facility culminated in a DT layered implosion driven by a 6.5 ns, 2-shock laser pulse. This talk describes these experiments and comparisons with the design code HYDRA. Backlit radiography of a THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape; however, other diagnostics suggested an asymmetric compressed fuel layer. The streak camera-based SPIDER diagnostic showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of a low-temperature hot spot. Changes to the laser pulse-shape and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot-spot and a thermonuclear yield of 1 . 8 ×1015 neutrons. Prepared by LLNL under Contract DE-AC52-07NA27344.

  6. X-ray Power and Energy output of Z-Machine Dynamic Hohlraums

    NASA Astrophysics Data System (ADS)

    Idzorek, G.; Tierney, T.; Watt, R.

    2006-10-01

    Los Alamos performs radiation flow experiments at the Z-machine in order to verify their modelling codes. Critical input to these codes is the actual radiation power profile which flows into the experiment. Our standard diagnostic suite consists of X-ray Diodes (XRD), silicon photodiodes, and nickel thin film bolometers. Custom written computer software examines the raw data to determine the data quality, folds in detector spectral response, calculates a multi-detector spectral unfold, and yields an equivalent Planckian temperature profile. Sets of diagnostics view the dynamic hohlraum from the side, top axial anode side, and bottom axial cathode side. Results to date yield some interesting conclusions: Correlation between the various diagnostic views seems tenuous at best. Identical nickel foil bolometers usually agree within 10%. At low bolometer-foil temperature increases the bolometers agree with integrated XRD power unfolds but diverge at higher temperature increases. For identically filtered X-ray diodes the integrated response of photocathodes may vary an factor of two. XRD's usually unfold to yield a Planckian-like spectrum. Top axial measurements consistently yield higher temperatures than bottom axial diagnostics. In our presentation we will compare the diagnostic techniques, analysis, and results to establish drive conditions for our experiments.

  7. Assessing the two plasmon decay instability in ignition-scale hohlraums

    SciTech Connect

    Kruer, W L; Meezan, N; Town, R; Strozzi, D; Wilks, S; Williams, E; Meeker, D; Suter, L; Regan, S

    2009-10-08

    In recent experiments Sean Regan, et. al. for the first time observed the 2{omega}{sub pe} instability from window plasma in hohlraum targets. This instability can also operate at peak power near the edge of the inner beams in the ablator plasma and near the edge of the outer beams in the liner plasma. Fortunately, only a small fraction of the laser energy was estimated to be at risk. A more quantitative assessment of the energy at risk at peak power and its sensitivity to variations in target design and to details of the instability threshold model will here be given. They also explore how strong collisionality restricts this instability in the Au wall plasma. They show that the instability threshold can be significantly reduced for laser beams with an angle of incidence of about 60 degrees due to the swelling of the laser field near its turning point. A simple model is given. It is also shown that for frequently cited plasma conditions, the SRS-scattered light wave can itself drive the 2{omega}{sub pe} instability. This effect is relevant for the nonlinear saturation of SRS and the resulting heated electron generation. Some estimates are given. Finally, several important issues concerning the high-energy electron distributions due to the 2{omega}{sub pe} instability and other laser plasma processes are discussed.

  8. Effects of self-generated magnetic fields on hohlraum simulation at NIF

    NASA Astrophysics Data System (ADS)

    Farmer, W. A.; Strozzi, D. J.; Hinkel, D. E.; Rosen, M. D.; Jones, O. S.; Koning, J. M.; Marinak, M. M.

    2016-10-01

    Non-parallel density and pressure gradients that develop during matter ablation on a laser irradiated target lead to self-generated magnetic fields through the well-known Biermann-battery effect. For laser intensities present during ICF relevant scenarios on NIF, megagauss fields can develop. The presence of large magnetic fields leads to a non-negligible Hall parameter, defined as the product of the electron cyclotron frequency and the electrion-ion collision time. When the Hall parameter is of order unity or greater, a significant reduction in the cross-field heat flux occurs. Large magnetic fields are limited by the inclusion of the Nernst term, which advects the magnetic fields in the direction of the heat flux (or from the ablation front into the denser wall). This advection combined with resistive diffusion of the magnetic field limits the strength of the self-generated field within the hohlraum. We report changes in simulation results obtained when using the MHD package in the radiation-hydrodynamics code, HYDRA, which models the evolutions of the magnetic fields. This work was supported by the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Using hard-X-ray images of ignition hohlraums on NIF to characterize hot electrons generated by laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Divol, Laurent; Doeppner, T.; Thomas, C.; Dewald, E.; Park, H.; Schneider, M.; Lacaille, G.; Michel, P.; Town, R.; Meezan, N.; Moody, J.; Kline, J.; Glenzer, S.; Landen, O.

    2011-10-01

    Using multi-channel hard X-ray images of an ignition hohlraum taken along two axis and the time-integrated FFLEX broadband spectrometer that measures Bremsstrahlung hard X-rays emitted in the hohlraum wall by energetic electrons, we characterize the location of hot electron generation. We distinguish two hot electron components of the spectrum: a 20 keV thermal-like component related to Stimulated Raman scattering and a ``super ho'' (>60 keV) component due to LPI at higher density. In addition, the effect of the hohlraum thermal emission (with Thot ~ 2-4 keV) on this analysis will be assessed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. Direct Measurements of an increased threshold for stimulated Brillouin scattering with polarization smoothing in ignition hohlraum plasmas

    SciTech Connect

    Froula, D; Divol, L; Berger, R L; London, R; Meezan, N; Neumayer, P; Ross, J S; Stagnito, S; Suter, L; Glenzer, S H; Strozzi, D

    2007-11-08

    We demonstrate a significant reduction of stimulated Brillouin scattering by polarization smoothing. The intensity threshold is measured to increase by a factor of 1.7 {+-} 0.2 when polarization smoothing is applied. The results were obtained in a high-temperature (T{sub 3} {approx_equal} 3 keV) hohlraum plasma where filamentation is negligible in determining the backscatter threshold. These results are explained by an analytical model relevant to ICF plasma conditions that modifies the linear gain exponent to account for polarization smoothing.

  11. Indirect drive ablative Rayleigh-Taylor experiments with rugby hohlraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Galmiche, D.; Huser, G.; Jadaud, J.-P.; Liberatore, S.; Vandenboomgaerde, M.

    2009-09-01

    Results of ablative Rayleigh-Taylor instability growth experiments performed in indirect drive on the OMEGA laser facility [T. R. Boehly, D. L. Brown, S. Craxton et al., Opt. Commun. 133, 495 (1997)] are reported. These experiments aim at benchmarking hydrocodes simulations and ablator instabilities growth in conditions relevant to ignition in the framework of the Laser MégaJoule [C. Cavailler, Plasma Phys. Controlled Fusion 47, 389 (2005)]. The modulated samples under study were made of germanium-doped plastic (CHGe), which is the nominal ablator for future ignition experiments. The incident x-ray drive was provided using rugby-shaped hohlraums [M. Vandenboomgaerde, J. Bastian, A. Casner et al., Phys. Rev. Lett. 99, 065004 (2007)] and was characterized by means of absolute time-resolved soft x-ray power measurements through a dedicated diagnostic hole, shock breakout data and one-dimensional and two-dimensional (2D) side-on radiographies. All these independent x-ray drive diagnostics lead to an actual on-foil flux that is about 50% smaller than laser-entrance-hole measurements. The experimentally inferred flux is used to simulate experimental optical depths obtained from face-on radiographies for an extensive set of initial conditions: front-side single-mode (wavelength λ =35, 50, and 70 μm) and two-mode perturbations (wavelength λ =35 and 70 μm, in phase or in opposite phase). Three-dimensional pattern growth is also compared with the 2D case. Finally the case of the feedthrough mechanism is addressed with rear-side modulated foils.

  12. Inertial confinement fusion using hohlraum radiation generated by heavy-ion clusters

    SciTech Connect

    Tahir, N.A.; Lutz, K.; Geb, O.; Maruhn, J.A.; Deutsch, C.; Hoffmann, D.H.

    1997-03-01

    This paper discusses the feasibility of employing heavy-ion cluster beams to generate thermal radiation that can be used to drive inertial fusion capsules. The low charge-to-mass ratio of a cluster may allow the driver beam to be focused to a very small spot size with a radius of the order of 100 {mu}m, while the low energy per nucleon (of the order of 10 keV) may lead to a very short range of the driver particles in the converter material. This would result in high specific power deposition that may lead to a very high conversion efficiency. The problem of cluster stopping in cold matter, as well as in hot dense plasmas has been thoroughly investigated. The conversion efficiency of cluster ions using a low-density gold converter has also been calculated over a wide range of parameters including converter density, converter geometry, and specific power deposition. These calculations have been carried out using a one-dimensional hydrodynamic computer code that includes a multigroup radiation transport scheme [Ramis {ital et al.}, Comput. Phys. Commun. {bold 49}, 475 (1988)]. The problem of symmetrization of this radiation field in a hohlraum with solid gold walls has also been thoroughly investigated using a three-dimensional view factor code. The characteristics of the radiation field obtained by this study are used as input to capsule implosion calculations that are done with a three-temperature radiation-hydrodynamic computer code MEDUSA-KAT [Tahir {ital et al.}, J. Appl. Phys. {bold 60}, 898 (1986)]. A reactor-size capsule which contains 5 mg deuterium{endash}tritium (DT) fuel is used in these calculations. The problem of using a fuel mixture with a substantially reduced tritium content has also been discussed. {copyright} {ital 1997 American Institute of Physics.}

  13. X-ray Conversion Efficiency of high-Z hohlraum wall materials for indirect drive ignition

    SciTech Connect

    Dewald, E; Rosen, M; Glenzer, S H; Suter, L J; Girard, F; Jadaud, J P; Schein, J; Constantin, C G; Neumayer, P; Landen, O

    2008-02-22

    We measure the conversion efficiency of 351 nm laser light to soft x-rays (0.1-5 keV) for Au, U and high Z mixtures 'cocktails' used for hohlraum wall materials in indirect drive ICF. We use spherical targets in a direct drive geometry, flattop laser pulses and laser smoothing with phase plates to achieve constant and uniform laser intensities of 10{sup 14} and 10{sup 15} W/cm{sup 2} over the target surface that are relevant for the future ignition experiments on NIF. The absolute time and spectrally-resolved radiation flux is measured with a multichannel soft x-ray power diagnostic. The conversion efficiency is then calculated by dividing the measured x-ray power by the incident laser power from which the measured laser backscattering losses is subtracted. After {approx}0.5 ns, the time resolved x-ray conversion efficiency reaches a slowly increasing plateau of 95% at 10{sup 14} W/cm{sup 2} laser intensity and of 80% at 10{sup 15} W/cm{sup 2}. The M-band flux (2-5 keV) is negligible at 10{sup 14} W/cm{sup 2} reaching {approx}1% of the total x-ray flux for all target materials. In contrast, the M-band flux is significant and depends on the target material at 10{sup 15} W/cm{sup 2} laser intensity, reaching values between 10% of the total flux for U and 27% for Au. Our LASNEX simulations show good agreement in conversion efficiency and radiated spectra with data when using XSN atomic physics model and a flux limiter of 0.15, but they underestimate the generated M-band flux.

  14. Indirect drive ablative Rayleigh-Taylor experiments with rugby hohlraums on OMEGA

    SciTech Connect

    Casner, A.; Galmiche, D.; Huser, G.; Jadaud, J.-P.; Liberatore, S.; Vandenboomgaerde, M.

    2009-09-15

    Results of ablative Rayleigh-Taylor instability growth experiments performed in indirect drive on the OMEGA laser facility [T. R. Boehly, D. L. Brown, S. Craxton et al., Opt. Commun. 133, 495 (1997)] are reported. These experiments aim at benchmarking hydrocodes simulations and ablator instabilities growth in conditions relevant to ignition in the framework of the Laser MegaJoule [C. Cavailler, Plasma Phys. Controlled Fusion 47, 389 (2005)]. The modulated samples under study were made of germanium-doped plastic (CHGe), which is the nominal ablator for future ignition experiments. The incident x-ray drive was provided using rugby-shaped hohlraums [M. Vandenboomgaerde, J. Bastian, A. Casner et al., Phys. Rev. Lett. 99, 065004 (2007)] and was characterized by means of absolute time-resolved soft x-ray power measurements through a dedicated diagnostic hole, shock breakout data and one-dimensional and two-dimensional (2D) side-on radiographies. All these independent x-ray drive diagnostics lead to an actual on-foil flux that is about 50% smaller than laser-entrance-hole measurements. The experimentally inferred flux is used to simulate experimental optical depths obtained from face-on radiographies for an extensive set of initial conditions: front-side single-mode (wavelength {lambda}=35, 50, and 70 {mu}m) and two-mode perturbations (wavelength {lambda}=35 and 70 {mu}m, in phase or in opposite phase). Three-dimensional pattern growth is also compared with the 2D case. Finally the case of the feedthrough mechanism is addressed with rear-side modulated foils.

  15. X-ray conversion efficiency of high-Z hohlraum wall materials for indirect drive ignition

    NASA Astrophysics Data System (ADS)

    Dewald, E. L.; Rosen, M.; Glenzer, S. H.; Suter, L. J.; Girard, F.; Jadaud, J. P.; Schein, J.; Constantin, C.; Wagon, F.; Huser, G.; Neumayer, P.; Landen, O. L.

    2008-07-01

    The conversion efficiency of 351nm laser light to soft x rays (0.1-5keV) was measured for Au, U, and high Z mixture "cocktails" used as hohlraum wall materials in indirect drive fusion experiments. For the spherical targets in a direct drive geometry, flattop laser pulses and laser smoothing with phase plates are employed to achieve constant and uniform laser intensities of 1014 and 1015W/cm2 over the target surface that are relevant for the future ignition experiments at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)]. The absolute time and spectrally resolved radiation flux is measured with a multichannel soft x-ray power diagnostic. The conversion efficiency is then calculated by dividing the measured x-ray power by the incident laser power from which the measured laser backscattering losses are subtracted. After ˜0.5ns, the time resolved x-ray conversion efficiency reaches a slowly increasing plateau of 95% at 1014W/cm2 laser intensity and of 80% at 1015W/cm2. The M-band flux (2-5keV) is negligible at 1014W/cm2 reaching ˜1% of the total x-ray flux for all target materials. In contrast, the M-band flux is significant and depends on the target material at 1015W/cm2 laser intensity, reaching values between 10% of the total flux for U and 27% for Au. LASNEX simulations [G. B. Zimmerman and W. L. Kruer, Comm. Plasma Phys. Contr. Fusion 2, 51 (1975)] show good agreement in conversion efficiency and radiated spectra with data when using XSN atomic physics model and a flux limiter of 0.15, but they underestimate the generated M-band flux.

  16. Symmetry control using beam phasing in ~0.2 NIF scale high temperature Hohlraum experiment on OMEGA

    SciTech Connect

    Delamater, Norman D; Wilson, Goug C; Kyrala, George A; Seifter, Achim; Hoffman, N M; Dodd, E; Glebov, V

    2009-01-01

    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 16.5kJ. 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 would be the first demonstration of beam phasing for implosions in such '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 phasing and which also agree well with post processed hydro code calculations. Time resolved hard x-ray data has been obtained and it was found that the hard x-rays are correlated mainly with the low angle 21{sup o} degree cone.

  17. The radiation temperature and M-band fraction inside hohlraum on the SGIII-prototype laser facility

    SciTech Connect

    Yi Huo, Wen; Lan, Ke; Li, Yongsheng; Li, Xin; Wu, Changshu; Ren, Guoli; Zhao, Yiqing; Zou, Shiyang; Zheng, Wudi; Gu, Peijun; Wang, Min; Yang, Dong; Li, Sanwei; Yi, Rongqing; Jiang, Xiaohua; Song, Tianming; Li, Zhichao; Guo, Liang; Liu, Yonggang; Zhan, Xiayu; and others

    2014-02-15

    The radiation temperature T{sub R} and M-band fraction f{sub M} inside the vacuum Au hohlraum have been experimentally determined by a shock wave technique and a broadband soft x-ray spectrometer (SXS) on the SGIII-prototype laser facility. From the results of the shock wave technique, T{sub R} is about 202 eV, and f{sub M} is about 9% for the hohlraums driven by a 1 ns flattop pulse of 6 kJ laser energy. The Continuous Phase Plate (CPP) for beam smoothing is applied in the experiment, which increases T{sub R} to 207 eV while has almost no influence on f{sub M}. Comparisons between the results from the two kinds of technologies show that T{sub R} from the shock wave technique is lower than that from SXS whether with CPP or not. However, f{sub M} from the shock wave technique is consistent with that from SXS without CPP, but obviously lower than the SXS's result with CPP. The preheat effect on exterior surface of witness plate is reduced by thicker thickness of witness plate designed for higher laser driven energy.

  18. The radiation temperature and M-band fraction inside hohlraum on the SGIII-prototype laser facility

    NASA Astrophysics Data System (ADS)

    Yi Huo, Wen; Yang, Dong; Lan, Ke; Li, Sanwei; Li, Yongsheng; Li, Xin; Wu, Changshu; Ren, Guoli; Zhao, Yiqing; Zou, Shiyang; Zheng, Wudi; Gu, Peijun; Wang, Min; Yi, Rongqing; Jiang, Xiaohua; Song, Tianming; Li, Zhichao; Guo, Liang; Liu, Yonggang; Zhan, Xiayu; Wang, Feng; Peng, Xiaoshi; Zhang, Huan; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2014-02-01

    The radiation temperature TR and M-band fraction fM inside the vacuum Au hohlraum have been experimentally determined by a shock wave technique and a broadband soft x-ray spectrometer (SXS) on the SGIII-prototype laser facility. From the results of the shock wave technique, TR is about 202 eV, and fM is about 9% for the hohlraums driven by a 1 ns flattop pulse of 6 kJ laser energy. The Continuous Phase Plate (CPP) for beam smoothing is applied in the experiment, which increases TR to 207 eV while has almost no influence on fM. Comparisons between the results from the two kinds of technologies show that TR from the shock wave technique is lower than that from SXS whether with CPP or not. However, fM from the shock wave technique is consistent with that from SXS without CPP, but obviously lower than the SXS's result with CPP. The preheat effect on exterior surface of witness plate is reduced by thicker thickness of witness plate designed for higher laser driven energy.

  19. Low-foot rugby hohlraum experiments on the NIF: Wall-gas mix and a connection with missing x-ray drive energy?

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Ross, J. Steven; Schneider, Marilyn; Jones, Oggie; Milovich, Jose; Moody, John

    2014-10-01

    Rugby-shaped hohlraums on the NIF have shown strong symmetry anomalies when simulated with the high-flux model. The wall-gas interface is Rayleigh-Taylor unstable and may lead to the formation of a late-time mix layer that impedes inner- cone propagation, resulting in a drive asymmetry on the capsule. Due to the rugby curvature near the laser entrance hole, the effect of mix may be more pronounced than in cylinders. At the same time a persistent pattern of 15--25% missing energy has been inferred in gas-filled hohlraums (ρ >= 0 . 96 mg/cc). A possible physical connection between formation of a mix layer and the plasma adiabatic lapse rate, where a temperature-gradient reversal is predicted to occur, is explored. Such a profile reversal, in turn, hinders electron conduction to the dense (ρ > 0 . 2 g/cc) Au region responsible for ~900 eV drive x-ray emission, leading to a hotter coronal plasma and reduced hohlraum efficiency. Remedial measures for recovering the loss in hohlraum efficiency through the use of higher-Z gas fills are explored. Prepared by LLNL under Contract DE-AC52-07NA27344.

  20. Uranium hohlraum with an ultrathin uranium-nitride coating layer for low hard x-ray emission and high radiation temperature

    NASA Astrophysics Data System (ADS)

    Guo, Liang; Ding, Yongkun; Xing, Pifeng; Li, Sanwei; Kuang, Longyu; Li, Zhichao; Yi, Taimin; Ren, Guoli; Wu, Zeqing; Jing, Longfei; Zhang, Wenhai; Zhan, Xiayu; Yang, Dong; Jiang, Baibin; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Li, Yongsheng; Liu, Jie; Huo, Wenyi; Lan, Ke

    2015-11-01

    An ultrathin layer of uranium nitrides (UN) has been coated on the inner surface of depleted uranium hohlraum (DUH), which has been proven by our experiment to prevent the oxidization of uranium (U) effectively. Comparative experiments between the novel depleted uranium hohlraum and pure golden (Au) hohlraum are implemented on an SGIII-prototype laser facility. Under a laser intensity of 6 × 1014 W cm-2, we observe that the hard x-ray (hν \\gt 1.8 keV) fraction of the uranium hohlraum decreases by 61% and the peak intensity of the total x-ray flux (0.1 keV˜5.0 keV) increases by 5%. Radiation hydrodynamic code LARED is used to interpret the above observations. Our result for the first time indicates the advantages of the UN-coated DUH in generating a uniform x-ray source with a quasi-Planckian spectrum, which should have important applications in high energy density physics.

  1. The role of a detailed configuration accounting (DCA) atomic physics package in explaining the energy balance in ignition-scale hohlraums

    NASA Astrophysics Data System (ADS)

    Rosen, M. D.; Scott, H. A.; Hinkel, D. E.; Williams, E. A.; Callahan, D. A.; Town, R. P. J.; Divol, L.; Michel, P. A.; Kruer, W. L.; Suter, L. J.; London, R. A.; Harte, J. A.; Zimmerman, G. B.

    2011-09-01

    In 2009 the National Ignition Campaign (NIC) gas-filled/capsule-imploding hohlraum energetics campaign showed good laser-hohlraum coupling, reasonably high drive, and implosion symmetry control via cross-beam transfer. There were, however, discrepancies with expectations from the standard simulation model including: the level and spectrum of the Stimulated Raman light; the tendency towards pancake-shaped implosions; and drive that exceeded predictions early in the campaign, and lagged those predictions late in the campaign. We review here the origins/development path of the "high flux model" (HFM). The HFM contains two principal changes from the standard model: 1) It uses a detailed configuration accounting (DCA) atomic physics non-local-thermodynamic-equilibrium (NLTE) model, and 2) It uses a generous electron thermal flux limiter, f = 0.15, that is consistent with a non-local electron transport model. Both elements make important contributions to the HFM's prediction of a hohlraum plasma that is cooler than that predicted by the standard model, which uses an NLTE average atom approach, and a value of f = 0.05 for the flux limiter. This cooler plasma is key in eliminating most of the discrepancies between the NIC data and revised expectations based on this new simulation model. The HFM had previously been successfully deployed in correctly modeling Omega Laser illuminated gold sphere x-ray emission data, and NIC empty hohlraum drive. However, when the HFM was first applied to this energetics campaign, the model lacked some credibility/acceptance compared to the standard model, because it actually worsened the discrepancy between the observed hohlraum drive for the 1 MJ class experiments performed late in the campaign and the revised expectation of higher drive based on the HFM. Essentially, the HFM was making a prediction that the laser-hohlraum coupling was less than that assumed at that time. Its credibility was then boosted when a re-evaluation of the laser

  2. Low-adiabat rugby hohlraum experiments on the National Ignition Facility: Comparison with high-flux modeling and the potential for gas-wall interpenetration

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Ross, J. Steven; Milovich, Jose L.; Schneider, Marilyn; Storm, Erik; Callahan, Debra A.; Hinkel, Denise; Lasinski, Barbara; Meeker, Don; Michel, Pierre; Moody, John; Strozzi, David

    2014-11-01

    Rugby-shaped gold hohlraums driven by a nominal low-adiabat laser pulse shape have been tested on the National Ignition Facility. The rugby affords a higher coupling efficiency than a comparably sized cylinder hohlraum or, alternatively, improved drive symmetry and laser beam clearances for a larger hohlraum with similar cylinder wall area and laser energy. A first (large rugby hohlraum) shot at low energy (0.75 MJ) to test laser backscatter resulted in a moderately oblate CH capsule implosion, followed by a high energy shot (1.3 MJ) that gave a highly oblate compressed core according to both time-integrated and -resolved x-ray images. These implosions used low wavelength separation (1.0 Å) between the outer and inner cones to provide an alternative platform free of significant cross-beam energy transfer for simplified hohlraum dynamics. Post-shot 2- and 3-D radiation-hydrodynamic simulations using the high-flux model [M. D. Rosen et al., High Energy Density Phys. 7, 180 (2011)], however, give nearly round implosions for both shots, in striking contrast with observations. An analytic assessment of Rayleigh-Taylor hydrodynamic instability growth on the gold-helium gas-fill interface shows the potential for significant linear growth, saturation and transition to a highly nonlinear state. Candidate seeds for instability growth include laser speckle during the early-time laser picket episode in the presence of only partial temporal beam smoothing (1-D smoothing by spectral dispersion and polarization smoothing) and intensity modulations from quad-to-quad and beam overlap. Radiation-hydrodynamic 2-D simulations adapted to include a dynamic fall-line mix model across the unstable Au-He interface show good agreement with the observed implosion symmetry for both shots using an interface-to-fall-line penetration fraction of 100%. Physically, the potential development of an instability layer in a rugby hohlraum is tantamount to an enhanced wall motion leading to hindered

  3. Low-adiabat rugby hohlraum experiments on the National Ignition Facility: Comparison with high-flux modeling and the potential for gas-wall interpenetration

    SciTech Connect

    Amendt, Peter Ross, J. Steven; Milovich, Jose L.; Schneider, Marilyn; Storm, Erik; Callahan, Debra A.; Hinkel, Denise; Lasinski, Barbara; Meeker, Don; Michel, Pierre; Moody, John; Strozzi, David

    2014-11-15

    Rugby-shaped gold hohlraums driven by a nominal low-adiabat laser pulse shape have been tested on the National Ignition Facility. The rugby affords a higher coupling efficiency than a comparably sized cylinder hohlraum or, alternatively, improved drive symmetry and laser beam clearances for a larger hohlraum with similar cylinder wall area and laser energy. A first (large rugby hohlraum) shot at low energy (0.75 MJ) to test laser backscatter resulted in a moderately oblate CH capsule implosion, followed by a high energy shot (1.3 MJ) that gave a highly oblate compressed core according to both time-integrated and –resolved x-ray images. These implosions used low wavelength separation (1.0 Å) between the outer and inner cones to provide an alternative platform free of significant cross-beam energy transfer for simplified hohlraum dynamics. Post-shot 2- and 3-D radiation-hydrodynamic simulations using the high-flux model [M. D. Rosen et al., High Energy Density Phys. 7, 180 (2011)], however, give nearly round implosions for both shots, in striking contrast with observations. An analytic assessment of Rayleigh-Taylor hydrodynamic instability growth on the gold–helium gas-fill interface shows the potential for significant linear growth, saturation and transition to a highly nonlinear state. Candidate seeds for instability growth include laser speckle during the early-time laser picket episode in the presence of only partial temporal beam smoothing (1-D smoothing by spectral dispersion and polarization smoothing) and intensity modulations from quad-to-quad and beam overlap. Radiation-hydrodynamic 2-D simulations adapted to include a dynamic fall-line mix model across the unstable Au-He interface show good agreement with the observed implosion symmetry for both shots using an interface-to-fall-line penetration fraction of 100%. Physically, the potential development of an instability layer in a rugby hohlraum is tantamount to an enhanced wall motion leading to

  4. Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

    SciTech Connect

    Amendt, P; Cerjan, C; Hamza, A; Hinkel, D; Milovich, J L; Robey, H F

    2006-10-26

    The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) targets as a complementary path to the cryogenic baseline approach. Expected benefits of DS ignition targets include non-cryogenic deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma mediated laser backscatter, low threshold ignition temperatures ({approx} 4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances, and minimal (two-) shock timing requirements. On the other hand, DS ignition presents several formidable challenges, encompassing room-temperature containment of high-pressure DT ({approx} 790 atm) in the inner shell, strict concentricity requirements on the two shells (< 3 {micro}m), development of nano-porous (<100 nm) low-density (<100 mg/cc) metallic foams for structural support of the inner shell and hydrodynamic instability mitigation, and effective control of hydrodynamic instabilities on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition designs and required materials-science advances at the nanoscale are described herein. Two new ignition designs that use rugby-shaped vacuum hohlraums are presented which utilize either 1 MJ or 2 MJ of laser energy at 3{omega}. The capability of the NIF to generate the requested reverse-ramp pulse shape for DS ignition is expected to be comparable to the planned high-contrast ({approx}100) pulse-shape at 1.8 MJ for the baseline cryogenic target. Nano-crystalline, high-strength, Au-Cu alloy inner shells are under development using electrochemical deposition over a glass mandrel, exhibiting tensile strengths well in excess of 790 atm. Novel, low-density (85 mg/cc) copper foams have recently been demonstrated using 10 mg/cc SiO{sub 2} nano-porous aerogels with suspended Cu particles. A prototype demonstration of an ignition DS is planned for 2008, incorporating the needed novel nano-materials science developments and the

  5. Toggling between single and multi-beam effects on Stimulated Raman Scattering in a NIF hohlraum plasma

    NASA Astrophysics Data System (ADS)

    Moody, J. D.; Strozzi, D. J.; Divol, L.; Michel, P.; Ralph, J.; Berger, R. L.; Kirkwood, R. K.; Robey, H.; Landen, O. L.; Lepape, S.; Ross, S.; MacGowan, B. J.; Williams, E. A.; Glenzer, S. H.; Nikroo, A.

    2012-10-01

    We have developed a method for studying single and multi-beam laser-plasma interactions (LPI) in a NIF hohlraum plasma. This method utilizes toggling combinations of beams on and off during the time of high (partly saturated) stimulated Raman backscattering (SRS) and measuring the effects on the SRS. We find that during the high-intensity part of the laser pulse SRS saturates at about 10 - 20% reflectivity for single and multi-beam interactions. In addition, we can place limits on the cross-beam energy transfer and show that re-amplification is small due to multiple beam effects. Spectral measurements indicate that toggling beams creates a <=10% change in the plasma temperature. These results are important for developing models of multi-beam intereactions. We will describe the backscatter measurements and simple models used to constrain the multi-beam effects.

  6. Re-Assessing the Maximum Allowed Infrared (IR) Power for Enchanced Layering in a Conduction Dominated Cryogenic NIF-Scale Hohlraum

    SciTech Connect

    Kozioziemski, B J

    2003-08-11

    Recent measurements of the infrared (IR) absorption coefficient of CH and CD capsules differ significantly from earlier estimated values from thin flat samples. The optimum wavelength for IR enhanced layering of DT and D{sub 2} ice layers inside of a NIF scale hohlraum depends on the relative ice and capsule absorption coefficients. This update of a previous memo shows the maximum ice heating with IR as a function of ice and capsule absorption instead of at discrete wavelengths. Also discussed is the leverage of other parameters, such as the IR absorption of the hohlraum wall and thermal conductivities of the support rods and exchange gas. The most likely capsule and ice absorption values limit the IR heating to between 2-7 Q{sub DT}. We find most leverage of the IR heating comes from increasing the ice to capsule absorption ratio. As before, this is the conduction only limit to IR, with convection potentially playing a large role.

  7. Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li{sup +} ion beam-driven hohlraums

    SciTech Connect

    Fehl, D.L.; Chandler, G.A.; Biggs, F.; Dukart, R.J.; Moats, A.R.; Leeper, R.J.

    1996-07-01

    X-ray-producing hohlraums are being studied as indirect drives for Inertial Confinement Fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The UFO unfold code and its suite of auxiliary functions were used extensively in obtaining time- resolved x-ray spectra and radiation temperatures from this diagnostic. UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies ({le} 100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time-history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum.

  8. Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li{sup +} ion beam-driven hohlraums

    SciTech Connect

    Fehl, D.L.; Chandler, G.A.; Biggs, F.; Dukart, R.J.; Moats, A.R.; Leeper, R.J.

    1997-01-01

    X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively in obtaining time-resolved x-ray spectra and radiation temperatures from this diagnostic. The UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies ({le}100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time{endash}history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum. {copyright} {ital 1997 American Institute of Physics.}

  9. Performance of Beryllium Targets with Full-scale Capsules in Low-fill 6.72-mm Hohlraums on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Simakov, A. N.; Yi, S. A.; Kline, J. L.; Kyrala, G. A.; Loomis, E. N.; Wilson, D. C.; Perry, T. S.; Batha, S. H.; Dewald, E. L.; Ralph, J. E.; Strozzi, D. J.

    2016-10-01

    When used with full-size beryllium (Be) capsules, high-fill 5.75-mm hohlraums exhibit significant drive degradation via laser backscatter and ``missing energy''. Also, hard to simulate cross-beam energy transfer (CBET) must be used to control the implosion symmetry. Low-fill (<=0.6 mg/cm3) 6.72-mm hohlraums offer improved drive efficiency and the symmetry tunability without the CBET. In FY16, we carried out an exploratory campaign to evaluate performance of full-size Be capsules in such hohlraums. Specifically, we have performed a fill-density scan with a three-shock, 9.5-ns pulse and found that an appropriate laser beam repointing and outer-quad splitting results in approximately 5% laser backscatter at fill densities <=0.3 mg/cm3, with the implosion becoming less oblate as the fill-density decreases. We also plan to perform an implosion with a lower-foot, 12.6-ns pulse, to observe a more prolate symmetry. Work supported by the US Department of Energy.

  10. Electron temperature measurements inside the ablating plasma of gas-filled hohlraums at the National Ignition Facility

    SciTech Connect

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brown, G. V.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; Regan, S. P.; Jaquez, J.; Huang, H.; Hansen, S. B.

    2016-05-15

    The first measurement of the electron temperature (T{sub e}) inside a National Ignition Facility hohlraum is obtained using temporally resolved K-shell X-ray spectroscopy of a mid-Z tracer dot. Both isoelectronic- and interstage-line ratios are used to calculate the local T{sub e} via the collisional–radiative atomic physics code SCRAM [Hansen et al., High Energy Density Phys 3, 109 (2007)]. The trajectory of the mid-Z dot as it is ablated from the capsule surface and moves toward the laser entrance hole (LEH) is measured using side-on x-ray imaging, characterizing the plasma flow of the ablating capsule. Data show that the measured dot location is farther away from the LEH in comparison to the radiation-hydrodynamics simulation prediction using HYDRA [Marinak et al., Phys. Plasmas 3, 2070 (1996)]. To account for this discrepancy, the predicted simulation T{sub e} is evaluated at the measured dot trajectory. The peak T{sub e}, measured to be 4.2 keV ± 0.2 keV, is ∼0.5 keV hotter than the simulation prediction.

  11. Electron temperature measurements inside the ablating plasma of gas-filled hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brown, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.

    2016-05-01

    The first measurement of the electron temperature (Te) inside a National Ignition Facility hohlraum is obtained using temporally resolved K-shell X-ray spectroscopy of a mid-Z tracer dot. Both isoelectronic- and interstage-line ratios are used to calculate the local Te via the collisional-radiative atomic physics code SCRAM [Hansen et al., High Energy Density Phys 3, 109 (2007)]. The trajectory of the mid-Z dot as it is ablated from the capsule surface and moves toward the laser entrance hole (LEH) is measured using side-on x-ray imaging, characterizing the plasma flow of the ablating capsule. Data show that the measured dot location is farther away from the LEH in comparison to the radiation-hydrodynamics simulation prediction using HYDRA [Marinak et al., Phys. Plasmas 3, 2070 (1996)]. To account for this discrepancy, the predicted simulation Te is evaluated at the measured dot trajectory. The peak Te, measured to be 4.2 keV ± 0.2 keV, is ˜0.5 keV hotter than the simulation prediction.

  12. The Kelvin-Helmholtz instability in National Ignition Facility hohlraums as a source of gold-gas mixing

    SciTech Connect

    Vandenboomgaerde, M.; Bonnefille, M.; Gauthier, P.

    2016-05-15

    Highly resolved radiation-hydrodynamics FCI2 simulations have been performed to model laser experiments on the National Ignition Facility. In these experiments, cylindrical gas-filled hohlraums with gold walls are driven by a 20 ns laser pulse. For the first time, simulations show the appearance of Kelvin-Helmholtz (KH) vortices at the interface between the expanding wall material and the gas fill. In this paper, we determine the mechanisms which generate this instability: the increase of the gas pressure around the expanding gold plasma leads to the aggregation of an over-dense gold layer simultaneously with shear flows. At the surface of this layer, all the conditions are met for a KH instability to grow. Later on, as the interface decelerates, the Rayleigh-Taylor instability also comes into play. A potential scenario for the generation of a mixing zone at the gold-gas interface due to the KH instability is presented. Our estimates of the Reynolds number and the plasma diffusion width at the interface support the possibility of such a mix. The key role of the first nanosecond of the laser pulse in the instability occurrence is also underlined.

  13. Impact of acute stress on antimicrobial polypeptides mRNA copy number in several tissues of marine sea bass (Dicentrarchus labrax)

    PubMed Central

    2011-01-01

    Background In comparison to higher vertebrates, fish are thought to rely heavily on innate immune system for initial protection against pathogen invasion because their acquired immune system displays a considerably poor immunological memory, and short-lived secondary response. The endogenous antimicrobial polypeptides (AMPPs) directly and rapidly killing pathogens such as bacteria, fungi, parasites, and viruses are included within the realm of innate defenses. In addition to piscidins, AMPPs that in recent years have been shown to be commonly linked to innate defense, are histones and their polypeptide fragments, and peptides derived from the respiratory protein hemoglobin. There is evidence that a number of stresses lead to significant regulation of AMPPs and thus their monitoring could be a highly sensitive measure of health status and risk of an infectious disease outbreak, which is a major impediment to the continued success of virtually all aquaculture enterprises and is often the most significant cause of economic losses. Results We firstly isolated and deposited in Genbank database the cDNA sequences encoding for hemoglobin-β-like protein (Hb-LP) [GeneBank: JN410659], H2B histone-like protein 1 (HLP1) GenBank: JN410660], and HLP2 [GenBank: JN410661]. The "de novo" prediction of the three-dimensional structures for each protein is presented. Phylogenetic trees were constructed on Hb-LP, HLP1, and HLP2 sequences of sea bass and those of other teleost, avian, reptiles, amphibian and mammalian species. We then used real time RT-PCR technology to monitor for the first time in sea bass, dynamic changes in mRNA copy number of Hb-LP, HLP1, HLP2, and dicentracin in gills, skin, eyes, stomach and proximal intestine in response to acute crowding/confinement stress. We showed that acute crowding stress induces an increase in the expression levels of the aforementioned genes, in gills and skin of sea bass, but not in other tissues, and that this expression patterns are

  14. On a statistical scattering model to explain capsule implosion symmetry in vacuum Hohlraums with radiation temperatures of order 100 eV

    SciTech Connect

    Goldman, Sanford R; Kyrala, George A; Dodd, Evan S; Grondalski, John P; Hoffman, Nelson M; Rose, Harvey A; Seifter, Achim

    2009-01-01

    We apply a statistical scattering model of laser ray propagation to obtain improved agreement with measurements for capsule emission symmetry in one of three sets of experiments. Linearized post-processing of the simulations for amplification of a variety of plasma instabilities, coupled with an accounting for intensity seed perturbations in the laser beams suggests that thermal filamentation can cause the density fluctuations. Although this mechanism does not appear to be significant in the remaining two series, its identification adds to the knowledge base in the use of symmetry capsules to measure hohlraum drive asymmetry.

  15. Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse

    SciTech Connect

    Kirkwood, R K; Milovich, J; Bradley, D K; Schmitt, M; Goldman, S R; Kalantar, D H; Meeker, D; Jones, O S; Pollaine, S M; Amendt, P A; Dewald, E; Edwards, J; Landen, O L; Nikroo, A

    2008-07-28

    A necessary condition for igniting indirectly-driven inertial confinement fusion (ICF) spherical capsules on the National Ignition Facility (NIF) is controlling drive flux asymmetry to the 1% level time-integrated over the pulse and with < 10%/ns swings during the pulse [J. D. Lindl et al., 'The Physics Basis for Ignition using Indirect Drive Targets on the National Ignition Facility', Physics of Plasmas 11, 339 (2003)]. While drive symmetry during the first 2 ns of the pulse can be inferred by using the re-emission pattern from a surrogate high Z sphere [E. Dewald et al. to be published in Rev. Sci. Inst.] and symmetry during the last 5 ns inferred from the shape of fully imploded capsules [A. Hauer, N. Delamater, D. Ress et al. Rev. Sci. Instrum. 66, 672-7 (1995)], the midportion ({approx} 2-10 ns) has been shown to be amenable to detection by the in-flight shape of x-ray backlit thin shell capsules [Pollaine et. al., Physics of Plasmas 8 2357 (2001)]. In this paper, we present sensitivity studies conducted on the University of Rochester's OMEGA laser of the thin shell symmetry measurement technique at near NIF-scale for two candidate capsule ablator materials, Ge-doped CH and Cu-doped Be. These experiments use both point and area backlighting to cast 4.7 keV radiographs of thin 1.4 mm initial-diameter Ge-doped CH and Cu-doped Be shells when converged a factor of {approx} 0.5 x in radius. Distortions in the position of the transmission limb of the shells resulting from drive asymmetries are measured to an accuracy of a few {micro}ms, meeting requirements. The promising results to date allow us to compare measured and predicted distortions and by inference drive asymmetries for the first 4 asymmetry modes as a function of hohlraum illumination conditions.

  16. A high-speed two-frame, 1-2 ns gated X-ray CMOS imager used as a hohlraum diagnostic on the National Ignition Facility (invited).

    PubMed

    Chen, Hui; Palmer, N; Dayton, M; Carpenter, A; Schneider, M B; Bell, P M; Bradley, D K; Claus, L D; Fang, L; Hilsabeck, T; Hohenberger, M; Jones, O S; Kilkenny, J D; Kimmel, M W; Robertson, G; Rochau, G; Sanchez, M O; Stahoviak, J W; Trotter, D C; Porter, J L

    2016-11-01

    A novel x-ray imager, which takes time-resolved gated images along a single line-of-sight, has been successfully implemented at the National Ignition Facility (NIF). This Gated Laser Entrance Hole diagnostic, G-LEH, incorporates a high-speed multi-frame CMOS x-ray imager developed by Sandia National Laboratories to upgrade the existing Static X-ray Imager diagnostic at NIF. The new diagnostic is capable of capturing two laser-entrance-hole images per shot on its 1024 × 448 pixels photo-detector array, with integration times as short as 1.6 ns per frame. Since its implementation on NIF, the G-LEH diagnostic has successfully acquired images from various experimental campaigns, providing critical new information for understanding the hohlraum performance in inertial confinement fusion (ICF) experiments, such as the size of the laser entrance hole vs. time, the growth of the laser-heated gold plasma bubble, the change in brightness of inner beam spots due to time-varying cross beam energy transfer, and plasma instability growth near the hohlraum wall.

  17. A high-speed two-frame, 1-2 ns gated X-ray CMOS imager used as a hohlraum diagnostic on the National Ignition Facility (invited)

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Palmer, N.; Dayton, M.; Carpenter, A.; Schneider, M. B.; Bell, P. M.; Bradley, D. K.; Claus, L. D.; Fang, L.; Hilsabeck, T.; Hohenberger, M.; Jones, O. S.; Kilkenny, J. D.; Kimmel, M. W.; Robertson, G.; Rochau, G.; Sanchez, M. O.; Stahoviak, J. W.; Trotter, D. C.; Porter, J. L.

    2016-11-01

    A novel x-ray imager, which takes time-resolved gated images along a single line-of-sight, has been successfully implemented at the National Ignition Facility (NIF). This Gated Laser Entrance Hole diagnostic, G-LEH, incorporates a high-speed multi-frame CMOS x-ray imager developed by Sandia National Laboratories to upgrade the existing Static X-ray Imager diagnostic at NIF. The new diagnostic is capable of capturing two laser-entrance-hole images per shot on its 1024 × 448 pixels photo-detector array, with integration times as short as 1.6 ns per frame. Since its implementation on NIF, the G-LEH diagnostic has successfully acquired images from various experimental campaigns, providing critical new information for understanding the hohlraum performance in inertial confinement fusion (ICF) experiments, such as the size of the laser entrance hole vs. time, the growth of the laser-heated gold plasma bubble, the change in brightness of inner beam spots due to time-varying cross beam energy transfer, and plasma instability growth near the hohlraum wall.

  18. Experiments and Numerical Simulation on a New Hohlraum Configuration with Planar Wire Array Sources at the 1.7 MA Zebra Generator

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Chuvatin, A. S.; Rudakov, L. I.; Safronova, A. S.; Esaulov, A. A.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Weller, M. E.; Keim, S. F.; Stafford, A.; Jones, B.; Vesey, R. A.

    2012-10-01

    In new hohlraum configuration, multiple mm-size planar wire array (PWA) sources surround a central cavity [B. Jones et al., PRL, v.104 (2010)]. This might provide a hotter hohlraum for ICF than the prior double-ended scheme with cylindrical arrays. The current redistribution in two magnetically decoupled compact Z-pinches (0.75-0.82 MA each) was demonstrated at 1.7 MA UNR Zebra generator. Yield measurements from two cages with PWA sources show that such plasma dissipates the magnetic energy at stagnation as a resistor. For the first time, strong EUV radiation, that time-correlated with sub-keV source bursts, was registered from central cavity. The experimental cavity radiation temperature of 37-45 eV correlates well with 39 eV from VisRaD code (PRISM Co.) simulation. First results of new configuration optimization are reported. The possible applications for 30-60 MA ICF experiments are discussed. This work was supported by NNSA under DOE Coop. Agr. DE-FC52-06NA27586, 06NA27588, 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 Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. The effect of hohlraum drive asymmetry on the observed in-flight momentum and hot spot emission non-uniformity in ICF implosions

    NASA Astrophysics Data System (ADS)

    Pak, Arthur; Field, J. E.; Kritcher, A.; Nora, R.; Berzak Hopkins, L. F.; Divol, L.; Khan, S. F.; Ma, T.; Tommasini, R.; Bradley, D. K.; Callahan, D.; Hinkel, D.; Hurricane, O. A.; Jones, O. S.; MacKinnon, A. J.; MacLaren, S. A.; Meezan, N. B.; Moody, J.; Patel, P.; Robey, H. F.; Smalyuk, V. A.; Spears, B. K.; Town, R. P. J.; Edwards, M. J.; LLNL Team

    2015-11-01

    At the National Ignition Facility indirectly driven inertial confinement fusion experiments are being conducted. In order to maximize the efficiency at which kinetic energy of the capsule ablator and fuel is converted to internal hot spot energy, asymmetries in the shape of the ablator and fuel momentum must be minimized. In this work an overview across different implosion experiments detailing the observed relationship between the in-flight ablator momentum symmetry and factors that modify the hohlraum radiation flux symmetry such as the density of the hohlraum gas fill, laser wavelength separation, and case to capsule ratio will be given. A measurement of the ablator momentum asymmetry at peak velocity can be made using the two-dimensional radiographs of the capsule ablator taken in-flight, at radii of 300 to 200 _m. Additionally the relationship between the morphology of the observed in-flight ablator and the x-ray self emission at stagnation will be examined. 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. Use of d-3He proton spectroscopy as a diagnostic of shell rho r in capsule implosion experiments with approximately 0.2 NIF scale high temperature Hohlraums at Omega.

    PubMed

    Delamater, N D; Wilson, D C; Kyrala, G A; Seifter, A; Hoffman, N M; Dodd, E; Singleton, R; Glebov, V; Stoeckl, C; Li, C K; Petrasso, R; Frenje, J

    2008-10-01

    We present the calculations and preliminary results from experiments on the Omega laser facility using d-(3)He filled plastic capsule implosions in gold Hohlraums. These experiments aim to develop a technique to measure shell rho r and capsule unablated mass with proton spectroscopy and will be applied to future National Ignition Facility (NIF) experiments with ignition scale capsules. The Omega Hohlraums are 1900 microm length x 1200 microm diameter and have a 70% laser entrance hole. This is approximately a 0.2 NIF scale ignition Hohlraum and reaches temperatures of 265-275 eV similar to those during the peak of the NIF drive. These capsules can be used as a diagnostic of shell rho r, since the d-(3)He gas fill produces 14.7 MeV protons in the implosion, which escape through the shell and produce a proton spectrum that depends on the integrated rho r of the remaining shell mass. The neutron yield, proton yield, and spectra change with capsule shell thickness as the unablated mass or remaining capsule rho r changes. Proton stopping models are used to infer shell unablated mass and shell rho r from the proton spectra measured with different filter thicknesses. The experiment is well modeled with respect to Hohlraum energetics, neutron yields, and x-ray imploded core image size, but there are discrepancies between the observed and simulated proton spectra.

  1. Early-time radiation flux symmetry optimization and its effect on gas-filled hohlraum ignition targets on the National Ignition Facility

    SciTech Connect

    Milovich, J. L. Dewald, E. L.; Pak, A.; Michel, P.; Town, R. P. J.; Bradley, D. K.; Landen, O.; Edwards, M. J.

    2016-03-15

    Achieving ignition on the National Ignition Facility (NIF) is tied to our ability to control and minimize deviations from sphericity of the capsule implosion. Low-mode asymmetries of the hot spot result from the combined effect of radiation drive asymmetries throughout the laser pulse and initial roughness on the capsule surface. In this paper, we report on simulations and experiments designed to assess, measure, and correct the drive asymmetries produced by the early-time (≈first 2 ns or “picket”) period of the laser pulse. The drive asymmetry during the picket is commonly thought to introduce distortions in the hot-spot shape at ignition time. However, a more subtle effect not previously considered is that it also leads to an asymmetry in shock velocity and timing, thereby increasing the fuel adiabat and reducing the margin for ignition. It is shown via hydrodynamic simulations that minimizing this effect requires that the early-time asymmetry be kept below 7.5% in the second Legendre mode (P{sub 2}), thus keeping the loss of performance margin below ≈10% for a layered implosion. Asymmetries during the picket of the laser pulse are measured using the instantaneous self-emission of a high-Z re-emission sphere in place of an ignition capsule in a hohlraum with large azimuthal diagnostic windows. Three dimensional simulations using the code HYDRA (to capture the effect of non-azimuthal hohlraum features) coupled to a cross-beam energy transfer model [Michel et al., Phys. Plasmas 17, 056305 (2010)] are used to establish the surrogacy of the re-emit target and to assess the early-time drive symmetry. Calculations using this model exhibit the same sensitivity to variations in the relative input powers between the different cones of NIF beams as measured for the “Rev5” CH target [Haan et al., Phys Plasmas 18, 051001 (2011)] and reported by Dewald et al. [Phys. Rev. Lett. 111, 235001 (2013)]. The same methodology applied to recently improved implosions

  2. Early-time radiation flux symmetry optimization and its effect on gas-filled hohlraum ignition targets on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Milovich, J. L.; Dewald, E. L.; Pak, A.; Michel, P.; Town, R. P. J.; Bradley, D. K.; Landen, O.; Edwards, M. J.

    2016-03-01

    Achieving ignition on the National Ignition Facility (NIF) is tied to our ability to control and minimize deviations from sphericity of the capsule implosion. Low-mode asymmetries of the hot spot result from the combined effect of radiation drive asymmetries throughout the laser pulse and initial roughness on the capsule surface. In this paper, we report on simulations and experiments designed to assess, measure, and correct the drive asymmetries produced by the early-time (≈first 2 ns or "picket") period of the laser pulse. The drive asymmetry during the picket is commonly thought to introduce distortions in the hot-spot shape at ignition time. However, a more subtle effect not previously considered is that it also leads to an asymmetry in shock velocity and timing, thereby increasing the fuel adiabat and reducing the margin for ignition. It is shown via hydrodynamic simulations that minimizing this effect requires that the early-time asymmetry be kept below 7.5% in the second Legendre mode (P2), thus keeping the loss of performance margin below ≈10% for a layered implosion. Asymmetries during the picket of the laser pulse are measured using the instantaneous self-emission of a high-Z re-emission sphere in place of an ignition capsule in a hohlraum with large azimuthal diagnostic windows. Three dimensional simulations using the code HYDRA (to capture the effect of non-azimuthal hohlraum features) coupled to a cross-beam energy transfer model [Michel et al., Phys. Plasmas 17, 056305 (2010)] are used to establish the surrogacy of the re-emit target and to assess the early-time drive symmetry. Calculations using this model exhibit the same sensitivity to variations in the relative input powers between the different cones of NIF beams as measured for the "Rev5" CH target [Haan et al., Phys Plasmas 18, 051001 (2011)] and reported by Dewald et al. [Phys. Rev. Lett. 111, 235001 (2013)]. The same methodology applied to recently improved implosions using different

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

    PubMed

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

    2009-10-02

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

  4. Improved hard x-ray (50-80 keV) imaging of hohlraum implosion experiments at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Bachmann, B.; Chow, R.; Palmer, N. E.; Hoover, M.; Huffman, E.; Lee, J. J.; Romano, E.; Kumar, C.; Hulbert, R. D.; Albert, F.; Dewald, E. L.; Divol, L.; Hohenberger, M.; Landen, O. L.; Warrick, A.; Döppner, T.

    2016-09-01

    We recently designed, built and commissioned a new pinhole / filter assembly for the equatorial hard x-ray imager (eHXI) at the National Ignition Facility (NIF). In this paper we describe the design and metrology of the new diagnostic as well as the spectral and spatial response of the hard x-ray detector. The new eHXI assembly has improved the photon collection efficiency along with spectral and spatial resolution by making use of 1D imaging channels and various hard x-ray filters. In addition we added a Ross pair filter set for Au K-alpha emission (67-69 keV). The new eHXI design will improve our understanding of the sourcing of hot electrons, generated in laser-plasma-instabilities, along the vertical hohlraum axis. This information is an important input for simulating and eventually limiting the DT fuel preheat in ICF implosions.

  5. Improving the accuracy of hohlraum simulations by calibrating the `SNB' multigroup diffusion model for nonlocal heat transport against a VFP code

    NASA Astrophysics Data System (ADS)

    Brodrick, Jonathan; Ridgers, Christopher; Dudson, Ben; Kingham, Robert; Marinak, Marty; Patel, Mehul; Umansky, Maxim; Chankin, Alex; Omotani, John

    2016-10-01

    Nonlocal heat transport, occurring when temperature gradients become steep on the scale of the electron mean free path (mfp), has proven critical in accurately predicting ignition-scale hohlraum energetics. A popular approach, and modern alternative to flux limiters, is the `SNB' model. This is implemented in both the HYDRA code used for simulating National Ignition Facility experiments and the CHIC code developed at the CELIA laboratory. We have performed extensive comparisons of the SNB heat flow predictions with two VFP codes, IMPACT and KIPP and found that calibrating the mfp to achieve agreement for a linear problem also improves nonlinear accuracy. Furthermore, we identify that using distinct electron-ion and electron-electron mfp's instead of a geometrically averaged one improves predictive capability when there are strong ionisation (Z) gradients. This work is funded by EPSRC Grant EP/K504178/1.

  6. Preliminary study on expression of antimicrobial peptides in European sea bass (Dicentrarchus labrax) following in vivo infection with Vibrio anguillarum. A time course experiment.

    PubMed

    Meloni, Mauro; Candusso, Sabrina; Galeotti, Marco; Volpatti, Donatella

    2015-03-01

    Antimicrobial polypeptides (AMPPs) are humoral components of the vertebrates and invertebrates innate immune system. Their potent broad spectrum antimicrobial activities have drawn the attention of the scientific community to their potential use not only as an alternative to antibiotics but also as functional targets for immunostimulants in order to enhance the host immunity. Fish synthesize a great number of these peptides but in European sea bass, an important fish species in the Mediterranean aquaculture, only a few AMPPs have been studied and these surveys have highlighted their functional role as predictive markers of stressful conditions. Many aspects concerning AMPP mode of action in the host during bacterial infections are still unknown. In this work a 72 h time course experiment, performed on juvenile sea bass intraperitoneally (i.p.) injected with a sub-lethal dose of Vibrio anguillarum, was aimed to investigate the mRNA expression of four specific AMPP genes and interleukin-1β (IL-1β) in skin, gills, spleen, and head kidney. AMPP genes were: dicentracin (DIC), histone-like protein 1 (HLP-1), histone-like protein 2 (HLP-2) and hemoglobin-like protein (Hb-LP). The delta-delta C(T) method in real-time RT-PCR allowed to gain more knowledge about temporal dynamics, preferential sites of expression as well as immunological and physiological role of these molecular markers. DIC was significantly up-regulated mainly in head kidney at 1.5-3 h post-infection (p.i.). HLP-1 showed an extended-time overexpression in gills and a significant up-regulation in spleen. HLP-2 was interestingly overexpressed in gills at 24 h p.i., while Hb-LP showed a significant up-regulation in skin for all the 72 h trial as well as lower but always significant values either in gills or in spleen. Different was the response of IL-1β that showed a dramatic up-regulation in spleen and head kidney at 8 h p.i. whilst in gills it displayed a severe inhibition. During this survey the i

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    SciTech Connect

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

    2016-07-15

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

  11. Laser parametric instability experiments of a 3ω, 15 kJ, 6-ns laser pulse in gas-filled hohlraums at the Ligne d'Intégration Laser facility

    NASA Astrophysics Data System (ADS)

    Rousseaux, C.; Huser, G.; Loiseau, P.; Casanova, M.; Alozy, E.; Villette, B.; Wrobel, R.; Henry, O.; Raffestin, D.

    2015-02-01

    Experimental investigation of stimulated Raman (SRS) and Brillouin (SBS) scattering have been obtained at the Ligne-d'Intégration-Laser facility (LIL, CEA-Cesta, France). The parametric instabilities (LPI) are driven by firing four laser beamlets (one quad) into millimeter size, gas-filled hohlraum targets. A quad delivers energy on target of 15 kJ at 3ω in a 6-ns shaped laser pulse. The quad is focused by means of 3ω gratings and is optically smoothed with a kinoform phase plate and with smoothing by spectral dispersion-like 2 GHz and/or 14 GHz laser bandwidth. Open- and closed-geometry hohlraums have been used, all being filled with 1-atm, neo-pentane (C5H12) gas. For SRS and SBS studies, the light backscattered into the focusing optics is analyzed with spectral and time resolutions. Near-backscattered light at 3ω and transmitted light at 3ω are also monitored in the open geometry case. Depending on the target geometry (plasma length and hydrodynamic evolution of the plasma), it is shown that, at maximum laser intensity about 9 × 1014 W/cm2, Raman reflectivity noticeably increases up to 30% in 4-mm long plasmas while SBS stays below 10%. Consequently, laser transmission through long plasmas drops to about 10% of incident energy. Adding 14 GHz bandwidth to the laser always reduces LPI reflectivities, although this reduction is not dramatic.

  12. Laser parametric instability experiments of a 3ω, 15 kJ, 6-ns laser pulse in gas-filled hohlraums at the Ligne d'Intégration Laser facility

    SciTech Connect

    Rousseaux, C.; Huser, G.; Loiseau, P.; Casanova, M.; Alozy, E.; Villette, B.; Wrobel, R.; Henry, O.; Raffestin, D.

    2015-02-15

    Experimental investigation of stimulated Raman (SRS) and Brillouin (SBS) scattering have been obtained at the Ligne-d'Intégration-Laser facility (LIL, CEA-Cesta, France). The parametric instabilities (LPI) are driven by firing four laser beamlets (one quad) into millimeter size, gas-filled hohlraum targets. A quad delivers energy on target of 15 kJ at 3ω in a 6-ns shaped laser pulse. The quad is focused by means of 3ω gratings and is optically smoothed with a kinoform phase plate and with smoothing by spectral dispersion-like 2 GHz and/or 14 GHz laser bandwidth. Open- and closed-geometry hohlraums have been used, all being filled with 1-atm, neo-pentane (C{sub 5}H{sub 12}) gas. For SRS and SBS studies, the light backscattered into the focusing optics is analyzed with spectral and time resolutions. Near-backscattered light at 3ω and transmitted light at 3ω are also monitored in the open geometry case. Depending on the target geometry (plasma length and hydrodynamic evolution of the plasma), it is shown that, at maximum laser intensity about 9 × 10{sup 14} W/cm{sup 2}, Raman reflectivity noticeably increases up to 30% in 4-mm long plasmas while SBS stays below 10%. Consequently, laser transmission through long plasmas drops to about 10% of incident energy. Adding 14 GHz bandwidth to the laser always reduces LPI reflectivities, although this reduction is not dramatic.

  13. Dynamic hohlraum experiments on SATURN

    SciTech Connect

    Nash, T.J.; Derzon, M.S.; Allshouse, G.

    1997-08-01

    The authors have imploded a 17.5 mm diameter 120-tungsten-wire array weighing 450 {mu}g/cm onto a 4 mm diameter silicon aerogel foam weighing 650 {mu}g/cm, using the pulsed power driver SATURN. A peak current of 7.0 MA drives a 48 ns implosion to strike time followed by 8 ns of foam compression until stagnation. The tungsten strikes the foam with a 50 cm/{mu}s implosion velocity. Radiation temperatures were measured from the side and along the axis with filtered x-ray diode arrays. There is evidence of radiation trapping by the optically thick tungsten from crystal spectroscopy. The pinch is open to less than a 1 mm diameter as measured by time-resolved x-ray framing cameras. The radiation brightness temperature in the foam reaches 150 eV before the main radiation burst or stagnation.

  14. Ideal Laser Beam Propagation through high temperature ignition hohlraum plasmas

    SciTech Connect

    Froula, D H; Divol, L; Meezan, N; Dixit, S; Moody, J D; Pollock, B B; Ross, J S; Glenzer, S H

    2006-09-20

    We demonstrate that a blue (3{omega}, 351 nm) laser beam with an intensity of 2 x 10{sup 15} W-cm{sup -2} propagates within the original beam cone through a 2-mm long, T{sub e}=3.5 keV high density (n{sub e} = 5 x 10{sup 20} cm{sup -3}) plasma. The beam produced less than 1% total backscatter; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  15. Radiation flux and spectral analysis of the multi-temperature Z dynamic hohlraum

    SciTech Connect

    Lockard, T. E.; Idzorek, G. C.; Tierney, T. E. IV; Watt, R. G.

    2008-10-15

    Experiments performed at the Sandia National Laboratories (SNL) Z-machine, located in Albuquerque, New Mexico produce hot ({approx}220 eV) plasmas. X-ray emission from the plasma is used to drive radiation flow experiments. Our standard plasma diagnostic suite consists of x-ray diodes (XRDs), silicon photodiodes, and nickel thin film bolometers. Small diagnostic holes allow us to view the hot plasma from the side, top axial anode side, and bottom axial cathode side. Computer software has been written to process the raw data to calculate data quality, fold in detector spectral response and experiment geometry for emitted flux, calculate a multidetector spectral unfold, and yield an equivalent time-dependent Planckian temperature profile. Spectral unfolds of our XRD data generally yield a Planckian-like spectrum. In our presentation we will compare our diagnostic techniques, analysis, and results to more accurately characterize spectral unfolds in order to establish better drive conditions for our experiments.

  16. Radiation flux and spectral analysis of the multi-temperature Z dynamic hohlraum.

    PubMed

    Lockard, T E; Idzorek, G C; Tierney, T E; Watt, R G

    2008-10-01

    Experiments performed at the Sandia National Laboratories (SNL) Z-machine, located in Albuquerque, New Mexico produce hot (approximately 220 eV) plasmas. X-ray emission from the plasma is used to drive radiation flow experiments. Our standard plasma diagnostic suite consists of x-ray diodes (XRDs), silicon photodiodes, and nickel thin film bolometers. Small diagnostic holes allow us to view the hot plasma from the side, top axial anode side, and bottom axial cathode side. Computer software has been written to process the raw data to calculate data quality, fold in detector spectral response and experiment geometry for emitted flux, calculate a multidetector spectral unfold, and yield an equivalent time-dependent Planckian temperature profile. Spectral unfolds of our XRD data generally yield a Planckian-like spectrum. In our presentation we will compare our diagnostic techniques, analysis, and results to more accurately characterize spectral unfolds in order to establish better drive conditions for our experiments.

  17. Mitigating stimulated scattering processes in gas-filled Hohlraums via external magnetic fields

    SciTech Connect

    Gong, Tao; Zheng, Jian; Li, Zhichao; Ding, Yongkun; Yang, Dong; Hu, Guangyue; Zhao, Bin

    2015-09-15

    A simple model, based on energy and pressure equilibrium, is proposed to deal with the effect of external magnetic fields on the plasma parameters inside the laser path, which shows that the electron temperature can be significantly enhanced as the intensity of the external magnetic fields increases. With the combination of this model and a 1D three-wave coupling code, the effect of external magnetic fields on the reflectivities of stimulated scattering processes is studied. The results indicate that a magnetic field with an intensity of tens of Tesla can decrease the reflectivities of stimulated scattering processes by several orders of magnitude.

  18. NIF-Scale Hohlraum Asymmetry Studies Using Point-Projection Radiograph of Thin Shells

    SciTech Connect

    Pollaine, S.; Bradley, D.; Landen, O.; Wallace, R.; Jones, O.

    2000-10-06

    Our current OMEGA experimental campaign is developing the thin shell diagnostic for use on NIF with the needed accuracy. The thin shell diagnostic has the advantage of linearity over alternative measurement techniques, so that low-order modes will not corrupt the measurement of high-order modes. Although our random measurement errors are adequate, we need to monitor beam balance and ensure that the thin shells have a uniform thickness.

  19. Neutron-induced reactions in the hohlraum to study reaction in flight neutrons

    NASA Astrophysics Data System (ADS)

    Boswell, M. S.; Elliott, S. R.; Guiseppe, V.; Kidd, M.; Rundberg, B.; Tybo, J.

    2013-04-01

    We are currently developing the physics necessary to measure the Reaction In Flight (RIF) neutron flux from a NIF capsule. A measurement of the RIF neutron flux from a NIF capsule could be used to deduce the stopping power in the cold fuel of the NIF capsule. A foil irradiated at the Omega laser at LLE was counted at the LANL low-background counting facility at WIPP. The estimated production rate of 195Au was just below our experimental sensitivity. We have made several improvements to our counting facility in recent months. These improvements are designed to increase our sensitivity, and include installing two new low-background detectors, and taking steps to reduce noise in the signals.

  20. Ideal Laser-Beam Propagation through High-Temperature Ignition Hohlraum Plasmas

    SciTech Connect

    Froula, D. H.; Divol, L.; Meezan, N. B.; Dixit, S.; Moody, J. D.; Neumayer, P.; Pollock, B. B.; Ross, J. S.; Glenzer, S. H.

    2007-02-23

    We demonstrate that a blue (3{omega}, 351 nm) laser beam with an intensity of 2x10{sup 15} W cm{sup -2} propagates nearly within the original beam cone through a millimeter scale, T{sub e}=3.5 keV high density (n{sub e}=5x10{sup 20} cm{sup -3}) plasma. The beam produced less than 1% total backscatter at these high temperatures and densities; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  1. Ideal laser-beam propagation through high-temperature ignition Hohlraum plasmas.

    PubMed

    Froula, D H; Divol, L; Meezan, N B; Dixit, S; Moody, J D; Neumayer, P; Pollock, B B; Ross, J S; Glenzer, S H

    2007-02-23

    We demonstrate that a blue (3omega, 351 nm) laser beam with an intensity of 2 x 10(15) W cm(-2) propagates nearly within the original beam cone through a millimeter scale, T(e)=3.5 keV high density (n(e)=5 x 10(20) cm(-3)) plasma. The beam produced less than 1% total backscatter at these high temperatures and densities; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  2. Analysis of NIC Cryogenic Layered Experiments via Integrated Hohlraum plus Capsule Post-Shot Simulations

    NASA Astrophysics Data System (ADS)

    Jones, O. S.; Cerjan, C. J.; Eder, D. C.; Springer, P. T.; Clark, D. S.; Marinak, M. M.; Milovich, J. L.; Patel, M. V.; Sepke, S. M.; Suter, L. J.; Thomas, C. A.; Town, R. P. J.; Olson, R. E.

    2012-10-01

    We previously reported a simulation-based semi-empirical model of the NIC layered implosions [1]. In this model input parameters (chiefly laser power) are adjusted so that the simulated capsule's shock timing, time-dependent shell velocity, and imploded core shape closely match experimental measurements. We have applied this model to a growing database of layered implosions. We find that simulated ion temperatures agree well with experiments that are not heavily mixed. The model was able to predict the increase in neutron down-scattered ratio (DSR) that was seen experimentally when the laser peak power was lowered from 420 to 320 TW and extended in time to minimize shell re-expansion (so-called ``no-coasting'' pulse). The DSR correlates with calculated fuel adiabat and suggests that the improved fuel adiabat was the primary reason for the DSR improvement.[0pt] [1] Jones, et al., Phys of Plasma, 19, 056315 (2012)

  3. Optical Mixing in the Strong Coupling Regime: A New Method of Beam Conditioning at Hohlraum LEH and Direct Drive ICF Coronal Plasmas

    NASA Astrophysics Data System (ADS)

    Mardirian, Marine; Afeyan, Bedros; Huller, Stefan; Montgomery, David; Froula, Dustin; Kirkwood, Robert

    2012-10-01

    We will present theoretical and computational results on Brillouin interactions between two beams in co-, counter-, and orthogonal propagation geometries. The beams will be structured (with speckle patterns), the plasma will have inhomogeneous flow including the Mach -1 surface. As the growth rate of the instability surpasses the natural frequency of the ion wave, the strong coupling regime (SCR) is reached, where reactive quasi-modes with intensity dependent frequency shifts result. This is especially true in laser hot spots. We trace the consequences of operations in this regime with different damping rates on the ion acoustic waves. We consider convective and absolute instabilities as well as the design of experiments which could examine these new regimes of instability behavior with new 10 psec time resolved diagnostics. Whether well enough conditioned beams can result after 10's or 100's of pairwise crossings in direct and indirect drive ICF configurations, and whether SRS can thus be strongly suppressed downstream, remains to be demonstrated. But the prospects exist for such new paths to instability control in a staged manner before STUD pulses are implemented.-

  4. Vlasov-Fokker-Planck modeling of plasma near hohlraum walls heated with nanosecond laser pulses calculated using the ray tracing equations

    NASA Astrophysics Data System (ADS)

    Joglekar, Archis; Thomas, Alec

    2013-10-01

    Here, we present 2D numerical modeling of near critical density plasma using a fully implicit Vlasov-Fokker-Planck code, IMPACTA, which includes self-consistent magnetic fields as well as anisotropic electron pressure terms in the expansion of the distribution function, as well as an implementation of the Boris CYLRAD algorithm through a ray tracing add-on package. This allows to model inverse brehmsstrahlung heating as a laser travels through a plasma by solving the ray tracing equations. Generated magnetic fields (eg. the Biermann battery effect) as well as field advection through heat fluxes from the laser heating is shown. Additionally, perturbations in the plasma density profile arise as a result of the high pressures and flows in the plasma. These perturbations in the plasma density affect the path of the laser traveling through the plasma and modify the heating profile accordingly. The interplay between these effects is discussed in this study.

  5. Development of Improved Radiation Drive Environment for High Foot Implosions at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Hinkel, D. E.; Berzak Hopkins, L. F.; Ma, T.; Ralph, J. E.; Albert, F.; Benedetti, L. R.; Celliers, P. M.; Döppner, T.; Goyon, C. S.; Izumi, N.; Jarrott, L. C.; Khan, S. F.; Kline, J. L.; Kritcher, A. L.; Kyrala, G. A.; Nagel, S. R.; Pak, A. E.; Patel, P.; Rosen, M. D.; Rygg, J. R.; Schneider, M. B.; Turnbull, D. P.; Yeamans, C. B.; Callahan, D. A.; Hurricane, O. A.

    2016-11-01

    Analyses of high foot implosions show that performance is limited by the radiation drive environment, i.e., the hohlraum. Reported here are significant improvements in the radiation environment, which result in an enhancement in implosion performance. Using a longer, larger case-to-capsule ratio hohlraum at lower gas fill density improves the symmetry control of a high foot implosion. Moreover, for the first time, these hohlraums produce reduced levels of hot electrons, generated by laser-plasma interactions, which are at levels comparable to near-vacuum hohlraums, and well within specifications. Further, there is a noteworthy increase in laser energy coupling to the hohlraum, and discrepancies with simulated radiation production are markedly reduced. At fixed laser energy, high foot implosions driven with this improved hohlraum have achieved a 1.4 ×increase in stagnation pressure, with an accompanying relative increase in fusion yield of 50% as compared to a reference experiment with the same laser energy.

  6. Indirect drive targets for fusion power

    DOEpatents

    Amendt, Peter A.; Miles, Robin R.

    2016-10-11

    A hohlraum for an inertial confinement fusion power plant is disclosed. The hohlraum includes a generally cylindrical exterior surface, and an interior rugby ball-shaped surface. Windows over laser entrance holes at each end of the hohlraum enclose inert gas. Infrared reflectors on opposite sides of the central point reflect fusion chamber heat away from the capsule. P2 shields disposed on the infrared reflectors help assure an enhanced and more uniform x-ray bath for the fusion fuel capsule.

  7. Status Of Cryogenic Layering For NIF Ignition Targets

    SciTech Connect

    Moody, J D; Kozioziemski, B J; London, R L; Montgomery, D S; Sanchez, J J; Sater, J D; Bittner, D N; Burmann, J A; Jones, R L; Pipes, J; Stefanescu, D

    2005-08-22

    Recent advances in cryogenic layering include the development of a self-contained and self-filling cro hohlraum, application of phase contrast x-ray measurements for ice layer characterization, an ice layer achieved with beta-layering which meets the NIF specification for surface roughness at 1.5 K below the triple point. In addition, recent results on target integration in a hohlraum show effective layer control using heaters on the hohlraum.

  8. [The bacterial nucleoid].

    PubMed

    Gómez-Eichelmann, M C; Camacho-Carranza, R

    1995-01-01

    The bacterial genome is present in the cell within a complex structure, the nucleoid. The nucleoid contains the genomic DNA, and molecules of RNA and proteins. The main proteins of the nucleoid are: RNA polymerase, topoisomerases and the histone-like proteins: HU, H-NS (H1), H, HLP1, IHF and FIS. The DNA molecule in the nucleoid is under helical tension or supercoiling and is organized into 43 +/- 10 topodomains. DNA supercoiling is generated by the activity of the topoisomerases and by DNA-protein interactions. In this review, we analize current knowledge in Escherichia coli about genome organization and proteins of the nucleoid.

  9. The Impact of Maneuver Warfare Strategy/Tactics on the U.S. Marine Corps’ Integrated Air/Ground (MAGTF) Doctrine

    DTIC Science & Technology

    1984-06-22

    that those who don’t quickly "see the light" are fuzzy thinking dinosaurs who are unable to comprehend the lessons of military history . Marine Corps...Marine Corps. 4 :.-. a°-" ., a. • ".°.’ - .- I.P .h.’ HLP1?UUUCLU A I GOVLRNMINT LXPENSL CHAPTER V CONCLUSION Military history is replete with examples of...A I UOVLRNMLN I LXPLNbL Also legion in military history , are examples of equally tragic and severe losses due to the premature abandonment of proven

  10. Laser-Plasma Interactions in Drive Campaign targets on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Hinkel, D. E.; Callahan, D. A.; Moody, J. D.; Amendt, P. A.; Lasinski, B. F.; MacGowan, B. J.; Meeker, D.; Michel, P. A.; Ralph, J.; Rosen, M. D.; Ross, J. S.; Schneider, M. B.; Storm, E.; Strozzi, D. J.; Williams, E. A.

    2016-03-01

    The Drive campaign [D A Callahan et al., this conference] on the National Ignition Facility (NIF) laser [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, R. Al-Ayat, Phys. Plasmas 16, 041006 (2009)] has the focused goal of understanding and optimizing the hohlraum for ignition. Both the temperature and symmetry of the radiation drive depend on laser and hohlraum characteristics. The drive temperature depends on the coupling of laser energy to the hohlraum, and the symmetry of the drive depends on beam-to-beam interactions that result in energy transfer [P. A. Michel, S. H. Glenzer, L. Divol, et al, Phys. Plasmas 17, 056305 (2010).] within the hohlraum. To this end, hohlraums are being fielded where shape (rugby vs. cylindrical hohlraums), gas fill composition (neopentane at room temperature vs. cryogenic helium), and gas fill density (increase of ∼ 150%) are independently changed. Cylindrical hohlraums with higher gas fill density show improved inner beam propagation, as should rugby hohlraums, because of the larger radius over the capsule (7 mm vs. 5.75 mm in a cylindrical hohlraum). Energy coupling improves in room temperature neopentane targets, as well as in hohlraums at higher gas fill density. In addition cross-beam energy transfer is being addressed directly by using targets that mock up one end of a hohlraum, but allow observation of the laser beam uniformity after energy transfer. Ideas such as splitting quads into “doublets” by re-pointing the right and left half of quads are also being pursued. LPI results of the Drive campaign will be summarized, and analyses of future directions presented.

  11. Dynamics of molecular clouds: observations, simulations, and NIF experiments

    NASA Astrophysics Data System (ADS)

    Kane, Jave O.; Martinez, David A.; Pound, Marc W.; Heeter, Robert F.; Casner, Alexis; Mancini, Roberto C.

    2015-02-01

    For over fifteen years astronomers at the University of Maryland and theorists and experimentalists at LLNL have investigated the origin and dynamics of the famous Pillars of the Eagle Nebula, and similar parsec-scale structures at the boundaries of HII regions in molecular hydrogen clouds. Eagle Nebula was selected as one of the National Ignition Facility (NIF) Science programs, and has been awarded four NIF shots to study the cometary model of pillar formation. These experiments require a long-duration drive, 30 ns or longer, to drive deeply nonlinear ablative hydrodynamics. The NIF shots will feature a new long-duration x-ray source prototyped at the Omega EP laser, in which multiple hohlraums are driven with UV light in series for 10 ns each and reradiate the energy as an extended x-ray pulse. The new source will be used to illuminate a science package with directional radiation mimicking a cluster of stars. The scaled Omega EP shots tested whether a multi-hohlraum concept is viable — whether earlier time hohlraums would degrade later time hohlraums by preheat or by ejecting ablated plumes that would deflect the later beams. The Omega EP shots illuminated three 2.8 mm long by 1.4 mm diameter Cu hohlraums for 10 ns each with 4.3 kJ per hohlraum. At NIF each hohlraum will be 4 mm long by 3 mm in diameter and will be driven with 80 kJ per hohlraum.

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

    SciTech Connect

    Glenzer, S H; MacGowan, B J; Michel, P; Meezan, N B; Suter, L J; Dixit, S N; Kline, J L; Kyrala, G A; Callahan, D A; Dewald, E L; Divol, L; Dzenitis, E; Edwards, J; Hamza, A V; Haynam, C A; Hinkel, D E; Kalantar, D H; Kilkenny, J D; Landen, O L; Lindle, J D; LePape, S; Moody, J D; Nikroo, A; Parham, T; Schneider, M B; Town, R J; Wegner, P; Widmann, K; Whitman, P; Young, B F; Van Wonterghem, B; Atherton, J E; Moses, E I

    2009-12-03

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

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

    PubMed

    Glenzer, S H; MacGowan, B J; Michel, P; Meezan, N B; Suter, L J; Dixit, S N; Kline, J L; Kyrala, G A; Bradley, D K; Callahan, D A; Dewald, E L; Divol, L; Dzenitis, E; Edwards, M J; Hamza, A V; Haynam, C A; Hinkel, D E; Kalantar, D H; Kilkenny, J D; Landen, O L; Lindl, J D; LePape, S; Moody, J D; Nikroo, A; Parham, T; Schneider, M B; Town, R P J; Wegner, P; Widmann, K; Whitman, P; Young, B K F; Van Wonterghem, B; Atherton, L J; Moses, E I

    2010-03-05

    Indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 megajoule. One hundred and ninety-two simultaneously fired laser beams heat ignition-emulate hohlraums to radiation temperatures of 3.3 million kelvin, compressing 1.8-millimeter-diameter capsules by the soft x-rays produced by the hohlraum. Self-generated plasma optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum, which produces a symmetric x-ray drive as inferred from the shape of the capsule self-emission. These experiments indicate that the conditions are suitable for compressing deuterium-tritium-filled capsules, with the goal of achieving burning fusion plasmas and energy gain in the laboratory.

  14. Science on NIF Eagle Nebula

    NASA Astrophysics Data System (ADS)

    Kane, Jave; Martinez, David; Pound, Marc; Heeter, Robert; Casner, Alexis; Villette, Bruno; Mancini, Roberto

    2014-10-01

    For over fifteen years astronomers at the University of Maryland and scientists at LLNL have investigated the origin and dynamics of the famous Pillars of the Eagle Nebula and similar parsec-scale structures at the boundaries of HII regions in molecular hydrogen clouds. Eagle Nebula is one of the National Ignition Facility (NIF) Science programs, and has been awarded two days of NIF shots to study the cometary model of pillar formation. The NIF shots will feature a new long-duration x-ray source prototyped at the Omega EP laser, in which multiple hohlraums mimicking a cluster of stars are driven with UV light in series for 10 ns each to create a 30 ns output x-ray pulse. The drive generates deeply nonlinear hydrodynamics in the Eagle science package, which consists of a dense layered plastic and foam core embedded in lower-density background foam. The scaled Omega EP shots validated the multi-hohlraum concept, showing that earlier time hohlraums do not degrade later time hohlraums by preheat or by ejecting ablated plumes that deflect the later beams. The Omega EP shots illuminated three 2.8 mm long by 1.4 mm diameter Cu hohlraums with 4.3 kJ per hohlraum. At NIF each hohlraum will be 4 mm long by 3 mm in diameter and will be driven with 80-100 kJ. Prepared by LLNL under Contract DE-AC52-07NA27344.

  15. Higher Velocity High-Foot Implosions on the National Ignition Facility Laser

    NASA Astrophysics Data System (ADS)

    Callahan, Debra

    2014-10-01

    After the end of the National Ignition Campaign on the National Ignition Facility (NIF) laser, we began a campaign to test capsule performance using a modified laser pulse-shape that delivers higher power early in the pulse (``high foot''). This pulse-shape trades one-dimensional performance (peak compression) for increased hydrodynamic stability. The focus of the experiments this year have been to improve performance by increasing the implosion velocity using higher laser power/energy, depleted uranium hohlraums, and thinner capsules. While the mix of ablator material into the hotspot has been low for all of these implosions, the challenge has been to keep the implosion shape under control. As the peak laser power is increased, the plasma density in the hohlraum is increased - making it more and more challenging for the inner cone beams to reach the midplane of the hohlraum and resulting in an oblate implosion. Depleted uranium hohlraums have higher albedo than Au hohlraums, which leads to additional drive and improved implosion shape. Thinner ablators increase the velocity by reducing the amount of payload; thinner ablators also put less mass into the hohlraum which results in improved inner beam propagation. These techniques have allowed us to push the capsule to higher and higher velocity. In parallel with this effort, we are exploring other hohlraums such as the rugby shaped hohlraum to allow us to push these implosions further. This talk will summarize the progress of the high foot campaign in terms of both capsule and hohlraum 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.

  16. Interpretation of symmetry experiments on Omega

    NASA Astrophysics Data System (ADS)

    Lours, Laurence; Bastian, Josiane; Monteil, Marie-Christine; Philippe, Franck; Jadaud, Jean-Paul

    2006-10-01

    The interpretation of the symmetry experiments performed on Omega in 2005 with 3 cone LMJ-like irradiation is presented here. The goal of this campaign was the characterization of the irradiation symmetry by X-ray imaging of the D2Ar capsule. Images of backlit implosion (as done in earlier campaigns with foam balls) and core emission were obtained on the same shot, and can be compared to FCI2 simulations. This set of shots comfirms former results with foam balls of a good symmetry control with 3 cones in empty hohlraums. The influence of the hohlraum shape on symmetry is also studied by comparison of cylindrical hohlraums vs rugby ones.

  17. The Early Years of Indirect Drive Development for High Energy Density Physics Experiments at AWE

    NASA Astrophysics Data System (ADS)

    Thomas, Brian

    2016-10-01

    The importance of laser driven indirect drive for high energy density physics experiments was recognised at A WE in 1971. The two beam 1TW HELEN laser was procured to work in this area and experiments with this system began in 1980. Early experiments in hohlraum coupling and performance scaling with both l.06μm and 0.53μm will be described together with experiments specifically designed to confirm the understanding of radiation wave propagation, hohlraum heating and hohlraum plasma filling. The use of indirect drive for early experiments to study spherical and cylindrical implosions, opacity, EOS, mix and planar radiation hydrodynamics experiments will also be described.

  18. Design Calculations For NIF Convergent Ablator Experiments

    SciTech Connect

    Olson, R E; Hicks, D G; Meezan, N B; Callahan, D A; Landen, O L; Jones, O S; Langer, S H; Kline, J L; Wilson, D C; Rinderknecht, H; Zylstra, A; Petrasso, R D

    2011-10-25

    The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash rhor, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.

  19. Progress of LMJ-relevant implosions experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Philippe, F.; Tassin, V.; Seytor, P.; Monteil, M.-C.; Gauthier, P.; Park, H. S.; Robey, H.; Ross, J.; Amendt, P.; Girard, F.; Villette, B.; Reverdin, C.; Loiseau, P.; Caillaud, T.; Landoas, O.; Li, C. K.; Petrasso, R.; Seguin, F.; Rosenberg, M.; Renaudin, P.

    2013-11-01

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

  20. An assessment of the 3D geometric surrogacy of shock timing diagnostic techniques for tuning experiments on the NIF

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Munro, D. H.; Spears, B. K.; Marinak, M. M.; Jones, O. S.; Patel, M. V.; Haan, S. W.; Salmonson, J. D.; Landen, O. L.; Boehly, T. R.; Nikroo, A.

    2008-05-01

    Ignition capsule implosions planned for the National Ignition Facility (NIF) require a pulse shape with a carefully designed series of four steps, which launch a corresponding series of shocks through the ablator and DT ice shell. The relative timing of these shocks is critical for maintaining the DT fuel on a low adiabat. The current NIF specification requires that the timing of all four shocks be tuned to an accuracy of <= +/- 100ps. To meet these stringent requirements, dedicated tuning experiments are being planned to measure and adjust the shock timing on NIF. These tuning experiments will be performed in a modified hohlraum geometry, where a re-entrant Au cone is added to the standard NIF hohlraum to provide optical diagnostic (VISAR and SOP) access to the shocks as they break out of the ablator. This modified geometry is referred to as the 'keyhole' hohlraum and introduces a geometric difference between these tuning-experiments and the full ignition geometry. In order to assess the surrogacy of this modified geometry, 3D simulations using HYDRA [1] have been performed. The results from simulations of a quarter of the target geometry are presented. Comparisons of the hohlraum drive conditions and the resulting effect on the shock timing in the keyhole hohlraum are compared with the corresponding results for the standard ignition hohlraum.

  1. First beryllium capsule implosions on the National Ignition Facility

    SciTech Connect

    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.

  2. First beryllium capsule implosions on the National Ignition Facility

    SciTech Connect

    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.; and others

    2016-05-15

    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.

  3. Capsule Design for Hybrid Shock Ignition

    NASA Astrophysics Data System (ADS)

    Baumgaertel, J. A.; Dodd, E. S.; Loomis, E. N.

    2014-10-01

    Hybrid Shock-Ignition (HSI) is an alternate fusion energy concept that combines indirect drive and shock ignition schemes in order to access new regimes in National Ignition Facility (NIF) hohlraum physics. Building off of tetrahedral hohlraum experiments at the OMEGA laser facility, we have preliminary designs for spherical hohlraums that combine symmetrically arranged laser entrance holes for indirect-drive beams (to initially compress the capsule) and holes for direct-drive beams to drive a strong ignitor shock (to further compress and ignite the fuel). A LANL Eulerian hydrodynamic code is being used to find optimal laser drive, hohlraum, and capsule specifications, via criteria such as implosion symmetry, implosion time, and neutron yield. At first, drive will be modeled using a radiation source to mimic the hohlraum drive, and later, ignitor beams will be added. Initial capsule designs will be presented for experiments to develop the HSI platform on the sub-ignition scale OMEGA laser facility in FY15. Supported under the U.S. Department of Energy by the Los Alamos National Security, LLC under Contract DE-AC52-06NA25396. LA-UR-14-25071.

  4. Metrics for comparing drive on the capsule for indirect drive implosions on NIF

    NASA Astrophysics Data System (ADS)

    Callahan, Debra; Hurricane, Omar; Moody, John; Berzak Hopkins, Laura; Divol, Laurent; Doeppner, Tilo; Dewald, Eduard; Hinkel, Denise; Khan, Shahab; Kritcher, Andrea; Lepape, Sebastien; Ma, Tammy; Meezan, Nathan; Ralph, Joseph; Ross, Steven

    2016-10-01

    Radiation drive on the capsule is an important parameter in ICF because it determines the implosion velocity. For indirect drive, the effective capsule drive is a combination of hohlraum and capsule physics. The hohlraum converts the laser energy into xrays - both flux and spectrum. The xray drive is a function of the hohlraum size, material, and hohlraum fill in addition to being a function of the laser power and energy. The timing of the drive with respect to the capsule implosion trajectory plays a role in the way in the way the capsule absorbs the energy as does the choice of ablator material and capsule dopant. In this presentation, we will look at trends in the data from both hohlraum (Dante, SXI) and capsule diagnostics (bangtime, capsule xray yield) as a method for comparing the drive on the capsule for a variety of designs. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  5. High-density carbon ablator experiments on the National Ignition Facilitya)

    SciTech Connect

    MacKinnon, A. J.; Meezan, N. B.; Ross, J. S.; Le Pape, S.; Berzak Hopkins, L.; Divol, L.; Ho, D.; Milovich, J.; Pak, A.; Ralph, J.; Döppner, T.; Patel, P. K.; Thomas, C.; Tommasini, R.; Haan, S.; MacPhee, A. G.; McNaney, J.; Caggiano, J.; Hatarik, R.; Bionta, R.; Ma, T.; Spears, B.; Rygg, J. R.; Benedetti, L. R.; Town, R. P. J.; Bradley, D. K.; Dewald, E. L.; Fittinghoff, D.; Jones, O. S.; Robey, H. R.; Moody, J. D.; Khan, S.; Callahan, D. A.; Hamza, A.; Biener, J.; Celliers, P. M.; Braun, D. G.; Erskine, D. J.; Prisbrey, S. T.; Wallace, R. J.; Kozioziemski, B.; Dylla-Spears, R.; Sater, J.; Collins, G.; Storm, E.; Hsing, W.; Landen, O.; Atherton, J. L.; Lindl, J. D.; Edwards, M. J.; Frenje, J. A.; Gatu-Johnson, M.; Li, C. K.; Petrasso, R.; Rinderknecht, H.; Rosenberg, M.; Séguin, F. H.; Zylstra, A.; Knauer, J. P.; Grim, G.; Guler, N.; Merrill, F.; Olson, R.; Kyrala, G. A.; Kilkenny, J. D.; Nikroo, A.; Moreno, K.; Hoover, D. E.; Wild, C.; Werner, E.

    2014-05-01

    High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has a higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results in a thinner ablator with a larger inner radius for a given capsule scale. This leads to higher x-ray absorption and shorter laser pulses compared to equivalent CH designs. This paper will describe a series of experiments carried out to examine the feasibility of using HDC as an ablator using both gas filled hohlraums and lower density, near vacuum hohlraums. These experiments have shown that deuterium (DD) and deuterium-tritium gas filled HDC capsules driven by a hohlraum filled with 1.2 mg/cc He gas, produce neutron yields a factor of 2× higher than equivalent CH implosions, representing better than 50% Yield-over-Clean (YoC). In a near vacuum hohlraum (He = 0.03 mg/cc) with 98% laser-to-hohlraum coupling, such a DD gas-filled capsule performed near 1D expectations. A cryogenic layered implosion version was consistent with a fuel velocity = 410 ± 20 km/s with no observed ablator mixing into the hot spot.

  6. Pulsed Magnetic Field System for Magnetized Target Experiments at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Rhodes, M. A.; Solberg, J. M.; Logan, B. G.; Perkins, L. J.

    2014-10-01

    High-magnitude magnetic fields applied to inertially confined targets may improve fusion yield and enable basic science applications. We discuss the development of a pulsed magnetic field system for NIF with the goal of applying 10--70 T to various NIF targets. While the driver may be little more than a spark-gap switched capacitor, numerous complex challenges exist in fielding such a system on NIF. The coil surrounding the metallic hohlraum drives induced current in the hohlraum wall. Both the coil and hohlraum wall must survive ohmic heating and J × B forces for several microseconds. Pulsed power must couple to the coil in the NIF environment. The system must not cause late-time optics damage due to debris. There is very limited volume for the driver in a NIF Diagnostic Instrument Manipulator (DIM). We are modeling the coil and hohlraum MHD effects with the LLNL code, ALE3D. However, the simulations lack complete and accurate data for all the required thermo-physical material properties over the expected range of temperatures (below vaporization) and pressures. Therefore, substantial experimental development is planned in the coming year. We present coil and hohlraum simulations results, overall system design, and progress towards an operational prototype test-stand. LLNL is operated by LLNS, LLC, for the U.S. D.O.E., NNSA under Contract DE-AC52-07NA27344. This work was supported by LLNL LDRD 14-ER-028.

  7. High-density carbon ablator experiments on the National Ignition Facility

    SciTech Connect

    MacKinnon, A. J. Meezan, N. B.; Ross, J. S.; Le Pape, S.; Berzak Hopkins, L.; Divol, L.; Ho, D.; Milovich, J.; Pak, A.; Ralph, J.; Döppner, T.; Patel, P. K.; Thomas, C.; Tommasini, R.; Haan, S.; MacPhee, A. G.; McNaney, J.; Caggiano, J.; Hatarik, R.; Bionta, R.; and others

    2014-05-15

    High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has a higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results in a thinner ablator with a larger inner radius for a given capsule scale. This leads to higher x-ray absorption and shorter laser pulses compared to equivalent CH designs. This paper will describe a series of experiments carried out to examine the feasibility of using HDC as an ablator using both gas filled hohlraums and lower density, near vacuum hohlraums. These experiments have shown that deuterium (DD) and deuterium-tritium gas filled HDC capsules driven by a hohlraum filled with 1.2 mg/cc He gas, produce neutron yields a factor of 2× higher than equivalent CH implosions, representing better than 50% Yield-over-Clean (YoC). In a near vacuum hohlraum (He = 0.03 mg/cc) with 98% laser-to-hohlraum coupling, such a DD gas-filled capsule performed near 1D expectations. A cryogenic layered implosion version was consistent with a fuel velocity = 410 ± 20 km/s with no observed ablator mixing into the hot spot.

  8. Analysis of stimulated Raman backscatter and stimulated Brillouin backscatter in experiments performed on SG-III prototype facility with a spectral analysis code

    SciTech Connect

    Hao, Liang; Zhao, Yiqing; Hu, Xiaoyan; Zou, Shiyang; Yang, Dong; Wang, Feng; Peng, Xiaoshi; Li, Zhichao; Li, Sanwei; Xu, Tao; Wei, Huiyue; Liu, Zhanjun; Zheng, Chunyang

    2014-07-15

    Experiments about the observations of stimulated Raman backscatter (SRS) and stimulated Brillouin backscatter (SBS) in Hohlraum were performed on Shenguang-III (SG-III) prototype facility for the first time in 2011. In this paper, relevant experimental results are analyzed for the first time with a one-dimension spectral analysis code, which is developed to study the coexistent process of SRS and SBS in Hohlraum plasma condition. Spectral features of the backscattered light are discussed with different plasma parameters. In the case of empty Hohlraum experiments, simulation results indicate that SBS, which grows fast at the energy deposition region near the Hohlraum wall, is the dominant instability process. The time resolved spectra of SRS and SBS are numerically obtained, which agree with the experimental observations. For the gas-filled Hohlraum experiments, simulation results show that SBS grows fastest in Au plasma and amplifies convectively in C{sub 5}H{sub 12} gas, whereas SRS mainly grows in the high density region of the C{sub 5}H{sub 12} gas. Gain spectra and the spectra of backscattered light are simulated along the ray path, which clearly show the location where the intensity of scattered light with a certain wavelength increases. This work is helpful to comprehend the observed spectral features of SRS and SBS. The experiments and relevant analysis provide references for the ignition target design in future.

  9. Observation of indirect-drive inertial confinement fusion implosion asymmetry on the Shenguang III prototype laser facility

    NASA Astrophysics Data System (ADS)

    Li, Hang

    2016-10-01

    Three kinds of hohlraum lengths were used to study the symmetry scaling on the Shenguang III prototype laser facility. Hot spot radiography was taken by an x-ray framing camera and the hot spot ellipticity a/b which showd a ``P2 like'' implosion distortion was measured. The indirect-drive implosion asymmetry is determined by the hohlraum radiation uniformity. Most factors affecting hohlraum radiation uniformity can be taken into account by a view-factor code IRAD 3D, so time-resolved difference between polar and equatorial radiation flux can by calculated by IRAD 3D. Then, the time-resolved a/b evolution can be calculated by a simplified analytic model integrating the total difference between polar and equatorial radiation flux before each moment, because during the acceleration phase the capsule distortion at some time is the accumulation effect of total radiation drive before that time. The calculated results of the time-resolved implosion asymmetry are basically in agreement with experimental results. Meanwhile, the physical mechanism for how hohlraum radiation nonuniformity evolution induces the variations of implosion asymmetry with hohlraum length and time is analyzed.

  10. Deep Dive Topic: Choosing between ablators

    SciTech Connect

    Hurricane, O. A.; Thomas, C.; Olson, R.

    2015-07-14

    Recent data on implosions using identical hohlraums and very similar laser drives underscores the conundrum of making a clear choice of one ablator over another. Table I shows a comparison of Be and CH in a nominal length, gold, 575 μm-diameter, 1.6 mg/cc He gas-fill hohlraum while Table II shows a comparison of undoped HDC and CH in a +700 length, gold, 575 μm diameter, 1.6 mg/cc He gas fill hohlraum. As can be seen in the tables, the net integrated fusion performance of these ablators is the same to within error bars. In the case of the undoped HDC and CH ablators, the hot spot shapes of the implosions were nearly indistinguishable for the experiments listed in Table II.

  11. Experimental Program to Elucidate and Control Stimulated Brillouin and Raman Backscattering in Long-Scale Plasmas

    SciTech Connect

    Fernandez, J.C.; Cobble, J.A.; Montgomery, D.S.; Wilke, M.D.

    1998-10-19

    Laser-plasma instability is a serious concern for indirect-drive inertial confinement fusion (ICF), where laser beams illuminate the interior of a cavity (called a hohlraum) to produce X-rays to drive the implosion of a fusion capsule. Stimulated Raman and Brillouin backscattering (SRS and SBS) could result in unacceptably high laser reflectivities. Unfortunately, it is impossible at present to fully simulate these processes realistically. The authors experimental program aims to understand these instabilities by pursuing a dual strategy. (1) They use a gas-filled hohlraum design, which best approaches ignition-hohlraum conditions, on the Nova laser to identify important non linear trends. (2) They are shifting towards more fundamental experiments with a nearly diffraction-limited interaction laser beam illuminating extremely well characterized plasmas on the Trident laser facility at Los Alamos to probe the relevant fundamental processes.

  12. Capsule performance optimization in the National Ignition Campaigna)

    NASA Astrophysics Data System (ADS)

    Landen, O. L.; Boehly, T. R.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Hoffman, N.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Kyrala, G. A.; Michel, P.; Milovich, J.; Munro, D. H.; Nikroo, A.; Olson, R. E.; Robey, H. F.; Spears, B. K.; Thomas, C. A.; Weber, S. V.; Wilson, D. C.; Marinak, M. M.; Suter, L. J.; Hammel, B. A.; Meyerhofer, D. D.; Atherton, J.; Edwards, J.; Haan, S. W.; Lindl, J. D.; MacGowan, B. J.; Moses, E. I.

    2010-05-01

    A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

  13. Capsule performance optimization in the National Ignition Campaign

    SciTech Connect

    Landen, O. L.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Michel, P.; Milovich, J.; Munro, D. H.; Robey, H. F.; Spears, B. K.; Thomas, C. A.

    2010-05-15

    A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

  14. ICF Ablator Physics Experiments on Saturn and Nova

    NASA Astrophysics Data System (ADS)

    Olson, Rick

    1996-11-01

    In indirect drive ICF, the driver energy is absorbed in a high-Z enclosure (or "hohlraum") that surrounds a spherical shell (or "capsule") containing DT fuel. The hohlraum walls are heated by the driver and emit x-rays, which are absorbed by the capsule material (the "ablator") and drive the implosion. We have used the Saturn z-pinch at SNL and the Nova laser at LLNL to explore the behavior of ablator material in x-ray radiation environments comparable in magnitude, spectrum and duration to those that will be experienced in National Ignition Facility (NIF) hohlraums. The large x-ray outputs available from pulsed-power driven z-pinches have enabled us to drive hohlraums of full NIF ignition scale size at radiation temperatures and timescales comparable to those required for the low power "foot" pulse of an ignition capsule. The high intensity of the Nova laser has allowed us to study capsule ablator physics in smaller scale hohlraums at radiation temperatures and timescales relevant to the peak power pulse for an ignition capsule. Taken together, these experiments have allowed us test our radiation-hydrodynamics computer code predictions of ablator opacity, radiation flow, and equation of state over almost the complete range of radiation environments to be encountered in a NIF hohlraum. * in collaboration with J. Porter, G. Chandler, D. Fehl, D. Jobe, R. Leeper, K. Matzen, J. McGurn, D. Noack, L. Ruggles, P. Sawyer, J. Torres, M. Vargas, D. Zagar (SNL), and H. Kornblum, T. Orzechowski, L. Suter, R. Thiessen, R. Wallace (LLNL), and the Saturn and Nova operations and diagnostic crews at SNL and LLNL. +This work was supported by the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  15. Integrated ignition calculations for indirectly driven targets

    NASA Astrophysics Data System (ADS)

    Krauser, William J.; Wilde, Bernhard H.; Wilson, Douglas C.; Bradley, Paul; Swenson, Fritz

    1996-05-01

    We present two-dimensional LASNEX calculations of the hohlraum and ignition capsules proposed for the National Ignition Facility (NIF). Our current hohlraum design is a 2.76 mm radius, 9.49 mm long gold cylinder with 1.39 mm radius laser entrance holes (LEH) which are covered by 1 μm thick polyamide foils. Laser beams with less than 1.4 MJ total energy and less than 400 TW peak power irradiate the cylinder wall from two separate cones entering each LEH. The hohlraum interior is filled with hydrogen-helium gas (50-50 atomic) at a density of 0.83 mg/cm3 to suppress the inward expansion of the wall. The capsule uses either a 160 μm plastic ablator doped with bromine (the baseline design), or a 155 μm beryllium ablator doped with copper (the beryllium design). The ablator surrounds an 80 μm thick deuterium-tritium (DT) ice layer with an inner radius of 0.87 mm. We will show the results of integrated, two-dimensional calculations of the hohlraum and the capsule. Plasma conditions within the hohlraum will be described. Peak radiation temperatures in the hohlraum are about 300 eV. These calculations proceed through the implosion, ignition, and burn of the DT capsule. Current peak calculated yields are 12 MJ for the baseline design and 6.9 MJ for the capsule with the beryllium ablator, although higher yields should be achievable with improved ``tuning'' of the laser power levels.

  16. LLNL ICF highlights for the period of July 14, 2016 to July 20, 2016

    SciTech Connect

    Herrmann, M. C.

    2016-07-25

    LLNL executed two HED Fused Silica Dome experiments as part of the complex hydrodynamics campaign on NIF. These shots assessed breakout times and velocities of shocks at five different angles separated by 45°. Each target looked at three different locations on the capsule measuring the shock breakout time and speed. The experiments used a significantly larger hohlraum and energy in the laser pulse than in previous complex hydrodynamics hohlraums. LLNL conducted a shot on NIF to continue developing a high pressure drive platform for Rayleigh-Taylor strength experiments. VISAR was the primary diagnostic and returned good quality data.

  17. Inline CBET Model Including SRS Backscatter

    SciTech Connect

    Bailey, David S.

    2015-06-26

    Cross-beam energy transfer (CBET) has been used as a tool on the National Ignition Facility (NIF) since the first energetics experiments in 2009 to control the energy deposition in ignition hohlraums and tune the implosion symmetry. As large amounts of power are transferred between laser beams at the entrance holes of NIF hohlraums, the presence of many overlapping beat waves can lead to stochastic ion heating in the regions where laser beams overlap [P. Michel et al., Phys. Rev. Lett. 109, 195004 (2012)]. Using the CBET gains derived in this paper, we show how to implement these equations in a ray-based laser source for a rad-hydro code.

  18. 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.

  19. Indirect-drive inertial confinement fusion using highly supersonic, radiatively cooled, plasma slugs.

    PubMed

    Chittenden, J P; Dunne, M; Zepf, M; Lebedev, S V; Ciardi, A; Bland, S N

    2002-06-10

    We present a new approach to indirect-drive inertial confinement fusion which makes use of highly supersonic, radiatively cooled, slugs of plasma to energize a hohlraum. 2D resistive magnetohydrodynamic simulations of slug formation in shaped liner Z-pinch implosions are presented along with 2D-radiation-hydrodynamic simulations of the slug impacting a converter foil and 3D-view-factor simulations of a double-ended hohlraum. Results for the Z facility at Sandia National Laboratory indicate that two synchronous slugs of 250 kJ kinetic energy could be produced, resulting in a capsule surface temperature of approximately 225 eV.

  20. Shock Timing experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Celliers, P. M.; Boehly, T. R.; Robey, H. F.; Datte, P. S.; Bowers, M. W.; Krauter, K. G.; Frieders, G.; Ross, G. F.; Jackson, J. L.; Olson, R. E.; Munro, D. H.; Nikroo, A.; Kroll, J. J.; Horner, J. B.; Hamza, A. V.; Bhandarkar, S. D.; Gibson, C. R.; Eggert, J. H.; Smith, R. F.; Park, H.-S.; Young, B. K.; Hsing, W. W.; Collins, G. W.; Landen, O. L.; Meyerhofer, D. D.

    2011-06-01

    Experiments are proceeding to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility. These experiments use a modified cryogenic hohlraum geometry designed to match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with VISAR (Velocity Interferometer System for Any Reflector). The results of these measurements will be used to set the pulse shape for ignition capsule implosions to follow. Prepared by LLNL under Contract DE-AC52-07NA27344.

  1. Experimental Studies of Convection Effects in a Cryogenic NIF Ignition Target

    SciTech Connect

    Moody, J D; Sanchez, J J; Bittner, D N; Giedt, W H; London, R L; Sater, J D; Burmann, J A; Jones, R L

    2003-08-22

    We describe experiments which investigate convection effects on hydrogen ice layers in a transparent CH capsule suspended with a fill-tube. These experiments validate simulations which show that unmitigated convection from the hohlraum fill gas can produce significant distortions to the cryogenic hydrogen ice layer. Experimental results show good agreement with thermal simulations which include conduction and convection.

  2. Inertial confinement fusion quarterly report, July--September 1994. Volume 4, Number 4

    SciTech Connect

    Honea, E.

    1994-09-01

    The ICF Quarterly continues with six articles in this issue describing recent developments in the Inertial Confinement Fusion (ICF) Program at Lawrence Livermore National Laboratory. The topics include plasma characterization, production of millimeter scale-length plasmas for studying laser-plasma instabilities, hohlraum physics, three-dimensional hydrodynamic modeling, crystal growth, and laser-beam smoothing.

  3. Thomson scattering from laser plasmas

    SciTech Connect

    Moody, J D; Alley, W E; De Groot, J S; Estabrook, K G; Glenzer, S H; Hammer, J H; Jadaud, J P; MacGowan, B J; Rozmus, W; Suter, L J; Williams, E A

    1999-01-12

    Thomson scattering has recently been introduced as a fundamental diagnostic of plasma conditions and basic physical processes in dense, inertial confinement fusion plasmas. Experiments at the Nova laser facility [E. M. Campbell et al., Laser Part. Beams 9, 209 (1991)] have demonstrated accurate temporally and spatially resolved characterization of densities, electron temperatures, and average ionization levels by simultaneously observing Thomson scattered light from ion acoustic and electron plasma (Langmuir) fluctuations. In addition, observations of fast and slow ion acous- tic waves in two-ion species plasmas have also allowed an independent measurement of the ion temperature. These results have motivated the application of Thomson scattering in closed-geometry inertial confinement fusion hohlraums to benchmark integrated radiation-hydrodynamic modeling of fusion plasmas. For this purpose a high energy 4{omega} probe laser was implemented recently allowing ultraviolet Thomson scattering at various locations in high-density gas-filled hohlraum plasmas. In partic- ular, the observation of steep electron temperature gradients indicates that electron thermal transport is inhibited in these gas-filled hohlraums. Hydrodynamic calcula- tions which include an exact treatment of large-scale magnetic fields are in agreement with these findings. Moreover, the Thomson scattering data clearly indicate axial stagnation in these hohlraums by showing a fast rise of the ion temperature. Its timing is in good agreement with calculations indicating that the stagnating plasma will not deteriorate the implosion of the fusion capsules in ignition experiments.

  4. Fabrication and testing of gas-filled targets for large-scale plasma experiments on nova

    SciTech Connect

    Stone, G.F.; Rivers, C.J.; Spragge, M.R.; Wallace, R.J.

    1996-06-01

    The proposed next-generation ICF facility, the National Ignition Facility (NIF) is designed to produce energy gain from x-ray heated {open_quotes}indirect-drive{close_quotes} fuel capsules. For indirect-drive targets, laser light heats the inside of the Au hohlraum wall and produces x rays which in turn heat and implode the capsule to produce fusion conditions in the fuel. Unlike Nova targets, in NIF-scale targets laser light will propagate through several millimeters of gas, producing a plasma, before impinging upon the Au hohlraum wall. The purpose of the gas-produced plasma is to provide sufficient pressure to keep the radiating Au surface from expanding excessively into the hohlraum cavity. Excessive expansion of the Au wall interacts with the laser pulse and degrades the drive symmetry of the capsule implosion. The authors have begun an experimental campaign on the Nova laser to study the effect of hohlraum gas on both laser-plasma interaction and implosion symmetry. In their current NIF target design, the calculated plasma electron temperature is T{sub e} {approx} 3 keV and the electron density is N{sub e} {approx} 10{sup 21}cm{sup {minus}3}.

  5. Symmetry tuning for ignition capsules via the symcap technique

    SciTech Connect

    Kyrala, G. A.; Kline, J. L.; Dixit, S.; Glenzer, S.; Kalantar, D.; Bradley, D.; Izumi, N.; Meezan, N.; Landen, O.; Callahan, D.; Weber, S. V.; Holder, J. P.; Glenn, S.; Edwards, M. J.; Koch, J.; Suter, L. J.; Haan, S. W.; Town, R. P. J.; Michel, P.; Jones, O.

    2011-05-15

    Symmetry of an implosion is crucial to get ignition successfully. Several methods of control and measurement of symmetry have been applied on many laser systems with mm size hohlraums and ns pulses. On the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] we have large hohlraums of cm scale, long drive pulses of 10 s of ns, and a large number of beams with the option to tune their wavelengths. Here we discuss how we used the x-ray self-emission from imploding surrogates to ignition capsules (symcaps) to measure the symmetry of the implosion. We show that symcaps are good surrogates for low order symmetry, though having lower sensitivity to distortions than ignition capsules. We demonstrate the ability to transfer energy between laser beams in a gas-filled hohlraum using wavelength tuning, successfully tuning the lowest order symmetry of the symcaps in different size hohlraums at different laser energies within the specification established by calculations for successful ignition.

  6. Inertial confinement fusion quarterly report, October-December 1996

    SciTech Connect

    Hammer, J.

    1997-01-01

    The articles in this issue report progress on: Supernova Hydrodynamics Experiments on the Nova Laser; Characterization of Laser-Driven Shock Waves Using Interferometry; Absolute Equation of State Measurements of Compressed Liquid Deuterium Using Nova; Low-Density-Foam Shells; Tetrahedral Hohlraums; The Rosseland Mean Opacity of a Composite Material at High Temperatures.

  7. First shock tuning and backscatter measurements for large case-to-capsule ratio beryllium targets

    NASA Astrophysics Data System (ADS)

    Loomis, Eric; Yi, Austin; Kline, John; Kyrala, George; Simakov, Andrei; Wilson, Doug; Ralph, Joe; Dewald, Eduard; Strozzi, David; Celliers, Peter; Millot, Marius; Tommasini, Riccardo

    2016-10-01

    The current under performance of target implosions on the National Ignition Facility (NIF) has necessitated scaling back from high convergence ratio to access regimes of reduced physics uncertainties. These regimes, we expect, are more predictable by existing radiation hydrodynamics codes giving us a better starting point for isolating key physics questions. One key question is the lack of predictable in-flight and hot spot shape due to a complex hohlraum radiation environment. To achieve more predictable, shape tunable implosions we have designed and fielded a large 4.2 case-to-capsule ratio (CCR) target at the NIF using 6.72 mm diameter Au hohlraums and 1.6 mm diameter Cu-doped Be capsules. Simulations show that at these dimensions during a 10 ns 3-shock laser pulse reaching 270 eV hohlraum temperatures, the interaction between hohlraum and capsule plasma, which at lower CCR lead to beam propagation impedance by artificial plasma stagnation, are reduced. In this talk we will present measurements of early time drive symmetry using two-axis line-imaging velocimetry (VISAR) and streaked radiography measuring velocity of the imploding shell and their comparisons to post-shot calculations using the code HYDRA (Lawrence Livermore National Laboratory).

  8. Measurements of Hard X-Ray Emission Suggest Absorption Along the Path of the Inner Beams in High Foot Implosion Experiments on the NIF

    NASA Astrophysics Data System (ADS)

    Ralph, Joseph; Pak, Arthur; Otto, Landen; Kritcher, Andrea; Ma, Tammy; Charles, Jarrott; Callahan, Debra; Hinkel, Denise; Berzak Hopkins, Laura; Moody, John; Khan, Shahab; Doeppner, Tilo; Rygg, Ryan; Hurricane, Omar

    2016-10-01

    The current high foot hohlraum design fielded on the National Ignition Facility is aimed at providing uniform x-ray drive to provide a spherical implosion by lowering the gas fill from 1.6 to 0.6 mg/cc and increasing the hohlraum width from 5.75 to 6.72 mm while maintaining the same 1.8 mm capsule diameter from previous designs. These changes are intended to improve beam propagation without the need for crossed beam energy transfer. Analysis of the measurements of hard x-ray emission from the gated x-ray detector (GXD) and the static x-ray imager (SXI) looking through the laser entrance hole indicate a significant fraction of the inner beam incident energy is absorbed in the high z blow-off region (either uranium or gold) before reaching the inner wall near the equator. Comparison of inner beam absorption in this region and its effect on the implosion symmetry measurements will be presented. Additionally, the sensitivity of this absorption feature and therefore the implosion symmetry to the pulse shape, hohlraum fill pressure and fraction of energy in beams depositing energy at the hohlraum equator will be discussed. 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. LMJ Target design with the A1040 CH-ignition capsule in a cocktail holraum

    NASA Astrophysics Data System (ADS)

    Malinie, G.; Boniface, C.

    2008-11-01

    The A1040 indirect-drive ignition capsule was originally designed for the ``Full LMJ'' 240-beam configuration. An ``Ignition milestone'' has been scheduled, when the LMJ will be only partly completed, with a 160-beam, 2-cone configuration. A first approach to meet this milestone is to scale down the capsule and hohlraum of the full LMJ design. Here we use a different approach and show the A1040 ``as is'' can still meet the milestone, provided that a suitable cocktail-walled rugby hohlraum is used to drive the capsule. This is because this kind of hohlraum has a better energetic efficiency than the gold-walled cylinder originally used. From 1D and 2D integrated simulations, we investigate the influence of various parameters of the design, such as the shape of the four steps of the laser pulse, the density of the H/He gas filling of the hohlraum, and the effect of a thin gold coating on the outer surface of the polyimid window used to contain the gas.

  10. Laser-plasma interactions in NIF-scale plasmas (HLP5 and HLP6)

    SciTech Connect

    MacGowan, B.; Berger, R.; Fernandez, J.

    1996-06-01

    The understanding of laser-plasma interactions in ignition-scale inertial confinement fusion (ICF) hohlraum targets is important for the success of the proposed National Ignition Facility (NIF). The success of an indirect-drive ICF ignition experiment depends on the ability to predict and control the history and spatial distribution of the x-radiation produced by the laser beams that are absorbed by the inside of the hohlraum wall. Only by controlling the symmetry of this x-ray drive is it possible to obtain the implosion symmetry in the fusion pellet necessary for ignition. The larger hohlraums and longer time scales required for ignition-scale targets result in the presence of several millimeters of plasma (electron density n{sub e} {approximately} 0.1 n{sub c} {approximately} 10{sup 21} cm{sup {minus}3}), through which the 3{omega} (351-nm) laser beams must propagate before they are absorbed at the hohlraum wall. Hydrodynamic simulations show this plasma to be very uniform [density-gradient scalelength L{sub n} = n{sub e}(dn{sub e}/dx){sup {minus}1}{approximately} 2mm] and to exhibit low velocity gradients [velocity-gradient scale-length L{sub v} = c{sub s}(dv/dx){sup {minus}1} > 6 mm].

  11. Update on indirect drive ignitin target design for NIF

    SciTech Connect

    Haan, S W; Amendt, P A; Dittrich, T R; Hammel, B A; Hatchett, S P; Herrmann, M C; Hurricane, O A; Jones, O S; Lindl, J D; Marinak, M M; Munro, D; Pollaine, S M; Salmonson, J D; Strobel, G A; Suter, L J

    2003-10-21

    Recent ignition target design effort has emphasized systematic exploration of the parameter space of possible ignition targets, providing as specific as possible comparisons between the various targets. This is to provide guidance for target fabrication R&D, and for the other elements of the ignition program. Targets are being considered that span 250-300 eV drive temperatures, capsule energies from 150 to 600 kJ, cocktail and gold hohlraum spectra, and three ablator materials (Be[Cu], CH[Ge], and polyimide). Capsules with graded doped beryllium ablators are being found to be very stable with respect to short-wavelength Rayleigh-Taylor growth. Sensitivity to ablator roughness, ice roughness, and asymmetry is being explored, as it depends on ablator material, drive temperature, and absorbed energy. Special features being simulated include fill holes, fill tubes, and capsule support tents. Three-dimensional simulations are being used to ensure adequate radiation symmetry in 3D, and to ensure that coupling of 3D asymmetry and 3D Rayleigh-Taylor does not adversely affect planned performance. Integrated 3D hohlraum simulations indicate that 3D features in the laser illumination pattern affect the hohlraums' performance, and the hohlraum is being redesigned to accommodate these effects.

  12. Final Report: Development of X-ray tracer diagnostics for radiatively-driven ablator experiments, November 1, 1997 - October 31, 1998

    SciTech Connect

    MacFarlane, J.J.; Cohen, D.H.; Ping Wang, G.A.; Moses, R.R.; Peterson, P.A.; Jaanimagi; Landen, O.L.; Olson, R.E.; Murphy, T.J.; Magelssen, G.R.; Delamater, N.D.

    1999-06-01

    This is a combined experimental and theoretical analysis of tracer layers as spectral diagnostics for radiation burn-through of ablator materials. German-doped plastic is attached as a witness plate to a laser driven hohlraum. Backlit absorption spectroscopy is used as a diagnostic. Target shots were performed on the OMEGSA laser at UR/LLE.

  13. Advances in NIF Shock Timing Experiments

    NASA Astrophysics Data System (ADS)

    Robey, Harry

    2012-10-01

    Experiments are underway to tune the shock timing of capsule implosions on the National Ignition Facility (NIF). These experiments use a modified cryogenic hohlraum geometry designed to precisely match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to multiple shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of all four shocks is diagnosed with VISAR (Velocity Interferometer System for Any Reflector). Experiments are now routinely conducted in a mirrored keyhole geometry, which allows for simultaneous diagnosis of the shock timing at both the hohlraum pole and equator. Further modifications are being made to improve the surrogacy to ignition hohlraums by replacing the standard liquid deuterium (D2) capsule fill with a deuterium-tritium (DT) ice layer. These experiments will remove any possible surrogacy difference between D2 and DT as well as incorporate the physics of shock release from the ice layer, which is absent in current experiments. Experimental results and comparisons with numerical simulation are presented.

  14. Time dependent view factor methods

    SciTech Connect

    Kirkpatrick, R.C.

    1998-03-01

    View factors have been used for treating radiation transport between opaque surfaces bounding a transparent medium for several decades. However, in recent years they have been applied to problems involving intense bursts of radiation in enclosed volumes such as in the laser fusion hohlraums. In these problems, several aspects require treatment of time dependence.

  15. Serum lipoproteins of patients with glycogen storage disease.

    PubMed

    Rosenfeld, E L; Chibisov, I V; Karmansky, I M; Tabolin, V A; Chistova, L V; Leontiev, A F

    1980-03-14

    Seventeen patients with different types of glycogen storage disease (GSD) were under observation. The type of the disease was defined from glucaemic and lactotaemic curves obtained in glucose, galactose and adrenaline tolerance tests and by biochemical analysis of liver biopsy specimens. Seven patients were found to have Type I; five patients, Type III; one patient, Type VI; and four patients, the Type IX (or X) of GSD. The serum lipoprotein (LP) content was determined in all patients using analytical ultracentrifugation. Hyperlipoproteinaemia (HLP) was found in virtually all patients. Patients with Type I of GSD were found to have Types 2b and 4 of HLP; and patients with Type III of GSD, 2b Type of HLP. 2a Type of HLP was diagnosed in patients with GSD of VI and IX (X) Types. Patients with Type III GSD, in contrast to those with GSD of other types, had enhanced levels of Sf 12-20 LP. The levels of Sf 100-400 and Sf 20-100 LP were greatly increased only in patients with Type I GSD.

  16. Detection of Rickettsia rickettsii and Bartonella henselae in Rhipicephalus sanguineus ticks from California.

    PubMed

    Wikswo, Mary Elizabeth; Hu, Renjie; Metzger, Marco E; Eremeeva, Marina E

    2007-01-01

    Sixty-two questing adult Rhipicephalus sanguineus (Latreille) ticks were collected by direct removal from blades of turfgrass and adjacent concrete walkways at a suburban home in Riverside County, CA, and tested for the presence of Rickettsia, Bartonella, and Ehrlichia DNA. Polymerase chain reaction (PCR) was used to amplify fragments of the 17-kDa antigen gene and the rOmpA gene of the spotted fever group rickettsiae. One male tick contained R. rickettsii DNA; its genotype differed from R. rickettsii isolates found in Montana and Arizona that cause Rocky Mountain spotted fever and from Hlp#2 and 364D serotypes. One male tick and one female tick contained B. henselae DNA. No Ehrlichia platys or Ehrlichia canis DNAs were detected using nested PCR for their 16S rRNA genes. These findings extend the area where Rickettsia rickettsii may be vectored by Rh. sanguineus. Rh. sanguineus also may be infected with Bartonella henselae, a human pathogen that is typically associated with fleas and causes cat scratch disease.

  17. The effect of Ochratoxin A on antimicrobial polypeptide expression and resistance to water mold infection in channel catfish (Ictalurus punctatus).

    PubMed

    Zahran, Eman; Manning, Bruce; Seo, Jung-Kil; Noga, Edward J

    2016-10-01

    Mycotoxin contamination of agricultural commodities poses a serious risk to animal health, including aquaculture species. Ochratoxin A (OA) is the most immunotoxic ochratoxin, yet little is known about its effect on immune function in fish. Antimicrobial polypeptides (AMPPs) are one of the most potent, innate, host defense factors, yet very little is known about what types of chronic stressors affect their expression. Among the most prevalent and potent AMPPs in fish are histone-like proteins (HLPs). In this study, fish were fed 2, 4, or 8 mg OA/kg diet. Skin antibacterial activity and HLP-1 levels were measured on Days 0, 28 and 56. Feeding 2, 4 or 8 mg OA/kg diet resulted in significant growth depression, but higher levels (4 or 8 mg OA/kg diet) resulted in lowering feed intake (FI) and impaired feed conversion ratio. In addition, feeding 8 mg OA/kg diet increased susceptibility to experimental water mold (Saprolegnia) challenge, suggesting that OA toxicity might contribute to some saprolegnosis outbreaks. However, there were no changes in AMPP expression in any treatment group. Our data suggests that the increased disease susceptibility of channel catfish due to OA is probably due to mechanisms other than a direct effect on antimicrobial polypeptide expression.

  18. Conceptual design of initial opacity experiments on the national ignition facility

    NASA Astrophysics Data System (ADS)

    Heeter, R. F.; Bailey, J. E.; Craxton, R. S.; Devolder, B. G.; Dodd, E. S.; Garcia, E. M.; Huffman, E. J.; Iglesias, C. A.; King, J. A.; Kline, J. L.; Liedahl, D. A.; McKenty, P. W.; Opachich, Y. P.; Rochau, G. A.; Ross, P. W.; Schneider, M. B.; Sherrill, M. E.; Wilson, B. G.; Zhang, R.; Perry, T. S.

    2017-02-01

    Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative-convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures eV and electron densities 21~\\text{cm}-3$ . The iron will be probed using continuum X-rays emitted in a ps, diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design, of the NIF beams deliver 500 kJ to the mm diameter hohlraum, and the remaining directly drive the CH capsule with 200 kJ. Calculations indicate this capsule backlighter should outshine the iron sample, delivering a point-projection transmission opacity measurement to a time-integrated X-ray spectrometer viewing down the hohlraum axis. Preliminary experiments to develop the backlighter and hohlraum are underway, informing simulated measurements to guide the final design.

  19. High performance capsule implosions on the OMEGA Laser facility with rugby hohlraumsa)

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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 D2-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 ≈20× more deuterium (DD) neutrons than any previous indirectly driven campaign on OMEGA and ≈3× 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 H3e rather than D2 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)].

  20. LLE Review. Volume 68, July--September 1996

    SciTech Connect

    1996-07-01

    This volume of the LLE Review, covering the period of July-September 1996, includes a description of an important experiment carried out on OMEGA by researchers from LANL, LLNL, and LLE to demonstrate the feasibility of using OMEGA for indirect drive. Additional topics include tetrahedral hohlraums, the speckle properties of phase- converted laser beams, design criteria for SSD phase modulators, and the design of slab amplifiers. Highlights of the research presented in this issue are (1) Results from the proof-of-principle indirect- drive experiments in which up to 40 OMEGA beams were used to irradiate cylindrical hohlraums. Nova results were reproduced, and new capabilities not available on other lasers were demonstrated. (2) A discussion of tetrahedral hohlraums (spherical hohlraums with four laser entrance holes) as a means of achieving better capsule irradiation uniformity. Tetrahedral hohlraums also allow the use of all 60 OMEGA beams and may provide an alternate route to ignition on the NIF. (3) An analysis of the residual target irradiation nonuniformity due to the fine laser speckle remaining on the beam after being phase converted by the DPP`s. A model shows how a uniformly ablating plasma atmosphere reduces the speckle contribution to the effective time-averaged irradiation nonuniformity. (4) A discussion of the theory, design, manufacture, testing, and implementation of the microwave SSD phase modulators used on OMEGA for two-dimensional SSD. The modulators are capable of operating in the gigahertz frequency range. (5) A discussion of the design and performance of a large-aperture, high-gain Nd:glass zig-zag slab amplifier for materials testing. The design incorporates improvements from previous work in addition to improvements obtained from careful design choices guided by analytic calculations.

  1. Differential ablator-fuel adiabat tuning in indirect-drive implosions

    NASA Astrophysics Data System (ADS)

    Peterson, J. L.; Berzak Hopkins, L. F.; Jones, O. S.; Clark, D. S.

    2015-03-01

    We propose a design adjustment to the high foot laser pulse [T. R. Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014), 10.1103/PhysRevLett.112.055002] that is predicted to lower the fuel adiabat, increase compression and neutron production, but maintain similar ablation front growth. This is accomplished by lowering the laser power between the first and the second pulses (the "trough") so that the first shock remains strong initially but decays as it transits the ablator and enters the capsule fuel in a process similar to direct-drive "adiabat shaping" [S. E. Bodner et al., Phys. Plasmas 7, 2298 (2000), 10.1063/1.874063]. Integrated hohlraum simulations show that hohlraum cooling is sufficient to launch decaying shocks with adequate symmetry control, suggesting that adiabat shaping may be possible with indirect-drive implosions. Initial experiments show the efficacy of this technique.

  2. Towards an integrated model of the NIC layered implosions

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  3. Direct Drive Heavy-Ion-Beam Inertial Fusion at High Coupling Efficiency

    SciTech Connect

    Logan, B. Grant; Logan, B. Grant; Perkins, L.J.; Barnard, J.J.

    2007-06-25

    Issues with coupling efficiency, beam illumination symmetry and Rayleigh Taylor (RT) instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX ICF target physics code shows the ion range increasing four-fold during the drive pulse to keep ion energy deposition following closely behind the imploding ablation front, resulting in high coupling efficiencies (shell kinetic energy/incident beam energy of 16 to 18%). Ways to increase beam ion range while mitigating Rayleigh-Taylor instabilities are discussed for future work.

  4. Anisotropy of radiation emitted from planar wire arrays

    SciTech Connect

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

    2013-07-15

    The planar wire array (PWA) is a promising load for new multi-source inertial confinement fusion (ICF) hohlraums [B. Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The hohlraum radiation symmetry is an important issue for ICF. It was found that extreme ultraviolet and sub-keV photon emission from PWAs may have considerable anisotropy in the load azimuthal plane. This experimental result is obtained on the UNR 1–1.7 MA Zebra generator. The time-dependent anisotropy effect is detected. This feature is studied in 2D numerical simulations and can be explained by initial anisotropy of implosion of those non-cylindrical loads radiating essentially as surface sources in sub-keV quanta and also by radiation absorption in cold magnetized plasma tails forming in the direction of magnetic compression.

  5. Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures

    SciTech Connect

    Bhandarkar, Suhas; Betcher, Jacob; Smith, Ryan; Lairson, Bruce; Ayers, Travis

    2016-06-30

    Targets for ICF shots on NIF typically use ~500nm thin polyimide films with a coating of 25nm of aluminum as windows that seal the laser entrance hole or LEH. Their role is to contain the hohlraum gas and minimize the extraneous infra-red radiation getting in. This is necessary to precisely control the hohlraum thermal environment for layering inside the capsule with solid deuterium-tritium at 18K. Here, we use our empirical data on the bulging behavior of these foils under various different conditions to develop models to capture the complex viscoelastic behavior of these films at both ambient and cryogenic temperatures. The constitutive equations derived from these models give us the ability to quantitatively specify the film’s behavior during the fielding of these targets and set the best parameters for new target designs.

  6. Interplay of Laser-Plasma Interactions and Inertial Fusion Hydrodynamics

    DOE PAGES

    Strozzi, D. J.; Bailey, D. S.; Michel, P.; ...

    2017-01-12

    The effects of laser-plasma interactions (LPI) on the dynamics of inertial confinement fusion hohlraums are investigated in this work via a new approach that self-consistently couples reduced LPI models into radiation-hydrodynamics numerical codes. The interplay between hydrodynamics and LPI—specifically stimulated Raman scatter and crossed-beam energy transfer (CBET)—mostly occurs via momentum and energy deposition into Langmuir and ion acoustic waves. This spatially redistributes energy coupling to the target, which affects the background plasma conditions and thus, modifies laser propagation. In conclusion, this model shows reduced CBET and significant laser energy depletion by Langmuir waves, which reduce the discrepancy between modeling andmore » data from hohlraum experiments on wall x-ray emission and capsule implosion shape.« less

  7. Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures

    DOE PAGES

    Bhandarkar, Suhas; Betcher, Jacob; Smith, Ryan; ...

    2016-06-30

    Targets for ICF shots on NIF typically use ~500nm thin polyimide films with a coating of 25nm of aluminum as windows that seal the laser entrance hole or LEH. Their role is to contain the hohlraum gas and minimize the extraneous infra-red radiation getting in. This is necessary to precisely control the hohlraum thermal environment for layering inside the capsule with solid deuterium-tritium at 18K. Here, we use our empirical data on the bulging behavior of these foils under various different conditions to develop models to capture the complex viscoelastic behavior of these films at both ambient and cryogenic temperatures.more » The constitutive equations derived from these models give us the ability to quantitatively specify the film’s behavior during the fielding of these targets and set the best parameters for new target designs.« less

  8. Investigation of radiation flux in certain band via the preheat of aluminum sample

    SciTech Connect

    Zhang, Chen; Wang, Zhebin; Wang, Feng; Peng, Xiaoshi; Jiang, Shaoen; Ding, Yongkun; Zhao, Bin; Hu, Guangyue; Zheng, Jian

    2013-12-15

    Quantitative evaluation of the fractions of high energy x-rays in a hohlraum is crucial to the indirect driven-drive scheme of inertial confinement fusion and many other applications in high energy density physics. Preheat of a sample due to x-rays sensitively depends on optical thin photons. Analyzing the motion of a sample due to preheat can thus provide valuable information of those x-rays. In this article, we propose a method to infer the temporal evolution of the x-ray fluxes in the bands of our interest. By matching the simulation results to the motions of an aluminum sample, we can infer the time-resolved x-ray fluxes around the aluminum K-edge and the gold M-band inside the hohlraum.

  9. Using view factor analysis to understand symmetry for NIF Indirect Drive

    NASA Astrophysics Data System (ADS)

    Thomas, Cliff; Edwards, Michael

    2007-11-01

    To achieve ignition, a NIF capsule requires a high degree of drive symmetry. In practice, this is obtained with the careful balance of several parameters (such as the number of laser cones, and/or the distribution of laser power between separate laser cones). Since the available parameter space is large, it can be difficult to optimize the symmetry using full-physics models. To motivate the further investigation of the available parameter space, and to provide greater insight on symmetry, this study considers a view factor description of radiation transport for indirect drive. Using this approach, the flux on the capsule can be understood as a function of laser pointing, laser spot size, cone balance, and hohlraum geometry (hohlraum length, capsule radius, and LEH size). As a result, avenues for tuning symmetry are explained, and suggestions are made to improve symmetry through the full laser drive.

  10. Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures

    SciTech Connect

    Bhandarkar, Suhas; Betcher, Jacob; Smith, Ryan; Lairson, Bruce; Ayers, Travis

    2016-06-30

    Targets for ICF shots on NIF typically use ~500nm thin polyimide films with a coating of 25nm of aluminum as windows that seal the laser entrance hole or LEH. Their role is to contain the hohlraum gas and minimize the extraneous infra-red radiation getting in. This is necessary to precisely control the hohlraum thermal environment for layering inside the capsule with solid deuterium-tritium at 18K. Here, we use our empirical data on the bulging behavior of these foils under various different conditions to develop models to capture the complex viscoelastic behavior of these films at both ambient and cryogenic temperatures. The constitutive equations derived from these models give us the ability to quantitatively specify the film’s behavior during the fielding of these targets and set the best parameters for new target designs.

  11. Images of the laser entrance hole from the static x-ray imager at NIF.

    PubMed

    Schneider, M B; Jones, O S; Meezan, N B; Milovich, J L; Town, R P; Alvarez, S S; Beeler, R G; Bradley, D K; Celeste, J R; Dixit, S N; Edwards, M J; Haugh, M J; Kalantar, D H; Kline, J L; Kyrala, G A; Landen, O L; MacGowan, B J; Michel, P; Moody, J D; Oberhelman, S K; Piston, K W; Pivovaroff, M J; Suter, L J; Teruya, A T; Thomas, C A; Vernon, S P; Warrick, A L; Widmann, K; Wood, R D; Young, B K

    2010-10-01

    The static x-ray imager at the National Ignition Facility is a pinhole camera using a CCD detector to obtain images of Hohlraum wall x-ray drive illumination patterns seen through the laser entrance hole (LEH). Carefully chosen filters, combined with the CCD response, allow recording images in the x-ray range of 3-5 keV with 60 μm spatial resolution. The routines used to obtain the apparent size of the backlit LEH and the location and intensity of beam spots are discussed and compared to predictions. A new soft x-ray channel centered at 870 eV (near the x-ray peak of a 300 eV temperature ignition Hohlraum) is discussed.

  12. Nuclear science research with dynamic high energy density plasmas at NIF

    NASA Astrophysics Data System (ADS)

    Shaughnessy, D. A.; Gharibyan, N.; Moody, K. J.; Despotopulos, J. D.; Grant, P. M.; Yeamans, C. B.; Berzak Hopkins, L.; Cerjan, C. J.; Schneider, D. H. G.; Faye, S.

    2016-05-01

    Nuclear reaction measurements are performed at the National Ignition Facility in a high energy density plasma environment by adding target materials to the outside of the hohlraum thermo-mechanical package on an indirect-drive exploding pusher shot. Materials are activated with 14.1-MeV neutrons and the post-shot debris is collected via the Solid Radiochemistry diagnostic, which consists of metal discs fielded 50 cm from target chamber center. The discs are removed post-shot and analyzed via radiation counting and mass spectrometry. Results from a shot using Nd and Tm foils as targets are presented, which indicate enhanced collection of the debris in the line of sight of a given collector. The capsule performance was not diminished due to the extra material. This provides a platform for future measurements of nuclear reaction data through the use of experimental packages mounted external to the hohlraum.

  13. New designs of LMJ targets for early ignition experiments

    NASA Astrophysics Data System (ADS)

    C-Clérouin, C.; Bonnefille, M.; Dattolo, E.; Fremerye, P.; Galmiche, D.; Gauthier, P.; Giorla, J.; Laffite, S.; Liberatore, S.; Loiseau, P.; Malinie, G.; Masse, L.; Poggi, F.; Seytor, P.

    2008-05-01

    The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 40 laser quads, delivering up to 1.4MJ and 380TW. New targets needing reduced laser energy with only a small decrease in robustness are then designed for this purpose. A first strategy is to use scaled-down cylindrical hohlraums and capsules, taking advantage of our better understanding of the problem, set on theoretical modelling, simulations and experiments. Another strategy is to work specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, which is with parametric instabilities a crucial drawback of indirect drive. An alternative design is proposed, made up of the nominal 60 quads capsule, named A1040, in a rugby-shaped hohlraum. Robustness evaluations of these different targets are in progress.

  14. eHXI: A permanently installed, hard x-ray imager for the National Ignition Facility

    SciTech Connect

    Doppner, T.; Bachmann, B.; Albert, F.; Bell, P.; Burns, S.; Celeste, J.; Chow, R.; Divol, L.; Dewald, E. L.; Hohenberger, M.; Izumi, N.; LaCaille, G.; Landen, O. L.; Palmer, N.; Park, H. -S.; Thomas, C. A.; Huntington, C.

    2016-06-14

    We have designed and built a multi-pinhole imaging system for high energy x-rays (≥ 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. Lastly, eHXI provides valuable information on hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.

  15. Direct drive heavy-ion-beam inertial fusion at high coupling efficiency

    SciTech Connect

    Logan, B.G.; Perkins, L.J.; Barnard, J.J.

    2008-05-16

    Issues with coupling efficiency, beam illumination symmetry, and Rayleigh-Taylor instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy-ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX inertial confinement fusion target physics code shows the ion range increasing fourfold during the drive pulse to keep ion energy deposition following closely behind the imploding ablation front, resulting in high coupling efficiencies (shell kinetic energy/incident beam energy of 16% to 18%). Ways to increase beam ion range while mitigating Rayleigh-Taylor instabilities are discussed for future work.

  16. Z-Pinch Driven Inertial Confinement Fusion Target Physics Research at Sandia National Laboratories

    SciTech Connect

    Alberts, T.E.; Asay, J.R.; Baca, P.M.; Baker, K.L.; Breeze, S.P.; Chandler, G.A.; Cook, D.L.; Cooper, G.W.; Deeney, C.; Derzon, M.S.; Douglas, M.R.; Fehl, D.L.; Gilliland, T.; Hebron, D.E.; Hurst, M.J.; Jobe, D.O.; Kellogg, J.W.; Lash, J.S.; Lazier, S.E.; Leeper, R.J.; Matzen, M.K.; McDaniel, D.H.; McGurn, J.S.; Mehlhorn, T.A.; Moats, A.R.; Mock, R.C.; Muron, D.J.; Nash, T.J.; Olson, R.E.; Porter, J.L.; Quintenz, J.P.; Reyers, P.V.; Ruggles, L.E.; Ruiz, C.L.; Sandford, T.W.L.; Schmidlapp, F.A.; Seamen, J.F.; Spielman, R.B.; Stark, M.A.; Struve, K.W.; Stygar, W.A.; Tibbetts-Russell, D.R.; Torres, J.A.; Vargas, M.; Wagoner, T.C.; Wakefield, C.

    1998-10-27

    Three hohlraum concepts are being pursued at Sandia National Laboratories (SNL) to investigate the possibility of using pulsed power driven magnetic implosions (z-pinches) to drive high gain targets capable of yields in the range of 200-1000 MJ. This research is being conducted on SNL'S.Z facility that is capable of driving peak currents of 20 MA in z-pinch loads producing implosion velocities as high as 7.5X 107 cm/s, x-ray energies approaching 2 MJ, and x-ray powers exceeding 200 TW. This paper will discuss each of these hohlraum concepts and will overview the experiments that have been conducted on these systems to date.

  17. 2D X-ray radiography of imploding capsules at the national ignition facility.

    PubMed

    Rygg, J R; Jones, O S; Field, J E; Barrios, M A; Benedetti, L R; Collins, G W; Eder, D C; Edwards, M J; Kline, J L; Kroll, J J; Landen, O L; Ma, T; Pak, A; Peterson, J L; Raman, K; Town, R P J; Bradley, D K

    2014-05-16

    First measurements of the in-flight shape of imploding inertial confinement fusion (ICF) capsules at the National Ignition Facility (NIF) were obtained by using two-dimensional x-ray radiography. The sequence of area-backlit, time-gated pinhole images is analyzed for implosion velocity, low-mode shape and density asymmetries, and the absolute offset and center-of-mass velocity of the capsule shell. The in-flight shell is often observed to be asymmetric even when the concomitant core self-emission is round. A ∼ 15 μm shell asymmetry amplitude of the Y(40) spherical harmonic mode was observed for standard NIF ICF hohlraums at a shell radius of ∼ 200 μm (capsule at ∼ 5× radial compression). This asymmetry is mitigated by a ∼ 10% increase in the hohlraum length.

  18. Development of X-ray tracer diagnostics for radiatively-driven ablator experiments [annual report FY1998

    SciTech Connect

    J.J. MacFarlane; D.H. Cohen; P. Wang; G.A. Moses; R.R. Peterson; P.A. Jaanimagi; O.L. Langen; R.E. Olson; T.J. Murphy; G.R. Magelssen; N.D. Delamater

    1999-05-01

    This report covers fiscal year 1998 of our ongoing project to develop tracer X-ray spectroscopic diagnostics for hohlraum environments. This effort focused on an experimental campaign carried out at OMEGA on 25--27 August 1998. This phase of the project heavily emphasized experimental design, diagnostic development, and target fabrication, as well as building up numerical models for the experiments. The spectral diagnostic under development involves using two thin (few 1000 {angstrom}) mid-Z tracers in two witness plates mounted on the side of a hohlraum with the tracers' K{sub a} absorption features seen against an X-ray backlighter. The absorption data are used to sample the time-dependent, localized properties of each witness plate as a radiation wave ablates it. The experiments represented the first application of this diagnostic, in this case to side-by-side doped and undoped plastic to investigate the effects of capsule ablator dopants.

  19. A High-Resolution Integrated Model of the National Ignition Campaign Cryogenic Layered Experiments

    DOE PAGES

    Jones, O. S.; Callahan, D. A.; Cerjan, C. J.; ...

    2012-05-29

    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.more » Simulated experimental values were extracted from the simulation and compared against the experiment. The model adjustments brought much of the simulated data into closer agreement with the experiment, with the notable exception of the measured yields, which were 15-40% of the calculated yields.« less

  20. Capsule Performance Optimization in the National Ignition Campaign

    SciTech Connect

    Landen, O L; MacGowan, B J; Haan, S W; Edwards, J

    2009-10-13

    A capsule performance optimization campaign will be conducted at the National Ignition Facility to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

  1. The Bigfoot Drive; Experimental Results

    NASA Astrophysics Data System (ADS)

    Baker, Kevin; Thomas, Cliff; Khan, Shahab; Casey, Daniel; Spears, Brian; Nora, Ryan; Munro, Davis; Eder, David; Milovich, Jose; Berger, Dick; Strozzi, David; Goyon, Clement; Turnbull, David; Ma, Tammy; Izumi, Nobuhiko; Benedetti, Robin; Millot, Marius; Celliers, Peter; Yeamans, Charles; Hatarik, Robert; Landen, Nino; Hurricane, Omar; Callahan, Debbie

    2016-10-01

    The Bigfoot platform was developed on the National Ignition Facility to investigate low convergence, high adiabat, high rhoR hotspot implosions. This platform was designed to be less susceptible to wall motion, LPI and CBET and to be more robust against capsule hydrodynamic instabilities. To date experimental studies have been carried out at two hohlraum scales, a 5.75 and 5.4 mm diameter hohlraum. We will present experimental results from these tuning campaigns including the shape vs. cone fraction, surrogacy comparisons of self-emission from the capsules vs. radiography of the imploding capsule and doped vs. undoped capsules. Prepared by LLNL under Contract DE-AC52-07NA27344.

  2. Capsule performance optimization in the national ignition campaign

    NASA Astrophysics Data System (ADS)

    Landen, O. L.; MacGowan, B. J.; Haan, S. W.; Edwards, J.

    2010-08-01

    A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

  3. Imaging of High-Z doped, Imploded Capsule Cores

    NASA Astrophysics Data System (ADS)

    Prisbrey, Shon T.; Edwards, M. John; Suter, Larry J.

    2006-10-01

    The ability to correctly ascertain the shape of imploded fusion capsules is critical to be able to achieve the spherical symmetry needed to maximize the energy yield of proposed fusion experiments for the National Ignition Facility. Implosion of the capsule creates a hot, dense core. The introduction of a high-Z dopant into the gas-filled core of the capsule increases the amount of bremsstrahlung radiation produced in the core and should make the imaging of the imploded core easier. Images of the imploded core can then be analyzed to ascertain the symmetry of the implosion. We calculate that the addition of Ne gas into a deuterium gas core will increase the amount of radiation emission while preserving the surrogacy of the radiation and hydrodynamics in the indirect drive NIF hohlraum in the proposed cryogenic hohlraums. The increased emission will more easily enable measurement of asymmetries and tuning of the implosion.

  4. Differential ablator-fuel adiabat tuning in indirect-drive implosions.

    PubMed

    Peterson, J L; Berzak Hopkins, L F; Jones, O S; Clark, D S

    2015-03-01

    We propose a design adjustment to the high foot laser pulse [T. R. Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014)] that is predicted to lower the fuel adiabat, increase compression and neutron production, but maintain similar ablation front growth. This is accomplished by lowering the laser power between the first and the second pulses (the "trough") so that the first shock remains strong initially but decays as it transits the ablator and enters the capsule fuel in a process similar to direct-drive "adiabat shaping" [S. E. Bodner et al., Phys. Plasmas 7, 2298 (2000)]. Integrated hohlraum simulations show that hohlraum cooling is sufficient to launch decaying shocks with adequate symmetry control, suggesting that adiabat shaping may be possible with indirect-drive implosions. Initial experiments show the efficacy of this technique.

  5. Total hemispherical emittance measured at high temperatures by the calorimetric method

    SciTech Connect

    DiFilippo, F.; Mirtich, M.J.; Banks, B.A.; Stidham, C.; Kussmaul, M.

    1994-09-01

    A calorimetric vacuum emissometer (CVE) capable of measuring total hemispherical emittance of surfaces at elevated temperatures was designed, built, and tested. Several materials with a wide range of emittances were measured in the CVE between 773 to 923 K. These results were compared to values calculated from spectral emittance curves measured in a room temperature Hohlraum reflectometer and in an open-air elevated temperature emissometer. The results differed by as much as 0.2 for some materials but were in closer agreement for the more highly-emitting, diffuse-reflecting samples. The differences were attributed to temperature, atmospheric, and directional effects, and errors in the Hohlraum and emissometer measurements ({+-} 5 percent). The probable error of the CVE measurements was typically less than 1 percent.

  6. Total hemispherical emittance measured at high temperatures by the calorimetric method

    NASA Technical Reports Server (NTRS)

    Difilippo, Frank; Mirtich, Michael J.; Banks, Bruce A.; Stidham, Curtis; Kussmaul, Michael

    1989-01-01

    A calorimetric vacuum emissometer (CVE) capable of measuring total hemispherical emittance of surfaces at elevated temperatures was designed, built, and tested. Several materials with a wide range of emittances were measured in the CVE between 773 to 923 K. These results were compared to values calculated from spectral emittance curves measured in a room temperature Hohlraum reflectometer and in an open-air elevated temperature emissometer. The results differed by as much as 0.2 for some materials but were in closer agreement for the more highly-emitting, diffuse-reflecting samples. The differences were attributed to temperature, atmospheric, and directional effects, and errors in the Hohlraum and emissometer measurements (plus or minus 5 percent). The probable error of the CVE measurements was typically less than 1 percent.

  7. Interplay of Laser-Plasma Interactions and Inertial Fusion Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Strozzi, D. J.; Bailey, D. S.; Michel, P.; Divol, L.; Sepke, S. M.; Kerbel, G. D.; Thomas, C. A.; Ralph, J. E.; Moody, J. D.; Schneider, M. B.

    2017-01-01

    The effects of laser-plasma interactions (LPI) on the dynamics of inertial confinement fusion hohlraums are investigated via a new approach that self-consistently couples reduced LPI models into radiation-hydrodynamics numerical codes. The interplay between hydrodynamics and LPI—specifically stimulated Raman scatter and crossed-beam energy transfer (CBET)—mostly occurs via momentum and energy deposition into Langmuir and ion acoustic waves. This spatially redistributes energy coupling to the target, which affects the background plasma conditions and thus, modifies laser propagation. This model shows reduced CBET and significant laser energy depletion by Langmuir waves, which reduce the discrepancy between modeling and data from hohlraum experiments on wall x-ray emission and capsule implosion shape.

  8. National Ignition Facility Target Design and Fabrication

    SciTech Connect

    Cook, R C; Kozioziemski, B J; Nikroo, A; Wilkens, H L; Bhandarkar, S; Forsman, A C; Haan, S W; Hoppe, M L; Huang, H; Mapoles, E; Moody, J D; Sater, J D; Seugling, R M; Stephens, R B; Takagi, M; Xu, H W

    2007-12-10

    The current capsule target design for the first ignition experiments at the NIF Facility beginning in 2009 will be a copper-doped beryllium capsule, roughly 2 mm in diameter with 160-{micro}m walls. The capsule will have a 75-{micro}m layer of solid DT on the inside surface, and the capsule will driven with x-rays generated from a gold/uranium cocktail hohlraum. The design specifications are extremely rigorous, particularly with respect to interfaces, which must be very smooth to inhibit Rayleigh-Taylor instability growth. This paper outlines the current design, and focuses on the challenges and advances in capsule fabrication and characterization; hohlraum fabrication, and D-T layering and characterization.

  9. Laser-Plasma Interactions in High-Energy Density Plasmas

    SciTech Connect

    Constantin, C G; Baldis, H A; Schneider, M B; Hinkel, D E; Langdon, A B; Seka, W; Bahr, R; Depierreaux, S

    2005-08-24

    Laser-plasma interactions (LPI) have been studied experimentally in high-temperature, high-energy density plasmas. The studies have been performed using the Omega laser at the Laboratory for Laser Energetics (LLE), Rochester, NY. Up to 10 TW of power was incident upon reduced-scale hohlraums, distributed in three laser beam cones. The hot hohlraums fill quickly with plasma. Late in the laser pulse, most of the laser energy is deposited at the laser entrance hole, where most of the LPI takes place. Due to the high electron temperature, the stimulated Raman scattering (SRS) spectrum extends well beyond {omega}{sub 0}/2, due to the Bohm-Gross shift. This high-temperature, high-energy density regime provides a unique opportunity to study LPI beyond inertial confinement fusion (ICF) conditions.

  10. eHXI: a permanently installed, hard x-ray imager for the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Döppner, T.; Bachmann, B.; Albert, F.; Bell, P.; Burns, S.; Celeste, J.; Chow, R.; Divol, L.; Dewald, E. L.; Hohenberger, M.; Huntington, C. M.; Izumi, N.; LaCaille, G.; Landen, O. L.; Palmer, N.; Park, H.-S.; Thomas, C. A.

    2016-06-01

    We have designed and built a multi-pinhole imaging system for high energy x-rays (>= 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. eHXI provides valuable information on hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.

  11. Symmetry Experiments on Omega with LMJ like Multiple Beam Cones Irradation

    SciTech Connect

    Richard, A L; Jadaud, J P; Dague, N; Monteil, M C; Turner, R E; Bradley, D; Wallace, R J; Landen, O L; Soures, J M; Morse, S; Pien, G

    2000-07-17

    We carried out a set of experiments on the Omega laser facility at Rochester with Laser MegaJoule (LMJ) like indirect drive irradiation. We studied the irradiation non-uniformity with the foam ball radiography technique and the implosion symmetry with (D{sub 2} + Argon) filled capsules core emission. Cylindrical ''Nova scale 1'' thin wall hohlraums were used. Forty of the Omega beams, arranged in three cones on each side of the hohlraum (5, 5, and lo), were used to create the X-ray drive. Eight additional beams were used on a Ti source to radiograph the foam balls. The shaped laser pulse was about 3 ns duration. The radiation drive was measured on each shot. The images were recorded with a 5 prn resolution Gated X-ray Imager coupled to a CCD camera.

  12. Results from Recent NIF Shock Timing Experiments

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Celliers, P. M.; Boehly, T. R.; Kline, J. L.; Bowers, M. W.; Le Pape, S.; Farley, D. R.; MacKinnon, A. J.; Moody, J. D.; Eggert, J. H.; Munro, D. H.; Jones, O. S.; Milovich, J. L.; Clark, D.; Nikroo, A.; Moreno, K. A.; Kroll, J. J.; Hamza, A. V.; Barker, D. A.; Landen, O. L.; Edwards, M. J.; Meyerhofer, D. D.

    2011-10-01

    Experiments are underway to tune the shock timing of capsule implosions on the National Ignition Facility (NIF). These experiments use a modified cryogenic hohlraum geometry designed to precisely match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to multiple shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of all four shocks is diagnosed with VISAR (Velocity Interferometer System for Any Reflector). The tuned pulse shape resulting from these experiments has been tested in ignition capsule implosions and demonstrates a considerable improvement in fuel adiabat. Experimental results and comparisons with numerical simulation are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  13. Initial NIF Shock Timing Experiments: Comparison with Simulation

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Celliers, P. M.; Boehly, T. R.; Datte, P. S.; Bowers, M. W.; Olson, R. E.; Munro, D. H.; Milovich, J. L.; Jones, O. S.; Nikroo, A.; Kroll, J. J.; Horner, J. B.; Hamza, A. V.; Bhandarkar, S. D.; Giraldez, E.; Castro, C.; Gibson, C. R.; Eggert, J. H.; Smith, R. F.; Park, H.-S.; Young, B. K.; Hsing, W. W.; Landen, O. L.; Meyerhofer, D. D.

    2010-11-01

    Initial experiments are underway to demonstrate the techniques required to tune the shock timing of capsule implosions on the National Ignition Facility (NIF). These experiments use a modified cryogenic hohlraum geometry designed to precisely match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shocks is diagnosed with VISAR (Velocity Interferometer System for Any Reflector) and DANTE. The results of these measurements will be used to set the precision pulse shape for ignition capsule implosions to follow. Experimental results and comparisons with numerical simulation are presented.

  14. eHXI: A permanently installed, hard x-ray imager for the National Ignition Facility

    DOE PAGES

    Doppner, T.; Bachmann, B.; Albert, F.; ...

    2016-06-14

    We have designed and built a multi-pinhole imaging system for high energy x-rays (≥ 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. Lastly, eHXI provides valuable information onmore » hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.« less

  15. eHXI: A permanently installed, hard x-ray imager for the National Ignition Facility

    SciTech Connect

    Doppner, T.; Bachmann, B.; Albert, F.; Bell, P.; Burns, S.; Celeste, J.; Chow, R.; Divol, L.; Dewald, E. L.; Hohenberger, M.; Izumi, N.; LaCaille, G.; Landen, O. L.; Palmer, N.; Park, H. -S.; Thomas, C. A.; Huntington, C.

    2016-06-14

    We have designed and built a multi-pinhole imaging system for high energy x-rays (≥ 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. Lastly, eHXI provides valuable information on hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.

  16. Radiation sources with planar wire arrays and planar foils for inertial confinement fusion and high energy density physics research

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Chuvatin, A. S.; Safronova, A. S.; Rudakov, L. I.; Esaulov, A. A.; Velikovich, A. L.; Shrestha, I.; Astanovitsky, A.; Osborne, G. C.; Shlyaptseva, V. V.; Weller, M. E.; Keim, S.; Stafford, A.; Cooper, M.

    2014-03-01

    This article reports on the joint success of two independent lines of research, each of them being a multi-year international effort. One of these is the development of innovative sources, such as planar wire arrays (PWAs). PWAs turned out to be a prolific radiator, which act mainly as a resistor, even though the physical mechanism of efficient magnetic energy conversion into radiation still remains unclear. We review the results of our extensive studies of PWAs. We also report the new results of the experimental comparison PWAs with planar foil liners (another promising alternative to wire array loads at multi-mega-ampere generators). Pioneered at UNR, the PWA Z-pinch loads have later been tested at the Sandia National Laboratories (SNL) on the Saturn generator, on GIT-12 machine in Russia, and on the QiangGuang-1 generator in China, always successfully. Another of these is the drastic improvement in energy efficiency of pulsed-power systems, which started in early 1980s with Zucker's experiments at Naval Research Laboratory (NRL). Successful continuation of this approach was the Load Current Multiplier (LCM) proposed by Chuvatin in collaboration with Rudakov and Weber from NRL. The 100 ns LCM was integrated into the Zebra generator, which almost doubled the plasma load current, from 0.9 to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum radiation source for ICF, as jointly proposed by SNL and UNR [Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The first successful proof-of-the-principle experimental implementation of new hohlraum concept at university-scale generator Zebra/LCM is demonstrated. A numerical simulation capability with VisRaD code (from PRISM Co.) established at UNR allowed for the study of hohlraum coupling physics and provides the possibility of optimization of a new hohlraum. Future studies are discussed.

  17. Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility

    SciTech Connect

    Gharibyan, N.; Shaughnessy, D. A.; Moody, K. J.; Grant, P. M.; Despotopulos, J. D.; Faye, S. A.; Jedlovec, D. R.; Yeamans, C. B.

    2016-08-05

    The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. As a result, the collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

  18. Radiation sources with planar wire arrays and planar foils for inertial confinement fusion and high energy density physics research

    SciTech Connect

    Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Shrestha, I.; Astanovitsky, A.; Osborne, G. C.; Shlyaptseva, V. V.; Weller, M. E.; Keim, S.; Stafford, A.; Cooper, M.; Chuvatin, A. S.; Rudakov, L. I.; Velikovich, A. L.

    2014-03-15

    This article reports on the joint success of two independent lines of research, each of them being a multi-year international effort. One of these is the development of innovative sources, such as planar wire arrays (PWAs). PWAs turned out to be a prolific radiator, which act mainly as a resistor, even though the physical mechanism of efficient magnetic energy conversion into radiation still remains unclear. We review the results of our extensive studies of PWAs. We also report the new results of the experimental comparison PWAs with planar foil liners (another promising alternative to wire array loads at multi-mega-ampere generators). Pioneered at UNR, the PWA Z-pinch loads have later been tested at the Sandia National Laboratories (SNL) on the Saturn generator, on GIT-12 machine in Russia, and on the QiangGuang-1 generator in China, always successfully. Another of these is the drastic improvement in energy efficiency of pulsed-power systems, which started in early 1980s with Zucker's experiments at Naval Research Laboratory (NRL). Successful continuation of this approach was the Load Current Multiplier (LCM) proposed by Chuvatin in collaboration with Rudakov and Weber from NRL. The 100 ns LCM was integrated into the Zebra generator, which almost doubled the plasma load current, from 0.9 to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum radiation source for ICF, as jointly proposed by SNL and UNR [Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The first successful proof-of-the-principle experimental implementation of new hohlraum concept at university-scale generator Zebra/LCM is demonstrated. A numerical simulation capability with VisRaD code (from PRISM Co.) established at UNR allowed for the study of hohlraum coupling physics and provides the possibility of optimization of a new hohlraum. Future studies are discussed.

  19. Science and code validation program to secure ignition on LMJ

    NASA Astrophysics Data System (ADS)

    Lefebvre, E.; Boniface, C.; Bonnefille, M.; Casner, A.; Esnault, C.; Galmiche, D.; Gauthier, P.; Girard, F.; Gisbert, R.; Leidinger, J.-P.; Loiseau, P.; Masse, L.; Masson-Laborde, P.-E.; Mignon, P.; Monteil, M.-C.; Seytor, P.; Tassin, V.

    2016-03-01

    The CEA/DAM ICF experimental program is currently conducted on LIL and Omega with the goal of improving our simulation tool, the FCI2 code. In this effort, we focus on typical ICF observables: hohlraum radiation drive history, capsule core shape and neutron emission history, hydrodynamic instability growth. In addition to integrated experiment, specific designs are also helpful to pinpoint a particular phenomenon. In this article, we review our current efforts and status, and our future projects on Omega and LMJ.

  20. Progress in the Science and Technology of Direct Drive Laser Fusion with the KrF Laser

    DTIC Science & Technology

    2010-12-01

    important parameters KrF technology leads) Direct Laser Drive is a better choice for Energy Indirect Drive (initial path for NIF ) Laser Beams x-rays Hohlraum...Pellet Direct Drive (IFE) Laser Beams Pellet .. • ID Ignition being explored on NIF • Providing high enough gain for pure fusion energy is...challenging. • DD Ignition physics can be explored on NIF . • More efficient use of laser light, and greater flexibility in applying drive provides potential for

  1. Indirect drive ignition at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.; Patel, P. K.; Callahan, D. A.; Hsing, W. W.; Town, R. P. J.; Albert, F.; Amendt, P. A.; Berzak Hopkins, L. F.; Bradley, D. K.; Casey, D. T.; Clark, D. S.; Dewald, E. L.; Dittrich, T. R.; Divol, L.; Döppner, T.; Field, J. E.; Haan, S. W.; Hall, G. N.; Hammel, B. A.; Hinkel, D. E.; Ho, D. D.; Hohenberger, M.; Izumi, N.; Jones, O. S.; Khan, S. F.; Kline, J. L.; Kritcher, A. L.; Landen, O. L.; LePape, S.; Ma, T.; MacKinnon, A. J.; MacPhee, A. G.; Masse, L.; Milovich, J. L.; Nikroo, A.; Pak, A.; Park, H.-S.; Peterson, J. L.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Smalyuk, V. A.; Spears, B. K.; Stadermann, M.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Turnbull, D. P.; Weber, C. R.

    2017-01-01

    This paper reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program’s forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v  >  350 km s-1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seeded by target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009-2012. Experiments using a ‘high-foot’ drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. Future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.

  2. Inertial confinement fusion ablator physics experiments on Saturn and Nova

    SciTech Connect

    Olson, R.E.; Porter, J.L.; Chandler, G.A.; Fehl, D.L.; Jobe, D.O.; Leeper, R.J.; Matzen, M.K.; McGurn, J.S.; Noack, D.D.; Ruggles, L.E.; Sawyer, P.; Torres, J.A.; Vargas, M.; Zagar, D.M.; Kornblum, H.N.; Orzechowski, T.J.; Phillion, D.W.; Suter, L.J.; Thiessen, A.R.; Wallace, R.J.

    1997-05-01

    The Saturn pulsed power accelerator [R. B. Spielman {ital et al.}, in {ital Proceedings of the 2nd International Conference on Dense} Z-{ital pinches}, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] at Sandia National Laboratories (SNL) and the Nova laser [J. T. Hunt and D. R. Speck, Opt. Eng. {bold 28}, 461 (1989)] at Lawrence Livermore National Laboratory (LLNL) have been used to explore techniques for studying the behavior of ablator material in x-ray radiation environments comparable in magnitude, spectrum, and duration to those that would be experienced in National Ignition Facility (NIF) hohlraums [J. D. Lindl, Phys. Plasmas {bold 2}, 3933 (1995)]. The large x-ray outputs available from the Saturn pulsed-power-driven z pinch have enabled us to drive hohlraums of full NIF ignition scale size at radiation temperatures and time scales comparable to those required for the low-power foot pulse of an ignition capsule. The high-intensity drives available in the Nova laser have allowed us to study capsule ablator physics in smaller-scale hohlraums at radiation temperatures and time scales relevant to the peak power pulse for an ignition capsule. Taken together, these experiments have pointed the way to possible techniques for testing radiation-hydrodynamics code predictions of radiation flow, opacity, equation of state, and ablator shock velocity over the range of radiation environments that will be encountered in a NIF hohlraum. {copyright} {ital 1997 American Institute of Physics.}

  3. Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility

    DOE PAGES

    Gharibyan, N.; Shaughnessy, D. A.; Moody, K. J.; ...

    2016-08-05

    The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. As a result, the collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

  4. Indirect drive ignition at the National Ignition Facility

    DOE PAGES

    Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.; ...

    2016-10-27

    This article reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program's forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v > 350 km s-1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seeded bymore » target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009–2012. Experiments using a 'high-foot' drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. In conclusion, future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.« less

  5. Indirect drive ignition at the National Ignition Facility

    SciTech Connect

    Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.; Patel, P. K.; Callahan, D. A.; Hsing, W. W.; Town, R. P. J.; Albert, F.; Amendt, P. A.; Berzak Hopkins, L. F.; Bradley, D. K.; Casey, D. T.; Clark, D. S.; Dewald, E. L.; Dittrich, T. R.; Divol, L.; Döppner, T.; Field, J. E.; Haan, S. W.; Hall, G. N.; Hammel, B. A.; Hinkel, D. E.; Ho, D. D.; Hohenberger, M.; Izumi, N.; Jones, O. S.; Khan, S. F.; Kline, J. L.; Kritcher, A. L.; Landen, O. L.; LePape, S.; Ma, T.; MacKinnon, A. J.; MacPhee, A. G.; Masse, L.; Milovich, J. L.; Nikroo, A.; Pak, A.; Park, H-S; Peterson, J. L.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Smalyuk, V. A.; Spears, B. K.; Stadermann, M.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Turnbull, D. P.; Weber, C. R.

    2016-10-27

    This article reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program's forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v > 350 km s-1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seeded by target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009–2012. Experiments using a 'high-foot' drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. In conclusion, future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.

  6. Capsule Performance Optimization for the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Landen, Otto

    2009-11-01

    The overall goal of the capsule performance optimization campaign is to maximize the probability of ignition by experimentally correcting for likely residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. This will be accomplished using a variety of targets that will set key laser, hohlraum and capsule parameters to maximize ignition capsule implosion velocity, while minimizing fuel adiabat, core shape asymmetry and ablator-fuel mix. The targets include high Z re-emission spheres setting foot symmetry through foot cone power balance [1], liquid Deuterium-filled ``keyhole'' targets setting shock speed and timing through the laser power profile [2], symmetry capsules setting peak cone power balance and hohlraum length [3], and streaked x-ray backlit imploding capsules setting ablator thickness [4]. We will show how results from successful tuning technique demonstration shots performed at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design meet the required sensitivity and accuracy. We will also present estimates of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors, and show that these get reduced after a number of shots and iterations to meet an acceptable level of residual uncertainty. Finally, we will present results from upcoming tuning technique validation shots performed at NIF at near full-scale. Prepared by LLNL under Contract DE-AC52-07NA27344. [4pt] [1] E. Dewald, et. al. Rev. Sci. Instrum. 79 (2008) 10E903. [0pt] [2] T.R. Boehly, et. al., Phys. Plasmas 16 (2009) 056302. [0pt] [3] G. Kyrala, et. al., BAPS 53 (2008) 247. [0pt] [4] D. Hicks, et. al., BAPS 53 (2008) 2.

  7. Inertial Confinement Fusion quarterly report, January--March 1995. Volume 5, No. 2

    SciTech Connect

    1995-09-01

    The ICF quarterly report is published by the Inertial Confinement Fusion Program at the Lawrence Livermore National Laboratory. Topics included this quarter include: the role of the National Ignition Facility in the development of Inertial Confinement Fusion, laser-plasma interactions in large gas-filled hohlraums, evolution of solid-state induction modulators for a heavy-ion recirculator, the National Ignition Facility project, and terminal-level relaxation in Nd-doped laser material.

  8. 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.

  9. NIF target area design support. Final summary report

    SciTech Connect

    Tokheim, R.E.; Seaman, L.; Curran, D.R.

    1996-02-01

    SRI International continued support work for the National Ignition Facility, Chamber Dynamics Group at Lawrence Livermore National Laboratory (LLNL). The work entailed computational modeling of shrapnel and debris generation from copper shine shields, hohlraum, and stainless steel cryogenic support tubes for 1.8 MJ and 1.0 MJ no-yield and 20 MJ yield shots. Also, the authors addressed the effects of shrapnel at the first wall. Computations for 1.8 MJ showed an ionized gold hohlraum, but about half solid and half ionized copper shine shields, when material cell phase boundaries were maintained. This debris generation represents a potential threat to the first wall and debris shields. Further work is required to translate these results into particle size distributions based on computed strain rates. The authors used simple algorithms for x-ray loading of frost layers protecting the target support to compute peak stress attenuation. They developed algorithmic formulas for predicting damage in candidate first wall materials and they found damage algorithms for fused-silica debris shield material. They obtained very preliminary computational results at 20 MJ for predicting shrapnel mass and particle density at the first wall in spherical polar coordinate space with the hohlraum axis as the polar direction.

  10. LLE Review 117 (October-December 2008)

    SciTech Connect

    Bittle, W., editor

    2009-05-28

    This volume of the LLE Review, covering October-December 2008, features 'Demonstration of the Shock-Timing Technique for Ignition Targets at the National Ignition Facility' by T. R. Boehly, V. N. Goncharov, S. X. Hu, J. A. Marozas, T. C. Sangster, D. D. Meyerhofer (LLE), D. Munro, P. M. Celliers, D. G. Hicks, G. W. Collins, H. F. Robey, O. L. Landen (LLNL), and R. E. Olson (SNL). In this article (p. 1) the authors report on a technique to measure the velocity and timing of shock waves in a capsule contained within hohlraum targets. This technique is critical for optimizing the drive profiles for high-performance inertial-confinement-fusion capsules, which are compressed by multiple precisely timed shock waves. The shock-timing technique was demonstrated on OMEGA using surrogate hohlraum targets heated to 180 eV and fitted with a re-entrant cone and quartz window to facilitate velocity measurements using velocity interferometry. Cryogenic experiments using targets filled with liquid deuterium further demonstrated the entire timing technique in a hohlraum environment. Direct-drive cryogenic targets with multiple spherical shocks were also used to validate this technique, including convergence effects at relevant pressures (velocities) and sizes. These results provide confidence that shock velocity and timing can be measured in NIF ignition targets, thereby optimizing these critical parameters.

  11. Development of our laser fusion integration simulation

    NASA Astrophysics Data System (ADS)

    Li, Jinghong; Zhai, Chuanlei; Li, Shuanggui; Li, Xin; Zheng, Wudi; Yong, Heng; Zeng, Qinghong; Hang, Xudeng; Qi, Jin; Yang, Rong; Cheng, Juan; Song, Peng; Gu, Peijun; Zhang, Aiqing; An, Hengbin; Xu, Xiaowen; Guo, Hong; Cao, Xiaolin; Mo, Zeyao; Pei, Wenbing; Jiang, Song; Zhu, Shao-ping

    2013-11-01

    In the target design of the Inertial Confinement Fusion (ICF) program, it is common practice to apply radiation hydrodynamics code to study the key physical processes happening in ICF process, such as hohlraum physics, radiation drive symmetry, capsule implosion physics in the radiation-drive approach of ICF. Recently, many efforts have been done to develop our 2D integrated simulation capability of laser fusion with a variety of optional physical models and numerical methods. In order to effectively integrate the existing codes and to facilitate the development of new codes, we are developing an object-oriented structured-mesh parallel code-supporting infrastructure, called JASMIN. Based on two-dimensional three-temperature hohlraum physics code LARED-H and two-dimensional multi-group radiative transfer code LARED-R, we develop a new generation two-dimensional laser fusion code under the JASMIN infrastructure, which enable us to simulate the whole process of laser fusion from the laser beams' entrance into the hohlraum to the end of implosion. In this paper, we will give a brief description of our new-generation two-dimensional laser fusion code, named LARED-Integration, especially in its physical models, and present some simulation results of holhraum.

  12. To acquire more detailed radiation drive by use of ``quasi-steady'' approximation in atomic kinetics

    NASA Astrophysics Data System (ADS)

    Ren, Guoli; Pei, Wenbing; Lan, Ke; Gu, Peijun; Li, Xin

    2012-10-01

    In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum- number(n-level) average atom model(AAM) in NLTE plasma description. However, the detailed experimental frequency-dependant radiative drive differs from our n-level simulated drive, which reminds us the need of a more detailed atomic kinetics description. The orbital-quantum- number(nl-level) average atom model is a natural consideration, however the nl-level in-line calculation needs much more computational resource. By distinguishing the rapid bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to build up a more detailed bound electron distribution(nl-level even nlm-level) using in-line n-level calculated plasma conditions(temperature, density, and average ionization degree). We name this method ``quasi-steady approximation'' in atomic kinetics. Using this method, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more fine frequency-denpending spectrum structure which appears only in nl-level transition with same n number(n=0) .

  13. Using radiation temperature to monitor plasma drive in materials strength experiments

    NASA Astrophysics Data System (ADS)

    Benedetti, Laura Robin; Moore, A. S.; Park, H.-S.; Prisbrey, S. T.; Huntington, C. M.; McNaney, J. M.; Smith, R.; Wehrenberg, C. E.; Remington, B. A.; Arsenlis, A.

    2015-11-01

    Materials strength experiments at the National Ignition Facility generate smooth loading in a material by the plasma drive of a shocked reservoir mounted on the side of a gold hohlraum. In these experiments, the loading profile of plasma unloading across a gap and then stagnating at the target is measured with VISAR. Geometric limitations preclude simultaneous measurement of VISAR and the Rayleigh-Taylor (RT) growth that is used to determine strength. We use hohlraum radiation temperatures measured with the Dante spectrometer to link the drive measured with VISAR to the stress condition when RT growth is measured. By combining Dante measurements from two different lines of sight with view factor calculations, we infer the radiation drive into the reservoir. With this method, we can account for spatial variations within the hohlraum and also reproduce observed variations due to changes in pointing and target orientation. We describe the simplified, physics-based analysis of Dante spectra and the methods of determining radiation drive to the reservoir. We then discuss the effectiveness of this method for inferring drive at the target material. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344. LLNL-ABS-674966.

  14. Isoelectronic x-ray spectroscopy to determine electron temperatures in long-scale-length inertial-confinement-fusion plasmas

    NASA Astrophysics Data System (ADS)

    Shepard, T. D.; Back, C. A.; Kalantar, D. H.; Kauffman, R. L.; Keane, C. J.; Klem, D. E.; Lasinski, B. F.; MacGowan, B. J.; Powers, L. V.; Suter, L. J.; Turner, R. E.; Failor, B. H.; Hsing, W. W.

    1996-05-01

    We have successfully employed isoelectronic line ratios to measure the electron temperature in gas-filled Hohlraum targets and gas bags shot with the Nova laser. These targets produce millimeter-scale-length plasmas with electron density Ne~1021 cm-3 and electron temperature Te~3 keV. The Hohlraum targets can also produce radiation temperature exceeding 200 eV. Isoelectronic line ratios are well suited to this measurement because they are relatively insensitive to radiation field effects in Hohlraum targets, opacity, transients, and variations in electron density compared to conventional line ratios. We survey the properties of isoelectronic line ratios formed from ratios of n-to-1 resonance transitions in heliumlike Cr to the same transitions in Ti and compare with conventional ratios of n-to-1 transitions in hydrogenlike Ti to the corresponding transitions in heliumlike Ti, concentrating on plasma parameter ranges of interest to the Nova experiments. We also consider the same ratios using K and Cl. Atomic kinetics are treated using collisional-radiative models and experimental data are analyzed with the aid of radiation-hydrodynamics calculations. When we apply isoelectronic techniques to the Nova experimental data, we find that the targets have electron temperatures of at least 3 keV.

  15. Radiation Transport through cylindrical foams with heated walls

    NASA Astrophysics Data System (ADS)

    Baker, Kevin; MacLaren, Steve; Kallman, Joshua; Heinz, Ken; Hsing, Warren

    2012-10-01

    Radiation transport through low density SiO2 foams has been experimentally studied on the Omega laser. In particular these experiments examined the effects on radiation transport when the boundaries of the SiO2 foam are heated such that energy loss to the boundaries is minimized. The initial density of the SiO2 foams was determined by taking an x-ray radiograph of the foams using a monochromatic Henke source at multiple x-ray energies. The radiation drive used to both study the transport in the SiO2 foam as well as to heat the higher density CRF wall was generated in a laser-heated gold hohlraum using ˜7.5 kJ of the laser energy. The time-dependent spatial profile of the heat wave breaking out of the SiO2 foam was detected with an x-ray streak camera coupled with a soft x-ray transmission grating. The Omega DANTE diagnostic measured the radiation drive in the hohlraum and the Omega VISAR diagnostic monitored the spatial temperature gradient in the foam section of the hohlraum.

  16. 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.

  17. Preconceptual design requirements for the X-1 Advanced Radiation Source

    SciTech Connect

    Rochau, G.E.; Hands, J.A.; Raglin, P.S.; Ramirez, J.J.; Goldstein, S.A.; Cereghino, S.J.; MacLeod, G.

    1998-09-01

    The X-1 Advanced Radiation Source represents the next step in providing the US Department of Energy`s Stockpile Stewardship Program with the high-energy, large volume, laboratory x-ray source for the Radiation Effects Science and Simulation, Inertial Confinement Fusion, and Weapon Physics Programs. Advances in fast pulsed power technology and in z-pinch hohlraums on Sandia National Laboratories` Z Accelerator provide sufficient basis for pursuing the development of X-1. The X-1 plan follows a strategy based on scaling the 2 MJ x-ray output on Z via a 3-fold increase in z-pinch load current. The large volume (>5 cm{sup 3}), high temperature (>150 eV), temporally long (>10 ns) hohlraums are unique outside of underground nuclear weapon testing. Analytical scaling arguments and hydrodynamic simulations indicate that these hohlraums at temperatures of 230--300 eV will ignite thermonuclear fuel and drive the reaction to a yield of 200 to 1,000 MJ in the laboratory. X-1 will provide the high-fidelity experimental capability to certify the survivability and performance of non-nuclear weapon components in hostile radiation environments. Non-ignition sources will provide cold x-ray environments (<15 keV), and high yield fusion burn sources will provide high fidelity warm x-ray environments (15 keV--80 keV).

  18. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic.

    PubMed

    Swadling, G F; Ross, J S; Datte, P; Moody, J; Divol, L; Jones, O; Landen, O

    2016-11-01

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm(-2). This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 10(19) cm(-2) Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

  19. Ignition and Thermonuclear Burn on the National Ignition Facility with Imposed Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Perkins, L. John; Logan, B. G.; Rhodes, M. A.; Zimmerman, G. B.; Ho, D. D.; Blackfield, D. T.; Hawkins, S. A.

    2016-10-01

    We are studying the impact of highly compressed magnetic fields on enhancing the prospects for ignition and burn on the National Ignition Facility (NIF). Both magnetized room-temperature DT gas targets and cryo-ignition capsules are under study. Applied seed fields of 20-70T that compress to greater than 10000T (100MG) under implosion can reduce hotspot conditions required for ignition and propagating burn through range reduction and magnetic mirror trapping of fusion alpha particles, suppression of electron heat conduction and potential stabilization of hydrodynamic instabilities. The applied field may also reduce hohlraum laser-plasma instabilities and suppress the transport of hot electron preheat to the capsule. These combined B-field attributes may permit recovery of ignition, or at least significant alpha particle heating, in capsules that are otherwise submarginal through adverse hydrodynamic or hohlraum-drive conditions. Simulations indicate that optimum initial fields of 50T may produce multi-MJ-yields when applied to our present best experimental capsules. Proof-of-principle experiments for magnetized ignition capsules and hohlraum physics on NIF are now being designed. This work performed under auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  20. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    NASA Astrophysics Data System (ADS)

    Swadling, G. F.; Ross, J. S.; Datte, P.; Moody, J.; Divol, L.; Jones, O.; Landen, O.

    2016-11-01

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ˜8 J cm-2. This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 1019 cm-2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

  1. High-density carbon (HDC) capsule designs for α-heating and for ignition

    NASA Astrophysics Data System (ADS)

    Ho, D.; Amendt, A.; Clark, D.; Haan, S.; Milovich, J.; Salmonson, J.; Zimmerman, G.; Berzak Hopkins, L.; Biener, J.; Meezan, N.; Thomas, C.; Benedict, L.; Le Pape, S.; MacKinnon, A.; Ross, S.

    2014-10-01

    We show capsule designs that have HDC ablators, using 2, 3 and 4 shocks. Their advantages and disadvantages will be discussed. Two-shock designs have the shortest pulse length but have the worst 1-D ignition margin because of the high fuel adiabat. Four-shock designs have the highest 1-D ignition margin with the lowest adiabat, but have higher RT ablation front growth. This disadvantage can be overcome by using a picket to generate the 1st shock. The picket reduces the RT growth factor while the decaying 1st shock lowers the fuel adiabat further. The picket has the additional advantage of shortening the pulse length. Dopant requirements for different hohlraums will be discussed. A 3-shock design for achieving alpha heating is described, which can use either high-gas-fill (1.6 mg/cc) or near-vacuum hohlraums. A rugby-shaped hohlraum with low gas-fill (0.5 mg/cc) has high laser coupling efficiency and provides good symmetry for a 4-shock design. Comparison of simulations for selected recent HDC shots with experimental data will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  2. Theoretical study of symmetry of flux onto a capsule

    NASA Astrophysics Data System (ADS)

    Duan, Hao; Wu, Changshu; Pei, Wenbing; Zou, Shiyang

    2015-09-01

    An analytic model to describe the flux asymmetry onto a capsule based on the viewfactor approximation is developed and verified with numerical simulations. By using a nested spheres technique to represent the various sources of flux asymmetry, the model can treat spherically and cylindrically symmetric hohlraums, e.g., cylinder, elliptic, and rugby. This approach includes the more realistic case of frequency-dependent flux asymmetry compared with the more standard frequency-integrated or single-frequency approaches [D. W. Phillion and S. M. Pollaine, Phys. Plasmas 1, 2963 (1994)]. Correspondingly, the approach can be used to assess x-ray preheat asymmetry generated from localized laser absorption in the high-Z hohlraum wall. For spherical hohlraums with 4, 6, or 8 laser entrance holes (LEHs), an optimal configuration of LEHs, laser spot placement, and angle-of-incidence of the single-ringed laser beams is defined. An analogy between minimizing the flux asymmetry onto a capsule and the Thomson problem of point charge placement on a sphere for minimized energy is shown.

  3. Update on Thermal and Hydrodynamic Simulations on LMJ Cryogenic Targets

    SciTech Connect

    Moll, G.; Charton, S.

    2004-03-15

    The temperature of the cryogenic target inside the hohlraum has been studied with a computational fluid dynamics code (FLUENT). Specific models have been developed and used for both thermal and hydrodynamic calculations.With thermal calculations only, we first have found the optimum heat flux required to counteract the effect of the laser entrance windows. This heat flux is centered on the hohlraum wall along the axis of revolution. With this heat flux, the temperature surface profiles of the capsule and the DT ice layer have been significantly reduced. Second, the sensitivity of the target temperature profiles (capsule and DT layer) relatively to capsule displacement has been determined. Thirdly, the effect of the shield extraction (shield surrounding the cryogenic structure) has been studied and has indicated that the target lifetime before the laser shot is less than 1s. Meanwhile, with hydrodynamic simulations, we have investigated the surface temperature profiles alteration due to He and H{sub 2} mixture convection within the hohlraum.In order to find out the variations between different configurations, results of these studies are given with seven significant digit outputs. Those results only indicate a trend because of the material's properties incertitude and the code approximation.

  4. Observation of hydrodynamic processes of radiation-ablated plasma in a small hole

    SciTech Connect

    Li, Hang; Kuang, Longyu; Jiang, Shaoen Ding, Yongkun; Song, Tianming; Yang, Jiamin Zhu, Tuo; Lin, Zhiwei; Zheng, Jianhua; Zhang, Haiying; Yu, Ruizhen; Liu, Shenye; Hu, Guangyue; Zhao, Bin; Zheng, Jian

    2015-07-15

    In the hohlraum used in laser indirect-drive inertial confinement fusion experiments, hydrodynamic processes of radiation-ablated high-Z plasma have a great effect on laser injection efficiency, radiation uniformity, and diagnosis of hohlraum radiation field from diagnostic windows (DW). To study plasma filling in the DWs, a laser-irradiated Ti disk was used to generate 2–5 keV narrow energy band X-ray as the intense backlighter source, and laser-produced X-ray in a hohlraum with low-Z foam tamper was used to heat a small hole surrounded by gold wall with 150 μm in diameter and 100 μm deep. The hydrodynamic movement of the gold plasma in the small hole was measured by an X-ray framing camera and the results are analyzed. Quantitative measurement of the plasma areal density distribution and evolution in the small hole can be used to assess the effect of plasma filling on the diagnosis from the DWs.

  5. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    SciTech Connect

    Swadling, G. F.; Ross, J. S.; Datte, P.; Moody, J.; Divol, L.; Jones, O.; Landen, O.

    2016-11-15

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

  6. Control of symmetry in Be implosions using a large Case to Capsule ratio

    NASA Astrophysics Data System (ADS)

    Kyrala, George; Kline, J.; Yi, A.; Loomis, E.; Simakov, A.; Wilson, D.; Ralph, J.; Rygg, R.; Strozzi, D.; Ak, G.

    2016-10-01

    (1) Tuning implosion symmetry in indirectly driven spherical capsules has been usually achieved by modifying the inner to outer beam powers inside a hohlraum. This has been done either by changing the wavelength difference between the beams in a gas filled hohlraum leading to cross beam energy transfer between the beams (CBET) , or by varying the inner to outer beam power ratio directly in low-density filled cylindrical hohlraums that permit much lower CBET. Symmetry had shown a large sensitivity to the power ratio of the inner to the outer beam power, partly due to the interaction of the inner beams with the ablated capsule material. To reduce the effect of the capsule ablation on the propagation of the inner laser beams, a larger ratio of the hohraum inner radius to the capsule outer radius has been investigated. This presentation will focus on the results of a series of experiments that monitored the symmetry of the imploding capsule shell as well as the later x-ray emission from the imploded core. We will compare to predictions and post shot calculations.

  7. 2-Shock layered tuning campaign

    NASA Astrophysics Data System (ADS)

    Masse, Laurent; Dittrich, T.; Khan, S.; Kyrala, G.; Ma, T.; MacLaren, S.; Ralph, J.; Salmonson, J.; Tipton, R.; Los Alamos Natl Lab Team; Lawrence Livermore Natl Lab Team

    2016-10-01

    The 2-Shock platform has been developed to maintain shell sphericity throughout the compression phase of an indirect-drive target implosion and produce a stagnating hot spot in a quasi 1D-like manner. A sub-scale, 1700 _m outer diameter, and thick, 200 _m, uniformly Silicon doped, gas-filled plastic capsule is driven inside a nominal size 5750 _m diameter ignition hohlraum. The hohlraum fill is near vacuum to reduce back-scatter and improve laser/drive coupling. A two-shock pulse of about 1 MJ of laser energy drives the capsule. The thick capsule prevents ablation front feed-through to the imploded core. This platform has demonstrated its efficiency to tune a predictable and reproducible 1-D implosion with a nearly round shape. It has been shown that the high foot performance was dominated by the local defect growth due to the ablation front instability and by the hohlraum radiation asymmetries. The idea here is to take advantage of this 2-Shock platform to design a 1D-like layered implosion and eliminates the deleterious effects of radiation asymmetries and ablation front instability growth. We present the design work and our first experimental results of this near one-dimensional 2-Shock layered design. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  8. Re-examining our inhibitions: A speculative re-analysis of data from gold spheres illuminated by the URLLE Omega laser

    NASA Astrophysics Data System (ADS)

    Rosen, Mordecai; Ross, Steven; Thomas, Cliff

    2015-11-01

    A 2006 campaign, that illuminated 1 mm diameter gold spheres using the Omega laser at LLE, required the simulations to use a ``liberal'' flux limiter of f =0.15 (or equivalently a non-local model) in order to match the high levels of measured x-ray emission. In 2013, Thomson Scattering (TS) diagnosed the plasma conditions in the Au sphere's laser heated corona at various radial positions as a function of time. The simulation model using non-local transport compared well for some of the TS data (for ZTe) but not for all of it. Meanwhile, using this model for hohlraums, led to discrepancies with data (such as drive) when applied to some hohlraums, though less-so for others. As a result, hohlraum models with a more restrictive flux limiter, including a ``two-stream-instability (TSI)'' flux limit model (which, when operative, is effectively f =0.015) are being considered. Here we invoke the possibility that the same ion acoustic turbulence (an outgrowth of the TSI), which acts like an effective scatterer to inhibit electron transport, can, by the same token, also increase absorption. This increase in absorption, applied (speculatively) close by the critical surface, can begin to match the Au sphere x-ray emission, as well as a preponderance of the ZTe data. 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. Improving ICF implosion performance with alternative capsule supports

    NASA Astrophysics Data System (ADS)

    Weber, C. R.; Casey, D. T.; Clark, D. S.; Hammel, B. A.; MacPhee, A.; Milovich, J.; Martinez, D.; Robey, H. F.; Smalyuk, V. A.; Stadermann, M.; Amendt, P.; Bhandarkar, S.; Chang, B.; Choate, C.; Crippen, J.; Felker, S. J.; Field, J. E.; Haan, S. W.; Johnson, S.; Kroll, J. J.; Landen, O. L.; Marinak, M.; Mcinnis, M.; Nikroo, A.; Rice, N.; Sepke, S. M.

    2017-05-01

    The thin membrane that holds the capsule in-place in the hohlraum is recognized as one of the most significant contributors to reduced performance in indirect drive inertial confinement fusion (ICF) experiments on the National Ignition Facility. This membrane, known as the "tent," seeds a perturbation that is amplified by Rayleigh-Taylor and can rupture the capsule. A less damaging capsule support mechanism is under development. Possible alternatives include the micron-scale rods spanning the hohlraum width and supporting either the capsule or stiffening the fill-tube, a larger fill-tube to both fill and support the capsule, or a low-density foam layer that protects the capsule from the tent impact. Experiments are testing these support features to measure their imprint on the capsule. These experiments are revealing unexpected aspects about perturbation development in indirect drive ICF, such as the importance of shadows coming from bright spots in the hohlraum. Two dimensional and 3D models are used to explain these features and assess the impact on implosion performance. Experiments and modeling suggest that the fill-tube supported by a perpendicular rod can mount the capsule without any additional perturbation beyond that of the fill tube.

  10. Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis

    SciTech Connect

    Amendt, P.; Colvin, J.; Tipton, R.E.; Hinkel, D.; Edwards, J.J.; Landen, O.I.; Ramshaw, J.D.; Suter, L.J.; Watt, W.G.

    2001-10-15

    The central goal of the National Ignition Facility (NIF) is demonstration of controlled thermonuclear ignition. The mainline ignition target is a low-Z, single-shell cryogenic capsule designed to have weakly nonlinear Rayleigh-Taylor growth of surface perturbations. Double-shell targets are an alternative design concept that avoids the complexity of cryogenic preparation but has greater physics uncertainties associated with performance-degrading mix. A typical double-shell design involves a high-Z inner capsule filled with DT gas and supported within a low-Z ablator shell. The largest source of uncertainty for this target is the degree of highly evolved nonlinear mix on the inner surface of the high-Z shell. High Atwood numbers and feed-through of strong outer surface perturbation growth to the inner surface promote high levels of instability. The main challenge of the double-shell target designs is controlling the resulting nonlinear mix to levels that allow ignition to occur. Design and analysis of a suite of indirect-drive NIF double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. Analysis of these targets includes assessment of two-dimensional radiation asymmetry as well as nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 5, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10-15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser-plasma interactions suggest comparatively benign hohlraum conditions. Application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization

  11. A1.5 Fusion Performance

    SciTech Connect

    Amendt, P

    2011-03-31

    Analysis and radiation hydrodynamics simulations for expected high-gain fusion target performance on a demonstration 1-GWe Laser Inertial Fusion Energy (LIFE) power plant in the mid-2030s timeframe are presented. The required laser energy driver is 2.2 MJ at a 0.351-{micro}m wavelength, and a fusion target gain greater than 60 at a repetition rate of 16 Hz is the design goal for economic and commercial attractiveness. A scaling-law analysis is developed to benchmark the design parameter space for hohlraum-driven central hot-spot ignition. A suite of integrated hohlraum simulations is presented to test the modeling assumptions and provide a basis for a near-term experimental resolution of the key physics uncertainties on the National Ignition Facility (NIF). The NIF is poised to demonstrate ignition by 2012 based on the central hot spot (CHS) mode of ignition and propagating thermonuclear burn [1]. This immediate prospect underscores the imperative and timeliness of advancing inertial fusion as a carbon-free, virtually limitless source of energy by the mid-21st century to substantially offset fossil fuel technologies. To this end, an intensive effort is underway to leverage success at the NIF and to provide the foundations for a prototype 'LIFE.1' engineering test facility by {approx}2025, followed by a commercially viable 'LIFE.2' demonstration power plant operating at 1 GWe by {approx}2035. The current design goal for LIFE.2 is to accommodate {approx}2.2 MJ of laser energy (entering the high-Z radiation enclosure or 'hohlraum') at a 0.351-{micro}m wavelength operating at a repetition rate of 16 Hz and to provide a fusion target yield of 132 MJ. To achieve this design goal first requires a '0-d' analytic gain model that allows convenient exploration of parameter space and target optimization. This step is then followed by 2- and 3-dimensional radiation-hydrodynamics simulations that incorporate laser beam transport, x-ray radiation transport, atomic physics, and

  12. 0.351 micron Laser Beam propagation in High-temperature Plasmas

    SciTech Connect

    Froula, D; Divol, L; Meezan, N; Ross, J; Berger, R L; Michel, P; Dixit, S; Rekow, V; Sorce, C; Moody, J D; Neumayer, P; Pollock, B; Wallace, R; Suter, L; Glenzer, S H

    2007-12-10

    A study of the laser-plasma interaction processes have been performed in plasmas that are created to emulate the plasma conditions in indirect drive inertial confinement fusion targets. The plasma emulator is produced in a gas-filled hohlraum; a blue 351-nm laser beam propagates along the axis of the hohlraum interacting with a high-temperature (T{sub e} = 3.5 keV), dense (n{sub e} = 5 x 10{sup 20}cm{sup -3}), long-scale length (L {approx} 2 mm) plasma. Experiments at these conditions have demonstrated that the interaction beam produces less than 1% total backscatter resulting in transmission greater than 90% for laser intensities less than I < 2 x 10{sup 15} W-cm{sup -2}. The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. A plasma length scaling is also investigated extending our measurements to 4-mm long high-temperature plasmas. At intensities I < 5 x 10{sup 14} W-cm{sup -2}, greater than 80% of the energy in the laser is transmitted through a 5-mm long, high-temperature (T{sub e} > 2.5 keV) high-density (n{sub e} = 5 x 10{sup 20} w-cm{sup -3}) plasma. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows a stimulated Brillouin scattering threshold (R=10%) for a linear gain of 15; these high temperature, low density experiments produce plasma conditions comparable to those along the outer beams in ignition hohlraum designs. By increasing the gas fill density (n{sub e} = 10{sup 21} cm{sup -3}) in these targets, the inner beam ignition hohlraum conditions are

  13. The feed-out process: Rayleigh-Taylor and Richtmyer-Meshkov instabilities in thin, laser-driven foils

    SciTech Connect

    Smitherman, D.P.

    1998-04-01

    Eight beams carrying a shaped pulse from the NOVA laser were focused into a hohlraum with a total energy of about 25 kJ. A planar foil was placed on the side of the hohlraum with perturbations facing away from the hohlraum. All perturbations were 4 {micro}m in amplitude and 50 {micro}m in wavelength. Three foils of pure aluminum were shot with thicknesses and pulse lengths respectively of 86 {micro}m and 2. 2 ns, 50 {micro}m and 4.5 ns, and 35 {micro}m with both 2.2 ns and 4. 5 ns pulses. Two composite foils constructed respectively of 32 and 84 {micro}m aluminum on the ablative side and 10 {micro}m beryllium on the cold surface were also shot using the 2.2 ns pulse. X-ray framing cameras recorded perturbation growth using both face- and side-on radiography. The LASNEX code was used to model the experiments. A shock wave interacted with the perturbation on the cold surface generating growth from a Richtmyer-Meshkov instability and a strong acoustic mode. The cold surface perturbation fed-out to the Rayleigh-Taylor unstable ablation surface, both by differential acceleration and interface coupling, where it grew. A density jump did not appear to have a large effect on feed-out from interface coupling. The Rayleigh-Taylor instability`s vortex pairs overtook and reversed the direction of flow of the Richtmyer-Meshkov vortices, resulting in the foil moving from a sinuous to a bubble and spike configuration. The Rayleigh-Taylor instability may have acted as an ablative instability on the hot surface, and as a classical instability on the cold surface, on which grew second and third order harmonics.

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

    SciTech Connect

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

    2016-05-15

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

  15. Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures less than 1 keV

    SciTech Connect

    Ross, James Steven

    2010-01-01

    Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (Te < 1 keV). These effects have been observed experimentally and agree well with a relativistic treatment of the Thomson scattering form factor [2]. The results are important for the interpretation of scattering measurements from laser produced plasmas. Thomson scattering measurements are used to characterize the hydrodynamics of a gas jet plasma which is the foundation for a broad series of laser-plasma interaction studies [3, 4, 5, 6]. The temporal evolution of the electron temperature, density and ion temperature are measured. The measured electron density evolution shows excellent agreement with a simple adiabatic expansion model. The effects of high temperatures on coupling to hohlraum targets is discussed [7]. A peak electron temperature of 12 keV at a density of 4.7 × 1020cm-3 are measured 200 μm outside the laser entrance hole using a two-color Thomson scattering method we developed in gas jet plasmas [8]. These measurements are used to assess laser-plasma interactions that reduce laser hohlraum coupling and can significantly reduce the hohlraum radiation temperature.

  16. Progress in Target Physics and Design for Heavy Ion Fusion

    NASA Astrophysics Data System (ADS)

    Callahan-Miller, Debra

    1999-11-01

    Two-dimensional, integrated calculations of a close-coupled version of the distributed radiator, heavy ion target predict gain 130 from 3.3 MJ of beam energy. To achieve these results, the case-to-capsule ratio was decreased by about 25% from our previous targets.(M. Tabak, D. Callahan-Miller, Phys. Plasmas, 5, 1895 (1998).) The smaller hohlraum results in smaller beam spots than had been previously assumed; this puts renewed emphasis on controlling emittance growth in the accelerator and on space-charge neutralization in the reactor chamber. These targets are robust--changes in ion range and ion stopping model can be accommodated by changes in the target. Single-mode Rayleigh-Taylor growth rates for this capsule are smaller than those for at least one NIF design. As a result, stability issues for the heavy ion capsule can be settled on NIF. The close-coupled target also opens up the possibility of a high gain Engineering Test Facility from a 1.5-2 MJ driver; calculations predict that gain 90 is achievable from 1.75 MJ of beam energy. Gain curves, used for optimizing the system of accelerator, final focus, chamber transport, and target, are in good agreement with the two-dimensional calculations for both the ``conventional'' and close-coupled case-to-capsule ratio. Finally, we will discuss the choice of hohlraum wall material which must satisfy constraints from target physics (high opacity/low heat capacity to minimize the amount of energy in the hohlraum wall), environment and safety (low activation for recycling and waste disposal), chamber design (recovery of the material from the chamber), and target fabrication (need to produce many low cost targets per day).

  17. High-resolution, detailed simulations of low foot and high foot implosion experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Clark, Daniel

    2015-11-01

    In order to achieve the several hundred Gbar stagnation pressures necessary for inertial confinement fusion ignition, implosion experiments on the National Ignition Facility (NIF) require the compression of deuterium-tritium fuel layers by a convergence ratio as high as forty. Such high convergence implosions are subject to degradation by a range of perturbations, including the growth of small-scale defects due to hydrodynamic instabilities, as well as longer scale modulations due to radiation flux asymmetries in the enclosing hohlraum. Due to the broad range of scales involved, and also the genuinely three-dimensional (3-D) character of the flow, accurately modeling NIF implosions remains at the edge of current radiation hydrodynamics simulation capabilities. This talk describes the current state of progress of 3-D, high-resolution, capsule-only simulations of NIF implosions aimed at accurately describing the performance of specific NIF experiments. Current simulations include the effects of hohlraum radiation asymmetries, capsule surface defects, the capsule support tent and fill tube, and use a grid resolution shown to be converged in companion two-dimensional simulations. The results of detailed simulations of low foot implosions from the National Ignition Campaign are contrasted against results for more recent high foot implosions. While the simulations suggest that low foot performance was dominated by ablation front instability growth, especially the defect seeded by the capsule support tent, high foot implosions appear to be dominated by hohlraum flux asymmetries, although the support tent still plays a significant role. Most importantly, it is found that a single, standard simulation methodology appears adequate to model both implosion types and gives confidence that such a model can be used to guide future implosion designs toward ignition. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  19. Interferometric adaptive optics for the National Ignition Facility

    SciTech Connect

    Baker, Kevin

    2010-06-02

    Great strides have been made during the past half century in pursuit of fusion energy as a relatively clean and essentially unlimited energy source. One of two current approaches, inertial-confinement fusion (ICF), uses a large number of lasers to either directly compress a capsule containing deuterium and tritium (DT) or indirectly convert the laser photons into x-rays on the wall of a Hohlraum (an idealized cavity) and use this radiation to compress a DT-filled capsule. The latter, indirect-drive ICF is currently being pursued by the newly commissioned National Ignition Facility (NIF).

  20. L-Shell Spectroscopy of Au as a Temperature Diagnostic Tool

    SciTech Connect

    Trabert, E; Hansen, S B; Beiersdorfer, P; Brown, G V; Widmann, K; Chung, H K

    2008-03-27

    In order to develop plasma diagnostic for reduced-size hot hohlraums under laser irradiation, they have studied the L-shell emission from highly charged gold ions in the SuperEBIT electron beam ion trap. The resolving power necessary to identify emission features from individual charge states in a picket fence pattern has been estimated, and the observed radiation features have been compared with atomic structure calculations. They find that the strong 3d{sub 5/2} {yields} 2p{sub 3/2} emission features are particularly useful in determining the charge state distribution and average ion charge , which are strongly sensitive to the electron temperature.

  1. NIF Ignition Target 3D Point Design

    SciTech Connect

    Jones, O; Marinak, M; Milovich, J; Callahan, D

    2008-11-05

    We have developed an input file for running 3D NIF hohlraums that is optimized such that it can be run in 1-2 days on parallel computers. We have incorporated increasing levels of automation into the 3D input file: (1) Configuration controlled input files; (2) Common file for 2D and 3D, different types of capsules (symcap, etc.); and (3) Can obtain target dimensions, laser pulse, and diagnostics settings automatically from NIF Campaign Management Tool. Using 3D Hydra calculations to investigate different problems: (1) Intrinsic 3D asymmetry; (2) Tolerance to nonideal 3D effects (e.g. laser power balance, pointing errors); and (3) Synthetic diagnostics.

  2. Determination of relative krypton fission product yields from 14 MeV neutron induced fission of (238)U at the National Ignition Facility.

    PubMed

    Edwards, E R; Cassata, W S; Velsko, C A; Yeamans, C B; Shaughnessy, D A

    2016-11-01

    Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of (88)Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the (85m)Kr/(88)Kr ratio, which may be the result of incorrect nuclear data.

  3. LLE Review 120 (July-September 2009)

    SciTech Connect

    Edgell, D.H., editor

    2001-02-19

    This issue has the following articles: (1) The Omega Laser Facility Users Group Workshop; (2) The Effect of Condensates and Inner Coatings on the Performance of Vacuum Hohlraum Targets; (3) Zirconia-Coated-Carbonyl-Iron-Particle-Based Magnetorheological Fluid for Polishing Optical Glasses and Ceramics; (4) All-Fiber Optical Magnetic Field Sensor Based on Faraday Rotation in Highly Terbium Doped Fiber; (5) Femtosecond Optical Pump-Probe Characterization of High-Pressure-Grown Al{sub 0.86}Ga{sub 0.14}N Single Crystals; (6) LLE's Summer High School Research Program; (7) Laser Facility Report; and (8) National Laser Users Facility and External Users Programs.

  4. Recent advances in indirect drive ICF target physics at LLNL

    SciTech Connect

    Bernat, T P; Collins, G W; Haan, S; Hammel, B A; Landen, O L; MacGowan, B J; Sutter, L J

    1998-01-13

    In preparation for ignition on the National Ignition Facility, the Lawrence Livermore National Laboratory's Inertial Confinement Fusion Program, working in collaboration with Los Alamos National Laboratory, Commissariat a 1'Energie Atomique (CEA), and Laboratory for Laser Energetics at the University of Rochester, has performed a broad range of experiments on the Nova and Omega lasers to test the fundamentals of the NIF target designs. These studies have refined our understanding of the important target physics, and have led to many of the specifications for the NIF laser and the cryogenic ignition targets. Our recent work has been focused in the areas of hohlraum energetics, symmetry, shock physics, and target design optimization & fabrication.

  5. The Path to Ignition on NIF

    NASA Astrophysics Data System (ADS)

    Lindl, John

    2005-10-01

    Advances in ignition target designs, including both indirect and direct drive schemes, have opened up a significantly larger and more robust operating space for ignition on NIF. The point design for our 2010 ignition experiments relies on indirect drive, and uses beryllium capsules with copper doped in a radially varying concentration. In simulations, these targets tolerate surface roughness several times the best previous target designs. The target will utilize a small fill-tube to introduce DT into the Be capsule. Be capsules absorb about 30% more energy in a given hohlraum than a CH capsule. The hohlraums for the 2010 experiments include several design modifications to increase efficiency. Mixtures of high-z materials (cocktails) can ``fill holes'' in the x-ray opacity and result in reduced losses into the hohlraum wall. Laser entrance hole (LEH)shields, which block the view of the LEH as seen by the capsule, increase the energy absorbed by the capsule. These advances increase the ignition margin on NIF by almost a factor of two. With significant advances in target fabrication technology, most requirements for the ignition targets have now been demonstrated. When all 192 beams of NIF are available for precision experiments in 2010, we will conduct an ignition campaign to obtain the required hohlraum drive, to tune symmetry, to optimize ablator performance for ablation depth and stability, and to adjust shock timing prior to the first ignition attempts. Polar Direct Drive is also being developed for ignition on NIF. In this scheme, the arrangement of the NIF beams developed for Indirect Drive is utilized for Direct Drive by employing a combination of re-pointing, phase-plate design, and target geometry. Recent experiments on the Omega laser at LLE have demonstrated an ability to control symmetry using these techniques. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405

  6. Nova symmetry: Experiments, modeling, and interpretation (HLP3 and HLP4)

    SciTech Connect

    Suter, L.J.; Hauer, A.A.; Powers, L.V.

    1996-06-01

    Understanding and controlling capsule implosion symmetry is a key requirement for inertial confinement fusion (ICF). Symmetry was specifically called out in the Nova Technical Contract (NTC) as the HLP4 task. Later, elements of HLP3 were expanded to include symmetry work. For nearly a decade and a half it has been recognized that the fundamental asymmetry in a laser-heated hohlraum is a long-wavelength pole-waist radiation flux variation that varies like the P{sub 2} Legendre polynomial. It has also been recognized that one can control this asymmetry and achieve nearly symmetric implosions by appropriately pointing the laser beams.

  7. Backscatter measurements for NIF ignition targets (invited).

    PubMed

    Moody, J D; Datte, P; Krauter, K; Bond, E; Michel, P A; Glenzer, S H; Divol, L; Niemann, C; Suter, L; Meezan, N; MacGowan, B J; Hibbard, R; London, R; Kilkenny, J; Wallace, R; Kline, J L; Knittel, K; Frieders, G; Golick, B; Ross, G; Widmann, K; Jackson, J; Vernon, S; Clancy, T

    2010-10-01

    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ∼15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  8. Update of Environmental and Safety Analyses for the National Ignition Facility: Using a New Model to Track Target Material Usage

    SciTech Connect

    Gillich, D; Tobin, M; Singh, M; Kalantar, D; Brereton, S; MacGowan, B

    2001-08-03

    The purpose of this paper is to report the methodology and assumptions, data, and results of calculations concerning safety and environmental issues related to excursions to currently planned NIF operations. Many possible uses of NIF have been suggested over the years. While some of these possible uses have been adopted into the baseline plans for NIF, many others have not. While we do not yet know all of the possible approved uses for NIF, one of the items that would bear on whether a certain course use might be adopted or not would be its environmental and safety impact. Here we examine certain excursions from the existing planned operations to determine their environmental and safety impacts. These excursions are related to the use of ''cocktail'' hohlraums as the baseline target for ignition experiments in the National Ignition Facility (NIF) as well as possible increased utilization of beryllium and uranium. This paper also addresses the fission products produced from cocktail hohlraum use for high yield experiments. Again, this analyses does not imply an authorization to proceed with such modes of operation, or any intent to proceed beyond this analyses. A detailed analysis of a range of postulated experiments for NIF was conducted for the years 2003 through 2011. The goal was to quantify the amount of target material introduced into the target bay per year. The assumptions outlined in this paper are based on the worst-case scenario from an environmental perspective. A spreadsheet was developed to integrate all the gathered information and to calculate the total amount of materials per year. The spreadsheet was also designed as a tool for future analyses. The total amount of material was used to justify and establish a proposed upper bound for the amount of beryllium and uranium introduced into the target bay in a given year. The cocktail hohlraum and associated appendages were modeled with the neutron transport code TART98 to determine neutron fluxes within

  9. Investigating radial wire array Z pinches as a compact x-ray source on the Saturn generator

    DOE PAGES

    Ampleford, David J.; Bland, S. N.; Jennings, Christopher A.; ...

    2015-08-27

    Radial wire array z pinches, where wires are positioned radially outward from a central cathode to a concentric anode, can act as a compact bright x-ray source that could potentially be used to drive a hohlraum. Experiments were performed on the 7-MA Saturn generator using radial wire arrays. These experiments studied a number of potential risks in scaling radial wire arrays up from the 1-MA level, where they have been shown to be a promising compact X-ray source. Data indicates that at 7 MA, radial wire arrays can radiate ~9 TW with 10-ns full-width at half-maximum from a compact pinch.

  10. Recent Advances in Indirect Drive ICF Target Physics

    SciTech Connect

    Hammel, B; Lindl, J; Amendt, P A; Bernat, G W; Collins, G W; Glenzer, S H; Koch, S H; Haan, S; Landen, O L; Suter, L J

    2002-10-08

    In preparation for ignition on the National Ignition Facility, the Lawrence Livermore National Laboratory's Inertial Confinement Fusion Program, working in collaboration with Los Alamos National Laboratory, Commissariat a lEnergie Atomique (CEA), and Laboratory for Laser Energetics at the University of Rochester, has performed a broad range of experiments on the Nova and Omega lasers to test the fundamentals of the NIF target designs. These studies have refined our understanding of the important target physics, and have led to many of the specifications for the NIF laser and the cryogenic ignition targets. Our recent work has been focused in the areas of hohlraum energetics, symmetry, shock physics, and target design optimization & fabrication.

  11. Review of high convergence implosion experiments with single and double shell targets

    SciTech Connect

    Delamater, N. D.; Watt, R. G.; Varnum, W. S.

    2002-01-01

    Experiments have been been performed in recent years at the Omega laser studying double shell capsules as an a1 teinative, 11011 cryogenic, path towards ignition at NTF. Double shell capsules designed to mitigate the Au M-band radiation asymmetries, were experimentally found to perform well in both spherical and cylindrical hohlraums, achieving near 1-D (-90 %) clean calculated yield at convergence comparable to that required for NIF ignition. Near-term plans include directly driven double shell experiments at Omega, which eliminates Au M-band radiation as a yield degradation m ec h an i s in.

  12. Development of Thomson scattering system on Shenguang-III prototype laser facility.

    PubMed

    Gong, Tao; Li, Zhichao; Jiang, Xiaohua; Ding, Yongkun; Yang, Dong; Wang, Zhebin; Wang, Fang; Li, Ping; Hu, Guangyue; Zhao, Bin; Liu, Shenye; Jiang, Shaoen; Zheng, Jian

    2015-02-01

    A Thomson scattering diagnostic system, using a 263 nm laser as the probe beam, is designed and implemented on Shenguang-III prototype laser facility. The probe beam is provided by an additional beam line completed recently. The diagnostic system allows simultaneous measurements of both ion feature and red-shifted electron feature from plasmas in a high-temperature (≥2 keV) and high-density (≥10(21) cm(-3)) regime. Delicate design is made to satisfy the requirements for successful detection of the electron feature. High-quality ion feature spectra have already been diagnosed via this system in recent experiments with gas-filled hohlraums.

  13. Interaction of soft-x-ray thermal radiation with foam-layered targets.

    PubMed

    Batani, D; Desai, T; Löwer, Th; Hall, T A; Nazarov, W; Koenig, M; Benuzzi-Mounaix, A

    2002-06-01

    We have studied the interaction of soft-x-ray thermal radiation with foam-layered metal targets. X-ray radiation was produced by focusing a high-energy laser inside a small size hohlraum. An increment in shock pressure, up to a factor of approximately 4 for 50 mg/cm(3) foam density, was observed with the foam layer as compared to bare metal targets. This follows from the propagation of radiation-driven shock wave in the foam and the impedance mismatch at the foam-payload interface.

  14. Hohraum-driven non-cryogenic double-shell ignition target designs for the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Amendt, Peter

    2001-10-01

    The central goal of the National Ignition Facility (NIF) is demonstration of controlled thermonuclear ignition. The mainline ignition target is a low-Z, single-shell cryogenic capsule designed to have weakly nonlinear Rayleigh-Taylor growth of surface perturbations. Double-shell targets are an alternative design concept which avoids the considerable complexity of cryogenic preparation but has greater physics uncertainties associated with performance-degrading mix. A typical double-shell design involves a high-Z inner capsule filled with DT gas and supported within a low-Z ablator shell. The largest source of uncertainty for this target is the degree of highly evolved nonlinear mix on the inner surface of the high-Z shell. High Atwood numbers and feedthrough of strong outer surface perturbation growth to the inner surface promote high levels of instability. The main challenge of the double-shell target designs is controlling the resulting nonlinear mix to levels that allow ignition to occur. We present design and analysis of a suite of indirectly-driven NIF double-shell targets spanning hohlraum temperatures from 200eV to 300eV. Our analysis of these targets includes assessment of nonlinear mix as well as two-dimensional radiation asymmetry. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [1]. These simulations also reveal a new need to diagnose and control localized L-shell emission from the high-Z hohlraum wall because of strong x-ray absorption by the high-Z inner shell. Analysis with a variety of nonlinear mix models, including subgrid turbulence and buoyancy-drag models [2,3], and multimode simulations indicate a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. In collaboration with J. Colvin, G. Dimonte, J.E. Edwards, J.D. Ramshaw, L.J. Suter, R. Tipton and W. Varnum. [1] L

  15. Backscatter measurements for NIF ignition targets (invited)

    SciTech Connect

    Moody, J. D.; Datte, P.; Krauter, K.; Bond, E.; Michel, P. A.; Glenzer, S. H.; Divol, L.; Suter, L.; Meezan, N.; MacGowan, B. J.; Hibbard, R.; London, R.; Kilkenny, J.; Wallace, R.; Knittel, K.; Frieders, G.; Golick, B.; Ross, G.; Widmann, K.; Jackson, J.; and others

    2010-10-15

    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of {approx}15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  16. Backscatter measurements for NIF ignition targets (invited)

    SciTech Connect

    Moody, J. D.; Datte, P.; Krauter, K.; Bond, E.; Michel, P. A.; Glenzer, S. H.; Divol, L.; Niemann, C.; Suter, L.; Meezan, N.; MacGowan, B. J.; Hibbard, R.; London, R.; Kilkenny, J.; Wallace, R.; Kline, J. L.; Knittel, K.; Frieders, G.; Golick, B.; Ross, G.; Widmann, K.; Jackson, J.; Vernon, S.; Clancy, T.

    2010-10-26

    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ~15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  17. Raman Backscatter as a Remote Laser Power Sensor in High-Energy-Density Plasmas [Stimulated Scattering as a Remote Laser Power Sensor in High-Density and Temperature Plasmas

    DOE PAGES

    Moody, J. D.; Strozzi, D. J.; Divol, L.; ...

    2013-07-09

    Stimulated Raman backscatter is used as a remote sensor to quantify the instantaneous laser power after transfer from outer to inner cones that cross in a National Ignition Facility (NIF) gas-filled hohlraum plasma. By matching stimulated Raman backscatter between a shot reducing outer versus a shot reducing inner power we infer that about half of the incident outer-cone power is transferred to inner cones, for the specific time and wavelength configuration studied. Furthermore, this is the first instantaneous nondisruptive measure of power transfer in an indirect drive NIF experiment using optical measurements.

  18. Deep Dive Topic: State of understanding of capsule modeling in context of high-foot

    SciTech Connect

    Hurricane, O. A.; Clark, D. S.

    2015-07-14

    The work is summarized from several perspectives: 1D simulation perspective: Post-shot models agree with yield data to within a factor of ~2 at low implosion velocities, but the models diverge from the data as the velocity and convergence ratio increase. 2D simulation perspective: Integrated hohlraum-capsule post-shot models agree with primary data for most implosions, but overpredict yield and DSR for a few of the highest velocity implosions. High-resolution 3D post-shot capsule-only modeling captures much of the delivered performance of the one shot currently simulated.

  19. Determination of relative krypton fission product yields from 14 MeV neutron induced fission of 238U at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Edwards, E. R.; Cassata, W. S.; Velsko, C. A.; Yeamans, C. B.; Shaughnessy, D. A.

    2016-11-01

    Precisely-known fission yield distributions are needed to determine a fissioning isotope and the incident neutron energy in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility induce fission in depleted uranium contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, and 89) are measured relative to the cumulative yield of 88Kr and compared to previously tabulated values. The results from this experiment and England and Rider are in agreement, except for the 85mKr/88Kr ratio, which may be the result of incorrect nuclear data.

  20. Characteristic measurements of silicon dioxide aerogel plasmas generated in a Planckian radiation environment

    SciTech Connect

    Dong Quanli; Wang Shoujun; Li Yutong; Zhang Yi; Zhao Jing; Wei Huigang; Shi Jianrong; Zhao Gang; Zhang Jiyan; Gu Yuqiu; Ding Yongkun; Wen Tianshu; Zhang Wenhai; Hu Xin; Liu Shenye; Zhang Lin; Tang Yongjian; Zhang Baohan; Zheng Zhijian; Nishimura, Hiroaki

    2010-01-15

    The temporally and spatially resolved characteristics of silicon dioxide aerogel plasmas were studied using x-ray spectroscopy. The plasma was generated in the near-Planckian radiation environment within gold hohlraum targets irradiated by laser pulses with a total energy of 2.4 kJ in 1 ns. The contributions of silicon ions at different charge states to the specific components of the measured absorption spectra were also investigated. It was found that each main feature in the absorption spectra of the measured silicon dioxide aerogel plasmas was contributed by two neighboring silicon ionic species.