162 results on '"David N. Fittinghoff"'
Search Results
2. Yield and PDV Measurements of the Godiva-IV Critical Assembly
- Author
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R A Buckles, D. Bower, Mark May, J Scorby, M Pena, L. Snyder, David N. Fittinghoff, and J Goda
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Yield (engineering) ,Materials science ,Analytical chemistry - Published
- 2021
3. Observation of Hydrodynamic Flows in Imploding Fusion Plasmas on the National Ignition Facility
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Mark Eckart, Laura Robin Benedetti, Shahab Khan, J. D. Kilkenny, Leonard Jarrott, Brian Spears, David Schlossberg, J. E. Field, Christopher Young, Ryan Nora, M. Gatu Johnson, Daniel Casey, A. J. Mackinnon, W. W. Hsing, E. P. Hartouni, A. S. Moore, Robert Hatarik, D. H. Munro, Otto Landen, Sabrina Nagel, P. K. Patel, B. J. MacGowan, David N. Fittinghoff, Petr Volegov, R. M. Bionta, Arthur Pak, Gary Grim, B. Bachmann, K. D. Meaney, and V. Geppert-Kleinrath
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Physics ,Jet (fluid) ,General Physics and Astronomy ,Mechanics ,Laser ,Neutron spectroscopy ,law.invention ,Physics::Fluid Dynamics ,law ,Neutron ,National Ignition Facility ,Anisotropy ,Inertial confinement fusion ,Doppler broadening - Abstract
Inertial confinement fusion implosions designed to have minimal fluid motion at peak compression often show significant linear flows in the laboratory, attributable per simulations to percent-level imbalances in the laser drive illumination symmetry. We present experimental results which intentionally varied the mode 1 drive imbalance by up to 4% to test hydrodynamic predictions of flows and the resultant imploded core asymmetries and performance, as measured by a combination of DT neutron spectroscopy and high-resolution x-ray core imaging. Neutron yields decrease by up to 50%, and anisotropic neutron Doppler broadening increases by 20%, in agreement with simulations. Furthermore, a tracer jet from the capsule fill-tube perturbation that is entrained by the hot-spot flow confirms the average flow speeds deduced from neutron spectroscopy.
- Published
- 2021
4. Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using a cylindrical-harmonics expansion
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Christopher Danly, Steven H. Batha, V. Geppert-Kleinrath, Carl Wilde, Alex Zylstra, Petr Volegov, and David N. Fittinghoff
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010302 applied physics ,Physics ,Cylindrical harmonics ,Thermonuclear fusion ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,Implosion ,01 natural sciences ,010305 fluids & plasmas ,Computational physics ,Physics::Plasma Physics ,0103 physical sciences ,Neutron source ,Neutron ,National Ignition Facility ,Instrumentation ,Inertial confinement fusion - Abstract
Inertial confinement fusion capsule implosions produce neutron, gamma-ray, and x-ray emission, which are recorded by a variety of detectors, both time integrated and time resolved, to determine the performance of the implosion. Two-dimensional emission images from multiple directions can now be combined to infer three-dimensional structures in the implosion, such as the distribution of thermonuclear fuel density, carbon ablator, and impurities. Because of the cost and complexity of the imaging systems, however, only a few measurements can be made, so reconstructions of the source must be made from a limited number of views. Here, a cylindrical-harmonics decomposition technique to reconstruct the three-dimensional object from two views in the same symmetry plane is presented. In the limit of zero order, this method recovers the Abel inversion method. The detailed algorithms used for this characterization and the resulting reconstructed neutron source from an experiment collected at the National Ignition Facility are presented.
- Published
- 2021
5. Bootstrap estimation of the effect of instrument response function uncertainty on the reconstruction of fusion neutron sources
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Kevin M. Lamb, Verena Geppert-Kleinrath, Noah W. Birge, Christopher R. Danly, Laurent Divol, David N. Fittinghoff, Matthew S. Freeman, Arthur E. Pak, Carl H. Wilde, Alex B. Zylstra, and Petr L. Volegov
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Instrumentation - Abstract
Neutron imagers are important diagnostics for the inertial confinement fusion implosions at the National Ignition Facility. They provide two- and three-dimensional reconstructions of the neutron source shape that are key indicators of the overall performance. To interpret the shape results properly, it is critical to estimate the uncertainty in those reconstructions. There are two main sources of uncertainties: limited neutron statistics, leading to random errors in the reconstructed images, and incomplete knowledge of the instrument response function (the pinhole-dependent point spread function). While the statistical errors dominate the uncertainty for lower yield deuterium-tritium (DT) shots, errors due to the instrument response function dominate the uncertainty for DT yields on the order of 1016 neutrons or higher. In this work, a bootstrapping method estimates the uncertainty in a reconstructed image due to the incomplete knowledge of the instrument response function. The main reconstruction is created from the fixed collection of pinhole images that are best aligned with the neutron source. Additional reconstructions are then built using subsets of that collection of images. Variations in the shapes of these additional reconstructions originate solely from uncertainties in the instrument response function, allowing us to use them to provide an additional systematic uncertainty estimate.
- Published
- 2022
6. Time-Resolved Fuel Density Profiles of the Stagnation Phase of Indirect-Drive Inertial Confinement Implosions
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Otto Landen, M. Hamamoto, T. Kohut, M. Schoff, W. W. Hsing, R. Sigurdsson, Jeremy Kroll, S. L. Ayers, R. J. Wallace, David N. Fittinghoff, Daniel H. Kalantar, S. Herriot, Gareth Hall, M. P. Mauldin, J. M. Di Nicola, Nobuhiko Izumi, Mark W. Bowers, D. K. Bradley, D. Homoelle, David Martinez, S. A. Vonhof, D. R. Hargrove, David Alessi, J. K. Okui, Riccardo Tommasini, Laurent Divol, T. Zobrist, A. Conder, Andreas Kemp, Matthew A. Prantil, K. Youngblood, John E. Heebner, Suhas Bhandarkar, Mark R. Hermann, P. Di Nicola, R. Lowe-Webb, J. Park, Jose Milovich, Janice K. Lawson, G. Gururangan, Paul J. Wegner, J. P. Holder, S. P. Hatchett, E. P. Hartouni, D. M. Holunga, K. N. LaFortune, M. J. Edwards, A. Nikroo, Mark Herrmann, C. F. Walters, N. D. Masters, Carlos A. Iglesias, L. Pelz, C. C. Widmayer, Wade H. Williams, L. F. Berzak Hopkins, Petr Volegov, and A. J. Mackinnon
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Materials science ,Phase (waves) ,General Physics and Astronomy ,Implosion ,Hot spot (veterinary medicine) ,Mechanics ,Kinetic energy ,Residual ,01 natural sciences ,Sphericity ,Physics::Plasma Physics ,0103 physical sciences ,010306 general physics ,National Ignition Facility ,Inertial confinement fusion - Abstract
The implosion efficiency in inertial confinement fusion depends on the degree of stagnated fuel compression, density uniformity, sphericity, and minimum residual kinetic energy achieved. Compton scattering-mediated 50-200 keV x-ray radiographs of indirect-drive cryogenic implosions at the National Ignition Facility capture the dynamic evolution of the fuel as it goes through peak compression, revealing low-mode 3D nonuniformities and thicker fuel with lower peak density than simulated. By differencing two radiographs taken at different times during the same implosion, we also measure the residual kinetic energy not transferred to the hot spot and quantify its impact on the implosion performance.
- Published
- 2020
7. Impact of Localized Radiative Loss on Inertial Confinement Fusion Implosions
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E. L. Dewald, Carl Wilde, Daniel S. Clark, P. K. Patel, Tammy Ma, Andrew MacPhee, Alastair Moore, C. R. Weber, Louisa Pickworth, E. Marley, Petr Volegov, V. Geppert-Kleinrath, Omar Hurricane, Arthur Pak, Matthias Hohenberger, Derek Mariscal, S. Le Pape, David N. Fittinghoff, Laurent Divol, and L. F. Berzak Hopkins
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Thermonuclear fusion ,Materials science ,General Physics and Astronomy ,Hot spot (veterinary medicine) ,Plasma ,Fusion power ,01 natural sciences ,Deuterium ,Physics::Plasma Physics ,0103 physical sciences ,Radiative transfer ,Neutron ,Atomic physics ,010306 general physics ,Inertial confinement fusion - Abstract
The impact to fusion energy production due to the radiative loss from a localized mix in inertial confinement implosions using high density carbon capsule targets has been quantified. The radiative loss from the localized mix and local cooling of the reacting plasma conditions was quantified using neutron and x-ray images to reconstruct the hot spot conditions during thermonuclear burn. Such localized features arise from ablator material that is injected into the hot spot from the Rayleigh-Taylor growth of capsule surface perturbations, particularly the tube used to fill the capsule with deuterium and tritium fuel. Observations, consistent with analytic estimates, show the degradation to fusion energy production to be linearly proportional to the fraction of the total emission that is associated with injected ablator material and that this radiative loss has been the primary source of variations, of up to 1.6 times, in observed fusion energy production. Reducing the fill tube diameter has increased the ignition metric ${\ensuremath{\chi}}_{\mathrm{no}\text{ }\ensuremath{\alpha}}$ from 0.49 to 0.72, 92% of that required to achieve a burning hot spot.
- Published
- 2020
8. MHD-240 Neutron Detection Efficiency and Sensitivity Calibration
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L. Snyder, David N. Fittinghoff, D. Bower, and Mark May
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Physics ,Optics ,business.industry ,Calibration ,Neutron detection ,Sensitivity (control systems) ,Magnetohydrodynamics ,business - Published
- 2020
9. Density determination of the thermonuclear fuel region in inertial confinement fusion implosions
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Frank E. Merrill, Steven H. Batha, K. McGlinchey, Doug Wilson, David N. Fittinghoff, Petr Volegov, Jeremy Chittenden, Christopher Danly, Brian Appelbe, Daniel Casey, Aidan Crilly, Carl Wilde, V. Geppert-Kleinrath, Engineering & Physical Science Research Council (EPSRC), Lawrence Livermore National Laboratory, and AWE Plc
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Thermonuclear fusion ,Nuclear Theory ,Inelastic collision ,General Physics and Astronomy ,Implosion ,02 engineering and technology ,01 natural sciences ,09 Engineering ,Physics, Applied ,Physics::Plasma Physics ,0103 physical sciences ,Nuclear fusion ,Neutron ,Nuclear Experiment ,Inertial confinement fusion ,01 Mathematical Sciences ,Applied Physics ,010302 applied physics ,Physics ,Science & Technology ,02 Physical Sciences ,Neutron imaging ,Detector ,021001 nanoscience & nanotechnology ,Computational physics ,Physical Sciences ,0210 nano-technology - Abstract
Understanding of the thermonuclear burn in an inertial confinement fusion implosion requires knowledge of the local deuterium–tritium (DT) fuel density. Neutron imaging of the core now provides this previously unavailable information. Two types of neutron images are required. The first is an image of the primary 14-MeV neutrons produced by the D + T fusion reaction. The second is an image of the 14-MeV neutrons that leave the implosion hot spot and are downscattered to lower energy by elastic and inelastic collisions in the fuel. These neutrons are measured by gating the detector to record the 6–12 MeV neutrons. Using the reconstructed primary image as a nonuniform source, a set of linear equations is derived that describes the contribution of each voxel of the DT fuel region to a pixel in the downscattered image. Using the measured intensity of the 14-MeV neutrons and downscattered images, the set of equations is solved for the density distribution in the fuel region. The method is validated against test problems and simulations of high-yield implosions. The calculated DT density distribution from one experiment is presented.Understanding of the thermonuclear burn in an inertial confinement fusion implosion requires knowledge of the local deuterium–tritium (DT) fuel density. Neutron imaging of the core now provides this previously unavailable information. Two types of neutron images are required. The first is an image of the primary 14-MeV neutrons produced by the D + T fusion reaction. The second is an image of the 14-MeV neutrons that leave the implosion hot spot and are downscattered to lower energy by elastic and inelastic collisions in the fuel. These neutrons are measured by gating the detector to record the 6–12 MeV neutrons. Using the reconstructed primary image as a nonuniform source, a set of linear equations is derived that describes the contribution of each voxel of the DT fuel region to a pixel in the downscattered image. Using the measured intensity of the 14-MeV neutrons and downscattered images, the set of equat...
- Published
- 2020
10. Three-dimensional diagnostics and measurements of inertial confinement fusion plasmas
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R. M. Bionta, K. D. Hahn, E. P. Hartouni, Daniel Casey, V. Geppert-Kleinrath, David Schlossberg, Shaun Kerr, Alastair Moore, Mark Eckart, Gary Grim, J. Jeet, David N. Fittinghoff, A. J. Mackinnon, and Petr Volegov
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010302 applied physics ,Physics ,Drift velocity ,media_common.quotation_subject ,Implosion ,Plasma ,01 natural sciences ,Asymmetry ,010305 fluids & plasmas ,Computational physics ,0103 physical sciences ,Electron temperature ,Neutron ,National Ignition Facility ,Instrumentation ,Inertial confinement fusion ,media_common - Abstract
Recent inertial confinement fusion measurements have highlighted the importance of 3D asymmetry effects on implosion performance. One prominent example is the bulk drift velocity of the deuterium–tritium plasma undergoing fusion (“hotspot”), vHS. Upgrades to the National Ignition Facility neutron time-of-flight diagnostics now provide vHS to better than 1 part in 104 and enable cross correlations with other measurements. This work presents the impact of vHS on the neutron yield, downscatter ratio, apparent ion temperature, electron temperature, and 2D x-ray emission. The necessary improvements to diagnostic suites to take these measurements are also detailed. The benefits of using cross-diagnostic analysis to test hotspot models and theory are discussed, and cross-shot trends are shown.
- Published
- 2021
11. Hotspot parameter scaling with velocity and yield for high-adiabat layered implosions at the National Ignition Facility
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Ryan Nora, Marius Millot, C. R. Weber, Daniel Casey, Peter M. Celliers, Nobuhiko Izumi, R. M. Bionta, A. L. Kritcher, Robert Hatarik, Benjamin Bachmann, Tammy Ma, D. T. Woods, Clement Goyon, Omar Hurricane, K. D. Meaney, C. Wilde, S. Khan, Kevin Baker, David Strozzi, George A. Kyrala, C. B. Yeamans, Jose Milovich, Matthias Hohenberger, Otto Landen, David N. Fittinghoff, David Turnbull, David C. Clark, M. Gatu Johnson, Laura Robin Benedetti, Debra Callahan, Sabrina Nagel, C. A. Thomas, Richard Berger, Brian Spears, P. K. Patel, and Petr Volegov
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Physics ,Fusion ,Extrapolation ,Implosion ,Mechanics ,01 natural sciences ,Power law ,010305 fluids & plasmas ,law.invention ,Ignition system ,Physics::Plasma Physics ,law ,0103 physical sciences ,Hotspot (geology) ,010306 general physics ,National Ignition Facility ,Scaling - Abstract
This paper presents a study on hotspot parameters in indirect-drive, inertially confined fusion implosions as they proceed through the self-heating regime. The implosions with increasing nuclear yield reach the burning-plasma regime, hotspot ignition, and finally propagating burn and ignition. These implosions span a wide range of alpha heating from a yield amplification of 1.7-2.5. We show that the hotspot parameters are explicitly dependent on both yield and velocity and that by fitting to both of these quantities the hotspot parameters can be fit with a single power law in velocity. The yield scaling also enables the hotspot parameters extrapolation to higher yields. This is important as various degradation mechanisms can occur on a given implosion at fixed implosion velocity which can have a large impact on both yield and the hotspot parameters. The yield scaling also enables the experimental dependence of the hotspot parameters on yield amplification to be determined. The implosions reported have resulted in the highest yield (1.73×10^{16}±2.6%), yield amplification, pressure, and implosion velocity yet reported at the National Ignition Facility.
- Published
- 2019
12. Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility
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Brent Manley Jones, B. R. McWatters, David N. Fittinghoff, Gary Wayne Cooper, J. D. Styron, Chimpén Ruiz, D. J. Ampleford, Kelly Hahn, Gordon A. Chandler, Andrew Maurer, Jose A. Torres, Mark May, and J. D. Vaughan
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Physics ,Point spread function ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Magnetized Liner Inertial Fusion ,Fusion power ,01 natural sciences ,010305 fluids & plasmas ,Optics ,0103 physical sciences ,Neutron source ,Neutron ,010306 general physics ,business ,Instrumentation ,Image resolution ,Inertial confinement fusion - Abstract
The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 μm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-μm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 1012 deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 μm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-μm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 1012 deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron r...
- Published
- 2018
13. Three dimensional low-mode areal-density non-uniformities in indirect-drive implosions at the National Ignition Facility
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J. L. Peterson, J. E. Field, David Schlossberg, D. H. Munro, B. J. MacGowan, Michael Kruse, David N. Fittinghoff, Alex Zylstra, V. A. Smalyuk, Daniel Casey, E. P. Hartouni, Jose Milovich, A. L. Kritcher, Christopher Young, A. S. Moore, R. M. Bionta, Carl Wilde, K. D. Hahn, Brian Spears, V. Geppert-Kleinrath, Johan Frenje, Jim Gaffney, Kelli Humbird, Omar Hurricane, Maria Gatu-Johnson, Ryan Nora, Daniel S. Clark, Debra Callahan, Petr Volegov, and Otto Landen
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Physics ,Coupling ,Neutron transport ,media_common.quotation_subject ,Shell (structure) ,Implosion ,Condensed Matter Physics ,Kinetic energy ,01 natural sciences ,Asymmetry ,010305 fluids & plasmas ,Computational physics ,0103 physical sciences ,010306 general physics ,National Ignition Facility ,Inertial confinement fusion ,media_common - Abstract
To achieve hotspot ignition, an inertial confinement fusion implosion must achieve high hotspot pressure that is inertially confined by a dense shell of DT fuel. This requires a symmetric implosion having high in-flight shell velocity and high areal density at stagnation. The size of the driver and scale of the capsule required can be minimized by maintaining a high efficiency of energy coupling from the imploding shell to the hotspot. Significant 3D low mode asymmetries, however, are commonly observed in indirect-drive implosions and reduce the coupling of shell kinetic energy to the hotspot. To better quantify the magnitudes and impacts of shell density asymmetries, we have developed new analysis techniques and analytic models [Hurricane et al., Phys. Plasmas 27(6), 062704 (2020)]. To build confidence in the underlying data, we have also developed an analytic neutron transport model to cross-compare two independent measurements of asymmetry, which shows excellent agreement across shots for mode-1 (l = 1). This work also demonstrates that asymmetry can introduce potential sampling bias into down-scattered ratio measurements causing the solid-angle-average and uncertainty-weighted-average down-scattered ratios to differ significantly. Diagnosing asymmetries beyond mode-1 (l > 1) presents significant challenges. Using new diagnostic instruments and analysis techniques, however, evidence of significant Legendre mode P2 (l = 2, m = 0) and additional 3D asymmetries (l > 1, m ≠ 0) are beginning to emerge from the high precision activation diagnostic data (real-time nuclear activation detectors) and down-scattered neutron imaging data.
- Published
- 2021
14. Fuel convergence sensitivity in indirect drive implosions
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Omar Hurricane, K. D. Meaney, Peter M. Celliers, B. J. MacGowan, N. Gharibyan, Marius Millot, S. W. Haan, Jose Milovich, Steve MacLaren, J. D. Lindl, P. T. Springer, E. P. Hartouni, Gary Grim, V. N. Goncharov, David N. Fittinghoff, P. K. Patel, M. J. Edwards, Daniel Casey, Petr Volegov, H. S. Robey, and Otto Landen
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Physics ,Implosion ,Mechanics ,Condensed Matter Physics ,01 natural sciences ,Aspect ratio (image) ,010305 fluids & plasmas ,Shock (mechanics) ,law.invention ,Ignition system ,Physics::Plasma Physics ,law ,0103 physical sciences ,Compressibility ,010306 general physics ,National Ignition Facility ,Scaling ,Inertial confinement fusion - Abstract
In inertial confinement fusion experiments at the National Ignition Facility, a spherical shell of deuterium–tritium fuel is imploded in an attempt to reach the conditions needed for fusion, self-heating, and eventual ignition. Since theory and simulations indicate that ignition efficacy in 1D improves with increasing imploded fuel convergence ratio, it is useful to understand the sensitivity of the scale-invariant fuel convergence on all measurable or inferable 1D parameters. In this paper, we develop a simple isobaric and isentropic compression scaling model incorporating sensitivity to the in-flight adiabat inferred from shock strengths, to measured implosion velocity, and to known initial ablator and fuel aspect ratio and mass ratio. The model is first benchmarked to 1D implosion simulations spanning a variety of relevant implosion designs. We then use the model to compare compressibility trends across all existing indirect-drive layered implosion data from the facility spanning three ablators [CH, carbon (C), and Be], for which in-flight fuel adiabats varied from 1.6 to 5 by varying the number of drive shocks from 2 to 4, peak implosion velocities varied by 1.4×, capsule radii by 50%, and initial fuel aspect ratios by 1.4×. We find that the strength of the first shock is the dominant contributor setting the maximum fuel convergence. We also observe additional sensitivities to successive shock strengths and fuel aspect ratios that improve the agreement between the expected and measured compression for carbon and Be designs with adiabats above 3. A principal finding is that the adiabat 2.5 C-shell designs exhibit less convergence than CH-shell designs of similar inferred in-flight adiabat.
- Published
- 2021
15. Enhanced direct-drive implosion performance on NIF with wavelength separation
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Hans W. Herrmann, P. B. Radha, P. W. McKenty, Alex Zylstra, M. Hoppe, C. B. Yeamans, S. Le Pape, Matthias Hohenberger, R. S. Craxton, David N. Fittinghoff, Yong Ho Kim, and A. J. Mackinnon
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Physics ,Energy transfer ,Implosion ,Energy coupling ,Condensed Matter Physics ,01 natural sciences ,Symmetry (physics) ,010305 fluids & plasmas ,law.invention ,Ignition system ,Wavelength ,law ,Yield (chemistry) ,0103 physical sciences ,Calibration ,Atomic physics ,010306 general physics - Abstract
Cross-beam energy transfer (CBET) can significantly affect the energy coupling and symmetry of direct-drive implosions. We report on a series of direct-drive shots with 2.1 mm outer diameter capsules conducted on NIF for diagnostic development and calibration in which the wavelength separation ( Δ λ) between the inner and outer cone beams was varied. We observe a strong improvement in performance as Δ λ is applied, with the nuclear yield increasing by up to a factor of 4 ×. Other data including the nuclear bang time and implosion symmetry suggest that increasing Δ λ suppresses CBET and improves both the energy coupling and drive symmetry. These results provide a strong and important benchmark for CBET models applicable to direct-drive ignition designs.
- Published
- 2020
16. Experiments to explore the influence of pulse shaping at the National Ignition Facility
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Laura Robin Benedetti, Shahab Khan, George A. Kyrala, Max Tabak, Gary Grim, Sabrina Nagel, Nobuhiko Izumi, R. M. Bionta, E. M. Campbell, Ryan Nora, S. M. Finnegan, Marius Millot, D. T. Woods, David N. Fittinghoff, Kevin Baker, David J. Clark, Richard Berger, P. K. Patel, David Strozzi, T. Ma, Petr Volegov, A. Nikroo, M. Gatu Johnson, Benjamin Bachmann, Cliff Thomas, D. T. Casey, C. B. Yeamans, Matthias Hohenberger, Darwin Ho, A. L. Kritcher, Brian Spears, Jose Milovich, Robert Hatarik, and Peter M. Celliers
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Physics ,media_common.quotation_subject ,Nuclear engineering ,Plasma ,Condensed Matter Physics ,Inertia ,Laser ,Pulse shaping ,Pulse (physics) ,law.invention ,Physics::Plasma Physics ,law ,Compressibility ,Area density ,National Ignition Facility ,media_common - Abstract
The shaping of the drive pulse in time is a key tool in the design of fusion experiments that use inertia to confine burning plasmas. It is directly related to the adiabat and compressibility of the DT fuel and the characteristics of the laser and target that are needed to ignite. With this in mind, we have performed experiments at the National Ignition Facility that test small changes in the shape of the pulse. In contrast to theory, we find implosions at lower adiabats can have reduced yield and areal density. We discuss implications to performance and the mechanism(s) that could be responsible.
- Published
- 2020
17. Fill tube dynamics in inertial confinement fusion implosions with high density carbon ablators
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C. Kong, C. R. Weber, Daniel Casey, M. Schneider, J. Crippen, Alastair Moore, P. K. Patel, Shahab Khan, J. D. Moody, Peter Amendt, Debra Callahan, N. Alfonso, Omar Hurricane, C. A. Thomas, David N. Fittinghoff, Petr Volegov, Nathan Meezan, Brian Spears, Kevin Baker, Jose Milovich, Alex Zylstra, T. R. Dittrich, Otto Landen, D. T. Woods, C. B. Yeamans, Arthur Pak, and George A. Kyrala
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Thermal equilibrium ,Physics ,Active galactic nucleus ,Astrophysics::High Energy Astrophysical Phenomena ,Plasma ,Mechanics ,Condensed Matter Physics ,01 natural sciences ,Flattening ,010305 fluids & plasmas ,Astron ,Physics::Plasma Physics ,Drag ,0103 physical sciences ,Hotspot (geology) ,010306 general physics ,Inertial confinement fusion - Abstract
Plasma jets, such as γ-ray burst jets, Herbig–Haro jets, μ-quasar jets, and active galactic nuclei jets, are found throughout the universe [S. Mendoza et al., Rev. Mex. Astron. Astrofis. 41, 453 (2005)]. Plasma jets are also present in indirect drive inertial confinement fusion experiments originating from the capsule's fill tube and occasionally from divots and voids in the capsules, particles on the exterior of the capsule, or from the tent holding the capsule in the target. This paper looks at two different gas-filled capsule implosions containing a plasma jet resulting from a capsule fill tube and fill channel, both of which utilized high density carbon ablators. Two models were developed, a drag and a snowplow model, which use the time-dependent motion of the injected mass through the hotspot to estimate the mass injected into the hotspot from the fill tube and channel, arriving at an average injected mass of ∼84.5 ± 25.5 ng for the first experiment and 91 ± 20 ng for the second experiment. Unlike previous methods to estimate fill tube injected mass, these techniques do not assume that the mixed mass is in thermal equilibrium with the hotspot or that the x-ray emission is only coming from within the hotspot itself. This paper also discusses the features seen in these experiments which include limb brightening in the shell for undoped ablators and flattening in the ablator from shadowing by the fill tube.
- Published
- 2020
18. Deficiencies in compression and yield in x-ray-driven implosions
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Benjamin Bachmann, A. L. Kritcher, M. Gatu Johnson, Peter M. Celliers, Sabrina Nagel, Tammy Ma, Jose Milovich, David Strozzi, C. B. Yeamans, Matthias Hohenberger, G. A. Kyrala, S. M. Finnegan, Max Tabak, E. M. Campbell, David N. Fittinghoff, Kevin Baker, C. A. Thomas, Nobuhiko Izumi, R. M. Bionta, Daniel Casey, Laura Robin Benedetti, Brian Spears, Shahab Khan, Robert Hatarik, Richard Berger, P. K. Patel, A. Nikroo, Gary Grim, Marius Millot, D. T. Woods, Darwin Ho, Petr Volegov, Ryan Nora, and David C. Clark
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Physics ,Fusion ,Yield (engineering) ,Nuclear engineering ,Internal pressure ,Ion temperature ,Condensed Matter Physics ,Compression (physics) ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Ignition system ,Physics::Plasma Physics ,Hohlraum ,law ,0103 physical sciences ,Area density ,010306 general physics - Abstract
This paper analyzes x-ray-driven implosions that are designed to be less sensitive to 2D and 3D effects in Hohlraum and capsule physics. Key performance metrics including the burn-averaged ion temperature, hot-spot areal density, and fusion yield are found to agree with simulations where the design adiabat (internal pressure) is multiplied by a factor of 1.4. These results motivate the development of a simple model for interpreting experimental data, which is then used to quantify how improvements in compression could help achieve ignition.
- Published
- 2020
19. Principal factors in performance of indirect-drive laser fusion experiments
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David C. Clark, M. Gatu Johnson, E. M. Campbell, Petr Volegov, Richard Berger, G. A. Kyrala, P. K. Patel, Gary Grim, Robert Hatarik, David N. Fittinghoff, C. B. Yeamans, Sabrina Nagel, Ryan Nora, Matthias Hohenberger, Peter M. Celliers, Daniel Casey, Marius Millot, Max Tabak, D. T. Woods, Darwin Ho, Benjamin Bachmann, A. L. Kritcher, Brian Spears, Laura Robin Benedetti, A. Nikroo, Jose Milovich, Tammy Ma, Shahab Khan, S. M. Finnegan, C. A. Thomas, David Strozzi, Kevin Baker, Nobuhiko Izumi, and R. M. Bionta
- Subjects
Physics ,Fusion ,Scale (ratio) ,Implosion ,Condensed Matter Physics ,Laser ,01 natural sciences ,Symmetry (physics) ,010305 fluids & plasmas ,Computational physics ,law.invention ,Pulse (physics) ,law ,0103 physical sciences ,010306 general physics ,Inertial confinement fusion ,Energy (signal processing) - Abstract
Progress in inertial confinement fusion depends on the accurate interpretation of experiments that are complex and difficult to explain with simulations. Results could depend on small changes in the laser pulse or target or physics that are not fully understood or characterized. In this paper, we discuss an x-ray-driven platform [Baker et al., Phys. Rev. Lett. 121, 135001 (2018)] with fewer sources of degradation and find the fusion yield can be described as a physically motivated function of laser energy, target scale, and implosion symmetry. This platform and analysis could enable a more experimental approach to the study and optimization of implosion physics.
- Published
- 2020
20. Inertially confined fusion plasmas dominated by alpha-particle self-heating
- Author
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E. J. Bond, Petr Volegov, C. B. Yeamans, Matthias Hohenberger, T. G. Parham, C. J. Cerjan, Andrea Kritcher, Klaus Widmann, J. D. Moody, Frank E. Merrill, D. H. Edgell, John Kline, Joseph Ralph, E. L. Dewald, Otto Landen, B. J. Kozioziemski, T. R. Dittrich, J. E. Field, Rebecca Dylla-Spears, Abbas Nikroo, Daniel Casey, Felicie Albert, J. A. Caggiano, Andrew MacPhee, S. W. Haan, Denise Hinkel, Jason Ross, D. Shaughnessy, Ryan Rygg, Pierre Michel, L. F. Berzak Hopkins, D. Hoover, P. K. Patel, Marilyn Schneider, Jose Milovich, Laura Robin Benedetti, Richard Town, Shahab Khan, M. A. Barrios Garcia, D. A. Callahan, P. T. Springer, T. Kohut, T. Ma, S. R. Nagel, Alan S. Wan, Jay D. Salmonson, J. P. Knauer, G. A. Kyrala, Brian Spears, A. V. Hamza, Harry Robey, Robert Hatarik, Hans W. Herrmann, S. Le Pape, David N. Fittinghoff, D. K. Bradley, Daniel Sayre, Nobuhiko Izumi, R. M. Bionta, Johan Frenje, Gary Grim, H.-S. Park, Omar Hurricane, David Strozzi, M. Gatu Johnson, Carl Wilde, M. J. Edwards, Tilo Döppner, Art Pak, J. A. Church, David Turnbull, R. Tommasini, Alastair Moore, O. S. Jones, and Peter M. Celliers
- Subjects
Physics ,Fusion plasma ,General Physics and Astronomy ,Plasma ,Alpha particle ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Ignition system ,Nuclear physics ,Physics::Plasma Physics ,law ,0103 physical sciences ,Nuclear fusion ,010306 general physics ,Self heating ,Inertial confinement fusion - Abstract
Inertial confinement fusion, based on laser-heating a deuterium–tritium mixture, is one of the approaches towards energy production from fusion reactions. Now, record energy-yield experiments are reported—bringing us closer to ignition conditions.
- Published
- 2016
21. Hotspot conditions achieved in inertial confinement fusion experiments on the National Ignition Facility
- Author
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J. E. Field, Brian Spears, C. R. Weber, Daniel Casey, O. S. Jones, N. Izumi, P. K. Patel, Kelli Humbird, E. L. Dewald, Jay D. Salmonson, Andrew MacPhee, A. L. Kritcher, Tammy Ma, Steve MacLaren, V. Geppert-Kleinrath, C. J. Cerjan, Leonard Jarrott, E. P. Hartouni, V. A. Smalyuk, Alex Zylstra, Jose Milovich, Laurent Divol, P. T. Springer, Joseph Ralph, Jim Gaffney, Otto Landen, Petr Volegov, L. F. Berzak Hopkins, Ryan Nora, S. Le Pape, David N. Fittinghoff, C. A. Thomas, Denise Hinkel, Michael Kruse, B. Bachmann, Omar Hurricane, Matthias Hohenberger, Shahab Khan, Nathan Meezan, Laurent Masse, J. L. Peterson, Robert Hatarik, Daniel S. Clark, Debra Callahan, Gary Grim, Kevin Baker, Harry Robey, M. J. Edwards, Tilo Döppner, and Arthur Pak
- Subjects
Physics ,Nuclear engineering ,Observable ,Condensed Matter Physics ,law.invention ,Ignition system ,Physics::Plasma Physics ,law ,Hotspot (geology) ,Isobaric process ,Area density ,Overall performance ,Physics::Chemical Physics ,National Ignition Facility ,Inertial confinement fusion - Abstract
We describe the overall performance of the major indirect-drive inertial confinement fusion campaigns executed at the National Ignition Facility. With respect to the proximity to ignition, we can describe the performance of current experiments both in terms of no-burn ignition metrics (metrics based on the hydrodynamic performance of targets in the absence of alpha-particle heating) and in terms of the thermodynamic properties of the hotspot and dense fuel at stagnation—in particular, the hotspot pressure, temperature, and areal density. We describe a simple 1D isobaric model to derive these quantities from experimental observables and examine where current experiments lie with respect to the conditions required for ignition.
- Published
- 2020
22. Evolution of the neutron imaging aperture
- Author
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John A. Oertel, V. E. Fatherley, H. J. Jorgenson, V. Geppert-Kleinrath, C. Wilde, Derek Schmidt, Gary Grim, David N. Fittinghoff, and Petr Volegov
- Subjects
Physics ,Optics ,business.industry ,Aperture ,Neutron imaging ,business - Published
- 2018
23. Fusion Energy Output Greater than the Kinetic Energy of an Imploding Shell at the National Ignition Facility
- Author
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S. R. Nagel, L. F. Berzak Hopkins, D. A. Callahan, E. L. Dewald, Petr Volegov, T. Ma, Suhas Bhandarkar, D. H. Edgell, S. Le Pape, Pierre Michel, Nobuhiko Izumi, Jose Milovich, P. K. Patel, B. J. MacGowan, Darwin Ho, C. B. Yeamans, M. Havre, Laurent Divol, David N. Fittinghoff, Maria Gatu-Johnson, Shahab Khan, Joseph Ralph, Nathan Meezan, C. Wild, G. A. Kyrala, A. Nikroo, Michael Stadermann, J. Crippen, Jason Ross, A. J. Mackinnon, S. W. Haan, Omar Hurricane, David Strozzi, L. R. Bennedetti, Clement Goyon, Robert Hatarik, T. Bunn, J. Jaquez, Andrew MacPhee, Jürgen Biener, Marius Millot, Neal Rice, C. R. Weber, Daniel Casey, and Art Pak
- Subjects
Materials science ,General Physics and Astronomy ,chemistry.chemical_element ,Fusion power ,Kinetic energy ,01 natural sciences ,010305 fluids & plasmas ,chemistry ,Hohlraum ,0103 physical sciences ,Radiative transfer ,Area density ,Atomic physics ,010306 general physics ,National Ignition Facility ,Stagnation pressure ,Helium - Abstract
A series of cryogenic, layered deuterium-tritium (DT) implosions have produced, for the first time, fusion energy output twice the peak kinetic energy of the imploding shell. These experiments at the National Ignition Facility utilized high density carbon ablators with a three-shock laser pulse (1.5 MJ in 7.5 ns) to irradiate low gas-filled (0.3 mg/cc of helium) bare depleted uranium hohlraums, resulting in a peak hohlraum radiative temperature ∼290 eV. The imploding shell, composed of the nonablated high density carbon and the DT cryogenic layer, is, thus, driven to velocity on the order of 380 km/s resulting in a peak kinetic energy of ∼21 kJ, which once stagnated produced a total DT neutron yield of 1.9×10^{16} (shot N170827) corresponding to an output fusion energy of 54 kJ. Time dependent low mode asymmetries that limited further progress of implosions have now been controlled, leading to an increased compression of the hot spot. It resulted in hot spot areal density (ρr∼0.3 g/cm^{2}) and stagnation pressure (∼360 Gbar) never before achieved in a laboratory experiment.
- Published
- 2018
24. Potential Improvements for the One-Dimensional Imager of Neutrons at the Sandia Z Facility
- Author
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C. Wilde, Jeremy Vaughan, David N. Fittinghoff, Mark May, Chimpén Ruiz, Petr Volegov, and D. J. Ampleford
- Subjects
Nuclear engineering ,Neutron - Published
- 2018
25. System design of the NIF Neutron Imaging System North Pole
- Author
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Derek Schmidt, M. J. Ayers, Hans W. Herrmann, Frank E. Merrill, John A. Oertel, M. A. Vitalich, D. A. Barker, Lynne Goodwin, N. Shingleton, David N. Fittinghoff, R. L. Hibbard, C. Wilde, H. J. Jorgenson, Steven H. Batha, Gary Grim, J. I. Martinez, Petr Volegov, Christopher Danly, and V. E. Fatherley
- Subjects
North pole ,Physics ,business.industry ,Neutron imaging ,01 natural sciences ,010305 fluids & plasmas ,Metrology ,Optics ,Physics::Plasma Physics ,0103 physical sciences ,Systems design ,Neutron ,010306 general physics ,National Ignition Facility ,business ,Inertial confinement fusion - Abstract
A new neutron imager, known as Neutron Imaging System North Pole, has been fielded to image the neutrons produced in the burn region of imploding fusion capsules at the National Ignition Facility. The resolution and alignment requirements and parameters that drive the design of this system are similar to the pre-existing equatorial system, there are significant changes. This work describes the parameters and limitations driving the design of this system, discusses the metrology and alignment, and shows some data from the instrument.
- Published
- 2017
26. Fluence-compensated down-scattered neutron imaging using the neutron imaging system at the National Ignition Facility
- Author
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David N. Fittinghoff, Brian Spears, V. A. Smalyuk, D. H. Munro, Otto Landen, Petr Volegov, J. E. Field, Frank E. Merrill, Daniel Casey, and Gary Grim
- Subjects
Physics ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Nuclear Theory ,Neutron scattering ,01 natural sciences ,Neutron time-of-flight scattering ,Neutron temperature ,010305 fluids & plasmas ,Nuclear physics ,Optics ,Neutron flux ,0103 physical sciences ,Neutron cross section ,Neutron source ,Neutron detection ,Nuclear Experiment ,010306 general physics ,business ,Instrumentation - Abstract
The Neutron Imaging System at the National Ignition Facility is used to observe the primary ∼14 MeV neutrons from the hotspot and down-scattered neutrons (6-12 MeV) from the assembled shell. Due to the strong spatial dependence of the primary neutron fluence through the dense shell, the down-scattered image is convolved with the primary-neutron fluence much like a backlighter profile. Using a characteristic scattering angle assumption, we estimate the primary neutron fluence and compensate the down-scattered image, which reveals information about asymmetry that is otherwise difficult to extract without invoking complicated models.
- Published
- 2016
27. Progress of indirect drive inertial confinement fusion in the United States
- Author
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D. Hoover, John Kline, J. A. Caggiano, D. H. Edgell, Omar Hurricane, Alex Zylstra, David Strozzi, Rebecca Dylla-Spears, J. E. Field, Michael Farrell, Laurent Divol, Andrew MacPhee, E. Piceno, O. S. Jones, Tammy Ma, C. Kong, E. J. Bond, Darwin Ho, Steven H. Batha, Steve MacLaren, E. L. Dewald, Sebastien LePape, S. Khan, James Ross, Daniel Sayre, Robert Tipton, Monika M. Biener, B. Cagadas, Jay D. Salmonson, C. F. Walters, S. A. Johnson, David N. Fittinghoff, A. Nikroo, Harry Robey, Ep. Hartouni, D. K. Bradley, H. Huang, Laurent Masse, Petr Volegov, Michael Stadermann, Hans W. Herrmann, Jürgen Biener, S. W. Haan, Don Bennett, Rpj Town, S. M. Sepke, James McNaney, C. J. Cerjan, Kevin Henderson, R. M. Bionta, V. A. Smalyuk, Nathan Meezan, N. Izumi, M. Schneider, M.R. Sacks, Louisa Pickworth, Brian Haines, Jose Milovich, A. V. Hamza, W. W. Hsing, J. D. Kilkenny, E. Woerner, P. K. Patel, Mark Eckart, Laura Robin Benedetti, B. E. Yoxall, Carlos E. Castro, J. D. Moody, J. D. Sater, B. J. Kozioziemski, M. Gatu Johnson, A. J. Mackinnon, Brian Spears, R. Seugling, David C. Clark, Robert Hatarik, Jeremy Kroll, S. A. Yi, Denise Hinkel, Cliff Thomas, Joseph Ralph, M. Wang, Otto Landen, T. Braun, J.F. Merrill, C. B. Yeamans, Matthias Hohenberger, M. Schoff, Carl Wilde, Larry L. Peterson, M. J. Edwards, Tilo Döppner, Gary Grim, J. R. Rygg, Arthur Pak, George A. Kyrala, Suhas Bhandarkar, Wolfgang Stoeffl, Debra Callahan, Neal Rice, M. Hoppe, and L. F. Berzak Hopkins
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Condensed Matter Physics ,Inertial confinement fusion - Abstract
Indirect drive converts high power laser light into x-rays using small high-Z cavities called hohlraums. X-rays generated at the hohlraum walls drive a capsule filled with deuterium–tritium (DT) fuel to fusion conditions. Recent experiments have produced fusion yields exceeding 50 kJ where alpha heating provides ~3× increase in yield over PdV work. Closing the gaps toward ignition is challenging, requiring optimization of the target/implosions and the laser to extract maximum energy. The US program has a three-pronged approach to maximize target performance, each closing some portion of the gap. The first item is optimizing the hohlraum to couple more energy to the capsule while maintaining symmetry control. Novel hohlraum designs are being pursued that enable a larger capsule to be driven symmetrically to both reduce 3D effects and increase energy coupled to the capsule. The second issue being addressed is capsule stability. Seeding of instabilities by the hardware used to mount the capsule and fill it with DT fuel remains a concern. Work reducing the impact of the DT fill tubes and novel capsule mounts is being pursed to reduce the effect of mix on the capsule implosions. There is also growing evidence native capsule seeds such as a micro-structure may be playing a role on limiting capsule performance and dedicated experiments are being developed to better understand the phenomenon. The last area of emphasis is the laser. As technology progresses and understanding of laser damage/mitigation advances, increasing the laser energy seems possible. This would increase the amount of energy available to couple to the capsule, and allow larger capsules, potentially increasing the hot spot pressure and confinement time. The combination of each of these focus areas has the potential to produce conditions to initiate thermo-nuclear ignition.
- Published
- 2019
28. Toward a burning plasma state using diamond ablator inertially confined fusion (ICF) implosions on the National Ignition Facility (NIF)
- Author
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P. A. Sterne, J. Jaquez, A. L. Kritcher, Tammy Ma, Jürgen Biener, E. L. Dewald, C. R. Weber, Michael Stadermann, Daniel Casey, J. Crippen, N. Meezan, O. S. Jones, Andrew MacPhee, Laurent Divol, Sebastien LePape, James Ross, A. J. Mackinnon, Laura Robin Benedetti, T. Bunn, Darwin Ho, Richard Town, George A. Kyrala, Suhas Bhandarkar, S. Khan, N. Izumi, David C. Clark, S. M. Sepke, Harry Robey, Arthur Pak, L. F. Berzak Hopkins, M. J. Edwards, B. J. MacGowan, V. A. Smalyuk, Marius Millot, C. Kong, Neal Rice, Maria Gatu-Johnson, Robert Hatarik, Jose Milovich, Debra Callahan, D. H. Edgell, Sabrina Nagel, Christoph Wild, Petr Volegov, Clement Goyon, Denise Hinkel, Omar Hurricane, C. B. Yeamans, M. Havre, David Strozzi, Joseph Ralph, Otto Landen, H. Huang, A. Nikroo, Alastair Moore, David N. Fittinghoff, Pierre Michel, M. M. Marinak, P. K. Patel, and S. W. Haan
- Subjects
Fusion ,Materials science ,Nuclear engineering ,Diamond ,Plasma ,engineering.material ,Condensed Matter Physics ,Laser ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Nuclear Energy and Engineering ,law ,Hohlraum ,0103 physical sciences ,engineering ,010306 general physics ,National Ignition Facility ,Inertial confinement fusion - Published
- 2018
29. Design of the aperture array for neutron imaging from the north pole of the National Ignition Facility
- Author
-
D. A. Barker, Frank E. Merrill, Derek Schmidt, Petr Volegov, Carl Wilde, V. E. Fatherley, David N. Fittinghoff, John A. Oertel, R. L. Hibbard, and J. I. Martinez
- Subjects
010302 applied physics ,Physics ,Aperture array ,Aperture ,business.industry ,Neutron imaging ,Resolution (electron density) ,Astrophysics::Instrumentation and Methods for Astrophysics ,01 natural sciences ,010305 fluids & plasmas ,Metrology ,Optics ,Physics::Plasma Physics ,0103 physical sciences ,Neutron ,Pinhole (optics) ,business ,National Ignition Facility - Abstract
A new neutron imager, known as Neutron Imaging System North Pole, will use an array of thick apertures to image the neutrons produced in the burn region of imploding fusion capsules at the National Ignition Facility. While the resolution requirements and parameters that drive the design of this array are similar to traditional x-ray pinhole arrays, neutrons require thick apertures with narrow fields of view, and a precisely designed array of apertures is critical to allow alignment and capture the required images with 10-μm resolution. This work describes the mechanical parameters and limitations driving the design of the aperture array, in addition metrology and alignment requirements are discussed.
- Published
- 2016
30. Aperture design for the third neutron and first gamma-ray imaging systems for the National Ignition Facility
- Author
-
David N. Fittinghoff, Petr Volegov, Carl Wilde, R. L. Hibbard, H. J. Jorgenson, J. I. Martinez, V. E. Fatherley, C. S. Waltz, Derek Schmidt, and John A. Oertel
- Subjects
010302 applied physics ,Physics ,Aperture ,business.industry ,Gamma ray ,01 natural sciences ,010305 fluids & plasmas ,Sight ,Optics ,0103 physical sciences ,Physics::Accelerator Physics ,Neutron ,Plasma diagnostics ,Vacuum chamber ,National Ignition Facility ,business ,Instrumentation ,Inertial confinement fusion - Abstract
The current construction of a new nuclear-imaging view at the National Ignition Facility will provide a third line of sight for hotspot and cold fuel imaging and the first dedicated line of sight for 4.4-MeV γ-ray imaging of the remaining carbon ablator. To minimize the effort required to hold and align apertures inside the vacuum chamber, the apertures for the two lines of sight will be contained in the same array. In this work, we discuss the system requirements for neutron and γ-ray imaging and the resulting aperture array design.
- Published
- 2018
31. One dimensional imager of neutrons on the Z machine
- Author
-
Johan Frenje, D. J. Ampleford, John Fisher, Brent Manley Jones, Jeremy Vaughan, R. D. Petrasso, Patrick Knapp, Carlos L. Ruiz, A. J. Harvey-Thompson, Kelly Hahn, C. R. Ball, Andrew Maurer, Mark May, Maria Gatu-Johnson, Perry Alberto, Gregory Rochau, Gary Wayne Cooper, David N. Fittinghoff, Brandon Lahmann, and Jose A. Torres
- Subjects
Physics ,business.industry ,Track (disk drive) ,Detector ,Resolution (electron density) ,chemistry.chemical_element ,Magnetized Liner Inertial Fusion ,Tungsten ,01 natural sciences ,010305 fluids & plasmas ,Optics ,chemistry ,0103 physical sciences ,Acceptance angle ,Neutron ,Sensitivity (control systems) ,010306 general physics ,business ,Instrumentation - Abstract
We recently developed a one-dimensional imager of neutrons on the Z facility. The instrument is designed for Magnetized Liner Inertial Fusion (MagLIF) experiments, which produce D-D neutrons yields of ∼3 × 1012. X-ray imaging indicates that the MagLIF stagnation region is a 10-mm long, ∼100-μm diameter column. The small radial extents and present yields precluded useful radial resolution, so a one-dimensional imager was developed. The imaging component is a 100-mm thick tungsten slit; a rolled-edge slit limits variations in the acceptance angle along the source. CR39 was chosen as a detector due to its negligible sensitivity to the bright x-ray environment in Z. A layer of high density poly-ethylene is used to enhance the sensitivity of CR39. We present data from fielding the instrument on Z, demonstrating reliable imaging and track densities consistent with diagnosed yields. For yields ∼3 × 1012, we obtain resolutions of ∼500 μm.
- Published
- 2018
32. First D+D neutron image at the National Ignition Facility
- Author
-
L. F. Berzak Hopkins, M. J. Ayers, E. L. Dewald, C. B. Yeamans, Daniel Sayre, S. Le Pape, Doug Wilson, David N. Fittinghoff, Carl Wilde, Daniel Casey, D. H. Munro, Gary Grim, Michael Kruse, V. E. Fatherley, N. Izumi, Robert Hatarik, Frank E. Merrill, Petr Volegov, Raspberry Simpson, Christopher Danly, V. Geppert-Kleinrath, and Steven H. Batha
- Subjects
Physics ,Brightness ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Condensed Matter Physics ,Laser ,01 natural sciences ,010305 fluids & plasmas ,Computational physics ,law.invention ,Deuterium ,Physics::Plasma Physics ,law ,Computer Science::Computer Vision and Pattern Recognition ,0103 physical sciences ,Neutron source ,Neutron ,Nuclear Experiment ,010306 general physics ,National Ignition Facility ,Image resolution - Abstract
First time-integrated neutron images of a deuterium gas filled capsule were obtained using arrival time gating with the Neutron Imaging System at the National Ignition Facility. Images exist from DT (deuterium and tritium mixture) filled capsules in several energy bands but only at the Omega laser had DD (pure deuterium) filled capsules been imaged. A composite image was derived from an assembly of multiple penumbral neutron images using an iterative Maximum Likelihood reconstruction technique. This was compared with a simulated image from a radiation-hydrodynamic calculation. The observed image size, and shape agree, as do the primary DD, secondary DT neutron yields, and the burn duration. However, the observed cross-sectional profiles, although smaller in half width, extend outside the calculated, suggesting that deuterium has mixed outward into the carbon ablator. The observed X-ray image size (61 μm) is larger than the observed neutron image (51 μm). The calculations also reflect this. X-ray brightness includes carbon as well as deuterium emission. A bright spot, “meteor,” in the X-ray image is seen to move in time-gated images, but is not evident in the neutron image. It does not appear to degrade the neutron yield.First time-integrated neutron images of a deuterium gas filled capsule were obtained using arrival time gating with the Neutron Imaging System at the National Ignition Facility. Images exist from DT (deuterium and tritium mixture) filled capsules in several energy bands but only at the Omega laser had DD (pure deuterium) filled capsules been imaged. A composite image was derived from an assembly of multiple penumbral neutron images using an iterative Maximum Likelihood reconstruction technique. This was compared with a simulated image from a radiation-hydrodynamic calculation. The observed image size, and shape agree, as do the primary DD, secondary DT neutron yields, and the burn duration. However, the observed cross-sectional profiles, although smaller in half width, extend outside the calculated, suggesting that deuterium has mixed outward into the carbon ablator. The observed X-ray image size (61 μm) is larger than the observed neutron image (51 μm). The calculations also reflect this. X-ray brightnes...
- Published
- 2018
33. Variable convergence liquid layer implosions on the National Ignition Facility
- Author
-
C. Kong, J. Crippen, Paul A. Bradley, H. Huang, Frank E. Merrill, R. C. Shah, Nathan Meezan, Brian Haines, T. Braun, Steven H. Batha, Michael Stadermann, George A. Kyrala, Suhas Bhandarkar, L. F. Berzak Hopkins, S. Khan, A. Nikroo, C. F. Walters, S. A. Yi, Alex Zylstra, B. J. Kozioziemski, Robert R. Peterson, J. D. Sater, Tammy Ma, Neal Rice, R. J. Leeper, Michael Farrell, Doug Wilson, Petr Volegov, John Kline, J. Biener, David N. Fittinghoff, Hans W. Herrmann, and R. E. Olson
- Subjects
Physics ,Convergence ratio ,Energy loss ,Series (mathematics) ,Liquid layer ,Mechanics ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Liquid fuel ,Condensed Matter::Soft Condensed Matter ,0103 physical sciences ,Convergence (routing) ,010306 general physics ,National Ignition Facility - Abstract
Liquid layer implosions using the “wetted foam” technique, where the liquid fuel is wicked into a supporting foam, have been recently conducted on the National Ignition Facility for the first time [Olson et al., Phys. Rev. Lett. 117, 245001 (2016)]. We report on a series of wetted foam implosions where the convergence ratio was varied between 12 and 20. Reduced nuclear performance is observed as convergence ratio increases. 2-D radiation-hydrodynamics simulations accurately capture the performance at convergence ratios (CR) ∼ 12, but we observe a significant discrepancy at CR ∼ 20. This may be due to suppressed hot-spot formation or an anomalous energy loss mechanism.
- Published
- 2018
34. Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research
- Author
-
Ch Yeamans, Johan Frenje, Daniel Sayre, Gary Grim, L. A. Bernstein, William S. Cassata, L. F. Berzak Hopkins, C. A. Velsko, Michael Wiescher, Kenton J. Moody, Yu. A. Litvinov, C Cerjan, Daniel H. Kalantar, Carl R. Brune, H. G. Rinderknecht, D. A. Shaughnessy, Yong Ho Kim, D. H. Schneider, E. P. Hartouni, David N. Fittinghoff, A. L. Kritcher, N. Izumi, Hans W. Herrmann, Paul Neumayer, R. Tommasini, Maria Gatu-Johnson, R. M. Bionta, D. L. Bleuel, A. Ratkiewicz, Chr Hagmann, N. Gharibyan, E. A. Henry, Wolfgang Stoeffl, Brian Spears, Manoel Couder, Robert Hatarik, Frank E. Merrill, A. V. Hamza, J. A. Caggiano, Alex Zylstra, and Hesham Khater
- Subjects
Physics ,Nuclear and High Energy Physics ,Thermonuclear fusion ,Fission ,Nuclear engineering ,Plasma ,Fusion power ,01 natural sciences ,010305 fluids & plasmas ,Neutron capture ,Physics::Plasma Physics ,0103 physical sciences ,Neutron source ,010306 general physics ,National Ignition Facility ,Inertial confinement fusion - Abstract
The generation of dynamic high energy density plasmas (HEDP) in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of Inertial Confinement Fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capture cross-section evaluation, fission fragment production, and ion energy loss measurement in electron-degenerate plasmas. More generally, the NIF conditions provide a singular environment to investigate the interplay of atomic and nuclear processes such as plasma screening effects upon thermonuclear reactivity. Achieving enhanced understanding of many of these effects will also significantly advance fusion energy research and challenge existing theoretical models.
- Published
- 2018
35. Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using spherical harmonic decomposition
- Author
-
Christopher Danly, Gary Grim, V. Geppert-Kleinrath, David N. Fittinghoff, Frank E. Merrill, Petr Volegov, and Carl Wilde
- Subjects
010302 applied physics ,Physics ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Gamma ray ,General Physics and Astronomy ,Spherical harmonics ,01 natural sciences ,010305 fluids & plasmas ,Optics ,Physics::Plasma Physics ,0103 physical sciences ,Neutron source ,Neutron ,Plasma diagnostics ,business ,National Ignition Facility ,Inertial confinement fusion - Abstract
Neutron, gamma-ray, and x-ray imaging are important diagnostic tools at the National Ignition Facility (NIF) for measuring the two-dimensional (2D) size and shape of the neutron producing region, for probing the remaining ablator and measuring the extent of the DT plasmas during the stagnation phase of Inertial Confinement Fusion implosions. Due to the difficulty and expense of building these imagers, at most only a few two-dimensional projections images will be available to reconstruct the three-dimensional (3D) sources. In this paper, we present a technique that has been developed for the 3D reconstruction of neutron, gamma-ray, and x-ray sources from a minimal number of 2D projections using spherical harmonics decomposition. We present the detailed algorithms used for this characterization and the results of reconstructed sources from experimental neutron and x-ray data collected at OMEGA and NIF.
- Published
- 2017
36. Multi-axis neutron imaging at the National Ignition Facility
- Author
-
Raspberry Simpson, Carl Wilde, K. Christensen, Gary Grim, Frank E. Merrill, Petr Volegov, R. Bettencourt, N. Shingleton, David N. Fittinghoff, D. R. Jedlovec, V. E. Fatherley, and R. L. Hibbard
- Subjects
Physics ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Equator ,Implosion ,Field of view ,Plasma ,Nuclear physics ,Optics ,Physics::Plasma Physics ,Neutron ,Nuclear Experiment ,business ,National Ignition Facility ,Inertial confinement fusion - Abstract
Inertial confinement fusion experiments at the National Ignition Facility (NIF) rely on a neutron imager to measure the 2D size and shape of the neutron-producing region in the burning deuterium-tritium plasma. Since the existing neutron imager is located on the equator of the NIF chamber, it provides only one view of the plasma, which complicates understanding the inherently three-dimensional nature of the implosion. Attempts to use x-ray images combined with the neutron image to improve our understanding of the 3D neutron-burn volume have proved to be inconsistent with the fuel mass. This result is understandable since neutrons and x-rays are not produced or propagated in the same manner. Thus, it is desirable to use multiple neutron imagers, and we are designing two neutron imagers on lines of sight that are nearly orthogonal to the current imager, one near the pole of the chamber and one near the equator, for fielding on the NIF in the next five years. In this paper, we will discuss the current designs, including the resolution, field of view and placement in the facility that will be required to use the three orthogonal neutron imagers to measure the neutron burn volume of plasmas at NIF. Prepared by LLNL under Contract DE-AC52-07NA27344.
- Published
- 2015
37. Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility
- Author
-
Denise Hinkel, S. Le Pape, H. Streckert, Hans W. Herrmann, David N. Fittinghoff, D. K. Bradley, Robert Hatarik, Klaus Widmann, P. T. Springer, George A. Kyrala, Harry Robey, D. A. Callahan, Daniel Sayre, C. B. Yeamans, M. Havre, E. L. Dewald, Alan S. Wan, T. Ma, S. W. Haan, Joseph Ralph, Otto Landen, Peter M. Celliers, R. Tommasini, Gary Grim, Petr Volegov, P. K. Patel, Michael Schneider, Nobuhiko Izumi, Jay D. Salmonson, Alastair Moore, J. A. Caggiano, Bruce Remington, E. J. Bond, Abbas Nikroo, Johan Frenje, H.-S. Park, Omar Hurricane, Andrea Kritcher, Carl Wilde, Frank E. Merrill, Daniel Casey, M. J. Edwards, Tilo Döppner, Art Pak, J. P. Knauer, T. R. Dittrich, L. F. Berzak Hopkins, D. H. Edgell, John Kline, Andrew MacPhee, J. A. Church, David Turnbull, M. Gatu Johnson, John Moody, S. N. Dixit, Laura Robin Benedetti, Richard Town, and Shahab Khan
- Subjects
Materials science ,Nuclear engineering ,General Physics and Astronomy ,Implosion ,chemistry.chemical_element ,Nova (laser) ,Fusion power ,Uranium ,law.invention ,Nuclear physics ,Ignition system ,chemistry ,Hohlraum ,law ,Depleted uranium ,National Ignition Facility - Abstract
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.
- Published
- 2015
38. Simultaneous neutron and x-ray imaging of inertial confinement fusion experiments along a single line of sight at Omega
- Author
-
Yong Ho Kim, Hans W. Herrmann, Christopher Danly, Thomas Day, Petr Volegov, J. I. Martinez, Frank E. Merrill, David N. Fittinghoff, Raspberry Simpson, Derek Schmidt, N. Izumi, and Carl Wilde
- Subjects
Physics ,Line-of-sight ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Iterative reconstruction ,Optics ,Physics::Plasma Physics ,Neutron source ,Plasma diagnostics ,Neutron ,business ,National Ignition Facility ,Instrumentation ,Inertial confinement fusion - Abstract
Neutron and x-ray imaging provide critical information about the geometry and hydrodynamics of inertial confinement fusion implosions. However, existing diagnostics at Omega and the National Ignition Facility (NIF) cannot produce images in both neutrons and x-rays along the same line of sight. This leads to difficulty comparing these images, which capture different parts of the plasma geometry, for the asymmetric implosions seen in present experiments. Further, even when opposing port neutron and x-ray images are available, they use different detectors and cannot provide positive information about the relative positions of the neutron and x-ray sources. A technique has been demonstrated on implosions at Omega that can capture x-ray images along the same line of sight as the neutron images. The technique is described, and data from a set of experiments are presented, along with a discussion of techniques for coregistration of the various images. It is concluded that the technique is viable and could provide valuable information if implemented on NIF in the near future.
- Published
- 2015
39. First High-Convergence Cryogenic Implosion in a Near-Vacuum Hohlraum
- Author
-
J. D. Moody, Michael Stadermann, Andrew MacPhee, George A. Kyrala, E. Woerner, J. A. Church, D. A. Callahan, Gary Grim, Daniel Sayre, Abbas Nikroo, T. Ma, Wolfgang Stoeffl, Laurent Divol, James Ross, L. F. Berzak Hopkins, D. Hoover, Mark Eckart, Laura Robin Benedetti, Robert Hatarik, M. Gatu Johnson, Richard Town, A. J. Mackinnon, Shahab Khan, Hans W. Herrmann, Frank E. Merrill, S. M. Sepke, J. A. Caggiano, Jeremy Kroll, Harry Robey, James McNaney, Rebecca Dylla-Spears, C. B. Yeamans, A. V. Hamza, H. Huang, E. P. Hartouni, Matthias Hohenberger, David C. Clark, J. D. Kilkenny, Carl Wilde, D. H. Edgell, Darwin Ho, P. K. Patel, M. J. Edwards, Tilo Döppner, Art Pak, Nobuhiko Izumi, Denise Hinkel, Cliff Thomas, Jose Milovich, R. M. Bionta, Joseph Ralph, Otto Landen, B. E. Yoxall, Michael Schneider, Nathan Meezan, J. Sater, S. Le Pape, Petr Volegov, N. Guler, C. J. Cerjan, David N. Fittinghoff, C. Wild, D. K. Bradley, B. J. Kozioziemski, J. E. Field, O. S. Jones, E. J. Bond, Juergen Biener, S. W. Haan, W. W. Hsing, and J. R. Rygg
- Subjects
Physics ,business.industry ,General Physics and Astronomy ,Implosion ,Plasma ,Laser ,Symmetry (physics) ,Pulse (physics) ,law.invention ,Nuclear physics ,Optics ,Physics::Plasma Physics ,Hohlraum ,law ,Neutron ,National Ignition Facility ,business - Abstract
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.
- Published
- 2015
40. Thin Shell, High Velocity Inertial Confinement Fusion Implosions on the National Ignition Facility
- Author
-
T. G. Parham, J. Sater, S. Le Pape, George A. Kyrala, D. A. Callahan, Jay D. Salmonson, T. Ma, David N. Fittinghoff, Nobuhiko Izumi, D. K. Bradley, Joseph Ralph, R. M. Bionta, Otto Landen, O. S. Jones, Peter M. Celliers, Hans W. Herrmann, M. D. Rosen, E. L. Dewald, Robert Hatarik, S. N. Dixit, B. J. MacGowan, E. J. Bond, Gary Grim, Abbas Nikroo, M. A. Barrios, Rebecca Dylla-Spears, J. P. Knauer, Andrew MacPhee, B. J. Kozioziemski, Daniel Sayre, J. E. Field, J. A. Church, D. Shaughnessy, D. H. Edgell, Denise Hinkel, Nathan Meezan, Laura Robin Benedetti, P. K. Patel, Richard Town, P. T. Springer, T. Kohut, Shahab Khan, W. W. Hsing, Daniel Casey, J. D. Kilkenny, Harry Robey, Alan S. Wan, J. D. Moody, C. B. Yeamans, C. J. Cerjan, J. A. Caggiano, M. Gatu Johnson, Carl Wilde, Bruce Remington, Andrea Kritcher, A. J. Mackinnon, M. J. Edwards, Tilo Döppner, Art Pak, Frank E. Merrill, J. R. Rygg, Marilyn Schneider, Klaus Widmann, T. R. Dittrich, Petr Volegov, L. F. Berzak Hopkins, S. W. Haan, R. Tommasini, Johan Frenje, H.-S. Park, Omar Hurricane, S. R. Nagel, Brian Spears, and N. Guler
- Subjects
Physics ,business.industry ,General Physics and Astronomy ,Feedthrough ,Hot spot (veterinary medicine) ,Laser ,Instability ,law.invention ,Ignition system ,Nominal size ,Optics ,law ,National Ignition Facility ,business ,Inertial confinement fusion - Abstract
Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 μm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1/2 the neutron yield coming from α-particle self-heating.
- Published
- 2015
41. Self characterization of a coded aperture array for neutron source imaging
- Author
-
Frank E. Merrill, N. Guler, David N. Fittinghoff, Petr Volegov, Christopher Danly, and Carl Wilde
- Subjects
Physics ,business.industry ,Aperture ,Neutron imaging ,Implosion ,Optics ,Physics::Plasma Physics ,Physics::Accelerator Physics ,Neutron source ,Pinhole (optics) ,Coded aperture ,business ,National Ignition Facility ,Instrumentation ,Inertial confinement fusion - Abstract
The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.
- Published
- 2015
42. Getting Beyond Unity Fusion Fuel Gain in an Inertially Confined Fusion Implosion
- Author
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J. D. Moody, S. N. Dixit, D. Edgell, John Kline, Laurent Divol, N. Meezan, S. Ross, Darwin Ho, Daniel Casey, Gary Grim, E. L. Dewald, J. P. Knauer, A. L. Kritcher, J. A. Caggiano, Bruce Remington, O. S. Jones, S. W. Haan, P. T. Springer, Tammy Ma, Andrew MacPhee, J.-P. Leidinger, Arthur Pak, Joseph Ralph, Brian Spears, E. J. Bond, Otto Landen, A. J. Mackinnon, George A. Kyrala, Harry Robey, Daniel S. Clark, Debra Callahan, T. R. Dittrich, Laura Robin Benedetti, Michael Schneider, Abbas Nikroo, H-S Park, Frank E. Merrill, Richard Town, Sabrina Nagel, M. A. Barrios Garcia, W. W. Hsing, Carl Wilde, A. S. Moore, Maria Gatu-Johnson, M. J. Edwards, Larry L. Peterson, Petr Volegov, L. F. Berzak Hopkins, S. Le Pape, D. Hoover, Denise Hinkel, Cliff Thomas, R. Rygg, Shabbir A. Khan, David N. Fittinghoff, Peter Amendt, D. K. Bradley, Matthias Hohenberger, Jay D. Salmonson, A. V. Hamza, Tilo Doeppner, R. Tommasini, Johan Frenje, Omar Hurricane, Pierre Michel, V. A. Smalyuk, P. K. Patel, Jose Milovich, Klaus Widmann, R. Haterik, and N. Izumi
- Subjects
Ignition system ,Fusion ,law ,Nuclear engineering ,Environmental science ,Implosion ,Nova (laser) ,Plasma ,Fusion power ,National Ignition Facility ,Inertial confinement fusion ,law.invention - Abstract
In this talk, we will discuss the progress towards ignition on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Northern California. We will cover the some of the setbacks encountered during the progress of the research at NIF, but also cover the great advances that have been made including the achievements of greater than unity fusion ‘fuel gain’ and alpha-heating dominated fusion plasmas. The research strategy for the future will also be discussed.
- Published
- 2015
43. A concept to collect neutron and x-ray images on the same line of sight at NIF
- Author
-
Frank E. Merrill, Gary Grim, Christopher Danly, David N. Fittinghoff, Petr Volegov, D. R. Jedlovec, H.-S. Park, Arthur Pak, Carl Wilde, and N. Izumi
- Subjects
Physics ,Line-of-sight ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Neutron imaging ,Equator ,Nuclear physics ,Optics ,Physics::Plasma Physics ,Computer Science::Computer Vision and Pattern Recognition ,Neutron detection ,Neutron ,Pinhole (optics) ,National Ignition Facility ,business ,Instrumentation ,Inertial confinement fusion - Abstract
Neutron and x-ray images are collected at the National Ignition Facility (NIF) to measure the size and shape of inertial confinement fusion implosions. The x-ray images provide a measure of the size and shape of the hot region of the deuterium-tritium fuel while the neutron images provide a measure of the size and shape of the burning plasma. Although these two types of images are collected simultaneously, they are not collected along the same line of sight (LOS). One 14 MeV neutron image is collected on the NIF equator, and two x-ray images are collected along the polar axis and nearly perpendicular to the neutron imaging line of sight on the equator. Both measurements use pinhole apertures to form the images, but existing x-ray imaging provides time-resolved measurements while the neutron images are time-integrated. Detailed comparisons of the x-ray and neutron images can provide information on the fuel assembly, but these studies have been limited because the implosions are not azimuthally symmetric and the images are collected along different LOS. We have developed a conceptual design of a time-integrated x-ray imaging system that could be added to the existing neutron imaging LOS. This new system would allow these detailed studies, providing important information on the fuel assembly of future implosions. Here we present this conceptual design and the expected performance characteristics.
- Published
- 2014
44. Spatial and temporal characterizations of femtosecond pulses at high-numerical aperture using collinear, background-free, third-harmonic autocorrelation
- Author
-
Jeff Squier, David N. Fittinghoff, and Jürg Aus der Au
- Subjects
Physics ,Microscope ,business.industry ,Autocorrelation ,Plane wave ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Numerical aperture ,Optics ,law ,Femtosecond ,Physics::Accelerator Physics ,High harmonic generation ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,business ,Beam (structure) - Abstract
We show that a simple plane wave analysis can be used even under tight focusing conditions to predict the dependence of third-harmonic generation on the polarization state of the incident beam. Exploiting this fact, we then show that circularly polarized beams may be used to spatially characterize the beam focus and temporally characterize ultrashort pulses in high numerical aperture systems by experimentally demonstrating, for the first time, novel collinear, background-free, third-harmonic intensity autocorrelations in time and space in a high numerical aperture microscope. We also discuss the possibility of using third-harmonic generation with circularly polarized beams for background-free collinear frequency-resolved optical gating.
- Published
- 2005
45. An overview of LLNL high-energy short-pulse technology for advanced radiography of laser fusion experiments
- Author
-
Mary L. Spaeth, J.A. Britten, Edward I. Moses, Scott C. Mitchell, William A. Molander, Deanna Marie Pennington, Kenneth M. Skulina, S J Bryan, G. Beer, John K. Crane, T C Carlson, Jay W. Dawson, Benoit Wattellier, John A. Caird, David N. Fittinghoff, Brent C. Stuart, Michael C. Rushford, Curly R. Hoaglan, Alvin C. Erlandson, Mark R. Hermann, G. L. Tietbohl, L. Jones, M. H. Key, Christopher P. J. Barty, Otto Landen, Igor Jovanovic, A. Iyer, Curtis G. Brown, A.M. Komashko, H. Nguyen, L. Risinger, S.A. Payne, J D Nissen, Raymond J. Beach, Norman D. Nielsen, and Z. Liao
- Subjects
Physics ,Chirped pulse amplification ,Nuclear and High Energy Physics ,Physics::Instrumentation and Detectors ,business.industry ,Condensed Matter Physics ,IGNITOR ,Laser ,law.invention ,Optics ,Physics::Plasma Physics ,law ,Industrial radiography ,Picosecond ,Physics::Accelerator Physics ,business ,National Ignition Facility ,Inertial confinement fusion ,Ultrashort pulse - Abstract
The technical challenges and motivations for high-energy, short-pulse generation with the National Ignition Facility (NIF) and possibly other large-scale Nd : glass lasers are reviewed. High-energy short-pulse generation (multi-kilojoule, picosecond pulses) will be possible via the adaptation of chirped pulse amplification laser techniques on NIF. Development of metre-scale, high-efficiency, high-damage-threshold final optics is a key technical challenge. In addition, deployment of high energy petawatt (HEPW) pulses on NIF is constrained by existing laser infrastructure and requires new, compact compressor designs and short-pulse, fibre-based, seed-laser systems. The key motivations for HEPW pulses on NIF is briefly outlined and includes high-energy, x-ray radiography, proton beam radiography, proton isochoric heating and tests of the fast ignitor concept for inertial confinement fusion.
- Published
- 2004
46. Characterization of a bright, tunable, ultrafast Compton scattering X-ray source
- Author
-
Aaron Tremaine, W. J. Brown, S.G. Anderson, James Rosenzweig, David N. Fittinghoff, G. P. Le Sage, Christopher P. J. Barty, R.R. Cross, Alan J Wootton, E. P. Hartouni, D. R. Slaughter, Frederic V. Hartemann, P. T. Springer, John K. Crane, Arthur K. Kerman, Jaroslav Kuba, David Gibson, Shawn Betts, and Rex Booth
- Subjects
Physics ,Photon ,business.industry ,Compton scattering ,Pulse duration ,Photon energy ,Condensed Matter Physics ,Laser ,Atomic and Molecular Physics, and Optics ,law.invention ,Full width at half maximum ,Optics ,law ,Relativistic electron beam ,Electrical and Electronic Engineering ,Atomic physics ,business ,Ultrashort pulse - Abstract
The Compton scattering of a terawatt-class, femtosecond laser pulse by a high-brightness, relativistic electron beam has been demonstrated as a viable approach toward compact, tunable sources of bright, femtosecond, hard X-ray flashes. The main focus of this article is a detailed description of such a novel X-ray source, namely the PLEIADES (Picosecond Laser–Electron Inter-Action for the Dynamical Evaluation of Structures) facility at Lawrence Livermore National Laboratory. PLEIADES has produced first light at 70 keV, thus enabling critical applications, such as advanced backlighting for the National Ignition Facility andin situtime-resolved studies of high-Zmaterials. To date, the electron beam has been focused down to σx= σy= 27 μm rms, at 57 MeV, with 266 pC of charge, a relative energy spread of 0.2%, a normalized horizontal emittance of 3.5 mm·mrad, a normalized vertical emittance of 11 mm·mrad, and a duration of 3 ps rms. The compressed laser pulse energy at focus is 480 mJ, the pulse duration 54 fs Intensity Full Width at Half-Maximum (IFWHM), and the 1/e2radius 36 μm. Initial X rays produced by head-on collisions between the laser and electron beams at a repetition rate of 10 Hz were captured with a cooled CCD using a CsI scintillator; the peak photon energy was approximately 78 keV, and the observed angular distribution was found to agree very well with three-dimensional codes. The current X-ray dose is 3 × 106photons per pulse, and the inferred peak brightness exceeds 1015photons/(mm2× mrad2× s × 0.1% bandwidth). Spectral measurements using calibrated foils of variable thickness are consistent with theory. Measurements of the X-ray dose as a function of the delay between the laser and electron beams show a 24-ps full width at half maximum (FWHM) window, as predicted by theory, in contrast with a measured timing jitter of 1.2 ps, which contributes to the stability of the source. In addition,K-edge radiographs of a Ta foil obtained at different electron beam energies clearly demonstrate the γ2-tunability of the source and show very good agreement with the theoretical divergence-angle dependence of the X-ray spectrum. Finally, electron bunch shortening experiments using velocity compression have also been performed and durations as short as 300 fs rms have been observed using coherent transition radiation; the corresponding inferred peak X-ray flux approaches 1019photons/s.
- Published
- 2004
47. PLEIADES: A picosecond Compton scattering x-ray source for advanced backlighting and time-resolved material studies
- Author
-
Alan J Wootton, Jaroslav Kuba, David Gibson, John K. Crane, W. J. Brown, Christopher P. J. Barty, E. P. Hartouni, Gregory P. Le Sage, Aaron Tremaine, D. R. Slaughter, James Rosenzweig, David N. Fittinghoff, Rex Booth, Fred Hartemann, S. Anderson, P. T. Springer, Robert R. Cross, and Shawn Betts
- Subjects
Physics ,Scintillation ,Photon ,business.industry ,Compton scattering ,Photon energy ,Scintillator ,Condensed Matter Physics ,Laser ,law.invention ,Optics ,law ,Picosecond ,Physics::Accelerator Physics ,Thermal emittance ,Atomic physics ,business - Abstract
The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 μm rms, at 57 MeV, with 260 pC of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820 nm laser pulse had an energy of 180 mJ and a duration of 54 fs. Initial x rays were captured with a cooled charge-coupled device using a cesium iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3×106 photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-...
- Published
- 2004
48. Short-pulse, high-brightness X-ray production with the PLEIADES Thomson-scattering source
- Author
-
Jaroslav Kuba, David Gibson, James Rosenzweig, W. J. Brown, David N. Fittinghoff, G. P. LeSage, S.G. Anderson, Aaron Tremaine, P. T. Springer, Shawn Betts, D. R. Slaughter, Frederic V. Hartemann, Christopher P. J. Barty, R.R. Cross, and John K. Crane
- Subjects
Physics ,Brightness ,Photon ,Physics and Astronomy (miscellaneous) ,Thomson scattering ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,General Engineering ,General Physics and Astronomy ,Particle accelerator ,Laser ,law.invention ,Optics ,law ,Picosecond ,Cathode ray ,Physics::Accelerator Physics ,Atomic physics ,business ,Ultrashort pulse - Abstract
PLEIADES is a compact, tunable, high-brightness, ultra-short-pulse, Thomson-scattering X-ray source. Picosecond pulses of hard X-rays (10–200 keV) are created by colliding an ultra-relativistic (20–100 MeV), picosecond-duration electron beam with a high-intensity, sub-picosecond, 800-nm laser pulse. Initial operation of this source has produced 78-keV X-rays with 106 photons per pulse using a 57-MeV, 0.3-nC, 50-μm rms width electron beam and a 180-mJ, 15-μm rms width laser pulse. The angular distribution, energy, and energy spectrum of the source are found to agree well with theory and simulations. Source optimization is expected to increase X-ray output to between 107 and 108 photons per pulse with a peak brightness approaching 1020 photons/s/0.1% bandwidth/mm2/mrad2.
- Published
- 2004
49. Mix and hydrodynamic instabilities on NIF
- Author
-
O. S. Jones, Peter M. Celliers, D. Martinez, E. J. Bond, Robert Hatarik, M. Gatu Johnson, J. Crippen, J. L. Peterson, Jeremy Kroll, Kenneth S. Jancaitis, N. Gharibyan, S. Khan, Daniel Sayre, Laurent Masse, Brian Spears, B. J. MacGowan, L. F. Berzak Hopkins, J. E. Field, K. N. LaFortune, A. V. Hamza, Michael Farrell, Tammy Ma, B. A. Hammel, J. A. Caggiano, Bruce Remington, Daniel S. Clark, Debra Callahan, B. Bachmann, Sabrina Nagel, V. A. Smalyuk, Omar Hurricane, Jose Milovich, P. K. Patel, J. Pino, S. W. Haan, Kumar Raman, S. Felker, C. R. Weber, C. J. Cerjan, Daniel Casey, R. Tommasini, Alastair Moore, Otto Landen, W. W. Hsing, David N. Fittinghoff, Kevin Baker, Harry Robey, Arthur Pak, C. C. Widmayer, Michael Stadermann, A. Nikroo, C. B. Yeamans, Matthias Hohenberger, Petr Volegov, Robert Tipton, Andrew MacPhee, S. N. Dixit, Louisa Pickworth, Neal Rice, E. M. Giraldez, Carl Wilde, M. J. Edwards, Tilo Döppner, and Gary Grim
- Subjects
Materials science ,Fluid mechanics ,Hot spot (veterinary medicine) ,Mechanics ,01 natural sciences ,Instability ,010305 fluids & plasmas ,law.invention ,Ignition system ,Acceleration ,Physics::Plasma Physics ,law ,Industrial radiography ,0103 physical sciences ,010306 general physics ,National Ignition Facility ,Instrumentation ,Inertial confinement fusion ,Mathematical Physics - Abstract
Several new platforms have been developed to experimentally measure hydrodynamic instabilities in all phases of indirect-drive, inertial confinement fusion implosions on National Ignition Facility. At the ablation front, instability growth of pre-imposed modulations was measured with a face-on, x-ray radiography platform in the linear regime using the Hydrodynamic Growth Radiography (HGR) platform. Modulation growth of "native roughness" modulations and engineering features (fill tubes and capsule support membranes) were measured in conditions relevant to layered DT implosions. A new experimental platform was developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, several experimental platforms were developed to measure both low-mode asymmetries and high-mode perturbations near peak compression with x-ray and nuclear techniques. In one innovative technique, the self-emission from the hot spot was enhanced with argon dopant to "self-backlight" the shell in-flight. To stabilize instability growth, new "adiabat-shaping" techniques were developed using the HGR platform and applied in layered DT implosions.
- Published
- 2017
50. Symmetry control of an indirectly driven high-density-carbon implosion at high convergence and high velocity
- Author
-
Nobuhiko Izumi, Andrew MacPhee, H. Huang, L. F. Berzak Hopkins, James Ross, Clement Goyon, J. E. Field, Daniel Sayre, David Turnbull, C. Kong, C. R. Weber, Daniel Casey, William S. Cassata, Peter M. Celliers, Omar Hurricane, Pierre Michel, David Strozzi, W. W. Hsing, A. J. Mackinnon, Otto Landen, Michael Stadermann, J. Crippen, Darwin Ho, S. Le Pape, J. R. Rygg, Laurent Divol, M. J. Edwards, Tilo Döppner, Art Pak, Juergen Biener, S. W. Haan, B. J. MacGowan, B. J. Kozioziemski, David N. Fittinghoff, S. R. Nagel, C. B. Yeamans, Matthias Hohenberger, Benjamin Bachmann, Nathan Meezan, Marius Millot, Neal Rice, A. Nikroo, J. D. Moody, Laura Robin Benedetti, Richard Town, Shahab Khan, C. Choate, Petr Volegov, D. H. Edgell, George A. Kyrala, D. A. Callahan, T. Ma, Suhas Bhandarkar, N. Gharibyan, Robert Hatarik, and E. L. Dewald
- Subjects
Physics ,media_common.quotation_subject ,Implosion ,Condensed Matter Physics ,01 natural sciences ,Asymmetry ,Symmetry (physics) ,010305 fluids & plasmas ,Computational physics ,law.invention ,Ignition system ,Acceleration ,law ,Hohlraum ,0103 physical sciences ,Plasma diagnostics ,Atomic physics ,010306 general physics ,National Ignition Facility ,media_common - Abstract
We report on the most recent and successful effort at controlling the trajectory and symmetry of a high density carbon implosion at the National Ignition Facility. We use a low gasfill (0.3 mg/cc He) bare depleted uranium hohlraum with around 1 MJ of laser energy to drive a 3-shock-ignition relevant implosion. We assess drive performance and we demonstrate symmetry control at convergence 1, 3–5, 12, and 27 to better than ±5 μm using a succession of experimental platforms. The symmetry control was maintained at a peak fuel velocity of 380 km/s. Overall, implosion symmetry measurements are consistent with the pole-equator symmetry of the X-ray drive on the capsule being better than 5% in the foot of the drive (when shocks are launched) and better than 1% during peak drive (main acceleration phase). This level of residual asymmetry should have little impact on implosion performance.
- Published
- 2017
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