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L. J. Atherton

Bio: L. J. Atherton is an academic researcher from Lawrence Livermore National Laboratory. The author has contributed to research in topics: National Ignition Facility & Ignition system. The author has an hindex of 31, co-authored 57 publications receiving 3298 citations.


Papers
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Journal ArticleDOI
TL;DR: Miller et al. as discussed by the authors proposed a point design for the initial ignition campaign on the National Ignition Facility (NIF) using D-T fusion fuel in an ablator of either CH with Ge doping, or Be with Cu.
Abstract: Point design targets have been specified for the initial ignition campaign on the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)]. The targets contain D-T fusion fuel in an ablator of either CH with Ge doping, or Be with Cu. These shells are imploded in a U or Au hohlraum with a peak radiation temperature set between 270 and 300 eV. Considerations determining the point design include laser-plasma interactions, hydrodynamic instabilities, laser operations, and target fabrication. Simulations were used to evaluate choices, and to define requirements and specifications. Simulation techniques and their experimental validation are summarized. Simulations were used to estimate the sensitivity of target performance to uncertainties and variations in experimental conditions. A formalism is described that evaluates margin for ignition, summarized in a parameter the Ignition Threshold Factor (ITF). Uncertainty and shot-to-shot variability in ITF are evaluated, and...

534 citations

Journal ArticleDOI
05 Mar 2010-Science
TL;DR: Experiments at the National Ignition Facility indicate that the conditions are suitable for compressing deuterium-tritium–filled capsules, with the goal of achieving burning fusion plasmas and energy gain in the laboratory.
Abstract: Indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 megajoule. One hundred and ninety-two simultaneously fired laser beams heat ignition-emulate hohlraums to radiation temperatures of 3.3 million kelvin, compressing 1.8-millimeter-diameter capsules by the soft x-rays produced by the hohlraum. Self-generated plasma optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum, which produces a symmetric x-ray drive as inferred from the shape of the capsule self-emission. These experiments indicate that the conditions are suitable for compressing deuterium-tritium–filled capsules, with the goal of achieving burning fusion plasmas and energy gain in the laboratory.

308 citations

Journal ArticleDOI
M. J. Edwards1, P. K. Patel, J. D. Lindl1, L. J. Atherton, Siegfried Glenzer, S. W. Haan, J. D. Kilkenny, O. L. Landen, Edward I. Moses, A. Nikroo, R. D. Petrasso, T. C. Sangster, P. T. Springer, Steven H. Batha, R. Benedetti, L. A. Bernstein, Riccardo Betti, D. L. Bleuel, T. R. Boehly, D. K. Bradley, J. A. Caggiano, D. A. Callahan, P. M. Celliers, C. J. Cerjan, K. C. Chen, Daniel Clark, Gilbert Collins, E. L. Dewald, Laurent Divol, S. N. Dixit, Tilo Doeppner, D. H. Edgell, James E. Fair, Michael Farrell, R. J. Fortner, Johan Frenje, M. Gatu Johnson, E. M. Giraldez, V. Yu. Glebov, Gary Grim, B. A. Hammel, A. V. Hamza, D. R. Harding, S. P. Hatchett, N. Hein, Hans W. Herrmann, Damien Hicks, D. E. Hinkel, M. Hoppe, W. W. Hsing, Nobuhiko Izumi, B. Jacoby, O. S. Jones, Daniel H. Kalantar, Robert L. Kauffman, John Kline, J. P. Knauer, J. A. Koch, B. J. Kozioziemski, G. A. Kyrala, K. N. LaFortune, S. Le Pape, R. J. Leeper, R. A. Lerche, T. Ma, B. J. MacGowan, A. J. Mackinnon, Andrew MacPhee, Evan Mapoles, M. M. Marinak, M. Mauldin, P. W. McKenty, M. Meezan, Pierre Michel, Jose Milovich, J. D. Moody, Matthew Moran, D. H. Munro, C. L. Olson, Kathy Opachich, Art Pak, T. G. Parham, H.-S. Park, Joseph Ralph, Sean Regan, Bruce Remington, H. G. Rinderknecht, Harry Robey, M. D. Rosen, Steven Ross, Jay D. Salmonson, J. D. Sater, D. H. Schneider, Fredrick Seguin, Scott Sepke, D. A. Shaughnessy, V. A. Smalyuk, Brian Spears, Christian Stoeckl, Wolfgang Stoeffl, L. J. Suter, Cliff Thomas, R. Tommasini, Richard Town, S. V. Weber, Paul J. Wegner, K. Widman, Mark D. Wilke, Doug Wilson, Charles Yeamans, Alex Zylstra 
TL;DR: In this paper, a low-Z capsule filled with deuterium-tritium (DT) fuel via laser indirect-drive inertial confinement fusion and demonstrate fusion ignition and propagating thermonuclear burn with a net energy gain of ∼5-10 (fusion yield/input laser energy).
Abstract: The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory includes a precision laser system now capable of delivering 1.8 MJ at 500 TW of 0.35-μm light to a target. NIF has been operational since March 2009. A variety of experiments have been completed in support of NIF's mission areas: national security, fundamental science, and inertial fusion energy. NIF capabilities and infrastructure are in place to support its missions with nearly 60 X-ray, optical, and nuclear diagnostic systems. A primary goal of the National Ignition Campaign (NIC) on the NIF was to implode a low-Z capsule filled with ∼0.2 mg of deuterium-tritium (DT) fuel via laser indirect-drive inertial confinement fusion and demonstrate fusion ignition and propagating thermonuclear burn with a net energy gain of ∼5–10 (fusion yield/input laser energy). This requires assembling the DT fuel into a dense shell of ∼1000 g/cm3 with an areal density (ρR) of ∼1.5 g/cm2, surrounding a lower density hot spot with a temperature of ∼10 keV and a ρR ∼0.3 g/cm2, or approximately an α-particle range. Achieving these conditions demand precise control of laser and target parameters to allow a low adiabat, high convergence implosion with low ablator fuel mix. We have demonstrated implosion and compressed fuel conditions at ∼80–90% for most point design values independently, but not at the same time. The nuclear yield is a factor of ∼3–10× below the simulated values and a similar factor below the alpha dominated regime. This paper will discuss the experimental trends, the possible causes of the degraded performance (the off-set from the simulations), and the plan to understand and resolve the underlying physics issues.

271 citations

Journal ArticleDOI
TL;DR: The comparison with radiation-hydrodynamic modeling indicates that low mode asymmetries and increased ablator surface perturbations may be responsible for the current performance of deuterium-tritium inertial confinement fusion implosion experiments.
Abstract: Deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility have demonstrated yields ranging from 0.8 to $7\ifmmode\times\else\texttimes\fi{}{10}^{14}$, and record fuel areal densities of 0.7 to $1.3\text{ }\text{ }\mathrm{g}/{\mathrm{cm}}^{2}$. These implosions use hohlraums irradiated with shaped laser pulses of 1.5--1.9 MJ energy. The laser peak power and duration at peak power were varied, as were the capsule ablator dopant concentrations and shell thicknesses. We quantify the level of hydrodynamic instability mix of the ablator into the hot spot from the measured elevated absolute x-ray emission of the hot spot. We observe that DT neutron yield and ion temperature decrease abruptly as the hot spot mix mass increases above several hundred ng. The comparison with radiation-hydrodynamic modeling indicates that low mode asymmetries and increased ablator surface perturbations may be responsible for the current performance.

215 citations

Journal ArticleDOI
TL;DR: In this paper , the authors achieved a burning-plasma state in the laboratory using a strategy to increase the spatial scale of the capsule through two different implosion concepts and showed that fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burningplasma metrics.
Abstract: Obtaining a burning plasma is a critical step towards self-sustaining fusion energy1. A burning plasma is one in which the fusion reactions themselves are the primary source of heating in the plasma, which is necessary to sustain and propagate the burn, enabling high energy gain. After decades of fusion research, here we achieve a burning-plasma state in the laboratory. These experiments were conducted at the US National Ignition Facility, a laser facility delivering up to 1.9 megajoules of energy in pulses with peak powers up to 500 terawatts. We use the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule via the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work. The burning-plasma state was created using a strategy to increase the spatial scale of the capsule2,3 through two different implosion concepts4-7. These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics3,8. Additionally, we describe a subset of experiments that appear to have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction. These results provide an opportunity to study α-particle-dominated plasmas and burning-plasma physics in the laboratory.

193 citations


Cited by
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Journal ArticleDOI
20 Feb 2014-Nature
TL;DR: In this article, the authors report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a high-foot implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion.
Abstract: Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium-tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a 'high-foot' implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite.

733 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed accurate x-ray scattering techniques to measure the physical properties of dense plasmas for applications in high energy density physics, including inertial confinement fusion, material science, or laboratory astrophysics.
Abstract: Accurate x-ray scattering techniques to measure the physical properties of dense plasmas have been developed for applications in high energy density physics. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines, allowing spectrally resolved x-ray scattering measurements from these plasmas. The backscattering spectrum accesses the noncollective Compton scattering regime which provides accurate diagnostic information on the temperature, density, and ionization state. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions and quantum effects. Dense matter theory relates scattering spectra with the dielectric function and structure factors that determine the physical properties of matter. Applications to radiation-heated and shock-compressed matter have demonstrated accurate measurements of compression and heating with up to picosecond temporal resolution. The ongoing development of suitable x-ray sources and facilities will enable experiments in a wide range of research areas including inertial confinement fusion,more » radiation hydrodynamics, material science, or laboratory astrophysics.« less

612 citations

Journal ArticleDOI
TL;DR: In this article, Zhou et al. presented the initial condition dependence of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) mixing layers, and introduced parameters that are used to evaluate the level of mixedness and mixed mass within the layers.

606 citations

Journal ArticleDOI
TL;DR: Miller et al. as discussed by the authors proposed a point design for the initial ignition campaign on the National Ignition Facility (NIF) using D-T fusion fuel in an ablator of either CH with Ge doping, or Be with Cu.
Abstract: Point design targets have been specified for the initial ignition campaign on the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)]. The targets contain D-T fusion fuel in an ablator of either CH with Ge doping, or Be with Cu. These shells are imploded in a U or Au hohlraum with a peak radiation temperature set between 270 and 300 eV. Considerations determining the point design include laser-plasma interactions, hydrodynamic instabilities, laser operations, and target fabrication. Simulations were used to evaluate choices, and to define requirements and specifications. Simulation techniques and their experimental validation are summarized. Simulations were used to estimate the sensitivity of target performance to uncertainties and variations in experimental conditions. A formalism is described that evaluates margin for ignition, summarized in a parameter the Ignition Threshold Factor (ITF). Uncertainty and shot-to-shot variability in ITF are evaluated, and...

534 citations

Journal ArticleDOI
TL;DR: The National Ignition Campaign (NIC) as mentioned in this paper was a multi-institution effort established under the National Nuclear Security Administration of DOE in 2005, prior to the completion of the NIF in 2009.
Abstract: The National Ignition Campaign (NIC) was a multi-institution effort established under the National Nuclear Security Administration of DOE in 2005, prior to the completion of the National Ignition Facility (NIF) in 2009. The scope of the NIC was the planning and preparation for and the execution of the first 3 yr of ignition experiments (through the end of September 2012) as well as the development, fielding, qualification, and integration of the wide range of capabilities required for ignition. Besides the operation and optimization of the use of NIF, these capabilities included over 50 optical, x-ray, and nuclear diagnostic systems, target fabrication facilities, experimental platforms, and a wide range of NIF facility infrastructure. The goal of ignition experiments on the NIF is to achieve, for the first time, ignition and thermonuclear burn in the laboratory via inertial confinement fusion and to develop a platform for ignition and high energy density applications on the NIF. The goal of the NIC was to develop and integrate all of the capabilities required for a precision ignition campaign and, if possible, to demonstrate ignition and gain by the end of FY12. The goal of achieving ignition can be divided into three main challenges. The first challenge is defining specifications for the target, laser, and diagnostics with the understanding that not all ignition physics is fully understood and not all material properties are known. The second challenge is designing experiments to systematically remove these uncertainties. The third challenge is translating these experimental results into metrics designed to determine how well the experimental implosions have performed relative to expectations and requirements and to advance those metrics toward the conditions required for ignition. This paper summarizes the approach taken to address these challenges, along with the progress achieved to date and the challenges that remain. At project completion in 2009, NIF lacked almost all the diagnostics and infrastructure required for ignition experiments. About half of the 3 yr period covered in this review was taken up by the effort required to install and performance qualify the equipment and experimental platforms needed for ignition experiments. Ignition on the NIF is a grand challenge undertaking and the results presented here represent a snapshot in time on the path toward that goal. The path forward presented at the end of this review summarizes plans for the Ignition Campaign on the NIF, which were adopted at the end of 2012, as well as some of the key results obtained since the end of the NIC.

509 citations