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

Author

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

Abstract

A record fuel hot-spot pressure P[subscript hs] = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, LM15119ER (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance., United States. Department of Energy (DE-NA0001944)

Published
2017

2. Exploration of the Transition from the Hydrodynamiclike to the Strongly Kinetic Regime in Shock-Driven Implosions

Author

Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Rosenberg, Michael Jonathan, Rinderknecht, Hans George, Zylstra, Alex Bennett, Li, Chikang, Seguin, Fredrick Hampton, Sio, Hong Weng, Gatu Johnson, Maria, Frenje, Johan A., Petrasso, Richard D., Kagan, Grigory Alexandrovich, Hoffman, N. M., Amendt, P. A., Atzeni, S., Glebov, V. Yu., Stoeckl, C., Seka, W., Marshall, F. J., Delettrez, J. A., Sangster, T. C., Betti, R., Goncharov, V. N., Meyerhofer, D. D., Skupsky, S., Bellei, C., Pino, J., Wilks, S. C., Molvig, Kim, Nikroo, A., Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Rosenberg, Michael Jonathan, Rinderknecht, Hans George, Zylstra, Alex Bennett, Li, Chikang, Seguin, Fredrick Hampton, Sio, Hong Weng, Gatu Johnson, Maria, Frenje, Johan A., Petrasso, Richard D., Kagan, Grigory Alexandrovich, Hoffman, N. M., Amendt, P. A., Atzeni, S., Glebov, V. Yu., Stoeckl, C., Seka, W., Marshall, F. J., Delettrez, J. A., Sangster, T. C., Betti, R., Goncharov, V. N., Meyerhofer, D. D., Skupsky, S., Bellei, C., Pino, J., Wilks, S. C., Molvig, Kim, and Nikroo, A.

Abstract

Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D[superscript 3]He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ∼2 at 3.1 mg/cm[superscript 3] to a factor of 100 at 0.14 mg/cm[superscript 3]. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions., United States. Dept. of Energy (Grant DE-NA0001857), United States. Dept. of Energy (Grant DE-FC52-08NA28752), University of Rochester. Fusion Science Center (5-24431), National Laser User’s Facility (DE-NA0002035), University of Rochester. Laboratory for Laser Energetics (415935-G), Lawrence Livermore National Laboratory (B597367)

Published
2014

3. Implosion Experiments using Glass Ablators for Direct-Drive Inertial Confinement Fusion

Author

Massachusetts Institute of Technology. Plasma Science and Fusion Center, Seguin, Fredrick Hampton, Frenje, Johan A., Li, Chikang, Petrasso, Richard D., Smalyuk, V. A., Betti, R., Delettrez, J. A., Glebov, V. Yu., Meyerhofer, D. D., Radha, P. B., Regan, S. P., Sangster, T. C., Sanz, J., Seka, W., Stoecki, C., Yaakobi, B., Massachusetts Institute of Technology. Plasma Science and Fusion Center, Seguin, Fredrick Hampton, Frenje, Johan A., Li, Chikang, Petrasso, Richard D., Smalyuk, V. A., Betti, R., Delettrez, J. A., Glebov, V. Yu., Meyerhofer, D. D., Radha, P. B., Regan, S. P., Sangster, T. C., Sanz, J., Seka, W., Stoecki, C., and Yaakobi, B.

Abstract

Direct-drive implosions with 20-μm-thick glass shells were conducted on the Omega Laser Facility to test the performance of high-Z glass ablators for direct-drive, inertial confinement fusion. The x-ray signal caused by hot electrons generated by two-plasmon-decay instability was reduced by more than ~40× and hot-electron temperature by ~2× in the glass compared to plastic ablators at ignition-relevant drive intensities of ~1×10[superscript 15] W/cm[superscript 2], suggesting reduced target preheat. The measured absorption and compression were close to 1D predictions. The measured soft x-ray production in the spectral range of ~2 to 4 keV was ~2× to 3× lower than 1D predictions, indicating that the shell preheat caused by soft x-rays is less than predicted. A direct-drive-ignition design based on glass ablators is introduced., United States. Dept. of Energy. Office of Inertial Confinement Fusion (Cooperative Agreement No. DE-FC52-08NA28302), University of Rochester, New York State Energy Research and Development Authority

Published
2010

4. Demonstration of the Highest Deuterium-Tritium Areal Density Using Multiple-Picket Cryogenic Designs on OMEGA

Author

Massachusetts Institute of Technology. Plasma Science and Fusion Center, Petrasso, Richard D., Casey, Daniel Thomas, Frenje, Johan A., Goncharov, V. N., Sangster, T. C., Boehly, T. R., Hu, S. X., Igumenshchev, I. V., Marshall, F. J., McCrory, R. L., Meyerhofer, D. D., Radha, P. B., Seka, W., Skupsky, S., Stoeckl, C., Massachusetts Institute of Technology. Plasma Science and Fusion Center, Petrasso, Richard D., Casey, Daniel Thomas, Frenje, Johan A., Goncharov, V. N., Sangster, T. C., Boehly, T. R., Hu, S. X., Igumenshchev, I. V., Marshall, F. J., McCrory, R. L., Meyerhofer, D. D., Radha, P. B., Seka, W., Skupsky, S., and Stoeckl, C.

Abstract

The performance of triple-picket deuterium-tritium cryogenic target designs on the OMEGA Laser System [T.R. Boehly et al., Opt. Commun. 133, 495 (1997)] is reported. These designs facilitate control of shock heating in low-adiabat inertial confinement fusion targets. Areal densities up to 300 mg=cm[superscript 2] (the highest ever measured in cryogenic deuterium-tritium implosions) are inferred in the experiments with an implosion velocity ~3×10[superscript 7] cm=s driven at peak laser intensities of 8×10[superscript 14] W=cm[superscript 2]. Extension of these designs to ignition on the National Ignition Facility [J. A. Paisner et al., Laser FocusWorld 30, 75 (1994)] is presented., United States. Office of Inertial Confinement Fusion (Cooperative Agreement No. DE-FC52-08NA28302), University of Rochester, New York State Energy Research and Development Authority

Published
2010

5. Nonuniformly Driven Two-Plasmon-Decay Instability in Direct-Drive Implosions.

Author

Seka, W., Myatt, J. F., Short, R. W., Froula, D. H., Katz, J., Goncharov, V. N., and Igumenshchev, I. V.

Subjects
*PLASMONS (Physics), *EXCITON theory, *PLASMA waves, *PHONON-plasmon interactions, *PLASMA gases
Abstract

Half-harmonic emission spectra and images taken during directly driven implosions show that the two-plasmon decay (TPD) instability is driven nonuniformly over the target surface and that multibeam effects dominate this instability. The images show a spatially limited extent of the TPD instability. A prominent spectral feature is used to determine the electron temperature in the corona. Near threshold the temperatures agree with one-dimensional hydrodynamic predictions but exceed them by ∼10% above the TPD threshold. Two-dimensional hydrodynamic simulations indicate that a significant part (∼20%) of the laser intensity must be locally absorbed by the TPD instability (i.e., by collisional damping of the electron plasma waves) to maintain these temperature islands. [ABSTRACT FROM AUTHOR]

Published
2014
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6. Theory and measurements of convective Raman side scatter in inertial confinement fusion experiments.

Author

Michel, P., Rosenberg, M. J., Seka, W., Solodov, A. A., Short, R. W., Chapman, T., Goyon, C., Lemos, N., Hohenberger, M., Moody, J. D., Regan, S. P., and Myatt, J. F.

Subjects
*RAMAN scattering, *INERTIAL confinement fusion, *THOMSON scattering, *LIGHT scattering, *PLASMA density, *ELECTRON density
Abstract

Raman side scatter, whereby scattered light is resonant while propagating perpendicularly to a density gradient in a plasma, was identified experimentally in planar-target experiments at the National Ignition Facility at intensities orders of magnitudes below the threshold for absolute instability. We have derived a new theoretical description of convective Raman side scatter below the absolute threshold, validated by numerical simulations. We show that inertial confinement fusion experiments at full ignition scale, i.e., with mm-scale spot sizes and density scale lengths, are prone to increased coupling losses from Raman side scatter as the instability can extend from the absolute regime near the quarter-critical density to the convective regime at lower electron densities. [ABSTRACT FROM AUTHOR]

Published
2019
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7. Measurements of the Conduction-Zone Length and Mass Ablation Rate in Cryogenic Direct-Drive Implosions on OMEGA.

Author

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

Subjects
*CRYOGENICS, *ABSORPTION, *SORPTION, *LASERS, *ATOMIC physics
Abstract

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

Published
2015
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8. Gigabar Spherical Shock Generation on the OMEGA Laser.

Author

Nora, R., Theobald, W., Betti, R., Marshall, F. J., Michel, D. T., Seka, W., Yaakobi, B., Lafon, M., Stoeckl, C., Delettrez, J., Solodov, A. A., Casner, A., Reverdin, C., Ribeyre, X., Vallet, A., Peebles, J., Beg, F. N., and Wei, M. S.

Subjects
*HYDRODYNAMICS, *HEAT transfer, *FLUID dynamics, *COUPLING reactions (Chemistry), *HECK reaction, *TECHNOLOGY convergence
Abstract

This Letter presents the first e×perimental demonstration of the capability to launch shocks of severalhundred Mbar in spherical targets-a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using the temporal delay between the launching of the strong shock at the outer surface of the spherical target and the time when the shock converges at the center, the shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures e×ceeding 300 Mbar are inferred at absorbed laser intensities of ∼3 × 1015 W/cm2. The shock strength is shown to be significantly enhanced by the coupling of suprathermal electrons with a total converted energy of up to 8% of the incident laser energy. At the end of the laser pulse, the shock pressure is estimated to e×ceed ∼1 Gbar because of convergence effects. [ABSTRACT FROM AUTHOR]

Published
2015
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9. Exploration of the Transition from the Hydrodynamiclike to the Strongly Kinetic Regime in Shock-Driven Implosions.

Author

Rosenberg, M. J., Rinderknecht, H. G., Hoftman, N. M., Amendt, P. A., Atzeni, S., Zylstra, A. B., Li, C. K., Séguin, E. H., Sio, H., Gatu Johnson, M., Erenje, J. A., Petrasso, R. D., Glebov, V. Yu., Stoeckl, C., Seka, W., Marshall, E. J., Delettrez, J. A., Sangster, T. C., Betti, R., and Goncharov, V. N.

Subjects
*HYDRODYNAMICS, *KNUDSEN flow, *DIFFUSION, *IONS, *CALIBRATION
Abstract

Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ∼2 at 3.1 mg/cm3 to a factor of 100 at 0.14 mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion bum duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to gamer insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions. [ABSTRACT FROM AUTHOR]

Published
2014
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10. Laser-Beam Zooming to Mitigate Crossed-Beam Energy Losses in Direct-Drive Implosions.

Author

Igumenshchev, I. V., Froula, D. H., Edgell, D. H., Goncharov, V. N., Kessler, T. J., Marshall, F. J., McCrory, R. L., McKenty, P. W., Meyerhofer, D. D., Michel, D. T., Sangster, T. C., Seka, W., and Skupsky, S.

Subjects
*LASER recording, *ENERGY dissipation, *ENERGY transfer, *HYDRODYNAMICS, *FUSION (Phase transformation)
Abstract

Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by ~30%-40% after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain »1. [ABSTRACT FROM AUTHOR]

Published
2013
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11. Experimental Validation of the Two-Plasmon-Decay Common-Wave Process.

Author

Michel, D. T., Maximov, A. V., Short, R. W., Hu, S. X., Myatt, J. F., Seka, W., Solodov, A. A., Yaakobi, B., and Froula, D. H.

Subjects
*PLASMONS (Physics), *HOT carriers, *PLASMA instabilities, *LASER beams, *PREDICTION models, *PHYSICAL constants
Abstract

The energy in hot electrons produced by the two plasmon decay instability, in planar targets, is measured to be the same when driven by one or two laser beams and significantly reduced with four for a constant overlapped intensity on the OMEGA EP. This is caused by multiple beams sharing the same common electron-plasma wave. A model, consistent with the experimental results, predicts that multiple laser beams can only drive a resonant common two plasmon decay electron-plasma wave in the region of wave numbers bisecting the beams. In this region, the gain is proportional to the overlapped laser beam intensity. [ABSTRACT FROM AUTHOR]

Published
2012
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12. Saturation of the Two-Plasmon Decay Instability in Long-Scale-Length Plasmas Relevant to Direct-Drive Inertial Confinement Fusion.

Author

Froula, D. H., Yaakobi, B., Hu, S. X., Chang, P-Y., Craxton, R. S., Edgell, D. H., Follett, R., Michel, D. T., Myatt, J. F., Seka, W., Short, R. W., Solodov, A., and Stoeckl, C.

Subjects
*INERTIAL confinement fusion, *LASER beams, *ELECTRONS, *RADIOACTIVE decay, *NUCLEAR physics, *ELECTRON temperature
Abstract

Measurements of the hot-electron generation by the two-plasmon-decay instability are made in plasmas relevant to direct-drive inertial confinement fusion. Density-scale lengths of 400 jiim at ncr/4 in planar CH targets allowed the two-plasmon-decay instability to be driven to saturation for vacuum intensities above ∼3.5 X 1014 Wem-2. In the saturated regime, ∼1% of the laser energy is converted to hot electrons. The hot-electron temperature is measured to increase rapidly from 25 to 90 keV as the laser beam intensity is increased from 2 to 7 X 1014 Wem-2. This increase in the hot-electron temperature is compared with predictions from nonlinear Zakharov models. [ABSTRACT FROM AUTHOR]

Published
2012
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13. Increasing Hydrodynamic Efficiency by Reducing Cross-Beam Energy Transfer in Direct-Drive-Implosion Experiments.

Author

Froula, D. H., Igumenshchev, I. V., Michel, D. T., Edgell, D. H., Follett, R., Glebov, V. Yu., Goncharov, V. N., Kwiatkowski, J., Marshall, F. J., Radha, P. B., Seka, W., Sorce, C., Stagnitto, S., Stoeckl, C., and Sangster, T. C.

Subjects
*HYDRODYNAMICS, *ENERGY transfer, *PHYSICS experiments, *LASER beams, *ABSORPTION, *BIG bang theory, *SIMULATION methods & models
Abstract

A series of experiments to determine the optimum laser-beam radius by balancing the reduction of cross-beam energy transfer (CBET) with increased illumination nonuniformities shows that the hydro-dynamic efficiency is increased by ∼35%, which leads to a factor of 2.6 increase in the neutron yield when the laser-spot size is reduced by 20%. Over this range, the absorption is measured to increase by 15%, resulting in a 17% increase in the implosion velocity and a 10% earlier bang time. When reducing the ratio of laser-spot size to a target radius below 0.8, the rms amplitudes of the nonuniformities imposed by the smaller laser spots are measured at a convergence ratio of 2.5 to exceed 8 &mgr;m and the neutron yield saturates despite increasing absorbed energy, implosion velocity, and decreasing bang time. The results agree well with hydrodynamic simulations that include both nonlocal and CBET models. [ABSTRACT FROM AUTHOR]

Published
2012
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14. Amplification of light in a plasma by stimulated ion acoustic waves driven by multiple crossing pump beams.

Author

Kirkwood, R. K., Michel, P., London, R. A., Callahan, D., Meezan, N., Williams, E., Seka, W., Suter, L., Haynam, C., and Landen, O.

Subjects
*LASERS, *LIGHT amplifiers, *ION acoustic waves, *PLASMA waves, *RAMAN effect
Abstract

Experiments demonstrate the amplification of 351 nm laser light in a hot dense plasma similar to those in inertial confinement fusion ignition experiments. A seed beam interacts with one or two counter-propagating pump beams, each with an intensity of 1.2 x 1015 W/cm² at 351 nm, crossing the seed at 24.8° at the position where the flow is Mach 1, allowing resonant stimulation of ion acoustic waves. Results show that the energy and power transferred to the seed are increased with two pumps beyond the level that occurs with a single pump, demonstrating that, under conditions similar to ignition experiments where each beam has a low gain exponent, the total scatter produced by the multiple beams can be significantly larger than that of the individual beams. It is further demonstrated that the amplification is greatly reduced when the pump polarization is orthogonal to the seed, as expected from models of stimulated scatter. [ABSTRACT FROM AUTHOR]

Published
2011
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15. Direct Measurements of DT Fuel Preheat from Hot Electrons in Direct-Drive Inertial Confinement Fusion.

Author

Christopherson, A. R., Betti, R., Forrest, C. J., Howard, J., Theobald, W., Delettrez, J. A., Rosenberg, M. J., Solodov, A. A., Stoeckl, C., Patel, D., Gopalaswamy, V., Cao, D., Peebles, J. L., Edgell, D. H., Seka, W., Epstein, R., Wei, M. S., Johnson, M. Gatu, Simpson, R., and Regan, S. P.

Subjects
*HOT carriers, *INERTIAL confinement fusion, *LASER fusion, *HARD X-rays
Abstract

Hot electrons generated by laser-plasma instabilities degrade the performance of laser-fusion implosions by preheating the DT fuel and reducing core compression. The hot-electron energy deposition in the DT fuel has been directly measured for the first time by comparing the hard x-ray signals between DT-layered and mass-equivalent ablator-only implosions. The electron energy deposition profile in the fuel is inferred through dedicated experiments using Cu-doped payloads of varying thickness. The measured preheat energy accurately explains the areal-density degradation observed in many OMEGA implosions. This technique can be used to assess the viability of the direct-drive approach to laser fusion with respect to the scaling of hot-electron preheat with laser energy. [ABSTRACT FROM AUTHOR]

Published
2021
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16. Anomalous Absorption by the Two-Plasmon Decay Instability.

Author

Turnbull, D., Maximov, A. V., Edgell, D. H., Seka, W., Follett, R. K., Palastro, J. P., Cao, D., Goncharov, V. N., Stoeckl, C., and Froula, D. H.

Subjects
*ABSORPTION, *INERTIAL confinement fusion, *PLASMONS (Physics), *LASERS, *DENSITY
Abstract

Radiation-hydrodynamic simulations of directly driven fusion experiments at the Omega Laser Facility predict absorption accurately when targets are driven at low overlapped laser intensity. Discrepancies appear at increased intensity, however, with higher-than-expected laser absorption on target. Strong correlations with signatures of the two-plasmon decay (TPD) instability--including half-harmonic and hard-x-ray emission--indicate that TPD is responsible for this anomalous absorption. Scattered light data suggest that up to ≈30% of the laser power reaching quarter-critical density can be absorbed locally when the TPD threshold is exceeded. A scaling of absorption versus TPD threshold parameter was empirically determined and validated using the laser-plasma simulation environment code. [ABSTRACT FROM AUTHOR]

Published
2020
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17. Properties of hot-spot emission in a warm plastic-shell implosion on the OMEGA laser system.

Author

Shang, W. L., Stoeckl, C., Betti, R., Regan, S. P., Sangster, T. C., Hu, S. X., Christopherson, A., Gopalaswamy, V., Cao, D., Seka, W., Michel, D. T., Davis, A. K., Radha, P. B., Marshall, F. J., Epstein, R., and Solodov, A. A.

Subjects
*ENERGY transfer, *HOT spots (Astronomy)
Abstract

A warm plastic-shell implosion is performed on the OMEGA laser system. The measured corona plasma evolution and shell trajectory in the acceleration phase are reasonably simulated by the one-dimensional lilac simulation including the nonlocal and cross-beam energy transfer models. The results from analytical thin-shell model reproduce the time-dependent shell radius by lilac simulation and also the hot-spot x-ray-emissivity profile at stagnation predicted by spect3d. In the spect3d simulations within a clean implosion, a U-shaped hot-spot radius evolution can be observed with the Kirkpatrick-Baez microscope response (the photon energy is from 4 to 8 keV). However, a fading-away hot-spot radius evolution is measured in OMEGA warm plastic-shell implosion because of mixings. To recover the measured hot-spot x-ray emissivity profile at stagnation, a nonisobaric hot-spot model is built and the normalized hot-spot temperature, density, and pressure profiles (normalized to the corresponding target-center values) are obtained. [ABSTRACT FROM AUTHOR]

Published
2018
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18. First Observation of Cross-Beam Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion Implosions Using Wavelength Detuning at the National Ignition Facility.

Author

Marozas, J. A., Hohenberger, M., Rosenberg, M. J., Turnbull, D., Collins, T. J. B., Radha, P. B., McKenty, P. W., Zuegel, J. D., Marshall, F. J., Regan, S. P., Sangster, T. C., Seka, W., Campbell, E. M., Goncharov, V. N., Bowers, M. W., Di Nicola, J.-M. G., Erbert, G., MacGowan, B. J., Pelz, L. J., and Yang, S. T.

Subjects
*ENERGY transfer, *INERTIAL confinement fusion, *WAVELENGTHS
Abstract

Cross-beam energy transfer (CBET) results from two-beam energy exchange via seeded stimulated Brillouin scattering, which detrimentally reduces ablation pressure and implosion velocity in direct-drive inertial confinement fusion. Mitigating CBET is demonstrated for the first time in inertial-confinement implosions at the National Ignition Facility by detuning the laser-source wavelengths (±2.3 Å UV) of the interacting beams. We show that, in polar direct-drive, wavelength detuning increases the equatorial region velocity experimentally by 16% and alters the in-flight shell morphology. These experimental observations are consistent with design predictions of radiation-hydrodynamic simulations that indicate a 10% increase in the average ablation pressure. [ABSTRACT FROM AUTHOR]

Published
2018
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19. Origins and Scaling of Hot-Electron Preheat in Ignition-Scale Direct-Drive Inertial Confinement Fusion Experiments.

Author

Rosenberg, M. J., Solodov, A. A., Myatt, J. F., Seka, W., Michel, P., Hohenberger, M., Short, R. W., Epstein, R., Regan, S. P., Campbell, E. M., Chapman, T., Goyon, C., Ralph, J. E., Barrios, M. A., Moody, J. D., and Bates, J. W.

Subjects
*HOT carriers, *LASER-plasma interactions, *ELECTRON density
Abstract

Planar laser-plasma interaction (LPI) experiments at the National Ignition Facility (NIF) have allowed access for the first time to regimes of electron density scale length (~ 500 to 700 μm), electron temperature (~ 3 to 5 keV), and laser intensity (6 to 16 × 1014 W/cm²) that are relevant to direct-drive inertial confinement fusion ignition. Unlike in shorter-scale-length plasmas on OMEGA, scattered-light data on the NIF show that the near-quarter-critical LPI physics is dominated by stimulated Raman scattering (SRS) rather than by two-plasmon decay (TPD). This difference in regime is explained based on absolute SRS and TPD threshold considerations. SRS sidescatter tangential to density contours and other SRS mechanisms are observed. The fraction of laser energy converted to hot electrons is ~ 0.7% to 2.9%, consistent with observed levels of SRS. The intensity threshold for hot-electron production is assessed, and the use of a Si ablator slightly increases this threshold from ~ 4 × 1014 to ~ 6 × 1014 W/cm². These results have significant implications for mitigation of LPI hot-electron preheat in direct-drive ignition designs. [ABSTRACT FROM AUTHOR]

Published
2018
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20. Using Inertial Fusion Implosions to Measure the T+³He Fusion Cross Section at Nucleosynthesis-Relevant Energies.

Author

Zylstra, A. B., Herrmann, H. W., Johnson, M. Gatu, Kim, Y. H., Frenje, J. A., Hale, G., Li, C. K., Rubery, M., Paris, M., Bacher, A., Brune, C. R., Forrest, C., Glebov, V. Yu., Janezic, R., McNabb, D., Nikroo, A., Pino, J., Sangster, T. C., Séguin, F. H., and Seka, W.

Subjects
*INERTIAL confinement fusion, *NUCLEAR cross sections, *NUCLEOSYNTHESIS
Abstract

Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6Li in low-metallicity stars. Using high-energy-density plasmas we measure the T(³He,γ)6Li reaction rate, a candidate for anomalously high 6Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics. [ABSTRACT FROM AUTHOR]

Published
2016
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21. Experimental Evidence of the Collective Brillouin Scattering of Multiple Laser Beams Sharing Acoustic Waves.

Author

Neuville, C., Tassin, V., Pesme, D., Monteil, M.-C., Masson-Laborde, P.-E., Baccou, C., Fremerye, P., Philippe, F., Seytor, P., Teychenné, D., Seka, W., Katz, J., Bahr, R., and Depierreux, S.

Subjects
*BRILLOUIN scattering, *LASER beams, *SOUND waves
Abstract

The indirect-drive scheme to inertial confinement fusion uses a large number of laser beams arranged in a symmetric angular distribution. Collective laser plasma instabilities can therefore develop that couple all the incident laser waves located in a cone to the daughter wave growing along the cone symmetry axis [D. F. DuBois et al., Phys. Fluids B 4, 241 (1992)]. With complementary diagnostics of Thomson scattering and of the scattered light, we demonstrate the occurrence of collective stimulated Brillouin sidescattering driving collective acoustic waves in indirect-drive experiments. [ABSTRACT FROM AUTHOR]

Published
2016
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22. Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment.

Author

Abu-Shawareb H, Acree R, Adams P, Adams J, Addis B, Aden R, Adrian P, Afeyan BB, Aggleton M, Aghaian L, Aguirre A, Aikens D, Akre J, Albert F, Albrecht M, Albright BJ, Albritton J, Alcala J, Alday C, Alessi DA, Alexander N, Alfonso J, Alfonso N, Alger E, Ali SJ, Ali ZA, Allen A, Alley WE, Amala P, Amendt PA, Amick P, Ammula S, Amorin C, Ampleford DJ, Anderson RW, Anklam T, Antipa N, Appelbe B, Aracne-Ruddle C, Araya E, Archuleta TN, Arend M, Arnold P, Arnold T, Arsenlis A, Asay J, Atherton LJ, Atkinson D, Atkinson R, Auerbach JM, Austin B, Auyang L, Awwal AAS, Aybar N, Ayers J, Ayers S, Ayers T, Azevedo S, Bachmann B, Back CA, Bae J, Bailey DS, Bailey J, Baisden T, Baker KL, Baldis H, Barber D, Barberis M, Barker D, Barnes A, Barnes CW, Barrios MA, Barty C, Bass I, Batha SH, Baxamusa SH, Bazan G, Beagle JK, Beale R, Beck BR, Beck JB, Bedzyk M, Beeler RG, Beeler RG, Behrendt W, Belk L, Bell P, Belyaev M, Benage JF, Bennett G, Benedetti LR, Benedict LX, Berger RL, Bernat T, Bernstein LA, Berry B, Bertolini L, Besenbruch G, Betcher J, Bettenhausen R, Betti R, Bezzerides B, Bhandarkar SD, Bickel R, Biener J, Biesiada T, Bigelow K, Bigelow-Granillo J, Bigman V, Bionta RM, Birge NW, Bitter M, Black AC, Bleile R, Bleuel DL, Bliss E, Bliss E, Blue B, Boehly T, Boehm K, Boley CD, Bonanno R, Bond EJ, Bond T, Bonino MJ, Borden M, Bourgade JL, Bousquet J, Bowers J, Bowers M, Boyd R, Boyle D, Bozek A, Bradley DK, Bradley KS, Bradley PA, Bradley L, Brannon L, Brantley PS, Braun D, Braun T, Brienza-Larsen K, Briggs R, Briggs TM, Britten J, Brooks ED, Browning D, Bruhn MW, Brunner TA, Bruns H, Brunton G, Bryant B, Buczek T, Bude J, Buitano L, Burkhart S, Burmark J, Burnham A, Burr R, Busby LE, Butlin B, Cabeltis R, Cable M, Cabot WH, Cagadas B, Caggiano J, Cahayag R, Caldwell SE, Calkins S, Callahan DA, Calleja-Aguirre J, Camara L, Camp D, Campbell EM, Campbell JH, Carey B, Carey R, Carlisle K, Carlson L, Carman L, Carmichael J, Carpenter A, Carr C, Carrera JA, Casavant D, Casey A, Casey DT, Castillo A, Castillo E, Castor JI, Castro C, Caughey W, Cavitt R, Celeste J, Celliers PM, Cerjan C, Chandler G, Chang B, Chang C, Chang J, Chang L, Chapman R, Chapman TD, Chase L, Chen H, Chen H, Chen K, Chen LY, Cheng B, Chittenden J, Choate C, Chou J, Chrien RE, Chrisp M, Christensen K, Christensen M, Christiansen NS, Christopherson AR, Chung M, Church JA, Clark A, Clark DS, Clark K, Clark R, Claus L, Cline B, Cline JA, Cobble JA, Cochrane K, Cohen B, Cohen S, Collette MR, Collins GW, Collins LA, Collins TJB, Conder A, Conrad B, Conyers M, Cook AW, Cook D, Cook R, Cooley JC, Cooper G, Cope T, Copeland SR, Coppari F, Cortez J, Cox J, Crandall DH, Crane J, Craxton RS, Cray M, Crilly A, Crippen JW, Cross D, Cuneo M, Cuotts G, Czajka CE, Czechowicz D, Daly T, Danforth P, Danly C, Darbee R, Darlington B, Datte P, Dauffy L, Davalos G, Davidovits S, Davis P, Davis J, Dawson S, Day RD, Day TH, Dayton M, Deck C, Decker C, Deeney C, DeFriend KA, Deis G, Delamater ND, Delettrez JA, Demaret R, Demos S, Dempsey SM, Desjardin R, Desjardins T, Desjarlais MP, Dewald EL, DeYoreo J, Diaz S, Dimonte G, Dittrich TR, Divol L, Dixit SN, Dixon J, Do A, Dodd ES, Dolan D, Donovan A, Donovan M, Döppner T, Dorrer C, Dorsano N, Douglas MR, Dow D, Downie J, Downing E, Dozieres M, Draggoo V, Drake D, Drake RP, Drake T, Dreifuerst G, Drury O, DuBois DF, DuBois PF, Dunham G, Durocher M, Dylla-Spears R, Dymoke-Bradshaw AKL, Dzenitis B, Ebbers C, Eckart M, Eddinger S, Eder D, Edgell D, Edwards MJ, Efthimion P, Eggert JH, Ehrlich B, Ehrmann P, Elhadj S, Ellerbee C, Elliott NS, Ellison CL, Elsner F, Emerich M, Engelhorn K, England T, English E, Epperson P, Epstein R, Erbert G, Erickson MA, Erskine DJ, Erlandson A, Espinosa RJ, Estes C, Estabrook KG, Evans S, Fabyan A, Fair J, Fallejo R, Farmer N, Farmer WA, Farrell M, Fatherley VE, Fedorov M, Feigenbaum E, Fehrenbach T, Feit M, Felker B, Ferguson W, Fernandez JC, Fernandez-Panella A, Fess S, Field JE, Filip CV, Fincke JR, Finn T, Finnegan SM, Finucane RG, Fischer M, Fisher A, Fisher J, Fishler B, Fittinghoff D, Fitzsimmons P, Flegel M, Flippo KA, Florio J, Folta J, Folta P, Foreman LR, Forrest C, Forsman A, Fooks J, Foord M, Fortner R, Fournier K, Fratanduono DE, Frazier N, Frazier T, Frederick C, Freeman MS, Frenje J, Frey D, Frieders G, Friedrich S, Froula DH, Fry J, Fuller T, Gaffney J, Gales S, Le Galloudec B, Le Galloudec KK, Gambhir A, Gao L, Garbett WJ, Garcia A, Gates C, Gaut E, Gauthier P, Gavin Z, Gaylord J, Geddes CGR, Geissel M, Génin F, Georgeson J, Geppert-Kleinrath H, Geppert-Kleinrath V, Gharibyan N, Gibson J, Gibson C, Giraldez E, Glebov V, Glendinning SG, Glenn S, Glenzer SH, Goade S, Gobby PL, Goldman SR, Golick B, Gomez M, Goncharov V, Goodin D, Grabowski P, Grafil E, Graham P, Grandy J, Grasz E, Graziani FR, Greenman G, Greenough JA, Greenwood A, Gregori G, Green T, Griego JR, Grim GP, Grondalski J, Gross S, Guckian J, Guler N, Gunney B, Guss G, Haan S, Hackbarth J, Hackel L, Hackel R, Haefner C, Hagmann C, Hahn KD, Hahn S, Haid BJ, Haines BM, Hall BM, Hall C, Hall GN, Hamamoto M, Hamel S, Hamilton CE, Hammel BA, Hammer JH, Hampton G, Hamza A, Handler A, Hansen S, Hanson D, Haque R, Harding D, Harding E, Hares JD, Harris DB, Harte JA, Hartouni EP, Hatarik R, Hatchett S, Hauer AA, Havre M, Hawley R, Hayes J, Hayes J, Hayes S, Hayes-Sterbenz A, Haynam CA, Haynes DA, Headley D, Heal A, Heebner JE, Heerey S, Heestand GM, Heeter R, Hein N, Heinbockel C, Hendricks C, Henesian M, Heninger J, Henrikson J, Henry EA, Herbold EB, Hermann MR, Hermes G, Hernandez JE, Hernandez VJ, Herrmann MC, Herrmann HW, Herrera OD, Hewett D, Hibbard R, Hicks DG, Higginson DP, Hill D, Hill K, Hilsabeck T, Hinkel DE, Ho DD, Ho VK, Hoffer JK, Hoffman NM, Hohenberger M, Hohensee M, Hoke W, Holdener D, Holdener F, Holder JP, Holko B, Holunga D, Holzrichter JF, Honig J, Hoover D, Hopkins D, Berzak Hopkins LF, Hoppe M, Hoppe ML, Horner J, Hornung R, Horsfield CJ, Horvath J, Hotaling D, House R, Howell L, Hsing WW, Hu SX, Huang H, Huckins J, Hui H, Humbird KD, Hund J, Hunt J, Hurricane OA, Hutton M, Huynh KH, Inandan L, Iglesias C, Igumenshchev IV, Ivanovich I, Izumi N, Jackson M, Jackson J, Jacobs SD, James G, Jancaitis K, Jarboe J, Jarrott LC, Jasion D, Jaquez J, Jeet J, Jenei AE, Jensen J, Jimenez J, Jimenez R, Jobe D, Johal Z, Johns HM, Johnson D, Johnson MA, Gatu Johnson M, Johnson RJ, Johnson S, Johnson SA, Johnson T, Jones K, Jones O, Jones M, Jorge R, Jorgenson HJ, Julian M, Jun BI, Jungquist R, Kaae J, Kabadi N, Kaczala D, Kalantar D, Kangas K, Karasiev VV, Karasik M, Karpenko V, Kasarky A, Kasper K, Kauffman R, Kaufman MI, Keane C, Keaty L, Kegelmeyer L, Keiter PA, Kellett PA, Kellogg J, Kelly JH, Kemic S, Kemp AJ, Kemp GE, Kerbel GD, Kershaw D, Kerr SM, Kessler TJ, Key MH, Khan SF, Khater H, Kiikka C, Kilkenny J, Kim Y, Kim YJ, Kimko J, Kimmel M, Kindel JM, King J, Kirkwood RK, Klaus L, Klem D, Kline JL, Klingmann J, Kluth G, Knapp P, Knauer J, Knipping J, Knudson M, Kobs D, Koch J, Kohut T, Kong C, Koning JM, Koning P, Konior S, Kornblum H, Kot LB, Kozioziemski B, Kozlowski M, Kozlowski PM, Krammen J, Krasheninnikova NS, Krauland CM, Kraus B, Krauser W, Kress JD, Kritcher AL, Krieger E, Kroll JJ, Kruer WL, Kruse MKG, Kucheyev S, Kumbera M, Kumpan S, Kunimune J, Kur E, Kustowski B, Kwan TJT, Kyrala GA, Laffite S, Lafon M, LaFortune K, Lagin L, Lahmann B, Lairson B, Landen OL, Land T, Lane M, Laney D, Langdon AB, Langenbrunner J, Langer SH, Langro A, Lanier NE, Lanier TE, Larson D, Lasinski BF, Lassle D, LaTray D, Lau G, Lau N, Laumann C, Laurence A, Laurence TA, Lawson J, Le HP, Leach RR, Leal L, Leatherland A, LeChien K, Lechleiter B, Lee A, Lee M, Lee T, Leeper RJ, Lefebvre E, Leidinger JP, LeMire B, Lemke RW, Lemos NC, Le Pape S, Lerche R, Lerner S, Letts S, Levedahl K, Lewis T, Li CK, Li H, Li J, Liao W, Liao ZM, Liedahl D, Liebman J, Lindford G, Lindman EL, Lindl JD, Loey H, London RA, Long F, Loomis EN, Lopez FE, Lopez H, Losbanos E, Loucks S, Lowe-Webb R, Lundgren E, Ludwigsen AP, Luo R, Lusk J, Lyons R, Ma T, Macallop Y, MacDonald MJ, MacGowan BJ, Mack JM, Mackinnon AJ, MacLaren SA, MacPhee AG, Magelssen GR, Magoon J, Malone RM, Malsbury T, Managan R, Mancini R, Manes K, Maney D, Manha D, Mannion OM, Manuel AM, Manuel MJ, Mapoles E, Mara G, Marcotte T, Marin E, Marinak MM, Mariscal DA, Mariscal EF, Marley EV, Marozas JA, Marquez R, Marshall CD, Marshall FJ, Marshall M, Marshall S, Marticorena J, Martinez JI, Martinez D, Maslennikov I, Mason D, Mason RJ, Masse L, Massey W, Masson-Laborde PE, Masters ND, Mathisen D, Mathison E, Matone J, Matthews MJ, Mattoon C, Mattsson TR, Matzen K, Mauche CW, Mauldin M, McAbee T, McBurney M, Mccarville T, McCrory RL, McEvoy AM, McGuffey C, Mcinnis M, McKenty P, McKinley MS, McLeod JB, McPherson A, Mcquillan B, Meamber M, Meaney KD, Meezan NB, Meissner R, Mehlhorn TA, Mehta NC, Menapace J, Merrill FE, Merritt BT, Merritt EC, Meyerhofer DD, Mezyk S, Mich RJ, Michel PA, Milam D, Miller C, Miller D, Miller DS, Miller E, Miller EK, Miller J, Miller M, Miller PE, Miller T, Miller W, Miller-Kamm V, Millot M, Milovich JL, Minner P, Miquel JL, Mitchell S, Molvig K, Montesanti RC, Montgomery DS, Monticelli M, Montoya A, Moody JD, Moore AS, Moore E, Moran M, Moreno JC, Moreno K, Morgan BE, Morrow T, Morton JW, Moses E, Moy K, Muir R, Murillo MS, Murray JE, Murray JR, Munro DH, Murphy TJ, Munteanu FM, Nafziger J, Nagayama T, Nagel SR, Nast R, Negres RA, Nelson A, Nelson D, Nelson J, Nelson S, Nemethy S, Neumayer P, Newman K, Newton M, Nguyen H, Di Nicola JG, Di Nicola P, Niemann C, Nikroo A, Nilson PM, Nobile A, Noorai V, Nora RC, Norton M, Nostrand M, Note V, Novell S, Nowak PF, Nunez A, Nyholm RA, O'Brien M, Oceguera A, Oertel JA, Oesterle AL, Okui J, Olejniczak B, Oliveira J, Olsen P, Olson B, Olson K, Olson RE, Opachich YP, Orsi N, Orth CD, Owen M, Padalino S, Padilla E, Paguio R, Paguio S, Paisner J, Pajoom S, Pak A, Palaniyappan S, Palma K, Pannell T, Papp F, Paras D, Parham T, Park HS, Pasternak A, Patankar S, Patel MV, Patel PK, Patterson R, Patterson S, Paul B, Paul M, Pauli E, Pearce OT, Pearcy J, Pedretti A, Pedrotti B, Peer A, Pelz LJ, Penetrante B, Penner J, Perez A, Perkins LJ, Pernice E, Perry TS, Person S, Petersen D, Petersen T, Peterson DL, Peterson EB, Peterson JE, Peterson JL, Peterson K, Peterson RR, Petrasso RD, Philippe F, Phillion D, Phipps TJ, Piceno E, Pickworth L, Ping Y, Pino J, Piston K, Plummer R, Pollack GD, Pollaine SM, Pollock BB, Ponce D, Ponce J, Pontelandolfo J, Porter JL, Post J, Poujade O, Powell C, Powell H, Power G, Pozulp M, Prantil M, Prasad M, Pratuch S, Price S, Primdahl K, Prisbrey S, Procassini R, Pruyne A, Pudliner B, Qiu SR, Quan K, Quinn M, Quintenz J, Radha PB, Rainer F, Ralph JE, Raman KS, Raman R, Rambo PW, Rana S, Randewich A, Rardin D, Ratledge M, Ravelo N, Ravizza F, Rayce M, Raymond A, Raymond B, Reed B, Reed C, Regan S, Reichelt B, Reis V, Reisdorf S, Rekow V, Remington BA, Rendon A, Requieron W, Rever M, Reynolds H, Reynolds J, Rhodes J, Rhodes M, Richardson MC, Rice B, Rice NG, Rieben R, Rigatti A, Riggs S, Rinderknecht HG, Ring K, Riordan B, Riquier R, Rivers C, Roberts D, Roberts V, Robertson G, Robey HF, Robles J, Rocha P, Rochau G, Rodriguez J, Rodriguez S, Rosen MD, Rosenberg M, Ross G, Ross JS, Ross P, Rouse J, Rovang D, Rubenchik AM, Rubery MS, Ruiz CL, Rushford M, Russ B, Rygg JR, Ryujin BS, Sacks RA, Sacks RF, Saito K, Salmon T, Salmonson JD, Sanchez J, Samuelson S, Sanchez M, Sangster C, Saroyan A, Sater J, Satsangi A, Sauers S, Saunders R, Sauppe JP, Sawicki R, Sayre D, Scanlan M, Schaffers K, Schappert GT, Schiaffino S, Schlossberg DJ, Schmidt DW, Schmit PF, Smidt JM, Schneider DHG, Schneider MB, Schneider R, Schoff M, Schollmeier M, Schroeder CR, Schrauth SE, Scott HA, Scott I, Scott JM, Scott RHH, Scullard CR, Sedillo T, Seguin FH, Seka W, Senecal J, Sepke SM, Seppala L, Sequoia K, Severyn J, Sevier JM, Sewell N, Seznec S, Shah RC, Shamlian J, Shaughnessy D, Shaw M, Shaw R, Shearer C, Shelton R, Shen N, Sherlock MW, Shestakov AI, Shi EL, Shin SJ, Shingleton N, Shmayda W, Shor M, Shoup M, Shuldberg C, Siegel L, Silva FJ, Simakov AN, Sims BT, Sinars D, Singh P, Sio H, Skulina K, Skupsky S, Slutz S, Sluyter M, Smalyuk VA, Smauley D, Smeltser RM, Smith C, Smith I, Smith J, Smith L, Smith R, Smith R, Schölmerich M, Sohn R, Sommer S, Sorce C, Sorem M, Soures JM, Spaeth ML, Spears BK, Speas S, Speck D, Speck R, Spears J, Spinka T, Springer PT, Stadermann M, Stahl B, Stahoviak J, Stanley J, Stanton LG, Steele R, Steele W, Steinman D, Stemke R, Stephens R, Sterbenz S, Sterne P, Stevens D, Stevers J, Still CH, Stoeckl C, Stoeffl W, Stolken JS, Stolz C, Storm E, Stone G, Stoupin S, Stout E, Stowers I, Strauser R, Streckart H, Streit J, Strozzi DJ, Stutz J, Summers L, Suratwala T, Sutcliffe G, Suter LJ, Sutton SB, Svidzinski V, Swadling G, Sweet W, Szoke A, Tabak M, Takagi M, Tambazidis A, Tang V, Taranowski M, Taylor LA, Telford S, Theobald W, Thi M, Thomas A, Thomas CA, Thomas I, Thomas R, Thompson IJ, Thongstisubskul A, Thorsness CB, Tietbohl G, Tipton RE, Tobin M, Tomlin N, Tommasini R, Toreja AJ, Torres J, Town RPJ, Townsend S, Trenholme J, Trivelpiece A, Trosseille C, Truax H, Trummer D, Trummer S, Truong T, Tubbs D, Tubman ER, Tunnell T, Turnbull D, Turner RE, Ulitsky M, Upadhye R, Vaher JL, VanArsdall P, VanBlarcom D, Vandenboomgaerde M, VanQuinlan R, Van Wonterghem BM, Varnum WS, Velikovich AL, Vella A, Verdon CP, Vermillion B, Vernon S, Vesey R, Vickers J, Vignes RM, Visosky M, Vocke J, Volegov PL, Vonhof S, Von Rotz R, Vu HX, Vu M, Wall D, Wall J, Wallace R, Wallin B, Walmer D, Walsh CA, Walters CF, Waltz C, Wan A, Wang A, Wang Y, Wark JS, Warner BE, Watson J, Watt RG, Watts P, Weaver J, Weaver RP, Weaver S, Weber CR, Weber P, Weber SV, Wegner P, Welday B, Welser-Sherrill L, Weiss K, Wharton KB, Wheeler GF, Whistler W, White RK, Whitley HD, Whitman P, Wickett ME, Widmann K, Widmayer C, Wiedwald J, Wilcox R, Wilcox S, Wild C, Wilde BH, Wilde CH, Wilhelmsen K, Wilke MD, Wilkens H, Wilkins P, Wilks SC, Williams EA, Williams GJ, Williams W, Williams WH, Wilson DC, Wilson B, Wilson E, Wilson R, Winters S, Wisoff PJ, Wittman M, Wolfe J, Wong A, Wong KW, Wong L, Wong N, Wood R, Woodhouse D, Woodruff J, Woods DT, Woods S, Woodworth BN, Wooten E, Wootton A, Work K, Workman JB, Wright J, Wu M, Wuest C, Wysocki FJ, Xu H, Yamaguchi M, Yang B, Yang ST, Yatabe J, Yeamans CB, Yee BC, Yi SA, Yin L, Young B, Young CS, Young CV, Young P, Youngblood K, Yu J, Zacharias R, Zagaris G, Zaitseva N, Zaka F, Ze F, Zeiger B, Zika M, Zimmerman GB, Zobrist T, Zuegel JD, and Zylstra AB

Abstract

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Published
2024
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23. Hot-electron preheat and mitigation in polar-direct-drive experiments at the National Ignition Facility.

Author

Solodov AA, Rosenberg MJ, Stoeckl M, Christopherson AR, Betti R, Radha PB, Stoeckl C, Hohenberger M, Bachmann B, Epstein R, Follett RK, Seka W, Myatt JF, Michel P, Regan SP, Palastro JP, Froula DH, Campbell EM, and Goncharov VN

Abstract

Target preheat by superthermal electrons from laser-plasma instabilities is a major obstacle to achieving thermonuclear ignition via direct-drive inertial confinement fusion at the National Ignition Facility (NIF). Polar-direct-drive surrogate plastic implosion experiments were performed on the NIF to quantify preheat levels at an ignition-relevant scale and develop mitigation strategies. The experiments were used to infer the hot-electron temperature, energy fraction, and divergence, and to directly measure the spatial hot-electron energy deposition profile inside the imploding shell. Silicon layers buried in the ablator are shown to mitigate the growth of laser-plasma instabilities and reduce preheat, providing a promising path forward for ignition designs at an on-target intensity of about 10^{15}W/cm^{2}.

Published
2022
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24. Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment.

Author

Abu-Shawareb H, Acree R, Adams P, Adams J, Addis B, Aden R, Adrian P, Afeyan BB, Aggleton M, Aghaian L, Aguirre A, Aikens D, Akre J, Albert F, Albrecht M, Albright BJ, Albritton J, Alcala J, Alday C, Alessi DA, Alexander N, Alfonso J, Alfonso N, Alger E, Ali SJ, Ali ZA, Alley WE, Amala P, Amendt PA, Amick P, Ammula S, Amorin C, Ampleford DJ, Anderson RW, Anklam T, Antipa N, Appelbe B, Aracne-Ruddle C, Araya E, Arend M, Arnold P, Arnold T, Asay J, Atherton LJ, Atkinson D, Atkinson R, Auerbach JM, Austin B, Auyang L, Awwal AS, Ayers J, Ayers S, Ayers T, Azevedo S, Bachmann B, Back CA, Bae J, Bailey DS, Bailey J, Baisden T, Baker KL, Baldis H, Barber D, Barberis M, Barker D, Barnes A, Barnes CW, Barrios MA, Barty C, Bass I, Batha SH, Baxamusa SH, Bazan G, Beagle JK, Beale R, Beck BR, Beck JB, Bedzyk M, Beeler RG, Beeler RG, Behrendt W, Belk L, Bell P, Belyaev M, Benage JF, Bennett G, Benedetti LR, Benedict LX, Berger R, Bernat T, Bernstein LA, Berry B, Bertolini L, Besenbruch G, Betcher J, Bettenhausen R, Betti R, Bezzerides B, Bhandarkar SD, Bickel R, Biener J, Biesiada T, Bigelow K, Bigelow-Granillo J, Bigman V, Bionta RM, Birge NW, Bitter M, Black AC, Bleile R, Bleuel DL, Bliss E, Bliss E, Blue B, Boehly T, Boehm K, Boley CD, Bonanno R, Bond EJ, Bond T, Bonino MJ, Borden M, Bourgade JL, Bousquet J, Bowers J, Bowers M, Boyd R, Bozek A, Bradley DK, Bradley KS, Bradley PA, Bradley L, Brannon L, Brantley PS, Braun D, Braun T, Brienza-Larsen K, Briggs TM, Britten J, Brooks ED, Browning D, Bruhn MW, Brunner TA, Bruns H, Brunton G, Bryant B, Buczek T, Bude J, Buitano L, Burkhart S, Burmark J, Burnham A, Burr R, Busby LE, Butlin B, Cabeltis R, Cable M, Cabot WH, Cagadas B, Caggiano J, Cahayag R, Caldwell SE, Calkins S, Callahan DA, Calleja-Aguirre J, Camara L, Camp D, Campbell EM, Campbell JH, Carey B, Carey R, Carlisle K, Carlson L, Carman L, Carmichael J, Carpenter A, Carr C, Carrera JA, Casavant D, Casey A, Casey DT, Castillo A, Castillo E, Castor JI, Castro C, Caughey 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Kritcher AL, Krieger E, Kroll JJ, Kruer WL, Kruse MKG, Kucheyev S, Kumbera M, Kumpan S, Kunimune J, Kustowski B, Kwan TJT, Kyrala GA, Laffite S, Lafon M, LaFortune K, Lahmann B, Lairson B, Landen OL, Langenbrunner J, Lagin L, Land T, Lane M, Laney D, Langdon AB, Langer SH, Langro A, Lanier NE, Lanier TE, Larson D, Lasinski BF, Lassle D, LaTray D, Lau G, Lau N, Laumann C, Laurence A, Laurence TA, Lawson J, Le HP, Leach RR, Leal L, Leatherland A, LeChien K, Lechleiter B, Lee A, Lee M, Lee T, Leeper RJ, Lefebvre E, Leidinger JP, LeMire B, Lemke RW, Lemos NC, Le Pape S, Lerche R, Lerner S, Letts S, Levedahl K, Lewis T, Li CK, Li H, Li J, Liao W, Liao ZM, Liedahl D, Liebman J, Lindford G, Lindman EL, Lindl JD, Loey H, London RA, Long F, Loomis EN, Lopez FE, Lopez H, Losbanos E, Loucks S, Lowe-Webb R, Lundgren E, Ludwigsen AP, Luo R, Lusk J, Lyons R, Ma T, Macallop Y, MacDonald MJ, MacGowan BJ, Mack JM, Mackinnon AJ, MacLaren SA, MacPhee AG, Magelssen GR, Magoon J, Malone RM, Malsbury T, 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Person S, Petersen D, Petersen T, Peterson DL, Peterson EB, Peterson JE, Peterson JL, Peterson K, Peterson RR, Petrasso RD, Philippe F, Phipps TJ, Piceno E, Ping Y, Pickworth L, Pino J, Plummer R, Pollack GD, Pollaine SM, Pollock BB, Ponce D, Ponce J, Pontelandolfo J, Porter JL, Post J, Poujade O, Powell C, Powell H, Power G, Pozulp M, Prantil M, Prasad M, Pratuch S, Price S, Primdahl K, Prisbrey S, Procassini R, Pruyne A, Pudliner B, Qiu SR, Quan K, Quinn M, Quintenz J, Radha PB, Rainer F, Ralph JE, Raman KS, Raman R, Rambo P, Rana S, Randewich A, Rardin D, Ratledge M, Ravelo N, Ravizza F, Rayce M, Raymond A, Raymond B, Reed B, Reed C, Regan S, Reichelt B, Reis V, Reisdorf S, Rekow V, Remington BA, Rendon A, Requieron W, Rever M, Reynolds H, Reynolds J, Rhodes J, Rhodes M, Richardson MC, Rice B, Rice NG, Rieben R, Rigatti A, Riggs S, Rinderknecht HG, Ring K, Riordan B, Riquier R, Rivers C, Roberts D, Roberts V, Robertson G, Robey HF, Robles J, Rocha P, Rochau G, Rodriguez J, Rodriguez S, Rosen M, Rosenberg M, Ross G, Ross JS, Ross P, Rouse J, Rovang D, Rubenchik AM, Rubery MS, Ruiz CL, Rushford M, Russ B, Rygg JR, Ryujin BS, Sacks RA, Sacks RF, Saito K, Salmon T, Salmonson JD, Sanchez J, Samuelson S, Sanchez M, Sangster C, Saroyan A, Sater J, Satsangi A, Sauers S, Saunders R, Sauppe JP, Sawicki R, Sayre D, Scanlan M, Schaffers K, Schappert GT, Schiaffino S, Schlossberg DJ, Schmidt DW, Schmitt MJ, Schneider DHG, Schneider MB, Schneider R, Schoff M, Schollmeier M, Schölmerich M, Schroeder CR, Schrauth SE, Scott HA, Scott I, Scott JM, Scott RHH, Scullard CR, Sedillo T, Seguin FH, Seka W, Senecal J, Sepke SM, Seppala L, Sequoia K, Severyn J, Sevier JM, Sewell N, Seznec S, Shah RC, Shamlian J, Shaughnessy D, Shaw M, Shaw R, Shearer C, Shelton R, Shen N, Sherlock MW, Shestakov AI, Shi EL, Shin SJ, Shingleton N, Shmayda W, Shor M, Shoup M, Shuldberg C, Siegel L, Silva FJ, Simakov AN, Sims BT, Sinars D, Singh P, Sio H, Skulina K, Skupsky S, Slutz S, Sluyter M, Smalyuk VA, Smauley D, Smeltser RM, Smith C, Smith I, Smith J, Smith L, Smith R, Sohn R, Sommer S, Sorce C, Sorem M, Soures JM, Spaeth ML, Spears BK, Speas S, Speck D, Speck R, Spears J, Spinka T, Springer PT, Stadermann M, Stahl B, Stahoviak J, Stanton LG, Steele R, Steele W, Steinman D, Stemke R, Stephens R, Sterbenz S, Sterne P, Stevens D, Stevers J, Still CB, Stoeckl C, Stoeffl W, Stolken JS, Stolz C, Storm E, Stone G, Stoupin S, Stout E, Stowers I, Strauser R, Streckart H, Streit J, Strozzi DJ, Suratwala T, Sutcliffe G, Suter LJ, Sutton SB, Svidzinski V, Swadling G, Sweet W, Szoke A, Tabak M, Takagi M, Tambazidis A, Tang V, Taranowski M, Taylor LA, Telford S, Theobald W, Thi M, Thomas A, Thomas CA, Thomas I, Thomas R, Thompson IJ, Thongstisubskul A, Thorsness CB, Tietbohl G, Tipton RE, Tobin M, Tomlin N, Tommasini R, Toreja AJ, Torres J, Town RPJ, Townsend S, Trenholme J, Trivelpiece A, Trosseille C, Truax H, Trummer D, Trummer S, Truong T, Tubbs D, Tubman ER, Tunnell T, Turnbull D, Turner RE, Ulitsky M, Upadhye R, Vaher JL, VanArsdall P, VanBlarcom D, Vandenboomgaerde M, VanQuinlan R, Van Wonterghem BM, Varnum WS, Velikovich AL, Vella A, Verdon CP, Vermillion B, Vernon S, Vesey R, Vickers J, Vignes RM, Visosky M, Vocke J, Volegov PL, Vonhof S, Von Rotz R, Vu HX, Vu M, Wall D, Wall J, Wallace R, Wallin B, Walmer D, Walsh CA, Walters CF, Waltz C, Wan A, Wang A, Wang Y, Wark JS, Warner BE, Watson J, Watt RG, Watts P, Weaver J, Weaver RP, Weaver S, Weber CR, Weber P, Weber SV, Wegner P, Welday B, Welser-Sherrill L, Weiss K, Widmann K, Wheeler GF, Whistler W, White RK, Whitley HD, Whitman P, Wickett ME, Widmayer C, Wiedwald J, Wilcox R, Wilcox S, Wild C, Wilde BH, Wilde CH, Wilhelmsen K, Wilke MD, Wilkens H, Wilkins P, Wilks SC, Williams EA, Williams GJ, Williams W, Williams WH, Wilson DC, Wilson B, Wilson E, Wilson R, Winters S, Wisoff J, Wittman M, Wolfe J, Wong A, Wong KW, Wong L, Wong N, Wood R, Woodhouse D, Woodruff J, Woods DT, Woods S, Woodworth BN, Wooten E, Wootton A, Work K, Workman JB, Wright J, Wu M, Wuest C, Wysocki FJ, Xu H, Yamaguchi M, Yang B, Yang ST, Yatabe J, Yeamans CB, Yee BC, Yi SA, Yin L, Young B, Young CS, Young CV, Young P, Youngblood K, Zacharias R, Zagaris G, Zaitseva N, Zaka F, Ze F, Zeiger B, Zika M, Zimmerman GB, Zobrist T, Zuegel JD, and Zylstra AB

Abstract

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Published
2022
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25. Experimental Investigation of the Collective Raman Scattering of Multiple Laser Beams in Inhomogeneous Plasmas.

Author

Depierreux S, Neuville C, Baccou C, Tassin V, Casanova M, Masson-Laborde PE, Borisenko N, Orekhov A, Colaitis A, Debayle A, Duchateau G, Heron A, Huller S, Loiseau P, Nicolaï P, Pesme D, Riconda C, Tran G, Bahr R, Katz J, Stoeckl C, Seka W, Tikhonchuk V, and Labaune C

Abstract

Experiments have been performed evidencing significant stimulated Raman sidescattering (SRS) at large angles from the density gradient. This was achieved in long scale-length high-temperature plasmas in which two beams couple to the same scattered electromagnetic wave further demonstrating for the first time this multiple-beam collective SRS interaction. The collective nature of the coupling and the amplification at large angles from the density gradient increase the global SRS losses and produce light scattered in novel directions out of the planes of incidence of the beams. These findings obtained in plasmas conditions relevant of inertial confinement fusion experiments similarly apply to the more complex geometry of these experiments where anomalously large levels of SRS were measured.

Published
2016
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26. Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA.

Author

Regan SP, Goncharov VN, Igumenshchev IV, Sangster TC, Betti R, Bose A, Boehly TR, Bonino MJ, Campbell EM, Cao D, Collins TJ, Craxton RS, Davis AK, Delettrez JA, Edgell DH, Epstein R, Forrest CJ, Frenje JA, Froula DH, Gatu Johnson M, Glebov VY, Harding DR, Hohenberger M, Hu SX, Jacobs-Perkins D, Janezic R, Karasik M, Keck RL, Kelly JH, Kessler TJ, Knauer JP, Kosc TZ, Loucks SJ, Marozas JA, Marshall FJ, McCrory RL, McKenty PW, Meyerhofer DD, Michel DT, Myatt JF, Obenschain SP, Petrasso RD, Radha PB, Rice B, Rosenberg MJ, Schmitt AJ, Schmitt MJ, Seka W, Shmayda WT, Shoup MJ, Shvydky A, Skupsky S, Solodov AA, Stoeckl C, Theobald W, Ulreich J, Wittman MD, Woo KM, Yaakobi B, and Zuegel JD

Abstract

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

Published
2016
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27. Velocity and timing of multiple spherically converging shock waves in liquid deuterium.

Author

Boehly TR, Goncharov VN, Seka W, Barrios MA, Celliers PM, Hicks DG, Collins GW, Hu SX, Marozas JA, and Meyerhofer DD

Abstract

The fuel entropy and required drive energy for an inertial confinement fusion implosion are set by a sequence of shocks that must be precisely timed to achieve ignition. This Letter reports measurements of multiple spherical shock waves in liquid deuterium that facilitate timing inertial confinement fusion shocks to the required precision. These experiments produced the highest shock velocity observed in liquid deuterium (U(s) = 135  km/s at ∼2500  GPa) and also the first observation of convergence effects on the shock velocity. Simulations model the shock-timing results well when a nonlocal transport model is used in the coronal plasma.

Published
2011
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28. Implosion experiments using glass ablators for direct-drive inertial confinement fusion.

Author

Smalyuk VA, Betti R, Delettrez JA, Glebov VY, Meyerhofer DD, Radha PB, Regan SP, Sangster TC, Sanz J, Seka W, Stoeckl C, Yaakobi B, Frenje JA, Li CK, Petrasso RD, and Séguin FH

Abstract

Direct-drive implosions with 20-microm-thick glass shells were conducted on the Omega Laser Facility to test the performance of high-Z glass ablators for direct-drive, inertial confinement fusion. The x-ray signal caused by hot electrons generated by two-plasmon-decay instability was reduced by more than approximately 40x and hot-electron temperature by approximately 2x in the glass compared to plastic ablators at ignition-relevant drive intensities of approximately 1x10(15) W/cm2, suggesting reduced target preheat. The measured absorption and compression were close to 1D predictions. The measured soft x-ray production in the spectral range of approximately 2 to 4 keV was approximately 2x to 3x lower than 1D predictions, indicating that the shell preheat caused by soft x-rays is less than predicted. A direct-drive-ignition design based on glass ablators is introduced.

Published
2010
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29. Demonstration of the highest deuterium-tritium areal density using multiple-picket cryogenic designs on OMEGA.

Author

Goncharov VN, Sangster TC, Boehly TR, Hu SX, Igumenshchev IV, Marshall FJ, McCrory RL, Meyerhofer DD, Radha PB, Seka W, Skupsky S, Stoeckl C, Casey DT, Frenje JA, and Petrasso RD

Abstract

The performance of triple-picket deuterium-tritium cryogenic target designs on the OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)] is reported. These designs facilitate control of shock heating in low-adiabat inertial confinement fusion targets. Areal densities up to 300 mg/cm2 (the highest ever measured in cryogenic deuterium-tritium implosions) are inferred in the experiments with an implosion velocity approximately 3x10(7) cm/s driven at peak laser intensities of 8x10(14) W/cm2. Extension of these designs to ignition on the National Ignition Facility [J. A. Paisner, Laser Focus World 30, 75 (1994)] is presented.

Published
2010
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30. Role of hot-electron preheating in the compression of direct-drive imploding targets with cryogenic D2 ablators.

Author

Smalyuk VA, Shvarts D, Betti R, Delettrez JA, Edgell DH, Glebov VY, Goncharov VN, McCrory RL, Meyerhofer DD, Radha PB, Regan SP, Sangster TC, Seka W, Skupsky S, Stoeckl C, Yaakobi B, Frenje JA, Li CK, Petrasso RD, and Séguin FH

Abstract

The compression of direct-drive, spherical implosions is studied using cryogenic D2 targets on the 60-beam, 351-nm OMEGA laser with intensities ranging from approximately 3x10(14) to approximately 1x10(15) W/cm2. The hard-x-ray signal from hot electrons generated by laser-plasma instabilities increases with laser intensity, while the areal density decreases. Mitigating hot-electron production, by reducing the laser intensity to approximately 3x10(14) W/cm2, results in areal density of the order of approximately 140 mg/cm2, in good agreement with 1D simulations. These results will be considered in future direct-drive-ignition designs.

Published
2008
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31. High-areal-density fuel assembly in direct-drive cryogenic implosions.

Author

Sangster TC, Goncharov VN, Radha PB, Smalyuk VA, Betti R, Craxton RS, Delettrez JA, Edgell DH, Glebov VY, Harding DR, Jacobs-Perkins D, Knauer JP, Marshall FJ, McCrory RL, McKenty PW, Meyerhofer DD, Regan SP, Seka W, Short RW, Skupsky S, Soures JM, Stoeckl C, Yaakobi B, Shvarts D, Frenje JA, Li CK, Petrasso RD, and Séguin FH

Abstract

The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)10.1016/S0030-4018(96)00325-2]. Neutron-averaged areal densities of 202+/-7 mg/cm2 and 182+/-7 mg/cm2 (corresponding to estimated peak fuel densities in excess of 100 g/cm3) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuel adiabat can be accurately controlled under ignition-relevant conditions.

Published
2008
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32. Intensity limits for propagation of 0.527 microm laser beams through large-scale-length plasmas for inertial confinement fusion.

Author

Niemann C, Divol L, Froula DH, Gregori G, Jones O, Kirkwood RK, Mackinnon AJ, Meezan NB, Moody JD, Sorce C, Suter LJ, Bahr R, Seka W, and Glenzer SH

Abstract

We have established the intensity limits for propagation of a frequency-doubled (2omega, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10(14) W/cm(2) and a strong reduction at intensities up to 10(15) W/cm(2) due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments.

Published
2005
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33. Effects of nonuniform illumination on implosion asymmetry in direct-drive inertial confinement fusion.

Author

Li CK, Séguin FH, Frenje JA, Petrasso RD, Delettrez JA, McKenty PW, Sangster TC, Keck RL, Soures JM, Marshall FJ, Meyerhofer DD, Goncharov VN, Knauer JP, Radha PB, Regan SP, and Seka W

Abstract

Target areal density (rhoR) asymmetries in OMEGA direct-drive spherical implosions are studied. The rms variation / for low-mode-number structure is approximately proportional to the rms variation of on-target laser intensity / with an amplification factor of approximately 1/2(C(r)-1), where C(r) is the capsule convergence ratio. This result has critical implications for future work on the National Ignition Facility as well as OMEGA.

Published
2004
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34. Dependence of shell mix on feedthrough in direct drive inertial confinement fusion.

Author

Regan SP, Delettrez JA, Goncharov VN, Marshall FJ, Soures JM, Smalyuk VA, Radha PB, Yaakobi B, Epstein R, Glebov VY, Jaanimagi PA, Meyerhofer DD, Sangster TC, Seka W, Skupsky S, Stoeckl C, Haynes DA Jr, Frenje JA, Li CK, Petrasso RD, and Séguin FH

Abstract

The mixing of cold, high-density shell plasma with the low-density, hot spot plasma by the Rayleigh-Taylor instability in inertial confinement fusion is experimentally shown to correlate with the calculated perturbation feedthrough from the ablation surface to the inner shell surface. A fourfold decrease in the density of shell material in the mix region of direct drive implosions of gas filled spherical plastic shells having predicted convergence ratios approximately 15 was observed when laser imprint levels were reduced and the initial shell was thicker, corresponding to a reduction in the feedthrough rms level by a factor of 6. Shell mix is also shown to limit the spherical compression of the implosion.

Published
2004
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35. Multibeam effects on fast-electron generation from two-plasmon-decay instability.

Author

Stoeckl C, Bahr RE, Yaakobi B, Seka W, Regan SP, Craxton RS, Delettrez JA, Short RW, Myatt J, Maximov AV, and Baldis H

Abstract

Experiments with multiple laser beams have been carried out in both spherical and planar geometry to study two-plasmon-decay instability, the predominant source of suprathermal electrons in direct-drive inertial confinement fusion experiments. These electrons are observed using the hard x rays generated through electron-target interactions. The experiments show for the first time that the total overlapped intensity governs the scaling of the suprathermal-electron generation regardless of the number of overlapped beams, in contrast to conventional theories that are based on the single-beam approximation.

Published
2003
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36. Observation of saturation of energy transfer between copropagating beams in a flowing plasma.

Author

Kirkwood RK, Moody JD, Langdon AB, Cohen BI, Williams EA, Dorr MR, Hittinger JA, Berger R, Young PE, Suter LJ, Divol L, Glenzer SH, Landen OL, and Seka W

Abstract

Experiments demonstrate energy and power transfer between copropagating, same frequency, beams crossing at a small angle in a plasma with a Mach 1 flow. The process is interpreted as amplification of the low intensity probe beam by the stimulated scatter of the high intensity pump beam. The observed probe amplification increases slowly with pump intensity and decreases with probe intensity, indicative of saturation limiting the energy and power transfer due to ion-wave nonlinearities and localized pump depletion. The results are consistent with numerical modeling including ion-wave nonlinearities.

Published
2002
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37. Multibeam stimulated brillouin scattering from hot, solid-target plasmas.

Author

Seka W, Baldis HA, Fuchs J, Regan SP, Meyerhofer DD, Stoeckl C, Yaakobi B, Craxton RS, and Short RW

Abstract

We report on multibeam, laser-plasma interaction experiments in plasmas relevant to future direct-drive-ignition experiments. Six interaction beams are incident on preformed plasmas containing critical density. Stimulated Brillouin scattering (SBS) shows strong evidence of electromagnetic wave seeding of side- and backscattering. The data are also consistent with shared ion waves driven by the six symmetrically arranged interaction beams. Early SBS quenching is observed and attributed to the hydrodynamics of the plasma.

Published
2002
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38. Shell mix in the compressed core of spherical implosions.

Author

Regan SP, Delettrez JA, Marshall FJ, Soures JM, Smalyuk VA, Yaakobi B, Epstein R, Glebov VY, Jaanimagi PA, Meyerhofer DD, Radha PB, Sangster TC, Seka W, Skupsky S, Stoeckl C, Town RP, Haynes DA Jr, Golovkin IE, Hooper CF Jr, Frenje JA, Li CK, Petrasso RD, and Séguin FH

Abstract

The Rayleigh-Taylor instability in its highly nonlinear, turbulent stage causes atomic-scale mixing of the shell material with the fuel in the compressed core of inertial-confinement fusion targets. The density of shell material mixed into the outer core of direct-drive plastic-shell spherical-target implosions on the 60-beam, OMEGA laser system is estimated to be 3.4(+/-1.2) g/cm(3) from time-resolved x-ray spectroscopy, charged-particle spectroscopy, and core x-ray images. The estimated fuel density, 3.6(+/-1) g/cm(3), accounts for only approximately 50% of the neutron-burn-averaged electron density, n(e)=2.2(+/-0.4)x10(24) cm(-3).

Published
2002
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