Journal articles: 'OMEGA laser facility'

1

Ping, Yuan, and Federica Coppari. "Laser shock XAFS studies at OMEGA facility." High Pressure Research 36, no. 3 (July 2, 2016): 303–14. http://dx.doi.org/10.1080/08957959.2016.1196203.

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Niemann, C., G. Antonini, S. Compton, S. H. Glenzer, D. Hargrove, J. D. Moody, R. K. Kirkwood, et al. "Transmitted laser beam diagnostic at the Omega laser facility." Review of Scientific Instruments 75, no. 10 (October 2004): 4171–73. http://dx.doi.org/10.1063/1.1787602.

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Kelly, J. H., L. J. Waxer, V. Bagnoud, I. A. Begishev, J. Bromage, B. E. Kruschwitz, T. J. Kessler, et al. "OMEGA EP: High-energy petawatt capability for the OMEGA laser facility." Journal de Physique IV (Proceedings) 133 (June 2006): 75–80. http://dx.doi.org/10.1051/jp4:2006133015.

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4

Campbell, E. M., T. C. Sangster, V. N. Goncharov, J. D. Zuegel, S. F. B. Morse, C. Sorce, G. W. Collins, et al. "Direct-drive laser fusion: status, plans and future." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2189 (December 7, 2020): 20200011. http://dx.doi.org/10.1098/rsta.2020.0011.

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Laser-direct drive (LDD), along with laser indirect (X-ray) drive (LID) and magnetic drive with pulsed power, is one of the three viable inertial confinement fusion approaches to achieving fusion ignition and gain in the laboratory. The LDD programme is primarily being executed at both the Omega Laser Facility at the Laboratory for Laser Energetics and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. LDD research at Omega includes cryogenic implosions, fundamental physics including material properties, hydrodynamics and laser–plasma interaction physics. LDD research on the NIF is focused on energy coupling and laser–plasma interactions physics at ignition-scale plasmas. Limited implosions on the NIF in the ‘polar-drive’ configuration, where the irradiation geometry is configured for LID, are also a feature of LDD research. The ability to conduct research over a large range of energy, power and scale size using both Omega and the NIF is a major positive aspect of LDD research that reduces the risk in scaling from OMEGA to megajoule-class lasers. The paper will summarize the present status of LDD research and plans for the future with the goal of ultimately achieving a burning plasma in the laboratory. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

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BOEHLY, T. R., A. BABUSHKIN, D. K. BRADLEY, R. S. CRAXTON, J. A. DELETTREZ, R. EPSTEIN, T. J. KESSLER, et al. "Laser uniformity and hydrodynamic stability experiments at the OMEGA laser facility." Laser and Particle Beams 18, no. 1 (January 2000): 11–19. http://dx.doi.org/10.1017/s0263034600181029.

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Experiments to demonstrate the effects of various beam-smoothing techniques have been performed on the 60-beam, 30-kJ UV OMEGA laser system. These include direct measurements of the effect beam-smoothing techniques have on laser beam nonuniformity and on both planar and spherical targets. Demonstrated techniques include polarization smoothing and “dual-tripler” third-harmonic generation required for future broad bandwidth (∼1 THz) smoothing by spectral dispersion (SSD). The effects of improvements in single-beam uniformity are clearly seen in the target-physics experiments, which also show the effect of the laser pulse shape on the efficacy of SSD smoothing. Saturation of the Rayleigh-Taylor (RT) growth of the broad-bandwidth features, in agreement with the Haan model (Haan, 1989), produced by laser imprinting has also been observed.

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6

Froula, D. H., V. Rekow, C. Sorce, K. Piston, R. Knight, S. Alvarez, R. Griffith, et al. "3ω transmitted beam diagnostic at the Omega Laser Facility." Review of Scientific Instruments 77, no. 10 (October 2006): 10E507. http://dx.doi.org/10.1063/1.2221911.

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Rosen, P. A., J. M. Foster, R. J. R. Williams, B. H. Wilde, R. F. Coker, B. Blue, T. S. Perry, et al. "Laboratory-astrophysics jet experiments at the omega laser facility." Journal de Physique IV (Proceedings) 133 (June 2006): 1019–23. http://dx.doi.org/10.1051/jp4:2006133206.

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8

Soures, John M. "The Omega Upgrade laser facility for direct-drive experiements." Journal of Fusion Energy 10, no. 4 (December 1991): 295–98. http://dx.doi.org/10.1007/bf01052126.

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9

Soures, J. M., R. L. McCrory, T. R. Boehly, R. S. Craxton, S. D. Jacobs, J. H. Kelly, T. J. Kessler, et al. "OMEGA Upgrade laser for direct-drive target experiments." Laser and Particle Beams 11, no. 2 (June 1993): 317–21. http://dx.doi.org/10.1017/s0263034600004912.

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Validation of the direct-drive approach to inertial confinement fusion requires the development of a 351-nm wavelength, 30-kJ, 50-TW laser system with flexible pulse shaping and irradiation uniformity approaching 1%. An upgrade of the existing OMEGA direct-drive facility at Rochester is planned to meet these objectives. In this article, we review the design rationale and specifications of the OMEGA Upgrade laser with particular emphasis on techniques planned to achieve the required degree of beam smoothing, temporal pulse shape, and beam-to-beam power balance.

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10

Bennett, Guy R. "Advanced one-dimensional x-ray microscope for the Omega Laser Facility." Review of Scientific Instruments 70, no. 1 (January 1999): 608–12. http://dx.doi.org/10.1063/1.1149433.

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11

Sorce, C., J. Schein, F. Weber, K. Widmann, K. Campbell, E. Dewald, R. Turner, et al. "Soft x-ray power diagnostic improvements at the Omega Laser Facility." Review of Scientific Instruments 77, no. 10 (October 2006): 10E518. http://dx.doi.org/10.1063/1.2336462.

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12

Krasheninnikova, Natalia S., James A. Cobble, Thomas J. Murphy, Ian L. Tregillis, Paul A. Bradley, Peter Hakel, Scott C. Hsu, et al. "Designing symmetric polar direct drive implosions on the Omega laser facility." Physics of Plasmas 21, no. 4 (April 2014): 042703. http://dx.doi.org/10.1063/1.4870756.

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13

Celliers, P. M., D. K. Bradley, G. W. Collins, D. G. Hicks, T. R. Boehly, and W. J. Armstrong. "Line-imaging velocimeter for shock diagnostics at the OMEGA laser facility." Review of Scientific Instruments 75, no. 11 (November 2004): 4916–29. http://dx.doi.org/10.1063/1.1807008.

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14

McCrory, R. L., J. M. Soures, C. P. Verdon, F. J. Marshall, S. A. Letzring, T. J. Kessler, J. P. Knauer, et al. "High-density, direct-drive implosion experiments." Laser and Particle Beams 8, no. 1-2 (January 1990): 27–32. http://dx.doi.org/10.1017/s0263034600007801.

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A critical test of direct-drive laser-fusion has been conducted with the demonstration of DT compression to densities in the range of 100–200 times liquid density in experiments on the University of Rochester's OMEGA laser facility. The high-density cyrogenic experiments used 351-nm laser pulses with energies of 1500–1800 J and pulse widths in the range of 600–700 ps.

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15

Robey, H. F., P. Amendt, H. S. Park, R. P. J. Town, J. L. Milovich, T. Döppner, D. E. Hinkel, et al. "High performance capsule implosions on the OMEGA Laser facility with rugby hohlraums." Physics of Plasmas 17, no. 5 (May 2010): 056313. http://dx.doi.org/10.1063/1.3360926.

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16

Seely, J. F., C. I. Szabo, U. Feldman, L. T. Hudson, A. Henins, P. Audebert, and E. Brambrink. "Hard x-ray transmission crystal spectrometer at the OMEGA-EP laser facility." Review of Scientific Instruments 81, no. 10 (October 2010): 10E301. http://dx.doi.org/10.1063/1.3464232.

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17

Murphy, T. J., J. M. Wallace, N. D. Delamater, Cris W. Barnes, P. Gobby, A. A. Hauer, E. Lindman, et al. "Hohlraum Symmetry Experiments with Multiple Beam Cones on the Omega Laser Facility." Physical Review Letters 81, no. 1 (July 6, 1998): 108–11. http://dx.doi.org/10.1103/physrevlett.81.108.

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18

Szabo, C. I., J. Workman, K. Flippo, U. Feldman, J. F. Seely, L. T. Hudson, and A. Henins. "Scaling studies with the dual crystal spectrometer at the OMEGA-EP laser facility." Review of Scientific Instruments 81, no. 10 (October 2010): 10E320. http://dx.doi.org/10.1063/1.3494222.

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19

Avrorin, E. N., V. A. Lykov, V. E. Chernyakov, A. N. Shushlebin, K. A. Mustafin, V. D. Frolov, M. Yu Kozmanov, Ya Z. Kandiev, and A. A. Sofronoval. "Computational optimization of indirect-driven targets for ignition and the engineering test facility." Laser and Particle Beams 15, no. 1 (March 1997): 145–49. http://dx.doi.org/10.1017/s0263034600010843.

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The results of ID-ERA and 2D-TIGR, OMEGA codes calculations of compression and burn of indirect-driven targets for the thermonuclear ignition and Engineering Test Facility are presented. The possibility to obtain high-energy yield of G > 100 with driver energy of Ed = 5−10 MJ by using the heavy-ion one-beam accelerator as the main driver and powerful laser for fast ignition of thermonuclear detonation of cylindrical targets is pointed out.

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20

McCrory, R. L., J. M. Soures, J. P. Knauer, S. A. Letzring, F. J. Marshall, S. Skupsky, W. Seka, et al. "Short-wavelength-laser requirements for direct-drive ignition and gain." Laser and Particle Beams 11, no. 2 (June 1993): 299–306. http://dx.doi.org/10.1017/s0263034600004894.

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Inertial confinement fusion (ICF) requires high compression of fusion fuel to densities approaching 1000 times liquid density of deuterium-tritium (D–T) at central temperatures in excess of 5 keV. The goal of ICF is to achieve high gain (of the order of 100 or greater) in the laboratory. To meet this objective with minimum driver energy, a number of central issues must be addressed. Research in ICF with laser drivers has shown the importance of using short wavelength (λ < 0.5 µm). To achieve conditions for high gain at driver energies of a few megajoules or less, high intensities (>1014W/cm2) are required. The directdrive approach to ICF is more energy efficient than indirect drive if the stringent drive symmetry and hydrodynamic stability requirements can be met by a suitable laser irradiation scheme and target design. Experiments carried out at 351 nm on the 2-kJ, 24-beam OMEGA laser system at the Laboratory for Laser Energetics (LLE) at the University of Rochester, and future experiments to be performed on a 30-kJ upgrade of this laser, can resolve the remaining physics issues for direct drive: (1) energy coupling and transport scaling; (2) irradiation-uniformity requirements for high gain; (3) hydrodynamic stability constraints; and (4) hot-spot and main-fuel-layer physics. We review progress made on achieving uniform drive conditions with the OMEGA system and present results for direct-drive cryogenic-fuel-capsule and CD-shell, “surrogate” cryogenic-capsule implosion experiments that illustrate the constraints imposed by hydrodynamic instabilities and drive uniformity on the design of high-performance direct-drive targets. Target designs have been identified that will explore the ignition-scaling regime using the OMEGA Upgrade. Experiments on the OMEGA Upgrade will signal whether or not there is a high probability of achieving modest to high gain using direct drive on an upgrade of the NOVA facility.

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21

Coppari, F., R. F. Smith, D. B. Thorn, J. R. Rygg, D. A. Liedahl, R. G. Kraus, A. Lazicki, M. Millot, and J. H. Eggert. "Optimized x-ray sources for x-ray diffraction measurements at the Omega Laser Facility." Review of Scientific Instruments 90, no. 12 (December 1, 2019): 125113. http://dx.doi.org/10.1063/1.5111878.

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22

KILKENNY, J. D., T. P. BERNAT, B. A. HAMMEL, R. L. KAUFFMAN, O. L. LANDEN, J. D. LINDL, B. J. MacGOWAN, J. A. PAISNER, and H. T. POWELL. "Lawrence Livermore National Laboratory's activities to achieve ignition by X-ray drive on the National Ignition Facility." Laser and Particle Beams 17, no. 2 (April 1999): 159–71. http://dx.doi.org/10.1017/s0263034699172021.

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The National Ignition Facility (NIF) is a MJ-class glass laser-based facility funded by the Department of Energy which has achieved thermonuclear ignition and moderate gain as one of its main objectives. In the summer of 1998, the project was about 40% complete, and design and construction was on schedule and on cost. The NIF will start firing onto targets in 2001, and will achieve full energy in 2004. The Lawrence Livermore National Laboratory (LLNL) together with the Los Alamos National Laboratory (LANL) have the main responsibility for achieving X-ray driven ignition on the NIF. In the 1990s, a comprehensive series of experiments on Nova at LLNL, followed by recent experiments on the Omega laser at the University of Rochester, demonstrated confidence in understanding the physics of X-ray drive implosions. The same physics at equivalent scales is used in calculations to predict target performance on the NIF, giving credence to calculations of ignition on the NIF. An integrated program of work in preparing the NIF for X-ray driven ignition in about 2007, and the key issues being addressed on the current Inertial Confinement Fusion (ICF) facilities [(Nova, Omega, Z at Sandia National Laboratory (SNL) and NIKE at the Naval Research Laboratory (NRL)], are described.

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23

Masson-Laborde, P. E., M. C. Monteil, V. Tassin, F. Philippe, P. Gauthier, A. Casner, S. Depierreux, et al. "Laser plasma interaction on rugby hohlraum on the Omega Laser Facility: Comparisons between cylinder, rugby, and elliptical hohlraums." Physics of Plasmas 23, no. 2 (February 2016): 022703. http://dx.doi.org/10.1063/1.4941706.

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24

TUBBS, D. L., C. W. BARNES, J. B. BECK, N. M. HOFFMAN, J. A. OERTEL, R. G. WATT, T. BOEHLY, D. BRADLEY, and J. KNAUER. "Direct-drive cylindrical implosion experiments: Simulations and data." Laser and Particle Beams 17, no. 3 (July 1999): 437–49. http://dx.doi.org/10.1017/s0263034699173117.

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We have studied a suite of cylindrical, polystyrene targets, both unperturbed and with mode-28, 1.5 μm initial-amplitude sinusoidal perturbations imposed azimuthally along the target length. All targets are driven by direct laser illumination at 3ω using the University of Rochester OMEGA laser facility. Our numerical simulation and experimental data demonstrate the proof of principle for direct-drive studies of complex hydrodynamic phenomena in convergent geometry. We obtain high-quality, time-dependent data, that demonstrate good implosion symmetry and against which numerical simulations show promising agreement within currently assessed error bars. Our results identify operational space for continuing experiments.

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25

Fiksel, G., A. Agliata, D. Barnak, G. Brent, P. Y. Chang, L. Folnsbee, G. Gates, et al. "Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility." Review of Scientific Instruments 86, no. 1 (January 2015): 016105. http://dx.doi.org/10.1063/1.4905625.

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26

Okishev, A. V., and W. Seka. "Diode-pumped Nd:YLF master oscillator for the 30-kJ (UV), 60-beam OMEGA laser facility." IEEE Journal of Selected Topics in Quantum Electronics 3, no. 1 (1997): 59–63. http://dx.doi.org/10.1109/2944.585815.

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27

Kemp, G. E., A. Link, Y. Ping, S. Ayers, and P. K. Patel. "Commissioning of a frequency-resolved optical gating system at the OMEGA EP laser facility: SpecFROG." Review of Scientific Instruments 86, no. 9 (September 2015): 093501. http://dx.doi.org/10.1063/1.4929868.

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28

Michel, D. T., D. H. Edgell, D. H. Froula, R. K. Follett, V. N. Goncharov, J. F. Myatt, S. Skupsky, and B. Yaakobi. "Hydrodynamic simulations of long-scale-length two-plasmon–decay experiments at the Omega Laser Facility." Physics of Plasmas 20, no. 3 (March 2013): 032704. http://dx.doi.org/10.1063/1.4794285.

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29

Gatu Johnson, M., J. Katz, C. Forrest, J. A. Frenje, V. Yu Glebov, C. K. Li, R. Paguio, et al. "Measurement of apparent ion temperature using the magnetic recoil spectrometer at the OMEGA laser facility." Review of Scientific Instruments 89, no. 10 (October 2018): 10I129. http://dx.doi.org/10.1063/1.5035287.

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30

Smalyuk, V. A., J. F. Hansen, O. A. Hurricane, G. Langstaff, D. Martinez, H. S. Park, K. Raman, et al. "Experimental observations of turbulent mixing due to Kelvin–Helmholtz instability on the OMEGA Laser Facility." Physics of Plasmas 19, no. 9 (September 2012): 092702. http://dx.doi.org/10.1063/1.4752015.

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31

Okishev, A. V., D. Westerfeld, L. Shterengas, and G. Belenky. "A stable mid-IR, GaSb-based diode laser source for the cryogenic target layering at the Omega Laser Facility." Optics Express 17, no. 18 (August 20, 2009): 15760. http://dx.doi.org/10.1364/oe.17.015760.

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32

Do, A., F. Coppari, Y. Ping, A. Krygier, G. E. Kemp, M. B. Schneider, and J. M. McNaney. "Foil backlighter development at the OMEGA laser facility for extended x-ray absorption fine structure experiments." Review of Scientific Instruments 91, no. 8 (August 1, 2020): 086101. http://dx.doi.org/10.1063/5.0015313.

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33

Tikhonchuk, V. T. "Progress and opportunities for inertial fusion energy in Europe." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2184 (October 12, 2020): 20200013. http://dx.doi.org/10.1098/rsta.2020.0013.

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In this paper, I consider the motivations, recent results and perspectives for the inertial confinement fusion (ICF) studies in Europe. The European approach is based on the direct drive scheme with a preference for the central ignition boosted by a strong shock. Compared to other schemes, shock ignition offers a higher gain needed for the design of a future commercial reactor and relatively simple and technological targets, but implies a more complicated physics of laser–target interaction, energy transport and ignition. European scientists are studying physics issues of shock ignition schemes related to the target design, laser plasma interaction and implosion by the code developments and conducting experiments in collaboration with US and Japanese physicists, providing access to their installations Omega and Gekko XII. The ICF research in Europe can be further developed only if European scientists acquire their own academic laser research facility specifically dedicated to controlled fusion energy and going beyond ignition to the physical, technical, technological and operational problems related to the future fusion power plant. Recent results show significant progress in our understanding and simulation capabilities of the laser plasma interaction and implosion physics and in our understanding of material behaviour under strong mechanical, thermal and radiation loads. In addition, growing awareness of environmental issues has attracted more public attention to this problem and commissioning at ELI Beamlines the first high-energy laser facility with a high repetition rate opens the opportunity for qualitatively innovative experiments. These achievements are building elements for a new international project for inertial fusion energy in Europe. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.

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34

KYRALA, GEORGE A., NORMAN DELAMATER, DOUGLAS WILSON, JOYCE GUZIK, DON HAYNES, MARK GUNDERSON, KENNETH KLARE, ROBERT W. WATT, WILLIAM M. WOOD, and WILLIAM VARNUM. "Direct drive double shell target implosion hydrodynamics on OMEGA." Laser and Particle Beams 23, no. 2 (June 2005): 187–92. http://dx.doi.org/10.1017/s0263034605050330.

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Imploding indirect-drive double shell targets may provide an alternative, non-cryogenic path to ignition at the National Ignition Facility (NIF). Experiments are being pursued at OMEGA to understand the hydrodynamics of these implosions and the possibility of scaling it to the NIF design. We have used 40 beams from the OMEGA laser to directly drive the capsules, and we have used the remaining 20 beams to backlight the imploding shells from two different directions at multiple times. We will review the recent experiments to measure the hydrodynamics of the targets using two-view X-ray radiography of the capsules. We will present data on measured yields from the targets. We will present a measured time history of the hydrodynamics of the implosion. Experiments were pursued using direct drive in which the M-band effect (experienced in the indirect drive experiments) could be eliminated or controlled. It was learned in the direct drive experiments that the best performing capsules were those that had a thin outer layer of gold. This effectively causes M-band pre-heat effects giving implosion hydrodynamics and performance closer to the indirect drive case. We will review the methods used to radiograph the targets and the techniques used to extract useful information to compare with calculations. The effect of imperfections in the target construction will be shown to be minimal during the initial stage of implosion. The yields from the targets were observed to be uniformly low compared to indirect-drive.

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35

Cetilia, Mark. "Pulse Shape 22: Audiovisual Performance and Data Transmutation." Leonardo 49, no. 4 (August 2016): 317–23. http://dx.doi.org/10.1162/leon_a_01284.

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Pulse Shape 22 is an improvisational audiovisual performance featuring shortwave radio transmissions as the sole source material for real-time audio processing alongside video of the sun projected through cast-glass lenses designed specifically for this piece. The structure of the piece is derived from metrics on energy accumulation over a period of 2.2 nanoseconds resulting from the targeting of 60 laser beams on a single tetrahedral hohlraum in weapons testing experiments as carried out by the Los Alamos Inertial Confinement Fusion unit, at the Omega Laser Facility at the University of Rochester. Pulse Shape 22 is an exploration of architectural space through the use of site- and time-specific information found in regions of the electromagnetic spectrum outside the reaches of the human sensory apparatus. It is an attempt to alter the audience’s perceptions of their surroundings and create a moment of rupture from hidden worlds found in our local environment.

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Frenje, J. A., C. K. Li, F. H. Séguin, D. G. Hicks, S. Kurebayashi, R. D. Petrasso, S. Roberts, et al. "Absolute measurements of neutron yields from DD and DT implosions at the OMEGA laser facility using CR-39 track detectors." Review of Scientific Instruments 73, no. 7 (July 2002): 2597–605. http://dx.doi.org/10.1063/1.1487889.

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37

Seifter, A., G. A. Kyrala, S. R. Goldman, N. M. Hoffman, J. L. Kline, and S. H. Batha. "Demonstration of symcaps to measure implosion symmetry in the foot of the NIF scale 0.7 hohlraums." Laser and Particle Beams 27, no. 1 (January 23, 2009): 123–27. http://dx.doi.org/10.1017/s0263034609000184.

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AbstractImplosions using inertial confinement fusion must be highly symmetric to achieve ignition on the National Ignition Facility. This requires precise control of the drive symmetry from the radiation incident on the ignition capsule. For indirect drive implosions, low mode residual perturbations in the drive are generated by the laser-heated hohlraum geometry. To diagnose the drive symmetry, previous experiments used simulated capsules by which the self-emission X-rays from gas in the center of the capsule during the implosion are used to infer the shape of the drive. However, those experiments used hohlraum radiation temperatures higher than 200 eV (Hauer et al., 1995; Murphy et al., 1998a, 1998b) with small NOVA scale hohlraums under which conditions the symcaps produced large X-ray signals. At the foot of the NIF ignition pulse, where controlling the symmetry has been shown to be crucial for obtaining a symmetric implosion (Clark et al., 2008), the radiation drive is much smaller, reducing the X-ray emission from the imploded capsule. For the first time, the feasibility of using symcaps to diagnose the radiation drive for low radiation temperatures, <120 eV and large 0.7 linear scales NIF Rev3.1 (Haan et al., 2008) vacuum hohlraums is demonstrated. Here we used experiments at the Omega laser facility to demonstrate and develop the symcap technique for tuning the symmetry of the NIF ignition capsule in the foot of the drive pulse.

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38

Chatain, D., J. P. Périn, P. Bonnay, E. Bouleau, M. Chichoux, D. Communal, J. Manzagol, et al. "Cryogenic systems for inertial fusion energy." Laser and Particle Beams 26, no. 4 (September 18, 2008): 517–23. http://dx.doi.org/10.1017/s0263034608000554.

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AbstractThe Low Temperatures Laboratory of CEA/Grenoble (France) is involved in the development of cryogenic systems for inertial fusion since a ten of years. A conceptual design for the cryogenic infrastructure of the Laser MegaJoule (LMJ) facility has been proposed. Several prototypes have been designed, built and tested like for example the 1500 bars cryo compressor for the targets filling, the target positioner and the thermal shroud remover.The HIPER project will necessitate the development of such equipments. The main difference is that this time, the cryogenic targets are direct drive targets. The first phase of HIPER experiments is a single shot period. Based on the experience gained the last years, not only by our laboratory but also by Omega and G.A teams, we could design the new HIPER equipments for this phase.Some experimental results obtained with the prototypes of the LMJ cryogenic system are given and a first conceptual design for the HIPER single shot cryogenic system is shown.

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39

Bradley, D. K., S. T. Prisbrey, R. H. Page, D. G. Braun, M. J. Edwards, R. Hibbard, K. A. Moreno, M. P. Mauldin, and A. Nikroo. "Measurements of preheat and shock melting in Be ablators during the first few nanoseconds of a National Ignition Facility ignition drive using the Omega laser." Physics of Plasmas 16, no. 4 (April 2009): 042703. http://dx.doi.org/10.1063/1.3104702.

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40

Gatu Johnson, M., B. Aguirre, J. Armstrong, J. A. Fooks, C. Forrest, J. A. Frenje, V. Yu Glebov, et al. "Using millimeter-sized carbon–deuterium foils for high-precision deuterium–tritium neutron spectrum measurements in direct-drive inertial confinement fusion at the OMEGA laser facility." Review of Scientific Instruments 92, no. 2 (February 1, 2021): 023503. http://dx.doi.org/10.1063/5.0040549.

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41

Gigosos, Marco A., Roberto C. Mancini, Juan M. Martín-González, and Ricardo Florido. "Stark-Broadening of Ar K-Shell Lines: A Comparison between Molecular Dynamics Simulations and MERL Results." Atoms 9, no. 1 (January 25, 2021): 9. http://dx.doi.org/10.3390/atoms9010009.

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Analysis of Stark-broadened spectral line profiles is a powerful, non-intrusive diagnostic technique to extract the electron density of high-energy-density plasmas. The increasing number of applications and availability of spectroscopic measurements have stimulated new research on line broadening theory calculations and computer simulations, and their comparison. Here, we discuss a comparative study of Stark-broadened line shapes calculated with computer simulations using non-interacting and interacting particles, and with the multi-electron radiator line shape MERL code. In particular, we focus on Ar K-shell X-ray line transitions in He- and H-like ions, i.e., Heα, Heβ and Heγ in He-like Ar and Lyα, Lyβ and Lyγ in H-like Ar. These lines have been extensively used for X-ray spectroscopy of Ar-doped implosion cores in indirect- and direct-drive inertial confinement fusion (ICF) experiments. The calculations were done for electron densities ranging from 1023 to 3×1024 cm−3 and a representative electron temperature of 1 keV. Comparisons of electron broadening only and complete line profiles including electron and ion broadening effects, as well as Doppler, are presented. Overall, MERL line shapes are narrower than those from independent and interacting particles computer simulations performed at the same conditions. Differences come from the distinctive treatments of electron broadening and are more pronounced in α line transitions. We also discuss the recombination broadening mechanism that naturally emerges from molecular dynamics simulations and its influence on the line shapes. Furthermore, we assess the impact of employing either molecular dynamics or MERL line profiles on the diagnosis of core conditions in implosion experiments performed on the OMEGA laser facility.

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May, M. J., P. Beiersdorfer, G. V. Brown, K. B. Fournier, M. Gu, S. B. Hansen, M. Schneider, et al. "Measuring the ionization balance of gold in a low-density plasma ofimportance to inertial confinement fusion." Canadian Journal of Physics 86, no. 1 (January 1, 2008): 251–58. http://dx.doi.org/10.1139/p07-150.

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Charge state distributions (CSDs) have been determined in low-density (≈1012 cm–3) gold plasmas having either a monoenergetic beam (EBeam = 2.66, 3.53, 4.54, 5.35, 5.85, and 6.35 keV) or experimentally simulated thermal electron distributions (Te = 2.0, 2.5, and 3.0 keV). These plasmas were created in the Livermore electron beam ion traps, EBIT-I and EBIT-II. Line emission and radiative recombination features of K to Kr-like gold ions were recorded in the X-ray region with a crystal spectrometer and a photometrically calibrated microcalorimeter. The CSDs in the experimentally simulated thermal plasmas were inferred by fitting the observed 4f → 3d and 5f → 3d lines with synthetic spectra from the Hebrew University Lawrence Livermore Atomic Code (HULLAC). Additionally, the CSDs in the beam plasmas were inferred both from fitting the line emission and fitting the radiative recombination emission to calculations from the General Relativistic Atomic Structure Program. Despite the relatively simple atomic physics in the low-density plasma, differences existed between the experimental CSDs and the simulations from several available codes (for example, RIGEL). Our experimental CSD relied upon accurate electron impact cross sections provided by HULLAC. To determine their reliability, we have experimentally determined the cross sections for several of the n = 3 → 4 and n = 3 → 5 excitations in Ni to Ga-like Au and compared them to distorted wave calculations. Cross-section calculations by flexible atomic code (FAC) and HULLAC were found to be very consistent. Recent Au spectra recorded during experiments at the OMEGA laser facility are presented and compared with those recorded from EBIT-I and EBIT-II. This comparison shows that spectra from the two sources are surprisingly similar despite a 10 order of magnitude difference in their respective plasma densities. PACS Nos.: 52.50.Fs, 52.25.Jm, 34.80.Kw, 34.80.Lx

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"Lawmakers act to rescue Omega laser facility." Physics Today, June 1, 2018. http://dx.doi.org/10.1063/pt.6.2.20180601a.

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Shaw, J. L., M. A. Romo-Gonzalez, N. Lemos, P. M. King, G. Bruhaug, K. G. Miller, C. Dorrer, et al. "Microcoulomb (0.7 ± $$\frac{0.4}{0.2}$$ μC) laser plasma accelerator on OMEGA EP." Scientific Reports 11, no. 1 (April 5, 2021). http://dx.doi.org/10.1038/s41598-021-86523-5.

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AbstractLaser-plasma accelerators (LPAs) driven by picosecond-scale, kilojoule-class lasers can generate particle beams and x-ray sources that could be utilized in experiments driven by multi-kilojoule, high-energy-density science (HEDS) drivers such as the OMEGA laser at the Laboratory for Laser Energetics (LLE) or the National Ignition Facility at Lawrence Livermore National Laboratory. This paper reports on the development of the first LPA driven by a short-pulse, kilojoule-class laser (OMEGA EP) connected to a multi-kilojoule HEDS driver (OMEGA). In experiments, electron beams were produced with electron energies greater than 200 MeV, divergences as low as 32 mrad, charge greater than 700 nC, and conversion efficiencies from laser energy to electron energy up to 11%. The electron beam charge scales with both the normalized vector potential and plasma density. These electron beams show promise as a method to generate MeV-class radiography sources and improved-flux broadband x-ray sources at HEDS drivers.

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Rigby, A., J. Katz, A. F. A. Bott, T. G. White, P. Tzeferacos, D. Q. Lamb, D. H. Froula, and G. Gregori. "Implementation of a Faraday rotation diagnostic at the OMEGA laser facility." High Power Laser Science and Engineering 6 (2018). http://dx.doi.org/10.1017/hpl.2018.42.

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Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for ${\geqslant}$kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This diagnostic has been implemented using the Thomson scattering probe beam and the resultant path-integrated magnetic field has been compared with that of proton radiography. Accurate measurement of magnetic fields is essential for satisfying the scientific goals of many current laser–plasma experiments.

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Capelli, D., C. A. Charsley-Groffman, R. B. Randolph, D. W. Schmidt, T. Cardenas, F. Fierro, G. Rivera, et al. "Developing targets for radiation transport experiments at the Omega laser facility." High Power Laser Science and Engineering 5 (2017). http://dx.doi.org/10.1017/hpl.2017.14.

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Targets have been developed to measure supersonic radiation transport in aerogel foams using absorption spectroscopy. The target consists of an aerogel foam uniformly doped with either titanium or scandium inserted into an undoped aerogel foam package. This creates a localized doped foam region to provide spatial resolution for the measurement. Development and characterization of the foams is a key challenge in addition to machining and assembling the two foams so they mate without gaps. The foam package is inserted into a beryllium sleeve and mounted on a gold hohlraum. The target is mounted to a holder created using additive manufacturing and mounted on a stalk. The manufacturing of the components, along with assembly and metrology of the target are described here.

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Amendt, Peter A., Harry F. Robey, H. S. Park, R. E. Tipton, R. E. Turner, J. L. Milovich, M. Bono, et al. "Hohlraum-Driven Ignitionlike Double-Shell Implosions on the Omega Laser Facility." Physical Review Letters 94, no. 6 (February 18, 2005). http://dx.doi.org/10.1103/physrevlett.94.065004.

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Zhao, Dongfeng, Li Wan, Zunqi Lin, Pin Shao, and Jianqiang Zhu. "SG-II-Up prototype final optics assembly: optical damage and clean-gas control." High Power Laser Science and Engineering 3 (2015). http://dx.doi.org/10.1017/hpl.2015.1.

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The Shenguang-II Upgrade (SG-II Up) facility is an under-construction high-power laser driver with eight beams, 24 kJ energy, 3 ns pulse duration and ultraviolet laser output, in the Shanghai Institute of Optics and Fine Mechanics, China. The prototype design and experimental research of the prototype final optics assembly (FOA), which is one of the most important parts of the SG-II Up facility, have been completed on the ninth beam of the SG-II facility. Thirty-three shots were fired using 1- ${\it\omega}$ energy from 1000 to 4500 J and 3- ${\it\omega}$ energy from 500 to 2403 J with a 3 ns square pulse. During the experiments, emphasis was given to the process of optical damage and to the effects of clean-gas control. A numerical model of the FOA generated by the Integrated Computer Engineering and Manufacturing code for Computational Fluid Dynamics (ICEMCFD) demonstrated that a flux within $1{-}5~\text{l s}^{-1}$ and a 180 s period is effectual to avoid contaminant sputtering to the optics. The presence of surface ‘mooning’ damage and surface spots located outside the clear aperture are induced by contaminants such as wire, silica gel and millimeter order fiber and metal.

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Wilson, Brandon M., and Aaron Koskelo. "Assessment of Model Confidence of a Laser Source Model in xRAGE Using Omega Direct-Drive Implosion Experiments." Journal of Verification, Validation and Uncertainty Quantification 3, no. 4 (December 1, 2018). http://dx.doi.org/10.1115/1.4043370.

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Los Alamos National Laboratory is interested in developing high-energy-density physics validation capabilities for its multiphysics code xRAGE. xRAGE was recently updated with the laser package Mazinisin to improve predictability. We assess the current implementation and coupling of the laser package via validation of laser-driven, direct-drive spherical capsule experiments from the Omega laser facility. The ASME V&V 20-2009 standard is used to determine the model confidence of xRAGE, and considerations for high-energy-density physics are identified. With current modeling capabilities in xRAGE, the model confidence is overwhelmed by significant systematic errors from the experiment or model. Validation evidence suggests cross-beam energy transfer as a dominant source of the systematic error.

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Amendt, Peter, R. E. Turner, and O. L. Landen. "Hohlraum-Driven High-Convergence Implosion Experiments with Multiple Beam Cones on the Omega Laser Facility." Physical Review Letters 89, no. 16 (September 26, 2002). http://dx.doi.org/10.1103/physrevlett.89.165001.

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Journal articles on the topic 'OMEGA laser facility'

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