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Mannion OM, Woo KM, Crilly AJ, Forrest CJ, Frenje JA, Johnson MG, Glebov VY, Knauer JP, Mohamed ZL, Romanofsky MH, Stoeckl C, Theobald W, Regan SP. Reconstructing 3D asymmetries in laser-direct-drive implosions on OMEGA. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033529. [PMID: 33819982 DOI: 10.1063/5.0043514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Three-dimensional reconstruction algorithms have been developed, which determine the hot-spot velocity, hot-spot apparent ion temperature distribution, and fuel areal-density distribution present in laser-direct-drive inertial confinement fusion implosions on the OMEGA laser. These reconstructions rely on multiple independent measurements of the neutron energy spectrum emitted from the fusing plasma. Measurements of the neutron energy spectrum on OMEGA are made using a suite of quasi-orthogonal neutron time-of-flight detectors and a magnetic recoil spectrometer. These spectrometers are positioned strategically around the OMEGA target chamber to provide unique 3D measurements of the conditions of the fusing hot spot and compressed fuel near peak compression. The uncertainties involved in these 3D reconstructions are discussed and are used to identify a new nTOF diagnostic line of sight, which when built will reduce the uncertainty in the hot-spot apparent ion temperature distribution from 700 to <400 eV.
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Koester P, Baffigi F, Cristoforetti G, Labate L, Gizzi LA, Baton S, Koenig M, Colaïtis A, Batani D, Casner A, Raffestin D, Tentori A, Trela J, Rousseaux C, Boutoux G, Brygoo S, Jacquet L, Reverdin C, Le Bel E, Le-Deroff L, Theobald W, Shigemori K. Bremsstrahlung cannon design for shock ignition relevant regime. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:013501. [PMID: 33514221 DOI: 10.1063/5.0022030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
We report on the optimization of a BremsStrahlung Cannon (BSC) design for the investigation of laser-driven fast electron populations in a shock ignition relevant experimental campaign at the Laser Megajoule-PETawatt Aquitaine Laser facility. In this regime with laser intensities of 1015 W/cm2-1016 W/cm2, fast electrons with energies ≤100 keV are expected to be generated through Stimulated Raman Scattering (SRS) and Two Plasmon Decay (TPD) instabilities. The main purpose of the BSC in our experiment is to identify the contribution to x-ray emission from bremsstrahlung of fast electrons originating from SRS and TPD, with expected temperatures of 40 keV and 95 keV, respectively. Data analysis and reconstruction of the distributions of x-ray photons incident on the BSC are described.
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Ceurvorst L, Betti R, Casner A, Gopalaswamy V, Bose A, Hu SX, Campbell EM, Regan SP, McCoy CA, Karasik M, Peebles J, Tabak M, Theobald W. Hybrid target design for imprint mitigation in direct-drive inertial confinement fusion. Phys Rev E 2020; 101:063207. [PMID: 32688486 DOI: 10.1103/physreve.101.063207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 05/13/2020] [Indexed: 11/07/2022]
Abstract
A target design for mitigating the Rayleigh-Taylor instability is proposed for use in high energy density and direct-drive inertial confinement fusion experiments. In this scheme, a thin gold membrane is offset from the main target by several-hundred microns. A strong picket on the drive beams is incident upon this membrane to produce x rays which generate the initial shock through the target. The main drive follows shortly thereafter, passing through the ablated shell and directly driving the main target. The efficacy of this scheme is demonstrated through experiments performed at the OMEGA EP facility, showing a reduction of the Rayleigh-Taylor instability growth which scales exponentially with frequency, suppressing development by at least a factor of 5 for all wavelengths below 100 μm. This results in a delay in the time of target perforation by ∼40%.
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Theobald W, Sorce C, Donaldson WR, Epstein R, Keck RL, Kellogg C, Kessler TJ, Kwiatkowski J, Marshall FJ, Sampat S, Seka W, Shah RC, Shvydky A, Stoeckl C, Waxer LJ, Regan SP. Inferred UV fluence focal-spot profiles from soft x-ray pinhole-camera measurements on OMEGA. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:023505. [PMID: 32113463 DOI: 10.1063/1.5120708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 01/14/2020] [Indexed: 06/10/2023]
Abstract
A method was developed with laser-irradiated Au planar foils to characterize the focal spot of UV laser beams on a target at full energy from soft x-ray emission. A pinhole camera with a back-thinned charge-coupled device detector and filtration with thin Be and Al foil filters provides images of the x-ray emission at photon energies <2 keV. This method requires a careful measurement of the relationship between the applied UV fluence and the x-ray signal, which can be described by a power-law dependence. The measured exponent γ ∼ 2 provides a dynamic range of ∼25 for the inferred UV fluence. UV fluence profiles of selected beams were measured for 100-ps and 1-ns laser pulses and were compared to directly measured profiles from an UV equivalent-target-plane diagnostic. The inferred spot size and super-Gaussian order from the x-ray technique agree within several percent with the values measured with the direct UV measurements.
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Hu SX, Epstein R, Theobald W, Xu H, Huang H, Goncharov VN, Regan SP, McKenty PW, Betti R, Campbell EM, Montgomery DS. Direct-drive double-shell implosion: A platform for burning-plasma physics studies. Phys Rev E 2020; 100:063204. [PMID: 31962495 DOI: 10.1103/physreve.100.063204] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Indexed: 11/07/2022]
Abstract
Double-shell ignition designs have been studied with the indirect-drive inertial confinement fusion (ICF) scheme in both simulations and experiments in which the inner-shell kinetic energy was limited to ∼10-15 kJ, even driven by megajoule-class lasers such as the National Ignition Facility. Since direct-drive ICF can couple more energy to the imploding shells, we have performed a detailed study on direct-drive double-shell (D^{3}S) implosions with state-of-the-art physics models implemented in radiation-hydrodynamic codes (lilac and draco), including nonlocal thermal transport, cross-beam energy transfer (CBET), and first-principles-based material properties. To mitigate classical unstable interfaces, we have proposed the use of a tungsten-beryllium-mixed inner shell with gradient-density layers that can be made by magnetron sputtering. In our D^{3}S designs, a 70-μm-thick beryllium outer shell is driven symmetrically by a high-adiabat (α≥10), 1.9-MJ laser pulse to a peak velocity of ∼240 km/s. Upon spherical impact, the outer shell transfers ∼30-40 kJ of kinetic energy to the inner shell filled with deuterium-tritium gas or liquid, giving neutron-yield energies of ∼6 MJ in one-dimensional simulations. Two-dimensional high-mode draco simulations indicated that such high-adiabat D^{3}S implosions are not susceptible to laser imprint, but the long-wavelength perturbations from the laser port configuration along with CBET can be detrimental to the target performance. Nevertheless, neutron yields of ∼0.3-1.0-MJ energies can still be obtained from our high-mode draco simulations. The robust α-particle bootstrap is readily reached, which could provide a viable platform for burning-plasma physics studies. Once CBET mitigation and/or more laser energy becomes available, we anticipate that break-even or moderate energy gain might be feasible with the proposed D^{3}S scheme.
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Habara H, Iwawaki T, Gong T, Wei MS, Ivancic ST, Theobald W, Krauland CM, Zhang S, Fiksel G, Tanaka KA. A ten-inch manipulator (TIM) based fast-electron spectrometer with multiple viewing angles (OU-ESM). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:063501. [PMID: 31255022 DOI: 10.1063/1.5088529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
The measurement of angularly resolved energy distributions of mega-electron-volt electrons is important for gaining a better understanding of the interaction of ultra-intense laser pulses with plasma, especially for fast-ignition laser-fusion research. It is also crucial when evaluating the production of suprathermal (several 10-keV) electrons through laser-plasma instabilities in conventional hot-spot-ignition and shock-ignition research. For these purposes, we developed a 10-in. manipulator-based multichannel electron spectrometer-the Osaka University electron spectrometer (OU-ESM)-that combines angular resolution with high-energy resolution. The OU-ESM consists of five small electron spectrometers set at every 5°, with an energy range from ∼40 keV to ∼40 MeV. A low-magnetic-field option provides a higher spectral resolution for an energy range of up to ∼5 MeV. We successfully obtained angularly resolved electron spectra for various experiments on the OMEGA and OMEGA EP laser systems.
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Peebles JL, Hu SX, Theobald W, Goncharov VN, Whiting N, Celliers PM, Ali SJ, Duchateau G, Campbell EM, Boehly TR, Regan SP. Direct-drive measurements of laser-imprint-induced shock velocity nonuniformities. Phys Rev E 2019; 99:063208. [PMID: 31330608 DOI: 10.1103/physreve.99.063208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Indexed: 06/10/2023]
Abstract
Perturbations in the velocity profile of a laser-ablation-driven shock wave seeded by speckle in the spatial beam intensity (i.e., laser imprint) have been measured. Direct measurements of these velocity perturbations were recorded using a two-dimensional high-resolution velocimeter probing plastic material shocked by a 100-ps picket laser pulse from the OMEGA laser system. The measured results for experiments with one, two, and five overlapping beams incident on the target clearly demonstrate a reduction in long-wavelength (>25-μm) perturbations with an increasing number of overlapping laser beams, consistent with theoretical expectations. These experimental measurements are crucial to validate radiation-hydrodynamics simulations of laser imprint for laser direct drive inertial confinement fusion research since they highlight the significant (factor of 3) underestimation of the level of seeded perturbation when the microphysics processes for initial plasma formation, such as multiphoton ionization are neglected.
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Gopalaswamy V, Betti R, Knauer JP, Luciani N, Patel D, Woo KM, Bose A, Igumenshchev IV, Campbell EM, Anderson KS, Bauer KA, Bonino MJ, Cao D, Christopherson AR, Collins GW, Collins TJB, Davies JR, Delettrez JA, Edgell DH, Epstein R, Forrest CJ, Froula DH, Glebov VY, Goncharov VN, Harding DR, Hu SX, Jacobs-Perkins DW, Janezic RT, Kelly JH, Mannion OM, Maximov A, Marshall FJ, Michel DT, Miller S, Morse SFB, Palastro J, Peebles J, Radha PB, Regan SP, Sampat S, Sangster TC, Sefkow AB, Seka W, Shah RC, Shmyada WT, Shvydky A, Stoeckl C, Solodov AA, Theobald W, Zuegel JD, Johnson MG, Petrasso RD, Li CK, Frenje JA. Tripled yield in direct-drive laser fusion through statistical modelling. Nature 2019; 565:581-586. [PMID: 30700868 DOI: 10.1038/s41586-019-0877-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 12/04/2018] [Indexed: 11/09/2022]
Abstract
Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium-tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules-several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.
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Valdivia MP, Veloso F, Stutman D, Stoeckl C, Mileham C, Begishev IA, Theobald W, Vescovi M, Useche W, Regan SP, Albertazzi B, Rigon G, Mabey P, Michel T, Pikuz SA, Koenig M, Casner A. X-ray backlighter requirements for refraction-based electron density diagnostics through Talbot-Lau deflectometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10G127. [PMID: 30399908 DOI: 10.1063/1.5039342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 09/08/2018] [Indexed: 06/08/2023]
Abstract
Talbot-Lau x-ray interferometers can map electron density gradients in High Energy Density (HED) samples. In the deflectometer configuration, it can provide refraction, attenuation, elemental composition, and scatter information from a single image. X-ray backlighters in Talbot-Lau deflectometry must meet specific requirements regarding source size and x-ray spectra, amongst others, to accurately diagnose a wide range of HED experiments. 8 keV sources produced in the high-power laser and pulsed power environment were evaluated as x-ray backlighters for Talbot-Lau x-ray deflectometry. In high-power laser experiments, K-shell emission was produced by irradiating copper targets (500 × 500 × 12.5 μm3 foils, 20 μm diameter wire, and >10 μm diameter spheres) with 30 J, 8-30 ps laser pulses and a 25 μm copper wire with a 60 J, 10 ps laser pulse. In the pulsed power environment, single (2 × 40 μm) and double (4 × 25 μm) copper x-pinches were driven at ∼1 kA/ns. Moiré fringe formation was demonstrated for all x-ray sources explored, and detector performance was evaluated for x-ray films, x-ray CCDs, and imaging plates in context of spatial resolution, x-ray emission, and fringe contrast.
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35
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Stoeckl C, Filkins T, Jungquist R, Mileham C, Pereira NR, Regan SP, Shoup MJ, Theobald W. Characterization of shaped Bragg crystal assemblies for narrowband x-ray imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10G124. [PMID: 30399777 DOI: 10.1063/1.5036525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/26/2018] [Indexed: 06/08/2023]
Abstract
X-ray imaging using shaped crystals in Bragg reflection is a powerful technique used in high-energy-density physics experiments. The characterization of these crystal assemblies with conventional x-ray sources is very difficult because of the required angular resolution of the order of ∼10 μrad and the narrow bandwidth of the crystal. The 10-J, 1-ps Multi-Terawatt (MTW) laser at the Laboratory for Laser Energetics was used to characterize a set of Bragg crystal assemblies. The small spot size (of the order of 5 μm) and the high power (>1018 W/cm2) of this laser make it possible to measure the spatial resolution at the intended photon energy. A set of six crystals from two different vendors was checked on MTW, showing an unexpectedly large variation in spatial resolution of up to a factor of 4.
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Theobald W, Sorce C, Bedzyk M, Ivancic ST, Marshall FJ, Stoeckl C, Shah RC, Lawrie M, Regan SP, Sangster TC, Campbell EM, Hilsabeck TJ, Englehorn K, Kilkenny JD, Morris D, Chung TM, Hares JD, Dymoke-Bradshaw AKL, Bell P, Celeste J, Carpenter AC, Dayton M, Bradley DK, Jackson MC, Pickworth L, Nagel SR, Rochau G, Porter J, Sanchez M, Claus L, Robertson G, Looker Q. The single-line-of-sight, time-resolved x-ray imager diagnostic on OMEGA. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10G117. [PMID: 30399700 DOI: 10.1063/1.5036767] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
The single-line-of-sight, time-resolved x-ray imager (SLOS-TRXI) on OMEGA is one of a new generation of fast-gated x-ray cameras comprising an electron pulse-dilation imager and a nanosecond-gated, burst-mode, hybrid complementary metal-oxide semiconductor sensor. SLOS-TRXI images the core of imploded cryogenic deuterium-tritium shells in inertial confinement fusion experiments in the ∼4- to 9-keV photon energy range with a pinhole imager onto a photocathode. The diagnostic is mounted on a fixed port almost perpendicular to a 16-channel, framing-camera-based, time-resolved Kirkpatrick-Baez microscope, providing a second time-gated line of sight for hot-spot imaging on OMEGA. SLOS-TRXI achieves ∼40-ps temporal resolution and better than 10-μm spatial resolution. Shots with neutron yields of up to 1 × 1014 were taken without observed neutron-induced background signal. The implosion images from SLOS-TRXI show the evolution of the stagnating core.
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MacDonald MJ, Saunders AM, Falcone RW, Theobald W, Landen OL, Döppner T. Developing a long-duration Zn K- α source for x-ray scattering experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10F109. [PMID: 30399805 DOI: 10.1063/1.5039365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
We are developing a long-duration K-α x-ray source at the Omega laser facility. Such sources are important for x-ray scattering measurements at small scattering angles where high spectral resolution is required. To date, He-α x-ray sources are the most common probes in scattering experiments, using ns-class lasers to heat foils to keV temperatures, resulting in K-shell emission from He-like charge states. The He-α spectrum can be broadened by emission from multiple charge states and lines (e.g., He-like, Li-like, Be-like). Here, we combine the long duration of He-α sources with the narrow spectral bandwidth of cold K-α emission. A Ge foil is irradiated by the Omega laser, producing principally Ge He-α emission, which pumps Zn K-α emission at 8.6 keV from a nearby Zn layer. Using this technique, we demonstrate a long-duration Zn K-α source suitable for scattering measurements. Our experimental results show a 60% reduction in spectral bandwidth compared to a standard Zn He-α source, significantly improving the measurement precision of scattering experiments with small inelastic shifts.
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Engelhorn K, Hilsabeck TJ, Kilkenny J, Morris D, Chung TM, Dymoke-Bradshaw A, Hares JD, Bell P, Bradley D, Carpenter AC, Dayton M, Nagel SR, Claus L, Porter J, Rochau G, Sanchez M, Ivancic S, Sorce C, Theobald W. Sub-nanosecond single line-of-sight (SLOS) x-ray imagers (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10G123. [PMID: 30399697 DOI: 10.1063/1.5039648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/24/2018] [Indexed: 06/08/2023]
Abstract
A new generation of fast-gated x-ray framing cameras have been developed that are capable of capturing multiple frames along a single line-of-sight with 30 ps temporal resolution. The instruments are constructed by integrating pulse-dilation electron imaging with burst mode hybrid-complimentary metal-oxide-semiconductor sensors. Two such instruments have been developed, characterized, and fielded at the National Ignition Facility and the OMEGA laser. These instruments are particularly suited for advanced x-ray imaging applications in Inertial Confinement Fusion and High energy density experiments. Here, we discuss the system architecture and the techniques required for tuning the instruments to achieve optimal performance. Characterization results are also presented along with planned future improvements to the design.
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Giraldez EM, Vu M, Hoppe ML, Losbanos E, Ravelo N, Greenwood A, Schoff M, Mauldin MP, Fitzsimmons P, Farrell MP, Theobald W. Fabrication of the Metal Particle in Plastic Bead Target for the LLE Ultra-Strong-Spherical Shock Campaign. FUSION SCIENCE AND TECHNOLOGY 2018. [DOI: 10.1080/15361055.2017.1389604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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Ceurvorst L, Savin A, Ratan N, Kasim MF, Sadler J, Norreys PA, Habara H, Tanaka KA, Zhang S, Wei MS, Ivancic S, Froula DH, Theobald W. Channel optimization of high-intensity laser beams in millimeter-scale plasmas. Phys Rev E 2018; 97:043208. [PMID: 29758617 DOI: 10.1103/physreve.97.043208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Indexed: 06/08/2023]
Abstract
Channeling experiments were performed at the OMEGA EP facility using relativistic intensity (>10^{18}W/cm^{2}) kilojoule laser pulses through large density scale length (∼390-570 μm) laser-produced plasmas, demonstrating the effects of the pulse's focal location and intensity as well as the plasma's temperature on the resulting channel formation. The results show deeper channeling when focused into hot plasmas and at lower densities, as expected. However, contrary to previous large-scale particle-in-cell studies, the results also indicate deeper penetration by short (10 ps), intense pulses compared to their longer-duration equivalents. This new observation has many implications for future laser-plasma research in the relativistic regime.
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Regan SP, Goncharov VN, Sangster TC, Campbell EM, Betti R, Anderson KS, Bernat T, Bose A, Boehly TR, Bonino MJ, Cao D, Chapman R, Collins TJB, Craxton RS, Davis AK, Delettrez JA, Edgell DH, Epstein R, Farrell M, Forrest CJ, Frenje JA, Froula DH, Johnson MG, Gibson C, Glebov VY, Greenwood A, Harding DR, Hohenberger M, Hu SX, Huang H, Hund J, Igumenshchev IV, Jacobs-Perkins DW, Janezic RT, 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, Petta N, Radha PB, Rosenberg MJ, Schmitt AJ, Schmitt MJ, Schoff M, Seka W, Shmayda WT, Shoup MJ, Shvydky A, Solodov AA, Stoeckl C, Sweet W, Taylor C, Taylor R, Theobald W, Ulreich J, Wittman MD, Woo KM, Zuegel JD. The National Direct-Drive Program: OMEGA to the National Ignition Facility. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.1080/15361055.2017.1397487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shang WL, Betti R, Hu SX, Woo K, Hao L, Ren C, Christopherson AR, Bose A, Theobald W. Electron Shock Ignition of Inertial Fusion Targets. PHYSICAL REVIEW LETTERS 2017; 119:195001. [PMID: 29219482 DOI: 10.1103/physrevlett.119.195001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Indexed: 06/07/2023]
Abstract
It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ∼10^{16} W/cm^{2}.
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Valdivia MP, Stutman D, Stoeckl C, Mileham C, Begishev IA, Theobald W, Bromage J, Regan SP, Klein SR, Muñoz-Cordovez G, Vescovi M, Valenzuela-Villaseca V, Veloso F. Publisher's Note: "Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)" [Rev. Sci. Instrum. 87, 11D501 (2016)]. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11F901. [PMID: 27910458 DOI: 10.1063/1.4961297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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Nilson PM, Ehrne F, Mileham C, Mastrosimone D, Jungquist RK, Taylor C, Stillman CR, Ivancic ST, Boni R, Hassett J, Lonobile DJ, Kidder RW, Shoup MJ, Solodov AA, Stoeckl C, Theobald W, Froula DH, Hill KW, Gao L, Bitter M, Efthimion P, Meyerhofer DD. A high-resolving-power x-ray spectrometer for the OMEGA EP Laser (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D504. [PMID: 27910626 DOI: 10.1063/1.4961076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A high-resolving-power x-ray spectrometer has been developed for the OMEGA EP Laser System based on a spherically bent Si [220] crystal with a radius of curvature of 330 mm and a Spectral Instruments (SI) 800 Series charge-coupled device. The instrument measures time-integrated x-ray emission spectra in the 7.97- to 8.11-keV range, centered on the Cu Kα1 line. To demonstrate the performance of the spectrometer under high-power conditions, Kα1,2 emission spectra were measured from Cu foils irradiated by the OMEGA EP laser with 100-J, 1-ps pulses at focused intensities above 1018 W/cm2. The ultimate goal is to couple the spectrometer to a picosecond x-ray streak camera and measure temperature-equilibration dynamics inside rapidly heated materials. The plan for these ultrafast streaked x-ray spectroscopy studies is discussed.
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Valdivia MP, Stutman D, Stoeckl C, Mileham C, Begishev IA, Theobald W, Bromage J, Regan SP, Klein SR, Muñoz-Cordovez G, Vescovi M, Valenzuela-Villaseca V, Veloso F. Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D501. [PMID: 27910439 DOI: 10.1063/1.4959158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.
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Stoeckl C, Theobald W, Regan SP, Romanofsky MH. Calibration of a time-resolved hard-x-ray detector using radioactive sources. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E323. [PMID: 27910320 DOI: 10.1063/1.4960599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.
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Regan SP, Goncharov VN, Igumenshchev IV, Sangster TC, Betti R, Bose A, Boehly TR, Bonino MJ, Campbell EM, Cao D, Collins TJB, 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, Zuegel JD. Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA. PHYSICAL REVIEW LETTERS 2016; 117:025001. [PMID: 27447511 DOI: 10.1103/physrevlett.117.025001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Indexed: 06/06/2023]
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.
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Bose A, Woo KM, Betti R, Campbell EM, Mangino D, Christopherson AR, McCrory RL, Nora R, Regan SP, Goncharov VN, Sangster TC, Forrest CJ, Frenje J, Gatu Johnson M, Glebov VY, Knauer JP, Marshall FJ, Stoeckl C, Theobald W. Core conditions for alpha heating attained in direct-drive inertial confinement fusion. Phys Rev E 2016; 94:011201. [PMID: 27575069 DOI: 10.1103/physreve.94.011201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Indexed: 06/06/2023]
Abstract
It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.
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Sawada H, Fujioka S, Hosoda T, Zhang Z, Arikawa Y, Nagatomo H, Nishimura H, Sunahara A, Theobald W, Patel PK, Beg FN. Development of 4.5 keV monochromatic X-ray radiography using the high-energy, picosecond LFEX laser. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/717/1/012112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Valdivia MP, Stutman D, Stoeckl C, Theobald W, Mileham C, Begishev IA, Bromage J, Regan SP. An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:023505. [PMID: 26931847 DOI: 10.1063/1.4941441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 01/24/2016] [Indexed: 06/05/2023]
Abstract
X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 10(23) cm(-3) in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of <8%. The 50 ± 15 μm spatial resolution achieved across the full field of view was found to be limited by the x-ray source-size, similar to conventional radiography.
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