Quantitative characterization of inertial confinement fusion capsules using phase contrast enhanced x-ray imaging

Kozioziemski, B.; Koch, J. A.; Barty, Anton; Martz, H.E.; Lee, Ivan; Fezzaa, Kamel

doi:10.1063/1.1862764

Cited by 65 publications

(27 citation statements)

References 40 publications

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“…2(a). In addition, low magnification images are taken that provide an estimate of the total groove area by phase contrast enhanced imaging of groove defects [37]. This powerful technique has been shown to detect small but deep grooves in the part of the layer that is not diagnosed with images at standard magnification, see comparison between Fig.…”

Section: Inertial Confinement Fusion Targetsmentioning

confidence: 99%

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

et al. 2012

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The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 mega joules produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 µm diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 ± 3) µm, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 ± 0.09) g cm −2 result in fuel densities approaching 600 g cm −3 . The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 ± 0.1) keV that is measured with neutron time of flight spectra. Absolute neutron yields of (7.5 ± 0.1) × 10 14 have been recorded from the magnetic recoil spectrometer and nuclear activation diagnostics while gamma ray measurements provide the duration of nuclear activity of (170 ± 30) ps. These indirect-drive implosions result in the highest areal densities and neutron yields achieved on laser facilities to date. This achievement is the result of the first hohlraum and capsule tuning experiments where the stagnation pressures have been systematically increased by more than a factor of 10 by fielding low-entropy implosions through the control of radiation symmetry, small hot electron production, and proper shock timing. The stagnation pressure is above 100 Gbar resulting in high Lawson confinement parameters of P τ 10 atm s. Comparisons with radiation-hydrodynamic simulations indicate that the pressure is within a factor of three required for reaching ignition and high yield. This will be the focus of future higher-velocity implosions that will employ additional optimizations of hohlraum, capsule and laser pulse shape conditions.

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Section: Inertial Confinement Fusion Targetsmentioning

confidence: 99%

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

et al. 2012

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“…However, characterization of solid D-T layers inside the optically opaque beryllium shell has proven difficult. [12][13][14] It was recently suggested [15] and demonstrated [16,17] that solid D-T could be characterized using phase-contrast enhanced x-ray imaging. However, those early experiments could not resolve the fine scale roughness necessary to meet NIF characterization requirements.…”

Section: Inertial Confinement Fusion Experiments Such As Those At Thmentioning

confidence: 99%

Solid deuterium–tritium surface roughness in a beryllium inertial confinement fusion shell

et al. 2006

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Solid deuterium-tritium (D-T) fuel layers for inertial confinement fusion experiments were formed inside of a 2 mm diameter beryllium shell and were characterized using phase-contrast enhanced x-ray imaging.The solid D-T surface roughness is found to be 0.4 µm for modes 7-128 at 1.5 K below the melting temperature. The layer roughness is found to increase with decreasing temperature, in agreement with previous visible light characterization studies. However, phase-contrast enhanced x-ray imaging provides a more robust surface roughness measurement than visible light methods. The new x-ray imaging results demonstrate clearly that the surface roughness decreases with time for solid D-T layers held at 1.5 K below the melting temperature.

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“…[7] Models also demonstrate that the surface roughness can be accurately characterized. [7,10] Experiments at the Advanced Photon Source using surrogate plastic and foam shells verified that a rough surface could be imaged. [10] This paper describes characterization of actual solid D-T layers inside a Be(Cu) shell using a commercial micro-focus x-ray source.…”

Section: Introductionmentioning

confidence: 99%

“…[6,7] Phase-contrast enhanced imaging methods have been demonstrated for other materials with similar characteristics. [8][9][10][11][12][13][14][15] Recent advances in phase-contrast enhanced x-ray imaging using laboratory x-ray sources makes x-ray imaging of the solid D-T layer possible. [16][17][18] Calculations for phase-contrast x-ray imaging showed that the D-T surface should be rendered visible in the Be(Cu) shell using a micro-focus source.…”

Section: Introductionmentioning

confidence: 99%

X-ray imaging of cryogenic deuterium-tritium layers in a beryllium shell

Kozioziemski

Sater

Moody

et al. 2005

Journal of Applied Physics

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Solid deuterium-tritium (D-T) fuel layers inside copper-doped beryllium shells are robust inertial confinement fusion fuel pellets. This paper describes the first characterization of such layers using phase-contrast x-ray imaging. Good agreement is found between calculation and experimental contrast at the layer interfaces. Uniform solid D-T layers and their response to thermal asymmetries were measured in the Be(Cu) shell. The solid D-T redistribution time constant was measured to be 28 min in the Be(Cu) shell.

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Quantitative characterization of inertial confinement fusion capsules using phase contrast enhanced x-ray imaging

Cited by 65 publications

References 40 publications

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

Solid deuterium–tritium surface roughness in a beryllium inertial confinement fusion shell

X-ray imaging of cryogenic deuterium-tritium layers in a beryllium shell

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