Progress toward the development and testing of source reconstruction methods for NIF neutron imaging

Loomis, Eric; Grim, G.; Wilde, C. H.; Wilson, D. C.; Morgan, G. L.; Wilke, M. D.; Tregillis, I. L.; Merrill, F. E.; Clark, Deborah J.; Finch, Joshua P.; Fittinghoff, D. N.; Bower, D.

doi:10.1063/1.3492384

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…The triangular shape and extended nature of the pinholes result in distortions that vary across the field of view, often referred to as a non-stationary point spread function. [7][8][9] Because of the non-stationary nature of the point spread function it is important to know the location of the pinhole axis with respect to the neutron source center in order to accurately remove the distortions introduced by the pinhole or penumbral imaging. The aperture array is aligned to the source location with an accuracy of ∼±100 μm, which is sufficient to place the source within the field of view, but provides insufficient knowledge to appropriately remove the nonstationary image distortions.…”

Section: Introductionmentioning

confidence: 99%

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Self characterization of a coded aperture array for neutron source imaging

Volegov

Danly

Fittinghoff

et al. 2014

Review of Scientific Instruments

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The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.

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Section: Introductionmentioning

confidence: 99%

“…(7) and the large number of optimization parameters(19), it is convenient in practice to split solving Eq. (2) into two independent problems:(a) given a set of parameters of neutron sources distributions S = {s j } N s 1 , find alignment parameters of each aperture in the array, excluding the "anchor" aperture: a i = arg max a i l({A, D, S}), i = {1, .…”

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confidence: 99%

Self characterization of a coded aperture array for neutron source imaging

Volegov

Danly

Fittinghoff

et al. 2014

Review of Scientific Instruments

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Super-resolution image reconstruction of a neutron thick pinhole imaging system using image denoiser prior based on half quadratic splitting method

Li,

Sheng,

Duan

et al. 2024

Nuclear Instruments and Methods in Physics Research Section A:

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Modeling the National Ignition Facility neutron imaging system

Wilson

Grim

Tregillis

et al. 2010

Review of Scientific Instruments

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Numerical modeling of the neutron imaging system for the National Ignition Facility (NIF), forward from calculated target neutron emission to a camera image, will guide both the reduction of data and the future development of the system. Located 28 m from target chamber center, the system can produce two images at different neutron energies by gating on neutron arrival time. The brighter image, using neutrons near 14 MeV, reflects the size and symmetry of the implosion "hot spot." A second image in scattered neutrons, 10-12 MeV, reflects the size and symmetry of colder, denser fuel, but with only ∼1%-7% of the neutrons. A misalignment of the pinhole assembly up to ±175 μm is covered by a set of 37 subapertures with different pointings. The model includes the variability of the pinhole point spread function across the field of view. Omega experiments provided absolute calibration, scintillator spatial broadening, and the level of residual light in the down-scattered image from the primary neutrons. Application of the model to light decay measurements of EJ399, BC422, BCF99-55, Xylene, DPAC-30, and Liquid A suggests that DPAC-30 and Liquid A would be preferred over the BCF99-55 scintillator chosen for the first NIF system, if they could be fabricated into detectors with sufficient resolution.

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Progress toward the development and testing of source reconstruction methods for NIF neutron imaging

Cited by 8 publications

References 9 publications

Self characterization of a coded aperture array for neutron source imaging

Self characterization of a coded aperture array for neutron source imaging

Super-resolution image reconstruction of a neutron thick pinhole imaging system using image denoiser prior based on half quadratic splitting method

Modeling the National Ignition Facility neutron imaging system

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