Processing of spectrally resolved x-ray images of inertial confinement fusion implosion cores recorded with multimonochromatic x-ray imagers

Nagayama, Taisuke; Mancini, Roberto; Florido, R.; Tommasini, R.; Koch, J. A.; Delettrez, J. A.; Regan, S. P.; Smalyuk, V. A.

doi:10.1063/1.3580513

Cited by 22 publications

(33 citation statements)

References 29 publications

(50 reference statements)

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“…On one hand, the appropriate case shown in Figure 2 has w = 8 pixels. Thus, eight pixel columns are needed to fully reconstruct the image, which correspond to 15 eV for this particular dataset based on the extracted spectral axis [9] . Thus, the whole image can be reconstructed with a much narrower width than the spectral linewidth, where its FWHM is approximately 60 eV.…”

Section: Pha Design and Image Reconstructionmentioning

confidence: 99%

“…For example, Figure 2(b) shows an image reconstructed from one pixel column of the MMI data at the He-β line center (i.e., the orange line). Each pixel along this column is relocated into a single common image plane based on the position relative to its nearest image centers [9] . This single column provides strips of object spatial information that are uniformly separated over the image plane.…”

Section: Pha Design and Image Reconstructionmentioning

confidence: 99%

“…By processing MMI data, one can extract narrow-band images (i.e., intensity images of narrow spectral ranges), spaceintegrated spectra [7][8][9] and 2D space-resolved spectra [10] . Spectroscopic analysis of the images and spectra extracted from the MMI data can provide a variety of approaches to constrain the ICF plasma spatial structure in electron temperature, T e , and electron density, n e .…”

Section: Introductionmentioning

confidence: 99%

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An important criterion for reliable multi-monochromatic x-ray imager diagnostics and its impact on the reconstructed images

Nagayama

Mancini

Mayes

et al. 2015

High Pow Laser Sci Eng

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Temperature and density asymmetry diagnosis is critical to advance inertial confinement fusion (ICF) science. A multimonochromatic x-ray imager, MMI, records the spectral signature from an ICF implosion core with time resolution, 2D spatial resolution and spectral resolution. While narrow-band images and 2D space-resolved spectra from the MMI data constrain the temperature and the density spatial structure of the core, the accuracy of the images and the spectra highly depends on the quality of the MMI data and the processing tools. Here, we synthetically investigate the criterion for reliable MMI diagnostics and its effects on the accuracy of the reconstructed images. The pinhole array tilt determines the object spatial sampling efficiency and the minimum reconstruction width, w. When the spectral width associated with w is significantly narrower than the spectral linewidth, the line images reconstructed from the MMI data become reliable. The MMI setup has to be optimized for every application to meet this criterion for reliable ICF diagnostics.

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Section: Pha Design and Image Reconstructionmentioning

confidence: 99%

Section: Pha Design and Image Reconstructionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An important criterion for reliable multi-monochromatic x-ray imager diagnostics and its impact on the reconstructed images

Nagayama

Mancini

Mayes

et al. 2015

High Pow Laser Sci Eng

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“…Finally, we compute the spectrum associated with this sub-region using the technique discussed in Ref. [11]. The resultant spectrum shown in Fig.…”

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confidence: 99%

“…This approximation was tested by comparing with results from the self-consistent solution of atomic kinetics and radiation transport equation for the relevant plasma size and conditions [17]. The opacity effect in the emergent spectra is taken into account by integrating the radiation transport equation along a uniform chord, i: i is the chord length estimated by the implosion core volume extracted from the MMI data [11]. A global optimization, GALM, which consists of a genetic algorithm (GA) followed up by a Levenberg-Marquardt non-linear least squares minimization (LM) [18], was used to objectively find the optimal T e and n e of the region that produce the best fits to the space-resolved spectrum.…”

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confidence: 99%

Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

et al. 2014

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Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional spaceresolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.Inertial confinement fusion (ICF) is an approach that utilizes laser produced ablation pressure to compress a millimeter-sized spherical shell capsule containing fuel (e.g., deuterium and tritium) and drive the fuel temperature and density to conditions suitable for ignition [1]. The key is a spherically symmetric and stable compression. While state-of-the-art hydrodynamics simulations have been used to design ignition implosions, the challenge of achieving a symmetric implosion experimentally has thus far prevented ICF from reaching the conditions required for successful ignition [2]. Hence, measuring the spatial asymmetry in the temperature and density distributions in the implosion core is crucial for understanding how to make it more symmetric.Several diagnostics were developed in the last few decades in order to investigate implosion core conditions. K-shell line emission spectroscopy using Ar as a tracer has proved to be a powerful tool to extract spaceaveraged electron temperature, T e , and density, n e [3-5]. However, two-dimensional (2-D) space-resolved spectra have never been extracted to study the asymmetries of T e and n e structures in the implosion core. X-ray pinhole imaging of ICF implosion cores has been used to study the shape and size of the core and, in particular, to characterize deviations from spherical symmetry [6,7]. Nevertheless, these images do not reveal the implosion asymmetries in T e and n e distributions.This Letter describes a new spectroscopic method that combines the ideas of Ar tracer spectroscopy and pinhole imaging to extract implosion core images in T e and n e without making symmetry assumptions. These pinhole images are extracted by analyzing a collection of 2-D space-resolved spectra obtained from an array of spectrally resolved core images. The direct measurement of temperature and density asymmetries in the core provides stringent constraints on what actually happens in implosion experiments and can be used to benchmark hydrodynamic simulations. The discussion here focuses on the application to ICF implosion core conditions; nevertheless, the ideas are general. The extraction and analysis of space-resolved spectra from spectrally resolved pinhole images opens up new possibilities for x-ray spectroscopy of high-energy density plasmas.The spectroscopic data were recorded in a series of Ar-doped ICF implosion experiments performed at the Omega Laser ...

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FESTR: Finite-Element Spectral Transfer of Radiation spectroscopic modeling and analysis code

Hakel

2016

Computer Physics Communications

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Processing of spectrally resolved x-ray images of inertial confinement fusion implosion cores recorded with multimonochromatic x-ray imagers

Cited by 22 publications

References 29 publications

An important criterion for reliable multi-monochromatic x-ray imager diagnostics and its impact on the reconstructed images

An important criterion for reliable multi-monochromatic x-ray imager diagnostics and its impact on the reconstructed images

Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

FESTR: Finite-Element Spectral Transfer of Radiation spectroscopic modeling and analysis code

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