Investigation of a polychromatic tomography method for the extraction of the three-dimensional spatial structure of implosion core plasmas

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

doi:10.1063/1.4743017

Cited by 27 publications

(24 citation statements)

References 41 publications

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“…The spatial resolution is Δx ≈ 10µm, mainly limited by the pinhole size, and the spectral resolution power is λ/Δλ ≈ 150. The array of spectrally resolved images recorded with MMI is rich in information, and can be processed to produce broad-and narrow-band xray images integrated over a range of photon energies or centered on line transitions of the tracer element, respectively [23]. Three identical MMI instruments are available for fielding in direct-drive implosions at OMEGA.…”

Section: Methodsmentioning

confidence: 99%

“…More details about the instrument and data processing methods can be found in Refs. [19][20][21][22][23]. Other diagnostics fielded in the experiments included a neutron time-of-flight detector comprising a scintillator counter connected to a photomultiplier for total neutron yield measurements [24], a nuclear temporal diagnostic (NTD) [25] to measure the fusion reaction-rate time-history of the implosion and bang time (i.e., peak of the burn rate time-history), and a gated filtered (10mil Be and 0.5mil Ti), broadband x-ray imager (LFC) equipped with 10µm pinholes, six MCP's and capable of recording up to six images per MCP for a total of up to 36 images [26].…”

Section: Methodsmentioning

confidence: 99%

“…Specific target details for the shots discussed in this paper are shown in Table 2. Gated, spectrally resolved x-ray images were recorded with the MMI instruments available at OMEGA for fielding in direct-drive implosions [19][20][21][22][23]. The MMI imagers viewed the implosion along both equatorial and polar LOS.…”

Section: Methodsmentioning

confidence: 99%

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Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

et al. 2014

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We present spatially, temporally, and spectrally resolved narrow-and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to zero-order hydrodynamics. Equatorial view synthetic images obtained from post-processing a 2D hydrodynamic simulation are consistent with the experimental observation. Polar view images show a pentagonal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of these experiments not previously observed.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

et al. 2014

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“…These two results illustrate the versatility and potential of MMI space-resolved spectra analysis as well as the flexibility in the sub-region selection. Finally, the extraction and analysis of space-resolved spectra from MMI data discussed here also provides the basis to implement a polychromatic tomography method [18] to investigate the 3-D T e and n e distributions of laboratory high energy density plasmas, including ICF implosion cores.…”

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confidence: 99%

“…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. Since the GA is initialized by a random number generator, running it with different initial seeds for the same data checks the solution uniqueness.…”

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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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A Novel Three-Dimensional Asymmetric Reconstruction Method of Plasma

Wang

Jia

2017

Communications in Computer and Information Science

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Investigation of a polychromatic tomography method for the extraction of the three-dimensional spatial structure of implosion core plasmas

Abstract: Processing of spectrally resolved x-ray images of inertial confinement fusion implosion cores recorded with multimonochromatic x-ray imagers Journal of Applied Physics 109, 093303 (2011);

Cited by 27 publications

References 41 publications

Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

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

A Novel Three-Dimensional Asymmetric Reconstruction Method of Plasma

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