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

Nagayama, Taisuke; Mancini, Roberto; Mayes, Daniel; Tommasini, R.; Florido, R.

doi:10.1017/hpl.2015.25

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…While the MMI data reliability for other applications are beyond the scope of this article, the reliability depends on the criterion discussed in Ref. 13, which depends on the object size, MCP strip width, pinhole-array design, magnification, and line spectral width. Thus, as long as the MMI setup is similar, the object size is comparable, and the electron density is similar, the reliability of the images and spectra would be quantitatively similar to those discussed in this article.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…We create synthetic MMI data that satisfy the criterion discussed in Ref. 13. We assume a 100-µm-diameter spherical plasma of uniform conditions (T e = 1500 eV and n e = 1.5 × 10 24 cm −3 ).…”

Section: Quantitative Investigations Of Spatial and Spectral Resmentioning

confidence: 99%

“…However, this post-processing part is quite reliable as long as it satisfies the reliability criterion discussed in Ref. 13.…”

Section: Introductionmentioning

confidence: 99%

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Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

Nagayama

Mancini

Mayes

et al. 2015

Review of Scientific Instruments

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Temperature and density asymmetry diagnosis is critical to advance inertial confinement fusion (ICF) science. A multi-monochromatic x-ray imager (MMI) is an attractive diagnostic for this purpose. The MMI records the spectral signature from an ICF implosion core with time resolution, 2-D space resolution, and spectral resolution. While narrow-band images and 2-D space-resolved spectra from the MMI data constrain temperature and density spatial structure of the core, the accuracy of the images and spectra depends not only on the quality of the MMI data but also on the reliability of the post-processing tools. Here, we synthetically quantify the accuracy of images and spectra reconstructed from MMI data. Errors in the reconstructed images are less than a few percent when the space-resolution effect is applied to the modeled images. The errors in the reconstructed 2-D space-resolved spectra are also less than a few percent except those for the peripheral regions. Spectra reconstructed for the peripheral regions have slightly but systematically lower intensities by ∼6% due to the instrumental spatial-resolution effects. However, this does not alter the relative line ratios and widths and thus does not affect the temperature and density diagnostics. We also investigate the impact of the pinhole size variation on the extracted images and spectra. A 10% pinhole size variation could introduce spatial bias to the images and spectra of ∼10%. A correction algorithm is developed, and it successfully reduces the errors to a few percent. It is desirable to perform similar synthetic investigations to fully understand the reliability and limitations of each MMI application. C 2015 AIP Publishing LLC. [http://dx

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Section: Discussion and Summarymentioning

confidence: 99%

Section: Quantitative Investigations Of Spatial and Spectral Resmentioning

confidence: 99%

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Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

Nagayama

Mancini

Mayes

et al. 2015

Review of Scientific Instruments

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Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions

et al. 2016

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In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. These 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (Ne) = 8.5 × 1024 ± 2.5 × 1024 cm−3, and average areal density 〈ρR〉 = 86 ± 7 mg/cm2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. A new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ± 1 μm.

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Direct multiple monochromatic x-ray imaging with a pinhole array and a laterally graded multilayer mirror

Xu,

Wen,

et al. 2024

Review of Scientific Instruments

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Multiple monochromatic x-ray imaging (MMI) is a technique for diagnosing the emission spectra of tracer elements in laser-driven inertial confinement fusion experiments. This study proposes an MMI method that combines a simple pinhole array with a laterally graded multilayer mirror. The method directly obtains multiple monochromatic x-ray images by regulating the multilayer thickness in different mirror positions to compensate for the energy-broadening effect. This paper presents a comprehensive design scheme, the multilayer fabrication and experimental verification of the gradient MMI imaging performance. The experimental results show that the method achieves monochromatic imaging with a spectral resolution of ∼70–90 eV in several keV energy regions. This paper presents a practical diagnostic approach for directly and synchronously capturing the spatial, temporal, and spectral information of laser plasma x rays.

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

Cited by 6 publications

References 18 publications

Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions

Direct multiple monochromatic x-ray imaging with a pinhole array and a laterally graded multilayer mirror

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