Laboratory measurements of geometrical effects in the x-ray emission of optically thick lines for ICF diagnostics

Pérez-Callejo, G.; Jarrott, L. C.; Liedahl, D. A.; Marley, E. V.; Heeter, R. F.; Emig, J.; Foord, Mark; Widmann, K.; Jaquez, J.; Huang, H.; Rose, S. J.; Wark, J. S.; Schneider, M. B.

doi:10.1063/1.5096972

Cited by 9 publications

(15 citation statements)

References 54 publications

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“…This effect is also present in High Energy Density (HED) experiments [10,11] with the advantage that, contrary to most astrophysical cases, several LOS can be observed at once. In this way, the differences in spectra from all LOS can be linked to the optical depth, and from it, several plasma properties can be studied.…”

Section: Introductionmentioning

confidence: 97%

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

Pérez-Callejo

Wark

Rose

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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We present solutions of the radiative transfer equation for cylinders, hollow hemi-ellipsoidal shells and tori for a uniform plasma of fixed geometry. The radiative transfer equation is explicitly solved for two directions of emission, parallel and perpendicular to the axis of symmetry. The ratio between the fluxes in these two directions is also calculated and its use in measuring the frequency resolved opacity of the plasma is discussed. We find that the optimal geometry to use this ratio as an opacity measurement is a planar geometry.

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Section: Introductionmentioning

confidence: 97%

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

Pérez-Callejo

Wark

Rose

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…A buried layer platform has been developed in recent years at LLNL and LLE for this purpose [3][4][5] . The experimental results were presented in previous publications, and some aspects of the simulations were reported in 4 .…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic conditions in laser irradiated buried layer experiments

et al. 2020

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The calculation of open shell ionization level and radiative properties of materials in Non-Local Thermal Equilibrium (NLTE) is currently still a major challenge for any atomic model. The predictions of various NLTE atomic codes at these conditions still differ significantly. In recent years a new buried layer platform was developed at the Lawrence Livermore National Laboratory (LLNL) and the Laboratory for Laser Energetics (LLE). This platform is used to measure ionization distribution and emission of open L-shell, mid-Z ions and open M-shell, high-Z ions at NLTE conditions that are relevant in many laser plasma applications. These experiments offer a unique chance for benchmarking the atomic models. In order to perform these experiments a uniform well characterized plasma source is required. In this work we present 1D and 2D simulations of the experimental platform. These simulations were used for both the design and the analysis of the experiments. The simulations demonstrate the different phases of hydrodynamic evolution of the target, and identify the time windows in which uniform conditions can be achieved. A 1D expansion of the target was found to be adequate to describe the target's evolution for most of the experiment duration. The fast 1D simulations were compared with recent experimental results from the Omega laser facility. The sensitivity of the results to several modeling parameters such as the electron flux limiter and laser resonant absorption is reported.

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“…The thickness of the Sc/V disk has been exaggerated for clarity. [45,46], to date there has been no experimental validation of the important effect of resonant scattering in a controlled setting -i.e. within a plasma, uniform in density and temperature, and with a well-defined geometry simultaneously observed from the different relevant vantage points.…”

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confidence: 99%

“…For each target radius (125 and 175 µm), we took four data shots. More details on the experimental set-up are given in [46].…”

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confidence: 99%

“…As expected, given that the aspect ratio H/R is lower for targets R175, the w line is consistently more enhanced in these targets than in targets R125, although in both cases the LOS, and temperature and density conditions are the same (as shown in Figures 2a and 3). The line ratios have been obtained following a procedure identical to that described in [46], and the error bars in the figure come from the variations in the line ratios from different shots. Additionally, the gray region shows the line ratio that corresponds to an optically thin plasma.…”

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confidence: 99%

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Demonstration of Geometric Effects and Resonant Scattering in the X-Ray Spectra of High-Energy-Density Plasmas

et al. 2021

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In a plasma of sufficient size and density, photons emitted within the system have a probability of being re-absorbed and re-emitted multiple times -a phenomenon known in astrophysics as resonant scattering. This effect alters the ratio of optically-thick to optically thin lines, depending on the plasma geometry and viewing angle, and has significant implications for the spectra observed in a number of astrophysical scenarios, but has not previously been studied in a controlled laboratory plasma. We demonstrate the effect in the x-ray spectra emitted by cylindrical plasmas generated by high power laser irradiation, and the results confirm the geometrical interpretation of resonant scattering.

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Laboratory measurements of geometrical effects in the x-ray emission of optically thick lines for ICF diagnostics

Cited by 9 publications

References 54 publications

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

Hydrodynamic conditions in laser irradiated buried layer experiments

Demonstration of Geometric Effects and Resonant Scattering in the X-Ray Spectra of High-Energy-Density Plasmas

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