Replicating the Z iron opacity experiments on the NIF

Perry, T. S.; Heeter, R. F.; Opachich, Y. P.; Ross, P. W.; Kline, J. L.; Flippo, K. A.; Sherrill, M. E.; Dodd, E. S.; DeVolder, B.G.; Cárdenas, T.; Archuleta, T. N.; Craxton, R. S.; Zhang, R.; McKenty, P. W.; García, Emma Moreno; Huffman, E.; King, J. A.; Ahmed, M. F.; Emig, J.; Ayers, S.; Barrios, M. A.; May, Mark; Schneider, M. B.; Liedahl, D. A.; Wilson, B. G.; Urbatsch, Todd; Iglesias, Carlos A.; Bailey, J. E.; Rochau, G. A.

doi:10.1016/j.hedp.2017.05.006

Cited by 30 publications

(15 citation statements)

References 13 publications

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“…Section 7 draws summarizes and discusses future work. Figure 1 (left) illustrates the experimental approach used at NIF [3,4]. Opacity experiments have many detailed requirements [7,8], but the heart of the measurement is a fully calibrated X-ray transmission spectrum obtained through a uniform sample with known composition, areal density, electron density, and temperature.…”

Section: Structure Of the Papermentioning

confidence: 99%

“…Opacity experiments have many detailed requirements [7,8], but the heart of the measurement is a fully calibrated X-ray transmission spectrum obtained through a uniform sample with known composition, areal density, electron density, and temperature. The center of the NIF experiment is a 'McFee-Apollo' shaped gold hohlraum [4,9,10] containing a 12-micron thick plastic foil on the midplane, as illustrated in Figure 1 (right). Embedded in the 4 mm diameter parylene-N plastic foil is a rectangular 1.0 × 2.0 mm patch of co-deposited iron and magnesium [10].…”

Section: Structure Of the Papermentioning

confidence: 99%

“…Several years' research by various teams into possible systematic errors in the experiment or inadequate approximations in various opacity theories have not resolved the disagreement. To address this divergence, an entirely different opacity experimental 'platform' has been developed [3,4] on the National Ignition Facility (NIF) laser system [5,6]. The current goal of the NIF campaign is to independently replicate the Z measurements at 156 eV, including quantification of the uncertainties, to validate the NIF platform.…”

Section: Introductionmentioning

confidence: 99%

“…Five separate hohlraum designs were tested before the McFee-Apollo concept succeeded in providing sufficiently low X-ray Atoms 2018, 6, 57 3 of 20 backgrounds for axial absorption spectroscopy of the sample. Further details about the hohlraum design, fabrication, and modeling are available [4,9,10].…”

Section: Introduction To the Nif Opacity Experimentsmentioning

confidence: 99%

“…Atoms 2018, 6, x FOR PEER REVIEW 3 of 20 low X-ray backgrounds for axial absorption spectroscopy of the sample. Further details about the hohlraum design, fabrication, and modeling are available [4,9,10].…”

Section: Introduction To the Nif Opacity Experimentsmentioning

confidence: 99%

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Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Heeter

Perry

Johns

et al. 2018

Atoms

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Discrepancies exist between theoretical and experimental opacity data for iron, at temperatures 180-195 eV and electron densities near 3 × 10 22 /cm 3 , relevant to the solar radiative-convective boundary. Another discrepancy, between theory and helioseismic measurements of the boundary's location, would be ameliorated if the experimental opacity is correct. To address these issues, this paper details the first results from new experiments under development at the National Ignition Facility (NIF), using a different method to replicate the prior experimental conditions. In the NIF experiments, 64 laser beams indirectly heat a plastic-tamped rectangular iron-magnesium sample inside a gold cavity. Another 64 beams implode a spherical plastic shell to produce a continuum X-ray flash which backlights the hot sample. An X-ray spectrometer records the transmitted X-rays, the unattenuated X-rays passing around the sample, and the sample's self-emission. From these data, X-ray transmission spectra are inferred, showing Mg K-shell and Fe L-shell X-ray transitions from plasma at a temperature of~150 eV and electron density of~8 × 10 21 /cm 3 . These conditions are similar to prior Z measurements which agree better with theory. The NIF transmission data show statistical uncertainties of 2-10%, but various systematic uncertainties must be addressed before pursuing quantitative comparisons. The paths to reduction of the largest uncertainties are discussed. Once the uncertainty is reduced, future NIF experiments will probe higher temperatures (170-200 eV) to address the ongoing disagreement between theory and Z data.

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Section: Structure Of the Papermentioning

confidence: 99%

Section: Structure Of the Papermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introduction To the Nif Opacity Experimentsmentioning

confidence: 99%

Section: Introduction To the Nif Opacity Experimentsmentioning

confidence: 99%

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Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Heeter

Perry

Johns

et al. 2018

Atoms

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Simultaneous X-ray and XUV absorption measurements in nickel laser-produced plasma close to LTE

Dozières

Thais

Bastiani-Ceccotti

et al. 2019

High Energy Density Physics

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We present an experiment performed in 2016 at the LULI2000 laser facility in which X-ray and XUV absorption structures of nickel hot plasmas were measured simultaneously. Such experiments may provide stringent tests of the accuracy of plasma atomic-physics codes used to the modeling of plasmas close to local thermodynamic equilibrium. The experimental setup relies on a symmetric heating of the sample foil by two gold hohlraums in order to reduce the spatial gradients. The plasma conditions are characterized by temperatures between 10 and 20 eV and densities of the order of 10 −3 g/cm 3-10 −2 g/cm 3. For the X-ray part, we investigate the 2p-3d and 2p-4d transitions, and for the XUV part, we recorded the Δn = 0 (n = 3) transitions, which present a high sensitivity to plasma temperature. These latter transitions are of particular interest because, in mid-Z plasmas, they dominate the Planck and Rosseland mean opacities. Measured spectra are compared to calculations performed using the hybrid opacity code SCO-RCG and the Flexible Atomic Code (FAC). The influence of a spectator electron on the calculated spectra is analyzed using the latter code.

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A proposal to measure iron opacity at conditions close to the solar convective zone-radiative zone boundary

Hoarty

Morton

Jeffery

et al. 2019

High Energy Density Physics

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Replicating the Z iron opacity experiments on the NIF

Cited by 30 publications

References 13 publications

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Simultaneous X-ray and XUV absorption measurements in nickel laser-produced plasma close to LTE

A proposal to measure iron opacity at conditions close to the solar convective zone-radiative zone boundary

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