Absorption experiments on x-ray-heated mid-<i>Z</i>constrained samples

Perry, T. S.; Springer, P. T.; Fields, D. F.; Bach, Dieter; Serduke, F. J. D.; Iglesias, Carlos A.; Rogers, F. J.; Nash, J. K.; Chen, M. H.; Wilson, B. G.; Goldstein, W. H.; Rozsynai, B.; Ward, Richard A.; Kilkenny, J. D.; Doyas, R.J.; Silva, L. B. Da; Back, C. A.; Cauble, R.; Davidson, Steven J.; Foster, J. M.; Smith, C.; Bar‐Shalom, A.; Lee, R. W.

doi:10.1103/physreve.54.5617

Cited by 118 publications

(47 citation statements)

References 31 publications

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“…Using this technique, we have been able to accurately characterise the Al back lighter and perform transmission measurements using a laser system with a high reproducibility (±10%) on a shot to shot basis. A number of issues need to be addressed to obtain high accuracy opacity information [23]. Simulations have demonstrated using this technique results in large temperature and density gradients in the axial and radial direction which would have to be accurately measured.…”

Section: Discussionmentioning

confidence: 99%

X-ray back-lighter characterization for iron opacity measurements using laser-produced aluminium K-alpha emission

Rossall

Gartside

Chaurasia

et al. 2010

J. Phys. B: At. Mol. Opt. Phys.

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Aluminium K α emission (1.5 keV) produced by an 8 J, 500 ps, Nd:Glass laser incident at 45° onto a layered target of 0.8 µm thick aluminium (front side) and 1µm thick iron (back side) has been used to probe the opacity of iron plasma. Source broadened spectroscopy and continuum emission analysis shows that whole beam self focussing within the aluminium plasma results in a two temperature spatial distribution. Thermal conduction from the laser-irradiated aluminium into the iron layer, enhanced by the whole beam self focusing, results in iron at a temperature of ~ 10 -150 eV. The iron opacity at photon energy of 1.5 keV is shown to be strongly modified from cold values in agreement with IMP code opacities. Results presented here represent a feasibility study to seed future work using table top laser systems for plasma opacity experiments.

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Section: Discussionmentioning

confidence: 99%

X-ray back-lighter characterization for iron opacity measurements using laser-produced aluminium K-alpha emission

Rossall

Gartside

Chaurasia

et al. 2010

J. Phys. B: At. Mol. Opt. Phys.

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“…Conventional transmission measurements [27] require a back-lighter source significantly brighter than the sample self-emission. At temperatures > 200eV such a back-lighter has not been developed and so high temperature measurements of spectral structure are restricted to emission measurements at present.…”

Section: Measurements Of Emissivity In Hot Dense Plasmamentioning

confidence: 99%

Measurements of plasma spectra from hot dense elements and mixtures at conditions relevant to the solar radiative zone

Hoarty¹,

Hill²,

Beiersdörfer³

et al. 2017

AIP Conference Proceedings

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Abstract. X-ray emission spectroscopy has been used to study hot dense plasmas produced using high power laser irradiation of dot samples buried in low Z foils of plastic or diamond. By combining a high contrast short pulse (picosecond timescale) laser beam operating in second harmonic with long pulse (nanosecond timescale) laser beams in third harmonic, and with pulse shaping of the long pulse beams, a range of plasma temperatures from 400eV up to 2.5keV and electron densities from 5e22 up to 1e24/cc have been accessed. Examples are given of measurements of dense plasma effects such as ionization potential depression and line-broadening from the K-shell emission spectra of a range of low Z elements and mixtures and compared to model prediction. Detailed spectra from measurements of the Lshell emission from mid-Z elements are also presented for an example spectrum of germanium. These data are at conditions found in stellar interiors and in particular in the radiative zone of the sun. The plasma conditions are inferred from comparison of the measured spectra to detailed modeling using atomic kinetics and spectral synthesis codes.

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“…The prior experiments used 10-40 kJ from the HELEN, Nova or Omega lasers to heat 1.0-2.5 mm diameter hohlraums up to ∼100 eV (e.g. Davidson et al 1988;Perry et al 1996). The choice of axial rather than orthogonal backlighting is motivated by a desire to retain twodimensional (2-D) cylindrical geometry to simplify integrated target calculations, and also the fact that axial backlighting on NIF can be accomplished with a much simpler laser-target configuration.…”

Section: Experimental Approachmentioning

confidence: 99%

“…The NIF design uses the point-projection approach to opacity measurements, in which a very small, very brief, broadband X-ray source projects an absorption spectrum onto a time-integrated detector (Perry et al 1996). In this technique, the X-ray transmission, T, of a uniform sample follows the relation…”

Section: Experimental Approachmentioning

confidence: 99%

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Conceptual design of initial opacity experiments on the national ignition facility

et al. 2017

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Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative-convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures 150 eV and electron densities 7 × 10 21 cm −3. The iron will be probed using continuum X-rays emitted in a ∼200 ps, ∼200 µm diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design, 2/3 of the NIF beams deliver 500 kJ to the ∼6 mm diameter hohlraum, and the remaining 1/3 directly drive the CH capsule with 200 kJ. Calculations indicate this capsule backlighter should outshine the iron sample, delivering a point-projection transmission opacity measurement to a time-integrated X-ray spectrometer viewing down the hohlraum axis. Preliminary experiments to develop the backlighter and hohlraum are underway, informing simulated measurements to guide the final design.

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Absorption experiments on x-ray-heated mid-Zconstrained samples

Cited by 118 publications

References 31 publications

X-ray back-lighter characterization for iron opacity measurements using laser-produced aluminium K-alpha emission

X-ray back-lighter characterization for iron opacity measurements using laser-produced aluminium K-alpha emission

Measurements of plasma spectra from hot dense elements and mixtures at conditions relevant to the solar radiative zone

Conceptual design of initial opacity experiments on the national ignition facility

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