Quasi-monochromatic, projection radiography of dense laser driven spherical targets

Lewis, Ciaran; Mcglinchey, J.

doi:10.1016/0030-4018(85)90327-x

Cited by 51 publications

(14 citation statements)

References 8 publications

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“…The reproducibility encompasses the x-ray heating of the sample, the sample fabrication, the backlight absolute intensity and spectrum, the spectrometer efficiency ͑e.g., crystal reflectivity͒ and the detector response ͑e.g., film processing reproducibility͒. A powerful alternative method known as point projection backlighting 21,22 provides the required data in a single experiment ͑Fig. 8͒.…”

Section: Experimental Methods and Historical Overviewmentioning

confidence: 99%

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Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmas

et al. 2009

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Theoretical opacities are required for calculating energy transport in plasmas. In particular, understanding stellar interiors, inertial fusion, and Z pinches depends on the opacities of mid-atomic-number elements over a wide range of temperatures. The 150–300 eV temperature range is particularly interesting. The opacity models are complex and experimental validation is crucial. For example, solar models presently disagree with helioseismology and one possible explanation is inadequate theoretical opacities. Testing these opacities requires well-characterized plasmas at temperatures high enough to produce the ion charge states that exist in the sun. Typical opacity experiments heat a sample using x rays and measure the spectrally resolved transmission with a backlight. The difficulty grows as the temperature increases because the heating x-ray source must supply more energy and the backlight must be bright enough to overwhelm the plasma self-emission. These problems can be overcome with the new generation of high energy density (HED) facilities. For example, recent experiments at Sandia’s Z facility [M. K. Matzen et al., Phys. Plasmas 12, 055503 (2005)] measured the transmission of a mixed Mg and Fe plasma heated to 156±6 eV. This capability will also advance opacity science for other HED plasmas. This tutorial reviews experimental methods for testing opacity models, including experiment design, transmission measurement methods, accuracy evaluation, and plasma diagnostics. The solar interior serves as a focal problem and Z facility experiments illustrate the techniques.

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Section: Experimental Methods and Historical Overviewmentioning

confidence: 99%

“…[21][22][23] These measurements are conceptually straightforward: The sample thickness is measured after it is heated by the x-ray source and the density is obtained by comparing with measurements of the initial sample thickness performed prior to the experiment ͑Fig. 23͒.…”

Section: Plasma Diagnosticsmentioning

confidence: 99%

Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmas

et al. 2009

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“…The HELEN backlighter beam (50 J at 0.53-/im wavelength in a 200-ps pulse) is used to illuminate a small (typically 20 jum) diameter glass fiber target coated with approximately \-/im thickness of a rare-earth metal (neodymium in the case of the germanium sample experiment) chosen so that its laser-plasma emission spectrum falls in the spectral region of interest. This short-duration, near-point backlighting source, the heated sample, and an appropriate circular aperture are arranged together with a Bragg crystal spectrometer in the point-projection-spectroscopy geometry [9,10] so that the unattenuated and attenuated backlighter spectra, together with the overlying emission spectrum of the sample, may all be recorded simultaneously on x-ray sensitive film (Fig. 2).…”

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confidence: 99%

L-shell absorption spectrum of an open-M-shell germanium plasma: Comparison of experimental data with a detailed configuration-accounting calculation

et al. 1991

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The radiative opacity of a near local thermodynamic equilibrium, open-M-shell Ge plasma has been measured in the region of the 2p-3d and 2p-4d transition arrays, and is compared for the first time with the results of a detailed configuration-accounting calculation which includes an approximate treatment of term widths. The plasma was generated by radiation heating using thermal x radiation from a laserproduced gold plasma. Temperature and density were characterized in experiments which observed the absorption spectra of Al and Mg plasmas and by radiographic measurements of the expansion of the heated foil samples.

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“…5,6 A broadband x-ray source illuminates a sample that absorbs particular frequencies given its ionization state. The spectrum of radiation transmitted through the sample is measured, and the absorption lines of the sample are identified.…”

Section: Theorymentioning

confidence: 99%

A technique for measuring the propagation of a supersonic radiation front in foam via spatially resolved spectral imaging of a tracer layer

Taccetti

Keiter

Lanier

et al. 2012

Review of Scientific Instruments

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We present a technique for measuring the propagation of a supersonic radiation front in low-density foam, where the lack of motion of the objects in its wake makes it difficult to determine its location. We illuminate a thin tracer foil embedded in the foam with a broadband x-ray source, and measure its changing absorption of these x rays as it ionizes. We record both spatial and spectral information of the heated tracer, and thus obtain its ionization state as a function of distance along the front propagation direction. We extrapolate this information to determine the state of the foam and the location of the radiation front. We present the experimental configuration used to test this technique at the Omega laser facility along with experimental results.

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Quasi-monochromatic, projection radiography of dense laser driven spherical targets

Cited by 51 publications

References 8 publications

Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmas

Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmas

L-shell absorption spectrum of an open-M-shell germanium plasma: Comparison of experimental data with a detailed configuration-accounting calculation

A technique for measuring the propagation of a supersonic radiation front in foam via spatially resolved spectral imaging of a tracer layer

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