Publications (5)24.84 Total impact
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Article: Iron-plasma transmission measurements at temperatures above 150 eV.
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ABSTRACT: Measurements of iron-plasma transmission at 156+/-6 eV electron temperature and 6.9+/-1.7 x 10(21) cm(-3) electron density are reported over the 800-1800 eV photon energy range. The temperature is more than twice that in prior experiments, permitting the first direct experimental tests of absorption features critical for understanding solar interior radiation transport. Detailed line-by-line opacity models are in excellent agreement with the data.Physical Review Letters 01/2008; 99(26):265002. · 7.37 Impact Factor -
Article: Twin-elliptical-crystal time- and space-resolved soft x-ray spectrometer
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ABSTRACT: Elliptical crystal spectrometers equipped with time-gated microchannel plate (MCP) detectors provide time-, space-, and spectrally resolved data. A common problem is that the number of time resolution elements is limited by the number of MCP frames. The number of frames that fit on a given MCP is limited by the image size and the alignment tolerance. At the Z facility these problems have been addressed with twin-elliptical-crystal spectrometers. Using two crystals and detectors doubles the number of frames available. This enables measurements with ∼ 350 ps time resolution while still recording data from an ∼ 4 ns wide time window. Alternatively, the twin crystal design allows simultaneous measurements with different crystals to investigate different spectral regimes.Review of Scientific Instruments 09/2006; 77(10):10F315-10F315-4. · 1.37 Impact Factor -
Article: Time- and space-resolved elliptical crystal spectrometers for high energy density physics research
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ABSTRACT: X-ray spectrometers used in high energy density plasma experiments must provide high time, space, and spectral resolution while overcoming the difficulties imposed by x-ray background, debris, and mechanical shocks. At the Z facility these problems are addressed using a suite of elliptical crystal spectrometers. The elliptical geometry isolates the detector from the line of sight with a slit placed at the elliptical focus, while the sensitivity enables locating the crystal 2–4 m from the plasma source. Space and time resolution are obtained by using an array of slits to project one dimensional plasma images onto the crystal and recording the spectrally dispersed images with a gated microchannel plate detector.Review of Scientific Instruments 10/2004; 75(10):3690-3692. · 1.37 Impact Factor -
Article: Hot dense capsule-implosion cores produced by Z-pinch dynamic Hohlraum radiation.
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ABSTRACT: Hot dense capsule implosions driven by Z-pinch x rays have been measured using a approximately 220 eV dynamic Hohlraum to implode 1.7-2.1 mm diameter gas-filled CH capsules. The capsules absorbed up to approximately 20 kJ of x rays. Argon tracer atom spectra were used to measure the T(e) approximately 1 keV electron temperature and the n(e) approximately 1-4 x 10(23) cm(-3) electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak emission values of T(e), n(e), and symmetry, indicating reasonable understanding of the Hohlraum and implosion physics.Physical Review Letters 03/2004; 92(8):085002. · 7.37 Impact Factor -
Article: X-ray imaging measurements of capsule implosions driven by a Z-pinch dynamic hohlraum.
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ABSTRACT: The radiation and shock generated by impact of an annular tungsten Z-pinch plasma on a 10-mm diam 5-mg/cc CH(2) foam are diagnosed with x-ray imaging and power measurements. The radiative shock was virtually unaffected by Z-pinch plasma instabilities. The 5-ns-duration approximately 135-eV radiation field imploded a 2.1-mm-diam CH capsule. The measured radiation temperature, shock radius, and capsule radius agreed well with computer simulations, indicating understanding of the main features of a Z-pinch dynamic-hohlraum-driven capsule implosion.Physical Review Letters 09/2002; 89(9):095004. · 7.37 Impact Factor