Christine Anne Coverdale

Investigation of radial wire arrays for inertial confinement fusion and radiation effects science.

Radial wire arrays provide an alternative x-ray source for Z-pinch driven Inertial Confinement Fusion. These arrays, where wires are positioned radially outwards from a central cathode to a concentric anode, have the potential to drive a more compact ICF hohlraum. A number of experiments were performed on the 7MA Saturn Generator. These experiments studied a number of potential risks in scaling radial wire arrays up from the 1MA level, where they have been shown to provide similar x-ray outputs to larger diameter cylindrical arrays, to the higher current levels required for ICF. Data indicates that at 7MA radial arrays can obtain higher power densities than cylindrical wire arrays, so may be of use for x-ray driven ICF on future facilities. Even at the 7MA level, data using Saturns short pulse mode indicates that a radial array should be able to drive a compact hohlraum to temperatures {approx}92eV, which may be of interest for opacity experiments. These arrays are also shown to have applications to jet production for laboratory astrophysics. MHD simulations require additional physics to match the observed behavior.

Spectroscopic Modeling and Comparison of Radiation from X-Pinches and Wire Arrays Produced on the 1 MA Pulsed Power Generator at UNR

Summary form only given. X-ray spectra and images from Al (with 5% of Mg and some with 5% of NaF dopants) and Cu (pure and with 4% of Ni) wire arrays and X-pinches were accumulated in experiments on the 1 MA pulsed power generator at UNR. In particular, axially and radially resolved K-shell X-ray spectra of Al, Mg, and Na and L-shell X-ray spectra of Cu and Ni were recorded by a KAP crystal (in a spectral region from 6 to 15 Aring) through different slits from 50 mum to 3 mm. In addition, spatially integrated harder X-ray spectra were monitored by a LiF crystal. Non-LTE kinetic models of Al, Mg, and Na, and of Cu and Ni provided spatially resolved electron temperatures and densities for experiments with Al and Cu loads, respectively. Advantages of using alloys and dopants with small concentrations for spectroscopic plasma diagnostics will be presented. Dependence of the plasmas spatial structures, temperatures, and densities from wire material and load configurations, sizes, and masses will be discussed

Simulation of Nested Stainless Steel Wire Arrays on Z with a Detailed Radiation-Hydrodynamics Model

Summary form only given. Recent experiments on the Z accelerator employing nested stainless steel wire arrays have produced K-shell X-ray yields in excess of 50 kJ in the range 5.5 to 8.0 keV. Stainless steel (Z=24-28) can barely be ionized to the K-shell on Z, and the spectra are thus sensitive to the implosion history. We have employed a detailed configuration non-LTE radiation hydrodynamics model to simulate the implosion dynamics of wire array configurations with diameters of 4.5 to 8.0 centimeters. Good overall agreement with total and K-shell experimental yields was obtained for the cases studied. In addition, the K-shell spectra for shots Z-578 and Z-581 closely replicated the observed spectra. The line shapes of the He-lines were reproduced using a more detailed multifrequency radiation transport model. The most prominent K-shell line is actually a complex of the self-reversed Fe He-line, the Fe inter-combination line and two Cr He-like lines. Detailed spectra, energetics and pinch histories will be shown