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A series of pulsed power driven recent Kr gas-puff experiments on the Sandia National Laboratories Z machine have produced intense X-rays in the multi-keV photon energy range. Krypton spectra from Z pinch implosions can be used to analyze the presence and dynamics of the emitting regions, which could dominate the Kr K- and L-shell yields. This theoretical investigation of highly charged high atomic...
The Differential Absorption Hard X-ray (DAHX) spectrometer has been developed to diagnose photon energies above 80 keV and provides a time-resolved measurement of the x-ray spectrum from the plasma driven by Z. The DAHX spectrometer is a revitalization of the Hard X-Ray Spectrometer (HXRS) fielded on Z prior to refurbishment1. DAHX consists of an array of seven collimated silicon PIN diodes with varying...
A two-dimensional radiation MHD model that includes a self-consistent calculation for non-local thermodynamic equilibrium kinetics and ray-trace radiation transport1 is employed to simulate 65 mm diameter stainless steel double wire array Z machine experiments of 5.0 mg - shot Z1859 and 2.5 mg - shot Z1860 as well as 8 cm diameter, 2.5 mg, argon gas-puff experiments, shots Z2259 - Z2261. Temporal...
We present a study of the formation of bow shocks in radiatively cooled plasma flows. This work uses the XP generator (260kA, 145ns) at Cornell University to drive an inverse wire array. This generates a quasi-uniform, large scale hydrodynamic flow accelerated by Lorentz forces to Ma > 1. This flow impacts a stationary object placed in its path, forming a well-defined Mach cone. Collinear interferogram...
Wire array z-pinches on the Z generator are bright sources of radiation from 200eV to 9keV. Typically, wire materials are varied to provide emission in a specific spectral band, and the array setup is varied in order to provide appropriate energy per ion to heat the stagnated plasma to an electron temperature conducive to efficient emission within that band. Here we discuss a series of experiments...
We have reestablished gas puff z-pinch capability on Sandia's 20 MA Z machine, including a Sandia-operated driver system and an imaging interferometer to characterize nozzle mass flow [1]. Initial experiments have focused on developing a 3 keV Ar K-shell x-ray source. We have pursued a design-driven approach to planning these experiments, utilizing numerical simulation to predict Ar K-shell yield...
The refurbishment of Sandia's Z generator, completed in late 2007, represents a significant enhancement in its capabilities. In addition to increased operational efficiency and reliability, up to twice the previous energy can be stored in its present capacitors, allowing for greater load current and coupled energy1. Despite losses occurring near the load, enhancements of current of ∼ 15% and load...
A number of shots employing concentric gas puffs of Ar and Kr on the Sandia National Laboratories ZR accelerator are being planned; with the goal of optimizing K-shell yield. Experimental data from these implosions can provide a wealth of information about the pinch dynamics and ionization history of the plasma. Theoretical simulations using accurate atomic and hydrodynamics models will provide synthetic...
Large diameter multi-shell gas puffs imploded on the refurbished Z generator will be able to produce high-intensity K-shell radiation. Gas puffs have previously been fielded on a number of generators, including Z prior to the refurbishment. In anticipation of gas puff loads soon to be commissioned on refurbished Z we present preliminary 3-dimensional MHD modeling of the implosion and stagnation of...
Advances in diagnostics at the refurbished Z facility at Sandia National Laboratories (SNL) now allow spatially and temporally resolved spectra to be obtained, with improved signal-to-noise ratios. Z-pinch simulation models have also improved, due both to substantial advances in the understanding of the underlying physics, and to the development of more detailed and accurate atomic databases. We will...
Argon z-pinch experiments are to be performed on the refurbished Z machine at Sandia National Laboratories with a new 8 cm diameter double-annulus gas puff nozzle constructed by AASC. The gas exits the nozzle from an outer and inner annulus and a central jet. The amount of gas present in each region can be varied. Here we employ a two-dimensional radiation MHD model to theoretically investigate stability...
Large diameter nested wire array z-pinches imploded on the Z-generator at Sandia National Laboratories have been used to generate high intensity K-shell radiation. Previous experiments have used different materials between the inner and outer array to allow radiation emitted during the implosion and stagnation to provide some insight into the structure of the imploding plasma and the way in which...
Advances in diagnostic techniques at the Sandia Z-facility have facilitated the production of very detailed spectral data. In particular, data from the copper nested wire-array shot Z1975 potentially provides a wealth of information about the implosion dynamics and ionization history of the pinch. This shot was simulated with the NRL 1-D DZAPP non-LTE radiation-hydrodynamics model, and the resulting...
Magnetically driven implosions of wire array and gas puff loads on the 20 MA Z and 8 MA Saturn pulsed power drivers provide extremely intense x-ray sources. Each facility fields multi-frame, multi-color, x-ray pinhole cameras in order to assess source uniformity and study implosion dynamics. The instruments feature cameras filtered for >1 keV photons, as well as pinhole cameras in which <1...
Pulsed power is a key driver for high energy density (HED) science. The Z-Machine is the world's largest pulsed power driver, and as such is one of the foremost platforms for HED science. The double post-hole convolute current adder is a critical element in low impedance, multi-module pulsed power device design. Post-refurbishment, the current loss in the convolute has reached as high as 5 MA (20%...
Large diameter (50-70 mm) wire array z pinches are fielded on the refurbished Z machine to generate 1-10 keV K-shell x-ray radiation. Imploding with velocities approaching 100 cm/μs, these loads create large dL/dt which generates a high voltage, stresses the convolute, and leads to current loss. High velocities are required to reach the few-keV electron temperatures required to strip moderate-atomic-number...
Summary form only given. The development of shocks in plasma flows occurs in a wide range of environments, including fusion schemes and astrophysical objects. In wire array experiments, the plasma accelerated from the wire via the Lorentz force rapidly exceeds both the local sound and Alfven speeds, providing an interesting source for shock studies. Recently, the plasma flow in a 1 MA wire array z-pinch...
Intriguing time-gated, radially resolved L-shell line emission profiles have been observed from recent Cu/Ni wire array implosions on Sandia's Z facility. The well resolved measurements exhibit lineshapes that appear as hollow, asymmetric ovals whose variations in the intensity, spatial, and (Doppler-shifted) wavelength dimensions yield information on plasma densities, temperatures, gradients, dimensions,...
Large diameter nested wire array z-pinches imploded on the Z-generator at Sandia National Laboratories have been used extensively to generate high intensity K-shell radiation. Large initial radii are required to obtain the high implosion velocities needed to efficiently radiate in the K-shell. This necessitates low wire numbers and large inter-wire gaps which introduce large azimuthal non-uniformities...
We will discuss experiments on the Z generator using large diameter stainless steel wire arrays to produce K-shell emission (hv~6.7keV). Large array diameters and fast implosion times are needed to obtain high velocities and high temperatures in order to excite Fe K-shell emission.Since the refurbishment of the Z generator, nested stainless steel wire arrays have been fielded at 65mm, 70mm and 75...
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