The Z Refurbishment Project was completed in September 2007. Prior to the shutdown of the Z facility in July 2006 to install the new hardware, it provided currents of {le} 20 MA to produce energetic, intense X-ray sources ({approx} 1.6 MJ, > 200 TW) for performing high energy density science experiments and to produce high magnetic fields and pressures for performing dynamic material property experiments. The refurbishment project doubled the stored energy within the existing tank structure and replaced older components with modern, conventional technology and systems that were designed to drive both short-pulse Z-pinch implosions and long-pulse dynamic material property experiments. The project goals were to increase the delivered current for additional performance capability, improve overall precision and pulse shape flexibility for better reproducibility and data quality, and provide the capacity to perform more shots. Experiments over the past year have been devoted to bringing the facility up to full operating capabilities and implementing a refurbished suite of diagnostics. In addition, we have enhanced our X-ray backlighting diagnostics through the addition of a two-frame capability to the Z-Beamlet system and the addition of a high power laser (Z-Petawatt). In this paper, we will summarize the changes made to the Z facility, highlight the new capabilities, and discuss the results of some of the early experiments.
Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic (MHD) simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.
Complementary gas-gun and electro-magnetic pulse tests conducted in Sandia's Dynamic Integrated Compression Experimental (DICE) Facility have, respectively, probed the behavior of electronic-grade Kovar samples under controlled impact and intermediate-strain-rate ICE (Isentropic Compression Experiment) loading. In all tests, velocity interferometer (VISAR) diagnostics provided time-resolved measurements of sample response for conditions involving one-dimensional (i:e:, uniaxial strain) compression and release. Wave-profile data from the gas-gun impact experiments have been analyzed to assess the Hugoniot Elastic Limit (HEL), Hugoniot equation of state, spall strength, and high-pressure yield strength of shocked Kovar. The ICE wave-profile data have been interpreted to determine the locus of isentropic stress-strain states generated in Kovar for deformation rates substantially lower than those associated with a shock process. The impact and ICE results have been compared to examine the influence of loading rate on high-pressure strength.