14 research outputs found
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LLNL Modeling Calculations in Support of the NMD EOS Program: FY01 3Q Report (U)
A program to examine equation-of-state (EOS) issues of interest to the National Missile Defense (NMD) program has been underway for a couple of years. There are current plans to conduct experiments at Sandia National Laboratory in Albuquerque. The initial experiments will be two-dimensional: a thin flyer will normally impact a target at two nominal velocities 6 km/s and 11 km/s. A witness plate is placed parallel to the target, separated from it by a 75 mm gap. Several channels of VISAR measure the particle velocity at different locations at the rear of the witness plate. A schematic of the experimental configuration is shown in Figure 1. At a kick-off meeting in March 2001, the initial computational task for all three laboratories (SNLA, LANL, and LLNL) was to calculate the witness plate particle velocity profiles produced by the two contemplated projectile sizes at both projectile velocities. This report documents these calculations as well as further calculations prompted by the initial results
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ALE advantage in hypervelocity impact calculations
The ALE3D code is used to model experiments relevant to hypervelocity impact lethality, carried out in the 4-5 km/s velocity range. The code is run in the Eulerian and ALE modes. Zoning in the calculations is refined beyond the level found in most lethality calculations, but still short of convergence. The level of zoning refinement that produces equivalent results in uniformly zoned Eulerian calculations and ALE ones utilizing specialized zoning, weighting and relaxation techniques is established. It takes 11 times fewer zones and about 60% as many cycles when ALE capabilities are used. Calculations are compared to experimental results
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High-power laser source evaluation
This document reports progress in these areas: EXPERIMENTAL RESULTS FROM NOVA: TAMPED XENON UNDERDENSE X-RAY EMITTERS; MODELING MULTI-KEV RADIATION PRODUCTION OF XENON-FILLED BERYLLIUM CANS; MAPPING A CALCULATION FROM LASNEX TO CALE; HOT X RAYS FROM SEEDED NIF CAPSULES; HOHLRAUM DEBRIS MEASUREMENTS AT NOVA; FOAM AND STRUCTURAL RESPONSE CALCULATIONS FOR NIF NEUTRON EXPOSURE SAMPLE CASE ASSEMBLY DESIGN; NON-IGNITION X-RAY SOURCE FLUENCE-AREA PRODUCTS FOR NUCLEAR EFFECTS TESTING ON NIF. Also appended are reprints of two papers. The first is on the subject of ``X-Ray Production in Laser-Heated Xe Gas Targets.`` The second is on ``Efficient Production and Applications of 2- to 10-keV X Rays by Laser-Heated Underdense Radiators.`
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LLNL Modeling Calculations in Support of the CLP Program: FY01 3Q Report
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Test Design Calculations II
In an earlier report, we presented results of modeling calculations for one simple geometry that represents an experiment potentially to be performed at Sandia National Laboratory, which is examining equation of state issues of interest to the National Missile Defense Program. In the earlier report, we showed snapshots of calculations with two different initial zone dimensions for Gruneisen EOS and LEOS. We also showed pressure profiles at various locations in a witness plate out of the way of direct projectile impact, but hit by shrapnel generated during impact. It was found that the pressure profiles exhibit strong dependence on location, zone size, and equation of state. In this report we examine the overall momentum impacted to the witness plate. This momentum shows negligible dependence on the equation of state and some dependence on zone size
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Wolter x-ray microscope calibration
A 22 x Wolter microscope was calibrated after several months of operation in the Lawrence Livermore National laboratory (LLNL) Inertial Confinement Fusion program. Placing a point x-ray source at the microscope focus, I recorded the image plane spectrum, as well as the direct spectrum, and from the ratio of these two spectra derived an accurate estimate of the microscope solid angle in the 1 to 4 keV range. The solid angle was also calculated using the microscope geometry and composition. Comparison of this calculated value with the solid angle that was actually measured suggests contamination of the microscope surface
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Test Problems for Reactive Flow HE Model in the ALE3D Code and Limited Sensitivity Study
We document quick running test problems for a reactive flow model of HE initiation incorporated into ALE3D. A quarter percent change in projectile velocity changes the outcome from detonation to HE burn that dies down. We study the sensitivity of calculated HE behavior to several parameters of practical interest where modeling HE initiation with ALE3D
Training and Research in Higher Education Institutions in Ukraine: Administrative and Financial Issues
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Development and Evaluation of First Wall Materials for the National Ignition Facility
Several low-Z refractory materials are evaluated for use as the NIF first wall in terms of their cost and ability to survive laser light, target emissions and debris, as well as be cleanable and not outgas excessively. Best performers contain B, C, or both, with B{sub 4}C being the best overall. It appears possible at this time that plasma-sprayed B{sub 4}C can be fabricated with low enough porosity and cost to be preferred to hot-pressed B{sub 4}C, the conservative choice