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in creator/contributor: "Lorenz, K. T."  
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Formulation and Mechanical Properties of LLM-105 PBXs

Description: Eight different polymer binders were formulated with bimodal distributions of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) in 5/95 weight ratio of polymer to explosive at the 25 gram level. The polymers evaluated included: Kel-F 800, Viton A, Oxy 461, Cytop A, Hyflon AD 60, Hytemp 5545, Technoflon PFR 91 and Technoflon P 459. LLM-105 had an average particle size of 35.6 {+-} 0.6 {micro}m. This material was ground in a ball mill for 24 h to achieve a particle size of 0.72 {+-} 0.02 {micro}m… more
Date: April 3, 2008
Creator: Hoffman, D. M.; Lorenz, K. T.; Cunningham, B. & Gagliardi, F.
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Partner: UNT Libraries Government Documents Department
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Materials Response Under Extreme Conditions

Description: Solid state experiments at extreme pressures, 10-100 GPa (0.1-1 Mbar) and strain rates (10{sup 6}-10{sup 8} s{sup -1}) are being developed on high-energy laser facilities. The goal is an experimental capability to test constitutive models for high-pressure, solid-state strength for a variety of materials. Relevant constitutive models are discussed, and our progress in developing a quasi-isentropic, ramped-pressure, shockless drive is given. Designs to test the constitutive models with experimen… more
Date: October 6, 2005
Creator: Remington, B. A.; Lorenz, K. T.; Pollaine, S. & McNaney, J. M.
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Partner: UNT Libraries Government Documents Department
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Deflagration Rate Measurements of Three Insensitive High Explosives: LLM-105, TATB, and DAAF

Description: The pressure dependent deflagration rates of LLM-105, DAAF and TATB based formulations were measured in the LLNL high pressure strand burner. The role of binder amount, explosive type, and thermal damage and their effects on the deflagration rate will be discussed. One DAAF formulation, two different formulations of LLM-105, and four formulations of TATB were studied; results indicate that binder amount and type play a minor role in the deflagration behavior. This is in sharp contrast to the HM… more
Date: March 8, 2010
Creator: Glascoe, E A; Maienschein, J L; Lorenz, K T; Tan, N & Koerner, J G
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Partner: UNT Libraries Government Documents Department
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High pressure, quasi-isentropic compression experiments on the Omega laser

Description: The high energy density of pulsed lasers can be used to generate shockless loading in solids to high pressures and compressions but low temperatures. We have used the Omega laser to extend the capabilities of this technique to multi-Mbar pressures and compressions approaching a factor of 2 in aluminum foils. The energy from a 3.7 ns laser pulse is used to drive a strong shock through a 200 {micro}m polystyrene disc. The disc material unloads from a high-pressure state and expands across a 300 {… more
Date: May 26, 2006
Creator: Lorenz, K. T.; Edwards, M. J.; Jankowski, Alan Frederic; Pollaine, S. M.; Smith, R. F. & Remington, B. A.
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Partner: UNT Libraries Government Documents Department
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Aluminum Rayleigh Taylor Strength Measurements and Calculations

Description: A traditional approach to the study of material strength has been revitalized at the Russian Federal Nuclear Center (VNIIEF). Rayleigh Taylor strength experiments have long been utilized to measure the material response of metals at high pressure and strain rates. A modulated (sinusoidal or sawtooth perturbation) surface is shocklessly (quasi-isentropically) accelerated by a high explosive (HE) driver, and radiography is used to measure the perturbation amplitude as a function of time. The Alum… more
Date: January 10, 2007
Creator: Lindquist, M. J.; Cavallo, R. M.; Lorenz, K. T.; Pollaine, S. M.; Remington, B. A. & Raevsky, V. A.
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Partner: UNT Libraries Government Documents Department
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Graded-density Reservoirs for Accessing High Pressure Low Temperature Material States

Description: In recently developed laser-driven shockless compression experiments an ablatively driven shock in a primary target is transformed into a ramp compression wave in a secondary target via unloading followed by stagnation across an intermediate vacuum gap. Current limitations on the achievable peak pressures are limited by the ability of shaping the temporal profile of the ramp compression pulse. We report on new techniques using graded density reservoirs for shaping the loading profile and extend… more
Date: April 19, 2006
Creator: Smith, R.; Lorenz, K. T.; Ho, D.; Remington, B.; Hamza, A.; Rogers, J. et al.
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Partner: UNT Libraries Government Documents Department
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Accessing Ultra-High Pressure, Quasi-Isentropic States of Matter

Description: A new approach to the study of material strength of metals at extreme pressures has been developed on the Omega laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample nearly isentropically. The peak pressure on the sample, inferred from VISAR measurements of velocit… more
Date: November 12, 2004
Creator: Lorenz, K. T.; Edwards, M. J.; Glendinning, S. G.; Ho, D. D.; Jankowski, Alan Frederic; McNaney, J. et al.
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Partner: UNT Libraries Government Documents Department
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Comprehensive Characterization of Voids and Microstructure in TATB-based Explosives from 10 nm to 1 cm: Effects of Temperature Cycling and Compressive Creep

Description: This paper outlines the characterization of voids and Microstructure in TATB-based Explosives over several orders of magnitude, from sizes on the order of 10 nm to about 1 cm. This is accomplished using ultra small angle x-ray scattering to investigate voids from a few nm to a few microns, ultra small angle neutron scattering for voids from 100 nm to 10 microns, and x-ray computed microtomography to investigate microstructure from a few microns to a few centimeters. The void distributions of LX… more
Date: February 26, 2010
Creator: Willey, T. M.; Lauderbach, L.; Gagliardi, F.; Cunningham, B.; Lorenz, K. T.; Lee, J. I. et al.
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Partner: UNT Libraries Government Documents Department
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EXPERIMENTAL TESTS OF VANADIUM STRENGTH MODELS AT HIGH PRESSURES AND STRAIN RATES

Description: Experimental results showing significant reductions from classical in the Rayleigh-Taylor (RT) instability growth rate due to high pressure material strength or effective lattice viscosity in metal foils are presented. On the Omega Laser in the Laboratory for Laser Energetics, University of Rochester, target samples of polycrystalline vanadium are compressed and accelerated quasi-isentropically at {approx}1 Mbar pressures, while maintaining the samples in the solid-state. Comparison of the resu… more
Date: March 2, 2010
Creator: Park, H.; Barton, N. R.; Becker, R. C.; Bernier, J. V.; Cavallo, R. M.; Lorenz, K. T. et al.
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Partner: UNT Libraries Government Documents Department
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Strong stabilization of the Rayleigh-Taylor instability by material strength at Mbar pressures

Description: Experimental results showing significant reductions from classical in the Rayleigh-Taylor (RT) instability growth rate due to high pressure effective lattice viscosity are presented. Using a laser created ramped drive, vanadium samples are compressed and accelerated quasi-isentropically at {approx}1 Mbar pressures, while maintaining the sample in the solid-state. Comparisons with simulations and theory indicate that the high pressure, high strain rate conditions trigger a phonon drag mechanism,… more
Date: November 19, 2009
Creator: Park, H. S.; Lorenz, K. T.; Cavallo, R. M.; Pollaine, S. M.; Prisbrey, S. T.; Rudd, R. E. et al.
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Partner: UNT Libraries Government Documents Department
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Materials Science at the Extremes of Pressure and Strain Rate

Description: Solid state experiments at very high pressures and strain rates are possible on high power laser facilities, albeit over brief intervals of time and spatial small scales. A new shockless drive has been developed on the Omega laser. VISAR measurements establish the high strain rates, 10{sup 7}-10{sup 8} s{sup -1}. Solid-state strength is inferred using the Rayleigh-Taylor instability as a ''diagnostic''. Temperature and compression in polycrystalline samples can be deduced from EXAFS measurement… more
Date: August 20, 2003
Creator: Remington, B. A.; Cavallo, R. M.; Edwards, M. J.; Lasinski, B. F.; Lorenz, K. T.; Lorenzana, H. E. et al.
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Partner: UNT Libraries Government Documents Department
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Laser Driven High Pressure, High Strain-Rate Materials Experiments

Description: Laser-based experiments are being developed to study the response of solids under high pressure loading. Diagnostic techniques that have been applied include dynamic x-ray diffraction, VISAR wave profile measurements, and post-shock recovery and analysis. These techniques are presented with some results from shocked Si, Al, and Cu experiments.
Date: June 29, 2001
Creator: Kalantar, D. H.; Allen, A. M.; Gregori, F.; Kad, B.; Kumar, M.; Lorenz, K. T. et al.
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Partner: UNT Libraries Government Documents Department
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Accessing High Pressure States Relevant to Core Conditions in the Giant Planets

Description: We have designed an experimental technique to use on the National Ignition Facility (NIF) laser to achieve very high pressure (P{sub max} > 10 Mbar = 1000 GPa), dense states of matter at moderate temperatures (kT < 0.5 eV = 6000 K), relevant to the core conditions of the giant planets. A discussion of the conditions in the interiors of the giant planets is given, and an experimental design that can approach those conditions is described.
Date: April 15, 2004
Creator: Remington, B. A.; Cavallo, R. M.; Edwards, M. J.; Ho, D. D.; Lorenz, K. T.; Lorenzana, H. E. et al.
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Partner: UNT Libraries Government Documents Department
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Multiple Film Plane Diagnostic for Shocked Lattice Measurements

Description: Laser-based shock experiments have been conducted in thin Si and Cu crystals at pressures above the Hugoniot Elastic Limit (HEL). In these experiments, static film and x-ray streak cameras recorded x-rays diffracted from lattice planes both parallel and perpendicular to the shock direction. This data showed uniaxial compression of Si (100) along the shock direction and 3-D compression of Cu (100). In the case of the Si diffraction, there was a multiple wave structure observed, which may be due … more
Date: July 2, 2002
Creator: Kalantar, D. H.; Bringa, E.; Caturla, M.; Colvin, J.; Lorenz, K. T.; Kumar, M. et al.
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Partner: UNT Libraries Government Documents Department
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Materials Science under Extreme Conditions of Pressure and Strain Rate

Description: Solid state dynamics experiments at very high pressures (P >> 10 GPa) and strain rates ({var_epsilon} >> 10{sup 5} s{sup -1}) have been demonstrated on high energy laser facilities, albeit over brief intervals of time and small spatial scales. We have developed two methods for driving samples to high pressures (10-100 GPa) at high strain rate (10{sup 6}-10{sup 8} s{sup -1}) in the solid state. One method uses a shockless compression technique, and the other uses multiple staged shoc… more
Date: March 27, 2003
Creator: Remington, B. A.; Bazan, G.; Bringa, E.; Caturla, M.; Edwards, M. J.; Glendinning, S. G. et al.
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Partner: UNT Libraries Government Documents Department
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