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in publisher: "Lawrence Livermore National Laboratory"  
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Estimate of external background radiation interference on a tomography scanner

Description: We have estimated interference from external background radiation for a computed tomography (CT) scanner. Our intention is to estimate the interference that would be expected for the high-resolution SkyScan 1072 desk-top x-ray microtomography system. The SkyScan system uses a Microfocus x-ray source capable of a 10-{micro}m focal spot at a maximum current of 0.1 mA and a maximum energy of 130 kVp. All predictions made in this report assume using the x-ray source at the smallest spot size, maxim… more
Date: July 21, 2000
Creator: Roberson, G P & Logan, C M
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Modeling of an inductive adder kicker pulser for DARHT-II

Description: An all solid-state kicker pulser for a high current induction accelerator (the Dual-Axis Radiographic Hydrodynamic Test facility DARHT-2) has been designed and fabricated. This kicker pulser uses multiple solid state modulators stacked in an inductive-adder configuration. Each modulator is comprised of multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) which quickly switch the energy storage capacitors across a magnetic induction core. Metglas is used as the core material to … more
Date: September 25, 2000
Creator: Wang, L.; Caporaso, G. J. & Cook, E. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Structure of Cool Flame Fronts of Pentane, Iso-Pentane and Their Mixture

Description: An experimental study of the combustion of two isomers of pentane, n-pentane and iso-pentane, in laminar cool flames has been carried out. Three flames were studied, one with n-pentane, the second with iso-pentane, and the third with an equimolar mixture of the two isomers. Particular attention has been given to the low temperature region ahead of the hot region of the flame and the cool flame chemistry occurring there. A unique experimental facility has been used to provide access to this cool… more
Date: January 11, 2000
Creator: Mansurov, Z A; Mironenko, A A; Bodykov, D U; Rakhimetkaliev, K N & Westbrook, C K
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

NIF optics

Description: One of the major highlights of the technology development for the National Ignition Facility (NIF) is the optics. NIF will be the largest laser ever built, requiring 7500 large optics (over one foot across) and more than 30,000 small optics. The design, manufacture, and assembly of these important pieces have called for innovative ways to make optics of higher quality than ever before, and to do so at unprecedented speeds. The most obvious role of NIF optics is to steer the 192 laser beams thro… more
Date: August 30, 2000
Creator: Parham, T
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Use of Imperfect Calibration for Seismic Location

Description: Efforts to more effectively monitor nuclear explosions include the calibration of travel times along specific paths. Benchmark events are used to improve travel-time prediction by (1) improving models, (2) determining travel times empirically, or (3) using a hybrid approach. Even velocity models that are determined using geophysical analogy (i.e. models determined without the direct use of calibration data) require validation with calibration events. Ideally, the locations and origin times of c… more
Date: July 12, 2000
Creator: Myers, S C & Schultz, C A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

NLC photon collider option progress and plans

Description: The idea of producing beams of high energy photons by Compton backscattering of laser photons was proposed over 20 years ago. At the time, producing the required laser pulses was not feasible. However, recent advances in high average power, diode pumped lasers appear to have solved this problem. The US Collaboration is now turning its attention to the engineering requirement of mating the laser and optics components with the accelerator structures in the confined space of the a colliding beam i… more
Date: August 31, 2000
Creator: Gronberg, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Material transfer system in support of the plutonium immobilization program

Description: The Plutonium Immobilization Program requires development of the process and plant prototypic equipment to immobilize surplus plutonium in ceramic for long-term storage. Because of the hazardous nature of plutonium, it was necessary to develop a remotely operable materials transfer system which can function within the confines of a glovebox. In support of this work at LLNL, such a material transfer system (MTS) was developed. This paper presents both the mechanical and controls parts making up … more
Date: December 20, 2000
Creator: Pak, D
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Graph based multilevel algorithms for preconditioning finite element problems

Description: This paper discusses: (1) A general block-factorization (matrix) form of multilevel preconditioners; algebraic methods; (2) Selecting parameters based on the matrix topology; graph based algorithms; (3) Examples of coarsening; (4) Numerical experiments.
Date: March 24, 2000
Creator: Vassilevski, P S
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Paradyn a parallel nonlinear, explicit, three-dimensional finite-element code for solid and structural mechanics user manual

Description: ParaDyn is a parallel version of the DYNA3D computer program, a three-dimensional explicit finite-element program for analyzing the dynamic response of solids and structures. The ParaDyn program has been used as a production tool for over three years for analyzing problems which range in size from a few tens of thousands of elements to between one-million and ten-million elements. ParaDyn runs on parallel computers provided by the Department of Energy Accelerated Strategic Computing Initiative … more
Date: June 1, 2000
Creator: Hoover, C G; DeGroot, A J & Sherwood, R J
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Synthesis and Characterization of Porous Hydroxyapatite and Hydroxyapatite Coatings

Description: A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using water-soluble compounds and then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously reported. R… more
Date: October 25, 2000
Creator: Nieh, T. G.; Choi, B. W. & Jankowski, Alan Frederic
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Relative x-ray backlighter intensity comparison of ti and ti/sc combination foils driven in double-sided and single-sided laser configuration

Description: Use of multiple backlighter foils and/or double-sided laser interaction geometry with backlit imaging can result in improved backlighter efficiency. An experimental comparison of backlighter intensity for Ti foils and Ti/Sc combination foils in both the one-sided and double-sided laser-interaction configuration is presented. Spectrally-integrated framing camera images show intensity contributions of front and rear backlighter surfaces for both foil types. Analysis of time-resolved x-ray spectra… more
Date: June 5, 2000
Creator: Bullock, A. B.; Landen, O. L. & Bradley, D. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Relative stability of silicon self-interstitial defects

Description: {l_brace}311{r_brace} defects and dislocation loops are formed after ion-implantation and annealing of a silicon wafer. Recent Transmission Electron Microscopy studies by Li and Jones have shown that sub-threshold dislocation loops nucleate from {l_brace}311{r_brace} defects. In our study, the conjugate gradient method with the Stillinger Weber potential is used to relax different configurations such as {l_brace}311{r_brace} defects with a maximum of five chains and perfect dislocation loops. F… more
Date: April 11, 2000
Creator: Subramanian, G; Jones, K S; Law, M E; Caturla, M J; Theiss, S & Diaz de la Rubia, T
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Micromechanical characterization tools for highly-filled polymers

Description: We are attempting to characterize and model the micromechanical response of highly-filled polymers. In this class of materials, the continuous plastic binder used to bond the highly-filled material dominates the observed viscoelastic response. As a result, realistic lifetime analysis of these materials will require a thorough understanding of the contribution of the plastic binder. Laboratory applications of these materials include plastic bonded explosives, propellants, a variety of specialize… more
Date: February 16, 2000
Creator: Groves, S; DeTeresa, S; Cunningham, B; Ciarlo, D; Allen, D; Clayton, K et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Institute for scientific computing research;fiscal year 1999 annual report

Description: Large-scale scientific computation, and all of the disciplines that support it and help to validate it, have been placed at the focus of Lawrence Livermore National Laboratory by the Accelerated Strategic Computing Initiative (ASCI). The Laboratory operates the computer with the highest peak performance in the world and has undertaken some of the largest and most compute-intensive simulations ever performed. Computers at the architectural extremes, however, are notoriously difficult to use effi… more
Date: March 28, 2000
Creator: Keyes, D
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Wireless link design using a patch antenna

Description: A wireless link was designed using a patch antenna. In the process, several different models were tested. Testing proved a patch antenna was a viable solution for building a wireless link within the design specifications. Also, this experimentation provided a basis for future patch antenna design.
Date: August 11, 2000
Creator: Hall, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Using pseudo transient continuation and the finite element method to solve the nonlinear Poisson-Boltzmann equation

Description: The nonlinear Poisson-Boltzmann (PB) equation is solved using Pseudo Transient Continuation. The PB solver is constructed by modifying the nonlinear diffusion module of a 3D, massively parallel, unstructured-grid, finite element, radiation-hydrodynamics code. The solver also computes the electrostatic energy and evaluates the force on a user-specified contour. Either Dirichlet or mixed boundary conditions are allowed. The latter specifies surface charges, approximates far-field conditions, or l… more
Date: December 27, 2000
Creator: Shestakov, A I; Milovich, J L & Noy, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Internal Voltage in a Conducting Closed Hollow Cylinder With an Attached End Plate Subjected to a Direct Lightning Strike

Description: The interior voltage of a large metal can with thick walls struck directly by lightning was estimated using diffusion theory, aperture slot voltage theory, and experimental data. The hollow cylinder is closed at both ends. One end has a cap that is welded to the cylinder wall making a continuous electrical interface. The other end consists of a circular plate that is pressed into the cylinder wall and held under pressure with a threaded ring. From our experience with coupling measurements, this… more
Date: June 1, 2000
Creator: Ong, M. M. & Anderson, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

HCCI engine control by thermal management

Description: This work investigates a control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), that has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficien… more
Date: May 11, 2000
Creator: Martinez-Frias, J; Aceves, S M; Flowers, D; Smith, J R & Dibble, R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

An Examination of the Effects of Be Grain Size

Description: During the WBS4 review almost a year ago in January, and in more recent discussions of needed capsule characterization, I was struck by three pieces of information related to machined Be capsules: (1) that the speed of sound (and perhaps other properties) in Be grains is markedly different in orthogonal directions, (2) that the grain size in the best refined bulk Be samples is 10 to 15 {micro}m, and that these grains in the best case are randomly oriented, and (3) that we are concerned about ca… more
Date: November 21, 2000
Creator: Cook, R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

ITER CS Model Coil and CS Insert Test Results

Description: The Inner and Outer modules of the Central Solenoid Model Coil (CSMC) were built by US and Japanese home teams in collaboration with European and Russian teams to demonstrate the feasibility of a superconducting Central Solenoid for ITER and other large tokamak reactors. The CSMC mass is about 120 t, OD is about 3.6 m and the stored energy is 640 MJ at 46 kA and peak field of 13 T. Testing of the CSMC and the CS Insert took place at Japan Atomic Energy Research Institute (JAERI) from mid March … more
Date: September 7, 2000
Creator: Martovetsky, N.; Michael, P.; Minervini, J.; Radovinsky, A.; Takayasu, M.; Thome, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Spheromak formation studies in SSPX

Description: We present results from the Sustained Spheromak Physics Experiment (SSPX) at LLNL, which has been built to study energy confinement in spheromak plasmas sustained for up to 2 ms by coaxial DC helicity injection. Peak toroidal currents as high as 600kA have been obtained in the 1m dia. (0.23m minor radius) device using injection currents between 200-400kA; these currents generate edge poloidal fields in the range of 0.2-0.4T. The internal field and current profiles are inferred from edge field m… more
Date: September 29, 2000
Creator: Hill, D. N.; Bulmer, R. H.; Cohen, B. L.; Hooper, E. B.; LoDestro, L. L.; Mattor, N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Defect diffusion during annealing of low-energy ion-implanted silicon

Description: We present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7x7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of … more
Date: March 8, 2000
Creator: Bedrossian, P J; Caturla, M-J & Diaz de la Rubia, T
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Terascale simulations for heavy ion inertial fusion energy

Description: The intense ion beams in a heavy ion Inertial Fusion Energy (IFE) driver and fusion chamber are non-neutral plasmas whose dynamics are largely dominated by space charge. We propose to develop a ''source-to-target'' Heavy Ion Fusion (HIF) beam simulation capability: a description of the kinetic behavior of this complex, nonlinear system which is both integrated and detailed. We will apply this new capability to further our understanding of key scientific issues in the physics of ion beams for IF… more
Date: June 8, 2000
Creator: Friedman, A.; Cohen, R. H.; Grote, D. P.; Sharp, W. M.; Celata, C. M.; Lee, E. P. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Tearing and MHD Instability During Gun Injection into a Spheromak

Description: Linear stability analysis of a two-cylinder approximation to gun injection--one cylinder to represent the confined spheromak and another to represent the gun--is shown to yield equilibria in which tearing modes exist simultaneously at the magnetic axis and at the geometric (gun) axis, as might be required to sustain helicity injection. These equilibria are MHD stable at the two axes but may have localized MHD instability at an interior minimum in the q profile. The theory predicts two tearing t… more
Date: May 11, 2000
Creator: Fowler, T K
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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