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Ab initio calculations on collisions of low energy electrons with polyatomic molecules

Description: The Kohn variational method is one of simplest, and oldest, techniques for performing scattering calculations. Nevertheless, a number of formal problems, as well as practical difficulties associated with the computation of certain required matrix elements, delayed its application to electron--molecule scattering problems for many years. This paper will describe the recent theoretical and computational developments that have made the complex'' Kohn variational method a practical tool for carryin… more
Date: August 1, 1991
Creator: Rescigno, T. N.
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Partner: UNT Libraries Government Documents Department
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A cryogenic system design for the international thermonuclear experimental reactor (ITER)

Description: A conceptual design for ITER was completed last year. The author developed a suitable cryogenic system for ITER as part of this conceptual design effort. An overview of the design is reported. Emphasis is on the fact that cryogenics is a mature science, and a system supporting ITER needs can be made from time-proven components without loss of efficiency or reliability. Because of the large size of the ITER cryogenic system, large numbers of compressors and expanders must be used. Very high reli… more
Date: September 25, 1991
Creator: Slack, D.S.
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Partner: UNT Libraries Government Documents Department
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Future aircraft and potential effects on stratospheric ozone and climate

Description: The purpose of this study is to extend the recent research examining the global environmental effects from potential fleets of subsonic and supersonic commercial aircraft. Initial studies with LLNL models of global atmospheric chemical, radiative, and transport processes have indicated that substantial decreases in stratospheric ozone concentrations could result from emissions of NO{sub x} from aircraft flying in the stratosphere, depending on fleet size and magnitude of the engine emissions. T… more
Date: October 1, 1991
Creator: Kinnison, D.E. & Wuebbles, D.J.
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Partner: UNT Libraries Government Documents Department
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Slit-mounted LED fiducial system for rotating mirror streak cameras

Description: We have developed a fiducial system for rotating mirror streak cameras that utilizes light emitting diodes mounted at the slit position of the camera. The diodes are driven to the required high brightness by a unique pulse power circuit designed to provide high voltage, high current pulses 18 nanoseconds in length at a frequency of up to 2.5 megahertz. The availability of super bright light emitting diodes with a wavelength of 630 to 640 nanometers allows us to record fiducial pulses, at streak… more
Date: January 1, 1991
Creator: Shaw, L.L.; Muelder, S.A. & Rivera, A.T.
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Partner: UNT Libraries Government Documents Department
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Visual tools and languages: Directions for the '90s

Description: We identify and discuss three domains where we believe that innovative application of visual programming languages is likely to make a significant impact in the near term: concurrent computing, computer-based assistance for people with disabilities, and the multimedia/multimodal environments of tomorrow in which it will be possible to hear and physically interact with information as well as see it. 33 refs., 3 figs.
Date: January 1, 1991
Creator: Glinert, E.P. (Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Computer Science); Blattner, M.M. (Lawrence Livermore National Lab., CA (United States)) & Frerking, C.J. (California Univ., Davis, CA (United States))
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Partner: UNT Libraries Government Documents Department
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A sendmail. cf scheme for a large network

Description: Like most large networked sites our users depend heavily on the electronic mail system for both internal and off-site communications. Unfortunately the sendmail.cf file, which is used to control the behavior of the sendmail program, is somewhat cryptic and difficult to decipher for the neophyte. So, on one hand you have a highly visible, frequently used utility, and on the other hand a not-so-easily acquired system administration forte. Here is the sendmail topology of our site, what premises w… more
Date: August 14, 1991
Creator: Darmohray, T.M.
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Partner: UNT Libraries Government Documents Department
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Painter Street Overcrossing: Linear-elastic finite element dynamic analysis

Description: Painter Street Overcrossing is a two span continuous box girder bridge Highway 101 near Rio Del, California. It has been heavily instrumented with strong motion accelerometers by the California Department of Mines and Geology Strong Motion Instrumentation Program. On 11/21/86, the response of the bridge to a magnitude 5.1 earthquake (epicentral distance 32 km) was measured. This report considers the data generated at stations six, seven, and eight, during this earthquake. Station six recorded t… more
Date: August 1, 1991
Creator: Salveson, M.W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Excited state absorption measurements of Sm sup 2+ in CaF sub 2 , SrF sub 2 , and SrCl sub 2

Description: We measured the pump-probe spectrum of the Sm{sup 2+} ion in three materials: CaF{sub 2}, SrF{sub 2}, and SrCl{sub 2}. The onset of the observed prominent excited-state absorption band is consistent with an electrostatic model for impurity levels in a solid-state material. 15 refs., 4 figs., 1 tab.
Date: April 1, 1991
Creator: Lawson, J. K.; Lee, H. W. H.; Payne, S. A. (Lawrence Livermore National Lab., CA (United States)) & Boatner, L. A. (Oak Ridge National Lab., TN (United States))
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Partner: UNT Libraries Government Documents Department
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Technical basis, supporting information, and strategy for development and implementation of DOE policy for natural phenomena hazards

Description: Policy for addressing natural phenomenon comprises a hierarchy of interrelated documents. The top level of policy is contained in the code of Federal Regulations which establishes the framework and intent to ensure overall safety of DOE facilities when subjected to the effects of natural phenomena. The natural phenomena to be considered include earthquakes and tsunami, winds, hurricanes and tornadoes, floods, volcano effects and seiches. Natural phenomena criteria have been established for desi… more
Date: September 1, 1991
Creator: Murray, R. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Polarization spectroscopy of tokamak plasmas

Description: Measurements of polarization of spectral lines emitted by tokamak plasmas provide information about the plasma internal magnetic field and the current density profile. The methods of polarization spectroscopy, as applied to the tokamak diagnostic, are reviewed with emphasis on the polarimetry of motional Stark effect in hydrogenic neutral beam emissions. 25 refs., 7 figs.
Date: September 1, 1991
Creator: Wroblewski, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Investigation of strain birefringence and wavefront distortion in 001 plates of KD sub 2 PO sub 4

Description: When 001 plates of KD{sub 2}PO{sub 4} (KD*P) are used in Pockels cells, strain induced refractive index variations result in beam depolarization and transmitted wavefront distortion. The depolarization is determined by the induced birefringence while the wavefront distortion is controlled by the average index shift. Here we show that the birefringence is determined by the shear stress in the xy-plane of the crystal while the average index shift depends only on the normal stresses. Furthermore, … more
Date: August 26, 1991
Creator: De Yoreo, J. J. & Woods, B. W.
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Partner: UNT Libraries Government Documents Department
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Enhanced lower hybrid penetration via intense multi-microsecond pulses

Description: Applying lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present theoretical description of the absorption which accounts for transient collisional effects as well as nonlinear broadening of the resonant plateau. We show results from ray-tracing calculations which include the nonlinear absorption. We also derive the conditions required for pump depletion by parametric instabilities, and assess density deple… more
Date: January 1, 1991
Creator: Cohen, R. H.; Rognlien, T. D. (Lawrence Livermore National Lab., CA (United States)); Bonoli, P. T. & Porkolab, M. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)
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Partner: UNT Libraries Government Documents Department
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A guide to writing procurement specifications for new and existing CHAWS sites

Description: Turn-key Chemical Hazard Warning Systems (CHAWS) have been designed by the Lawrence Livermore National Laboratory (LLNL) and installed at a number of US Army sites. This document is intended to be used as a guide by those charged with writing procurement specification for both new and existing CHAWS sites. It discusses issues of system design and the functional requirements for both hardware and software. Suggestions are made for those interested in updating the computer platform and/or operati… more
Date: September 1, 1991
Creator: Martins, S.A. & Fry, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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An analysis of grazing incidence metal mirrors in a laser ICF reactor driver

Description: Grazing incidence metal mirrors (GIMMs) are examined to replace dielectric mirrors for the final elements in a laser beam line for an inertial confinement fusion reactor. For a laser driver with a wavelength from 250 to 500 nm in a 10-ms pulse, irradiated mirrors made of Al, Al alloys, or Mg were found to have calculated laser damage limits of 0.3--2.3 J/cm{sup 2} of beam energy and neutron lifetime fluence limits of over 5 {times} 10{sup 20} 14 MeV n/cm{sup 2} when used at grazing incidence an… more
Date: July 12, 1991
Creator: Bieri, R. & Guinan, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dielectronic recombination measurements of highly-charged heliumlike and neonlike ions using an electron beam ion trap

Description: The electron beam ion trap (EBIT) at LLNL is a unique device designed to measure the interactions of electrons with highly-charged ions. We describe three methods used at EBIT to directly measure the dielectronic recombination (DR) process: the intensity of the stabilizing x-rays is measured as a function of electron beam energy; the ions remaining in a particular ionization state are counted after the electron beam has been held at a fixed electron energy for a fixed time; and high-resolution … more
Date: January 1, 1991
Creator: Schneider, M. B.; Knapp, D. A.; Beiersdorfer, P.; Chen, M. H.; Scofield, J. H.; Bennett, C. L. et al.
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Partner: UNT Libraries Government Documents Department
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ECH propagation and absorption experiments at 140 GHz in MTX

Description: Single pass absorption experiments using fundamental, O-mode ECH waves have been performed in the Microwave Tokamak Experiment (MTX) and found to be consistent with linear absorption theory, as predicted for the ECH source which is a 140 GHz, 400 kW CW gyrotron. These experiments provide the basis for comparison with future Free Electron Laser (FEL) experiments in which the absorption is predicted to be in the non-linear regime for P{sub FEL} {ge} 1 GW. The gyrotron power is coupled into a quas… more
Date: August 1, 1991
Creator: Fenstermacher, M. E.; Allen, S. L.; Casper, T. A.; Foote, J. H.; Hooper, E. B.; Johnston, S. et al.
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Partner: UNT Libraries Government Documents Department
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Broadband diffractive lens

Description: Significant progress has been made toward solving the century-old problem of chromatic aberrations in diffractive optics. Our approach exploits modern materials and microfabrication technology and is very different from the purely diffractive strategy,'' which is commonly employed and which results in multiple diffractive elements separated by a finite distance. We have developed a Fresnel zone plate lens comprised of a serial stack of patterned minus-filters which allows broadband radiation to… more
Date: May 28, 1991
Creator: Ceglio, N. M.; Hawryluk, A. M.; London, R. A.; Seppala, L. G. (Lawrence Livermore National Lab., CA (USA)) & Gaines, D. P. (Brigham Young Univ., Provo, UT (USA))
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Partner: UNT Libraries Government Documents Department
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Thulium-170 heat source

Description: An isotopic heat source is formed using stacks of thin individual layers of a refractory isotopic fuel, preferably thulium oxide, alternating with layers of a low atomic weight diluent, preferably graphite. The graphite serves several functions: to act as a moderator during neutron irradiation, to minimize bremsstrahlung radiation, and to facilitate heat transfer. The fuel stacks are inserted into a heat block, which is encased in a sealed, insulated and shielded structural container. Heat pipe… more
Date: September 6, 1990
Creator: Walter, Carl E.; Van Konynenburg, Richard & VanSant, James H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Superplasticity in a nickel silicide alloy: Microstructural and mechanical correlations

Description: The superplastic properties of a nickel silicide based intermetallic alloy have been investigated as a function of strain, strain-rate, and temperature. The evolution of the microstructure during superplasticity, including grain growth, grain refinement, and cavitation, is reviewed. The relationship of the flow stress to strain and to strain-rate and the activation energy of the deformation process have been established. Finally, deformation mechanisms for superplasticity in the alloy at interm… more
Date: January 1, 1991
Creator: Stoner, S.L. (Lawrence Livermore National Lab., CA (United States)); Oliver, W.C. (Oak Ridge National Lab., TN (United States)) & Mukherjee, A.K. (California Univ., Davis, CA (United States). Dept. of Mechanical, Aeronautical and Materials Engineering)
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Partner: UNT Libraries Government Documents Department
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Ground wave propagation of a video pulse source: Part 2

Description: In a previous paper we developed a simple model describing the far-field from a video-pulse source near the ground and for grazing incidence. We report here on a recent field test in which we attempted to verify the model. Our results show quantitative agreement with the model for most of the tested parameter space. We have also extended our model to include all elevation angles, including up to vertical. The computed engagement envelope shows three distinct regions: At grazing angles the field… more
Date: July 19, 1991
Creator: Dreyer, K. A. & Buettner, H. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Inherently safe nuclear-driven internal combustion engines

Description: A family of nuclear driven engines is described in which nuclear energy released by fissioning of uranium or plutonium in a prompt critical assembly is used to heat a working gas. Engine performance is modeled using a code that calculates hydrodynamics, fission energy production, and neutron transport self-consistently. Results are given demonstrating a large negative temperature coefficient that produces self-shutoff of energy production. Reduced fission product inventory and the self-shutoff … more
Date: June 14, 1991
Creator: Alesso, P.; Chow, Tze-Show; Condit, R.; Heidrich, J.; Pettibone, J. & Streit, R.
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Partner: UNT Libraries Government Documents Department
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High-intensity photoionization of H sub 2

Description: A tunable, high-intensity picosecond dye laser system has been employed with electron energy analysis to investigate the dynamics of (3+1) resonance-enhanced multiphoton ionization of H{sub 2} via different vibrational levels of its B{sub 1}{Sigma}{sub u}{sup +} and C{sup 1}{Pi}{sub u} electronic states. We observe production of molecular ions in various vibrational levels, with a shift to increased population of lower vibrational states of H{sub 2}{sup +} consistent with the a.c. Stark shift o… more
Date: May 1, 1991
Creator: Allendorf, S.W. & Szoeke, A.
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Partner: UNT Libraries Government Documents Department
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Energetics and statistics of order in alloys with application to oxide superconductors

Description: Now that first-principles calculations of ordering transformations are becoming increasingly accurate, the deficiencies of earlier mean field methods are becoming increasingly apparent. New techniques, based on cluster expansions, are now alleviating many of the earlier problems and are producing very satisfactory results. These ideas will be illustrated for the case of oxygen ordering in the YBa{sub 2}Cu{sub 3}O{sub z} superconducting compound, for which a very simple two-dimensional Ising mod… more
Date: June 1, 1991
Creator: de Fontaine, D. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering) & Asta, M. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States).
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Partner: UNT Libraries Government Documents Department
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Cross-borehole and surface-to-borehole electromagnetic induction for reservoir characterization

Description: Audio-frequency cross-borehole and surface-to-borehole electromagnetics (EM) are interesting alternatives to existing techniques for petroleum reservoir characterization and monitoring. With these methods signals may be propagated several hundreds of meters through typical sand/shale reservoirs and data may be collected at high accuracy with a high sensitivity to the subsurface resistivity distribution. Field systems for cross-borehole and surface-to-borehole EM measurements have been designed … more
Date: August 1, 1991
Creator: Wilt, M. J.; Morrison, H. F.; Becker, A. & Lee, K. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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