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Mark Vii-a Fuel Slugs--Computer Surveillance of Crystallographic Orientation

Description: Natural uranium fuel slugs are produced by a cortrolled process and definite averages and standard deviations exist for x-ray diffraction data. A change in a production variable, such as heat treatment, is readily discernible through statistical quality control. Programs for the IBM 1401 computer were developed which compute the average values and 3-sigma limits for texture coefficient and G3 growth index data. This information is updated weekly and is plotted by the computer in the form of average (X) and range (R) charts. Each month, an exception report and a G3 index are computed. These show only those charts which had X or R factors exceedirg 3-sigma limits during the month. Thus, trends are revealed in the crystallographic orientation characteristics of fuel slugs. (auth)
Date: November 1, 1962
Creator: Wood, R. S., Jr.
Partner: UNT Libraries Government Documents Department

Single, stretched membrane, structural module experiments

Description: This report describes tests done on stretched-membrane heliostats used to reflect solar radiation onto a central receiver. The tests were used to validate prior analysis and mathematical models developed to describe module performance. The modules tested were three meters in diameter and had reflective polymer film laminated to the membrane. The frames were supported at three points equally spaced around the ring. Three modules were pneumatically attached with their weight suspended at the bottom support, two were pneumatically attached with their weight suspended from the upper mounts, and one was rigidly attached with its weight suspended at the bottom mount. By varying the membrane tension we could simulate a uniform wind loading normal to the mirror's surface. A video camera 15+ meters away from the mirror recorded the virtual image of a target grid as reflected by the mirrors' surface. The image was digitized and stored on a microcomputer. Using the law of reflection and analytic geometry, we computed the surface slopes of a sampling of points on the surface. The dominant module response was consistent with prior SERI analyses. The simple analytical model is quite adequate for designing and sizing single-membrane modules if the initial imperfections and their amplification are appropriately controlled. To avoid potential problems resulting from the fundamentally n = 2 deformation phenomena, we advise using either relatively stiffer ring frames or more than three support points.
Date: February 1, 1986
Creator: Wood, R.L.
Partner: UNT Libraries Government Documents Department

Development of an experimental database and theories for prediction of thermodynamic properties of aqueous electrolytes and nonelectrolytes of geochemical significance at supercritical temperatures and pressures

Description: Volumetric measurements have been completed for CH{sub 4}, CO{sub 2}, and H{sub 2}S at temperatures from 25{degrees}C to 380{degrees}C and 2 or 3 pressures at each temperature. The H{sub 2}S and CO{sub 2} solutions are stored in aluminized mylar bags in PVC pipes with water surrounding the bags at a pressure of several atmospheres. The methane is stored in a one liter autoclave with a sliding teflon piston engaging the sides of the autoclave which separates the standard methane solution from the pressurizing fluid. The solutions are prepared at 100 to 200 atmospheres and do not need to be re-standardized after each experiment. We also have some measurements on aqueous ammonia, boric acid, and acetic acid. Preliminary calculations of the free energy of methane in water at room temperature as a function of the model parameters for the methane have been finished. In preparation for these calculations, the theory and practice of the free energy perturbation calculations was reviewed. In molecular dynamics and Monte Carlo calculations a system does not immediately equilibrate to a change in the Hamiltonian, so that there is a time lag or a configuration number lag in the response of the system. These lags cause errors in free energy calculations. 4 refs.
Date: May 2, 1991
Creator: Wood, R.H.
Partner: UNT Libraries Government Documents Department

Modeling of complex melting and solidification behavior in laser-irradiated materials (a description and users guide to the LASER8 computer program)

Description: The conceptual foundation of a computational model and a computer program based on it have been developed for treating various aspects of the complex melting and solidification behavior observed in pulsed laser-irradiated materials. A particularly important feature of the modeling is the capability of allowing melting and solidification to occur at temperatures other than the thermodynamic phase change temperatures. As a result, interfacial undercooling and overheating can be introduced and various types of nucleation events can be simulated. Calculations on silicon with the model have shown a wide variety of behavior, including the formation and propagation of multiple phase fronts. Although originally developed as a tool for studying certain problems arising in the field of laser annealing of semiconductors, the program should be useful in treating many types of systems in which phase changes and nucleation phenomena play important roles. This report describes the underlying physical and mathematical ideas and the basic relations used in LASER8. It also provides enough specific and detailed information on the program to serve as a guide for its use; a listing of one version of the program is given.
Date: November 1, 1985
Creator: Geist, G.A. & Wood, R.F.
Partner: UNT Libraries Government Documents Department

Theoretical calculations of the electronic and vibrational structure of point defects in ionic crystals

Description: The structure of the Hartree-Fock one-electron equations for simple point defects in ionic crystals are discussed. The importance of polarization effects due to the diffuse nature of the wavefunctions in the relaxed excited states are emphasized, and the usefulness of an effective mass approximation indicated. Several approaches to the calculation of the electronic structure are discussed and evaluated. The connection between electronic structure calculations and phonon perturbations are pointed out through a brief discussion of localized perturbation theory.
Date: January 1, 1981
Creator: Wood, R.F. & Wilson, T.M.
Partner: UNT Libraries Government Documents Department

Protection circuits for superconducting magnets

Description: As the technology of controlled nuclear fusion progresses, plans for new experimental reactors include much longer duty cycles than those of earlier experiments. Many of the magnet systems for these reactors must be superconducting due to the prolonged or continuous high current levels required. The large initial investment of a superconducting magnet system justifies a protective dump circuit. This circuit must operate if the magnet goes normal or in the event of failure of some of the critical auxiliary equipment. This paper examines two applications of superconducting magnet protection for fusion experiments. A novel dc interrupter being developed especially for this purpose is also discussed.
Date: January 1, 1980
Creator: Parsons, W.M. & Wood, R.J.
Partner: UNT Libraries Government Documents Department

Modified laser-annealing process for improving the quality of electrical P-N junctions and devices

Description: The invention is a process for producing improved electrical-junction devices. The invention is applicable, for example, to a process in which a light-sensitive electrical-junction device is produced by: (1) providing a body of crystalline semiconductor material having a doped surface layer; (2) irradiating the layer with at least one laser pulse to effect melting of the layer; (3) permitting recrystallization of the melted layer; and (4) providing the resulting body with electrical contacts. In accordance with the invention, the fill-factor and open-circuit-voltage parameters of the device are increased by conducting the irradiation with the substrate as a whole at a selected elevated temperature, the temperature being selected to effect a reduction in the rate of the recrystallization but insufficient to effect substantial migration of impurities within the body. In the case of doped silicon substrates, the substrate may be heated to a temperature in the range of from about 200/sup 0/C to 500/sup 0/C.
Date: February 19, 1982
Creator: Wood, R.F. & Young, R.T.
Partner: UNT Libraries Government Documents Department

Studies of pulsed laser melting and rapid solidification using amorphous silicon

Description: Pulsed-laser melting of ion implantation-amorphized silicon layers, and subsequent solidification were studied. Measurements of the onset of melting of amorphous silicon layers and of the duration of melting, and modified melting model calculations demonstrated that the thermal conductivity, K/sub a/, of amorphous silicon is very low (K/sub a/ approx. = 0.02 W/cm-K). K/sub a/ is also the dominant parameter determining the dynamical response of amorphous silicon to pulsed laser radiation. TEM indicates that bulk (volume) nucleation occurs directly from the highly undercooled liquid silicon that can be prepared by pulsed laser melting of amorphous silicon layers at low laser energy densities. A modified thermal melting model is presented. The model calculations demonstrate that the release of latent heat by bulk nucleation occurring during the melt-in process is essential to obtaining agreement with observed depths of melting. These calculations also show that this release of latent heat accompanying bulk nucleation can result in the existence of buried molten layers of silicon in the interior of the sample after the surface has solidified. The bulk nucleation implies that the liquid-to-amorphous phase transition (produced using picosecond or uv nanosecond laser pulses) cannot be explained using purely thermodynamic considerations.
Date: June 1, 1984
Creator: Lowndes, D.H. & Wood, R.F.
Partner: UNT Libraries Government Documents Department

Fundamental aspects of pulsed-laser irradiation of semiconductors

Description: Fundamental aspects of pulsed laser melting and solidification of crystalline silicon and germanium are reviewed. The discussion concentrates on time-resolved experiments performed with nanosecond pulsed lasers, although some picosecond and femtosecond experiments are also considered. The creation of amorphous material from crystalline material induced by ultrarapid melting and resolidification using either nanosecond or picosecond lasers is surveyed and the inverse process of recrystallization of a-Si by explosive crystallization is described. Finally, melting model calculations, which have proven to give a very accurate description of the pulsed laser irradiation process, are discussed.
Date: August 1, 1986
Creator: Jellison, G.E. Jr.; Lowndes, D.H. & Wood, R.F.
Partner: UNT Libraries Government Documents Department


Description: As part of the Low-Energy Demonstration Accelerator (LEDA) portion of the Advanced Accelerator Applications (AAA) project we have fabricated and will perform high-power RF tests on Section 2 of the 700-MHz Coupled-Cavity Drift-Tube Linac (CCDTL). This CCDTL section contains six, two-gap accelerating cells. This portion of the CCDTL was designed to accelerate the 100-mA, LEDA RFQ proton beam to 7.3 MeV. This paper reports on the process and results of tuning Section 2 leading up to high-power RF testing.
Date: June 1, 2001
Creator: Rybarcyk, L. & Wood, R
Partner: UNT Libraries Government Documents Department

Real-time computer analysis for nuclear material detection. Part 3. Nuclear instrumentation interface

Description: An electronic interface between a Digital Equipment Corporation (DEC) LSI-11 microcomputer and a LeCroy Research Systems model 3001 qVt multichannel analyzer is described in detail. This interface provides for 16-bit parallel data transfer from the memory of the analyzer to the memory of the computer. An unusual feature of the interface is a provision that allows storage of counts of logic pulses (e.g., from radiation detector discriminators) in the first 16 channels of the analyzer's memory. A further provision allows use of a LeCroy printer and display interface that is designed specifically as a companion module to the qVt analyzer.
Date: December 1, 1981
Creator: Gosnell, T.B.; Wood, R.E. & Anzelon, G.A.
Partner: UNT Libraries Government Documents Department

Magnetic shielding tests for MFTF-B neutral beamlines

Description: A test program to determine the effectiveness of various magnetic shielding designs for MFTF-B beamlines was established at Lawrence Livermore National Laboratory (LLNL). The proposed one-tenth-scale shielding-design models were tested in a uniform field produced by a Helmholtz coil pair. A similar technique was used for the MFTF source-injector assemblies, and the model test results were confirmed during the Technology Demonstration in 1982. The results of these tests on shielding designs for MFTF-B had an impact on the beamline design for MFTF-B. The iron-core magnet and finger assembly originally proposed were replaced by a simple, air-core, race-track-coil, bending magnet. Only the source injector needs to be magnetically shielded from the fields of approximately 400 gauss.
Date: November 16, 1983
Creator: Kerns, J.; Fabyan, J.; Wood, R. & Koger, P.
Partner: UNT Libraries Government Documents Department

Modeling and simulation of energy-removal system for superconducting magnets

Description: The Large Coil Test Facility at the Oak Ridge National Laboratory employs six D shaped superconducting coils. The coil current ranges from 10 to 20 kA. The protection scheme of these coils requires the coil current to be interrupted. This interruption will generate high-voltage transients in the coil. To prevent destruction of the coil isolation, these transients have to be reduced. Two types of suppressor networks, one a varistor and the other an R-C network, were reviewed. Then each suppressor circuit was simulated to determine the effectiveness of each suppressor. The modelling used the Super Sceptre computer program to simulate these transients.
Date: January 1, 1983
Creator: Bailey, J.M.; Googe, J.M. & Wood, R.J.
Partner: UNT Libraries Government Documents Department

Applications of laser annealing and laser-induced diffusion to photovoltaic conversion

Description: Over the past several years it has been demonstrated that a variety of techniques involving pulsed laser irradiation of both single crystal and polycrystalline silicon by pulsed lasers can result in the reproducible achievement of high efficiency silicon solar cells. Pulsed laser annealing (PLA) after an ion implantation (II) step results in melting (for a time of order 100 nsec) and essentially defect-free liquid phase epitaxial regrowth within approx. 0.5 ..mu..m of the surface. Complete electrical activation of a number of dopant ions, at concentrations exceeding ordinary solubility limits, has been demonstrated and crystalline (polycrystalline) silicon solar cell efficiencies of 16.6% (12.5%) have been obtained. Other p-n junction and solar cell fabrication techniques have been demonstrated. Pulsed laser processing has also been demonstrated to have several other unique and beneficial advantages in polycrystalline silicon substrates. For example, grain boundaries do not exist during laser melting, while dopant diffusion is taking place; the short melt durations involved further limit dopant diffusion; precipitates present after conventional high temperature dopant diffusion can be removed; and, certain types of electrically active grain boundaries can be made inactive by pulsed laser irradiation. Finally, grain growth in fine-grained polycrystalline silicon films, via pulsed laser melting and recrystallization, has been demonstrated. Because little is known about the application of similar pulsed laser processing techniques to compound semiconductors, particularly in connection with the formation of shallow p-n junctions, research has been devoted to studies of pulsed laser processing of GaAs and compound semiconductor solar cell fabrication techniques that are compatible with the use of pulsed lasers. Progress is reported. (WHK)
Date: January 1, 1981
Creator: Lowndes, D.H.; Young, R.T. & Wood, R.F.
Partner: UNT Libraries Government Documents Department

Control of Airplanes at Low Speeds

Description: Loss of control over the orientation of an airplane as the incidence approaches and enters the region of stalled flight is a prolific cause of serious accidents. This report discusses methods of landing at slow speeds approaching stall.
Date: September 1923
Creator: Wood, R. McKinnon
Partner: UNT Libraries Government Documents Department

Livermore Computing Production Control System, 3.0: Product description. Revision 1

Description: The purpose of this document is to introduce and describe the Livermore Computing Production Control System, commonly called the PCS. Resource management is very difficult in typical UNIX and related systems. The weakness involves the allocation, control and delivery of the usage of computer resources. Accounting also is weak, being generally limited to reporting that a user used an amount of time on a process. A process accounting record is made only after the completion of a process and then only if the process does not terminate as a result of a system panic. Resources can only be allocated to users. No cognizance can be taken of organizational structure or projects. Allocations cannot be managed at these levels. Denying service to a user who has access to a machine is crude. Large computing centers frequently have thousands of users working on hundreds of projects. These users and the projects are funded by several organizations with varying ability or willingness to pay for the computer services provided. With only typical UNIX tools, the appropriate delivery of resources to the correct organizations, projects, tasks and users requires continual human intervention. UNIX and related systems have become increasingly more reliable over the past few years. A consequence of this is that resource managers and accountants have been presented with an attendant problem of accurate accounting for resources used. Processes can now run for days or months without terminating. A run-away process or a malicious or uninformed user can use an organization`s budgeted resource allocation many times over before an accounting record to that effect is written. If a process`s accounting record is not written because of a panic, the computer center is faced with possibly significant financial loss.
Date: November 1, 1993
Creator: Wood, R. R.
Partner: UNT Libraries Government Documents Department

Pulsed-laser annealing of ion-implanted GaAs: theory and experiment

Description: It is shown that, in the pulsed-laser irradiation of crystalline or lightly damaged GaAs, good agreement is obtained between measured and calculated thresholds for melting, for catastrophic damage due to vaporization, and for the duration of surface melting at various energy densities. Good agreement between theory and experiment is also obtained for dopant profile spreading during pulsed-laser annealing.
Date: November 1, 1980
Creator: Wood, R.F.; Lowndes, D.H. & Christie, W.H.
Partner: UNT Libraries Government Documents Department

Mercury Removal at Idaho National Engineering and Environmental Laboratory's New Waste Calcining Facility

Description: Technologies were investigated to determine viable processes for removing mercury from the calciner (NWCF) offgas system at the Idaho National Engineering and Environmental Laboratory. Technologies for gas phase and aqueous phase treatment were evaluated. The technologies determined are intended to meet EPA Maximum Achievable Control Technology (MACT) requirements under the Clean Air Act and Resource Conservation and Recovery Act (RCRA). Currently, mercury accumulation in the calciner off-gas scrubbing system is transferred to the tank farm. These transfers lead to accumulation in the liquid heels of the tanks. The principal objective for aqueous phase mercury removal is heel mercury reduction. The system presents a challenge to traditional methods because of the presence of nitrogen oxides in the gas phase and high nitric acid in the aqueous scrubbing solution. Many old and new technologies were evaluated including sorbents and absorption in the gas phase and ion exchange, membranes/sorption, galvanic methods, and UV reduction in the aqueous phase. Process modifications and feed pre-treatment were also evaluated. Various properties of mercury and its compounds were summarized and speciation was predicted based on thermodynamics. Three systems (process modification, NOxidizer combustor, and electrochemical aqueous phase treatment) and additional technology testing were recommended.
Date: March 1, 2000
Creator: Ashworth, Samuel Clay; Wood, R. A.; Taylor, D. D. & Sieme, D. D.
Partner: UNT Libraries Government Documents Department

Sustained spheromak coaxial gun operation in the presence of an n=1 magnetic distortion

Description: The Sustained Spheromak Physics Experiment (SSPX) uses a magnetized coaxial gun to form and sustain spheromaks by helicity injection. Internal probes give the magnetic profile within the gun. Analysis of these data show that a number of commonly applied assumptions are not completely correct, and some previously unrecognized processes may be at work. Specifically, the fraction of the available vacuum flux spanning the gun that is stretched out of the gun is variable and not usually 100%. The n=1 mode that is present during sustained discharges has its largest value of {delta}B/B within the gun, so that instantaneously B within the gun is not axisymmetric. By applying a rigid-rotor model to account for the mode, the instantaneous field and current structure within the gun are determined. The current density is also highly non-axisymmetric and the local value of {lambda} {triple_bond} {mu}{sub 0}j{sub {parallel}}/B is not constant, although the global value {lambda}{sub g} {triple_bond} {mu}{sub 0}I{sub g}/{psi}{sub g} closely matches that expected by axisymmetric models. The current distribution near the gun muzzle suggests cross-field current exists, and this is explained as a line-tying reaction to plasma rotation.
Date: September 6, 2005
Creator: Holcomb, C T; Jarboe, T R; Hill, D N; Woodruff, S & Wood, R D
Partner: UNT Libraries Government Documents Department