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 measurements using the CORSICA code. Density and impurity control is obtained using baking, glow discharge cleansing, and titanium gettering, after which long plasma decay times ({tau} {ge} 1.5ms) are observed and impurity radiation losses are reduced from {approx}50% to <20% of the input energy. Thomson scattering measurements show peaked electron temperature and pressure profiles with T{sub e} (0){approx}120eV and {beta}{sub e}{approx}7%. Edge field measurements show the presence of n=1 modes during the formation phase, as has been observed in other spheromaks. This mode dies away during sustainment and decay so that edge fluctuation levels as low as 1% have been measured. These results are compared with numerical simulations using the NIMROD code.

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We have developed a methodology for predicting combustion and emissions in a Homogeneous Charge Compression Ignition (HCCI) Engine. This methodology combines a detailed fluid mechanics code with a detailed chemical kinetics code. Instead of directly linking the two codes, which would require an extremely long computational time, the methodology consists of first running the fluid mechanics code to obtain temperature profiles as a function of time. These temperature profiles are then used as input to a multi-zone chemical kinetics code. The advantage of this procedure is that a small number of zones (10) is enough to obtain accurate results. This procedure achieves the benefits of linking the fluid mechanics and the chemical kinetics codes with a great reduction in the computational effort, to a level that can be handled with current computers. The success of this procedure is in large part a consequence of the fact that for much of the compression stroke the chemistry is inactive and thus has little influence on fluid mechanics and heat transfer. Then, when chemistry is active, combustion is rather sudden, leaving little time for interaction between chemistry and fluid mixing and heat transfer. This sequential methodology has been capable of explaining the main …

This article discusses an analysis of ultraviolet observations with the FAUST shuttle-borne telescope toward the Antennae and NGC 6752 celestial regions resulting in the detection of 46 and 221 candidate sources respectively, for a signal-to-noise ratio of 8.

Effect of extrusion temperatures on the microstructural development of a powder metallurgy (PM) Ti-47Al-2Cr-1Nb-1Ta (at. %) alloy has been investigated. Microstructure of the PM alloy extruded at 1150 C consists of a fine-grained ({gamma} + {alpha}{sub 2}) two-phase structure in association with coarse grains of metastable B2 (ordered bcc) phase. In addition, fine {omega} (ordered hexagonal) particles are also found within some B2 grains. The PM alloy containing the metastable B2 grains displays a low-temperature superplastic behavior, in which a tensile elongation of 310% is obtained at 800 C under a strain rate of 2 x 10{sup -5} s{sup -1}. It is suggested that the decomposition of metastable B2 phase and microstructural evolution during the deformation play a crucial role in the low-temperature superplasticity of the PM TiAl alloy. A refined fully-lamellar (FL) microstructure with alternating {gamma} and {alpha}{sub 2} lamellae is developed within the PM alloy extruded at 1400 C. The creep resistance of the refined FL-TiAl alloy is found to be superior to those of the TiAl alloys fabricated by conventional processing techniques. Creep mechanisms for the PM alloy with a refined FL microstructure are critically discussed according to TEM examination of deformation substructure.

The technical basis and stakeholder acceptance of entombment technology is necessary before entombment becomes a decontamination and decommissioning (D and D) option for nuclear reactors. The authors present a research and development (R and D) approach addressing technical basis and stakeholder acceptance of entombment technology. The approach includes a consortium and the conceptual R and D program.

The FRIS/PINS hybrid integrates the LLNL-developed Field Radionuclide Identification System (FRIS) with the INEEL-developed Portable Isotopic Neutron Spectroscopy (PINS) chemical assay system to yield a combined general radioisotope, special nuclear material, and chemical weapons/explosives detection and identification system. The PINS system uses a neutron source and a high-purity germanium {gamma}-ray detector. The FRIS system uses an electrochemically cooled germanium detector and its own analysis software to detect and identify special nuclear material and other radioisotopes. The FRIS/PINS combined system also uses the electromechanically-cooled germanium detector. There is no other currently available integrated technology that can combine an active neutron interrogation and analysis capability for CWE with a passive radioisotope measurement and identification capability for special nuclear material.

Gamma rays are ideal probes for the determination of information about the special nuclear material that is in the transparency regime. Gamma rays are good probes because they interact relatively weakly with the containers that surround the SNM under investigation. In addition, gamma rays carry a great deal of information about the material under investigation. We have leveraged these two characteristics to develop three technologies that have proven useful for the measurements of various attributes of plutonium. These technologies are Pu-300, Pu-600 and Pu-900. These technologies obtain the age, isotopics and presence/absence of oxide of a plutonium sample, respectively. Pu-300 obtains the time since the last {sup 241}Am separation for a sample of plutonium. This is accomplished by looking at the {sup 241}Am/{sup 241}pu ratio in the energy region from 330-350 keV, hence the name Pu-300. Pu-600 determines the isotopics of the plutonium sample under consideration. More specifically, it determines the {sup 240}Pu/{sup 239}Pu ratio to determine if the plutonium sample is of weapons quality or not. This analysis is carded out in the energy region from 630-670 keV. Pu-900 determines the absence of PuO{sub 2} by searching for a peak at 870.7 keV. If this peak is absent then …

A great variety of numerical methods have been employed to solve the Schroedinger equation, the basic equation of theoretical atomic physics. Being a three body problem, the scattering of an incoming antiproton (p{sup -}) by a hydrogen atom (H, consisting of an electron, e{sup -}, bound to a proton, p) is one of the simplest problems in field of atomic theory that requires a numerical solution. Described and compared here are three methods, valid in essentially separate energy ranges from zero energy through MeV energies, that illustrate how numerical methods are employed in this field. In spite of this problem's seeming simplicity, much effort is required in terms of mathematical manipulation and use of approximations to render it capable of numerical solution.

We present a new algorithm for material boundary interface reconstruction from data sets containing volume fractions. We transform the reconstruction problem to a problem that analyzes the dual data set, where each vertex in the dual mesh has an associated barycentric coordinate tuple that represents the fraction of each material present. After constructing the dual tetrahedral mesh from the original mesh, we construct material boundaries by mapping a tetrahedron into barycentric space and calculating the intersections with Voronoi cells in barycentric space. These intersections are mapped back to the original physical space and triangulated to form the boundary surface approximation. This algorithm can be applied to any grid structure and can treat any number of materials per element/vertex.

A series of experiments is described in which a novel prescription for the identification of plastic strain is tested to determine its validity in the context of the strain-space formulation of rate-independent plasticity. Biaxial experiments were performed on several thin-walled aluminum 1100-O cylindrical specimens.

This paper presents results obtained by using a method of profiling a user based on the login host, the login time, the command set, and the command set execution time of the profiled user. It is assumed that the user is logging onto a UNIX host on a computer network. The paper concentrates on two areas: short-term and long-term profiling. In short-term profiling the focus is on profiling the user at a given session where user characteristics do not change much. In long-term profiling, the duration of observation is over a much longer period of time. The latter is more challenging because of a phenomenon called concept or profile drift. Profile drift occurs when a user logs onto a host for an extended period of time (over several sessions).

A drift-scale distinct element model (DSDE) is being used to analyze geomechanical behavior in the Drift Scale Test (DST) now underway at Yucca Mountain, Nevada. The DST is a large-scale, long-term thermal test designed to investigate coupled thermal-mechanical-hydrological-chemical behavior in a fractured, welded tuff rock mass. Electric heaters are being used to heat a 50 m length of drift for 4 years, followed by 4 years of cooling. The target drift wall temperature is 200 C during much of the heating period. The distinct element method was chosen to permit explicit modeling of fracture deformations. Shear deformations and normal mode opening of fractures are expected to increase fracture permeability and thereby alter thermal-hydrologic behavior in the DST region. This paper will describe the DSDE model and present preliminary modeling results, including temperature and stress fields, and normal and shear fracture displacements at a series of times after start of heating. Figure 1 shows the drift geometry and associated fracture planes used in the simulations. The fracture locations and orientations were determined by analysis of borehole video logs. Predicted normal mode fracture deformations are concentrated along and above the heated drift (Figure 2). The results indicate similar magnitudes and spatial distributions …

We discuss the extension of the powerful technique of Thomson scattering to the x-ray regime for providing an independent measure of plasma parameters for dense plasmas. By spectrally-resolving the scattering, the coherent (Rayleigh) unshifted scattering component can be separated from the incoherent Thomson component, which is both Compton and Doppler shifted. The free electron density and temperature can then be inferred from the spectral shape of the high frequency Thomson scattering component. In addition, as the plasma temperature is decreased, the electron velocity distribution as measured by incoherent Thomson scattering will make a transition from the traditional Gaussian Boltzmann distribution to a density-dependent parabolic Fermi distribution to. We also present a discussion for a proof-of-principle experiment appropriate for a high energy laser facility.

Article on kinetic and modeling studies of the reaction of hydroxyl radicals with tetrachloroethylene.

Article on the solubility of anthracene in ternary methyl tert-butyl ether + alcohol + heptane solvent mixtures at 298.15 K.

Article on the solubility of anthracene in ternary methyl tert-butyl ether + alcohol + 2,2,4-trimethylpentane solvent mixtures at 298.15 K.

Ultra-thin oxynitride films were grown on Si by direct rapid thermal processing (RTP) oxynitridation in NO/O{sub 2} ambients with NO concentrations from 5% to 50%. During oxynitridation, nitrogen accumulated at the Si/dielectric interface and the average concentration of in N through the resulting films ranged from 0.3 to 3.0 atomic percent. The average concentration of N in the films increased with increasing NO in the ambient gas, but decreased with longer RTP times. The maximum N concentration remained relatively constant for all RTP times and a given NO/O{sub 2} ambient. Re-oxidation following oxynitridation altered L the N profile and improved the electrical characteristics, with an optimal NO/O{sub 2} mixture in the range of 10% to 25% NO. Re-oxidation by RTP improves the electrical characteristics with respect to the films that were not re-oxidized and produces only slight changes in the N distribution or maximum concentration. The electrical results also indicate that oxynitride films are superior to comparably grown oxide films.

A unified set of high-temperature-hohlraum models has been developed. For a simple hohlraum, P{sub s} = [A{sub s}+(1{minus}{alpha}{sub W})A{sub W}+A{sub H}]{sigma}T{sub R}{sup 4} + (4V{sigma}/c)(dT{sub R}{sup r}/dt) where P{sub S} is the total power radiated by the source, A{sub s} is the source area, A{sub W} is the area of the cavity wall excluding the source and holes in the wall, A{sub H} is the area of the holes, {sigma} is the Stefan-Boltzmann constant, T{sub R} is the radiation brightness temperature, V is the hohlraum volume, and c is the speed of light. The wall albedo {alpha}{sub W} {triple_bond} (T{sub W}/T{sub R}){sup 4} where T{sub W} is the brightness temperature of area A{sub W}. The net power radiated by the source P{sub N} = P{sub S}-A{sub S}{sigma}T{sub R}{sup 4}, which suggests that for laser-driven hohlraums the conversion efficiency {eta}{sub CE} be defined as P{sub N}/P{sub LASER}. The characteristic time required to change T{sub R}{sup 4} in response to a change in P{sub N} is 4V/C[(l{minus}{alpha}{sub W})A{sub W}+A{sub H}]. Using this model, T{sub R}, {alpha}{sub W}, and {eta}{sub CE} can be expressed in terms of quantities directly measurable in a hohlraum experiment. For a steady-state hohlraum that encloses a convex capsule, …

The objectives of this study were to verify the predictions of the Eppler Airfoil Design and Analysis Code for Reynolds numbers up to 6 x 106 and to acquire the section characteristics of two airfoils being considered for large, megawatt-size wind turbines. One airfoil, the S825, was designed to achieve a high maximum lift coefficient suitable for variable-speed machines. The other airfoil, the S827, was designed to achieve a low maximum lift coefficient suitable for stall-regulated machines. Both airfoils were tested in the NASA Langley Low-Turbulence Pressure Tunnel (LTPT) for smooth, fixed-transition, and rough surface conditions at Reynolds numbers of 1, 2, 3, 4, and 6 x 106. The results show the maximum lift coefficient of both airfoils is substantially underpredicted for Reynolds numbers over 3 x 106 and emphasized the difficulty of designing low-lift airfoils for high Reynolds numbers.

The Department of Energy has over 200 different fuel types which will be placed in a geologic repository for ultimate disposal. At the present time, DOE EM is responsible for assuring safe existing conditions, achieving interim storage, and preparing for final disposition. Each task is governed by regulations which dictate a certain degree of knowledge regarding the contents and condition of the fuel. This knowledge and other associated characteristics are referred to as data needs. It is the stance of DOE EM, that personnel and economic resources are not available to obtain the necessary data to characterize such individual fuel type for final disposal documentation purposes. In addition, it is beyond the need of DOE to do so. This report describes the effort to classify the 200+ fuel types into a subset of fuel types for the purpose of non-destructive analysis (NDA) measurement system development and demonstration testing in support of the DOE National Spent Nuclear Fuel (NSNFP) Program. The fuel types have been grouped into 37 groups based on fuel composition, fuel form, assembly size, enrichment, and other characteristics which affect NDA measurements (e.g., neutron poisons).

In the US, there are two sets of key decommissioning records clearly identified -- those that are essential for planning the D and D of a facility and then those that are the result of the decommissioning process itself. In some cases, the regulatory authorities require and in others advise the licensees of the records that may be useful or which are required to be kept from the decommissioning. In the remainder of the paper, the author attempts to highlight some important aspects of decommissioning recordkeeping.

Exploitation of certain niche markets for small wind turbines is one strategy that could help speed the commercialization of grid-connected small turbines. The authors review the world's turbine manufacturers, the utility grid-connected applications and selected niche markets for grid-connected small wind systems (0.1 to 100 kilowatts). Wind turbine installation and purchase are handled under three different payment scenarios: paid in full up front, paid through a second mortgage, or paid as part of a first mortgage. The authors used a simple payback method to compare these scenarios and analyze the costs and energy produced for three different U.S. small wind turbines. When there is a buy-down program for the small wind turbine combined with other financial factors such as net metering, tax exemptions, and tax credits, a strong market incentive is created for the use of grid-connected small wind turbines.

Several concepts (and assumptions) from the literature for porous metals and ceramics have been synthesized into a consistent model that predicts an admissibility limit on a material's porous yield surface. To ensure positive plastic work, the rate at which a yield surface can collapse as pores grow in tension must be constrained.