The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

The goal of the Fermilab High Field Magnet (HFM) R and D project is to explore various designs and production technology of a high-field, low-cost Nb{sub 3}Sn accelerator magnet suitable for a future Very Large Hadron Collider (VLHC). The model under fabrication consists of two-layer shell-type coil with 43.5 mm aperture and cold iron yoke. Fermilab concept of magnet design and fabrication technology involves some specific features such as curing of half-coil with ceramic binder/matrix before reaction, and then simultaneous reaction and impregnation of both half-coils to get a coil pipe structure. The coil pipe is mechanically supported by the vertically-split iron yoke locked by two aluminum clamps and a thick stainless steel skin. 2D finite element analysis has been performed to study and optimize the prestress in the coil and in the structural elements at room temperature and at 4.2 K. Model description, material properties and the results of mechanical analysis are reported in this paper.

Fermilab, in collaboration with LBNL, is exploring the use of the react and wind technique for a common coil dipole with a Nb{sub 3}Sn Rutherford cable. An R and D program on conductor design and magnet technology was begun aiming at an 11 T, 2 layer, 30 mm aperture design operating at 4.5 K. The goal is to explore the feasibility of the react and wind technique for flat coils with a minimum bending radius of 90 mm. In order to improve the understanding of the I{sub c} degradation caused by bending after reaction this effect will be studied on both strands and cables. In this paper, the authors present two techniques to measure the critical current degradation due to bending, both in wires and cables, using standard test facilities. Together with the description of the program they show the results of the first measurements on strands and the layout of the cables that are being produced.

A new method for the solution of the unsteady Euler equations has been developed. The method combines staggered grid Lagrangian techniques with structured local adaptive mesh refinement (AMR). This method is a precursor to a more general adaptive arbitrary Lagrangian Eulerian (ALE-AMR) algorithm under development, which will facilitate the solution of problems currently at and beyond the boundary of soluble problems by traditional ALE methods by focusing computational resources where they are required. Many of the core issues involved in the development of the ALE-AMR method hinge upon the integration of AMR with a Lagrange step, which is the focus of the work described here. The novel components of the method are mainly driven by the need to reconcile traditional AMR techniques, which are typically employed on stationary meshes with cell-centered quantities, with the staggered grids and grid motion employed by Lagrangian methods. These new algorithmic components are first developed in one dimension and are then generalized to two dimensions. Solutions of several model problems involving shock hydrodynamics are presented and discussed.

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Sandia National Laboratories has been studying Energy Storage Systems since the late 1970s. Sandia started by applying their defense program battery experience to larger stationary systems, eventually joining in the formation of the Utility Battery Group which has since evolved into the Energy Storage Association. Sandia's role, as a Department of Energy funded program is to look ahead at emerging technologies, perform early R and D and identify applications for Energy Storage Systems that offer significant benefit to the nation's electricity providers and users. In order to identify applications of energy storage, a two-phase Opportunities Analysis was conceptualized in FY94. Phase 1 of the project was completed and published in 1995 (SAND94-2605). Phase 2 of the project is an extension of Phase 1 to reexamine the identified applications in the dynamic environment of today. In a preliminary assessment of national benefits, SNL estimated that generation and transmission applications of storage could represent $17.2B in national benefits. In Phase 1 of the Opportunities Analysis, the T and D benefits were found to be significantly higher than previous estimates Phase 2 of the study, which began in late 1998, includes a refinement of the technical and economic understanding of the role of …

A flywheel is an electromechanical storage system in which energy is stored in the kinetic energy of a rotating mass. Flywheel systems under development include those with steel flywheel rotors and resin/glass or resin/carbon-fiber composite rotors. The mechanics of energy storage in a flywheel system are common to both steel- and composite-rotor flywheels. In both systems, the momentum of the rotating rotor stores energy. The rotor contains a motor/generator that converts energy between electrical and mechanical forms. In both types of systems, the rotor operates in a vacuum and spins on bearings to reduce friction and increase efficiency. Steel-rotor systems rely mostly on the mass of the rotor to store energy while composite flywheels rely mostly on speed. During charging, an electric current flows through the motor increasing the speed of the flywheel. During discharge, the generator produces current flow out of the system slowing the wheel down. The basic characteristics of a Flywheel system are shown. Steel flywheel systems are currently being marketed in the US and Germany and can be connected in parallel to provide greater power if required. Sizes range from 40kW to 1.6MW for times of 5--120 seconds. At this time sales are limited but growing. …

Welding plays an important role in the economical reuse and reclamation of used and failed nickel base superalloy blades. Previous research on microstructure development during laser beam welding of a single crystal CMSX4 alloy [Ref. l] showed non-equilibrium y/y{prime} microstructure development. In addition, the y{prime} precipitates were found to be irregular in shape and atom probe field ion microscopy illustrated the presence of diffusional concentration profile within the y phase in the as welded condition. To understand the above microstructure characteristics, y{prime} precipitation from y phase was investigated during continuous cooling from solutionizing temperature.

Based on prior work at the Lawrence Livermore National Laboratory ambient-temperature passive magnetic bearings are being adapted for use in high-power flywheel energy storage systems developed at the Trinity Flywheel Power company. En route to this goal specialized test stands have been built and computer codes have been written to aid in the development of the component parts of these bearing systems. The Livermore passive magnetic bearing system involves three types of elements, as follows: (1) Axially symmetric levitation elements, energized by permanent magnets., (2) electrodynamic ''stabilizers'' employing axially symmetric arrays of permanent magnet bars (''Halbach arrays'') on the rotating system, interacting with specially wound electrically shorted stator circuits, and, (3) eddy-current-type vibration dampers, employing axially symmetric rotating pole assemblies interacting with stationary metallic discs. The theory of the Livermore passive magnetic bearing concept describes specific quantitative stability criteria. The satisfaction of these criteria will insure that, when rotating above a low critical speed, a bearing system made up of the three elements described above will be dynamically stable. That is, it will not only be stable for small displacements from equilibrium (''Earnshaw-stable''), but will also be stable against whirl-type instabilities of the types that can arise from displacement-dependent drag …

Understanding the exchanges of carbon between the atmosphere and ocean and the fate of carbon delivered to the deep sea is fundamental to the evaluation of ocean carbon sequestration options. An additional key requirement is that sequestration must be verifiable and that environmental effects be monitored and minimized. These needs can be addressed by carbon system observations made from low-cost autonomous ocean-profiling floats and gliders. We have developed a prototype ocean carbon system profiler based on the Sounding Oceanographic Lagrangian Observer (SOLO; Davis et al., 1999). The SOLO/ carbon profiler will measure the two biomass components of the carbon system and their relationship to physical variables, such as upper ocean stratification and mixing. The autonomous observations within the upper 1500 m will be made on daily time scales for periods of months to seasons and will be carried out in biologically dynamic locations in the world's oceans that are difficult to access with ships (due to weather) or observe using remote sensing satellites (due to cloud cover). Such an observational capability not only will serve an important role in carbon sequestration research but will provide key observations of the global ocean's natural carbon cycle.

The Gamma-Ray multi-group analysis code MGA developed at Lawrence Livermore National Laboratory has been widely used in the area of gamma-ray non-destructive plutonium assay. This plutonium isotopic analysis code de-convolutes the complicated, 100-keV x-ray and gamma-ray region to obtain the ratio of Pu isotopes. Calibration of the detector efficiency is not required, but is determined intrinsically from the measured spectra. The code can either analyze low-energy gamma-ray spectrum taken using a high-resolution HPGe detector for energies below 300 keV, or analyze the low-energy spectrum combined with a high-energy spectrum (up to 1 MeV) in the two-detector analysis mode. In the latter case, the use of two detectors has been mandated by the conflicting requirements: excellent resolution at low energies (characteristic of small planar detectors) with good high-energy efficiency (characteristic of coaxial detectors). Usually, a high-energy spectrum taken using a coaxial Ge detector will not provide sufficient energy resolution for 100-keV plutonium isotopic analysis, while the small planar used at low energies has inadequate high-energy efficiency. An optimized-geometry ORTEC HPGe detector has been developed which combines good energy resolution at 100 keV combined with acceptable high-energy ({approx} 1 MeV) efficiency in a single detector. It has been used to gather spectra …

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Vertical cavity surface emitting lasers (VCSELs) which operate in multiple transverse optical modes have been rapidly adopted into present data communication applications which rely on multi-mode optical fiber. However, operation only in the fundamental mode is required for free space interconnects and numerous other emerging VCSEL applications. Two device design strategies for obtaining single mode lasing in VCSELs based on mode selective loss or mode selective gain are reviewed and compared. Mode discrimination is attained with the use of a thick tapered oxide aperture positioned at a longitudinal field null. Mode selective gain is achieved by defining a gain aperture within the VCSEL active region to preferentially support the fundamental mode. VCSELs which exhibit greater than 3 mW of single mode output power at 850 nm with mode suppression ratio greater than 30 dB are reported.

An international round robin study was conducted on the absorption measurement of laser-quality coatings. Sets of optically coated samples were made by a ''reactive DC magnetron'' sputtering and an ion beam sputtering deposition process. The sample set included a high reflector at 514 nm and a high reflector for the near infrared (1030 to 1318 nm), single layers of silicon dioxide, tantalum pentoxide, and hafnium dioxide. For calibration purposes, a sample metalized with hafnium and an uncoated, superpolished fused silica substrate were also included. The set was sent to laboratory groups for absorptance measurement of these coatings. Whenever possible, each group was to measure a common, central area and another area specifically assigned to the respective group. Specific test protocols were also suggested in regards to the laser exposure time, power density, and surface preparation.

Traceability to national or international standards is clearly required by commercial sector standards including ISO 9001:1994 (Ref. 1), ISO/IEC Guide 25 (Ref. 2), and the US equivalent of ISO/IEC Guide 25-ANSI/NCSL Z540-2-1997 (Ref. 3). In the draft replacement to ISO/IEC Guide 25-ISO 17025; measurements, not just equipment, must be traceable to SI units or reference to a natural constant. The implications of traceability to the US gear industry are significant. In order to meet the standards, either gear manufacturers must have calibrated artifacts or must establish their own traceability to SI units.

Several types of carbonaceous materials from Superior Graphite Co. were investigated for lithium ion intercalation. These commercially available cokes, graphitized cokes and graphites have a wide range of physical and chemical properties. The coke materials were investigated in propylene carbonate based electrolytes and the graphitic materials were studied in ethylene carbonate/dimethyl solutions to prevent exfoliation. The reversible capacities of disordered cokes are below 230 mAh/g and those for many highly ordered synthetic (artificial) and natural graphites approached 372 mAh/g (LiC{sub 6}). The irreversible capacity losses vary between 15 to as much as 200% of reversible capacities for various types of carbon. Heat treated cokes with the average particle size of 10 microns showed marked improvements in reversible capacity for lithium intercalation. The electrochemical characteristics are correlated with data obtained from scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET surface area analysis. The electrochemical performance, availability, cost and manufacturability of these commercial carbons will be discussed.

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This paper reports on the development of a unified one-equation model for the prediction of transitional and turbulent flows. An eddy viscosity - transport equation for non-turbulent fluctuation growth based on that proposed by Warren and Hassan (Journal of Aircraft, Vol. 35, No. 5) is combined with the Spalart-Allmaras one-equation model for turbulent fluctuation growth. Blending of the two equations is accomplished through a multidimensional intermittence function based on the work of Dhawan and Narasimha (Journal of Fluid Mechanics, Vol. 3, No. 4). The model predicts both the onset and extent of transition. Low-speed test cases include transitional flow over a flat plate, a single element airfoil, and a multi-element airfoil in landing configuration. High-speed test cases include transitional Mach 3.5 flow over a 5{degree} cone and Mach 6 flow over a flared-cone configuration. Results are compared with experimental data, and the spatial accuracy of selected predictions is analyzed.

In this paper we have shown how the direction cosine method of stripmap-mode IFSAR maybe modified for use in the spotlight-mode case. Spotlight-mode IFSAR geometry dictates a common aperture phase center, velocity vector, and baseline vector for every pixel in an image. Angle with respect to the velocity vector is the same for every pixel in a given column and can be computed from the column index, the Doppler of the motion compensation point and the Doppler column sample spacing used in image formation. With these modifications, the direction cosines and length of the line of sight vector to every scatterer in the scene may be computed directly from the raw radar measurements of range, Doppler, and interferometric phase.

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Melt-infiltrated ceramic matrix composite SiC/SiC material systems are under development for use in combustor liners for low-emission advanced gas turbines. Uncertainty in repeatability of processing methods for these large components (33--76 cm diameter), and hence possible reduced reliability for the end user. This requires that appropriate test methods, at both meso- and micro-scale, be used to ensure that the liners are acceptable for use. Nondestructive evaluation (NDE) methods, if demonstrated to reliably detect changes caused by processing, would be of significant benefit to both manufacturer and end user. This paper describes the NDE methods and their applications in detecting a process upset in a melt-infiltrated 33 cm combustor liner and how high-resolution scanning electron microscopy was used to verify the NDE data.

The authors present recent results from CDF and D0 on W and Z production cross sections, the width of the W boson, {tau}-e universality in W decays, trilinear gauge boson couplings, and on the observation of Z {r{underscore}arrow} b{anti b}.

In this paper, the authors present the friction and wear properties of nanocrystalline diamond (NCD) films grown in A-fullerene (C{sub 60}) and Ar-CH{sub 4} microwave plasmas. Specifically, they address the fundamental tribological issues posed by these films during sliding against Si{sub 3}N{sub 4} counterfaces in ambient air and inert gases. Grain sizes of the films grown by the new method are very small (10--30 nm) and are much smoother (20-40 nm, root mean square) than those of films grown by the conventional H{sub 2}-CH{sub 4} microwave-assisted chemical-vapor-deposition (CVD) process. Transmission electron microscopy (TEM) revealed that the grain boundaries of these films are very sharp and free of nondiamond phases. The microcrystalline diamond (MCD) films grown by most conventional methods consist of large grains and a rough surface finish, which can cause severe abrasion during sliding against other materials. The friction coefficients of films grown by the new method (i.e., in Ar-C{sub 60} and Ar-CH{sub 4} plasmas) are comparable to those of natural diamond, and wear damage on counterface materials is minimal. Fundamental tribological studies indicate that these films may undergo phase transformation during long-duration, high-speed and/or high-load sliding tests and that the transformation products trapped at the sliding interfaces can …

The Geothermal Research Department at Sandia National Laboratories, in collaboration with Drill Cool Systems, Inc., has worked to develop and test insulated drillpipe (IDP). IDP will allow much cooler drilling fluid to reach the bottom of the hole, making possible the use of downhole motors, electronics, and steering tools that are now unusable in high-temperature formations. Other advantages of cooler fluid include reduced degradation of drilling fluid, longer bit life, and reduced corrosion rates. The paper describes the theoretical background, laboratory testing, and field testing of IDP. Structural and thermal laboratory testing procedures and results are described. Results are given for a field test in a geothermal well, in which circulating temperatures in IDP are compared with those in conventional drillpipe (CDP) at different flow rates. A brief description of the software used to model wellbore temperature and to calculate sensitivity to IDP design differences is included, along with a comparison of calculated and measured wellbore temperatures in the field test. Analysis of mixed (IDP and CDP) drill strings and discussion of where IDP should be placed in a mixed string are presented.