Publications

We show that Sorensen's [35] implicitly restarted Arnoldi method (including its block extension) is simultaneous iteration with an implicit projection step to accelerate convergence to the invariant subspace of interest. By using the geometric convergence theory for simultaneous iteration due to Watkins and Elsner [43], we prove that an implicitly restarted Arnoldi method can achieve a super-linear rate of convergence to the dominant invariant subspace of a matrix. Moreover, we show how an IRAM computes a nested sequence of approximations for the partial Schur decomposition associated with the dominant invariant subspace of a matrix.

Screening of sites for the potential application and reliance upon monitored natural attenuation (MNA) can be done using MNAtoolbox, a web-based tool for estimating extent of biodegradation, chemical transformation, and dilution. MNAtoolbox uses site-specific input data, where available (default parameters are taken from the literature), to roughly quantify the nature and extent of attenuation at a particular site. Use of MNAtoolbox provides 3 important elements of site evaluation: (1) Identifies likely attenuation pathways, (2) Clearly identifies sites where MNA is inappropriate, and (3) Evaluates data requirements for subsequent reliance on MNA as a sole or partial corrective action.

Sandia National Laboratories (SNL) and the Russian Federal Nuclear Center-All Russian Research Institute for Experimental Physics (VNIIEF)(also know as Arzamas-16) are collaborating on ways to assure the highest standards on safety, security, and international accountability of fissile material. This includes systems used to reduce the need for human access to fissile material, reduce radiation exposure, and provide prompt safety-related information, and provide continuous international accountability information while reducing the need for intrusive, on-site visits. This paper will report on the ongoing SNL/VNIIEF efforts to develop technologies and monitoring systems to meet these goals. Specific topics covered will include: the Smart Bolt tag/seal development, development and testing of electronic sensor platforms (U.S. T-1 ESP and VNIIEF Radio Tag) for monitoring and transportation applications, the ''Magazine-to-Magazine'' remote monitoring system field test, and the ''Facility-to-Facility'' storage monitoring system field trial.

Abstract not provided.

A new forcefield model was developed for the computer simulation of phosphate materials that have many important applications in the electronics and biomedical industries. The model provides a fundamental basis for the evaluation of phosphate glass structure and thermodynamics. Molecular dynamics simulations of a series of lithium phosphate glass compositions were performed using the forcefield model. A high concentration of three-membered rings (P{sub 3}O{sub 3}) occurs in the glass of intermediate composition (0.2 Li{sub 2}O {center_dot} 0.8P{sub 2}O{sub 5}) that corresponds to the minimum in the glass transition temperature curve for the compositional series. Molecular orbital calculations of various phosphate ring clusters indicate an increasing stabilization of the phosphate ring structure going from two- to four-membered rings.

A new approach is being pursued to study corrosion in Cu alloy systems by using combinatorial analysis combined with microscopic experimentation (the Combinatorial Microlab) to determine mechanisms for copper corrosion in air. Corrosion studies are inherently difficult because of complex interactions between materials and environment, forming a multidimensional phase space of corrosion variables. The Combinatorial Microlab was specifically developed to address the mechanism of Cu sulfidation, which is an important reliability issue for electronic components. This approach differs from convention by focusing on microscopic length scales, the relevant scale for corrosion. During accelerated aging, copper is exposed to a variety of corrosive environments containing sulfidizing species that cause corrosion. A matrix experiment was done to determine independent and synergistic effects of initial Cu oxide thickness and point defect density. The CuO{sub x} was controlled by oxidizing Cu in an electron cyclotron resonance (ECR) O{sub 2} plasma, and the point defect density was modified by Cu ion irradiation. The matrix was exposed to 600 ppb H{sub 2}S in 65% relative humidity air atmosphere. This combination revealed the importance of oxide quality in passivating Cu and prevention of the sulfidizing reaction. A native oxide and a defect-laden ECR oxide both react at 20 C to form a thick Cu{sub 2}S layer after exposure to H{sub 2}S, while different thicknesses of as-grown ECR oxide stop the formation of Cu{sub 2}S. The species present in the ECR oxide will be compared to that of an air oxide, and the sulfide layer growth rate will be presented.

We describe highly anisotropic reactive ion beam etching of nanophotonic structures in AlGaAs based on the ion beam divergence angle and chamber pressure. The divergence angle is shown to influence the shape of the upper portion of the etch while the chamber pressure controls the shape of the lower portion. This predictable region of parameter space resulted in highly anisotropic nanostructures. Deeply etched distributed Bragg reflectors are etched to an aspect ratio of 8:1 with 100 nm trench widths. The profile of the grating etch is straight with smooth sidewalls, flat bottoms, and squared corners. Two-dimensional photonic crystal post arrays are fabricated with smooth and vertical sidewalls, with structures as small as 180 nm in diameter and 2.0 {micro}m in height.

RF and mm-wave photonic devices and circuits have been developed at Sandia National Laboratories for applications ranging from RF optical data links to optical generation of mm-wave frequencies. This talk will explore recent high-speed photonics technology developments at Sandia including: (1) A monolithic optical integrated circuit for all-optical generation of mm-waves. Using integrated mode-locked diode lasers, amplifiers, and detectors, frequencies between 30 GHz and 90 GHz are generated by a single monolithic (Al,Ga)As optical circuit less than 2mm in its largest dimension. (2) Development of polarization-maintaining, low-insertion-loss, low v-pi, Mach-Zehnder interferometer (MZI) modulators with DC-to-potentially-K-band modulation bandwidth. New low-loss polarization-maintaining waveguide designs using binary alloys have been shown to reduce polarization crosstalk in undoped (Al,Ga)As waveguides, yielding high extinction ratio (>40dB) and low on-chip loss (<6dB) in Mach-Zehnder interferometers. RF drive voltage is reduced through use of 45rnrn-active length devices with modulator sensitivity, v-pi, less than 3V.

Recently, Morel and McGhee described an alternate second-order form of the transport equation called the self adjoint angular flux (SAAF) equation that has the angular flux as its unknown. The SAAF formulation has all the advantages of the traditional even- and odd-parity self-adjoint equations, with the added advantages that it yields the full angular flux when it is numerically solved, it is significantly easier to implement reflective and reflective-like boundary conditions, and in the appropriate form it can be solved in void regions. The SAAF equation has the disadvantage that the angular domain is the full unit sphere and, like the even- and odd- parity form, S{sub n} source iteration cannot be implemented using the standard sweeping algorithm. Also, problems arise in pure scattering media. Morel and McGhee demonstrated the efficacy of the SAAF formulation for neutral particle transport. Here we apply the SAAF formulation to coupled electron-photon transport problems using multigroup cross-sections from the CEPXS code and S{sub n} discretization.

The integration of miniaturized mechanical components has spawned a new technology known as microelectromechanical systems (MEMS). Surface micromachining, defined as the fabrication of micromechanical structures from deposited thin films, is one of the core technological processes underlying MEMS. Surface micromachined structures have a large ratio of surface area to volume which makes them particularly vulnerable to adhesion to the substrate or adjacent structures during release or in use--a problem is called stiction. Since microactuators can have surfaces in normal or sliding contact, function and wear are critical issues for reliable operation of MEMS devices. Surface modifications are needed to reduce adhesion and friction in micromechanical structures. In this paper, we will present a process used to selectively coat MEMS devices with Tungsten using a CVD (Chemical Vapor Deposition) process. We will discuss the effect of wet and vapor phase cleans along with different process variables. Endurance of the W coating is important, especially in applications where wear due to repetitive contacts with the film may occur. Further, tungsten is hard and chemically inert, Tungsten CVD is used in the integrated-circuit industry, which makes this, approach manufacturable.

Microfabrication technology has been applied to the development of a miniature, multi-channel gas phase chemical laboratory that provides fast response, small size, and enhanced versatility and chemical discrimination. Each analysis channel includes a sample concentrator followed by a gas chromatographic separator and a chemically selective surface acoustic wave detector array to achieve high sensitivity and selectivity. The performance of the components, individually and collectively, is described. The design and performance of novel micromachined acoustic wave devices, with the potential for improved chemical sensitivity, are also described.

The authors present prism coupling measurements on Al{sub x}Ga{sub 1{minus}x}As native oxides showing the dependence of refractive index on composition (0.3 {le} x {le} 0.97), oxidation temperature (400 {le} T {le} 500), and carrier gas purity. Index values range from n = 1.490 (x = 0.9, 400) to 1.707 (x = 0.3, 500 C). The oxides are shown to adsorb moisture, increasing their index by up to 0.10 (7%). Native oxides of Al{sub x}Ga{sub 1{minus}x}As (x {le} 0.5) have index values up to 0.27 higher and are less hygroscopic when prepared with a small amount of O{sub 2} in the N{sub 2} + H{sub 2}O process gas. The higher index values are attributed to a greater degree of oxidation of the Ga in the film.

In a quantum grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are on the one hand to create additional lateral electron confinement and on the other to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles.

Using Interracial Force Microscopy (IFM), we investigated the tribological behavior of hexadecanethiol monolayer on Au and films of octadecyltrichlorosilane (ODTS), perfluorodecyltrichlorosilane (PFTS) and dodecane on Si. We observe a strong correlation between hysteresis in a compression cycle (measured via nanoindentation) and friction. Additionally, we suggest that the amount of hysteresis and friction in each film is related to its detailed molecular structure, especially the degree of molecular packing.

The Geothermal Drilling Organization (GDO), founded in 1982 as a joint Department of Energy (DOE)-Industry organization, develops and funds near-term technology development projects for reducing geothermal drilling costs. Sandia National Laboratories administers DOE funds to assist industry critical cost-shared projects and provides development support for each project. GDO assistance to industry is vital in developing products and procedures to lower drilling costs, in part, because the geothermal industry is small and represents a limited market.

Energy (DOE)-industry research and development (R and D) organization, sponsors near-term technology development projects for reducing geothermal drilling and well maintenance costs. Sandia National Laboratories (Albuquerque, NM) administers DOE funds for GDO cost-shared projects and provides technical support. The GDO serves a very important function in fostering geothermal development. It encourages commercialization of emerging, cost-reducing drilling technologies, while fostering a spirit of cooperation among various segments of the geothermal industry. For Sandia, the GDO also serves as a means of identifying the geothermal industry's drilling fuel/or well maintenance problems, and provides an important forum for technology transfer. Successfully completed GDO projects include: the development of a high-temperature borehole televiewer, high-temperature rotating head rubbers, a retrievable whipstock, and a high-temperature/high-pressure valve-changing tool. Ongoing GDO projects include technology for stemming lost circulation; foam cement integrity log interpretation, insulated drill pipe, percussive mud hammers for geothermal drilling, a high-temperature/ high-pressure valve changing tool assembly (adding a milling capability), deformed casing remediation, high- temperature steering tools, diagnostic instrumentation for casing in geothermal wells, and elastomeric casing protectors.

The increased demand for portable electronics has lead to the need for higher performance and efficiency. Devices operating at less than 50 {micro}W of power are defined as ultra-low-power (ULP) devices. New progress has been achieved on InP/InGaAs HBT and InAIAs/InGaAs HBT optimized for ULP applications. f{sub T} values of 2.2 GHz, and f{sub MAX} values of 20 GHz have been obtained for HBTs operating at less than 40 {micro}W. Current gain is greater than 45 with the device operating at less than 20 {micro}A on a 2.5 x 5 {micro}m{sup 2} device. These devices have been significantly improved over the previously reported MOCVD grown InP/InGaAs ULP HBT which has f{sub MAX} of 10 GHz operating in the ultra-low-power level. The improvements have been attributed to the reduction of base dopant diffusion associated with Zn doping.

MTI is a comprehensive research and development project that includes up-front modeling and analysis, satellite system design, fabrication, assembly and testing, on-orbit operations, and experimentation and data analysis. The satellite is designed to collect radiometrically calibrated, medium resolution imagery in 15 spectral bands ranging from 0.45 to 10.70 pm. The payload portion of the satellite includes the imaging system components, associated electronics boxes, and payload support structure. The imaging system includes a three-mirror anastigmatic off-axis telescope, a single cryogenically cooled focal plane assembly, a mechanical cooler, and an onboard calibration system. Payload electronic subsystems include image digitizers, real-time image compressors, a solid state recorder, calibration source drivers, and cooler temperature and vibration controllers. The payload support structure mechanically integrates all payload components and provides a simple four point interface to the spacecraft bus. All payload components have been fabricated and tested, and integrated.

This project has comprised design, analysis, laboratory testing, and field testing of insulated drill pipe (IDP). This paper will briefly describe the earlier work, but will focus on results from the recently-completed field test in a geothermal well. Field test results are consistent with earlier analyses and laboratory tests, all of which support the conclusion that insulated drill pipe can have a very significant effect on circulating fluid temperatures. This will enable the use of downhole motors and steering tools in hot wells, and will reduce corrosion, deterioration of drilling fluids, and heat-induced failures in other downhole components.

GaN Schottky diodes were exposed to N₂ or H₂ Inductively Coupled Plasmas prior to deposition of the rectifying contact. Subsequent annealing, wet photochemical etching or (NH₄)₂S surface passivation treatments were examined for their effect on diode current- voltage characteristics. We found that either annealing at 750 °C under N₂, or removal of ~500-600 Å of the surface essentially restored the initial I-V characteristics. There was no measurable improvement in the plasma-exposed diode behavior with (NH₄)₂S treatments.

We analyze the transverse profiles of oxide-confined vertical cavity laser diodes as a function of aperture size. For small apertures we demonstrate that thermal lensing can be the dominant effect in determining the transverse resonator properties. We also analyze pattern formation in lasers with large apertures where we observe the appearance of tilted waves.

The goal of the Russian Navy Fuels Program is to incorporate nuclear fuel that is in the custody of the Russian Navy into a materials protection, control and accounting program. In addition to applying MPC and A upgrades to existing facilities, a program is underway to train site personnel in MPC and A activities. The goal is to assure that the upgraded facilities are managed, operated and maintained in an effective, sustainable manner. Training includes both the conceptual and necessary operational aspects of the systems and equipment. The project began with a Needs Assessment to identify priorities and objectives of required training. This led to the creation of a series of classes developed by Kurchatov Institute. One course was developed to allow attendees to get a general understanding of goals and objectives of nuclear MPC and A systems in the context of the Russian Navy. A follow-on course provided the detailed skills necessary for the performance of specialized duties. Parallel sessions with hands-on exercises provided the specific training needed for different personnel requirements. The courses were presented at KI facilities in Moscow. This paper reviews the work to date and future plans for this program.

Various efforts to map the structure of science have been undertaken over the years. Using a new tool, VxInsight{trademark}, we have mapped and displayed 3000 journals in the physical sciences. This map is navigable and interactively reveals the structure of science at many different levels. Science mapping studies are typically focused at either the macro-or micro-level. At a macro-level such studies seek to determine the basic structural units of science and their interrelationships. The majority of studies are performed at the discipline or specialty level, and seek to inform science policy and technical decision makers. Studies at both levels probe the dynamic nature of science, and the implications of the changes. A variety of databases and methods have been used for these studies. Primary among databases are the citation indices (SCI and SSCI) from the Institute for Scientific Information, which have gained widespread acceptance for bibliometric studies. Maps are most often based on computed similarities between journal articles (co-citation), keywords or topics (co-occurrence or co-classification), or journals (journal-journal citation counts). Once the similarity matrix is defined, algorithms are used to cluster the data.

Thermally-Induced Voltage Alteration (TIVA) and Seebeck Effect Imaging (SEI) are newly developed techniques for localizing shorted and open conductors from the front and backside of an IC. Recent improvements have greatly increased the sensitivity of the TIVA/SEI system, reduced the acquisition times by more than 20X, and localized previously unobserved defects. The system improvements, non-linear response of IC defects to heating, modeling of laser heating and examples using the improved system are presented.

Performance tests of a scaled passive autocatalytic recombine (PAR) were performed in the Surtsey test vessel at Sandia National Laboratories. Measured hydrogen depletion rate data were obtained and compared with previous work. Depletion rate is most likely proportional to PAR scale. PAR performance in steamy environments (with and without hydrophobic coating) was investigated. The tests determined that the PAR startup delay times decrease with increasing hydrogen concentrations in steamy environments. Tests with placement of the PAR near a wall (as opposed to a center location) yielded reduced depletion rates. Tests at low oxygen concentrations also showed a reduced recombination rate. The PAR repeatedly ignited hydrogen at about 6 mol% concentration with a catalyst temperature near 940 K. Velocity data at the PAR exhaust were used to calculate the volumetric flow rate through the PAR as a function of the vessel hydrogen concentration.

Multivariate techniques were used to address the quantification of {sup 17}O-NMR (nuclear magnetic resonance) spectra for a series of primary alcohol mixtures. Due to highly overlapping resonances, quantitative spectral evaluation using standard integration and deconvolution techniques proved difficult. Multivariate evaluation of the {sup 17}O-NMR spectral data obtained for 26 mixtures of five primary alcohols demonstrated that obtaining information about spectral overlap and interferences allowed the development of more accurate models. Initial partial least squares (PLS) models developed for the {sup 17}O-NMR data collected from the primary alcohol mixtures resulted in very poor precision, with signal overlap between the different chemical species suspected of being the primary contributor to the error. To directly evaluate the question of spectral overlap in these alcohol mixtures, net analyte signal (NAS) analyses were performed. The NAS results indicate that alcohols with similar chain lengths produced severely overlapping {sup 17}O-NMR resonances. Grouping the alcohols based on chain length allowed more accurate and robust calibration models to be developed.

This report describes an inert atmosphere enclosed gas-tungsten arc welding system which has been assembled in support of the MC2730, MC2730A and MC 3500 Radioisotope Thermoelectric Generator (RTG) Enhanced Surveillance Program. One goal of this program is to fabricate welds with microstructures and impurity levels which are similar to production heat source welds previously produced at Los Alamos National Laboratory and the Mound Facility. These welds will subsequently be used for high temperature creep testing as part of the overall component lifetime assessment. In order to maximize the utility of the welding system, means for local control of the arc atmosphere have been incorporated and a wide range of welding environments can easily be evaluated. The gas-tungsten arc welding system used in the assembly is computer controlled, includes two-axis and rotary motion, and can be operated in either continuous or pulsed modes. The system can therefore be used for detailed research studies of welding impurity effects, development of prototype weld schedules, or to mimic a significant range of production-like welding conditions. Fixturing for fabrication of high temperature creep test samples have been designed and constructed, and weld schedules for grip-tab and test welds have been developed. The microstructure of these welds have been evaluated and are consistent with those used during RTG production.

This report represents the completion of a 6 month Laboratory-Directed Research and Development (LDRD) program that focused on research and development of novel compound semiconductor, InGaAsN. This project seeks to rapidly assess the potential of InGaAsN for improved high-efficiency photovoltaic. Due to the short time scale, the project focused on quickly investigating the range of attainable compositions and bandgaps while identifying possible material limitations for photovoltaic devices. InGaAsN is a new semiconductor alloy system with the remarkable property that the inclusion of only 2% nitrogen reduces the bandgap by more than 30%. In order to help understand the physical origin of this extreme deviation from the typically observed nearly linear dependence of alloy properties on concentration, we have investigated the pressure dependence of the excited state energies using both experimental and theoretical methods. We report measurements of the low temperature photoluminescence energy of the material for pressures between ambient and 110 kbar. We describe a simple, density-functional-theory-based approach to calculating the pressure dependence of low lying excitation energies for low concentration alloys. The theoretically predicted pressure dependence of the bandgap is in excellent agreement with the experimental data. Based on the results of our calculations, we suggest an explanation for the strongly non-linear pressure dependence of the bandgap that, surprisingly, does not involve a nitrogen impurity band. Additionally, conduction-band mass measurements, measured by three different techniques, will be described and finally, the magnetoluminescence determined pressure coefficient for the conduction-band mass is measured. The design, growth by metal-organic chemical vapor deposition, and processing of an In{sub 0.07}Ga{sub 0.93}As{sub 0.98}N{sub 0.02} solar cell, with 1.0 eV bandgap, lattice matched to GaAs is described. The hole diffusion length in annealed, n-type InGaAsN is 0.6-0.8 pm, and solar cell internal quantum efficiencies >70% are obtained. Optical studies indicate that defects or impurities, from doping and nitrogen incorporation, limit cell performance.

Selective oxidation of AlGaAs compounds has facilitated dramatic improvements in the performance of near IR VCSELS. Under the auspices of this proposal we have: (1) expanded our understanding of both the strengths and the limitations of this technology; (2) explored its applicability to other Al bearing materials; (3) utilized this technology base to demonstrate a variety of new electronic and optoelectronic devices; and (4) established the reliability and manufacturability of oxidized devices such as VCSELS. Specifically, we have investigated conditions required to maximize control of the oxidation process as well as those required to facilitate inhibit etching of the resultant oxide. Concurrently, studies were performed to extend the technology to other Al-bearing compounds such as Al(Ga)AsSb, InAl(Ga)P and Al(Ga)N. Several new devices utilizing the selective oxidation technology of AlGaAs, as well as Al(Ga)AsSb were be considered. On a separate front, we also explored the possibility of using oxidized AlGaAs and InAl(Ga)P to form GaAs/AIGaAs FETs. Finally, reliability and manufacturability issues of the high performance VCSELS fabricated using selective oxidation technology, were addressed.

The series of tests described in this report are intended to simulate actual use and abuse conditions and internally initiated failures that may be experienced in electrochemical storage systems (ECSS). These tests were derived from Failure Mode and Effect Analysis, user input, and historical abuse testing. The tests are to provide a common framework for various ECSS technologies. The primary purpose of testing is to gather response information to external/internal inputs. Some tests and/or measurements may not be required for some ECSS technologies and designs if it is demonstrated that a test is not applicable, and the measurements yield no useful information.

The elevation change data measured at the Bryan Mound Strategic Petroleum Reserve (SPR) site over the last 16+ years has been studied and a model utilized to project elevation changes into the future. The subsidence rate at Bryan Mound is low in comparison with other Strategic Petroleum Reserve sites and has decreased with time due to the maintenance of higher operating pressures and the normal decrease in creep closure rate of caverns with time. However, the subsidence at the site is projected to continue. A model was developed to project subsidence values 20 years into the future; no subsidence related issues are apparent from these projections.

Fifteen aluminum honeycomb cubes (3 in.) have been crushed in the Mechanical Shock Laboratory's drop table testing machines. This report summarizes shock experiments with honeycomb densities of 22.1 pcf and 38.0 pcf and with crush weights of 45 lb, 168 lb, and 268 lb. The honeycomb samples were crushed in all three orientations, W, L, and T. Most of the experiments were conducted at an impact velocity of {approx}40 fps, but higher velocities of up to 90 fps were used for selected experiments. Where possible, multiple experiments were conducted for a specific orientation and density of the honeycomb samples. All results are for Hexcel honeycomb except for one experiment with Alcore honeycomb and have been evaluated for validity. This report contains the raw acceleration data measured on the top of the drop table carriage, pictures of the crushed samples, and normalized force-displacement curves for all fifteen experiments. These data are not strictly valid for material characteristics in L and T orientations because the cross-sectional area of the honeycomb changed (split) during the crush. However, these are the best data available at this time. These dynamic crush data do suggest a significant increase in crush strength to 8000 psi ({approximately} 25-30% increase) over quasi-static values of {approximately}6000 psi for the 38.0 pcf Hexcel Honeycomb in the T-orientation. An uncertainty analysis is included and estimates the error in these data.

The Zinc/Bromine Load-Leveling Battery Development contract (No. 40-8965) was partitioned at the outset into two phases of equal length. Phase 1 started in September 1990 and continued through December 1991. In Phase 1, zinc/bromine battery technology was to be advanced to the point that it would be clear that the technology was viable and would be an appropriate choice for electric utilities wishing to establish stationary energy-storage facilities. Criteria were established that addressed most of the concerns that had been observed in the previous development efforts. The performances of 8-cell and 100-cell laboratory batteries demonstrated that the criteria were met or exceeded. In Phase 2, 100-kWh batteries will be built and demonstrated, and a conceptual design for a load-leveling plant will be presented. At the same time, work will continue to identify improved assembly techniques and operating conditions. This report details the results of the efforts carried out in Phase 1. The highlights are: (1) Four 1-kWh stacks achieved over 100 cycles, One l-kWh stack achieved over 200 cycles, One 1-kWh stack achieved over 300 cycles; (2) Less than 10% degradation in performance occurred in the four stacks that achieved over 100 cycles; (3) The battery used for the zinc loading investigation exhibited virtually no loss in performance for loadings up to 130 mAh/cm{sup 2}; (4) Charge-current densities of 50 ma/cm{sup 2} have been achieved in minicells; (5) Fourteen consecutive no-strip cycles have been conducted on the stack with 300+ cycles; (6) A mass and energy balance spreadsheet that describes battery operation was completed; (7) Materials research has continued to provide improvements in the electrode, activation layer, and separator; and (8) A battery made of two 50-cell stacks (15 kWh) was produced and delivered to Sandia National Laboratories (SNL) for testing. The most critical development was the ability to assemble a battery stack that remained leak free. The task of sealing the battery stack using vibration welding has undergone significant improvement resulting in a viable production process. Through several design iterations, a solid technology base for larger battery stack designs was established. Internal stack stresses can now be modeled, in addition to fluid velocity and fluid pressure distribution, through the use of a finite element analysis computer program. Additionally, the Johnson Controls Battery Group, Inc. (JCBGI) proprietary FORTRAN model has been improved significantly, enabling accurate performance predictions. This modeling was used to improve the integrity and performance of the battery stacks, and should be instrumental in reducing the turnaround time from concept to assembly.

This report presents interpretations of hydraulic tests conducted in bedded evaporates of the Salado Formation from May 1992 through May 1995 at the Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico. The WIPP is a US Department of Energy research and development facility designed to demonstrate safe disposal of transuranic wastes from the nation's defense programs. The WIPP disposal horizon is located in the lower portion of the Permian Salado Formation. The hydraulic tests discussed in this report were performed in the WIPP underground facility by INTERA inc. (now Duke Engineering and Services, Inc.), Austin, Texas, following the Field Operations Plan and Addendum prepared by Saulnier (1988, 1991 ) under the technical direction of Sandia National Laboratories, Albuquerque, New Mexico.

Aging analyses were performed on solder joints from two radar units: (1) a laboratory, N57 tube-type radar unit and (2) a field-returned, B61-0, tube-type radar unit. The cumulative temperature environments experienced by the units during aging were calculated from the intermetallic compound layer thickness and the mean Pb-rich phase particle size metrics for solder joints in the units, assuming an aging time of 35 years for both radars. Baseline aging metrics were obtained from a laboratory test vehicle assembled at AS/FM and T; the aging kinetics of both metrics were calculated from isothermal aging experiments. The N57 radar unit interconnect board solder joints exhibited very little aging. The eyelet solder joints did show cracking that most likely occurred at the time of assembly. The eyelet, SA1126 connector solder joints, showed some delamination between the Cu pad and underlying laminate. The B61 field-returned radar solder joints showed a nominal degree of aging. Cracking of the eyelet solder joints was observed. The Pb-rich phase particle measurements indicated additional aging of the interconnects as a result of residual stresses. Cracking of the terminal pole connector, pin-to-pin solder joint was observed; but it was not believed to jeopardize the electrical functionality of the interconnect. Extending the stockpile lifetime of the B61 tube-type radar by an additional 20 years would not be impacted by the reliability of the solder joints with respect to further growth of the intermetallic compound layer. Additional coarsening of the Pb-rich phase will increase the joints' sensitivity to thermomechanical fatigue.

This report summarizes a public workshop that was held on April 27, 1999, in Rockville, Maryland. The workshop was conducted as part of the US Nuclear Regulatory Commission's (NRC) efforts to further develop its understanding of the risks associated with low power and shutdown operations at US nuclear power plants. A sufficient understanding of such risks is required to support decision-making for risk-informed regulation, in particular Regulatory Guide 1.174, and the development of a consensus standard. During the workshop the NRC staff discussed and requested feedback from the public (including representatives of the nuclear industry, state governments, consultants, private industry, and the media) on the risk associated with low-power and shutdown operations.

For a number of years, we have been initiating steam explosions of single drops of molten materials with pressure and flow (bubble growth) transients generated by discharging a capacitor bank through gold bridgewires placed underwater. Recent experimental and theoretical advances in the field of steam explosions, however, have made it important to substantially increase these relatively mild transients in water without using high explosives, if possible. To do this with the same capacitor bank, we have discharged similar energies through tiny strips of aluminum foil submerged in water. By replacing the gold wires with the aluminum strips, we were able to add the energy of the aluminum-water combustion to that normally deposited electrically by the bridgewire explosion in water. The chemical enhancement of the explosive characteristics of the discharges was substantial: when the same electrical energies were discharged through the aluminum strips, peak pressures increased as much as 12-fold and maximum bubble volumes as much as 5-fold above those generated with the gold wires. For given weights of aluminum, the magnitudes of both parameters appeared to exceed those produced by the underwater explosion of equivalent weights of high explosives.

A 2-D, lattice-Monte Carlo approach was developed to simulate ferroelectric domain structure. The model currently utilizes a Hamiltonian for the total energy based only upon electrostatic terms involving dipole-dipole interactions, local polarization gradients and the influence of applied electric fields. The impact of boundary conditions on the domain configurations obtained was also examined. In general, the model exhibits domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. The model was also extended to enable the simulation of ferroelectric hysteresis behavior. Simulated hysteresis loops were found to be very similar in appearance to those observed experimentally in actual materials. This qualitative agreement between the simulated hysteresis loop characteristics and real ferroelectric behavior was also confirmed in simulations run over a range of simulation temperatures and applied field frequencies.

Real-time measurements of island coarsening during SiGe/Si (001) deposition reveal unusual kinetics. In particular, the mean island volume increases superlinearly with time, while the areal density of islands decreases at a faster-than-linear rate. Neither observation is consistent with standard considerations of Ostvvald ripening. We attribute our observed kinetics to the effect of elastic interactions in the densely growing island array. Island coalescence likely plays an important role as well.

The effect of Inductively Coupled Plasma H{sub 2} or Ar discharges on the breakdown voltage of p-GaN diodes was measured over a range of ion energies and fluxes. The main effect of plasma exposure is a decrease in net acceptor concentration to depths of 400-550{angstrom}. At high ion fluxes or energies there can be type conversion of the initially p-GaN surface. Post etch annealing at 900 C restores the initial conductivity.

The field of microfluidics is undergoing rapid growth in terms of new device and system development. Among the many methods of fabricating microfluidic devices and systems, surface micromachining is relatively underrepresented due to difficulties in the introduction of fluids into the very small channels produced, packaging problems, and difficulties in device and system characterization. The potential advantages of using surface micromachining including compatibility with the existing integrated circuit tool set, integration of electronic sensing and actuation with microfluidics, and fluid volume minimization. In order to explore these potential advantages we have developed first generation surface micromachined microfluidic devices (channels) using an adapted pressure sensor fabrication process to produce silicon nitride channels, and the SUMMiT process to produce polysilicon channels. The channels were characterized by leak testing and flow rate vs. pressure measurements. The fabrication processes used and results of these tests are reported in this paper.

Very high current generators are being developed to drive compact loads leading to conductors carrying very high current densities. Losses in conductors include resistive, magnetic field diffusion, pdV work, and material motion contributions. We have designed and executed experiments on Sandia's 100-ns rise time, 20- MA Z accelerator to quantify those losses at current densities reaching 10 MA/cm. In these experiments we delivered nearly 20 MA to both high-current density and low-current density short circuit loads. We used B-dot probes and VISAR techniques to measure the magnetic field near the load. A reduction in the delivered current of ~ 15% over the 20-MA peak current prediction made without resistive losses was observed. Comparisons of these data with radiation magneto-hydrodynamics codes (RMHD) will be presented. Implications on the efficiency of next generation pulsed power drivers will be discussed.

We have demonstrated successful operation of a 3.35- m-diameter insulator stack at 158 kV/cm on five consecutive Z-accelerator shots. The stack consisted of five +45°-profile 5.715-cm-thick cross-linked-polystyrene (Rexolite- 1422) insulator rings, and four anodized- aluminum grading rings shaped to reduce the field at cathode triple junctions. The width of the voltage pulse at 89% of peak was 32 ns. We compare this result to a new empirical flashover relation developed from previous small-insulator experiments conducted with flat unanodized electrodes. The relation predicts a 50% flashover probability for a Rexolite insulator during an applied voltage pulse when E_maxe^-0.27/d(t_effC)^1/10 = 224, where E_max is the peak mean electric field (kV/cm), d is the insulator thickness (cm), t_eff is the effective pulse width (ps), and C is the insulator circumference (cm). We find the Z stack can be operated at a stress at least 19% higher than predicted. This result, and previous experiments conducted by Vogtlin, suggest anodized electrodes with geometries that reduce the field at both anode and cathode triple junctions would improve the flashover strength of +45° insulators.

In August of 1998 the Z facility leaked approximately 150 gallons of deionized water into the dielectric oil of the Energy Storage Section (ESS). After processing the oil to remove existing particulate and free water the dielectric breakdown strength increased from the mid 20kV range to values in excess of 40 kV. 40 kV is above historical operating levels of about 35 kV. This, however, was not enough to allow 90 kV charging of the Marx Generators in the ESS. Further analysis of the oil showed dissolved water at a saturated level (70 - 80 ppm) and some residual particulate contamination smaller than 3 microns. The dissolved water and particulate combination was preventing the 90 kV charging of the Marx Generators in the ESS. After consulting with the oil industry it was determined that nitrogen sparging could be used to remove the dissolved water. Further particulate filtering was also conducted. After approximately 20 hours of sparging the water content in the ESS was reduced to 42 ppm which enabled Marx charging to 90 kV.

Fischer-Tropsch synthesis was discovered in Germany in the 1920's and has been studied by every generation since that time. As technology and chemistry, in general, improved through the decades, new insights, catalysts, and technologies were added to the Fischer-Tropsch process, improving it and making it more economical with each advancement. Opportunities for improving the Fischer-Tropsch process and making it more economical still exist. This paper gives an overview of the present Fischer-Tropsch processes and offers suggestions for areas where a research investment could improve those processes. Gas-to-liquid technology, which utilizes the Fischer Tropsch process, consists of three principal steps: Production of synthesis gas (hydrogen and carbon monoxide) from natural gas, the production of liquid fuels from syngas using a Fischer-Tropsch process, and upgrading of Fischer-Tropsch fuels. Each step will be studied for opportunities for improvement and areas that are not likely to reap significant benefits without significant investment.

Spatially Interpolated Nonlinear Anodization in Synthetic Aperture Original formulation of spatially variant anodization for complex synthetic aperture radar (SAR) imagery oversampled at twice the Nyquist rate (2.OX). Here we report a spatially interpolating, noninteger-oversampled SVA sidelobe. The pixel's apparent IPR location is assessed by comparing its value to the sum of its value plus weighted comparable for exact interpolation. However, exact interpolation implies an ideal sine interpolator3 and large components may not be necessary. Note that P is the summation of IPR diagonal values. The value of a sine IPR on the diagonals is a sine-squared; values much less than cardinal direction (m, n) values. This implies that cardinal direction interpolation requires higher precision than diagonal interpolation. Consequently, we employed a smaller set. The spatially interpolated SVA used an 8-point/4-point sine interpolator described above. Table 1 shows the Table 1 results show a two-times speed-up using the 1.3x oversampled and spatially interpolated SVA over the Figure 1d. Detected results of 1.3x oversampled sine interpolated spatially variant

Floating body effects can undermine the soft-error tolerance of partially-depleted SOI technologies [1, 2]. Body ties are used to mitigate floating body effects [3,4]. In this paper, we study the charge collection properties and effectiveness of different body tie designs for reducing soft errors induced by energetic particle strikes.

It is well established that pulsed power technology is relatively cheaper than other architectures aiming to produce high-current, high-voltage electron or ion accelerators. The footprints of most pulsed power accelerators are large making them incompatible for applications that require either portability or a large number of similar components for very high power devices (like Z-pinch accelerators). Most of the modern pulsed power accelerators require several stages of pulse conditioning (pulse forming) to convert the multimicrosecond pulse of a Marx generator output to the 50-1 00-ns pulse required for an electron or ion diode or a cell cavity of an inductive voltage adder We propose a new and unique method for constmcting high-current, high-voltage pulsed accelerators. The salient future of the approach is switching and inductively adding the pulses at low voltage straight out of the capacitors through low inductance transfer and soft iron core isolation. High currents can be achieved by feeding each core with many capacitors connected in parallel in a circular array. High voltage is obtained by inductively adding many stages in series. Utilizing the presently available capacitors and switches we can build a 300-kA, 7-MV generator with an overall outer diameter (including capacitors and switches) of 1.2 m and length of 6.5 m! In addition our accelerator can be multipulsed with a repetition rate up to the capacitor specifications and no less than 10 Hz. As an example the design of a 3-MeV, 100-kA accelerator is presented and analyzed.

Abstract not provided.

Abstract not provided.