The Chemical Waste Landfill (CWL) at Sandia National Laboratories/New Mexico (SNL/NM) is a 1.9-acre disposal site that was used for the disposal of chemical wastes generated by many of SNL/NM research laboratories from 1962 until 1985. These laboratories were primarily involved in the design, research and development of non-nuclear components of nuclear weapons and the waste generated by these labs included small quantities of a wide assortment of chemical products. A Resource Conservation and Recovery Act (RCRA) Closure Plan for the Chemical Waste Landfill was approved by the New Mexico Environment Department (NMED) in 1992. Subsequent site characterization activities identified the presence of significant amounts of chromium in the soil as far as 80 feet below ground surface (fbgs) and the delineation of a solvent plume in the vadose zone that extends to groundwater approximately 500 fbgs. Trichloroethylene (TCE) was detected in some groundwater samples at concentrations slightly above the drinking water limit of 5 parts per billion. In 1997 an active vapor extraction system reduced the size of the TCE vapor plume and for the last six quarterly sampling events groundwater samples have not detected TCE above the drinking water standard. A source term removal, being conducted as a Voluntary Corrective Measure (VCM), began in September 1998 and is expected to take up to two years. Four distinct disposal areas were identified from historical data and the contents of disposal pits and trenches in these areas, in addition to much of the highly contaminated soil surrounding the disposal cells, are currently being excavated. Buried waste and debris are expected to extend to a depth of 12 to 15 fbgs. Excavation will focus on the removal of buried debris and contaminated soil in a sequential, area by area manner and will proceed to whatever depth is required in order to remove all pit contents. Up to 50,000 cubic yards of soil and debris will be removed and managed during the excavation of the CWL. As part of the excavation process, soil is being separated from the buried debris using a 2-inch mechanical screen. After separation from the soil, debris items are further-segregated by matrix into the following categories: wood, scrap metal, concrete/aggregates, resins, compatible debris, intact chemical containers, radioactive and mixed waste, and high hazard items. One of the greatest sources of hazards throughout the excavation process is the removal of numerous intact chemical containers with unknown contents. A large portion of the excavated soil is contaminated with metals and/or solvents, Polychlorinated biphenyls (PCBs) are also known to be present. Most of the contaminated soils being excavated will be taken to the nearby Corrective Action Management Unit (CAMU) for treatment and management while a majority of the containers will be taken to the Hazardous Waste Management Facility or the Radioactive and Mixed Waste Management Facility for proper treatment and/or disposal at permitted offsite facilities.
A cryogenic, {beta}-layered NIF ignition capsule with a beryllium ablator that employs a BeO dopant (2% O) for opacity control is described. The design has an optimized yield of 12 MJ and uses a ''reduced drive'' hohlraum temperature pulse shape that peaks at {approx}250 eV. Shock timing sensitivity calculations have been performed for this capsule design. Individual uncertainties of (1) {approx}200 ps in the timing of the ''footpulse; (2) {approx}5% in the x-ray flux of the foot pulse and first step; (3) {approx}10% in the ablator EOS; or (4) {approx} 5 {micro}m in the DT ice layer thickness each have a significant impact on thermonuclear yield. Combined uncertainties have greater impact than isolated, individual issues. For example, a combination of uncertainties of: 200 ps in the foot + 2 eV in the foot + 5 pm in the DT thickness results in a calculation that produces only {approx}1% of the original design yield. A second, more speculative, capsule concept utilizing a liquid DT ablator is also discussed. This design produces a 5 MJ yield in a 250 eV peak drive calculation.
Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.
This paper reports on significant advances in electrothermal bent beam actuators. Designs for long throw linear and rotary actuators are described. Silicon p++ devices showed 20--30 {mu}m displacements with 150 {micro}N loads at actuation levels of 6--8 V, and 250--300 mW. An electroplated version provided 15 {mu}m displacements at 0.8 V and 450 mW. Inchworm type devices are reported that had linear displacements of 100 {micro}m with 200 {micro}N loads. Refinements in the modeling to account for non-linear thermal expansion coefficients and buckling are also reported.
Controlled impact methodology has been used on a powdergun to obtain dynamic behavior properties of Tributyl Phosphate (TBP). A novel test methodology is used to provide extremely accurate equation of state data of the liquid. A thin aluminum plate used for confining the liquid also serves as a diagnostic to provide reshock states and subsequent release adiabats from the reshocked state. Polar polymer, polyvinylidene fluoride (PVDF) gauges and velocity interferometer system for any reflector (VISAR) provided redundant and precise data of temporal resolution to five nanoseconds and shock velocity measurements of better than 1%. The design and test methodologies are presented in this paper.
We report a novel sol-gel dip-coating process to form dual-layer microporous silica membranes with improved membrane performance and reproducibility. First, we deposit a surfactant-templated silica (STS) intermediate layer on top of a commercial {gamma}-alumina support both to improve its ''surface finish'' and to prevent a subsequently deposited microporous overlayer from penetrating into the support. Second, membranes are processed under clean room conditions to avoid dust contamination and, third, membranes are vacuum-calcined to promote further pore shrinkage and impart surface hydrophobicity. The resulting asymmetric membrane exhibits a gradual change in pore diameter from 50{angstrom} ({gamma}-alumina support layer) to 10-12{angstrom} (STS intermediate layer), and then to 3-4{angstrom} (30nm thick, ultramicroporous silica top-layer). Compared to a single-layer process using only the microporous overlayer, the dual-layer process improves both flux and selectivity. For the industrially important problem of natural gas purification, the combined CO{sub 2} flux [(3{approx} 0.5) x 10{sup {minus}4} cm{sup 3}(STP)/(s{center_dot}cm{sup 2}{center_dot}cm-Hg)] and CO{sub 2}/CH{sub 4} separation factors [200{approx}600] are superior to all previously reported values for separation of a 50/50 (v/v) CO{sub 2}/CH{sub 4} gas mixture. In addition, the membrane selectively separated hydrogen from a simulated reformate from partial oxidation of methanol as evidenced by a high concentration of hydrogen recovery.
{sup 13}C-enriched polyethylene was subjected to {gamma}-irradiation in the presence of air at 25 and 80 C for total doses ranging from 71 to 355 kGy. Significant quantities of hydroperoxides were detected in the 25 C irradiated sample by {sup 13}C magic angle spinning NMR spectroscopy. This method of detection was performed on the solid polymer and required no chemical derivatization or addition of solvent. The chemical stability and subsequent products of the hydroperoxide species were studied by annealing the irradiated samples in air at temperatures ranging from 22 to 110 C. A time-temperature superposition analysis provided an activation energy of 108 kJ/mol for the hydroperoxide decomposition process. The primary products of hydroperoxide decomposition were ketones and secondary alcohols with lesser amounts of acids and esters. EPR measurements suggest that the reactive hydroperoxide species reside in the amorphous phase of polyethylene, consistent with degradation occurring in the amorphous phase.
Structure within thin epoxy films is investigated by neutron reflectivity (NR) as a function of resin/cross-linker composition and cure temperature. Variation in the cross-link density normal to the substrate surface is examined by swelling the films with the good solvent d-nitrobenzene (d-NB). The principal observation is a large excess of d-NB near the air surface. This is not a wetting layer, but rather indicates a lower cross-link density in the near-surface region. This effect is due to preferential segregation of the cross-linker to the air surface, driven by the lower surface tension of the cross-linker relative to the epoxide oligomers. The magnitude of the effect is a function of composition and cure temperature. Exclusion of d-NB from the region immediately adjacent to the substrate surface is also observed, possibly indicating a tightly bound layer of epoxy. Regarding swelling in the bulk of the films, the behavior is nonsymmetric with departure from the stoichiometric ratio. The films deficient in curing agent show greater equilibrium swelling and faster swelling kinetics than the films with an excess of curing agent.
The concept of building extremely small satellites which, either independently or as a collective, can perform missions which are comparable to their much larger cousins, has fascinated scientists and engineers for several years now. In addition to the now commonplace microelectronic integrated circuits, the more recent advent of technologies such as photonic integrated circuits (PIC's) and micro-electromechanical systems (MEMS) have placed such a goal within their grasp. Key to the acceptance of this technology will be the ability to manufacture these very small satellites in quantity without sacrificing their performance or versatility. In support of its nuclear treaty verification, proliferation monitoring and other remote sensing missions, Sandia National laboratories has had a 35-year history of providing highly capable systems, densely packaged for unintrusive piggyback missions on government satellites. As monitoring requirements have become more challenging and remote sensing technologies become more sophisticated, packaging greater capability into these systems has become a requirement. Likewise, dwindling budgets are pushing satellite programs toward smaller and smaller platforms, reinforcing the need for smaller, cheaper satellite systems. In the next step of its miniaturization plan, Sandia has begun development of technologies for a highly integrated miniature satellite. The focus of this development is to achieve nanosat or smaller dimensions while maintaining significant capability utilizing semiconductor wafer-level integration and, at the same time promoting affordability through modular generic construction.
A technique has been developed for producing calibrated metal hydride films for use in the measurement of high-energy (5--15 MeV) particle reaction cross sections for hydrogen and helium isotopes on hydrogen isotopes. Absolute concentrations of various hydrogen isotopes in the film is expected to be determined to better than {+-}2% leading to the capacity of accurately measuring various reaction cross sections. Hydrogen isotope concentrations from near 100% to 5% can be made accurately and reproducibly. This is accomplished with the use of high accuracy pressure measurements coupled with high accuracy mass spectrometric measurements of each constituent partial pressure of the gas mixture during loading of the metal occluder films. Various techniques are used to verify the amount of metal present as well as the amount of hydrogen isotopes; high energy ion scattering analysis, PV measurements before, during and after loading, and thermal desorption/mass spectrometry measurements. The most appropriate metal to use for the occluder film appears to be titanium but other occluder metals are also being considered. Calibrated gas ratio samples, previously prepared, are used for the loading gas. Deviations from this calibrated gas ratio are measured using mass spectrometry during and after the loading process thereby determining the loading of the various hydrogen isotopes. These techniques are discussed and pertinent issues presented.
Many aerospace structures must survive severe high frequency, hypersonic, random vibration during their flights. The random vibrations are generated by the turbulent boundary layer developed along the exterior of the structures during flight. These environments have not been simulated very well in the past using a fixed-based, single exciter input with an upper frequency range of 2 kHz. This study investigates the possibility of using acoustic ardor independently controlled multiple exciters to more accurately simulate hypersonic flight vibration. The test configuration, equipment, and methodology are described. Comparisons with actual flight measurements and previous single exciter simulations are also presented.
This study examines adhesion between silane-coated micromachined surfaces that are exposed to humid conditions. Our quantitative values for interfacial adhesion energies are determined from an in-situ optical measurement of deformations in partly-adhered cantilever beams. We coated micromachined cantilevers with either ODTS (C{sub 18}H{sub 37}SiCl{sub 3}) or FDTS (C{sub 8}F{sub 17}C{sub 2}H{sub 4}SiCl{sub 3}) with the objective of creating hydrophobic surfaces whose adhesion would be independent of humidity. In both cases, the adhesion energy is significantly lower than for uncoated, hydrophilic surfaces. For relative humidities (RH) less than 95% (ODTS) and 80% (FDTS) the adhesion energy was extremely low and constant. In fact, ODTS-coated beams exposed to saturated humidity conditions and long (48 hour) exposures showed only a factor of two increase in adhesion energy. Surprisingly, FDTS coated beams, which initially have a higher contact angle (115{degree}) with water than do ODTS coated beams (112{degree}), proved to be much more sensitive to humidity. The FDTS coated surfaces showed a factor of one hundred increase in adhesion energy after a seven hour exposure to 90% RH. Atomic force microscopy revealed agglomerated coating material after exposed to high RH, suggesting a redistribution of the monolayer film. This agglomeration was more prominent for FDTS than ODTS. These findings suggest a new mechanism for uptake of moisture under high humidity conditions. At high humidities, the silane coatings can reconfigure from a surface to a bulk phase leaving behind locally hydrophilic sites which increase the average measured adhesion energy. In order for the adhesion increase to be observed, a significant fraction of the monolayer must be converted from the surface to the bulk phase.
The connection is made between the normal-coordinate structural decomposition (NSD) and the vibronic molecular states and spectra of porphyrins. NSD is a procedure that provides a description of the distortion of a porphyrin from a D{sub 4h} symmetric reference structure in terms of equivalent displacements along the normal coordinates. Expressions for the optical absorption spectra with vibrational structure are developed with these NSD-determined deformations as parameters, and the expressions are applied to the UV-visible absorption spectra porphyrins.
We show that for general input sets linear feedback shift registers (LFSRS) do not provide compression comparable to current, standard algorithms, at least not on the current, standard input files. Rather, LFSRS provide performance on a par with simple, run-length encoding schemes. We exercised three different ways of using LFSRS on the Canterbury, Canterbury Oarge set, the Calgory Corpora, and on three, large graphics files of our own.
Wind-energy researchers at Sandia National Laboratories have developed a new, light-weight, modular data acquisition system capable of acquiring long-term, continuous, multi-channel time-series data from operating wind-turbines. New hardware features have been added to this system to make it more flexible and permit programming via telemetry. User-friendly Windows-based software has been developed for programming the hardware and acquiring, storing, analyzing, and archiving the data. This paper briefly reviews the major components of the system, summarizes the recent hardware enhancements and operating experiences, and discusses the features and capabilities of the software programs that have been developed.
Typical laboratory testing of Polycrystalline Diamond Compact (PDC) bits is performed on relatively rigid setups. Even in hard rock, PDC bits exhibit reasonable life using such testing schemes. Unfortunately, field experience indicates otherwise. In this paper, the authors show that introducing compliance in testing setups provides better simulation of actual field conditions. Using such a scheme, they show that chatter can be severe even in softer rock, such as sandstone, and very destructive to the cutters in hard rock, such as sierra white granite.
Al{sub 2}Cu thin films ({approximately}382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {approximately}3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron Microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30--70 {mu}m wide and 10--25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67{+-}2% Al and 33{+-}2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approximately}5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.
On rare occasions, the coining of a new term brings new ideas to a field by virtue of a shift in viewpoint. A recent example is complexity, which collected together, from a core of deep results in mathematics and hydrodynamics, a clan of fields whose kinship had been revealed by the new term itself. More often such appellations merely follow fashionable trends. So it took courage on the part of the founders of SUPERMAT to promote their vision. Marcel Ausloos (Universite de Liege, Belgium) and Gilbert Vacquier (Universite de Marseille, France) have shown us a way to resonate as a new chord in materials science. As the first conference on supermaterials, SUPERMAT and its companion SMART 99 have begun to reveal new branches of research from the established pathways explored in superconductivity. At the conclusion of SUPERMAT in Giens, France, the participants were as energized by the exciting science that had been covered during the week as they were impressed by the French food, wine, scenery and hospitality. If the definition of a supermaterial is not obvious now-after the conference-it was certainly not obvious before it. Nevertheless, the conferees were drawn inexorably together by the conference theme. Perhaps it is not appropriate to try to understand this self organization, which surely is even more complex than the self organization of electrons in a high temperature superconductor, the theory for which still eludes us after 13 years! A clue to the working definition of a supermaterial can be derived empirically from the topics that were discussed at SUPERMAT and SMART 99. In addition to superconductors, they heard about magnetic effects of many kinds, including giant and even colossal ones that presumably trump super ones, organic conductors, photoconductors, and even four-hundred-year-old Japanese ceramics. Topics discussed were synthesis, processing, characterization and theory, and applications.
Typical Laboratory testing of Polycrystalline Diamond Compact (PDC) bits is performed on relatively rigid setups. Even in hard rock, PDC bits exhibit reasonable life using such testing schemes. Unfortunately, field experience indicates otherwise. In this paper, they show that introducing compliance in testing setups, provides better simulation of actual field conditions. Using such a scheme, they show that chatter can be severe even in softer rock, such as sandstone, and very destructive to the cutters in hard rock, such as sierra white granite.
Peak x-ray powers as high as 280 {+-} 40 TW have been generated from the implosion of tungsten wire arrays on the Z Accelerator at Sandia National Laboratories. The high x-ray powers radiated by these z-pinches provide an attractive new driver option for high yield inertial confinement fusion (ICF). The high x-ray powers appear to be a result of using a large number of wires in the array which decreases the perturbation seed to the magnetic Rayleigh-Taylor (MRT) instability and diminishes other 3-D effects. Simulations to confirm this hypothesis require a 3-D MHD code capability, and associated databases, to follow the evolution of the wires from cold solid through melt, vaporization, ionization, and finally to dense imploded plasma. Strong coupling plays a role in this process, the importance of which depends on the wire material and the current time history of the pulsed power driver. Strong coupling regimes are involved in the plasmas in the convolute and transmission line of the powerflow system. Strong coupling can also play a role in the physics of the z-pinch-driven high yield ICF target. Finally, strong coupling can occur in certain z-pinch-driven application experiments.
This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating microstructure in metals and alloys. Specifically, {approx}25{micro}m diameter micro-end mills are made from cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks by ion beam sputtering. A 20 keV focused gallium beam defines tool cutting edges having radii of curvature < 0.1{micro}m. Micro-end mills having 2, 4 and 5 cutting edges successfully machine small trenches in 6061-T4 aluminum, brass, 4340 steel and polymethyl methacrylate. Machined trench widths are approximately equal to the tool diameters and surface roughnesses (rms) are {approx}150 nm or less. Microtools are robust and operate for more than 6 hours without fracture. Results from ultra-precision machining aluminum at feed rates as high as 50 mm/minute are included.
This paper presents techniques for fabricating microscopic, nonplanar features in a variety of materials. Micro-grooving and micro-threading tools having cutting dimensions of 10-30{micro}m are made by focused ion beam sputtering and used in ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide. This creates cutting edges having radii of curvature less than 0.4 {micro}m, and rake features similar to conventional lathe tools. Clearance for minimizing frictional drag of a tool results from the sputter yield dependence on ion herd target incidence angle. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close matching between tool width and feature size. Microtools controllably machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061-T6 Al cylindrical substrates. Micro-grooving tools also fabricate sinusoidal waveform features in polished metal substrates.
Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (>20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment.