Progress and future plans for MPC and A at Chelyabinsk-70 (open access)

Progress and future plans for MPC and A at Chelyabinsk-70

This paper describes that portion of the Nuclear Materials Protection, Control, and Accounting (MPC and A) program that is directed specifically to the needs of the All Russian Scientific Research Institute of Technical Physics (VNIITF), also called Chelyabinsk-70. Chelyabinsk-70 is located in the Ural Mountains, approximately 2000 km east of Moscow and 100 km south of Ekaterinburg. The MPC and A work that has been completed, is underway and planned at the facility will be described. During the first two years of the VNIITF project, emphasis was on the Pulse Research Reactor Facility (PRR), which contains one metal and two liquid pulse reactors and associated nuclear material storage rooms and a control center. A commissioning of the PRR was held in May of 1998. With the completion of the MPC and A work in the PRR, new physical protection work is focusing on other areas. VNIITF-wide physical protection initiatives underway include access control and computerized badging systems, and a central MPC and A control system. Measured physical inventory taking is a high priority for the VNIITF Project Team. A VNIITF-wide computerized accounting system is also being developed for the large and diverse inventory of nuclear material subject to MPC and …
Date: July 8, 1999
Creator: Apt, K.; Blasy, J.; Bukin, D.; Cahalane, P.; Churikov, Y.; Curtis, D. et al.
System: The UNT Digital Library
A novel condenser for EUV lithography ring-field projection optics (open access)

A novel condenser for EUV lithography ring-field projection optics

A condenser for a ring-field extreme ultra-violet (EUV) projection lithography camera is presented. The condenser consists of a gently undulating mirror, that we refer to as a ripple plate, and which is illuminated by a collimated beam at grazing incidence. The light is incident along the ripples rather than across them, so that the incident beam is reflected onto a cone and subsequently focused on to the arc of the ring field. A quasistationary illumination is achieved, since any one field point receives light from points on the ripples, which are distributed throughout the condenser pupil. The design concept can easily be applied to illuminate projection cameras with various ring-field and numerical aperture specifications. Ray-tracing results are presented of a condenser for a 0.25 NA EUV projection camera.
Date: July 15, 1999
Creator: Chapman, H. & Nugent, K. A.
System: The UNT Digital Library
Predicting the Future at Yucca Mountain (open access)

Predicting the Future at Yucca Mountain

This paper summarizes a climate-prediction model funded by the DOE for the Yucca Mountain nuclear waste repository. Several articles in the open literature attest to the effects of the Global Ocean Conveyor upon paleoclimate, specifically entrance and exit from the ice age. The data shows that these millennial-scale effects are duplicated on the microscale of years to decades. This work also identifies how man may have influenced the Conveyor, affecting global cooling and warming for 2,000 years.
Date: July 1, 1999
Creator: Wilson, J. R.
System: The UNT Digital Library
Clinical implementation of the Peregrine Monte Carlo dose calculations system for photon beam therapy (open access)

Clinical implementation of the Peregrine Monte Carlo dose calculations system for photon beam therapy

PEREGRINE is a 3D Monte Carlo dose calculation system designed to serve as a dose calculation engine for clinical radiation therapy treatment planning systems. Taking advantage of recent advances in low-cost computer hardware, modern multiprocessor architectures and optimized Monte Carlo transport algorithms, PEREGRINE performs mm-resolution Monte Carlo calculations in times that are reasonable for clinical use. PEREGRINE has been developed to simulate radiation therapy for several source types, including photons, electrons, neutrons and protons, for both teletherapy and brachytherapy. However the work described in this paper is limited to linear accelerator-based megavoltage photon therapy. Here we assess the accuracy, reliability, and added value of 3D Monte Carlo transport for photon therapy treatment planning. Comparisons with clinical measurements in homogeneous and heterogeneous phantoms demonstrate PEREGRINE's accuracy. Studies with variable tissue composition demonstrate the importance of material assignment on the overall dose distribution. Detailed analysis of Monte Carlo results provides new information for radiation research by expanding the set of observables.
Date: July 1, 1999
Creator: Albright, N; Bergstrom, P M; Daly, T P; Descalle, M; Garrett, D; House, R K et al.
System: The UNT Digital Library
Magnetic properties of Dy in Pb{sub 2}Sr{sub 2}DyCu{sub 3}O{sub 8}. (open access)

Magnetic properties of Dy in Pb{sub 2}Sr{sub 2}DyCu{sub 3}O{sub 8}.

Superconductivity can be induced at high temperatures in Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8} (R - rare earth) by partially doping Ca{sup 2+} for R{sup 3+}. In order to understand the interplay between magnetism and superconductivity, the magnetic properties of the parent compounds, Pb{sub 2}Sr{sub 2}RCu{sub 3}O{sub 8}, have been studied. The work presented here includes magnetic susceptibility and specific heat measurements on R = Dy and extends our previous studies on R = Ce, Pr, Tb, Ho and Er. Specific heat experiments suggest that the Dy ions order antiferromagnetically with an ordering temperature of 1.3K. The magnetic susceptibility data are in good agreement with the susceptibility calculated using crystal field parameters that are extrapolated from previous modeling of the R = Er and Ho analogs of this series.
Date: July 2, 1999
Creator: Movshovich, R.; Skanthakumar, S. & Soderholm, L.
System: The UNT Digital Library
Recent Development of Metallic Materials (open access)

Recent Development of Metallic Materials

Metallic materials play a vital role in the development of advanced engineering systems for industrial applications. In this paper, the recent development of two metallic alloy families will be briefly reviewed: (1) ordered intermetallics, and (2) bulk metallic glasses. Ordered intermetallic alloys based on aluminides and silicides possess many promising properties for structural use at elevated temperatures in hostile environments. This is because these alloys have excellent oxidation and corrosion resistance, high temperature strength, and relatively low material density. Bulk metallic glasses containing multiple alloying elements constitute a new and exciting class of metallic materials with attractive mechanical, chemical, and magnetic properties for structural and functional use. Recent development indicates that bulk metallic glasses with high glass forming ability can be readily produced by conventional melting and casting techniques.
Date: July 2, 1999
Creator: Liu, C.T. & Nieh, T.G.
System: The UNT Digital Library
Training options for countering nuclear smuggling (open access)

Training options for countering nuclear smuggling

The burden of stopping a nuclear smuggling attempt at the border rests most heavily on the front-line customs inspector. He needs to know how to use the technological tools at his disposal, how to discern tell-tale anomalies in export documents and manifests, how to notice psychological signs of a smuggler's tension, and how to search anything that might hide nuclear material. This means that assistance in the counter-nuclear smuggling training of customs officers is one of the most critical areas of help that the United States can provide. This paper discusses the various modes of specialized training, both in the field and in courses, as well as the types of assistance that can be provided. Training for nuclear customs specialists, and supervisors and managers of nuclear smuggling detection systems is also important, and differs from front-line inspector training in several aspects. The limitations of training and technological tools such as expert centers that will overcome these limitations are also discussed. Training assistance planned by DOE/NN-43 to Russia within the Second Line of Defense program is discussed in the light of these options, and future possibilities for such training are projected.
Date: July 1, 1999
Creator: Ball, D Y & Erickson, S A
System: The UNT Digital Library
The role of rare-earth dopants in nanophase zirconia catalysts for automotive emission control. (open access)

The role of rare-earth dopants in nanophase zirconia catalysts for automotive emission control.

Rare earth (RE) modification of automotive catalysts (e.g., ZrO{sub 2}) for exhaust gas treatment results in outstanding improvement of the structural stability, catalytic functions and resistance to sintering at high temperatures. Owing to the low redox potential of nonstoichiometric CeO{sub 2}, oxygen release and intake associated with the conversion between the 3+ and 4+ oxidation states of the Ce ions in Ce-doped ZrO{sub 2} provide the oxygen storage capacity that is essentially to effective catalytic functions under dynamic air-to-fuel ratio cycling. Doping tripositive RE ions such as La and Nd in ZrO{sub 2}, on the other hand, introduces oxygen vacancies that affect the electronic and ionic conductivity. These effects, in conjunction with the nanostructure and surface reactivity of the fine powders, present a challenging problem in the development of better ZrO{sub 2}-containing three-way catalysts. We have carried out in-situ small-to-wide angle neutron diffraction at high temperatures and under controlled atmospheres to study the structural phase transitions, sintering behavior, and Ce{sup 3+} {leftrightarrow} Ce{sup 4+} redox process. We found substantial effects due to RE doping on the nature of aggregation of nanoparticles, defect formation, crystal phase transformation, and metal-support interaction in ZrO{sub 2} catalysts for automotive emission control.
Date: July 16, 1999
Creator: Loong, C.-K. & Ozawa, M.
System: The UNT Digital Library
Optical cleanliness specifications and cleanliness verification (open access)

Optical cleanliness specifications and cleanliness verification

Optical cleanliness is important to NIF because it results in beam obscuration and scatter losses which occur in the front-end (containing over 20,000 small optics) and the large-aperture portions of the laser (containing 7,300 optics in 192 beamlines). The level of particulate cleanliness necessary for NIF, is similar to the scatter loss due to surface roughness. That is, the scatter loss should not exceed 2.5 x 10{sup {minus}5} per surface. Establishing requirements for optical and structural surface cleanliness needs consideration of both particulate and organic thin-film cleanliness. Both forms of cleanliness may be specified using guidelines specified in Military Standard 1246C and are referred to as cleanliness Levels. This Military Standard is described briefly and displayed in tables and charts. The presence of organic thin-films on structural surfaces is of particular concern if the contaminated surface is near solgel coated optics (solgel coatings provide an antireflection (AR) quality); or the optic is in a vacuum. In a vacuum, organic contaminant molecules have a much high probability of transporting from their source to a solgel-coated optic and thereby result in the rapid change in the transmission of the antireflection coating. Optical surface cleanliness can be rapidly degraded if a clean optic …
Date: July 1, 1999
Creator: Stowers, I. F.
System: The UNT Digital Library
Thermal-hydraulic development a small, simplified, proliferation-resistant reactor. (open access)

Thermal-hydraulic development a small, simplified, proliferation-resistant reactor.

This paper addresses thermal-hydraulics related criteria and preliminary concepts for a small (300 MWt), proliferation-resistant, liquid-metal-cooled reactor system. A main objective is to assess what extent of simplification is achievable in the concepts with the primary purpose of regaining economic competitiveness. The approach investigated features lead-bismuth eutectic (LBE) and a low power density core for ultra-long core lifetime (goal 15 years) with cartridge core replacement at end of life. This potentially introduces extensive simplifications resulting in capital cost and operating cost savings including: (1) compact, modular, pool-type configuration for factory fabrication, (2) 100+% natural circulation heat transport with the possibility of eliminating the main coolant pumps, (3) steam generator modules immersed directly in the primary coolant pool for elimination of the intermediate heat transport system, and (4) elimination of on-site fuel handling and storage provisions including rotating plug. Stage 1 natural circulation model and results are presented. Results suggest that 100+% natural circulation heat transport is readily achievable using LBE coolant and the long-life cartridge core approach; moreover, it is achievable in a compact pool configuration considerably smaller than PRISM A (for overland transportability) and with peak cladding temperature within the existing database range for ferritic steel with oxide layer …
Date: July 2, 1999
Creator: Farmer, M. T.; Hill, D. J.; Sienicki, J. J.; Spencer, B. W. & Wade, D. C.
System: The UNT Digital Library
HIGH RESOLUTION MICROTOMOGRAPHY FOR DENSITY AND SPATIAL INFORMATION ABOUT WOOD STRUCTURES. (open access)

HIGH RESOLUTION MICROTOMOGRAPHY FOR DENSITY AND SPATIAL INFORMATION ABOUT WOOD STRUCTURES.

Microtomography has successfully been used to characterize loss of structural integrity of wood. Tomographic images were generated with the newly developed third generation x-ray computed microtomography (XCMT) instrument at the X27A beamline at the National Synchrotron Light Source (NSLS). The beamline is equipped with high-flux x-ray monochromator based on multilayer optics developed for this application. The sample is mounted on a translation stage with which to center the sample rotation, a rotation stage to perform the rotation during data collection and a motorized goniometer head for small alignment motions. The absorption image is recorded by a single-crystal scintillator, an optical microscope and a cooled CCD array detector. Data reconstruction has provided three-dimensional geometry of the heterogeneous wood matrix in microtomographic images. Wood is a heterogeneous material composed of long lignocellulose vessels. Although wood is a strong natural product, fungi have evolved chemical systems that weaken the strength properties of wood by degrading structural vessels. Tomographic images with a resolution of three microns were obtained nonintrusively to characterize the compromised structural integrity of wood. Computational tools developed by Lindquist et al (1996) applied to characterize the microstructure of the tomographic volumes.
Date: July 22, 1999
Creator: ILLMAN,B.
System: The UNT Digital Library
Calibration of seismic wave propagation in Jordan (open access)

Calibration of seismic wave propagation in Jordan

The Natural Resources Authority of Jordan (NRA), the USGS and LLNL have a collaborative project to improve the calibration of seismic propagation in Jordan and surrounding regions. This project serves common goals of CTBT calibration and earthquake hazard assessment in the region. These objectives include accurate location of local and regional earthquakes, calibration of magnitude scales, and the development of local and regional propagation models. In the CTBT context, better propagation models and more accurately located events in the Dead Sea rift region can serve as (potentially GT5) calibration events for generating IMS location corrections. The detection and collection of mining explosions underpins discrimination research. The principal activity of this project is the deployment of two broadband stations at Hittiyah (south Jordan) and Ruweishid (east Jordan). These stations provide additional paths in the region to constrain structure with surface wave and body wave tomography. The Ruweishid station is favorably placed to provide constraints on Arabian platform structure. Waveform modeling with long-period observations of larger earthquakes will provide constraints on 1-D velocity models of the crust and upper mantle. Data from these stations combined with phase observations from the 26 short-period stations of the Jordan National Seismic Network (JNSN) may allow …
Date: July 23, 1999
Creator: Al-Husien, A.; Amrat, A.; Harris, D.; Mayeda, K.; Nakanishi, K.; Rodgers, A. et al.
System: The UNT Digital Library
Commercial viability of hybrid vehicles : best household use and cross national considerations. (open access)

Commercial viability of hybrid vehicles : best household use and cross national considerations.

Japanese automakers have introduced hybrid passenger cars in Japan and will soon do so in the US. In this paper, we report how we used early computer simulation model results to compare the commercial viability of a hypothetical near-term (next decade) hybrid mid-size passenger car configuration under varying fuel price and driving patterns. The fuel prices and driving patterns evaluated are designed to span likely values for major OECD nations. Two types of models are used. One allows the ''design'' of a hybrid to a specified set of performance requirements and the prediction of fuel economy under a number of possible driving patterns (called driving cycles). Another provides an estimate of the incremental cost of the hybrid in comparison to a comparably performing conventional vehicle. In this paper, the models are applied to predict the NPV cost of conventional gasoline-fueled vehicles vs. parallel hybrid vehicles. The parallel hybrids are assumed to (1) be produced at high volume, (2) use nickel metal hydride battery packs, and (3) have high-strength steel bodies. The conventional vehicle also is assumed to have a high-strength steel body. The simulated vehicles are held constant in many respects, including 0-60 time, engine type, aerodynamic drag coefficient, tire …
Date: July 16, 1999
Creator: Santini, D. J. & Vyas, A. D.
System: The UNT Digital Library
Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}. (open access)

Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}.

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Date: July 30, 1999
Creator: Bordallo, H. N.; Christianson, A.; Drulis, H.; Havela, L.; Iwasieczko, W.; Kolomiets, A. V. et al.
System: The UNT Digital Library
Complete regional waveform modeling to estimate seismic velocity structure and source parameters for CTBT monitoring (open access)

Complete regional waveform modeling to estimate seismic velocity structure and source parameters for CTBT monitoring

The velocity structures and source parameters estimated by waveform modeling provide valuable information for CTBT monitoring. The inferred crustal and uppermost mantle structures advance understanding of tectonics and guides regionalization for event location and identification efforts. Estimation of source parameters such as seismic moment, depth and mechanism (whether earthquake, explosion or collapse) is crucial to event identification. In this paper we briefly outline some of the waveform modeling research for CTBT monitoring performed in the last year. In the future we will estimate structure for new regions by modeling waveforms of large well-observed events along additional paths. Of particular interest will be the estimation of velocity structure in aseismic regions such as most of Africa and the Former Soviet Union. Our previous work on aseismic regions in the Middle East, north Africa and south Asia give us confidence to proceed with our current methods. Using the inferred velocity models we plan to estimate source parameters for smaller events. It is especially important to obtain seismic moments of earthquakes for use in applying the Magnitude-Distance Amplitude Correction (MDAC; Taylor et al., 1999) to regional body-wave amplitudes for discrimination and calibrating the coda-based magnitude scales.
Date: July 23, 1999
Creator: Bredbeck, T.; Rodgers, A. & Walter, W.
System: The UNT Digital Library
Progress toward hydrogen peroxide micropulsion (open access)

Progress toward hydrogen peroxide micropulsion

A new self-pressurizing propulsion system has liquid thrusters and gas jet attitude control without heavy gas storage vessels. A pump boosts the pressure of a small fraction of the hydrogen peroxide, so that reacted propellant can controllably pressurize its own source tank. The warm decomposition gas also powers the pump and is supplied to the attitude control jets. The system has been incorporated into a prototype microsatellite for terrestrial maneuvering tests. Additional progress includes preliminary testing of a bipropellant thruster, and storage of unstabilized hydrogen peroxide in small sealed tanks.
Date: July 8, 1999
Creator: Whitehead, J. C.; Dittman, M. D. & Ledebuhr, A. G.
System: The UNT Digital Library
Photorefractivity in liquid crystals doped with a soluble conjugated polymer. (open access)

Photorefractivity in liquid crystals doped with a soluble conjugated polymer.

Photoconductive polymers are doped into liquid crystals to create a new mechanism for space-charge field formation in photorefractive liquid crystal composites. The composites contain poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV) and the electron acceptor N,N{prime}-dioctyl-1,4:5,8-naphthalenediimide, NI. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 {micro}m. We show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile species due to hole migration along the BEH-PPV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.
Date: July 7, 1999
Creator: Niemczyk, M. P.; Svec, W. A.; Wasielewski, M. R. & Wiederrecht, G. P.
System: The UNT Digital Library
A Database for Reviewing and Selecting Radioactive Waste Treatment Technologies and Vendors (open access)

A Database for Reviewing and Selecting Radioactive Waste Treatment Technologies and Vendors

Several attempts have been made in past years to collate and present waste management technologies and solutions to waste generators. These efforts have been manifested as reports, buyers' guides, and databases. While this information is helpful at the time it is assembled, the principal weakness is maintaining the timeliness and accuracy of the information over time. In many cases, updates have to be published or developed as soon as the product is disseminated. The recently developed National Low-Level Waste Management Program's Technologies Database is a vendor-updated Internet based database designed to overcome this problem. The National Low-Level Waste Management Program's Technologies Database contains information about waste types, treatment technologies, and vendor information. Information is presented about waste types, typical treatments, and the vendors who provide those treatment methods. The vendors who provide services update their own contact information, their treatment processes, and the types of wastes for which their treatment process is applicable. This information is queriable by a generator of low-level or mixed low-level radioactive waste who is seeking information on waste treatment methods and the vendors who provide them. Timeliness of the information in the database is assured using time clocks and automated messaging to remind featured vendors …
Date: July 1, 1999
Creator: Marushia, P. C. & Schwinkendorf, W. E.
System: The UNT Digital Library
Lessons learned from U.S. Department of Defense 911-Bio Advanced Concept Technology Demonstrations. (open access)

Lessons learned from U.S. Department of Defense 911-Bio Advanced Concept Technology Demonstrations.

The US Department of Defense (DoD), in cooperation with other federal agencies, has taken many initiatives to improve its ability to support civilian response to a domestic biological terrorism incident. This paper discusses one initiative, the 911-Bio Advanced Concept Technology Demonstrations (ACTDs), conducted by the Office of the Secretary of Defense during 1997 to better understand: (1) the capability of newly developed chemical and biological collection and identification technologies in a field environment; (2) the ability of specialized DoD response teams to use these new technologies within the structure of cooperating DoD and civilian consequence management organizations; and (3) the adequacy of current modeling tools for predicting the dispersal of biological hazards. This paper discusses the experience of the ACTDs from the civilian community support perspective. The 911-Bio ACTD project provided a valuable opportunity for DoD and civilian officials to learn how they should use their combined capabilities to manage the aftermath of a domestic biological terrorism incident.
Date: July 6, 1999
Creator: Baldwin, T.; Gasper, W.; Lacher, L.; Newsom, D. & Yantosik, G.
System: The UNT Digital Library
High-resolution wavefront control using liquid crystal spatial light modulators (open access)

High-resolution wavefront control using liquid crystal spatial light modulators

Liquid crystal spatial light modulator technology appropriate for high-resolution wavefront control has recently become commercially available. Some of these devices have several hundred thousand controllable degrees of freedom, more than two orders of magnitude greater than the largest conventional deformable mirror. We will present results of experiments to characterize the optical properties of these devices and to utilize them to correct aberrations in an optical system. We will also present application scenarios for these devices in high-power laser systems.
Date: July 20, 1999
Creator: Bauman, B. J.; Brase, J. M.; Brown, C. G.; Cooke, J. B.; Kartz, M. W.; Olivier, S. S. et al.
System: The UNT Digital Library
Theory of the equation of state of hot dense matter (open access)

Theory of the equation of state of hot dense matter

Ab initio molecular dynamics calculations are adapted to treat dense plasmas for temperatures exceeding the electronic Fermi temperature. Extended electronic states are obtained in a plane wave basis by using pseudopotentials for the ion cores in the local density approximation to density functional theory. The method reduces to conventional first principles molecular dynamics at low temperatures with the expected high level of accuracy. The occurrence of thermally excited ion cores at high temperatures is treated by means of final state pseudopotentials. The method is applied to the shock compression Hugoniot equation of state for aluminum. Good agreement with experiment is found for temperatures ranging from zero through 105K.
Date: July 23, 1999
Creator: Barbee, T W; Surh, M & Yang, L H
System: The UNT Digital Library
A future vision of nuclear material information systems (open access)

A future vision of nuclear material information systems

To address the current and future needs for nuclear materials management and safeguards information, Lawrence Livermore National Laboratory envisions an integrated nuclear information system that will support several functions. The vision is to link distributed information systems via a common communications infrastructure designed to address the information interdependencies between two major elements: Domestic, with information about specific nuclear materials and their properties, and International, with information pertaining to foreign nuclear materials, facility design and operations. The communication infrastructure will enable data consistency, validation and reconciliation, as well as provide a common access point and user interface for a broad range of nuclear materials information. Information may be transmitted to, from, and within the system by a variety of linkage mechanisms, including the Internet. Strict access control will be employed as well as data encryption and user authentication to provide the necessary information assurance. The system can provide a mechanism not only for data storage and retrieval, but will eventually provide the analytical tools necessary to support the U.S. government's nuclear materials management needs and non-proliferation policy goals.
Date: July 18, 1999
Creator: Suski, N. & Wimple, C.
System: The UNT Digital Library
Adaptive optics high resolution spectroscopy: present status and future direction (open access)

Adaptive optics high resolution spectroscopy: present status and future direction

High resolution spectroscopy experiments with visible adaptive optics (AO) telescopes at Starfire Optical Range and Mt. Wilson have demonstrated that spectral resolution can be routinely improved by a factor of - 10 over the seeing-limited case with no extra light losses at visible wavelengths. With large CCDs now available, a very wide wavelength range can be covered in a single exposure. In the near future, most large ground-based telescopes will be equipped with powerful A0 systems. Most of these systems are aimed primarily at diffraction-limited operation in the near IR. An exciting new opportunity will thus open up for high resolution IR spectroscopy. Immersion echelle gratings with much coarser grooves being developed by us at LLNL will play a critical role in achieving high spectral resolution with a compact and low cost IR cryogenically cooled spectrograph and simultaneous large wavelength coverage on relatively small IR detectors. We have constructed a new A0 optimized spectrograph at Steward Observatory to provide R = 200,000 in the optical, which is being commissioned at the Starfire Optical Range 3.5m telescope. We have completed the optical design of the LLNL IR Immersion Spectrograph (LISPEC) to take advantage of improved silicon etching technology. Key words: adaptive …
Date: July 27, 1999
Creator: Alcock, C.; Angel, R.; Ciarlo, D.; Fugate, R. O.; Ge, J.; Kuzmenko, P. et al.
System: The UNT Digital Library
Intermetallic insertion anodes for lithium batteries. (open access)

Intermetallic insertion anodes for lithium batteries.

Intermetallic alloys have been investigated for many years as anode materials for lithium batteries and, more recently, as alternative electrodes to carbon, because of several intrinsic advantages including high capacity and safety. Some of the most studied alloys utilize tin as the active component because of its high theoretical capacity (996 mAh/g) and its slightly higher operating voltage (<400 mV) compared to metallic lithium. To date, the use of binary lithium alloys as anodes has been limited to the select number of main group elements (e.g. Sn) that can be lithiated at an appropriate voltage with acceptable kinetics. A major disadvantage of binary Li{sub x}M alloy systems is that major phase changes occur during the electrochemical cycling of lithium. Severe volume expansion and contraction of the metal matrix, which limit the cycle life of the lithium cell, normally accompany these phase changes. The. most successful approach to overcoming this limitation has been the use of intermetallic alloys MM{prime} consisting of two (or more) metals, at least one of which is an ''active'' alloying element (M) and the other an ''inactive'' (M{prime}) element. During the reaction with lithium, such a system breaks up into regions of Li{sub x}M and inactive M{prime}. …
Date: July 19, 1999
Creator: Johnson, C. S.; Kahaian, A. J.; Kepler, K. D.; Scott, M.; Thackerary, M. M. & Vaughey, J.
System: The UNT Digital Library