Publications

The role of force measurements in vibration testing is discussed. The rational for a vibration test based on the extremal control of force and acceleration is developed. The differences between force measurements in vibration testing and modal testing is discussed. Several methods for estimating the input force in a vibration test are outlined.

A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator is a self-contained IBM-PC compatible based system that executes at a speed faster than real-time. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulation of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and causality conditions.

This is the final report of a program to develop a commercial, high-efficiency, low-cost concentrator solar cell compatible with Spectrolab`s existing manufacturing infrastructure for space solar cells. The period covered is between 1991 and 1993. The program was funded through Sandia National Laboratories through the DOE concentrator initiative and, was also cost shared by Spectrolab. As a result of this program, Spectrolab implemented solar cells achieving an efficiency of over 19% at 200 to 300X concentration. The cells are compatible with DOE guidelines for a cell price necessary to achieve a cost of electricity of 12 cents a kilowatthour.

The theoretical and numerical background for the finite element computer program, COYOTE II, is presented in detail. COYOTE II is designed for the multi-dimensional analysis of nonlinear heat conduction problems and other types of diffusion problems. A general description of the boundary value problems treated by the program is presented. The finite element formulation and the associated numerical methods used in COYOTE II are also outlined. Instructions for use of the code are documented in SAND94-1179; examples of problems analyzed with the code are provided in SAND94-1180.

Four commercial exterior fiber optic intrusion detection sensors installed in a gravel test bed have been evaluated. These are the FOIDS models 1000 and 500, Sabreline, and Fiber SenSys model M106E. In addition, FOIDS models 1000 and 500 installed on a fence were evaluated. The data was obtained from a perimeter sensor test field in Albuquerque.

User instructions are given for the finite element computer program, COYOTE II. COYOTE II is designed for the multi-dimensional analysis of nonlinear heat conduction problems including the effects of enclosure radiation and chemical reaction. The theoretical background and numerical methods used in the program are documented in SAND94-1173. Examples of the use of the code are presented in SAND94-1180.

This study identifies technologies required to extend the capabilities of airborne light detection and ranging (lidar) systems and establish the feasibility of autonomous space-based lidars. Work focused on technologies that enable the development of a lightweight, low power, rugged and autonomous Differential Absorption Lidar (DIAL) instruments. Applications for airborne or space-based DIAL include the measurement of water vapor profiles in support of climate research and processing-plant emissions signatures for environmental and nonproliferation monitoring. A computer-based lidar performance model was developed to allow trade studies to be performed on various technologies and system configurations. It combines input from the physics (absorption line strengths and locations) of the problem, the system requirements (weight, power, volume, accuracy), and the critical technologies available (detectors, lasers, filters) to produce the best conceptual design. Conceptual designs for an airborne and space-based water vapor DIAL, and a detailed design of a ground-based water vapor DIAL demonstration system were completed. Future work planned includes the final testing, integration, and operation of the demonstration system to prove the capability of the critical enabling technologies identified.

The shock-loading of natural materials by an impact or explosion can result in the formation of modified and altered phases. In order to characterize the resulting material and to evaluate the extent of shock modification, the authors have used nuclear magnetic resonance (NMR) spectroscopy to examine several experimentally shocked minerals. In three related NMR studies, they have (1) examined shocked clinoptilolite, (2) performed a preliminary analysis of shocked quartz, and (3) reproduced shocked quartz results with detailed spectral deconvolutions, and extended it with NMR analysis of shocked feldspar powders.

During July-September, 1993, Sandia National Laboratories, in cooperation with Far West Capital, drilled a 4000 feet exploratory slimhole (3.9 inch diameter) in the Steamboat Hills geothermal field near Reno, Nevada. This well was part of Sandia`s program to evaluate slimholes as a geothermal exploration tool. During and after drilling the authors performed four series of production and injection tests while taking downhole (pressure-temperature-spinner) and surface (wellhead pressure and temperature, flow rate) data. In addition to these measurements, the well`s data set includes: continuous core (with detailed log); borehole televiewer images of the wellbore`s upper 500 feet; daily drilling reports from Sandia and from drilling contractor personnel; daily drilling fluid record; numerous temperature logs; and comparative data from production and injection wells in the same field. This report contains: (1) a narrative account of the drilling and testing, (2) a description of equipment used, (3) a brief geologic description of the formation drilled, (4) a summary and preliminary interpretation of the data, and (5) recommendations for future work.

This report documents the characterization of thin copper films grown at Sandia as part of on-going research in copper CVD involving Sandia and Schumacher, Inc. The films have been grown using the copper (1) CVD precursor (hfac)Cu(TMVS), which was first developed by Schumacher and has been supplied to Sandia by that company. The CVD was performed using a novel technique in which direct liquid coinjection of (hfac)Cu(TMVS) and TMVS (trimethylvinylsilane) into a commercial reactor is utilized. Films were deposited onto silicon nitride substrates at temperatures in the range of 220-250{degrees}C, with growth rates in the range of 400-800 {angstrom}/min. These films have been analyzed by a variety of techniques, with an emphasis on factors that may influence the resistivity, including thickness, purity, density, grain size, and stress. The authors show that these films have as-deposited resistivities of 1.86 {+-} 0.1 {mu}{Omega}-cm, or 1.82 {+-} 0.1 {mu}{Omega}-cm after accounting for surface scattering effects. The latter value is only 0.14 {mu}{Omega}-cm above the value for high purity bulk copper. The authors discuss factors that may account for this residual resistivity. They also discuss the effects of film surface roughness on film thickness and resistivity measurements, noting some potential problems associated with the commonly used surface profilometry technique. These results help to establish (hfac)Cu(TMVS) as one of the most promising available copper CVD precursors for metallization applications.

A Zinc/Air Battery Review and Strategic Planning Meeting was held in 1993. One outcome of the meeting was recognition of the need for a report on the current status of the technology. This report contains contributions from many of the attendees at the above meeting and expresses their views on where the technology is today and what could/should be done to improve its performance.

As the product requirements are defined, business processes and procedures should be redeveloped in order to fully realize the benefits of the product. Process Quality Management Improvement (PQMI) can be used as a methodology to redevelop business processes and procedures for an organization. Business processes and procedures are an integral part of the Product Realization Process (PRP). This document focuses on the development of business processes and procedures. The business processes and procedures should be developed concurrently with the product. This enables the product and project as a whole to be transitioned smoothly and successfully. Without business processes and procedures to back up the changes brought with the new product, the product will not be used to its full potential and the transition will not be as smooth. Developing business processes and procedures lends itself to the PQMI methodology because PQMI calls for all the information needed to develop business processes and procedures and ensures the business processes and procedures are developed in a quality manner. The PQMI steps are: (1) Establishing process management responsibilities; (2) Defining Processes and Identifying Customer Requirements; (3) Defining and Establishing Measures; (4) Assessing Conformance to Customer Requirements; (5) Investigating Processes to Identify Improvement Opportunities; (6) Ranking Improvement Opportunities and Setting Objectives; and (7) Improving Process Quality. The successful implementation of a product can be attributed to the standardization of business processes and procedures. These business processes and procedures describe in detail the day to day operations of a project. The development of business processes and procedures provide and environment for agile product realization.

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A specially designed ultrahigh vacuum in situ surface analysis and wetting system has been constructed to study the spreading of liquid metal solders on carefully prepared and well-characterized solid substrates. Initial studies have been completed for the spreading of pure tin solder on copper substrates in the absence of any fluxing agent. Surface chemical analysis by x-ray photoelectron spectroscopy showed the air-exposed surface to consisted of about 3 nm of Cu{sub 2}O, while the as-received surface consisted of about 8 nm of Cu{sub 2}O. The sputter-cleaned surface contained less than one monolayer (0.3 nm) of Cu{sub 2}O. Sample surfaces were prepared and spreading experiments performed without intermediate exposure of the surfaces to contaminating atmospheres. Solder spreading was performed under 50 torr of highly purified helium gas to allow for adequate thermal coupling between the solder and the substrate. Spreading experiments utilizing a linear temperature ramp show that pure tin solder spreads readily on oxidized copper surfaces at elevated temperatures. The initiation temperature for rapid tin spreading on the as-received copper surface was 325{degrees}C, similar to the temperature where isothermal spreading changes activation energy or rate. Decreasing the thickness of the oxide on the surface lowered the observed temperature for the initiation of spreading and increased the rate of spreading. On the sputter-cleaned copper surface, rapid solder spreading was observed immediately upon melting of the solder.

Sandia recently completed an updated strategic plan, the essence of which is presented in chapter 4. Sandia`s Strategic Plan 1994 takes its direction from DOE`s Fueling a Competitive Economy: Strategic Plan and provides tangible guidance for Sandia`s programs and operations. Although it is impossible to foresee precisely what activities Sandia will pursue many years from now, the strategic plan makes one point clear: the application of our scientific and engineering skills to the stewardship of the nation`s nuclear deterrent will be central to our service to the nation. We will provide the necessary institutional memory and continuity, experience base, and technical expertise to ensure the continued safety, security, and reliability of the nuclear weapons stockpile. As a multiprogram laboratory, Sandia will also continue to focus maximum effort on a broad spectrum of other topics consistent with DOE`s enduring core mission responsibilities: Defense (related to nuclear weapons), Energy, Environment (related to waste management and environmental remediation), and Basic Science.

The Department of Energy Order 5500.3A requires facility-specific hazards assessments be prepared, maintained, and used for emergency planning purposes. This hazards assessment document describes the chemical and radiological hazards associated with the Sandia Lightning Simulation Facility, Building 888. The entire inventory was screened according to the potential airborne impact to onsite and offsite individuals. The air dispersion model, ALOHA, estimated pollutant concentrations downwind from the source of a release, taking into consideration the toxicological and physical characteristics of the release site, the atmospheric conditions, and the circumstances of the release. The greatest distance at which a postulated facility event will produce consequences exceeding the Early Severe Health Effects threshold is 23 meters. The highest emergency classification is a Site Area Emergency. The Emergency Planning Zone is 65 meters.

The Yucca Mountain Project, managed by the U.S. Department of Energy, is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain on and adjacent to the Nevada Test Site. As part of the site characterization, a series of in situ thermomechanical experiments are planned, which are to be conducted in the Exploratory Studies Facility (ESF). In this report, the results of preliminary analyses of three of the in situ thermomechanical experiments are presented. The major objective of these analyses was to determine the boundaries of the thermally perturbed zones surrounding each of the experiments. The boundaries of the thermal zones needs to be known in order to avoid test interference between the experiments planned for the ESF. A second objective of these analyses was to calculate the displacements and stresses associated with the experiments, in order to advance the planning of the experiments.

A gridless technique called smooth particle hydrodynamics (SPH) has been coupled with the transient dynamics finite element code pronto. In this paper, a new weighted residual derivation for the SPH method will be presented, and the methods used to embed SPH within pronto will be outlined. Example SPH pronto calculations will also be presented. One major difficulty associated with the Lagrangian finite element method is modeling materials with no shear strength; for example, gases, fluids and explosive biproducts. Typically, these materials can be modeled for only a short time with a Lagrangian finite element code. Large distortions cause tangling of the mesh, which will eventually lead to numerical difficulties, such as negative element area or "bow tie" elements. Remeshing will allow the problem to continue for a short while, but the large distortions can prevent a complete analysis. SPH is a gridless Lagrangian technique. Requiring no mesh, SPH has the potential to model material fracture, large shear flows and penetration. SPH computes the strain rate and the stress divergence based on the nearest neighbors of a particle, which are determined using an efficient particle-sorting technique. Embedding the SPH method within pronto allows part of the problem to be modeled with quadrilateral finite elements, while other parts are modeled with the gridless SPH method. SPH elements are coupled to the quadrilateral elements through a contact-like algorithm. © 1994.

EXODUS II is a model developed to store and retrieve data for finite element analyses. It is used for preprocessing (problem definition), postprocessing (results visualization), as well as code to code data transfer. An EXODUS II data file is a random access, machine independent, binary file that is written and read via C, C++, or Fortran library routines which comprise the Application Programming Interface (API).

The CuPt-type ordering and dopant effects of In{sub 0.5}Ga{sub 0.5}P/GaAs epitaxial layers have been studied using spectroscopic ellipsometry and transmission electron microscopy. The degree of ordering was estimated by both transmission electron diffraction and direct band edge, E{sub 0}. Conventional lineshape fitting of E{sub 1}, E{sub 1}+{Delta}{sub 1}, and E{sub 2} gaps using the second derivative of pseudo dielectric functions shows that the peak position and oscillator strength of the E{sub 1} gap are basically a function of CuPt-type ordering whereas their broadening and phase depend mainly on carrier concentration. The decrease of E{sub 1} gap is explained in terms of CuPt-type ordering. In contrast to the E{sub 1} gap, all the lineshape parameters of the E{sub 2} gap depend mainly on CuPt-type ordering. This difference is discussed in terms of apparent {open_quotes}CuAu-type ordering{close_quotes} or Y2 structure which was observed by transmission electron diffraction.

A new die-level packaging technology, mBGA, is reported in this paper. The mBGA enables high circuit packaging density on multichip module (MCM), facilitates die testing to obtain ``known good die,`` and allows a cost effective module assembly. We have designed and fabricated a test vehicle to evaluate mBGA multichip module technology. This paper describes the mBGA technology and the test vehicle multichip module and reports preliminary results on the die test and burn-in, thermal performance and reliability studies.

The IC test industry has struggled for more than 30 years to establish a test approach that would guarantee a low defect level to the customer. We propose a comprehensive strategy for testing CMOS ICs that uses defect classes based on measured defect electrical properties. Defect classes differ from traditional fault models. Our defect class approach requires that the test strategy match the defect electrical properties, while fault models require that IC defects match the fault definition. We use data from Sandia Labs failure analysis and test facilities and from public literature. We describe test pattern requirements for each defect class and propose a test paradigm.

Several experimental melts were conducted using a moving mold electroslag remelting furnace. The conditions of electrode immersion depth, slag cap thickness, and melt current were varied. Mold wall temperatures and slag pool temperatures were measured and the heat flux through the mold wall was calculated. The relationships between varying ESR melt parameters and the resultant thermal conditions were examined. The thermal profile of the mold, the heat transfer to the mold coolant total and fractional, and the formation of a slag skin were studied.