Publications

The Borehole Directional Radar System is a high-power, high- resolution tool that is being developed to locate lithologic layers of fractures away from a wellbore. The prototype is a 50-kW peak- power pulsed directional radar system that determines fracture location by transmitting powerful radar pulses, 8 nanoseconds in length, in a known direction from a borehole. The frequency spectrum of the pulses ranges up to the VHF band, which is between 30 and 300 MHz. The transmitter and receiver rotate in place, permitting the tool to scan for fractures in all directions from the borehole. Because discontinuities in the rock interrupt and reflect radar signals, signals that return to the tool's receiving antenna indicate fractures. The distance of the fracture from the borehole is determined by the time delay of the return signal. The radio frequency signal is sampled and transmitted to the surface by wireline at audio frequencies, and then reconstructed at the surface using a personal computer. The key to the tool's potential is its ability to accurately measure distance and direction of a lithologic discontinuity underground. This paper presents field test results that show the capabilities of the tool for locating lithological discontinuities up to 10.5 m (34.5 ft) away from a wellbore. Unique features of the system are discussed. Potential applications of the system are described, such as locating gas and oil reservoirs below a salt dome and possibly detecting a blow-out well with or without casing. 10 refs., 8 figs.

An empirical scaling relationship between the mean electric field and the breakdown time has been found. Many divergent sets of data were used from breakdown experiments on power lines, laser-triggered switches, trigatrons, e-beam triggered gaps, sharp-point electrode to plane gaps, and uniform field gaps. This relationship builds on the Felsenthal and Proud data and extends their breakdown time delay (formative time) data by three orders of magnitude and into the region of interest for triggered gas switching. The data indicates that electrically triggered gaps, laser-triggered gaps, and untriggered gaps are governed by the same time-delay processes. Predictions can be made of trigger gap geometry, trigger delays, and trigger polarity effects. Breakdown delays of sub-centimeter-long to at least 8-meter-long gaps in air with either high or low field-enhanced electrodes are described by this equation. In addition, this relationship appears to be valid for a variety of gases and even accurately predicts the breakdown delay of mixtures of air and SF/sub 6/. 13 refs., 12 figs., 1 tab.

Recovery of impact loaded samples is extremely difficult owing to the highly destructive post-shock environment. A variety of techniques have been introduced to accomplish this task for both organic and inorganic samples. The design principles underlying these techniques and the practical limitations encountered in applications are described. 3 figs.

Over the past several decades, many researchers have contributed to present understanding of the flashover of electrically stressed insulators in vacuum, and a wealth of theories have been proposed to explain the many surprising attributes of this complex breakdown mechanism. Surface flashover appears to comprise at least two distinct phenomena which can be distinguished as being cathode-initiated or anode-initiated, with the former having received by far the most attention. Several models describing cathode-initiated flashover have been built on the pioneering work of Boersch and coworkers, published in 1963, and credit the breakdown mechanism to the action of an intense secondary-electron-emission avalanche on the insulator surface. Other researchers consider the electron avalanche to be only partially, if at all, responsible, and invoke various hot-carrier effects in the insulator bulk, the surface interfacial region, or in a layer of gas adsorbed on the insulator surface. Anode-initiated flashover, which contends with the cathode-initiated variety for the breakdown of insulators of conventional design, is thought to involve bulk breakdown in a way related to treeing failure. In spite of the considerable effort applied to understanding vacuum surface flashover, no single theory appears capable of explaining all the data, and new and often unexpected observations continue to be made. 42 refs., 6 figs.

The need for ever-increasing miniaturization of airborne instrumentation through the use of surface mounted components closely placed on printed circuit boards highlights problems with traditional board cleaning methods. The reliability of assemblies which have been cleaned with vapor degreasing and spray cleaning can be seriously compromised by residual contaminants leading to solder joint failure, board corrosion, and even electrical failure of the mounted parts. In addition, recent government actions to eliminate fully halogenated chlorofluorocarbons (CFC) and chlorinated hydrocarbons from the industrial environment require the development of new cleaning materials and techniques. This paper will discuss alternative cleaning materials and techniques and results that can be expected with them. Particular emphasis will be placed on problems related to surface-mounted parts. These new techniques may lead to improved circuit reliability and, at the same time, be less expensive and less environmentally hazardous than the traditional systems. 5 refs.

The Recirculating Linear Accelerator (RLA) uses ion-focusing to provide the radial confinement of the beam. At the ends of the ion- channel racetrack, a ramped vertical magnetic field will be required to keep the beam in the channel. A sector field, whose strength increases with distance from the channel axis, has been proposed to provide an energy bandwidth for the transport system. This manuscript reports on design studies for coil systems that produce the required fields. It also describes particle simulations in the combined IFR-B-field transport system to address the issues of energy bandwidth and emittance growth. 4 refs., 6 figs.

Are single event upsets an important vulnerability or lethality issue for strategic systems Neutron-induced single events have become a part of the vulnerability analysis for nuclear weapon environments, but there has been no serious consideration of proton-induced single events from neutron particle beam environments. Is this appropriate This paper examines this concept.

As a result of the popularity of using HyperCard to rapidly prototype equipment and computer interfaces on Macintosh personal computers, the need ensued to evaluate prototype usability by collecting subjects' interactive performance data in real-time. Sandia National Laboratories, in collaboration with Stone Design Software, has developed ProtoTymer, a HyperCard stack that can time and record users' interactive sessions with prototypes developed using HyperCard. While operating in the background, ProtoTymer records the times, locations, and targets (objects clicked) of a subject's inputs during an interactive session. At the conclusion of the session, the resultant data file can be reviewed, summarized, printed, or transferred to a spreadsheet for statistical or graphical analysis. This paper describes ProtoTymer's design approach, features, limitations, and considerations for future versions. 2 refs., 4 figs.

TORE SUPRA is a fairly large supra conducting Tokamak (R = 2.350 m and r = 0.800 m) and has an original goal to withstand a large power removal (25 MW) during a 30 second long pulse. The monitoring of the plasma density and of the particle balance will be partially controlled by the pump limiter system. Depending on the amount of convected plasma power on these limiter and of the upgrading of the total injected power, the limiters are designed to remove in excess of 8 MW at steady state. 3 refs., 4 figs.

We compare the hydrogen assisted cracking resistance of wrought PH 13-8 Mo stainless steel alloyed with 0.4 to 1.0 wt.% palladium to the conventional alloy when aged to yield strengths of 1170--1250 MPa. Pd is found both in solid solution in the martensitic phase and also in the form of randomly distributed, incoherent PdAl precipitates in the modified alloy. Interfacial segregation of Pd to grain boundaries and lath boundaries is not observed. Intergranular hydrogen cracking is suppressed with Pd in slow strain rate tests conducted during electrochemical hydrogen charging of precharged samples. Hydrogen permeation analyses indicate that hydrogen ingress is not inhibited by Pd but that bulk diffusion rates are lowered relative to the conventional alloy. These results are consistent with the creation of a strong hydrogen trap, most likely the uniformly distributed PdAl phase, which lowers the levels of interfacially segregated hydrogen. 15 refs.

From an interplay between theory based on the effective-medium scheme and experiments, an extremely simple picture has evolved which is capable of describing a vast number of experimental quantities related to interaction of hydrogen with metals, especially the trapping of hydrogen at defects. It is shown that the trap strengths are determined mainly by the interstitial electron density, and any open structures in the lattice leads to a trap, with the vacancies and voids being the strongest traps. It is also found theoretically and experimentally that up to six hydrogen atoms can be accommodated in a vacancy, and the change in trap strengths with occupancy has been determined. Recent results for the trapping of deuterium to defects in Pd are discussed. 29 refs., 5 figs.

Recent experimental works on the effect of dose rate on the total dose failure threshold of MOS devices have shown that the failure level is strategic environments may be less than the failure level measured in the laboratory by a factor of 3 to 10. This difference in dose rate response raises concerns about using laboratory sources to predict the radiation hardness in strategic environments. A solution to the problem of determining the total dose hardness of piece parts is to perform lot acceptance testing at relevant dose rates such that the time dependent effects can be directly observed. A low cost method of measuring the total dose hardness of piece parts in the laboratory at requisite dose rates is presented. 11 refs., 5 figs.

The propulsion working fluid for the containment closure used at the Nevada Test Site consists of a mixture of a driver gas and the hot detonation products from the shaped charge that cuts the wall of the storage vessel. Nitrogen had always been used as the driver gas. However, helium gas, because of its superior propulsion characteristics, has enabled us to design considerably heavier and stronger gates. Operational times can be equal to or less than operational times when nitrogen gas was used. Assume, maintaining the same functional time, that an appreciably stronger steel/aluminum composite gate is designed and developed. The gate consists of two 3/4-in.-thick, high-strength 4340 circular steel plates imbedded in the two sides of the 7075-T73 aluminum forging. Mechanical circular keys are used to ensure the effective transfer of horizontal shear loads from aluminum to steel. Three point bending experiments on small composite beams were conducted to determine the effectiveness of the mechanical keying system. Also explored was structural adhesive used as a bonding and shear transfer mechanism. 4 refs., 8 figs., 1 tab.

The Seismic Verification Program at Sandia focuses on designing and building seismic monitoring systems which could be deployed within the Soviet Union. To support this effort, Sandia also is involved in developing and testing seismic components, and in evaluating system performance and new monitoring techniques. Seismic studies conducted under the latter task concentrate on analyzing regional seismic signals, recorded within 2000 km of the source. In-country monitoring stations would be able to exploit these regional signals to improve on the capabilities of external stations at teleseismic ranges. The principal advantages which regional signals offer are greater amplitudes and broader frequency bands. However, such signals are more complex and less well understood than teleseismic records. Ongoing studies at Sandia will help define the performance which can be expected from an in-country network. Other studies are testing new monitoring concepts which may further improve in-country capabilities. This presentation gives a brief overview of some of these projects.

Two important areas of hydrogen combustion with uncertainties are identified: (1) high-temperature combustion and (2) flame acceleration and deflagration-to-detonation transition (DDT). The uncertainties associated with high-temperature combustion may affect phenomena in a least four different accident scenarios: the in-cavity oxidation of combustible gases produced by core-concrete interactions, the combustion of hydrogen following high pressure melt ejection, the possibility of local detonations, and combustion in the BWR Mark I and Mark II secondary containments. The uncertainty in the area of DDT has increased importance due to recent experimental results that show that the detonability limit is nominally at or near the flammability limit for some mixture conditions. How these uncertainties may affect various accident scenarios is discussed and recommendations are made to reduce these uncertainties. 35 refs., 8 figs., 2 tabs.

In this work high frequency SPICE models were developed to simulate the hysteresis and saturation effects of toroidal shaped ferrite core inductors and transformers. The models include the nonlinear, multi-valued B-H characteristic of the core material, leakage flux, stray capacitances, and core losses. The saturation effects were modeled using two diode clamping arrangements in conjunction with nonlinear dependent sources. Two possible controlling schemes were developed for the saturation switch. One of the arrangements used the current flowing through a series RC branch to control the switch, while the other used a NAND gate. The NAND gate implementation of the switch proved to be simpler and the parameters associated with it were easier to determine from the measurements and the B-H characteristics of the material. Lumped parameters were used to simulate the parasitic effects. Techniques for measuring these parasitic are described. The models were verified using manganese-zinc ferrite-type toroidal cores and they have general applicability to all circuit analysis codes equivalent function blocks such as multipliers, adders, and logic components. 7 refs., 22 figs.

Knowledge of coal molecular structure is important in the understanding of coal reactivity. Computer-aided Molecular Design (CAMD) has been used to create and study three-dimensional models of several postulated coal structures (Given, Wiser, Solomon, and Shinn). Using molecular dynamics calculations, the minimum-energy conformations for each structural model have been compared. The physical densities of the minimum-energy conformations have been calculated, and are in agreement with experimental evidence. The frequencies of cross-linking hydrogen bonds have been evaluated for these structures. Finally, we have also begun to use CAMD to study model polymeric compounds, whose structure and reactivity may give new insights into coal conversion processes. 15 refs., 5 figs., 2 tabs.

Transient burning of TiH/sub X//KClO/sub 4/ in a closed system is formulated including the effect of condensed species. Thermodynamic properties are evaluated using both BLAKE and TIGER computer codes. Three different equations of state for gaseous species are used and their effect on the burning rate is evaluated. For more accurate transient burning analysis, a pressure dependent covolume for gaseous species is generated. The effect of pressure dependent covolume as well as the condensed species on transient burning is evaluated. Both parameters are found to be important when the burning rate at high loading densities in a closed system is considered. At high loading densities, condensed species become important not only because of the their effect on thermodynamic properties but also due to the volume occupied by these species. 11 refs., 2 figs., 2 tabs.

The winding process is encountered frequently in manufacturing, such as winding of polymer films and paper, laminated pressure vessel construction, and the manufacture of wound capacitors. The winding of capacitors will typically involve hundreds of plies of conductor and dielectric wound over a core. Due to the large number of layers, the calculation of the mechanical studies within a wound capacitor is a significant computational task. The focus of Part II of this paper is the formulation and application of optimization techniques for the design of wound capacitors. The design criteria to be achieved is a specified uniform wound tension in a capacitor. The paper will formulate an optimization statement of the wound capacitor design problem, develop a technique for reducing the numerical calculation required to repeatedly analyze the capacitor as required by the optimization algorithm, and apply the technique to an example. 4 refs., 13 figs., 4 tabs.

Horizontal stress directions (azimuths) determined from anelastic strain recovery (ASR) and differential strain curve analyses (DSCA) were compared with those from wellbore breakouts detected by borehole televiewer and oriented caliper logs. The ASR/DSCA techniques appear to be more sensitive then the log techniques and provided stress azimuth predictions at depth intervals where the log data did not. Stress azimuth determinations were also made from other core analyses techniques, which, like ASR/DSCA, are associated with the formation of stress release microcracks. Preliminary insights were obtained in the applicability of these other techniques. This work provides information on the stresses at two well sites 3.6 miles apart in Western Colorado; and showing the comparative data in this context provides information on how to apply these techniques and provides an understanding of the apparent influence of geologic effects (topography, depositional environment) on the stresses. 28 refs., 10 figs., 3 tabs.

This paper discusses a new telerobotic control concept which couples human supervisory commands with computer reasoning. The control system is responsive and accomplishes an operator's commands while providing obstacle avoidance and stable controlled interactions with the environment in the presence of communication time delays. This provides a system which not only assists the operator in accomplishing tasks but modifies inappropriate operator commands which can result in safety hazards and/or equipment damage. Research and development of this concept is being carried out in the Telerobotics Research Laboratory at Sandia National Laboratories. 12 refs., 4 figs.

After a decade of photovoltaic system research, most system related issues have been successfully resolved. Current system research activities are now oriented toward maintaining and updating the comprehensive database on system performance established by previous research efforts, integrating new components into system designs, and transferring the accumulated information to industry and users of the technology. This paper presents a brief overview of the status of system research in the United States, emphasizing three key activities - field evaluation, balance-of-system hardware development, and technology transfer. 5 refs., 2 tabs.

Over the past decade, Sandia National Laboratories has managed the Department of Energy (DOE)-sponsored programs for the development of the sodium/sulfur battery technology. Two DOE offices have provided support for these programs: the Office of Energy Storage and Distribution (OESD) and the Office of Transportation Systems (OTS). The ultimate goal of these ongoing efforts is to develop and demonstrate high performance, cost-effective systems suitable for both stationary and mobile applications. A part of Sandia's responsibility is to evaluate the status of the technologies and to address specific problems that are encountered during the development process. The number and level of effort devoted to these tasks are scaled such that the funding emphasis is given to the contracted engineering development programs. Two of the major safety-related concerns with sodium/sulfur EV batteries are the potential consequences associated with large temperature increases and vehicle accidents. The first three tasks represent Sandia's initial effort to help identify effective methods to limit the temperature rise in the battery during both expected and unexpected conditions and to assess one possible result of a vehicle accident. Descriptions of each task along with selected results are given in the following sections. 4 figs., 2 tabs.

With increasing demands on system requirements, designers must look for new alternatives to successfully complete their goals. One alternative that offers designers many benefits is ASICs. They maximize device functionality while minimizing system space. Also as operating frequencies approach gigahertz speeds, ASICs allow specialized placement of functional blocks on chip to minimize propagation delays of the signal. At Sandia, we found these requirements forcing us to look at ASICs fabricated in GaAs.

The supercomputer industry is at a crossroads. While its traditional markets have become relatively mature, the industry is becoming more competitive, especially with the challenge from Japan. The industry can either fight over this stable market or dramatically expand the market. The choice is obvious, but what are these new markets and how to approach them. This paper addresses these issues. First, it explains how the traditional definition of a supercomputer seriously constrains its market. An alternate definition opens up a much larger, emerging market. Second, it describes a market segmentation two barriers preventing customer in these new segments from using supercomputing and describes mechanisms to reduce and/or eliminate these barriers. Third, it discusses the portfolio analysis strategy to determine the markets in these new segments on which to concentrate. Obviously, parts of manufacturing are key targets. Finally, it draws some conclusions in terms of two scenarios -- one which describes a healthy, growing US supercomputer industry, the alternative showing the industry rapidly following the footsteps of the US consumer electronics industry. 6 refs.