A simplified, rugged VISAR (Velocity Interferometer System for Any Reflector) system has been developed using a non-removable delay element and an essentially non-adjustable interferometer cavity. In this system, the critical interference adjustments are performed during fabrication of the cavity, freeing the user from this task. Prototype systems are easy to use and give extremely high quality results. 6 refs., 7 figs.
The High-Temperature Borehole Televiewer is a downhole instrument which provides acoustic pictures of the borehole walls that are suitable for casing inspection and fracture detection in geothermal wells. The Geothermal Drilling Organization has funded the development of a commercial tool survivable to temperatures up to 275{degree}C and pressures of 5000 psi. A real-time display on an IBM-compatible PC was included as part of the developmental effort. This paper describes the three principal components are: the mechanical section, the electronics, and the computer software and hardware. Each of these three components are described with special attention to important design changes most pertinent to a high temperature environment. The results of two field tests of the televiewer system are also described. 7 refs., 4 figs.
Early attempts at estimation of stress wave damage in blasting by use of finite element analysis met with limited success due to numerical instabilities that prevented calculations from being carried to late times after significant fragmentation had occurred. A new damage model based on microcrack growth in tension allows finite element calculations which remain stable at late times. Estimation of crater profiles for blasting experiments in granite, using laboratory properties for all parameters, demonstrate a high level of success for this damage model. However, estimated crater profiles show systematic differences from excavated crater profiles which motivate further developments of this model. 19 refs., 16 figs.
Borated stainless steel tensile testing is being conducted at Sandia National Laboratories (SNL). The goal of the test program is to provide data to support a code case inquiry to the ASME Boiler and Pressure Vessel Code, Section 3. The adoption by ASME facilitates a materials qualification for structural use in transport cask applications. The borated stainless steel being tested conforms to ASTM specification A-887, which specifies 16 grades of material as a function of boron content (0.20% to 2.25%) and fabrication technique. For transport cask basket applications, the potential advantage to using borated stainless steel arises from the fact that the structural and criticality control functions can be combined into one material. The test program at SNL involves procuring material, machining test specimens, and conducting the tensile tests. From test measurements obtained so far, general trends indicate that tensile properties (yield strength and ultimate strength) increase with boron content and are in all cases superior to the minimum required properties established in SA-240, Type 304, a typical grade of austenitic stainless steel. Therefore, in a designed basket, web thickness using borated stainless steel would be comparable to or thinner than an equivalent basket manufactured from a typical stainless steel without boron additions. 3 figs., 5 tabs.
The use of a negative coefficient of thermal expansion (CTE) mineral filler ({beta}-eucryptite) is examined as a means of reducing CTE of a bismaleimide polymer (Kerimid 601). Results show that {beta}-eucryptite is effective in lowering CTE of the polymer and of glass fabric composites with a filled matrix phase. A theoretical model is presented that effectively predicts CTE of the filled BMI but underestimates the observed results by approximately 15%. The lower predicted CTE is believed to be due to poor interfacial adhesion at the {beta}-eucryptite/bismaleimide interface. Poor interfacial adhesion is supported by ultimate tensile strength results. 27 refs., 7 figs., 3 tabs.
Diffusion-limited (heterogeneous) oxidation effects are often important for studies of polymer degradation. Such effects are common in polymers subjected to ionizing radiation at relatively high dose rate. To better understand the underlying oxidation processes and to aid in the planning of accelerated aging studies, it would be desirable to be able to monitor and quantitatively understand these effects. In this paper, we briefly review a theoretical diffusion approach which derives model profiles for oxygen surrounded sheets of material by combining oxygen permeation rates with kinetically based oxygen consumption expressions. The theory leads to a simple governing expression involving the oxygen consumption and permeation rates together with two model parameters {alpha} and {beta}. To test the theory, gamma-initiated oxidation of a sheet of commercially formulated EPDM rubber was performed under conditions which led to diffusion-limited oxidation. Profile shapes from the theoretical treatments are shown to accurately fit experimentally derived oxidation profiles. In addition, direct measurements on the same EPDM material of the oxygen consumption and permeation rates, together with values of {alpha} and {beta} derived from the fitting procedure, allow us to quantitatively confirm for the first time the governing theoretical relationship. 17 refs., 3 figs.
This paper will focus on the electronic and photochemical properties of polysilylenes, with particular emphasis on the many resemblances in the electronic properties of polysilylenes to those of the familiar {pi}-conjugated polymers. In this context, the term {sigma}-conjugation'' will appear in this paper, as it is almost universally prevalent in the field. However, the use of this term should only be interpreted to suggest a correspondence in the electronic properties with those of {pi}-conjugated materials. No direct correspondence in electronic interactions at the atomic level is implied. In fact, the theoretical underpinnings of the mechanism of electron delocalization in {sigma}-bonded systems remain incomplete, at best. The systematic name polysilylene'' will be used in place of the equivalent and widely used term polysilane.'' In this context, these terms are intended to refer to polydiorganosilylenes, i.e. silicon backbones having substituents other than hydrogen. Moreover, since, with the exception of the commercial use of the intractable polydimethylsilylene as a precursor to {beta}-Sic fibers, the overwhelming majority of the interest in the field is in soluble polysilylenes, the discussion here will be of that greatly predominant group of the materials which are fully tractable and processible. 75 refs., 4 figs., 2 tabs.
We have demonstrated that CI{sub 2} RIBE is a useful dry-etch technology for InSb and InAsSb/InSb Strained-Layer Superlattices (SLSs) in spite of the low vapor pressure of the In chlorides. Etching of these materials using both Cl{sub 2} Reactive-Ion-Beam Etching (RIBE) and Ar IBE resulted in extremely smooth surfaces and well controlled etch rates with CI{sub 2} RIBE accelerating the etch rate by approximately a factor of two compared to Ar IBE over the range of beam energies studied. Sloped sidewalls resulted at all tested Cl{sub 2} RIBE energies and are probably caused by sidewall passivation with In chlorides. The anisotropy and reduced etch-induced damage of Cl{sub 2} RIBE is expected to become of critical importance in the fabrication of dense arrays of long-wavelength photodetectors. 2 figs.
A sol-gel method was use to prepare bulk, closed pore, amorphous alumina-silica. Films prepared from this 47wt% Al{sub 2}O{sub 3}- SiO{sub 2} composition were examined by SAW, elipsometry and electrical measurements. The films were found to have a surface area of 1.1 cm{sup 2}/cm{sup 2}, a refractive index of 1.44 at 633 nm, and a relative permittivity of 6.2 at 200 KHz. These properties indicate potential applications as hermetic seals, barrier coatings, dielectric layers for capacitors and passivation coatings for electronic circuits.
We report on the rapid thermal processing (RTP) of Y-123 fibers with and without presintering to form the orthorhombic phase. We show that fibers which were originally semiconducting and tetragonal before rapid thermal processing form normal twinned orthorhombic material after processing for 2--4 seconds at > 1000{degrees}C with a 3 min. cool down in oxygen. They subsequently show {Tc} to 90K and magnetization indicative of substantial diamagnetic shielding. We present the effects of varying the RTP parameters on the morphology, phase, and superconducting properties of a number of tetragonal and orthorhombic Y-123 fibers. 2 refs., 5 figs., 1 tab.
There has long been a need for fast read nonvolatile, rad hard memories for military and space applications. Recent advances in EEPROM technology now allow this need to be met for many applications. Harris/Sandia have developed a 16k and a 256k rad hard EEPROM. The EEPROMs utilize a Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) memory transistor integrated into a 2 {mu}m, rad hard two level metal CMOS process. Both the 16k and the 256k parts have been designed to interface with the Intel 8085 or 80C51 and National 32000 series microprocessors and feature page and block clear modes. Both parts are functionally identical, and are produced by the same fabrication process. They are also pin for pin compatible with each other, except for the extra address and ground pins on the 256k. This paper describes the characteristics of this EEPROM family. 1 ref.
The concentrations of carbon dioxide, methane, sulfur dioxide, nitrous oxides and chlorofluorocarbons is increasing in the earth's atmosphere. Increased concentrations of these trace gases could lead to global warming, increased acid rain and increased UV radiation on the earth's surface; however, the actual impacts are still uncertain and are also the subject of great debate. Application of clean'' energy sources such as geothermal are obviously desirable for decreasing these effects and improving our overall general environment. This paper briefly summarizes the global environment concerns, providing a backdrop for the following papers which describe the geothermal role in future environmental considerations. 5 refs., 2 figs., 1 tab.
Many of the applications that require the unique capabilities of Photoconductive Semiconductor Switches (PCSS) demand a compact package. We have been able to demonstrate that GaAs switches operated in the high gain mode called lock-on'' meet the required electrical switching parameters of several such applications using small switch sizes. The only light source that has enough power to trigger a PCSS and is compatible with a small package is a laser diode. This paper will describe the progress that leads to the triggering of high power PCSS switches with laser diodes. Our goal is to switch up to 5 kA in a single shot mode and up to 100 MW repetitively at up to 10 kHz. These goals are feasible since the switches can be used in parallel or in series. Low light level triggering became possible after the discovery of a high electric field, high gain switching mode in GaAs (and later in InP). At electric fields below 3 kV/cm GaAs switches are activated by creation of, at most, only one conduction electron- valence hole pair per photon absorbed in the sample. This linear mode demands high laser power and, after the light is extinguished, the carriers live for only a few nanoseconds. At higher electric fields GaAs behaves as a light activated Zener diode. The laser light generates carriers as in the linear mode and the field induces gain such that the amount of light required to trigger the switch is reduced by a factor of up to 500. The gain continues until the field across the sample drops to a material dependent lock-on field. At this point the switch will carry as much current as, and for as long as, the circuit can maintain the lock-on field. The gain in the switch allows for the use of laser diodes. 8 refs., 11 figs.
Experimental laminar condensation heat transfer data is reported for fluids with Stefan number up to 3.5. The fluid is a member of a family of fluorinated fluids developed in the last decade which have been extensively used in the electronics industry for soldering, cooling, and testing applications. Experiments were performed by suddenly immersing cold copper spheres in the saturated vapor of this fluid, and heat transfer rates were calculated using the quasi-steady temperature response of the spheres. In these experiments, the difference between saturation and wall temperature varied from 0.5{degree}C to 190{degree}C. Over this range of temperature difference, the condensate properties vary significantly. For example, viscosity of the condense varies by a factor of over 50. Corrections for the temperature dependent properties of the condensate therefore were incorporated in calculating the Nusselt number based on the average heat transfer coefficient. The results are discussed in light of past experimental data theory for Stefan number less than 1. To the knowledge of the authors, this is the first reported study of condensation heat transfer for Stefan number greater that unity. 24 refs., 7 figs., 2 tabs.
A method is presented for determining the force spectral density function for a vibration test where a combination of force and acceleration is used for control. First the acceleration spectral density is established based on an envelope of the interface motion between the test item and the mounting structure (the base) in the use (field) environment. The driving point accelerance (acceleration/force) of the test item is measured at the mounting interface. The force required to drive the test item in an acceleration controlled test is then estimated. A force spectral density is then established using the estimated motion controlled force, and a derived force reduction factor. An extremal control vibration test is then performed based on which parameter (input force or input acceleration) reaches based on which parameter (input force or input acceleration) reaches its envelope first. 7 refs., 7 figs., 2 tabs.
This paper presents the results of an experimental study of the thermal stability in air and vacuum of the codeposited carbon/hydrogen layer formed in a carbon-lined fusion reactor. Results are also presented for the stability of the saturated layer formed by the implantation of energetic hydrogen ions into a graphite surface. For both films, the hydrogen isotope release occurs at a much lower temperature in air than it does in a vacuum. At temperatures above 600 K, the hydrogen isotope release in air is very rapid and is emitted in a condensible form. It is speculated that isotopic exchange with the water present in air is responsible for this release. In vacuum, temperatures in excess of 1000 K are required to produce a rapid release from either film. The implications of these results to the safety of tritium in carbon-lined fusion reactors are discussed. 24 refs., 2 figs.
Laboratory deformation and permeability measurements have been made on chalk samples from Ekofisk area fields as a function of confining stress and pore pressure to determine the effective stress laws for chalk. An understanding of the effective stress law is essential to obtain correct reservoir-property data from core analysis and is critical for reservoir management studies and reservoir compaction models. A powerful statistical technique known as the response surface method has been used to analyze our laboratory data determine the form of the effective stress law for deformation and permeability. Experiments were conducted on chalk samples that had a range of porosities from 15% to 36%, because porosity is the dominant intrinsic property that effects deformation and permeability behavior of chalk. Deformation of a 36% porosity chalk was highly nonlinear, but the effective stress law was linear, with {alpha} equal to about unity. Lower-porosity samples showed linear strain behavior and a linear effective stress law with {alpha} as low as 0.74. Analysis of the effective stress law for permeability is presented only for the lowest porosity chalk sample because changes in permeability in the higher-porosity chalk samples due to increasing confining stress or pore pressure were not were large enough, to deduce meaningful effective stress relationships. 15 refs., 8 figs., 2 tabs.
In actual circuit application, MOS transistor bias is generally not constant through radiation exposure. Nevertheless, the overwhelming majority of radiation effects studies and hardness assurance testing is performed at constant bias for simplicity and practicality. In the past 15 years, however, it has been shown that oxide- and interface-trap charge buildup and annealing during switched-bias exposures can differ quantitatively and qualitatively from that observed during steady-state exposures. This has made it difficult to develop predictive models of MOS circuit response for actual use conditions, and has introduced uncertainty into hardness assurance testing of MOS circuits. In this summary, defect growth and annealing rates are compared for steady-state and switched-biased irradiations of MOS transistors. A simple method is described to predict MOS oxide-trap charge, interface-trap charge, and mobility degradation during switched-bias exposures from steady-state ( on'' and off'') irradiations. Over a wide range of switching conditions for the devices examined, this method has provided predictions typically accurate to within better than 20%. The maximum error observed to data is less than 40%. This method should allow the total-dose radiation response of MOS circuits in real-use scenarios to be modeled with improved accuracy and flexibility. 9 refs., 3 figs.
Drillhole H-16 is an exploratory test hole, 850.9 ft deep, drilled in eastern Eddy County, New Mexico, to study the hydrologic parameters of possible aquifers and how these aquifers could affect the construction and maintenance of a shaft to be located about 54 ft from the drillhole. This shaft will connect the underground working of the WIPP (Waste Isolation Pilot Plant) site to the surface. Oeophysical logs were taken to measure acoustic velocities, density, radioactivity, porosity, and formation resistivities. This report describes the data collected during the drilling of exploration drillhole H-16. 2 refs., 2 figs., 3 tabs.
Recent legislation mandated the improvement of national competitiveness as a mission of the defense programs of the US Department of Energy. As a consequence, technology transfer --- the process of transferring commercially valuable technologies developed under government sponsorship to industry for commercialization --- is becoming an important emphasis at many DOE laboratories. Technology transfer processes take many forms, and there are different perspectives on how to approach this activity. In this paper, a taxonomy of technology transfer processes at a national laboratory is presented. In addition, the focus and rationale of Sandia National Laboratories' unique new initiative called the Technology Maturation Program is discussed. This program is designed to complete one essential element of technology transfer that advanced technologies toward commercial applications to the point that industry is willing to assume the investment risk. Strategies and program plans designed to improve the effectiveness of Sandia's contribution to enhancing US industry's competitive position in world markets are also presented.
ENDF/B-VI cross sections were released to the testing community in January 1990. Work at Sandia National Laboratories, with pre-released versions of the new cross sections indicates that changes in the neutron-induced charged-particle reactions will significantly affect 14-MeV neutron dosimetry. Reactions that are important for fission reactor dosimetry were examined and most did not change significantly. 12 refs., 3 figs., 3 tabs.
We have systematically varied processing parameters to fabricate PZT 53/47 thin films. Polycrystalline PZT thin films were fabricated by spin depositing Pt coated SiO{sub 2}/Si substrates with alkoxide solutions. Our study focused on two process parameters: (1) heating rate and (2) excess Pb additions. We used rapid thermal processing techniques to vary heating rates from 3{degree}C/min to 8400{degree}C/min. Films were characterized with the following excess Pb additions: 0, 3, 5, and 10 mol %. For all process variations, films with greater perovskite content had better ferroelectric properties. Our best films were fabricated using the following process parameters: an excess Pb addition of 5 mol %, a heating rate of 8400{degree}C/min and annealing conditions of 700{degree}C for 1 min. Films fabricated using these process conditions had a remanent polarization of 0.27 C/m{sup 2} and a coercive field of 3.4 MV/m. 12 refs., 4 figs.
Lost circulation is the phenomenon where circulating drilling fluid is lost to fractures or pores in the rock formation rather than returning to the surface through the wellbore annulus. In geothermal drilling, lost circulation can be a serious problem that contributes greatly to the cost of the average geothermal well. A DOE-sponsored program is underway at Sandia National Laboratories to develop new technology for solving lost circulation problems. The Lost Circulation Technology Development Program currently consists of twelve projects in three areas: technology to plug porous and minor-fracture loss zones; technology to plug major-fracture loss zones; and technology to characterize loss zones. This paper describes the program and highlights recent progress. 12 refs., 10 figs.