Ames test results on shot-tank residues (open access)

Ames test results on shot-tank residues

In August 1987, a routine Ames test on soot from the Lawrence Livermore National Laboratory (LLNL) 4-in. gun showed that the soot was mutagenic to Salmonella bacteria. Subsequent liquid chromatography on the soot showed that, out of hundreds of ultravoilet-absorbing compounds found in the residue, only three or four were mutagenic. When a sample large enough to weigh was collected, it was found that No environmentally identified complex mixture has ever been reported with as much Ames/Salmonella activity per gram as the gun residues.'' Since then, Ames tests of hundreds of samples have verified that the residues from our gun tanks may be hazardous to health. The actual degree of the hazard and the identity of the offending chemicals are still unknown. 2 refs.
Date: September 21, 1990
Creator: Bloom, G.H.
Object Type: Article
System: The UNT Digital Library
An analysis of commerical zeolite catalysts by multinuclear NMR (open access)

An analysis of commerical zeolite catalysts by multinuclear NMR

This work involves studying two commercial hydrocracking catalysts by solid state multinuclear NMR silicon 29 and aluminum 27 with the goal of developing a method of determining the fraction zeolite in the catalysts. The zeolite fraction is known to be one of the faujasite zeolites type X or Y. The clay matrix of the catalyst is assumed to be kaolinite. Fresh, air-exposed commercial hydrocracking catalysts were provided by Phillips Petroleum. Sample 33351-86 was known to be a physical mixture of a Y zeolite and a clay matrix. The other catalyst, 33351-20, was composed of a faujasite zeolite grown within a clay matrix. Both were suspected of being about 20 wt % zeolite. Nothing is known about the state of pretreatment or cation exchange. A portion of each catalyst was calcined in a porcelain crucible in air at 500{degree}C for two hours with a hour heating ramp preceding and a two hour cooling ramp following calcination. 64 refs., 21 figs., 8 tabs.
Date: September 21, 1990
Creator: Flanagan, L.
Object Type: Report
System: The UNT Digital Library
Bond and Low Cycle Fatigue Behavior of Thermoset Composite Reinforcing for the Concrete Industry (open access)

Bond and Low Cycle Fatigue Behavior of Thermoset Composite Reinforcing for the Concrete Industry

This thesis encompasses two separate research projects. The first project, described in Chapter 2 was a project investigating the fatigue behavior of thermoset Fiber Composite (FC) sandwich wall ties. The second research project detailed in this thesis was a project studying the bond and tensile properties of FC rod and FC fibers.
Date: September 21, 1990
Creator: Barnes, Bruce
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A characterization of internal-Sn Nb sub 3 Sn superconductors for use in the Proof of Principles (PoP) coil (open access)

A characterization of internal-Sn Nb sub 3 Sn superconductors for use in the Proof of Principles (PoP) coil

High performance Ti-alloyed internal-Sn superconductors have been selected for use in the Proof of Principles (PoP) coil, and a 1.0 m o.d., 0.4 m i.d., solenoid designed to produce fields up to 15 T. The PoP coil, which will use forced-flow Cable-In-Conduit Conductors (CICC), will operate at 4.2 K and moderate levels of conductor strain. Here we report the results of detailed characterizations of two proposed PoP coil Nb{sub 3}Sn 19 subelement superconductor wires of different topology. We have investigated the critical current as a function of applied field, and applied strain. The wires were found to have excellent high field properties, providing a high performance margin for the proposed PoP coil. The field and strain dependence of J{sub c} have been found to compare favorably with predictions from a wire performance model recently developed for Nb{sub 3}Sn superconductors. 5 refs., 6 figs., 2 tabs.
Date: September 21, 1990
Creator: Summers, L. T.; Duenas, A. R.; Karlsen, C. E.; Ozeryansky, G. M. & Gregory, E.
Object Type: Article
System: The UNT Digital Library
Computations of quenching and stability in a CICC (cable-in-conduit conductor) conductor (open access)

Computations of quenching and stability in a CICC (cable-in-conduit conductor) conductor

The quenching and stability behavior of forced-flow helium-cooled, cable-in-conduit conductors (CICC) has been analyzed using a new computer program. This computer analysis code was developed for performing general, transient, thermal analyses on CICCs. The program includes the necessary details for the physical properties of all the constituent materials of such conductors, and accurately models the thermo- and fluid-dynamic behavior of the helium coolant starting from a wide range of initial conditions. It has been applied to a study of the stability and quench behavior of several large-scale conductor options being considered for use in the magnet systems of the International Thermonuclear Experimental Reactor (ITER), and the results will be reported here. 3 refs., 14 figs.
Date: September 21, 1990
Creator: Wong, R.L.
Object Type: Article
System: The UNT Digital Library
A conceptual design of the International Thermonuclear Experimental Reactor for the Central Solenoid (open access)

A conceptual design of the International Thermonuclear Experimental Reactor for the Central Solenoid

Conceptual design of the International Thermonuclear Experimental Reactor (ITER) superconducting magnet system is nearing completion by the ITER Design Team, and one of the Central Solenoid (CS) designs is presented. The CS part of this magnet system will be a vertical stack of eight modules, approximately 16 m high, each having a approximate dimensions of: 4.1-m o.d., 2.8-m i.d., 1.9-m h. The peak field at the bore is approximately 13.5 T. Cable-in-conduit conductor with Nb{sub 3}Sn composite wire will be used to wind the coils. The overall coil fabrication will use the insulate-wind-react-impregnate method. Coil modules will be fabricated using double-pancake coils with all splice joints located in the low-field region on the outside of the coils. All coils will be structurally graded with high-strength steel reinforcement which is co-wound with the conductor. We describe details of the CS coil design and analysis.
Date: September 21, 1990
Creator: Heim, J. R. & Parker, J. M.
Object Type: Article
System: The UNT Digital Library
Electrical Resistivity of Some Zintl Phase and the Precursors (open access)

Electrical Resistivity of Some Zintl Phase and the Precursors

Resistivity measurements have been performed for electric characterization of the compounds Ba{sub 5}Sb{sub 3} and Ba{sub 5}Sb{sub 3}Cl, both with the Mn{sub 5}Si{sub 3} structure type, along with Ca{sub 5}Bi{sub 3} and Ca{sub 5}Bi{sub 3}F, both with the {beta}-Yb{sub 5}Sb{sub 3} structure type. These measurements were taken as a function of temperature using the four probe method on pressed polycrystalline pellets of the compounds. A sealed apparatus was developed for containing these air-sensitive compounds throughout the experiments. By a simple electron count, one extra electron in both Ba{sub 5}Sb{sub 3} and Ca{sub 5}Bi{sub 3} should occupy a conduction band, giving these compounds a metallic character. In the cases of Ba{sub 5}Sb{sub 3}Cl and Ca{sub 5}Bi{sub 3}F, the extra electron should bond to the halide, both filling the valence band and giving rise to semiconducting character. Ca{sub 5}Bi{sub 3}, Ca{sub 5}Bi{sub 3}F, and Ba{sub 5}Sb{sub 3}Cl were found to comply with the electron count prediction. Ba{sub 5}Sb{sub 3}, however, was found to be a semiconductor (E{sub g} = 0.30 eV) with a larger band gap than its corresponding chloride (E{sub g} = 0.09 eV).
Date: September 21, 1990
Creator: Wolfe, Larry
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Electrocatalysis of Anodic and Cathodic Oxygen-Transfer Reactions (open access)

Electrocatalysis of Anodic and Cathodic Oxygen-Transfer Reactions

The electrocatalysis of oxygen-transfer reactions is discussed in two parts. In Part I, the reduction of iodate (IO{sub 3}{sup {minus}}) is examined as an example of cathodic oxygen transfer. On oxide-covered Pt electrodes (PtO), a large cathodic current is observed in the presence of IO{sub 3}{sup {minus}} to coincide with the reduction of PtO. The total cathodic charge exceeds the amount required for reduction of PtO and IO{sub 3}{sup {minus}} to produce an adsorbed product. An electrocatalytic link between reduction of IO{sub 3}{sup {minus}} and reduction of PtO is indicated. In addition, on oxide-free Pt electrodes, the reduction of IO{sub 3}{sup {minus}} is determined to be sensitive to surface treatment. The electrocatalytic oxidation of CN{sup {minus}} is presented as an example of anodic oxygen transfer in Part II. The voltametric response of CN{sup {minus}} is virtually nonexistent at PbO{sub 2} electrodes. The response is significantly improved by doping PbO{sub 2} with Cu. Cyanide is also oxidized effectively at CuO-film electrodes. Copper is concluded to serve as an adsorption site for CN{sup {minus}}. It is proposed that an oxygen tunneling mechanism comparable to electron tunneling does not occur at the electrode-solution interface. The adsorption of CN{sup {minus}} is therefore considered to …
Date: September 21, 1990
Creator: Wels, Brian R.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Electrocatalysis of anodic oxygen-transfer reactions at modified lead dioxide electrodes (open access)

Electrocatalysis of anodic oxygen-transfer reactions at modified lead dioxide electrodes

The electrocatalytic activities were compared for pure and chloride-doped beta-PbO{sub 2} (Cl-PbO{sub 2}) films on gold and platinum substrates. Rate constants were increased significantly for oxidations of Mn{sup 2+}, toluene, benzyl alcohol, dimethylsulphoxide (DMSO) and benzaldehyde in acidic media by the incorporation of Cl{sup {minus}} into the oxide films. These reactions are concluded to occur by the electrocatalytic transfer of oxygen from H{sub 2}O to the reaction products. Results of x-ray diffraction studies indicate the Cl-PbO{sub 2} film continues to have the slightly distorted rutile structure of pure beta-PbO{sub 2}. The observed electrocatalytic phenomena are concluded to be the beneficial consequence of surface defects generated when Cl{sup {minus}} serves for charge compensation within the surface matrix and, thereby, increases the number of surface sites capable of adsorbing hydroxyl radicals which are transferred in the electrocatalytic O-transfer reactions. 91 refs., 44 figs., 10 tabs.
Date: September 21, 1990
Creator: Hsiao, Yun-Lin.
Object Type: Report
System: The UNT Digital Library
Exclusive neutral strange particle production from double Pomeron exchange produced by proton-proton interactions at radical s = 62 GeV (open access)

Exclusive neutral strange particle production from double Pomeron exchange produced by proton-proton interactions at radical s = 62 GeV

Data are presented for the first time on exclusive Pomeron-Pomeron interactions which produce a neutral strange and neutral antistrange particle pair in a central system X. In this paper, the system, X, is identified as one of the following neutral combinations; K{sub s}{sup 0}K{sub s}{sup 0}, K{sub s}{sup 0}K{sup {plus minus}}{pi}{sup {minus plus}}, {Lambda}{sup 0}{bar {Lambda}}{sup 0}, {Lambda}{sup 0}{bar {Lambda}}{sup 0}*. These data were obtained in proton-proton collisions at {radical}s = 62 GeV at the CERN ISR. The triggering systems used to obtain these data are described, followed by a description of the data. The central system mass distributions are presented along with differential mass cross section estimates. A broad enhancement is seen in the K{sub s}{sup 0}K{sub s}{sup 0} system at a mass of 1.2 GeV, and is likely to have the quantum numbers J{sup PC} = 0{sup ++}. Total cross section estimates of 1.3 {plus minus} .64 {mu}b in the K{sub 2}{sup 0}K{sub s}{sup 0} system, . 44 {plus minus} .14 {mu}b in the K{sub s}{sup 0}K{sup {plus minus}}{pi}{sup {minus plus}} system, .20 {plus minus} .14 {mu}b in the {Lambda}{sup 0}{bar {Lambda}}{sup 0} system, and .13 {plus minus} .06 {mu}b in the {Lambda}{sup 0}{bar {Lambda}}{sup 0}* system are …
Date: September 21, 1990
Creator: Skeens, John
Object Type: Thesis or Dissertation
System: The UNT Digital Library
FENIX (Fusion ENgineering International eXperimental): A test facility for ITER (International Thermonuclear Experimental Reactor) and other new superconducting magnets (open access)

FENIX (Fusion ENgineering International eXperimental): A test facility for ITER (International Thermonuclear Experimental Reactor) and other new superconducting magnets

The Fusion ENgineering International eXperimental (FENIX) Test Facility which is nearing completion at Lawrence Livermore National Laboratory, is a 76-t set of superconducting magnets housed in a 4-m-diameter cryostat. It represents a significant step toward meeting the testing needs for the development of superconductors appropriate for large-scale magnet applications such as the International Thermonuclear Experimental Reactor (ITER). The magnet set is configured to allow radial access to the 0.4-m-diameter high-field region where maximum fields up to 14 T will be provided. The facility is fitted with a thermally isolated test well with a port to the high-field region that allows insertion and removal of test conductors without disturbing the cryogenic environment of the magnets. It is expected that the facility will be made available to magnet developers internationally, and this paper discusses its general design features, its construction, and its capabilities.
Date: September 21, 1990
Creator: Slack, D. S.; Patrick, R. E. & Miller, J. R.
Object Type: Article
System: The UNT Digital Library
Fundamental Investigations of Supported Monometallic and Bimetallic Catalysts by Proton Magnetic Resonance Spectroscopy (open access)

Fundamental Investigations of Supported Monometallic and Bimetallic Catalysts by Proton Magnetic Resonance Spectroscopy

Proton magnetic resonance spectroscopy, or nuclear magnetic resonance (NMR) of hydrogen, has been applied to investigate silica-supported Group VIII monometallic and Group VIII-Group IB bimetallic catalysts and alumina- and silica-supported platinum-rhenium bimetallic catalysts. Two adsorbed states of hydrogen, i.e., irreversible and reversible hydrogen, on the surfaces of monometallic Ru, Pt, and Cu particles and bimetallic Ru-Group Ib, Pt-Group Ib, and Pt-Re particles were observed directly via proton NMR. The same amounts of the irreversible hydrogen adsorbed on pure Ru catalysts were measured by both proton NMR and the volumetric technique. The electronic environments on surfaces of monometallic catalysts are sensitive to changes in metal dispersion, state of adsorbed hydrogen, and residual chlorine. Surface compositions for the Ru--Cu and Pt--Cu bimetallic catalysts were determined by NMR of adsorbed hydrogen. 297 refs., 96 figs., 19 tabs.
Date: September 21, 1990
Creator: Wu, Xi
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The growth, structure, and thermal stability of vapor deposited ultra-thin metal films: Rh on Ag(100), Au on Pd(110), and Pt on Pd(110) (open access)

The growth, structure, and thermal stability of vapor deposited ultra-thin metal films: Rh on Ag(100), Au on Pd(110), and Pt on Pd(110)

The growth, structure, and thermal stability of ultra-thin metal films (Rh on Ag(100); Au on Pd(110) and Pt on Pd(110)) is investigated using surface sensitive techniques. The three systems studied present a variety of differing characteristics which can contribute to the growth mode, two-dimensional structure, and thermal stability of the films. The main factors contributing to the differing properties of the three systems presented here are: (1) the different substrate morphologies; (2) the differences in surface free energies between the overlayer and the substrate; (3) the degree of lattice mismatch for a particular system; and (4) the extent of miscibility of the two metals. 200 refs., 38 figs.
Date: September 21, 1990
Creator: Schmitz, P.
Object Type: Report
System: The UNT Digital Library
High precision numerical solutions to electric fields in a radial drift chamber (open access)

High precision numerical solutions to electric fields in a radial drift chamber

A modification to the proportional chamber design makes it possible to achieve 5{mu}m spatial resolution in particle tracking. Achieving this requires knowing exactly what the electric field is in the chamber, and simple approximations to the field are not accurate enough. The operation of the chamber and techniques which accurately evaluate the electric field are discussed.
Date: September 21, 1990
Creator: Faust, Jonathan
Object Type: Report
System: The UNT Digital Library
High-resolution angle-resolved photoemission studies of high Tc superconductor Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 (open access)

High-resolution angle-resolved photoemission studies of high Tc superconductor Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8

An angle-resolved photoemission study of the normal and superconducting states in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} was performed. Measurements in the normal state show bands dispersing through the Fermi level from at least 350 meV below E{sub F}. The Fermi level crossings are consistant with local-density band calculation, including a point calculated to be of Bi-O character. Additional measurements were made where bands crossed the Fermi level between 100 and 250K, along with measurements on an adjacent Pt foil. The Fermi edges of both materials agree to within the noise. Below the Fermi level, the spectra show correlation effects on the form of an increased effective mass. The shape of the spectra can be explained by a lifetime-broadened photohole and secondary electrons. The effective inverse photohole lifetime is linear in energy. A superconducting gap has been measured at a number of points where there is density at the Fermi level in the normal state. By proper modeling, a gap of 24 meV was obtained for all these points, including points of Cu-O and Bi-O character respectively, according to band calculation. The lack of gap anisotropy in the basal plane suggests that pinning in this material is not d-wave pairing.
Date: September 21, 1990
Creator: Liu, Rong
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The interactions of water and perfluorodiethyl ether on Ru(100) (open access)

The interactions of water and perfluorodiethyl ether on Ru(100)

We have studied the interactions of water and perfluorodiethyl ether on Ru(100) in order to model the effects of surface structure and humidity on the bonding and decomposition of perfluoroalkyl ether lubricants with metal surfaces. In order to understand the interactions on Ru(100), we have first investigated the interactions of each of these adsorbates alone on the clean surface. The interactions of water with Ru(100) have been studied using both thermal desorption spectroscopy (TDS) and electron energy loss spectroscopy (EELS). From these studies we conclude that a small amount of water dissociates on this surface (5--10% of a monolayer), but water is adsorbed in a predominantly molecular form on this surface with an increasing degree of hydrogen-bonding with increasing coverage. The effects of hydrogen and oxygen coadsorption on the interactions of water with this surface have also been studied using TDS. Finally, the interactions of coadsorbed water and perfluorodiethyl ether on Ru(100) have been investigated using TDS.
Date: September 21, 1990
Creator: Leavitt, Pam
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Inventory of power plants in the United States 1989. [Contains glossary] (open access)

Inventory of power plants in the United States 1989. [Contains glossary]

This document is prepared annually by the Electric Power Division, Office of Coal, Nuclear, Electric and Alternate Fuels, Energy Information Administration (EIA), US Department of Energy (DOE). The purpose of this publication is to provide year-end statistics about electric generating units in operation and to provide a 10-year outlook of future generating unit additions by electric utilities in the United States (the 50 states and the District of Columbia). Data summarized in this report are useful to a wide audience including Congress, federal and state agencies, the electric utility industry, and the general public. The data presented in this report were assembled and published by the EIA, to fulfill its data collection and dissemination responsibilities as specified in the Federal Energy Administration Act of 1974 (Public Law 93-275) as amended. The report is organized into the following chapters: Summary Statistics; Operable Electric Generating Units; and Projected Electric Generating Unit Additions.
Date: September 21, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
An investigation of the mechanisms of calcination and sulfation in coal-water mixtures (open access)

An investigation of the mechanisms of calcination and sulfation in coal-water mixtures

The purpose of this investigation is to study the mechanisms of sulfur capture when burning coal-water-limestone mixtures (CWLM) in fluidized beds. Special care is taken to make comparisons with to dry coal and sorbent under comparable experimental conditions. A series of experiments were performed in an eight-inch diameter bubbling fluidized bed combustor to address this problem. 33 refs., 17 figs., 5 tabs.
Date: September 21, 1990
Creator: Christofides, N.
Object Type: Report
System: The UNT Digital Library
LIMB demonstration project extension (open access)

LIMB demonstration project extension

The purpose of the DOE limestone injection multistage burner (LIMB) Demonstration Project Extension is to extend the data base on LIMB technology and to expand DOE's list of Clean Coal Technologies by demonstrating the Coolside process as part of the project. The main objectives of this project are: to demonstrate the general applicability of LIMB technology by testing 3 coals and 4 sorbents (total of 12 coal/sorbent combinations) at the Ohio Edison Edgewater plant; and to demonstrate that Coolside is a viable technology for improving precipitator performance and reducing sulfur dioxide emissions while acceptable operability is maintained. Progress is reported. 3 figs.
Date: September 21, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
LIMB Demonstration Project Extension (open access)

LIMB Demonstration Project Extension

The DOE LIMB Demonstration Project Extension is a continuation of the EPA Limestone Injection Multistage Burner (LIMB) Demonstration. EPA ultimately expects to show that LIMB is a low cost control technology capable of producing moderate SO{sub x} and NO{sub x} control (50--60 percent) with applicability for retrofit to the major portion of the existing coal-fired boiler population. The current EPA Wall-Fired LIMB Demonstration is a four-year project that includes design and installation of a LIMB system at the 105-MW Unit 4 boiler at Ohio Edison's Edgewater Station in Lorain, Ohio. LIMB Extension testing continued during the quarter with lignosulfonated hydrated lime, pulverized limestone, and hydrated dolomitic lime while firing 1.8% and 3% sulfur coals. Sulfur dioxide removal efficiencies were equivalent to the results found during EPA, base LIMB testing. Sulfur dioxide removal efficiencies were lower than expected while testing with pulverized limestone without humidification. A slight increase in sulfur capture was noted while injecting pulverized limestone at the 187' elevation and with the humidifier outlet temperature at 145{degree}F.
Date: September 21, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Low-energy electron diffraction investigation of epitaxial growth: Pt and Pd on Pd(100) (open access)

Low-energy electron diffraction investigation of epitaxial growth: Pt and Pd on Pd(100)

We investigate the epitaxial growth of Pt and Pd and Pd(100) via spot profile analysis using conventional low-energy electron diffraction (LEED). We resolve a central-spike and diffuse component in the spot profiles, reflecting the layer-occupations and pair-correlations, respectively. Kinetic limitations inhibit layer-by-layer growth at low temperatures. Our data suggest diffusion switches on at ca. 150 K for Pt and ca. 170 K for Pd indicating activation barriers to surface diffusion of ca. 10 and ca. 13 kcal/mol, respectively. To clarify the role of diffusion in determining the resulting film morphology, we develop a growth model that incorporates the adsorption-site requirement and predicts intensity oscillations. We present a new procedure to experimentally determine out-of-phase scattering conditions. At these energies, ring-structure is evident in the profiles during Pd growth between ca. 200 and 400 K. We report ring intensity oscillations as a function of coverage, which demonstrate the filling of individual layers.
Date: September 21, 1990
Creator: Flynn-Sanders, D.
Object Type: Report
System: The UNT Digital Library
Magnetic and thermal properties of high Tc superconductors (open access)

Magnetic and thermal properties of high Tc superconductors

Measurements of the normal state magnetic susceptibility {chi}(T) of YBa{sub 2}Cu{sub 3}O{sub 7}, Bi{sub 1.8}Pb{sub 0.2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}, and Bi{sub 2{minus}x}Pb{sub x}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+{delta}} (x = 0.2 and 0.25) were carried out. All {chi}(T) data show negative curvature below {approximately}2{Tc}. The data for YBa{sub 2}Cu{sub 3}O{sub 7} are in excellent agreement with a new calculation of the superconducting fluctuation diamagnetism. From the analysis, we infer s-wave pairing and microscopic parameters are obtained. For {chi}(T) of YBa{sub 2}Cu{sub 3}O{sub 7}, part of the negative curvature is inferred to arise from the normal state background. We find a strong temperature dependent anisotropy {delta}{chi} {equivalent to} {chi}{sub c} {minus} {chi}{sub ab} and estimate the normal state spin contributions to {chi}(T). The heat capacity C(T) of YBa{sub 2}Cu{sub 3}O{sub 7} is reported for 0.4 K < T < 400 K in zero and 70 kG magnetic fields. In addition to the feature associated with the onset of the superconductivity at {Tc}, two anomalies in C(T) were observed near 74 K and 330 K, with another possible anomaly near 102 K; the temperatures at which they occur correlate with anomalies in {chi}(T) and ultransonic measurements. The occurrence of the anomaly at {approx …
Date: September 21, 1990
Creator: Lee, Wonchoon
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A model for the prediction of Nb sub 3 Sn critical current as a function of field, temperature, strain, and radiation damage (open access)

A model for the prediction of Nb sub 3 Sn critical current as a function of field, temperature, strain, and radiation damage

Conductors designed for fusion machines must operate at high fields, under large mechanical loads, and in a high neutron flux. Present designs favor the use of Nb{sub 3}Sn with force-cooling by supercritical helium to extract large nuclear and ac loss heat loads. Consequently, the magnet designer must have a good knowledge of the critical current of the superconductor as a function of field, strain, temperature, and radiation damage. Expanding on work by Hampshire, et al. and Ekin, combined with radiation damage studies of Nb{sub 3}Sn, we express the critical field (B{sub c20}) as function of temperature, strain and damage energy (E{sub d}). Similarly, the zero-field critical temperature (T{sub c0}) is expressed as a function of strain and damage energy. The expressions of B{sub c20} and T{sub c0} are combined into a functional form that allows an accurate and consistent estimate of the critical current density at the operating conditions of fusion magnet conductors. 9 refs., 4 figs.
Date: September 21, 1990
Creator: Summers, L. T.; Guinan, M. W.; Miller, J. R. & Hahn, P. A.
Object Type: Article
System: The UNT Digital Library
Neutral technicolor pseudo Goldstone bosons production and QCD (quantum chromodynamics) background at the SSC (Superconducting Super Collider) (open access)

Neutral technicolor pseudo Goldstone bosons production and QCD (quantum chromodynamics) background at the SSC (Superconducting Super Collider)

The production of the neutral technicolor pseudo Goldstone bosons, P{sup 0}{prime}and P{sub 8}{sup 0}{prime}, at large transverse momentum in pp collisions, pp {yields} g(q)P{sup 0}{prime} (P{sub 8}{sup 0}{prime})X has been investigated in reactions at a high energy collider such as the SSC. The major two-body and three-body decay modes in tree diagrams are investigated in detail. The t{bar t} decay channel would dominate both the decays of P{sup 0}{prime} and P{sub 8}{sup 0}{prime} if it is allowed. Otherwise, gg and 3g will be the dominant decay modes unless the mass of the P{sup 0}{prime} and P{sub 8}{sup 0}{prime} are below 40 GeV, where b{bar b} becomes dominant. According to the QCD backgrounds, which we have also investigated in detail in this work, the signal for t{bar t} is much larger than the background and will be the ideal signal for detecting these bosons. However, in the absence of the t{bar t} channel, the {tau}{bar {tau}} mode can be used to identify P{sup 0}{prime} up to m{sub P} = 300 GeV in the transverse momentum range P{sub {perpendicular}} {approx lt} 100 GeV. Similarly, the b{bar b} decay mode can serve us a signal to identify P{sub 8}{sup 0}{prime} up to m{sub …
Date: September 21, 1990
Creator: Kuo, Wang-Chuang
Object Type: Thesis or Dissertation
System: The UNT Digital Library