Fundamental studies of fusion plasmas (open access)

Fundamental studies of fusion plasmas

The major portion of this program is devoted to critical ICH phenomena. The topics include edge physics, fast wave propagation, ICH induced high frequency instabilities, and a preliminary antenna design for Ignitor. This research was strongly coordinated with the world's experimental and design teams at JET, Culham, ORNL, and Ignitor. The results have been widely publicized at both general scientific meetings and topical workshops including the speciality workshop on ICRF design and physics sponsored by Lodestar in April 1992. The combination of theory, empirical modeling, and engineering design in this program makes this research particularly important for the design of future devices and for the understanding and performance projections of present tokamak devices. Additionally, the development of a diagnostic of runaway electrons on TEXT has proven particularly useful for the fundamental understanding of energetic electron confinement. This work has led to a better quantitative basis for quasilinear theory and the role of magnetic vs. electrostatic field fluctuations on electron transport. An APS invited talk was given on this subject and collaboration with PPPL personnel was also initiated. Ongoing research on these topics will continue for the remainder fo the contract period and the strong collaborations are expected to continue, enhancing …
Date: May 26, 1992
Creator: Aamodt, R. E.; Catto, P. J.; D'Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type: Report
System: The UNT Digital Library
Fundamental studies of fusion plasmas. Annual performance report (open access)

Fundamental studies of fusion plasmas. Annual performance report

The major portion of this program is devoted to critical ICH phenomena. The topics include edge physics, fast wave propagation, ICH induced high frequency instabilities, and a preliminary antenna design for Ignitor. This research was strongly coordinated with the world`s experimental and design teams at JET, Culham, ORNL, and Ignitor. The results have been widely publicized at both general scientific meetings and topical workshops including the speciality workshop on ICRF design and physics sponsored by Lodestar in April 1992. The combination of theory, empirical modeling, and engineering design in this program makes this research particularly important for the design of future devices and for the understanding and performance projections of present tokamak devices. Additionally, the development of a diagnostic of runaway electrons on TEXT has proven particularly useful for the fundamental understanding of energetic electron confinement. This work has led to a better quantitative basis for quasilinear theory and the role of magnetic vs. electrostatic field fluctuations on electron transport. An APS invited talk was given on this subject and collaboration with PPPL personnel was also initiated. Ongoing research on these topics will continue for the remainder fo the contract period and the strong collaborations are expected to continue, enhancing …
Date: May 26, 1992
Creator: Aamodt, R. E.; Catto, P. J.; D`Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type: Report
System: The UNT Digital Library
Measurement of the angular distribution of electrons from W {right arrow} e{nu} decays observed in p pbar collisions at {squareroot}s = 1.8 TeV (open access)

Measurement of the angular distribution of electrons from W {right arrow} e{nu} decays observed in p pbar collisions at {squareroot}s = 1.8 TeV

We present a preliminary measurement of the electron angular distribution parameter {alpha}<sub>2</sub> in W {yields} e{nu} events using data collected by the D0 detector during the 1994-1995 Tevatron run. We compare our results with next-to- leading order perturbative QCD, which predicts an angular distribution of (1±{alpha}<sub>1</sub> cos{theta}* +{alpha}<sub>2</sub> cos²{theta}*), where {theta}* is the angle between the charged lepton and the antiproton in the Collins-Soper frame. In the presence of QCD corrections, the parameters {alpha}<sub>1</sub> and {alpha}<sub>2</sub> become functions of p<sup>W</sup><sub>T</sub> , the W boson transverse momentum. We present the first measurement of {alpha}<sub>2</sub> as a function of p<sup>W</sup><sub>T</sub>. This measurement is of importance, because it provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W mass measurement.
Date: July 26, 1999
Creator: Abbott, B.
Object Type: Article
System: The UNT Digital Library
Interface Characterization Techniques for 304L Stainless Steel Resistance Upset Welds (open access)

Interface Characterization Techniques for 304L Stainless Steel Resistance Upset Welds

In an effort to better characterize and classify austenitic stainless steel resistance upset welds, standard methods have been examined and alternative methods investigated. Optical microscopy yields subjective classification due to deformation obscured bond lines and individual perception. The use of specimen preparations that better reveal grain boundaries aids in substantiating optical information. Electron microscopy techniques produce quantitative information in relation to microstructural constituents. Orientation Imaging Microscopy (OIM) is a relatively new technique for obtaining objective, quantitative information pertaining to weld integrity, i.e., percent grain boundary growth across the interface.
Date: July 26, 1998
Creator: Abeln, Terri G.; Kackenko, E. Jim; Necker, Carl T. & Field, Robert D.
Object Type: Article
System: The UNT Digital Library
A study of the elasticity of Ta at high temperature and pressure (open access)

A study of the elasticity of Ta at high temperature and pressure

The thermodynamic and transport properties of crystals and fluids at high temperature and pressure play a central role in the Earth and planetary sciences as well as in a variety of technologies and constitute a principal probe into the internuclear potential energy function at high density. Observation of surface waves by coherent time-domain optical spectroscopy provides an experimental approach to the determination, in the diamond-anvil high-pressure cell, of the elastic constants and thermal diffusivity of metal crystals as well as the equation of state and thermal transport properties of fluids. The electrical resistivities of metals may also be approximately accessible via the Wiedemann Franz Law. Preliminary results on Ta to pressures of 5.2 GPa are reported here. [Ta, elasticity, sound velocity, thermal diffusivity, equation of state].
Date: August 26, 1998
Creator: Abramson, E H; Brown, J M; Hansen, D W; Ruddle, C M; Slutsky, L J & Zaug, J M
Object Type: Article
System: The UNT Digital Library
Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst (open access)

Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst

The work performed in the program suggests that cobalt catalytic performance is a complex function of crystallite size, crystallite composition, and cobalt-support interaction. These properties are determined by the nature of support, the bimetallic component, the promoters, and the method of preparation. Results so far indicate that the lowest methane selectivity occurs on support No. 8, and the highest activity is obtained on support No. 10. Also, promoters 2 and 3 may help lower the formation of methane. These findings, along with the catalyst knowledge gained during Union Carbide's former contract AC22-84PC70028, will be used to develop a superior cobalt catalyst.
Date: August 26, 1992
Creator: Abrevaya, H.
Object Type: Report
System: The UNT Digital Library
Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst. Technical progress report No. 9, October 1, 1991--December 31, 1991 (open access)

Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst. Technical progress report No. 9, October 1, 1991--December 31, 1991

The work performed in the program suggests that cobalt catalytic performance is a complex function of crystallite size, crystallite composition, and cobalt-support interaction. These properties are determined by the nature of support, the bimetallic component, the promoters, and the method of preparation. Results so far indicate that the lowest methane selectivity occurs on support No. 8, and the highest activity is obtained on support No. 10. Also, promoters 2 and 3 may help lower the formation of methane. These findings, along with the catalyst knowledge gained during Union Carbide`s former contract AC22-84PC70028, will be used to develop a superior cobalt catalyst.
Date: August 26, 1992
Creator: Abrevaya, H.
Object Type: Report
System: The UNT Digital Library
Legislative Prayer and School Prayer: The Constitutional Difference (open access)

Legislative Prayer and School Prayer: The Constitutional Difference

Congressional Research Service (CRS) report entailing the Constitutional difference between legislative prayer and school prayer. Topics include, descriptions of both types of prayer, their distinctions, and a conclusion on the matter.
Date: October 26, 1994
Creator: Ackerman, David M.
Object Type: Report
System: The UNT Digital Library
Legislative Prayer and School Prayer: The Constitutional Difference (open access)

Legislative Prayer and School Prayer: The Constitutional Difference

The Supreme Court's decisions holding government-sponsored prayer in the public schools to violate the First Amendment's establishment clause but prayer in legislative assemblies to be constitutional are sometimes lifted up as contradictory. This report summarizes the relevant decisions and identifies the distinctions the Court has drawn between the two situations.
Date: October 26, 1994
Creator: Ackerman, David M.
Object Type: Report
System: The UNT Digital Library
Final report: Efficient thyratron modulator project (open access)

Final report: Efficient thyratron modulator project

The purpose of this program was to examine methods of increasing the efficiency of producing pulses to drive Klystrons in the 150 MW range. This may include 2 Klystrons in the 75 MW range. Specific methods of interest to improve the pulse efficiency were the use of a circuit to add energy to the tail of the pulse, the use of a bipyrimidal transformer, and the use of gas insulation as a means of improving the pulse shape. These methods were investigated using both thyratron and IGBT switching. The low cost designs developed in this work consisted of low voltage designs which don't require the oil immersion. These designs can be ''hot tuned'' based on the use of simple, tunable inductors.
Date: November 26, 1999
Creator: Adler, R. J.; Richter-Sand, R. J. & Gregg, C. W.
Object Type: Report
System: The UNT Digital Library
Waste status and transaction record summary for the southwest quadrant of the Hanford 200 area (open access)

Waste status and transaction record summary for the southwest quadrant of the Hanford 200 area

This supporting document contains a database of waste transactions and waste status reports for all the waste tanks in the southwest quadrant of the 200 Area of the Hanford Site.
Date: January 26, 1996
Creator: Agnew, S. F.; Duran, T. B.; Ortiz, T. P. & Young, B. L.
Object Type: Report
System: The UNT Digital Library
Caribbean Basin Enhancement Legislation (open access)

Caribbean Basin Enhancement Legislation

Legislation provides Caribbean countries similar tariff benefits as Mexico under the Caribbean and Central American Relief and Economic Stabilization Act. A senate bill provides relief to the hurricane affected countries of Central America. The senate bill is more restrictive than the House bill in the scope of tariff benefits offered.
Date: March 26, 1999
Creator: Ahearn, Raymond
Object Type: Report
System: The UNT Digital Library
[Bifurcations and Patterns in Nonlinear Dissifative Systems] (open access)

[Bifurcations and Patterns in Nonlinear Dissifative Systems]

This report discusses the following topics: Rayleigh-Benard convection with an imposed horizontal flow; Rayleigh-Benard convection in a gas under non-boussinesq conditions; electro- convection in a nematic liquid crystal; and Rayleigh-Benard convection in a nematic liquid crystal. (LSP)
Date: February 26, 1992
Creator: Ahlers, G. & Cannell, D. S.
Object Type: Report
System: The UNT Digital Library
[Bifurcations and Patterns in Nonlinear Dissifative Systems]. Progress Report (open access)

[Bifurcations and Patterns in Nonlinear Dissifative Systems]. Progress Report

This report discusses the following topics: Rayleigh-Benard convection with an imposed horizontal flow; Rayleigh-Benard convection in a gas under non-boussinesq conditions; electro- convection in a nematic liquid crystal; and Rayleigh-Benard convection in a nematic liquid crystal. (LSP)
Date: February 26, 1992
Creator: Ahlers, G. & Cannell, D. S.
Object Type: Report
System: The UNT Digital Library
Characterizing Composition Modulations in InAs/AIAs Short-Period Superlattices (open access)

Characterizing Composition Modulations in InAs/AIAs Short-Period Superlattices

The formation of quantum wires has much interest due to their novel electronic properties which may lead to enhanced optoelectronic device performance and greater photovoltaic efficiencies. One method of forming these structures is through spontaneous lateral modulation found during the epitaxial growth of III/V alloys. In this paper, we report and summarize our investigations on the formation of lateral moduation in the MBE grown InAlAs/InP(001) system. This system was grown as a short-period superlattice where n-monolayers of InAs are deposited followed by m-Monolayers of AlAs (with n and m~2) and this sequence is repeated to grown a low strain InAlAs ternary alloy on InP(001) that exhibits lateral modulation. Films were grown under a variety of condition (growth temperature, effective alloy composition, superlattice period, and growth rate). These films have been extensively analyzed using X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and microcharacterization, in addition to photon-based spectroscopes. Here we present results of several microstructural characterizations using a wide range of TEM-based techniques, and compare them to results from the other methods to obtain a unified understanding of composition modulation. Two strong points consistently emerge: 1) The lateral modulation wavelength is insensitive to growth temperature and effective alloy …
Date: April 26, 1999
Creator: Ahrenkiel, S. P.; Follstaedt, D. M.; Jones, E. D.; Lee, S. R.; Mascarenhas, A.; Mirecki-Millunchick, J. et al.
Object Type: Article
System: The UNT Digital Library
Simulated Impact of Roof Solar Absorptance, Attic, and DuctInsulation, and Climate on Cooling and Heating Energy Use inSingle-Family Resi dential Buildings (open access)

Simulated Impact of Roof Solar Absorptance, Attic, and DuctInsulation, and Climate on Cooling and Heating Energy Use inSingle-Family Resi dential Buildings

This report summarizes a comparative analysis of the impact of roof surface solar absorptance, attic, and duct insulation on simulated residential annual cooling and heating energy use in sixteen sunbelt climates. These locations cover a wide range of climates where cool roofs are expected to save energy and money, and are areas with high growth rates in new residential construction. The residences are single-story, single-family of new construction with either a gas furnace or an electric heat pump, and with ducts in the attic OT conditioned zone. The objective is to demonstrate that a residence with a cool roof could utilize a lower level of attic insulation than one with a dark roof with a zero net change in the annual energy bill. Annual energy use is simulated with DOE-2. lE, which was adapted with a validated residential duct-attic function, for dark and cool roofs and eleven attic insulation R-values ranging from 1 through 60. Analysis of the simulated energy savings from the light-colored roofs show that the savings can be transformed into an equivalent reduction in the level of attic insulation. Reductions in R-value are observed in varying degrees for residences with both gas and electric heat, all duct …
Date: October 26, 1998
Creator: Akbari, H. & Konopacki, S.
Object Type: Report
System: The UNT Digital Library
Software Configuration Management Plan for sample trucks no. 2, 3, and 4 alarm & control logic (open access)

Software Configuration Management Plan for sample trucks no. 2, 3, and 4 alarm & control logic

This document establishes the methods for configuration control of the sample truck alarm and control logic. Responsibility for documentation change control and custody are described.
Date: September 26, 1995
Creator: Akers, J. C. & Dowell, J. L.
Object Type: Report
System: The UNT Digital Library
Subsurface imaging using the spectral polarization difference technique and NIR illumination (open access)

Subsurface imaging using the spectral polarization difference technique and NIR illumination

A subsurface imaging system is utilized to test the ability of the spectral polarization difference imaging technique for deep subsurface imaging in tissues. The illumination of the system is derived from compact class III lasers in the red and NIR spectral region and, alternatively, from a white light source and selection of the appropriate illumination wavelength using band-pass optical filters. The experimental results demonstrate detection and imaging of a high-scattering object located up to 1.5 cm underneath the surface of a host chicken tissue.
Date: January 26, 1999
Creator: Alfano, R R; Demos, S G & Radousky, H B
Object Type: Article
System: The UNT Digital Library
Beam Tilt and Angular Dispersion in Broad-Bandwidth, Nanosecond Optical Parametric Oscillators (open access)

Beam Tilt and Angular Dispersion in Broad-Bandwidth, Nanosecond Optical Parametric Oscillators

We show that the signal and idler beams generated by certain types of unseeded, nanosecond optical parametric oscillators are tilted and angularly dispersed and have anomalously large bandwidths. This effect is demonstrated in both laboratory measurements and a numerical model. We show how the optical cavity design influences the tilts and how they can be eliminated or minimized. We also determine the conditions necessary to injection seed these parametric oscillators.
Date: January 26, 1999
Creator: Alford, W. J.; Arisholm, G.; Gehr, R. J.; Schmitt, R. L. & A.V., Smith.
Object Type: Article
System: The UNT Digital Library
Development of Characterization Tools for Reliability Testing of MicroElectroMechanical System Actuators (open access)

Development of Characterization Tools for Reliability Testing of MicroElectroMechanical System Actuators

Characterization tools have been developed to study the performance characteristics and reliability of surface micromachined actuators. These tools include (1) the ability to electrically stimulate or stress the actuator, (2) the capability to visually inspect the devices in operation, (3) a method for capturing operational information, and (4) a method to extract performance characteristics from the operational information. Additionally, a novel test structure has been developed to measure electrostatic forces developed by a comb drive actuator.
Date: July 26, 1999
Creator: Allen, James J.; Eaton, William P.; Smith, Norman F. & Tanner, Danelle M.
Object Type: Article
System: The UNT Digital Library
Slip, Twinning and Transformation in Laves Phases. Technical Progress Report, August 1, 1990--July 31, 1993 (open access)

Slip, Twinning and Transformation in Laves Phases. Technical Progress Report, August 1, 1990--July 31, 1993

Research was concentrated on two-phase Ti-TiCr{sub 2} alloys, two- phase Fe-ZrFe{sub 2} alloys, and two-phase ternary Ni-Cu-Mg alloys containing MgNi{sub 2} and MgCu{sub 2} phases. Work demonstrated that a variety of room-temperature deformation processes are possible in Laves phases. A strain-induced phase transformation from C36{r_arrow}C15 structures is one mechanism for plastic deformation in ZrFe{sub 2}. The C15 structure in TiCr{sub 2} deforms by slip and twinning. The microstructure after indentation of specimens containing C36 phases ZrFe{sub 2} and MgNi{sub 2} indicates that a variety of slip systems operate in this form. 8 figs.
Date: January 26, 1993
Creator: Allen, S. M. & Livingston, J. D.
Object Type: Report
System: The UNT Digital Library
Slip, Twinning and Transformation in Laves Phases. [Ti-TiCr[sub 2]; Fe-ZrFe[sub 2]; Ni-Cu-Mg containing MgNi[sub 2] and MgCu[sub 2]] (open access)

Slip, Twinning and Transformation in Laves Phases. [Ti-TiCr[sub 2]; Fe-ZrFe[sub 2]; Ni-Cu-Mg containing MgNi[sub 2] and MgCu[sub 2]]

Research was concentrated on two-phase Ti-TiCr[sub 2] alloys, two- phase Fe-ZrFe[sub 2] alloys, and two-phase ternary Ni-Cu-Mg alloys containing MgNi[sub 2] and MgCu[sub 2] phases. Work demonstrated that a variety of room-temperature deformation processes are possible in Laves phases. A strain-induced phase transformation from C36[r arrow]C15 structures is one mechanism for plastic deformation in ZrFe[sub 2]. The C15 structure in TiCr[sub 2] deforms by slip and twinning. The microstructure after indentation of specimens containing C36 phases ZrFe[sub 2] and MgNi[sub 2] indicates that a variety of slip systems operate in this form. 8 figs.
Date: January 26, 1993
Creator: Allen, S.M. & Livingston, J.D.
Object Type: Report
System: The UNT Digital Library
Novel InGaAsN pn Junction for High-Efficiency Multiple-Junction Solar Cells (open access)

Novel InGaAsN pn Junction for High-Efficiency Multiple-Junction Solar Cells

We report the application of a novel material, InGaAsN, with bandgap energy of 1.05 eV as a junction in an InGaP/GaAs/InGaAsN/Ge 4-junction design. Results of the growth and structural, optical, and electrical properties were demonstrated, showing the promising perspective of this material for ultra high efficiency solar cells. Photovoltaic properties of an as-grown pn diode structure and improvement through post growth annealing were also discussed.
Date: March 26, 1999
Creator: Allerman, A. A.; Chang, P. C.; Gee, J. M.; Hammons, B. E.; Hou, H. Q.; Jones, E. D. et al.
Object Type: Article
System: The UNT Digital Library
Flux effects on defect production and damage accumulation in cu and fe exposed to IFE-like conditions (open access)

Flux effects on defect production and damage accumulation in cu and fe exposed to IFE-like conditions

Radiation damage production and accumulation in solids can be divided into two stages. In the production stage, the impinging particle gradually gives off its kinetic energy to lattice atoms in the form of energetic recoils. These deposit their energy by generating secondary and higher order recoils that result in a displacement collision cascade. The outcome of this stage, of the time scale of a few to 100 picoseconds, is a population of point or clustered defects known as the primary state of damage. In the second stage, which can extend over seconds, defects that survive recombination within their nascent cascade migrate over long distances, interacting with the microstructure. These freely migrating defects (FMD) are responsible for the changes in the macroscopic properties of metals under irradiation, such as void swelling, embrittlement, radiation enhanced diffusion, etc. Such changes in mechanical properties are most often detrimental and severely limit the flexibility in materials choice and operating temperature when designing a fusion power plant. Under most conditions, such as those that would be present in a magnetic fusion energy plant, or when bombarding with fission or spallation neutrons, irradiation takes place at a certain dose rate and temperature, but in a continuous manner. …
Date: August 26, 1999
Creator: Alonso, E. A.; Caturla, M. J.; Diaz de la Rubia, T.; Perlado, J. M. & Stoller, R. E.
Object Type: Article
System: The UNT Digital Library