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Global Hybrid Simulations of Energetic Particle-driven Modes in Toroidal Plasmas
Global hybrid simulations of energetic particle-driven MHD modes have been carried out for tokamaks and spherical tokamaks using the hybrid code M3D. The numerical results for the National Spherical Tokamak Experiments (NSTX) show that Toroidal Alfven Eigenmodes are excited by beam ions with their frequencies consistent with the experimental observations. Nonlinear simulations indicate that the n=2 mode frequency chirps down as the mode moves out radially. For ITER, it is shown that the alpha-particle effects are strongly stabilizing for internal kink mode when central safety factor q(0) is sufficiently close to unity. However, the elongation of ITER plasma shape reduces the stabilization significantly.
Date:
December 14, 2004
Creator:
Fu, G. Y.; Breslau, J.; Fredrickson, E.; Park, W. & Strauss, H. R.
Object Type:
Report
System:
The UNT Digital Library
High-efficiency diffractive x-ray optics from sectioned multilayers
We investigate the diffraction properties of sectioned multilayers in Laue (transmission) geometry, at hard x-ray energies (9.5 and 19.5 keV). Two samples are studied, a 200 period W/Si multilayer of 29 nm d-spacing, and a 2020 period Mo/Si multilayer of 7 nm d-spacing, with cross-section depths ranging from 2 to 17 {micro}m. Rocking curves across the Bragg reflections exhibit well-defined interference fringes originating from the depth of the sample. Efficiencies as high as 70% were obtained. This exceeds the theoretical limit for standard zone plates operating in the multi-beam regime, demonstrating that all of the intensity can be directed into a single diffraction order in small-period structures.
Date:
December 14, 2004
Creator:
Kang, H. C.; Stephenson, G. B.; Liu, C.; Conley, R.; Macrander, A. T.; Maser, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material
Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added as gadolinium-oxide to the UO2 powder, and boron, which is applied as a zirconium-diboride coating on the UO2 pellets using plasma spraying or chemical vapor deposition techniques. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be very costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other manufacturing issues that impact cost and performance are maintaining the correct levels of dosing, the reduction in fuel melting point due to gadolinium-oxide additions, and parasitic neutron absorption at fuel's end-of-life. The goal of the proposed research is to develop an alternative approach that involves incorporation of boron or gadolinium into the outer surface of the fuel cladding material rather than as an …
Date:
December 14, 2004
Creator:
Sridharan, K.; Renk, T.J.; Lahoda, E.J. & Corradini, M.L
Object Type:
Report
System:
The UNT Digital Library
Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory, EMSP Project No. 73836
This project was designed as a broad foundational study of spectral induced polarization (SIP) for characterization of contaminated sites. It encompassed laboratory studies of the effects of chemistry on induced polarization, development of 3D forward modeling and inversion codes, and investigations of inductive and capacitive coupling problems. In the laboratory part of the project a physico-chemical model developed in this project was used to invert laboratory IP spectra for the grain size and the effective grain size distribution of the sedimentary rocks as well as the formation factor, porosity, specific surface area, and the apparent fractal dimension. Furthermore, it was established that the IP response changed with the solution chemistry, the concentration of a given solution chemistry, valence of the constituent ions, and ionic radius. In the field part of the project, a 3D complex forward and inverse model was developed. It was used to process data acquired at two frequencies (1/16 Hz and 1/ 4Hz) in a cross-borehole configuration at the A-14 outfall area of the Savannah River Site (SRS) during March 2003 and June 2004. The chosen SRS site was contaminated with Tetrachloroethylene (TCE) and Trichloroethylene (PCE) that were disposed in this area for several decades till the …
Date:
December 14, 2004
Creator:
Morgan, F. Dale & Sogade, John
Object Type:
Report
System:
The UNT Digital Library
Investigating the Heating of a Potassium-Doped Aluminosilicate Ion Source Using a 1 Micron Laser
The heavy ion fusion (HIF) program is interested in developing a high brightness ion source for high energy density physics (HEDP) experiments. One possible approach to obtaining higher brightness may be to raise the surface temperature of the ion source just prior to extraction. The current ion source material being studied is a layer of potassium-doped aluminosilicate bonded to a tungsten substrate. It is speculated that if the surface temperature of the source is raised above 1200 C (from a steady-state temperature of 900 C) for time periods on the order of 100's of nanoseconds, current densities of greater than 100 mA/cm{sup 2} of ions may be achievable. Typical aluminosilicate sources produce ion current densities (either K+ or Na+ ions) of {approx}10 mA/cm{sup 2} (at 1100 C). A number of heating methods might be possible, including lasers, diode arrays, and flash lamps. Here we assume laser heating. In this preliminary study, we used the LLNL RadHeat code to model the time-temperature history of the surface when hit by laser pulses and illustrate how RadHeat can be used to optimize the surface temperature response. Also of interest is the temperature history of the interface temperature between the ceramic and the metal …
Date:
December 14, 2004
Creator:
Schmitt, R. C.; Meier, W. R.; Kwan, J. W.; Abbott, R. P. & Latkowski, J. F.
Object Type:
Report
System:
The UNT Digital Library
Ion charge state fluctuations in vacuum arcs
Ion charge state distributions of cathodic vacuum arcs have been investigated using a modified time-of-flight method. Experiments have been done in double gate and burst gate mode, allowing us to study both systematic and stochastic changes of ion charge state distributions with a time resolution down to 100 ns. In the double gate method, two ion charge spectra are recorded with a well-defined time between measurements. The elements Mg, Bi, and Cu were selected for tests, representing metals of very different properties. For all elements it was found that large stochastic changes occur even at the limit of resolution. This is in agreement with fast changing arc properties observed elsewhere. Correlation of results for short times between measurements was found but it is argued that this is due to velocity mixing rather than due to cathode processes. The burst mode of time-of-flight measurements revealed the systematic time evolution of ion charge states within a single arc discharge, as opposed to previous measurements that relied on data averaged over many pulses. The technique shows the decay of the mean ion charge state as well as the level of material-dependent fluctuations.
Date:
December 14, 2004
Creator:
Anders, Andre; Fukuda, Kentaro & Yushkov, Georgy Yu
Object Type:
Article
System:
The UNT Digital Library
Low-Temperature Synthesis of Actinide Tetraborides by Solid-State Metathesis Reactions
The synthesis of actinide tetraborides including uranium tetraboride (UB,), plutonium tetraboride (PUB,) and thorium tetraboride (ThB{sub 4}) by a solid-state metathesis reaction are demonstrated. The present method significantly lowers the temperature required to {approx_equal}850 C. As an example, when UCl{sub 4}, is reacted with an excess of MgB{sub 2}, at 850 C, crystalline UB, is formed. Powder X-ray diffraction and ICP-AES data support the reduction of UCl{sub 3}, as the initial step in the reaction. The UB, product is purified by washing water and drying.
Date:
December 14, 2004
Creator:
Lupinetti, Anthony J.; Garcia, Eduardo & Abney, Kent D.
Object Type:
Patent
System:
The UNT Digital Library
Mechanical Property Data for Fiberboard
The 9975 shipping package incorporates a cane fiberboard overpack for thermal insulation and impact resistance. Mechanical properties (tensile and compressive behavior) have been measured on cane fiberboard and a similar wood-based product following short-term conditioning in several temperature/humidity environments. Both products show similar trends, and vary in behavior with material orientation, temperature and humidity. A memory effect is also seen in that original strength values are only partially recovered following exposure to a degrading environment and return to ambient conditions.
Date:
December 14, 2004
Creator:
WILLIAM, daugherty
Object Type:
Article
System:
The UNT Digital Library
National Alliance of Clean Energy Incubator Activities - Final Technical Report
Summary of activity related to development of the Alliance of Clean Energy Business Incubators and incubation services provided to the clean energy sector by the Advanced Technology Development Center at the Georgia Institute of Technology.
Date:
December 14, 2004
Creator:
Chris Downing, P.E.
Object Type:
Report
System:
The UNT Digital Library
Natural Resources: Selected Issues for the 109th Congress
None
Date:
December 14, 2004
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
An nth-order, Gaussian Energy Distribution Model for Sintering
Although it is well known that the rate of sintering is governed by deceleratory kinetics, it is often difficult to fit power-law and nth-order reaction models over broad time-temperature ranges. This work shows that a phenomenological model combining a reaction order with an activation energy distribution can correlate surface area as a function of sintering time and temperature over a greater range of those variables. Qualitatively, the activation energy distribution accounts the dependence of free energy on particle size and material defects, while the reaction order accounts for geometric factors such as a distribution of diffusion lengths. The model is demonstrated for sintering of hydroxyapatite using data of Bailliez and Nzihou (Chem. Eng. J. 98 (2004), 141-152).
Date:
December 14, 2004
Creator:
Burnham, A K
Object Type:
Article
System:
The UNT Digital Library
Oral History Interview with Thomas Loftin, December 14, 2004
The National Museum of the Pacific War presents an oral interview with Thomas Loftin. Loftin joined the Army Air Corps in early 1941. He had flight training at various bases all over Texas and earned his wings and commission in August, 1942. His first assignment was at New Orleans where he flew anti-submarine patrols over the Gulf of Mexico with the 124th Observation Squadron. IN 1944, he became a flight instructor in Florida. In April, 1945, Loftin went overseas to England and was assigned to the 95th Bomb Group with whom he flew on one bomb mission before moving to operations. He returned home in July, 1945 and was training in B-29s when the war ended. Loftin stayed in the Reserves until 1972.
Date:
December 14, 2004
Creator:
Loftin, Thomas W.
Object Type:
Sound
System:
The Portal to Texas History
Oral History Interview with Thomas Loftin, December 14, 2004
The National Museum of the Pacific War presents an oral interview with Thomas Loftin. Loftin joined the Army Air Corps in early 1941. He had flight training at various bases all over Texas and earned his wings and commission in August, 1942. His first assignment was at New Orleans where he flew anti-submarine patrols over the Gulf of Mexico with the 124th Observation Squadron. IN 1944, he became a flight instructor in Florida. In April, 1945, Loftin went overseas to England and was assigned to the 95th Bomb Group with whom he flew on one bomb mission before moving to operations. He returned home in July, 1945 and was training in B-29s when the war ended. Loftin stayed in the Reserves until 1972.
Date:
December 14, 2004
Creator:
Loftin, Thomas W.
Object Type:
Text
System:
The Portal to Texas History
Pakistan-U.S. Relations
A stable, democratic, economically thriving Pakistan is vital to U.S. interests in Asia. Key U.S. concerns regarding Pakistan include regional terrorism; weapons proliferation; the ongoing Kashmir problem and Pakistan-India tensions; human rights protection; and economic development. A U.S.-Pakistan relationship marked by periods of both cooperation and discord was transformed by September 2001 terrorist attacks on the United States and the ensuing enlistment of Pakistan as a pivotal ally in U.S.-led counterterrorism efforts. The top U.S. officials regularly praise Islamabad for its ongoing cooperation, although doubts exist about Islamabad’s commitment to some core U.S. interests in the region.
Date:
December 14, 2004
Creator:
Kronstadt, K. Alan
Object Type:
Report
System:
The UNT Digital Library
Perry Daily Journal (Perry, Okla.), Vol. 111, No. 238, Ed. 1 Tuesday, December 14, 2004
Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.
Date:
December 14, 2004
Creator:
Brown, Gloria
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Position Ring System using Anger Type Detectors
The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.
Date:
December 14, 2004
Creator:
Joel S. Karp, principal investigator
Object Type:
Report
System:
The UNT Digital Library
Public Safety, Interoperability and the Transition to Digital Television
None
Date:
December 14, 2004
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Rains County Leader (Emory, Tex.), Vol. 117, No. 27, Ed. 1 Tuesday, December 14, 2004
Weekly newspaper from Emory, Texas that includes local, state, and national news along with advertising.
Date:
December 14, 2004
Creator:
Hill, Earl Clyde, Jr.
Object Type:
Newspaper
System:
The Portal to Texas History
Record of Technical Change for CAU 5 Landfills, Nevada Test Site, Nevada
Record of Technical Change for Corrective Action Plan for Corrective Action Unit 5: Landfills, Nevada Test Site, Nevada (DOE/NV--986, July 2004).
Date:
December 14, 2004
Creator:
U.S. Department of Energy, National Nuclear Security Administration, Nevada Site Office
Object Type:
Report
System:
The UNT Digital Library
Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium
FLIRE was designed to measure the hydrogen and helium retention and diffusivity in a flowing stream of liquid lithium, and it has accomplished these goals. Retention coefficients for helium in the flowing liquid stream were 0.1-2% for flow speeds of 44 cm/s and implantation energies between 500 and 2000 eV. The energy dependence of retention is linear for the energy range considered, as expected, and the dependence of retention on flow velocity fits the expected square-root of flow speed dependence. Estimates of the helium diffusion coefficient in the flowing lithium stream were {approx} 4 x 10{sup -7} cm{sup 2}/s, and are independent of implantation energy. This value is much lower than expected, which could be due to several factors, such as mixing, bubble formation or surface film formation. In the case of hydrogen, long term retention and release mechanisms are of greatest importance, since this relates to tritium inventory in flowing lithium PFCs for fusion applications. The amount of hydride formation was measured for flowing lithium exposed to neutral deuterium gas. Thermal desorption spectroscopy (TDS) measurements indicate that the hydride concentration was between 0.1 and 0.2% over a wide range of pressures (6.5 x 10{sup -5} to 1 Torr). This …
Date:
December 14, 2004
Creator:
Stubbers, R. A.; Miley, G. H.; Nieto, M.; Olczak, W.; Ruzic, D. N. & Hassanein, A.
Object Type:
Report
System:
The UNT Digital Library
Sapulpa Daily Herald (Sapulpa, Okla.), Vol. 90, No. 79, Ed. 1 Tuesday, December 14, 2004
Daily newspaper from Sapulpa, Oklahoma that includes local, state, and national news along with advertising.
Date:
December 14, 2004
Creator:
Broaddus, Matthew B.
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
The Sealy News (Sealy, Tex.), Vol. 117, No. 100, Ed. 1 Tuesday, December 14, 2004
Semiweekly newspaper from Sealy, Texas that includes local, state, and national news along with advertising.
Date:
December 14, 2004
Creator:
Griffin, Joanie & Horecka, Bobby
Object Type:
Newspaper
System:
The Portal to Texas History
Surface Based Differential Forms
Higher-order basis functions have been constructed for surface-based differential forms that are used in engineering simulations. These surface-based forms have been designed to complement the volume-based forms present in EMSolve[1], a finite element code. The basis functions are constructed on a reference element and transformed, as necessary, for each element in space. Lagrange polynomials are used to create the basis functions. This approach is a necessary step in creating a hybrid finite-element/integral-equation time-domain code for electromagnetic analysis.
Date:
December 14, 2004
Creator:
Pingenot, J.; Yang, C.; Jandhyala, V.; Champagne, N.; White, D.; Stowell, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Texas Attorney General Opinion: GA-0282
Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification: Whether the Texas Real Estate Commission may establish by rule minimum service standards for a real estate broker who enters into an exclusive agency relationship with a party to a real estate transaction (RQ-0224-GA)
Date:
December 14, 2004
Creator:
Texas. Attorney-General's Office.
Object Type:
Text
System:
The Portal to Texas History