Investigating the Heating of a Potassium-Doped Aluminosilicate Ion Source Using a 1 Micron Laser (open access)

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
Surface Based Differential Forms (open access)

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
Position Ring System using Anger Type Detectors (open access)

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
A viable supersymmetric model with UV insensitive anomaly mediation (open access)

A viable supersymmetric model with UV insensitive anomaly mediation

We propose an electroweak model which is compatible with the UV insensitive anomaly mediated supersymmetry breaking. The model is an extension of the NMSSM by adding vector-like matter fields which can drive the soft scalar masses of the singlet Higgs field negative and the successful electroweak symmetry breaking is achieved. Viable parameter regions are found to preserve perturbativity of all the coupling constants up to the Planck scale. With this success, the model becomes a perfect candidate of physics beyond the standard model without the FCNC and CP problem. The cosmology is also quite interesting. The lightest neutralino is the wino which is a perfect cold dark matter candidate assuming the non-thermal production from the gravitino decay. There is no gravitino problem because it decays before the BBN era, and thus the thermal leptogenesis works. The cosmological domain wall problem inherent in the NMSSM is absent since the Z_3 symmetry is broken by the QCD instanton effect in the presence of the vector-like quarks. We also briefly comment on a possible solution to the strong CP problem a la the Nelson-Barr mechanism.
Date: December 14, 2004
Creator: Ibe, Masahiro; Kitano, Ryuichiro & Murayama, Hitoshi
Object Type: Article
System: The UNT Digital Library
A Component Architecture for High-Performance Scientific Computing (open access)

A Component Architecture for High-Performance Scientific Computing

The Common Component Architecture (CCA) provides a means for software developers to manage the complexity of large-scale scientific simulations and to move toward a plug-and-play environment for high-performance computing. In the scientific computing context, component models also promote collaboration using independently developed software, thereby allowing particular individuals or groups to focus on the aspects of greatest interest to them. The CCA supports parallel and distributed computing as well as local high-performance connections between components in a language-independent manner. The design places minimal requirements on components and thus facilitates the integration of existing code into the CCA environment. The CCA model imposes minimal overhead to minimize the impact on application performance. The focus on high performance distinguishes the CCA from most other component models. The CCA is being applied within an increasing range of disciplines, including combustion research, global climate simulation, and computational chemistry.
Date: December 14, 2004
Creator: Bernholdt, D. E.; Allan, B. A.; Armstrong, R.; Bertrand, F.; Chiu, K.; Dahlgren, T. L. et al.
Object Type: Article
System: The UNT Digital Library
Assessing Terrorist Motivations for Attacking Critical "Chemical" Infrastructure (open access)

Assessing Terrorist Motivations for Attacking Critical "Chemical" Infrastructure

Certain types of infrastructure--critical infrastructure (CI)--play vital roles in underpinning our economy, security, and way of life. One particular type of CI--that relating to chemicals--constitutes both an important element of our nation's infrastructure and a particularly attractive set of potential targets. This is primarily because of the large quantities of toxic industrial chemicals (TICs) it employs in various operations and because of the essential economic functions it serves. This study attempts to minimize some of the ambiguities that presently impede chemical infrastructure threat assessments by providing new insight into the key motivational factors that affect terrorist organizations propensity to attack chemical facilities. Prepared as a companion piece to the Center for Nonproliferation Studies August 2004 study--''Assessing Terrorist Motivations for Attacking Critical Infrastructure''--it investigates three overarching research questions: (1) why do terrorists choose to attack chemical-related infrastructure over other targets; (2) what specific factors influence their target selection decisions concerning chemical facilities; and (3) which, if any, types of groups are most inclined to attack chemical infrastructure targets? The study involved a multi-pronged research design, which made use of four discrete investigative techniques to answer the above questions as comprehensively as possible. These include: (1) a review of terrorism and threat …
Date: December 14, 2004
Creator: Ackerman, G.; Bale, J. & Moran, K.
Object Type: Report
System: The UNT Digital Library
Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material (open access)

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
Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium (open access)

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
An nth-order, Gaussian Energy Distribution Model for Sintering (open access)

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
National Alliance of Clean Energy Incubator Activities - Final Technical Report (open access)

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
GAP Final Technical Report 12-14-04 (open access)

GAP Final Technical Report 12-14-04

The Genomics Annotation Platform (GAP) was designed to develop new tools for high throughput functional annotation and characterization of protein sequences and structures resulting from genomics and structural proteomics, benchmarking and application of those tools. Furthermore, this platform integrated the genomic scale sequence and structural analysis and prediction tools with the advanced structure prediction and bioinformatics environment of ICM. The development of GAP was primarily oriented towards the annotation of new biomolecular structures using both structural and sequence data. Even though the amount of protein X-ray crystal data is growing exponentially, the volume of sequence data is growing even more rapidly. This trend was exploited by leveraging the wealth of sequence data to provide functional annotation for protein structures. The additional information provided by GAP is expected to assist the majority of the commercial users of ICM, who are involved in drug discovery, in identifying promising drug targets as well in devising strategies for the rational design of therapeutics directed at the protein of interest. The GAP also provided valuable tools for biochemistry education, and structural genomics centers. In addition, GAP incorporates many novel prediction and analysis methods not available in other molecular modeling packages. This development led to signing …
Date: December 14, 2004
Creator: Andrew J. Bordner, PhD, Senior Research Scientist
Object Type: Report
System: The UNT Digital Library
Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large and Small Atwood Numbers (open access)

Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large and Small Atwood Numbers

This project has two major tasks: Task 1. The construction of a new air/helium facility to collect detailed measurements of Rayleigh-Taylor (RT) mixing at high Atwood number, and the distribution of these data to LLNL, LANL, and Alliance members for code validation and design purposes. Task 2. The collection of initial condition data from the new Air/Helium facility, for use with validation of RT simulation codes at LLNL and LANL. Also, studies of multi-layer mixing with the existing water channel facility. Over the last twelve (12) months there has been excellent progress, detailed in this report, with both tasks. As of December 10, 2004, the air/helium facility is now complete and extensive testing and validation of diagnostics has been performed. Currently experiments with air/helium up to Atwood numbers of 0.25 (the maximum is 0.75, but the highest Reynolds numbers are at 0.25) are being performed. The progress matches the project plan, as does the budget, and we expect this to continue for 2005. With interest expressed from LLNL we have continued with initial condition studies using the water channel. This work has also progressed well, with one of the graduate Research Assistants (Mr. Nick Mueschke) visiting LLNL the past two …
Date: December 14, 2004
Creator: Malcolm J. Andrews, Ph.D.
Object Type: Report
System: The UNT Digital Library
Mechanical Property Data for Fiberboard (open access)

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
Record of Technical Change for CAU 5 Landfills, Nevada Test Site, Nevada (open access)

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
Top physics: search for anomalous kinematics in t anti-t dilepton events at cdf ii (open access)

Top physics: search for anomalous kinematics in t anti-t dilepton events at cdf ii

We report on a search for anomalous kinematics of t{bar t} dilepton events in p{bar p} collisions at {radical}s = 1.96 TeV using 193 pb{sup -1} of data collected with the CDF II detector. We developed a new a priori technique designed to isolate the subset in a data sample revealing the largest deviation from standard model (SM) expectations and to quantify the significance of this departure. In the four-variable space considered, no particular subset shows a significant discrepancy and we find that the probability of obtaining a data sample less consistent with the SM than what is observed is 1.0-4.5%.
Date: December 14, 2004
Creator: Acosta, D.
Object Type: Report
System: The UNT Digital Library
Ultrasonic Examination of Double-Shell Tank 241-AP-106. Examination Completed November 2004 (open access)

Ultrasonic Examination of Double-Shell Tank 241-AP-106. Examination Completed November 2004

COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic nondestructive examination of selected portions of Double-Shell Tank 241-AP-106. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-AP-106 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-22571 (Jensen 2004) and summarized on page 1 of this document, are reported to CH2M Hill and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M Hill, all data is to be recorded on disk and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report that describes the results of the COGEMA ultrasonic examinations.
Date: December 14, 2004
Creator: Pardini, Allan F. & Posakony, Gerald J.
Object Type: Report
System: The UNT Digital Library
High-efficiency diffractive x-ray optics from sectioned multilayers (open access)

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
A Generalized Fast Frequency Sweep Algorithm for Coupled Circuit-EM Simulations (open access)

A Generalized Fast Frequency Sweep Algorithm for Coupled Circuit-EM Simulations

An Asymptotic Wave Expansion (AWE) technique is implemented into the EIGER computational electromagnetics code. The AWE fast frequency sweep is formed by separating the components of the integral equations by frequency dependence, then using this information to find a rational function approximation of the results. The standard AWE method is generalized to work for several integral equations, including the EFIE for conductors and the PMCHWT for dielectrics. The method is also expanded to work for two types of coupled circuit-EM problems as well as lumped load circuit elements. After a simple bisecting adaptive sweep algorithm is developed, dramatic speed improvements are seen for several example problems.
Date: December 14, 2004
Creator: Ouyang, G.; Jandhyala, V.; Champagne, N.; Sharpe, R.; Fasenfest, B. J. & Rockway, J. D.
Object Type: Report
System: The UNT Digital Library
Ion charge state fluctuations in vacuum arcs (open access)

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
Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory, EMSP Project No. 73836 (open access)

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
Low-Temperature Synthesis of Actinide Tetraborides by Solid-State Metathesis Reactions (open access)

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
Global Hybrid Simulations of Energetic Particle-driven Modes in Toroidal Plasmas (open access)

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
Advancing Climate and Carbon Simulation (open access)

Advancing Climate and Carbon Simulation

We use a recently developed integrated climate/carbon model to perform breakthrough studies of the climate. Two major studies are carried out--namely the effects of CO{sub 2}-fertilized vegetation on global climate and carbon dynamics, and the effect of climate sensitivity on carbon cycle feedback. We have also begun development of a next-generation climate/carbon modeling capability.
Date: December 14, 2004
Creator: Thompson, S.
Object Type: Report
System: The UNT Digital Library