Solution Verification Linked to Model Validation, Reliability, and Confidence (open access)

Solution Verification Linked to Model Validation, Reliability, and Confidence

The concepts of Verification and Validation (V&V) can be oversimplified in a succinct manner by saying that 'verification is doing things right' and 'validation is doing the right thing'. In the world of the Finite Element Method (FEM) and computational analysis, it is sometimes said that 'verification means solving the equations right' and 'validation means solving the right equations'. In other words, if one intends to give an answer to the equation '2+2=', then one must run the resulting code to assure that the answer '4' results. However, if the nature of the physics or engineering problem being addressed with this code is multiplicative rather than additive, then even though Verification may succeed (2+2=4 etc), Validation may fail because the equations coded are not those needed to address the real world (multiplicative) problem. We have previously provided a 4-step 'ABCD' quantitative implementation for a quantitative V&V process: (A) Plan the analyses and validation testing that may be needed along the way. Assure that the code[s] chosen have sufficient documentation of software quality and Code Verification (i.e., does 2+2=4?). Perform some calibration analyses and calibration based sensitivity studies (these are not validated sensitivities but are useful for planning purposes). Outline the …
Date: June 16, 2004
Creator: Logan, R W & Nitta, C K
Object Type: Report
System: The UNT Digital Library
Design and testing of a control strategy for a large naturallyventilated office building (open access)

Design and testing of a control strategy for a large naturallyventilated office building

The design for the new Federal Building for San Franciscoincludes an office tower that is to be naturally ventilated. Each flooris designed to be cross-ventilated, through upper windows that arecontrolled by the building management system (BMS). Users have controlover lower windows, which can be as much as 50 percent of the totalopenable area. There are significant differences in the performance andthe control of the windward and leeward sides of the building, andseparate monitoring and control strategies are determined for each side.The performance and control of the building has been designed and testedusing a modified version of EnergyPlus. Results from studies withEnergyPlus and CFD are used in designing the control strategy. EnergyPluswas extended to model a simplified version of the airflow patterndetermined using CFD. Wind-driven cross-ventilation produces a main jetthrough the upper openings of the building, across the ceiling from thewindward to the leeward side. Below this jet, the occupied regions aresubject to a recirculating air flow. Results show that temperatureswithin the building are predicted to be satisfactory, provided a suitablecontrol strategy is implemented uses night cooling in periods of hotweather. The control strategy has 10 window opening modes. EnergyPlus wasextended to simulate the effects of these modes, and to assess …
Date: March 16, 2004
Creator: Carrilho da Graca, Guilherme; Linden, Paul F. & Haves, Philip
Object Type: Article
System: The UNT Digital Library
Bridging the Gap between Quantum Mechanics and Large-Scale Atomistic Simulation (open access)

Bridging the Gap between Quantum Mechanics and Large-Scale Atomistic Simulation

The prospect of modeling across disparate length and time scales to achieve a predictive multiscale description of real materials properties has attracted widespread research interest in the last decade. To be sure, the challenges in such multiscale modeling are many, and in demanding cases, such as mechanical properties or dynamic phase transitions, multiple bridges extending from the atomic level all the way to the continuum level must be built. Although often overlooked in this process, one of the most fundamental and important problems in multiscale modeling is that of bridging the gap between first-principles quantum mechanics, from which true predictive power for real materials emanates, and the large-scale atomistic simulation of thousands or millions of atoms, which is usually essential to describe the complex atomic processes that link to higher length and time scales. For example, to model single-crystal plasticity at micron length scales via dislocation-dynamics simulations that evolve the detailed dislocation microstructure requires accurate large-scale atomistic information on the mobility and interaction of individual dislocations. Similarly, modeling the kinetics of structural phase transitions requires linking accurate large-scale atomistic information on nucleation processes with higher length and time scale growth processes.
Date: August 16, 2004
Creator: Moriarty, J. A.
Object Type: Book
System: The UNT Digital Library
In-situ Diffraction Studies of Shock Compressed Single-Crystal Iron (open access)

In-situ Diffraction Studies of Shock Compressed Single-Crystal Iron

The technique of in-situ wide angle diffraction has been used to study materials such as Si and Cu. We have extended our studies of shocked single crystal materials to include Fe (001) that is shock compressed by direct laser irradiation using the OMEGA and Janus lasers. A series of experiments was conducted in Fe at pressures above the Hugoniot Elastic Limit. Transient x-ray was used to record the response of multiple lattice planes simultaneously. This technique of wide-angle diffraction provides information on the lattice response both parallel and oblique to the shock propagation direction. In these experiments, compressions of up to 14% in the (002) planes were observed. Details on the experiments and analysis of the dynamic lattice compression will be presented.
Date: July 16, 2004
Creator: Kalantar, D H; Colvin, J D; Eggert, J; Lorenzana, H; Stolken, J; Hawreliak, J et al.
Object Type: Article
System: The UNT Digital Library
Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition (open access)

Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition

The use of fs lasers to directly write photonic structures inside a glass has great potential as a fabrication method for three-dimensional all-optical integrated components. The ability to use this technique with different glass compositions--specifically tailored for a specific photonics application--is critical to its successful exploitation. Consequently, it is important to understand how glass composition effects waveguide fabrication with fs laser pulses and how different glasses are structurally modified after exposure to fs laser pulses. We have used confocal laser spectroscopy to monitor the changes in glass structure that are associated with waveguide fabrication. Using a low power continuous wave (cw) Ar laser as excitation source we have measured both Raman and fluorescence spectra of the modified regions. Raman spectroscopy provides us with information on the network structure, whereas fluorescence measurements reveal the presence of optically active point defects in the glass. In this paper we review our work on fs-laser fabrication and characterization of photonic structures in glass and discuss the effect of glass composition on processing parameters and structural modification.
Date: June 16, 2004
Creator: Krol, D M; Chan, J W; Huser, T R; Risbud, S H & Hayden, J S
Object Type: Article
System: The UNT Digital Library
Status of The General Atomics Low Speed Urban Maglev Technology Development Program (open access)

Status of The General Atomics Low Speed Urban Maglev Technology Development Program

This paper presents the status of General Atomics Urban Maglev Program. The development provides an innovative approach for low speed transportation suitable for very challenging urban environments. Permanent magnets arranged in a 'Halbach' array configuration produce a relatively stiff magnetic suspension operating with an air gap of 25 mm. The project has progressed from design and prototype hardware testing, to the construction of a 120-meter full-scale test track, located in San Diego, California. Dynamic testing of the levitation, propulsion and guidance systems is being performed.
Date: June 16, 2004
Creator: Gurol, S; Baldi, R; Bever, D & Post, R
Object Type: Article
System: The UNT Digital Library
The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer (open access)

The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer

The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration 'library' for the Astro-E2 observatory.
Date: April 16, 2004
Creator: Porter, F S; Brown, G V; Boyce, K R; Kelley, R L; Kilbourne, C A; Beiersdorfer, P et al.
Object Type: Article
System: The UNT Digital Library
Massive Data Pre-Processing with a Cluster Based Approach (open access)

Massive Data Pre-Processing with a Cluster Based Approach

Data coming from complex simulation models reach easily dimensions much greater than available computational resources. Visualization of such data still represents the most intuitive and effective tool for scientific inspection of simulated phenomena. To ease this process several techniques have been adopted mainly concerning the use of hierarchical multi-resolution representations. In this paper we present the implementation of a hierarchical indexing schema for multiresolution data tailored to overwork the computational power of distributed environments.
Date: December 16, 2004
Creator: Borgo, R.; Cignoni, P.; Pascucci, V. & Scopigno, R.
Object Type: Article
System: The UNT Digital Library
Experimental and Numerical Investigation of the Role of Initial Condition of the Dynamics of Rayleigh-Taylor Mixing (open access)

Experimental and Numerical Investigation of the Role of Initial Condition of the Dynamics of Rayleigh-Taylor Mixing

Experiments and direct numerical simulations have been performed to examine the effects of initial conditions on the dynamics of a Rayleigh-Taylor mixing layer. Experiments were performed on a water channel facility to quantify the interfacial and velocity perturbations initially present at the two-fluid interface in a small Atwood number mixing layer. The measurements have been parameterized for implementation in numerical simulations of the experiment, and two- and three-dimensional direct numerical simulations (DNS) of the experiment have been performed. It is shown that simulations implemented with initial velocity perturbations are required to match experimentally-measured statistics. Data acquired from both the experiment and numerical simulations are used to elucidate the role of initial conditions on the evolution of integral-scale, turbulence, and mixing statistics. Early-time turbulence and mixing statistics will be shown to be strongly dependent upon the early-time transition of the initial perturbation from a weakly- to a strongly-nonlinear flow.
Date: August 16, 2004
Creator: Mueschke, N
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Ultrasonic Time-of-Flight Measurements on Binary U-6Nb Cubes (open access)

Ultrasonic Time-of-Flight Measurements on Binary U-6Nb Cubes

I performed contact ultrasonic time-of-flight measurements on three binary U-6 wt-% Nb alloy (U-6Nb) cubes. Using the time-of-flight measurement results, thickness, and density, the Acoustic Velocity, Poisson's Ratio, Shear Modulus, and Modulus of Elasticity are calculated. A detailed data is summarized in the spreadsheets 1-6. The calculated data compares the material properties of each cube before and after a heat treatment (HT). The time-of-flight measurements were performed using the pulse/echo signal overlap technique discussed in the Review of Ultrasonic Pulse/Echo Signal Overlap Technique section of this report. The measurements were made using both the longitudinal and shear ultrasonic modes and acquired in the X, Y, and Z axes of each cube, as represented in Figure 1. Thickness and density measurements on the three cubes were performed by the Manufacturing and Materials Engineering Division, Dimensional Inspection Group. The HT was performed on all three cubes in the Manufacturing and Materials Engineering Division, Heat Treat Shop. The process consisted of 200 C for 2 hours in a vacuum furnace, followed by an argon purge to 25 C.
Date: December 16, 2004
Creator: Souza, P. R.
Object Type: Report
System: The UNT Digital Library
Software Quality Assurance for Nuclear Safety Systems (open access)

Software Quality Assurance for Nuclear Safety Systems

The US Department of Energy has undertaken an initiative to improve the quality of software used to design and operate their nuclear facilities across the United States. One aspect of this initiative is to revise or create new directives and guides associated with quality practices for the safety software in its nuclear facilities. Safety software includes the safety structures, systems, and components software and firmware, support software and design and analysis software used to ensure the safety of the facility. DOE nuclear facilities are unique when compared to commercial nuclear or other industrial activities in terms of the types and quantities of hazards that must be controlled to protect workers, public and the environment. Because of these differences, DOE must develop an approach to software quality assurance that ensures appropriate risk mitigation by developing a framework of requirements that accomplishes the following goals: {sm_bullet} Ensures the software processes developed to address nuclear safety in design, operation, construction and maintenance of its facilities are safe {sm_bullet} Considers the larger system that uses the software and its impacts {sm_bullet} Ensures that the software failures do not create unsafe conditions Software designers for nuclear systems and processes must reduce risks in software applications …
Date: May 16, 2004
Creator: Sparkman, D R & Lagdon, R
Object Type: Article
System: The UNT Digital Library
K-Alpha Emission Spectra From Non-Equilibrium Ionizing Plasmas (open access)

K-Alpha Emission Spectra From Non-Equilibrium Ionizing Plasmas

K{alpha} X-ray emission spectra from highly charged Fe ions have been theoretically predicted using a detailed and systematic spectral model. Account has been taken of the fundamental atomic radiative-emission processes associated with inner-shell electron collisional excitation and ionization, as well as dielectronic recombination. Particular emphasis has been directed at extreme non-equilibrium or transient-ionization conditions, which can occur in astrophysical and tokamak plasmas. Good agreement has been found in comparisons with spectral observations on the EBIT-II electron beam ion trap at the Lawrence Livermore National Laboratory. We have identified spectral features that can serve as diagnostics of the electron density, the line-formation mechanism, and the charge-state distribution.
Date: December 16, 2004
Creator: Jacobs, V L; Decaux, V & Beiersdorfer, P
Object Type: Article
System: The UNT Digital Library
Parallel Computation of the Topology of Level Sets (open access)

Parallel Computation of the Topology of Level Sets

This paper introduces two efficient algorithms that compute the Contour Tree of a 3D scalar field F and its augmented version with the Betti numbers of each isosurface. The Contour Tree is a fundamental data structure in scientific visualization that is used to preprocess the domain mesh to allow optimal computation of isosurfaces with minimal overhead storage. The Contour Tree can also be used to build user interfaces reporting the complete topological characterization of a scalar field, as shown in Figure 1. Data exploration time is reduced since the user understands the evolution of level set components with changing isovalue. The Augmented Contour Tree provides even more accurate information segmenting the range space of the scalar field in portion of invariant topology. The exploration time for a single isosurface is also improved since its genus is known in advance. Our first new algorithm augments any given Contour Tree with the Betti numbers of all possible corresponding isocontours in linear time with the size of the tree. Moreover we show how to extend the scheme introduced in [3] with the Betti number computation without increasing its complexity. Thus, we improve on the time complexity from our previous approach [10] from O(m …
Date: December 16, 2004
Creator: Pascucci, V & Cole-McLaughlin, K
Object Type: Article
System: The UNT Digital Library
Integration Architecture Capability Case Model (open access)

Integration Architecture Capability Case Model

None
Date: April 16, 2004
Creator: Watts, R A
Object Type: Report
System: The UNT Digital Library
Singlet Free Energies of a Static Quark-Antiquark Pair. (open access)

Singlet Free Energies of a Static Quark-Antiquark Pair.

We study the singlet part of the free energy of a static quark anti-quark (Q{bar Q}) pair at finite temperature. The model is three flavor QCD with degenerate quark masses using N{sub {tau}} = 4 and 6 lattices with Asqtad staggered fermion action. We look at thermodynamics of the system around phase transition and study its scaling with lattice spacing and quark masses.
Date: June 16, 2004
Creator: Petrov, Konstantin
Object Type: Article
System: The UNT Digital Library
Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation (open access)

Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation

We systematically investigate the embedding of U(1)_X Froggatt-Nielsen models in (four-dimensional) local supersymmetry. We restrict ourselves to models with a single flavon field. We do not impose a discrete symmetry by hand, e.g., R-parity, baryon-parity or lepton-parity. Thus we determine the order of magnitude of the baryon- and/or lepton violating coupling constants through the Froggatt-Nielsen mechanism. We then scrutinize whether the predicted coupling constants are in accord with weak or GUT scale constraints. Many models turn out to be incompatible.
Date: April 16, 2004
Creator: Dreiner, Herbi K. & Thormeier, Marc
Object Type: Article
System: The UNT Digital Library
Warped Supersymmetric Unification with Non-Unified Superparticle Spectrum (open access)

Warped Supersymmetric Unification with Non-Unified Superparticle Spectrum

We present a new supersymmetric extension of the standard model. The model is constructed in warped space, with a unified bulk symmetry broken by boundary conditions on both the Planck and TeV branes. In the supersymmetric limit, the massless spectrum contains exotic colored particles along with the particle content of the minimal supersymmetric standard model (MSSM). Nevertheless, the model still reproduces the MSSM prediction for gauge coupling unification and does not suffer from a proton decay problem. The exotic states acquire masses from supersymmetry breaking, making the model completely viable, but thereis still the possibility that these states will be detected at the LHC. The lightest of these states is most likely A_5^XY, the fifth component of the gauge field associated with the broken unified symmetry. Because supersymmetry is broken on the SU(5)-violating TeV brane, the gaugino masses generated at the TeV scale are completely independent of one another. We explore some of the unusual features that the superparticle spectrum might have as a consequence.
Date: March 16, 2004
Creator: Nomura, Yasunori; Tucker-Smith, David & Tweedie, Brock
Object Type: Article
System: The UNT Digital Library
Matter Unification in Warped Supersymmetric SO(10) (open access)

Matter Unification in Warped Supersymmetric SO(10)

We construct models of warped unification with a bulk SO(10) gauge symmetry and boundary conditions that preserve the SU(4)_C x SU(2)_L x SU(2)_R Pati-Salam gauge group (422). In the dual 4D description, these models are 422 gauge theories in which the apparent unification of gauge couplings in the minimal supersymmetric standard model is explained as a consequence of strong coupling in the ultraviolet. The weakness of the gauge couplings at low energies is ensured in this 4D picture by asymptotically non-free contributions from the conformal sector, which are universal due to an approximate SO(10) global symmetry. The 422 gauge symmetry is broken to the standard model group by a simple set of Higgs fields. An advantage of this setup relative to SU(5) models of warped unification is that matter is automatically required to fill out representations of 422, providing an elegant understanding of the quantum numbers of the standard-model quarks and leptons. The models also naturally incorporate the see-saw mechanism for neutrino masses and bottom-tau unification. Finally, they predict a rich spectrum of exotic particles near the TeV scale, including states with different quantum numbers than those that appear in SU(5) models.
Date: March 16, 2004
Creator: Nomura, Yasunori & Tucker-Smith, David
Object Type: Article
System: The UNT Digital Library
Chemical Interactions in Multimetal/Zeolite Catalysts (open access)

Chemical Interactions in Multimetal/Zeolite Catalysts

This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that …
Date: April 16, 2004
Creator: Sachtler, Wolfgang M. H.
Object Type: Report
System: The UNT Digital Library
Modeling the Transport and Chemical Evolution of Onshore and Offshore Emissions and their Impact on Local and Regional Air Quality Using a Variable-Grid-Resolution Air Quality Model (open access)

Modeling the Transport and Chemical Evolution of Onshore and Offshore Emissions and their Impact on Local and Regional Air Quality Using a Variable-Grid-Resolution Air Quality Model

This semiannual report summarizes the research performed from 17 April through 16 October 2004. Major portions of the research in several of the project's current eight tasks have been completed, and the results obtained are briefly presented. We have successfully developed the meteorological inputs using the best possible modeling configurations, resulting in improved representation of atmospheric processes. Ingestion of satellite-derived sea surface temperatures in conjunction with the use of our new surface data assimilation technique have resulted in largely improved meteorological inputs to drive the MAQSIP-VGR. The development of the variable-grid-resolution emissions model, SMOKE-VGR, is also largely complete. We expect to develop the final configuration of the SMOKE-VGR during the upcoming reporting period. We are in the process of acquiring the newly released emissions database and offshore emissions data sets to update our archives. The development of the MAQSIP-VGR has been completed and a test run was performed to ensure the functionality of this air quality model. During the upcoming reporting period, we expect to perform the first MAQSIP-VGR simulations over the Houston-Galveston region to study the roles of the meteorology, offshore emissions, and chemistry-transport interactions that determine the temporal and spatial evolution of ozone and its precursors.
Date: October 16, 2004
Creator: Alapaty, Kiran
Object Type: Report
System: The UNT Digital Library
Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source (open access)

Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source

The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way for the study of fast structural dynamics and the role they play in phase transitions, chemical reactions and the emergence of exotic properties in materials with strongly interacting degrees of freedom. The ultrashort pulse x-ray source developed at the Advanced Light Source at the Lawrence Berkeley Laboratory is based on electron slicing in storage rings, and generates {approx}100 femtosecond pulses of synchrotron radiation spanning wavelengths from the far-infrared to the hard x-ray region of the electromagnetic spectrum. The tunability of the source allows for the adaptation of a broad range of static x-ray spectroscopies to useful pump-probe measurements. Initial experiments are attempted on transition metal complexes that exhibit relatively large structural changes upon photo-excitation and which have excited-state evolution determined by strongly interacting structural, electronic and magnetic degrees …
Date: April 16, 2004
Creator: Chong, Henry Herng Wei
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors (open access)

Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

Sorption of cesium and strontium on kaolinite powders was investigated as a means to minimize the emissions of these metals during certain high temperature processes currently being developed to isolate and dispose of radiological and mixed wastes. In this work, non-radioactive aqueous cesium acetate or strontium acetate was atomized down the center of a natural gas flame supported on a variable-swirl burner in a refractory-lined laboratory-scale combustion facility. Kaolinite powder was injected at a post-flame location in the combustor. Cesium readily vaporizes in the high temperature regions of the combustor, but was reactively scavenged onto dispersed kaolinite. Global sorption mechanisms of cesium vapor on kaolinite were quantified, and are related to those available in the literature for sodium and lead. Both metal adsorption and substrate deactivation steps are important, and so there is an optimum temperature, between 1400 and 1500 K, at which maximum sorption occurs. The presence of chlorine inhibits cesium sorption. In contrast to cesium, and in the absence of chlorine, strontium was only partially vaporized and was, therefore, only partially scavengeable. The strontium data did not allow quantification of global kinetic mechanisms of interaction, although equilibrium arguments provided insight into the effects of chlorine on strontium sorption. …
Date: December 16, 2004
Creator: Linak, William
Object Type: Report
System: The UNT Digital Library
Drift Degradation Analysis (open access)

Drift Degradation Analysis

Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping …
Date: September 16, 2004
Creator: Kicker, D.
Object Type: Report
System: The UNT Digital Library
Extraction of Poloidal Velocity from Charge Exchange Recombination Spectroscopy Measurements (open access)

Extraction of Poloidal Velocity from Charge Exchange Recombination Spectroscopy Measurements

A novel approach has been implemented on DIII-D to allow the correct determination of the plasma poloidal velocity from charge exchange spectroscopy measurements. Unlike usual techniques, the need for detailed atomic physics calculations to properly interpret the results is alleviated. Instead, the needed atomic physics corrections are self-consistently determined directly from the measurements, by making use of specially chosen viewing chords. Modeling results are presented that were used to determine a set of views capable of measuring the correction terms. We present the analysis of a quiescent H-mode discharge, illustrating that significant modifications to the velocity profiles are required in these high ion temperature conditions. We also present preliminary measurements providing the first direct comparison of the standard cross-section correction to the atomic physics calculations.
Date: July 16, 2004
Creator: Solomon, W. M.; Burrell, K. H.; Gohil, P.; Groebner, R. J. & Baylor, L. R.
Object Type: Report
System: The UNT Digital Library