Recent Developments in High-Harmonic Fast Wave Physics in NSTX (open access)

Recent Developments in High-Harmonic Fast Wave Physics in NSTX

Understanding the interaction between ion cyclotron range of frequency (ICRF) fast waves and the fast-ions created by neutral beam injection (NBI) is critical for future devices such as ITER, which rely on a combination ICRF and NBI. Experiments in NSTX which use 30 MHz High-Harmonic Fast-Wave (HHFW) ICRF and NBI heating show a competition between electron heating via Landau damping and transit-time magnetic pumping, and radio-frequency wave acceleration of NBI generated fast ions. Understanding and mitigating some of the power loss mechanisms outside the last closed flux surface (LCFS) has resulted in improved HHFW heating inside the LCFS. Nevertheless a significant fraction of the HHFW power is diverted away from the enclosed plasma. Part of this power is observed locally on the divertor. Experimental observations point toward the radio-frequency (RF) excitation of surface waves, which disperse wave power outside the LCFS, as a leading loss mechanism. Lithium coatings lower the density at the antenna, thereby moving the critical density for perpendicular fast-wave propagation away from the antenna and surrounding material surfaces. Visible and infrared imaging reveal flows of RF power along open field lines into the divertor region. In L-mode -- low average NBI power -- conditions, the fast-ion D-alpha …
Date: October 6, 2010
Creator: LeBlanc, B. P.; Bell, R. E.; Bonoli, P.; Harvey, R.; Heidbrink, W. W.; Hosea, J. C. et al.
Object Type: Article
System: The UNT Digital Library
Comparing GPU Implementations of Bilateral and Anisotropic Diffusion Filters for 3D Biomedical Datasets (open access)

Comparing GPU Implementations of Bilateral and Anisotropic Diffusion Filters for 3D Biomedical Datasets

We compare the performance of hand-tuned CUDA implementations of bilateral and anisotropic diffusion filters for denoising 3D MRI datasets. Our tests sweep comparable parameters for the two filters and measure total runtime, memory bandwidth, computational throughput, and mean squared errors relative to a noiseless reference dataset.
Date: May 6, 2010
Creator: Howison, Mark
Object Type: Report
System: The UNT Digital Library
Development of Sensors and Sensing Technology for Hydrogen Fuel Cell Vehicle Applications (open access)

Development of Sensors and Sensing Technology for Hydrogen Fuel Cell Vehicle Applications

One related area of hydrogen fuel cell vehicle (FCV) development that cannot be overlooked is the anticipated requirement for new sensors for both the monitoring and control of the fuel cell's systems and for those devices that will be required for safety. Present day automobiles have dozens of sensors on-board including those for IC engine management/control, sensors for state-of-health monitoring/control of emissions systems, sensors for control of active safety systems, sensors for triggering passive safety systems, and sensors for more mundane tasks such as fluids level monitoring to name the more obvious. The number of sensors continues to grow every few years as a result of safety mandates but also in response to consumer demands for new conveniences and safety features. Some of these devices (e.g. yaw sensors for dynamic stability control systems or tire presure warning RF-based devices) may be used on fuel cell vehicles without any modification. However the use of hydrogen as a fuel will dictate the development of completely new technologies for such requirements as the detection of hydrogen leaks, sensors and systems to continuously monitor hydrogen fuel purity and protect the fuel cell stack from poisoning, and for the important, yet often taken for granted, …
Date: January 6, 2010
Creator: Brosha, E. L.; Sekhar, P. K.; Mukundan, R.; Williamson, T.; Garzon, F. H.; Woo, L. Y. et al.
Object Type: Article
System: The UNT Digital Library
Fish Tales (open access)

Fish Tales

This talk is about fishing and the friendships that have resulted in its pursuit. It is also about theoretical physics, and the relationship of imagination and fantasy to the establishment of ideas about nature. Fishermen, like theoretical physicists, are well known for their inventive imaginations. Perhaps neither are as clever as sailors, who conceived of the mermaid. If one doubts the power of this fantasy, one should remember the ghosts of the many sailors who drowned pursuing these young nymphs. An extraordinary painting by J. Waterhouse is shown as Fig. 1. The enchantment of a mermaid must reflect an extraordinary excess of imagination on the part of the sailor, perhaps together with an impractical turn of mind. A consummated relationship with a mermaid is after all, by its very nature a fantasy incapable of realization. To a theoretical physicist, she is symbolic of many ideas we develop. There are many truths known to fisherman in which one might also find parallels to the goals of scientists: (1) A fish is the only animal that keeps growing after its death; (2) Nothing makes a fish bigger than almost being caught; (3) ''...of all the liars among mankind, the fisherman is the …
Date: July 6, 2010
Creator: McLerran, L.
Object Type: Article
System: The UNT Digital Library
Nondestructive depth-resolved spectroscopic investigation of the heavily intermixed In2S3/Cu(In,Ga)Se2 interface (open access)

Nondestructive depth-resolved spectroscopic investigation of the heavily intermixed In2S3/Cu(In,Ga)Se2 interface

The chemical structure of the interface between a nominal In2S3 buffer and a Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorber was investigated by soft x-ray photoelectron and emission spectroscopy. We find a heavily intermixed, complex interface structure, in which Cu diffuses into (and Na through) the buffer layer, while the CIGSe absorber surface/interface region is partially sulfurized. Based on our spectroscopic analysis, a comprehensive picture of the chemical interface structure is proposed.
Date: April 6, 2010
Creator: Bar, Marcus; Barreau, N.; Couzinie-Devy, F.; Pookpanratana, S.; Klaer, J.; Blum, M. et al.
Object Type: Article
System: The UNT Digital Library
Water Induced Surface Reconstruction of the Oxygen (2x1) covered Ru(0001) (open access)

Water Induced Surface Reconstruction of the Oxygen (2x1) covered Ru(0001)

Low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) were used to study the adsorption of water on a Ru(0001) surface covered with half monolayer of oxygen. The oxygen atoms occupy hcp sites in an ordered structure with (2x1) periodicity. DFT predicts that water is weakly bound to the unmodified surface, 86 meV compared to the ~;;200 meV water-water H-bond. Instead, we found that water adsorption causes a shift of half of the oxygen atoms from hcp sites to fcc sites, creating a honeycomb structure where water molecules bind strongly to the exposed Ru atoms. The energy cost of reconstructing the oxygen overlayer, around 230 meV per displaced oxygen atom, is more than compensated by the larger adsorption energy of water on the newly exposed Ru atoms. Water forms hydrogen bonds with the fcc O atoms in a (4x2) superstructure due to alternating orientations of the molecules. Heating to 185 K results in the complete desorption of the water layer, leaving behind the oxygen honeycomb structure, which is metastable relative to the original (2x1). This stable structure is not recovered until after heating to temperatures close to 260K.
Date: August 6, 2010
Creator: Maier, Sabine; Cabrera-Sanfelix, Pepa; Stass, Ingeborg; Sanchez-Portal, Daniel; Arnau, Andres & Salmeron, Miquel
Object Type: Article
System: The UNT Digital Library
The Stability and Electrical Properties of High Temperature Proton Conductors (open access)

The Stability and Electrical Properties of High Temperature Proton Conductors

The morphological and electrical properties of Ba{sub 1-x}Sr{sub x}Ce{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} with x varying from 0 to 1 prepared by a modified Pechini method were investigated as potential high temperature proton conductors. Dense microstructures were achieved for all the samples upon sintering at 1500 C for 5 h. The phase structure analysis indicated that perovskite phase was formed for 0 {le} x {le} 0.2, while for x larger than 0.5, impurity phases of Sr{sub 2}CeO{sub 4} and Y{sub 2}O{sub 3} appeared. The tolerance to H{sub 2}O for the samples improved with the increase in Sr content when exposed to boiling water, while the electrical conductivity decreased from x = 0 to 1. However, the resistance to CO{sub 2} attack at elevated temperatures was not improved within the whole x range studied.
Date: July 6, 2010
Creator: Brinkman, K.
Object Type: Article
System: The UNT Digital Library
Comment on “Precise half-life values for two-neutrino double beta decay” (open access)

Comment on “Precise half-life values for two-neutrino double beta decay”

The results by A.S. Barabash [Phys. Rev. C 81, 035501 (2010)] are shown to be incomplete.
Date: May 6, 2010
Creator: Pritychenko, B.
Object Type: Report
System: The UNT Digital Library
Aircraft Cabin Environmental Quality Sensors (open access)

Aircraft Cabin Environmental Quality Sensors

The Indoor Environment Department at Lawrence Berkeley National Laboratory (LBNL) teamed with seven universities to participate in a Federal Aviation Administration (FAA) Center of Excellence (COE) for research on environmental quality in aircraft. This report describes research performed at LBNL on selecting and evaluating sensors for monitoring environmental quality in aircraft cabins, as part of Project 7 of the FAA's COE for Airliner Cabin Environmental Research (ACER)1 effort. This part of Project 7 links to the ozone, pesticide, and incident projects for data collection and monitoring and is a component of a broader research effort on sensors by ACER. Results from UCB and LBNL's concurrent research on ozone (ACER Project 1) are found in Weschler et al., 2007; Bhangar et al. 2008; Coleman et al., 2008 and Strom-Tejsen et al., 2008. LBNL's research on pesticides (ACER Project 2) in airliner cabins is described in Maddalena and McKone (2008). This report focused on the sensors needed for normal contaminants and conditions in aircraft. The results are intended to complement and coordinate with results from other ACER members who concentrated primarily on (a) sensors for chemical and biological pollutants that might be released intentionally in aircraft; (b) integration of sensor systems; and …
Date: May 6, 2010
Creator: Gundel, Lara; Kirchstetter, Thomas; Spears, Michael & Sullivan, Douglas
Object Type: Report
System: The UNT Digital Library
Reaching Grid Parity Using BP Solar Crystalline Silicon Technology: A Systems Class Application (open access)

Reaching Grid Parity Using BP Solar Crystalline Silicon Technology: A Systems Class Application

The primary target market for this program was the residential and commercial PV markets, drawing on BP Solar's premium product and service offerings, brand and marketing strength, and unique routes to market. These two markets were chosen because: (1) in 2005 they represented more than 50% of the overall US PV market; (2) they are the two markets that will likely meet grid parity first; and (3) they are the two market segments in which product development can lead to the added value necessary to generate market growth before reaching grid parity. Federal investment in this program resulted in substantial progress toward the DOE TPP target, providing significant advancements in the following areas: (1) Lower component costs particularly the modules and inverters. (2) Increased availability and lower cost of silicon feedstock. (3) Product specifically developed for residential and commercial applications. (4) Reducing the cost of installation through optimization of the products. (5) Increased value of electricity in mid-term to drive volume increases, via the green grid technology. (6) Large scale manufacture of PV products in the US, generating increased US employment in manufacturing and installation. To achieve these goals BP Solar assembled a team that included suppliers of critical materials, …
Date: December 6, 2010
Creator: Cunningham, Daniel W.; Wohlgemuth, John; Carlson, David E.; Clark, Roger F.; Gleaton, Mark; Posbic, John P. et al.
Object Type: Report
System: The UNT Digital Library
Hydrogen and Water: An Engineering, Economic and Environmental Analysis (open access)

Hydrogen and Water: An Engineering, Economic and Environmental Analysis

The multi-year program plan for the Department of Energy's Hydrogen and Fuel Cells Technology Program (USDOE, 2007a) calls for the development of system models to determine economic, environmental and cross-cutting impacts of the transition to a hydrogen economy. One component of the hydrogen production and delivery chain is water; water's use and disposal can incur costs and environmental consequences for almost any industrial product. It has become increasingly clear that due to factors such as competing water demands and climate change, the potential for a water-constrained world is real. Thus, any future hydrogen economy will need to be constructed so that any associated water impacts are minimized. This, in turn, requires the analysis and comparison of specific hydrogen production schemes in terms of their water use. Broadly speaking, two types of water are used in hydrogen production: process water and cooling water. In the production plant, process water is used as a direct input for the conversion processes (e.g. steam for Steam Methane Reforming {l_brace}SMR{r_brace}, water for electrolysis). Cooling water, by distinction, is used indirectly to cool related fluids or equipment, and is an important factor in making plant processes efficient and reliable. Hydrogen production further relies on water used …
Date: January 6, 2010
Creator: Simon, A. J.; Daily, W. & White, R. G.
Object Type: Report
System: The UNT Digital Library
FIELD TEST INSTRUCTION 100-NR-2 OPERABLE UNIT DESIGN OPTIMIZATION STUDY FOR SEQUESTRATION OF SR-90 SATURATED ZONE APATITE PERMEABLE REACTIVE BARRIER EXTENSION (open access)

FIELD TEST INSTRUCTION 100-NR-2 OPERABLE UNIT DESIGN OPTIMIZATION STUDY FOR SEQUESTRATION OF SR-90 SATURATED ZONE APATITE PERMEABLE REACTIVE BARRIER EXTENSION

The objective of this field test instruction is to provide technical guidance for aqueous injection emplacement of an extension apatite permeable reactive barrier (PRE) for the sequestration of strontium-90 (Sr-90) using a high concentration amendment formulation. These field activities will be conducted according to the guidelines established in DOE/RL-2010-29, 100-NR-2 Design Optimization Study, hereafter referred to as the DOS. The DOS supports the Federal Facility Agreement Consent Order (EPA et al., 1989), Milestone M-16-06-01, and 'Complete Construction of a Permeable Reactive Barrier at 100-N.' Injections of apatite precursor chemicals will occur at an equal distance intervals on each end of the existing PRE to extend the PRB from the existing 91 m (300 ft) to at least 274 m (900 ft). Field testing at the 100-N Area Apatite Treatability Test Site, as depicted on Figure 1, shows that the barrier is categorized by two general hydrologic conceptual models based on overall well capacity and contrast between the Hanford and Ringold hydraulic conductivities. The upstream portion of the original barrier, shown on Figure 1, is characterized by relatively low overall well specific capacity. This is estimated from well development data and a lower contrast in hydraulic conductivity between the Hanford formation …
Date: October 6, 2010
Creator: NA, BOWLES
Object Type: Report
System: The UNT Digital Library
Image Processing and Control of a Programmable Spatial Light Modulator for Optic Damage Protection (open access)

Image Processing and Control of a Programmable Spatial Light Modulator for Optic Damage Protection

The heart of the National Ignition Facility is a megajoule-class laser system consisting of 192 beams used to drive inertial confinement fusion reactions. A recently installed system of programmable, liquid-crystal-based spatial light modulators adds the capability of arbitrarily shaping the spatial beam profiles in order to enhance operational flexibility. Its primary intended use is for introducing 'blocker' obscurations shadowing isolated flaws on downstream optical elements that would otherwise be damaged by high fluence laser illumination. Because an improperly shaped blocker pattern can lead to equipment damage, both the position and shape of the obscurations must be carefully verified prior to high-fluence operations. An automatic alignment algorithm is used to perform detection and estimation of the imposed blocker centroid positions compared to their intended locations. Furthermore, in order to minimize the spatially-varying nonlinear response of the device, a calibration of the local magnification is performed at multiple sub-image locations. In this paper, we describe the control and associated image processing of this device that helps to enhance the safety and longevity of the overall system.
Date: December 6, 2010
Creator: Awwal, A.; Leach, R.; Brunton, G.; Tse, E.; Matone, J. & Heebner, J.
Object Type: Article
System: The UNT Digital Library
Illuminating the Pecking Order in Off-Grid Lighting: A Demonstration of LED Lighting for Saving Energy in the Poultry Sector (open access)

Illuminating the Pecking Order in Off-Grid Lighting: A Demonstration of LED Lighting for Saving Energy in the Poultry Sector

The Lumina Project and Lighting Africa conducted a full-scale field test involving a switch from kerosene to solar-LED lighting for commercial broiler chicken production at an off-grid farm in Kenya. The test achieved lower operating costs, produced substantially more light, improved the working environment, and had no adverse effect on yields. A strategy using conventional solar-fluorescent lighting also achieved comparable yields, but entailed a six-fold higher capital cost and significantly higher recurring battery replacement costs. Thanks to higher energy and optical efficiencies, the LED system provided approximately twice the illumination to the chicken-production area and yet drew less than half the power.At the study farm, 3000 chickens were grown in each of three identical houses under kerosene, fluorescent, and LED lighting configurations. Under baseline conditions, a yearly expenditure of 1,200 USD is required to illuminate the three houses with kerosene. The LED system eliminates this fuel use and expense with a corresponding simple payback time of 1.5 years, while the solar-fluorescent system has a payback time of 9.3 years. The corresponding reduction in fuel expenditure in both cases represents a 15percent increase in after-tax net income (revenues minus expenses) across the entire business operation. The differential cost-effectiveness between the LED …
Date: November 6, 2010
Creator: Tracy, Jennifer & Mills, Evan
Object Type: Article
System: The UNT Digital Library
Satellite Collision Modeling with Physics-Based Hydrocodes: Debris Generation Predictions of the Iridium-Cosmos Collision Event and Other Impact Events (open access)

Satellite Collision Modeling with Physics-Based Hydrocodes: Debris Generation Predictions of the Iridium-Cosmos Collision Event and Other Impact Events

Satellite collision debris poses risks to existing space assets and future space missions. Predictive models of debris generated from these hypervelocity collisions are critical for developing accurate space situational awareness tools and effective mitigation strategies. Hypervelocity collisions involve complex phenomenon that spans several time- and length-scales. We have developed a satellite collision debris modeling approach consisting of a Lagrangian hydrocode enriched with smooth particle hydrodynamics (SPH), advanced material failure models, detailed satellite mesh models, and massively parallel computers. These computational studies enable us to investigate the influence of satellite center-of-mass (CM) overlap and orientation, relative velocity, and material composition on the size, velocity, and material type distributions of collision debris. We have applied our debris modeling capability to the recent Iridium 33-Cosmos 2251 collision event. While the relative velocity was well understood in this event, the degree of satellite CM overlap and orientation was ill-defined. In our simulations, we varied the collision CM overlap and orientation of the satellites from nearly maximum overlap to partial overlap on the outermost extents of the satellites (i.e, solar panels and gravity boom). As expected, we found that with increased satellite overlap, the overall debris cloud mass and momentum (transfer) increases, the average debris …
Date: September 6, 2010
Creator: Springer, H. K.; Miller, W. O.; Levatin, J. L.; Pertica, A. J. & Olivier, S. S.
Object Type: Article
System: The UNT Digital Library
Erratum: Time-step Considerations in Particle Simulation Algorithms for Coulomb Collisions in Plasmas [B.I. Cohen, A. M. Dimits, A. Friedman, and R. E. Caflisch, IEEE Trans. Plasma Sci. 38, 2394 (2010)] (open access)

Erratum: Time-step Considerations in Particle Simulation Algorithms for Coulomb Collisions in Plasmas [B.I. Cohen, A. M. Dimits, A. Friedman, and R. E. Caflisch, IEEE Trans. Plasma Sci. 38, 2394 (2010)]

None
Date: October 6, 2010
Creator: Cohen, B. I.; Dimits, A. M.; Friedman, A. & Caflisch, R.
Object Type: Article
System: The UNT Digital Library
A Case for the Use of 3-D Attenuation Models in Ground Motion and Seismic Hazard Assessment (open access)

A Case for the Use of 3-D Attenuation Models in Ground Motion and Seismic Hazard Assessment

None
Date: December 6, 2010
Creator: Pasyanos, M E
Object Type: Article
System: The UNT Digital Library
Detection of Hohlraum Target Position for Laser Fusion Experiments (open access)

Detection of Hohlraum Target Position for Laser Fusion Experiments

None
Date: July 6, 2010
Creator: Awwal, A. A.
Object Type: Article
System: The UNT Digital Library
Performance Analysis: Control of Hazardous Energy (open access)

Performance Analysis: Control of Hazardous Energy

None
Date: October 6, 2010
Creator: De Grange, C E; Freeman, J W & Kerr, C E
Object Type: Report
System: The UNT Digital Library
The dynamical core, physical parameterizations, and basic simulation characteristics of the atmospheric component of the GFDL global coupled model CM3 (open access)

The dynamical core, physical parameterizations, and basic simulation characteristics of the atmospheric component of the GFDL global coupled model CM3

None
Date: July 6, 2010
Creator: Donner, L. J.; Wyman, B. L.; Hemler, R. S.; Horowitz, L. W.; Ming, Y.; Zhao, M. et al.
Object Type: Article
System: The UNT Digital Library
EEMP Summary for NIF shot: N101004-002-999 (open access)

EEMP Summary for NIF shot: N101004-002-999

None
Date: October 6, 2010
Creator: Kimbrough, J
Object Type: Report
System: The UNT Digital Library
Compact fission counter for DANCE (open access)

Compact fission counter for DANCE

The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to …
Date: November 6, 2010
Creator: Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R.; Gostic, J.; Carter, D. et al.
Object Type: Report
System: The UNT Digital Library