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Analysis of Bulk DKDP Damage Distribution, Obscuration and Pulse Length Dependence (open access)

Analysis of Bulk DKDP Damage Distribution, Obscuration and Pulse Length Dependence

Recent LLNL experiments reported elsewhere at this conference explored the pulselength dependence of 351 nm bulk damage incidence in DKDP. The results found are consistent, in part, with a model in which a distribution of small bulk initiators is assumed to exist in the crystal and the damage threshold is determined by reaching a critical temperature. The observed pulse length dependence can be explained as being set by the most probable defect capable of causing damage at a given pulselength. Analysis of obscuration in side illuminated images of the damaged region yields estimates of the damage site distributions that are in reasonable agreement with the distributions experimentally directly estimated.
Date: December 15, 2000
Creator: Feit, M D; Rubenchik, A M & Runkel, M
System: The UNT Digital Library
Attomole quantitation of protein separations with accelerator mass spectrometry (open access)

Attomole quantitation of protein separations with accelerator mass spectrometry

Quantification of specific proteins depends on separation by chromatography or electrophoresis followed by chemical detection schemes such as staining and fluorophore adhesion. Chemical exchange of short-lived isotopes, particularly sulfur, is also prevalent despite the inconveniences of counting radioactivity. Physical methods based on isotopic and elemental analyses offer highly sensitive protein quantitation that has linear response over wide dynamic ranges and is independent of protein conformation. Accelerator mass spectrometry quantifies long-lived isotopes such as 14C to sub-attomole sensitivity. We quantified protein interactions with small molecules such as toxins, vitamins, and natural biochemicals at precisions of 1-5% . Micro-proton-induced-xray-emission quantifies elemental abundances in separated metalloprotein samples to nanogram amounts and is capable of quantifying phosphorylated loci in gels. Accelerator-based quantitation is a possible tool for quantifying the genome translation into proteome.
Date: December 15, 2000
Creator: Vogel, J. S.; Grant, P. G.; Buccholz, B. A.; Dingley, K. & Turteltaub, K. W.
System: The UNT Digital Library
BioSig: A bioinformatic system for studying the mechanism of intra-cell signaling (open access)

BioSig: A bioinformatic system for studying the mechanism of intra-cell signaling

Mapping inter-cell signaling pathways requires an integrated view of experimental and informatic protocols. BioSig provides the foundation of cataloging inter-cell responses as a function of particular conditioning, treatment, staining, etc. for either in vivo or in vitro experiments. This paper outlines the system architecture, a functional data model for representing experimental protocols, algorithms for image analysis, and the required statistical analysis. The architecture provides remote shared operation of an inverted optical microscope, and couples instrument operation with images acquisition and annotation. The information is stored in an object-oriented database. The algorithms extract structural information such as morphology and organization, and map it to functional information such as inter-cellular responses. An example of usage of this system is included.
Date: December 15, 2000
Creator: Parvin, B.; Cong, G.; Fontenay, G.; Taylor, J.; Henshall, R. & Barcellos-Hoff, M.H.
System: The UNT Digital Library
Computer Modeling of a Fusion Plasma (open access)

Computer Modeling of a Fusion Plasma

Progress in the study of plasma physics and controlled fusion has been profoundly influenced by dramatic increases in computing capability. Computational plasma physics has become an equal partner with experiment and traditional theory. This presentation illustrates some of the progress in computer modeling of plasma physics and controlled fusion.
Date: December 15, 2000
Creator: Cohen, B I
System: The UNT Digital Library
An Inertial-Fusion Z-Pinch Power Plant Concept (open access)

An Inertial-Fusion Z-Pinch Power Plant Concept

With the promising new results of fast z-pinch technology developed at Sandia National Laboratories, we are investigating using z-pinch driven high-yield Inertial Confinement Fusion (ICF) as a fusion power plant energy source. These investigations have led to a novel fusion system concept based on an attempt to separate many of the difficult fusion engineering issues and a strict reliance on existing technology, or a reasonable extrapolation of existing technology, wherever possible. In this paper, we describe the main components of such a system with a focus on the fusion chamber dynamics. The concept works with all of the electrically-coupled ICF proposed fusion designs. It is proposed that a z-pinch driven ICF power system can be feasibly operated at high yields (1 to 30 GJ) with a relatively low pulse rate (0.01-0.1 Hz). To deliver the required current from the rep-rated pulse power driver to the z-pinch diode, a Recyclable Transmission Line (RTL) and the integrated target hardware are fabricated, vacuum pumped, and aligned prior to loading for each power pulse. In this z-pinch driven system, no laser or ion beams propagate in the chamber such that the portion of the chamber outside the RTL does not need to be under …
Date: December 15, 2000
Creator: Derzon, Mark S.; Rochau, Gary A.; DeGroot, J.; Olson, Craig L.; Peterson, P.; Peterson, R. R. et al.
System: The UNT Digital Library
A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames (open access)

A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames

The oxidation of dimethyl ether (DME) is studied in low-pressure flames using new molecular beam mass spectrometer and laser diagnostics. Two 30.0-Torr, premixed DME/oxygen/argon flames are investigated with stoichiometries of 0.98 and 1.20. The height above burner profiles of nine stable species and two radicals are measured. These results are compared to the detailed chemical reaction mechanism of Curran and coworkers. Generally good agreement is found between the model and data. The largest discrepancies are found for the methyl radical profiles where the model predicts qualitatively different trends in the methyl concentration with stoichiometry than observed in the experiment.
Date: December 15, 2000
Creator: McIlroy, Andrew; Hain, Toby D.; Michelsen, Hope A. & Cool, Terrill A.
System: The UNT Digital Library
Pair creation and plasma oscillations. (open access)

Pair creation and plasma oscillations.

We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background fields and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses.
Date: December 15, 2000
Creator: Prozorkevich, A. V.; Vinnik, D. V.; Schmidt, S. M.; Hecht, M. B. & Roberts, C. D.
System: The UNT Digital Library
Structure of charged polymer chains in confined geometry. (open access)

Structure of charged polymer chains in confined geometry.

The intra- and interchain structure of sodium poly(styrenesulphonate) when free and when confined in contrast matched porous Vycor has been investigated by SANS. When confined, a peak is observed whose intensity increases with molecular weight and the 1/q scattering region is extended compared to the bulk. We infer that the chains are sufficiently extended, under the influence of confinement, to highlight the large scale disordered structure of Vycor. The asymptotic behavior of the observed interchain structure factor is = 1/q{sup 2} and = 1/q for free and confined chains respectively.
Date: December 15, 2000
Creator: Gilbert, E. P.; Auvray, L. & Lal, J.
System: The UNT Digital Library
Accurate Time-Linked Data Acqusition System Field Deploymemt and Operational Experience (open access)

Accurate Time-Linked Data Acqusition System Field Deploymemt and Operational Experience

None
Date: November 15, 2000
Creator: BERG,DALE E. & ZAYAS,JOSE R.
System: The UNT Digital Library
Application of TIVA in Design Debug (open access)

Application of TIVA in Design Debug

None
Date: November 15, 2000
Creator: Kolachina, Siva; Taylor, Bill; Wills, Kendall Scott & Cole, Edward I., Jr.
System: The UNT Digital Library
Carolina Geological Society 2000 Field Trip Guidebook (open access)

Carolina Geological Society 2000 Field Trip Guidebook

This guidebook will be distributed to 200 geologists for the Carolina Geological Society Meeting and the onsite field trip in November.
Date: November 15, 2000
Creator: Wyatt, D.E.
System: The UNT Digital Library
Carolina Geological Society 2000 Field Trip Guidebook - Geology: Improving Environmental Cleanup of the A/M Area, Savannah River Site (open access)

Carolina Geological Society 2000 Field Trip Guidebook - Geology: Improving Environmental Cleanup of the A/M Area, Savannah River Site

This guidebook will be distributed to 200 geologists for the Carolina Geological Society Meeting and the onsite field trip in November.
Date: November 15, 2000
Creator: Harris, M.K.
System: The UNT Digital Library
The Combined Effect of EPM and TAE Modes on Energetic Ion Confinement and Sawtooth Stabilization (open access)

The Combined Effect of EPM and TAE Modes on Energetic Ion Confinement and Sawtooth Stabilization

It is shown in this paper for the first time, that the chirping Alfven instabilities observed mostly during ion cyclotron range of frequency (ICRF) heating have been positively identified as Energetic Particle Modes (EPM). This has been possible because of the detailed measurement of the q-profile with the MSE (motional Stark effect) diagnostic in DIII-D. The EPMs are shown to be the leading cause of the monster sawtooth crash. It is also shown that TAEs are excited either directly or indirectly by the EPMs and they cause fast ion losses. A scenario for the stabilization and the crash of the monster sawtooth and for the degradation of the ICRF heating efficiency at high power is presented.
Date: November 15, 2000
Creator: Bernabei, S.; Budny, R.; Fredrickson, E. D.; Gorelenkov, N. N.; Hosea, J. C.; Phillips, C. K. et al.
System: The UNT Digital Library
Emerging Technologies and MOUT (open access)

Emerging Technologies and MOUT

Operating in a potentially hostile city is every soldier's nightmare. The staggering complexity of the urban environment means that deadly threats--or non-combatants-may lurk behind every corner, doorway, or window. Urban operations present an almost unparalleled challenge to the modern professional military. The complexity of urban operations is further amplified by the diversity of missions that the military will be called upon to conduct in urban terrain. Peace-making and peace-keeping missions, urban raids to seize airports or WMD sites or to rescue hostages, and extended urban combat operations all present different sorts of challenges for planners and troops on the ground. Technology almost never serves as a magic bullet, and past predictions of technological miracles pile high on the ash heap of history. At the same time, it is a vital element of planning in the modern age to consider and, if possible, take advantage of emerging technologies. We believe that technologies can assist military operations in urbanized terrain (MOUT) in three primary areas, which are discussed.
Date: November 15, 2000
Creator: YONAS,GEROLD & MOY,TIMOTHY DAVID
System: The UNT Digital Library
Fabrication of Yb-123 Tapes (open access)

Fabrication of Yb-123 Tapes

While Bi-2223 tapes have been the workhorses of the superconductor industry, their poor performance in applied magnetic fields restrict their use to below 30 K. Melt-processing of Ag-clad Yb-123 PIT tapes offers a simple and scalable technique for fabricating long-length HTS conductors capable of being used at 77 K. Under reduced oxygen partial pressure, the peritectic temperature of Yb-123 is below the melting point of Ag, and this facilitates the adaptation of melt-texturing methods for fabricating these tapes. The effect of melt-processing temperature on current density was also explored; a temperature of 965 C yielded optimal critical current values. The critical current density achieved at 4.2 K was 20,000 A/cm{sup 2}, corresponding to a critical current of 52 A. Based on the above results, an optimal processing zone for melt-processing of Ag-clad Yb-123 tapes was determined. These results hold promise for melt-processing of Ag-clad Yb-123 tapes as an alternative to Bi-2223 PIT technology.
Date: November 15, 2000
Creator: Athur, S.; Balachandran, U. & Salama, K.
System: The UNT Digital Library
Fast Particle Effects on the Internal Kink, Fishbone and Alfven Modes (open access)

Fast Particle Effects on the Internal Kink, Fishbone and Alfven Modes

The issues of linear stability of low frequency perturbative and nonperturbative modes in advanced tokamak regimes are addressed based on recent developments in theory, computational methods, and progress in experiments. Perturbative codes NOVA and ORBIT are used to calculate the effects of TAEs on fast particle population in spherical tokamak NSTX. Nonperturbative analysis of chirping frequency modes in experiments on TFTR and JT-60U is presented using the kinetic code HINST, which identified such modes as a separate branch of Alfven modes - resonance TAE (R-TAE). Internal kink mode stability in the presence of fast particles is studied using the NOVA code and hybrid kinetic-MHD nonlinear code M3D.
Date: November 15, 2000
Creator: Gorelenkov, N. N.; Bernabei, S.; Cheng, C. Z.; Fu, G. Y.; Hill, K.; Kaye, S. et al.
System: The UNT Digital Library
Flibe assessments. (open access)

Flibe assessments.

An assessment of the issues on using flibe for fusion applications has been made. It is concluded that sufficient tritium breeding can be achieved for a flibe blanket, especially if a few cm of Be is include in the blanket design. A key issue is the control of the transmutation products such as TF and F{sub 2}. A REDOX (Reducing-Oxidation) reaction has to be demonstrated which is compatible to the blanket design. Also, MHD may have strong impact on heat transfer if the flow is perpendicular to the magnetic field. The issues associated with the REDOX reaction and the MHD issues have to be resolved by both experimental program and numerical solutions.
Date: November 15, 2000
Creator: Sze, D. K.; McCarthy, K.; Sawan, M.; Tillack, M.; Ying, A. & Zinkle, S.
System: The UNT Digital Library
Flibe blanket concept for transmuting transuranic elements and long lived fission products. (open access)

Flibe blanket concept for transmuting transuranic elements and long lived fission products.

A Molten salt (Flibe) fusion blanket concept has been developed to solve the disposition problems of the spent nuclear fuel and the transuranic elements. This blanket concept can achieve the top rated solution, the complete elimination of the transuranic elements and the long-lived fission products. Small driven fusion devices with low neutron wall loading and low neutron fluence can perform this function. A 344-MW integrated fusion power from D-T plasmas for thirty years with an availability factor of 0.75 can dispose of 70,000 tons of the US inventory of spent nuclear fuel generated up to the year 2015. In addition, the utilization of this blanket concept eliminates the need for a geological repository site, which is a major advantage. This application provides an excellent opportunity to develop and to enhance the public acceptance of the fusion energy for the future. The energy from the transmutation process is utilized to produce revenue. Flibe, lithium-lead eutectic, and liquid lead are possible candidates. The liquid blankets have several features, which are suited for W application. It can operate at constant thermal power without interruption for refueling by adjusting the concentration of the transuranic elements and lithium-6. These liquids operate at low-pressure, which reduces …
Date: November 15, 2000
Creator: Gohar, Y.
System: The UNT Digital Library
Global Stability of the Field Reversed Configuration (open access)

Global Stability of the Field Reversed Configuration

New computational results are presented which provide a theoretical basis for the stability of the Field Reversed Configuration (FRC). The FRC is a compact toroid with negligible toroidal field in which the plasma is confined by a poloidal magnetic field associated with toroidal diamagnetic current. Although many MHD modes are predicted to be unstable, FRCs have been produced successfully by several formation techniques and show surprising macroscopic resilience. In order to understand this discrepancy, we have developed a new 3D nonlinear hybrid code (kinetic ions and fluid electrons), M3D-B, which is used to study the role of kinetic effects on the n = 1 tilt and higher n modes in the FRC. Our simulations show that there is a reduction in the tilt mode growth rate in the kinetic regime, but no absolute stabilization has been found for s bar less than or approximately equal to 1, where s bar is the approximate number of ion gyroradii between the field null and the separatrix. However, at low values of s bar, the instabilities saturate nonlinearly through a combination of a lengthening of the initial equilibrium and a modification of the ion distribution function. These saturated states persist for many Alfven …
Date: November 15, 2000
Creator: Belova, E. V.; Jardin, S. C.; Ji, H.; Kulsrud, R. M.; Park, W. & Yamada, M.
System: The UNT Digital Library
Impact of transmutations in fusion environment on Flibe chemistry. (open access)

Impact of transmutations in fusion environment on Flibe chemistry.

Transmutation rates of Li, Be and F are calculated for a typical flibe blanket. The results concluded that the transmutation rate of F is more than double that of Be. Because of the high destruction rate of fluorine, there will be no free fluorine in the molten salt. Therefore, experimental program to address the chemistry control of flibe does not have to worry about the issues associated with free fluorine. Also, this calculation defines the chemical of flibe after irradiation. This chemical state needs to be simulated closely for the flibe chemistry control experiment.
Date: November 15, 2000
Creator: Sze, D. K.; Sawan, M. E. & Cheng, E. T.
System: The UNT Digital Library
Improvement of JT-60U Negative Ion Source Performance (open access)

Improvement of JT-60U Negative Ion Source Performance

The negative ion neutral beam system now operating on JT-60U was the first application of negative ion technology to the production of beams of high current and power for conversion to neutral beams, and has successfully demonstrated the feasibility of negative ion beam heating systems for ITER and future tokamak reactors [1, 2]. It also demonstrated significant electron heating[3] and high current drive efficiency in JT-60U[4]. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. We have explored the physical mechanisms responsible for these processes, and implemented solutions for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and nonuniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roug hly a third, and permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density, and in coping with the sensitivity of the cesium in the ion sources to oxidation by tiny air or water leaks, and the …
Date: November 15, 2000
Creator: Grisham, L. R.; Kuriyama, M.; Kawai, M.; Itoh, T.; Umeda, N. & Team, JT-60U
System: The UNT Digital Library
Investigation of Hypergolic Fuels with Hydrogen Peroxide (open access)

Investigation of Hypergolic Fuels with Hydrogen Peroxide

None
Date: November 15, 2000
Creator: MELOF,BRIAN M. & GRUBELICH,MARK C.
System: The UNT Digital Library
Liquid Lithium Experiments in CDX-U (open access)

Liquid Lithium Experiments in CDX-U

The initial results of experiments involving the use of liquid lithium as a plasma facing component in the Current Drive Experiment-Upgrade (CDX-U) are reported. Studies of the interaction of a steady-state plasma with liquid lithium in the Plasma Interaction with Surface and Components Experimental Simulator (PISCES-B) are also summarized. In CDX-U a solid or liquid lithium covered rail limiter was introduced as the primary limiting surface for spherical torus discharges. Deuterium recycling was observed to be reduced, but so far not eliminated, for glow discharge-cleaned lithium surfaces. Some lithium influx was observed during tokamak operation. The PISCES-B results indicate that the rates of plasma erosion of lithium can exceed predictions by an order of magnitude at elevated temperatures. Plans to extend the CDX-U experiments to large area liquid lithium toroidal belt limiters are also described.
Date: November 15, 2000
Creator: Majeski, R.; Doerner, R.; Kaita, R.; Antar, G.; Timberlake, J. & al, et
System: The UNT Digital Library
Local Physics Basis of Confinement Degradation in JET ELMy H-Mode Plasmas and Implications for Tokamak Reactors (open access)

Local Physics Basis of Confinement Degradation in JET ELMy H-Mode Plasmas and Implications for Tokamak Reactors

ELMy H-mode plasmas form the basis of conservative performance predictions for tokalmak reactors of the size of ITER. Relatively high performace for long durations has been achieved and the scaling is favorable. It will be necessary to sustain low Zeff and high density for high fusion yield. This paper studies the degradation in confinement and increase in the anomalous heat transport observed in two JET plasmas: one in which the degradation occurs with an intense gas puff, and the other with a spontaneous transition at the heating power threshold from Type I to III ELMs. Linear gryokinetic analysis gives the growth rate, glin of the fastest growing mode. Our results indicate that the flow-shearing rate wExB and glin are large near the top of the pedestal. Their ratio decreases approximately when the confinement degrades and the transport increases. This suggests that tokamak reactors may require intense toroidal or poloidal torque input to maintain sufficiently high *wExB*/glin near the top of the pedestal for high confinement.
Date: November 15, 2000
Creator: Budny, R.V.
System: The UNT Digital Library