Local Effects of Biased Electrodes in the Divertor of NSTX (open access)

Local Effects of Biased Electrodes in the Divertor of NSTX

The goal of this paper is to characterize the effects of small non-axisymmetric divertor plate electrodes on the local scrape-off layer plasma. Four small rectangular electrodes were installed into the outer divertor plates of NSTX. When the electrodes were located near the outer divertor strike point and biased positively, there was an increase in the nearby probe currents and probe potentials and an increase in the LiI light emission at the large major radius end of these electrodes. When an electrode located farther outward from the outer divertor strike point was biased positively, there was sometimes a significant decrease in the LiI light emission at the small major radius end of this electrode, but there were no clear effects on the nearby probes. No non-local effects were observed with the biasing of these electrodes.
Date: May 7, 2012
Creator: : S. Zweben, M.D. Campanell, B.C. Lyons, R.J. Maqueda, Y. Raitses, A.L. Roquemore and F. Scotti
Object Type: Report
System: The UNT Digital Library
Search for Extra Dimensions Using Diphoton Events in 7 TeV Proton-Proton Collisions with the ATLAS Detector (open access)

Search for Extra Dimensions Using Diphoton Events in 7 TeV Proton-Proton Collisions with the ATLAS Detector

None
Date: May 7, 2013
Creator: Aad, Georges
Object Type: Article
System: The UNT Digital Library
Intermolecular potential parameters and combining rules determined from viscosity data (open access)

Intermolecular potential parameters and combining rules determined from viscosity data

The Law of Corresponding States has been demonstrated for a number of pure substances and binary mixtures, and provides evidence that the transport properties viscosity and diffusion can be determined from a molecular shape function, often taken to be a Lennard-Jones 12-6 potential, that requires two scaling parameters: a well depth {var_epsilon}{sub ij} and a collision diameter {sigma}{sub ij}, both of which depend on the interacting species i and j. We obtain estimates for {var_epsilon}{sub ij} and {sigma}{sub ij} of interacting species by finding the values that provide the best fit to viscosity data for binary mixtures, and compare these to calculated parameters using several 'combining rules' that have been suggested for determining parameter values for binary collisions from parameter values that describe collisions of like molecules. Different combining rules give different values for {sigma}{sub ij} and {var_epsilon}{sub ij} and for some mixtures the differences between these values and the best-fit parameter values are rather large. There is a curve in ({var_epsilon}{sub ij}, {sigma}{sub ij}) space such that parameter values on the curve generate a calculated viscosity in good agreement with measurements for a pure gas or a binary mixture. The various combining rules produce couples of parameters {var_epsilon}{sub ij}, …
Date: May 7, 2010
Creator: Bastien, Lucas A.J.; Price, Phillip N. & Brown, Nancy J.
Object Type: Article
System: The UNT Digital Library
Synthesis of heterocycles: Indolo (2,1-a) isoquinolines, renewables, and aptamer ligands for cellular imaging (open access)

Synthesis of heterocycles: Indolo (2,1-a) isoquinolines, renewables, and aptamer ligands for cellular imaging

In this thesis, we explore both total syntheses and methodologies of several aromatic heterocyclic molecules. Extensions of the Kraus indole synthesis toward 2-substituted and 2,3-disubstituted indoles, as well as biologically attractive indolo[2,1-a]isoquinolines are described. Recent renewable efforts directed to commodity maleic acid and the first reported furan-based ionic liquids are described. Our total synthesis of mRNA aptamer ligand PDC-Gly, and its dye coupled forms, plus aminoglycoside dye coupled ligands used in molecular imaging, are described.
Date: May 7, 2013
Creator: Beasley, Jonathan
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Discovery of Very High Energy Gamma-Ray Emission from 1FGL J2001.1 4351 by MAGIC (open access)

Discovery of Very High Energy Gamma-Ray Emission from 1FGL J2001.1 4351 by MAGIC

We report the discovery of Very High Energy (VHE; >100 GeV) gamma-ray emission from the source 1FGL J2001.1+4351, (RA 20 01 13.5, dec 43 53 02.8, J2000), which is positionally consistent with the location of the flat spectrum radio source MG4 J200112+4352 (RA 20 01 12.9, dec 43 52 52.8, J2000). The VHE detection is based on a 1.5 hour-long observation performed on July 16th in stereoscopic mode with the two 17m diameter imaging Cherenkov telescopes on La Palma, Canary Islands, Spain. The preliminary analysis of the MAGIC data using the standard cuts optimized for soft energy spectra sources yields a detection of 125 gamma-rays above 90 GeV, corresponding to a pre-trail statistical significance of 7.6 standard deviations. The observed flux is estimated to be {approx}20% of the Crab nebula flux above 100 GeV. Earlier MAGIC observations indicated a substantially lower flux; hence indicating that the source is variable on a few days timescale.
Date: May 7, 2012
Creator: Berger, Karsten; Paneque, David & Giavitto, Gianluca
Object Type: Article
System: The UNT Digital Library
Establishing Natural Product Content with the Natural Radiocarbon Signature (open access)

Establishing Natural Product Content with the Natural Radiocarbon Signature

None
Date: May 7, 2010
Creator: Buchholz, B. A.; Sarachine, M. J. & Zermeno, P.
Object Type: Book
System: The UNT Digital Library
COMPUTATIONAL RESOURCES FOR BIOFUEL FEEDSTOCK SPECIES (open access)

COMPUTATIONAL RESOURCES FOR BIOFUEL FEEDSTOCK SPECIES

While current production of ethanol as a biofuel relies on starch and sugar inputs, it is anticipated that sustainable production of ethanol for biofuel use will utilize lignocellulosic feedstocks. Candidate plant species to be used for lignocellulosic ethanol production include a large number of species within the Grass, Pine and Birch plant families. For these biofuel feedstock species, there are variable amounts of genome sequence resources available, ranging from complete genome sequences (e.g. sorghum, poplar) to transcriptome data sets (e.g. switchgrass, pine). These data sets are not only dispersed in location but also disparate in content. It will be essential to leverage and improve these genomic data sets for the improvement of biofuel feedstock production. The objectives of this project were to provide computational tools and resources for data-mining genome sequence/annotation and large-scale functional genomic datasets available for biofuel feedstock species. We have created a Bioenergy Feedstock Genomics Resource that provides a web-based portal or “clearing house” for genomic data for plant species relevant to biofuel feedstock production. Sequence data from a total of 54 plant species are included in the Bioenergy Feedstock Genomics Resource including model plant species that permit leveraging of knowledge across taxa to biofuel feedstock species.We …
Date: May 7, 2013
Creator: Buell, Carol Robin & Childs, Kevin L
Object Type: Report
System: The UNT Digital Library
Gamma-Ray Band and Multi-Waveband Variability of Blazars with the Fermi Large Area Space Telescope (open access)

Gamma-Ray Band and Multi-Waveband Variability of Blazars with the Fermi Large Area Space Telescope

None
Date: May 7, 2013
Creator: Ciprini, Stefano
Object Type: Article
System: The UNT Digital Library
9978 AND 9975 TYPE B PACKAGING INTERNAL DATA COLLECTION FEASIBILITY TESTING (open access)

9978 AND 9975 TYPE B PACKAGING INTERNAL DATA COLLECTION FEASIBILITY TESTING

The objective of this report is to document the findings from a series of proof-of-concept tests performed by Savannah River National Laboratory (SRNL) R and D Engineering, for the DOE Packaging Certification Program to determine if a viable radio link could be established from within the stainless steel confines of several drum-style DOE certified Type B radioactive materials packagings. Two in-hand, off-the-shelf radio systems were tested. The first system was a Wi-Fi Librestream Onsight{trademark} camera with a Fortress ES820 Access Point and the second was the On-Ramp Wireless Ultra-Link Processing{trademark} (ULP) radio system. These radio systems were tested within the Model 9975 and 9978 Type B packagings at the SRNL. This report documents the test methods and results. A path forward will also be recommended.
Date: May 7, 2012
Creator: Fogle, R.
Object Type: Report
System: The UNT Digital Library
Alcator C-Mod Experiments in Support of the ITER Baseline 15 MA Scenario (open access)

Alcator C-Mod Experiments in Support of the ITER Baseline 15 MA Scenario

Experiments on Alcator C-Mod have addressed several issues for the ITER 15 MA baseline scenario from 2009-2012. Rampup studies show ICRF can save significant V-s, and that an H-mode in the ramp can be utilized to save 50% more. ICRF modifications to li(1) are minimal, although the Te profile is peaked relative to ohmic in the plasma center, and alter sawtooth onset times. Rampdown studies show H-modes can be routinely sustained, avoiding an OH coil over-current associated with the H-L transition, that fast rampdowns are preferred, the density drops with Ip, and that the H-L transition occurs at Ploss/Pthr,LH ~ 1.0-1.3 at n/nGr ~ 0.85. Flattop plasmas targeting ITER baseline parameters have been sustained for 20 τE or 8-13 τCR, but only reach H98 ~ 0.6 at n/nGr = 0.85, rising to 0.9 at n/nGr = 0.65.
Date: May 7, 2013
Creator: Kessel, C.
Object Type: Report
System: The UNT Digital Library
Mobile Ice Nucleus Spectrometer (open access)

Mobile Ice Nucleus Spectrometer

This first year report presents results from a computational fluid dynamics (CFD) study to assess the flow and temperature profiles within the mobile ice nucleus spectrometer.
Date: May 7, 2012
Creator: Kulkarni, Gourihar R. & Kok, G. L.
Object Type: Report
System: The UNT Digital Library
GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESSING CELL WITH MATRIX SIMULANTS AND SUPERNATE (open access)

GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESSING CELL WITH MATRIX SIMULANTS AND SUPERNATE

Savannah River Remediation (SRR) is evaluating changes to its current DWPF flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the CPC since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using …
Date: May 7, 2012
Creator: Lambert, D.; Stone, M.; Newell, J. & Best, D.
Object Type: Report
System: The UNT Digital Library
STELLOPT Modeling of the 3D Diagnostic Response in ITER (open access)

STELLOPT Modeling of the 3D Diagnostic Response in ITER

The ITER three dimensional diagnostic response to an n=3 resonant magnetic perturbation is modeled using the STELLOPT code. The in-vessel coils apply a resonant magnetic perturbation (RMP) fi eld which generates a 4 cm edge displacement from axisymmetry as modeled by the VMEC 3D equilibrium code. Forward modeling of flux loop and magnetic probe response with the DIAGNO code indicates up to 20 % changes in measured plasma signals. Simulated LIDAR measurements of electron temperature indicate 2 cm shifts on the low field side of the plasma. This suggests that the ITER diagnostic will be able to diagnose the 3D structure of the equilibria.
Date: May 7, 2013
Creator: Lazerson, Samuel A
Object Type: Report
System: The UNT Digital Library
LLNL X-band RF System (open access)

LLNL X-band RF System

None
Date: May 7, 2013
Creator: Marsh, R A; Anderson, G G; Anderson, S G; Fisher, S E; Gibson, D J; Hartemann, F V et al.
Object Type: Article
System: The UNT Digital Library
Uncertainty Analysis Technique for OMEGA Dante Measurements (open access)

Uncertainty Analysis Technique for OMEGA Dante Measurements

The Dante is an 18 channel X-ray filtered diode array which records the spectrally and temporally resolved radiation flux from various targets (e.g. hohlraums, etc.) at X-ray energies between 50 eV to 10 keV. It is a main diagnostics installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The absolute flux is determined from the photometric calibration of the X-ray diodes, filters and mirrors and an unfold algorithm. Understanding the errors on this absolute measurement is critical for understanding hohlraum energetic physics. We present a new method for quantifying the uncertainties on the determined flux using a Monte-Carlo parameter variation technique. This technique combines the uncertainties in both the unfold algorithm and the error from the absolute calibration of each channel into a one sigma Gaussian error function. One thousand test voltage sets are created using these error functions and processed by the unfold algorithm to produce individual spectra and fluxes. Statistical methods are applied to the resultant set of fluxes to estimate error bars on the measurements.
Date: May 7, 2010
Creator: May, M J; Widmann, K; Sorce, C; Park, H & Schneider, M
Object Type: Article
System: The UNT Digital Library
Photon Enhanced Thermionic Emission for Solar Energy Harvesting Final Report to the Global Climate and Energy Project (open access)

Photon Enhanced Thermionic Emission for Solar Energy Harvesting Final Report to the Global Climate and Energy Project

None
Date: May 7, 2013
Creator: Melosh, Nicholas; Shen, Zhi-Xun; Schwede, Jared; Riley, Dan; Rosenthal, Samuel; Narasimhan, Vijay et al.
Object Type: Article
System: The UNT Digital Library
High Density Nano-Electrode Array for Radiation Detection (open access)

High Density Nano-Electrode Array for Radiation Detection

Bulk single crystals of Cd1-xZnxTe (x=0.04 to x=0.2) compound semiconductor is used for room temperature radiation detection. The production of large volume of Cd1-xZnxTe with low defect density is expensive. As a result there is a growing research interest in the production of nanostructured compound semiconductors such as Cd1-xZnxTe in an electrochemical route. In this investigation, Cd1-xZnxTe ternary compound semiconductor, referred as CZT, was electrodeposited in the form of nanowires onto a TiO2 nanotubular template from propylene carbonate as the non-aqueous electrolyte, using a pulse-reverse electrodeposition process at 130 ºC. The template acted as a support in growing ordered nanowire of CZT which acts as a one dimensional conductor. Cyclic Voltammogram (CV) studies were conducted in determining the potentials for the growth of nanowires of uniform stoichiometry. The morphologies and composition of CZT were characterized by using SEM, TEM and XRD. The STEM mapping carried out on the nanowires showed the uniform distribution of Cd, Zn and Te elements. TEM image showed that the nanowires were polycrystalline in nature. The Mott-Schottky analysis carried on the nanowires showed that the nanowires were a p-type semiconductor. The carrier density, band gap and resistivity of the Cd0.9Zn0.1Te nanowires were 4.29x1013 cm-3, 1.56 eV …
Date: May 7, 2010
Creator: Misra, Mano
Object Type: Report
System: The UNT Digital Library
The NIF 4.5-m nTOF Detectors (open access)

The NIF 4.5-m nTOF Detectors

The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator/photodetector neutron-time-of-flight (nTOF) detectors for measuring DD and DT neutron yields. The detectors provided consistent neutron yield benchmarks from below 1E9 (DD) to nearly 1E15 (DT). The detectors demonstrated DT yield measurement precisions better than 5%, but the absolute accuracy relies on cross calibration with independent measurements of absolute neutron yield. The 4.5-m nTOF data have provided a useful testbed for testing improvements in nTOF data processing, especially with respect to improving the accuracies of the detector impulse response functions. The resulting improvements in data analysis methods have produced more accurate results. In summary, results from the NIF 4.5-m nTOF detectors have provided consistent measurements of DD and DT neutron yields from laser-fusion implosions.
Date: May 7, 2012
Creator: Moran, M. J.; Bond, E. J.; Clancy, T. J.; Eckart, M. J.; Khater, H. Y. & Glebov, V. Y.
Object Type: Article
System: The UNT Digital Library
Templated synthesis of nickel nanoparticles: Toward heterostructured nanocomposites for efficient hydrogen storage (open access)

Templated synthesis of nickel nanoparticles: Toward heterostructured nanocomposites for efficient hydrogen storage

The world is currently facing an energy and environmental crisis for which new technologies are needed. Development of cost-competitive materials for catalysis and hydrogen storage on-board motor vehicles is crucial to lead subsequent generations into a more sustainable and energy independent future. This thesis presents work toward the scalable synthesis of bimetallic heterostructures that can enable hydrogen to compete with carbonaceous fuels by meeting the necessary gravimetric and volumetric energy densities and by enhancing hydrogen sorption/desorption kinetics near ambient temperatures and pressures. Utilizing the well-known phenomenon of hydrogen spillover, these bimetallic heterostructures could work by lowering the activation energy for hydrogenation and dehydrogenation of metals. Herein, we report a novel method for the scalable synthesis of silica templated zero-valent nickel particles (Ni⊂SiO{sub 2}) that hold promise for the synthesis of nickel nanorods for use in bimetallic heterostructures for hydrogen storage. Our synthesis proceeds by chemical reduction of a nickel-hydrazine complex with sodium borohydride followed by calcination under hydrogen gas to yield silica encapsulated nickel particles. Transmission electron microscopy and powder X-ray diffraction were used to characterize the general morphology of the resultant nanocapsules as well as the crystalline phases of the incorporated Ni{sup 0} nanocrystals. The structures display strong magnetic …
Date: May 7, 2013
Creator: Nelson, Nicholas Cole
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Predicting Image Blur in Proton Radiography: Comparisons Between Measurements and Monte Carlo Simulations (open access)

Predicting Image Blur in Proton Radiography: Comparisons Between Measurements and Monte Carlo Simulations

Given the cost and lead-times involved in high-energy proton radiography, it is prudent to model proposed radiographic experiments to see if the images predicted would return useful information. We recently modified our raytracing transmission radiography modeling code HADES to perform simplified Monte Carlo simulations of the transport of protons in a proton radiography beamline. Beamline objects include the initial diffuser, vacuum magnetic fields, windows, angle-selecting collimators, and objects described as distorted 2D (planar or cylindrical) meshes or as distorted 3D hexahedral meshes. We present an overview of the algorithms used for the modeling and code timings for simulations through typical 2D and 3D meshes. We next calculate expected changes in image blur as scattering materials are placed upstream and downstream of a resolution test object (a 3 mm thick sheet of tantalum, into which 0.4 mm wide slits have been cut), and as the current supplied to the focusing magnets is varied. We compare and contrast the resulting simulations with the results of measurements obtained at the 800 MeV Los Alamos LANSCE Line-C proton radiography facility.
Date: May 7, 2010
Creator: Schach von Wittenau, Alexis E.; Aufderheide, Maurice B., III & Henderson, Gary L.
Object Type: Article
System: The UNT Digital Library
What Scientific Applications can Benefit from Hardware Transactional Memory? (open access)

What Scientific Applications can Benefit from Hardware Transactional Memory?

None
Date: May 7, 2012
Creator: Schindewolf, M; Bihari, B; Gyllenhaal, J; Schulz, M; Wang, A & Karl, W
Object Type: Article
System: The UNT Digital Library
Full toroidal imaging of non-axisymmetric plasma material interaction in the National Spherical Torus eXperiment divertor (open access)

Full toroidal imaging of non-axisymmetric plasma material interaction in the National Spherical Torus eXperiment divertor

None
Date: May 7, 2012
Creator: Scotti, F; Roquemore, A L & Soukhanovskii, V A
Object Type: Article
System: The UNT Digital Library
Diagnostic options for radiative divertor feedback control on NSTX-U (open access)

Diagnostic options for radiative divertor feedback control on NSTX-U

None
Date: May 7, 2012
Creator: Soukhanovskii, V A; Gerhardt, S P; Kaita, R; McLean, A G & Raman, R
Object Type: Article
System: The UNT Digital Library
Enhanced NIF Neutron Activation Diagnostics (open access)

Enhanced NIF Neutron Activation Diagnostics

None
Date: May 7, 2012
Creator: Yeamans, C B; Bleuel, D L & Bernstein, L A
Object Type: Article
System: The UNT Digital Library