38 Matching Results

Results open in a new window/tab.

Surface Characterization of the LCLS RF Gun Cathode (open access)

Surface Characterization of the LCLS RF Gun Cathode

The first copper cathode installed in the LCLS RF gun was used during LCLS commissioning for more than a year. However, after high charge operation (> 500 pC), the cathode showed a decline of quantum efficiency within the area of drive laser illumination. They report results of SEM, XPS and XAS studies that were carried out on this cathode after it was removed from the gun. X-ray absorption and X-ray photoelectron spectroscopy reveal surface contamination by various hydrocarbon compounds. In addition they report on the performance of the second installed cathode with emphasis on the spatial distribution of electron emission.
Date: June 25, 2012
Creator: Brachmann, Axel; /SLAC; Decker, Franz-Josef; /SLAC; Ding, Yuantao; /SLAC et al.
System: The UNT Digital Library
2012 MICROBIAL STRESS RESPONSE GORDON RESEARCH CONFERENCE, JULY 20-25, 2012 (open access)

2012 MICROBIAL STRESS RESPONSE GORDON RESEARCH CONFERENCE, JULY 20-25, 2012

The Gordon Research Conference on MICROBIAL STRESS RESPONSE was held at Mount Holyoke College, South Hadley, Massachusetts, July 15-20, 2012. The Conference was well-attended with 180 participants. The 2012 Microbial Stress Responses Gordon Research Conference will provide a forum for the open reporting of recent discoveries on the diverse mechanisms employed by microbes to respond to stress. Approaches range from analysis at the molecular level (how are signals perceived and transmitted to change gene expression or function) to cellular and microbial community responses. Gordon Research Conferences does not permit publication of meeting proceedings.
Date: July 25, 2012
Creator: Donohue, Timothy
System: The UNT Digital Library
High-harmonic Fast Wave Heating and Current Drive Results for Deuterium H-mode Plasmas in the National Spherical Torus Experiment (open access)

High-harmonic Fast Wave Heating and Current Drive Results for Deuterium H-mode Plasmas in the National Spherical Torus Experiment

A critical research goal for the spherical torus (ST) program is to initiate, ramp-up, and sustain a discharge without using the central solenoid. Simulations of non-solenoidal plasma scenarios in the National Spherical Torus Experiment (NSTX) [1] predict that high-harmonic fast wave (HHFW) heating and current drive (CD) [2] can play an important roll in enabling fully non-inductive (fNI {approx} 1) ST operation. The NSTX fNI {approx} 1 strategy requires 5-6 MW of HHFW power (PRF) to be coupled into a non-inductively generated discharge [3] with a plasma current, Ip {approx} 250-350 kA, driving the plasma into an HHFW H-mode with Ip {approx} 500 kA, a level where 90 keV deuterium neutral beam injection (NBI) can heat the plasma and provide additional CD. The initial approach on NSTX has been to heat Ip {approx} 300 kA, inductively heated, deuterium plasmas with CD phased HHFW power [2], in order to drive the plasma into an H-mode with fNI {approx} 1.
Date: July 25, 2012
Creator: Taylor, G.; Bonoli, P. T.; Harvey, R. W.; Hosea, J. C.; Jaeger, E. F.; LeBlanc, B. P. et al.
System: The UNT Digital Library
Surface Engineering of Corrosion, Environmental Fracture, Cavitation & Impingement Resistant Materials (open access)

Surface Engineering of Corrosion, Environmental Fracture, Cavitation & Impingement Resistant Materials

None
Date: July 25, 2012
Creator: Farmer, J; Rukbenchik, A; Menon, S; McNelley, T & Hackel, L
System: The UNT Digital Library
Synthetic Approaches to (smif)₂Ti (smif=1,3-di-(2-pyridyl)-2-azaallyl) Reveal Redox Non-Innocence and C-C Bond-Formation (open access)

Synthetic Approaches to (smif)₂Ti (smif=1,3-di-(2-pyridyl)-2-azaallyl) Reveal Redox Non-Innocence and C-C Bond-Formation

Article discussing synthetic approaches to (smif)₂Ti(smif=1,3-di-(2-pyridyl)-2-azallyl) revealing redox non-innocence and C-C bond-formation.
Date: July 25, 2012
Creator: Frazier, Brenda A.; Wolczanski, Peter T.; Keresztes, Ivan; DeBeer, Serena 1973-; Lobkovsky, Emil B.; Pierpont, Aaron W. et al.
System: The UNT Digital Library
What Coexists with the Ferromagnetic Metallic Phase in Manganites? (open access)

What Coexists with the Ferromagnetic Metallic Phase in Manganites?

Colossal magnetoresistance, whereby the application of a magnetic field reduces the resistivity of a manganite by orders of magnitude, is generally believed to occur because of coexisting phases. Development of a complete theory to explain the phenomenon requires that the exact nature of these phases be known. We used resonant elastic soft x-ray scattering to examine the superlattice order that exists in La{sub 0.35}Pr{sub 0.275}Ca{sub 0.375}MnO{sub 3} above and below the Curie temperature. By measuring the resonance profile of the scattered x-rays at different values of q, we disentangle the contributions of orbital order and antiferromagnetism to the scattering signal above the Curie temperature. Below the Curie temperature, we see no signal from orbital order, and only antiferromagnetism coexists with the dominant ferromagnetic metallic phase.
Date: July 25, 2012
Creator: Burkhardt, Mark H.; Hossain, M.A.; Sarkar, S.; Achkar, A.J.; Hawthorn, D.G.; Sutarto, R. et al.
System: The UNT Digital Library
Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame (open access)

Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame

Knowledge of eddy currents in the vacuum vessel walls and nearby conducting support structures can significantly contribute to the accuracy of Magnetohydrodynamics (MHD) equilibrium reconstruction in toroidal plasmas. Moreover, the magnetic fields produced by the eddy currents could generate error fields that may give rise to islands at rational surfaces or cause field lines to become chaotic. In the Compact Toroidal Hybrid (CTH) device (R0 = 0.75 m, a = 0.29 m, B ≤ 0.7 T), the primary driver of the eddy currents during the plasma discharge is the changing flux of the ohmic heating transformer. Electromagnetic simulations are used to calculate eddy current paths and profile in the vacuum vessel and in the coil frame pieces with known time dependent currents in the ohmic heating coils. MAXWELL and SPARK codes were used for the Electromagnetic modeling and simulation. MAXWELL code was used for detailed 3D finite-element analysis of the eddy currents in the structures. SPARK code was used to calculate the eddy currents in the structures as modeled with shell/surface elements, with each element representing a current loop. In both cases current filaments representing the eddy currents were prepared for input into VMEC code for MHD equilibrium reconstruction of …
Date: September 25, 2012
Creator: Zolfaghari, A.; Brooks, A; Michaels, A.; Hanson, J. & Hartwell, G.
System: The UNT Digital Library
Contemporary Fraction of bis(2-ethylhexyl) Phthalate in Stilton Cheese by Accelerator Mass Spectrometry (open access)

Contemporary Fraction of bis(2-ethylhexyl) Phthalate in Stilton Cheese by Accelerator Mass Spectrometry

None
Date: September 25, 2012
Creator: Nelson, M. A.; Ondov, J. A.; VanDerveer, M. C. & Buchholz, B. A.
System: The UNT Digital Library
Oxy-Combustion Environment Characterization: Fire- and Steam-Side Corrosion in Advanced Combustion (open access)

Oxy-Combustion Environment Characterization: Fire- and Steam-Side Corrosion in Advanced Combustion

Oxy-fuel combustion is burning a fuel in oxygen rather than air. The low nitrogen flue gas that results is relatively easy to capture CO{sub 2} from for reuse or sequestration. Corrosion issues associated with the environment change (replacement of much of the N{sub 2} with CO{sub 2} and higher sulfur levels) from air- to oxy-firing were examined. Alloys studied included model Fe-Cr alloys and commercial ferritic steels, austenitic steels, and nickel base superalloys. The corrosion behavior is described in terms of corrosion rates, scale morphologies, and scale/ash interactions for the different environmental conditions. Additionally, the progress towards laboratory oxidation tests in advanced ultra-supercritical steam is updated.
Date: September 25, 2012
Creator: Holcomb, G. R.; Tylczak, J.; Meier, G. H.; Lutz, B. S.; Yanar, N. M.; Pettit, F. S. et al.
System: The UNT Digital Library
The Six-Point Remainder Function to all Loop Orders in the Multi-Regge Limit (open access)

The Six-Point Remainder Function to all Loop Orders in the Multi-Regge Limit

None
Date: September 25, 2012
Creator: Pennington, Jeffrey
System: The UNT Digital Library
Study of the e+ e- to Hadrons Via ISR at BaBar (open access)

Study of the e+ e- to Hadrons Via ISR at BaBar

None
Date: September 25, 2012
Creator: Solodov, E. P.
System: The UNT Digital Library
Modeling Dynamic Behavior in Large Evolving Graphs (open access)

Modeling Dynamic Behavior in Large Evolving Graphs

None
Date: October 25, 2012
Creator: Rossi, R. A.; Gallagher, B.; Neville, J. & Henderson, K.
System: The UNT Digital Library
Scattering in Thin Foils Associated with Passive Proton and Ion Beam Focusing (open access)

Scattering in Thin Foils Associated with Passive Proton and Ion Beam Focusing

None
Date: October 25, 2012
Creator: Yuen, A; Lund, S M; Barnard, J J & Cohen, R H
System: The UNT Digital Library
Solubility of 2-Hydroxybenzoic Acid in Water, 1-Propanol, 2-Propanol, and 2-Propanone at (298.2 to 338.2) K and Their Aqueous Binary Mixtures at 298.2 K (open access)

Solubility of 2-Hydroxybenzoic Acid in Water, 1-Propanol, 2-Propanol, and 2-Propanone at (298.2 to 338.2) K and Their Aqueous Binary Mixtures at 298.2 K

Article discussing the solubility of 2-hydroxybenzoic acid in water, 1-propanol, 2-propanol, and 2-propanone at (298.2 to 338.2) K and their aqueous binary mixtures at 298.2 K.
Date: October 25, 2012
Creator: Fakhree, Mohammad Amin Abolghassemi; Ahmadian, Somaieh; Panahi-Azar, Vahid; Jouyban, Abolghasem & Acree, William E. (William Eugene)
System: The UNT Digital Library