Transmission and Propagation of an Accelerating Mode in a Photonic Bandgap Fiber (open access)

Transmission and Propagation of an Accelerating Mode in a Photonic Bandgap Fiber

A hollow core photonic bandgap (PBG) lattice in a dielectric fiber can provide high gradient acceleration in the optical regime, where the accelerating mode resulting from a defect in the PBG fiber can be excited by high-power lasers. Efficient methods of coupling laser power into the PBG fiber are an area of active research. In this paper, we develop a simulation method using the parallel finite-element electromagnetic suite ACE3P to study the propagation of the accelerating mode in the PBG fiber and determine the radiation pattern into free space at the end of the PBG fiber. The far-field radiation will be calculated and the mechanism of coupling power from an experimental laser setup will be discussed.
Date: August 26, 2010
Creator: Ng, C. K.; England, R. J.; Lee, L. Q.; Noble, R.; Rawat, V. & Spencer, J.
Object Type: Article
System: The UNT Digital Library
He Transport and Fate of Tempered Martensitic Steels: Summary of Recent TEM Observations (open access)

He Transport and Fate of Tempered Martensitic Steels: Summary of Recent TEM Observations

As an extension of prior work [1-4], we summarize recent observations made on a He-implanted tempered martensitic steel (TMS), F82H mod 3, irradiated in the HFIR, in both as-tempered (AT) and cold-worked (CW) conditions. A novel implantation technique was used to uniformly inject He into 3-mm diameter TEM discs to depths ranging from ≈ 5-8 µm. The He is generated by two-step transmutation reactions in Ni contained in a NiAl coating layer adjacent to paired 3 mm TEM discs. NiAl layers from 1 to 4 μm thick produced He/dpa ratios between 5 and 40 appm/dpa. The irradiations were at temperatures of 300, 400 and 500°C from 3.9 to 9 dpa and 90 to 380 appm He. Electron transparent samples were prepared by a cross-sectional thinning technique that allowed investigating microstructural evolution over a range of implantation depths. Irradiation of the AT alloy to 9 dpa at 500°C and 380 appm He resulted in relatively large, faceted cavities, that are likely voids, along with a much higher density of smaller He bubbles. The cavities were most often aligned in pearl necklace like strings, presumably due to their formation on pre-existing dislocations. A finer distribution of cavities was also present on precipitate …
Date: February 26, 2010
Creator: Edwards, Danny J.; Kurtz, Richard J.; Odette, G Robert & Yamamoto, Takuya
Object Type: Report
System: The UNT Digital Library
Transport of Heat, Water Vapor and Carbon Doxide by Long Period Eddies in the Stable Boundary Layer (open access)

Transport of Heat, Water Vapor and Carbon Doxide by Long Period Eddies in the Stable Boundary Layer

The vertical transport of heat and trace chemicals for a night in April has been studied with a wavelet analysis and conventional one-hour averages. It was found that for the night of April 20, 2009, turbulent kinetic energy, heat and trace chemicals were transported directed downward from the jet core. The most significant periods for this transport were less than 5 minutes and greater than one hour with intermittent transport taking place in the 5 min to 1 hour time frame. The nocturnal boundary layer is characterized by turbulent intermittency, long period oscillations, and a slow approach to equilibrium, (Mahrt, 1999). Although turbulence is usually maintained by surface friction, downward transport from low-level jets can also play an important role in turbulence maintenance and in the transport of scalars, Mahrt (1999), Banta et al. (2006). The eddy covariance flux measurement technique assumes continuous turbulence which is unusual in the stable boundary because significant flux transport occurs via turbulent eddies whose periods are long compared with the averaging time (Goulden et al., 1996). Systematic error in eddy flux measurements is attributed mainly to the neglect of long period eddies. Banta et al. (2006) noted that observations of turbulence below the low …
Date: July 26, 2010
Creator: Kurzeja, R.
Object Type: Article
System: The UNT Digital Library
Turbulence Considerations for Comparing Ecosystem Exchange over Old-Growth and Clear-Cut Stands with Limited Fetch and Complex Canopy Flows (open access)

Turbulence Considerations for Comparing Ecosystem Exchange over Old-Growth and Clear-Cut Stands with Limited Fetch and Complex Canopy Flows

None
Date: July 26, 2010
Creator: Wharton, S.; Paw U, K. T.; Schroeder, M.; Bible, K. & Falk, M.
Object Type: Article
System: The UNT Digital Library
A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates (open access)

A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates

We construct a 2-leg ladder model of an Fe-pnictide superconductor and discuss its properties and relationship with the familiar 2-leg cuprate model. Our results suggest that the underlying pairing mechanism for the Fe-pnictide superconductors is similar to that for the cuprates.
Date: May 26, 2010
Creator: Berg, E.
Object Type: Article
System: The UNT Digital Library
VERIFICATION SURVEY ACTIVITIES IN FS SURVEY UNITS 7, 8, 9, 10, 11, 13 & 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT (open access)

VERIFICATION SURVEY ACTIVITIES IN FS SURVEY UNITS 7, 8, 9, 10, 11, 13 & 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT

FINAL INTERIM REPORT VERIFICATION SURVEY ACTIVITIES IN FINAL STATUS SURVEY UNITS 7, 8, 9, 10, 11, 13 AND 14 AT THE SEPARATIONS PROCESS RESEARCH UNIT, Niskayuna, New York 0496-SR-03-0. The Separations Process Research Unit (SPRU) facilities were constructed in the late 1940s to research the chemical separation of plutonium and uranium. SPRU operated between February 1950 and October 1953. The research activities ceased following the successful development of the reduction/oxidation and plutonium/uranium extraction processes that were subsequently used by the Hanford and the Savannah River sites.
Date: May 26, 2010
Creator: JADICK, M.G.
Object Type: Report
System: The UNT Digital Library
Verification with gamma-ray and fast neutron detection (open access)

Verification with gamma-ray and fast neutron detection

None
Date: May 26, 2010
Creator: Wurtz, R. E.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Nakae, L. F.; Newby, R. J. et al.
Object Type: Article
System: The UNT Digital Library

Wind Turbine Manufacturers in the United States: Locations and Local Impacts

Suzanne Tegen's presentation about U.S. wind energy manufacturing (presented at WINDPOWER 2010 in Dallas) provides information about challenges to modeling renewables; wind energy's economic "ripple effect"; case studies about wind-related manufacturing in Colorado, Iowa, Ohio, and Indiana; manufacturing maps for the Great Lakes region, Arkansas, and the United States; sample job announcements; and U.S. Treasury Grant 1603 funding.
Date: May 26, 2010
Creator: Tegen, S.
Object Type: Presentation
System: The UNT Digital Library
Zinc Transporter YiiP Escherichia coli (open access)

Zinc Transporter YiiP Escherichia coli

None
Date: March 26, 2010
Creator: Fu, D.
Object Type: Book
System: The UNT Digital Library