Edge Minority Heating Experiment in Alcator C-Mod (open access)

Edge Minority Heating Experiment in Alcator C-Mod

An attempt was made to control global plasma confinement in the Alcator C-Mod tokamak by applying ion cyclotron resonance heating (ICRH) power to the plasma edge in order to deliberately create a minority ion tail loss. In theory, an edge fast ion loss could modify the edge electric field and so stabilize the edge turbulence, which might then reduce the H-mode power threshold or improve the H-mode barrier. However, the experimental result was that edge minority heating resulted in no improvement in the edge plasma parameters or global stored energy, at least at power levels of radio-frequency power is less than or equal to 5.5 MW. A preliminary analysis of these results is presented and some ideas for improvement are discussed.
Date: March 25, 2005
Creator: Zweben, S. J.; Terry, J. L.; Bonoli, P.; Budny, R.; Chang, C. S.; Fiore, C. et al.
Object Type: Report
System: The UNT Digital Library
Genomes, Phylogeny, and Evolutionary Systems Biology (open access)

Genomes, Phylogeny, and Evolutionary Systems Biology

With the completion of the human genome and the growing number of diverse genomes being sequenced, a new age of evolutionary research is currently taking shape. The myriad of technological breakthroughs in biology that are leading to the unification of broad scientific fields such as molecular biology, biochemistry, physics, mathematics and computer science are now known as systems biology. Here I present an overview, with an emphasis on eukaryotes, of how the postgenomics era is adopting comparative approaches that go beyond comparisons among model organisms to shape the nascent field of evolutionary systems biology.
Date: March 25, 2005
Creator: Medina, Monica
Object Type: Article
System: The UNT Digital Library
Parallel Deterministic Neutron Transport with AMR (open access)

Parallel Deterministic Neutron Transport with AMR

AMTRAN, a one, two and three dimensional Sn neutron transport code with adaptive mesh refinement (AMR) has been parallelized with MPI over spatial domains and energy groups and with threads over angles. Block refined AMR is used with linear finite element representations for the fluxes, which are node centered. AMR requirements are determined by minimum mean free path calculations throughout the problem and can provide an order of magnitude or more reduction in zoning requirements for the same level of accuracy, compared to a uniformly zoned problem.
Date: March 25, 2005
Creator: Clouse, C
Object Type: Article
System: The UNT Digital Library
Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment (open access)

Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inherent orbit losses are aggravated by large excursions in the outer gap width during current ramp-up. An investigation of this behavior using various energetic particle diagnostics on NSTX and TRANSP code analysis is presented.
Date: March 25, 2005
Creator: Medley, S. S.; Darrow, D. S.; Liu, D. & Roquemore, A. L.
Object Type: Report
System: The UNT Digital Library
Robust Quantum-Based Interatomic Potentials for Multiscale Modeling in Transition Metals (open access)

Robust Quantum-Based Interatomic Potentials for Multiscale Modeling in Transition Metals

First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in transition metals and alloys within density-functional quantum mechanics. In central bcc transition metals, where multi-ion angular forces are important to structural properties, simplified model GPT or MGPT potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect and mechanical properties at both ambient and extreme conditions. Selected applications to multiscale modeling discussed here include dislocation core structure and mobility, atomistically informed dislocation dynamics simulations of plasticity, and thermoelasticity and high-pressure strength modeling. Recent algorithm improvements have provided a more general matrix representation of MGPT beyond canonical bands, allowing improved accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed for dynamic simulations, and the still-in-progress development of temperature-dependent potentials.
Date: March 25, 2005
Creator: Moriarty, J A; Benedict, L X; Glosli, J N; Hood, R Q; Orlikowski, D A; Patel, M V et al.
Object Type: Article
System: The UNT Digital Library
Savannah River Site Annual Meteorology Report for 2004 (open access)

Savannah River Site Annual Meteorology Report for 2004

Summaries of meteorological observations collected at the Savannah River Site in 2004 show a year that was overall cooler and drier than average. Although the annual rainfall of 42.9 inches was the eleventh driest of all the years over a period of record that began in 1952, rainfall was quite variable through the year. September total rainfall of 10.26 inches was the highest in this 53 year record; conversely, the monthly rainfall in March, 0.81 inches, was the lowest on record. Rainfall of 0.01 inch or more occurred on 104 days during the year. The annual average temperature for 2004, 63.4 degrees F, was the eleventh coldest of any year in an available record that dates to 1964. Cooler than average conditions were observed in 9 of the 12 months of the year. The coldest temperature during the year was 20.3 degrees F on the morning of December 15; the warmest observed temperature was 98.2 degrees F on the afternoon of July 14. The most notable weather event of 2004 was an active Atlantic hurricane season that resulted in six named storms striking the Southeast U.S. during August and September. Although each of these storms posed a significant threat to …
Date: March 25, 2005
Creator: CHARLES, HUNTER
Object Type: Report
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Astrophysics (open access)

Science Day 2005 Poster Abstracts: Astrophysics

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Biology (open access)

Science Day 2005 Poster Abstracts: Biology

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Light and Matter (open access)

Science Day 2005 Poster Abstracts: Light and Matter

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Nuclear Physics (open access)

Science Day 2005 Poster Abstracts: Nuclear Physics

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Theory and Computation (open access)

Science Day 2005 Poster Abstracts: Theory and Computation

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Site-Scale Saturated Zone Transport (open access)

Site-Scale Saturated Zone Transport

None
Date: March 25, 2005
Creator: Sanchez, Paul E.
Object Type: Report
System: The UNT Digital Library