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Inertial Fusion Energy Studies on an Earth Simulator-Class Computer (open access)

Inertial Fusion Energy Studies on an Earth Simulator-Class Computer

The U.S. is developing fusion energy based on inertial confinement of the burning fusion fuel, as a complement to the magnetic confinement approach. DOE's Inertial Fusion Energy (IFE) program within the Office of Fusion Energy Sciences (OFES) is coordinated with, and gains leverage from, the much larger Inertial Confinement Fusion program of the National Nuclear Security Administration (NNSA). Advanced plasma and particle beam simulations play a major role in the IFE effort, and the program is well poised to benefit from an Earth Simulator-class resource. Progress in all key physics areas of IFE, including heavy-ion ''drivers'' which impart the energy to the fusion fuel, the targets for both ion- and laser-driven approaches, and an advanced concept known as fast ignition, would be dramatically accelerated by an Earth Simulator-class resource.
Date: August 13, 2002
Creator: Friedman, A & Stephens, R
System: The UNT Digital Library
Analysis of EB support saddles and forces between modules during assembly. (open access)

Analysis of EB support saddles and forces between modules during assembly.

As the EB Tile Calorimeter is constructed, the support saddles and the modules will be subjected to different forces, stresses, and deflections than when completely assembled. The purpose of this analysis is to examine the forces, stresses, and deflections acting on the support saddles and modules at various stages of assembly.
Date: August 13, 2002
Creator: Guarino, V.
System: The UNT Digital Library
Quantum confinement, carrier dynamics and interfacial processes in nanostructured direct/indirect-gap semiconductor-glass composites (open access)

Quantum confinement, carrier dynamics and interfacial processes in nanostructured direct/indirect-gap semiconductor-glass composites

The behavior of semiconductor clusters precipitated in an insulated matrix was investigated. Semiconductor compositions of CdTe, Si and Ge were studies and the insulating matrix was amorphous SiO2. As a function of size, quantum confinement effects were observed in all three composite systems. However significant differences were observed between the direct-gap column 2-6 semiconductors and the indirect-gap column 4 semiconductors. As observed by others, the direct-gap 2-6 semiconductors showed a distinct saturation in the energy-gap blue shift with decreasing size. Theoretical studies using a 20-band k dot p calculation of the electronic and valence bands for a 3-dimensionally confined CdTe semiconductor showed that mixing of the conduction band states leads to a flattening of the central valley. This increases the electron mass drastically and saturates the size dependent blue shift in the bandgap. In contrast, the blue shift in the Si and Ge nanocrystals showed no sign of saturation and increased drastically with decreasing size. In fact, Si and Ge crystals were formed with blue shift values that moved the bandgap to the near UV region. We examined the absorption curves to determine whether the bandgap was direct or indirect in the quantum dots. The results are that the absorption …
Date: August 13, 2002
Creator: Simmons, Joseph H.
System: The UNT Digital Library
Simulations of the Neutral-beam-induced Rotation, Radial Electric Field, and Flow Shearing Rate in Next-step Burning Plasmas (open access)

Simulations of the Neutral-beam-induced Rotation, Radial Electric Field, and Flow Shearing Rate in Next-step Burning Plasmas

Toroidal rotation of plasmas in present tokamaks is beneficial for increasing the stability to wall-induced MHD and appears to reduce the anomalous transport associated with micro-turbulence. This paper calculates the toroidal rotation expected from neutral-beam injection in the proposed FIRE and ITER-FEAT tokamak reactors. Self-consistent burning plasmas for these tokamaks have been constructed using the TRANSP plasma analysis code. Neutral-beam injection has been proposed for FIRE and ITER-FEAT. The neutral-beam-induced torques are computed, and assumptions for the anomalous transport of toroidal angular momentum are used to calculate the toroidal rotation profiles. The central Mach numbers are about 3-8%. The ratio of the rotation speed to the Alfvin speed is less than 1%. Assuming neoclassical poloidal rotation and force balance, the radial electric field and flow shearing rate are calculated. Peak shearing rates near the outboard edge are in the 10-100 krad/s range.
Date: August 13, 2002
Creator: Budny, R.V.
System: The UNT Digital Library
Simulations of Temperatures in Burning Tokamak Plasmas using the GLF23 Model in the TRANSP Code (open access)

Simulations of Temperatures in Burning Tokamak Plasmas using the GLF23 Model in the TRANSP Code

The GLF23 prediction model, incorporated in the TRANSP plasma analysis code, is used to predict temperatures for burning plasmas in the proposed FIRE and ITER-FEAT tokamaks. Flat electron density profiles with various central values are assumed. Scaling of the fusion power P(subscript)dt and gain Q(subscript)dt with density (subscript)and pedestal temperature are given. Helium ash transport and sawtooth effect Pdt in long duration ITER-FEAT plasmas.
Date: August 13, 2002
Creator: Budny, R.V.
System: The UNT Digital Library
Hydraulic performance of a 5-cm CINC contactor for caustic-side solvent extraction. (open access)

Hydraulic performance of a 5-cm CINC contactor for caustic-side solvent extraction.

The hydraulic performance of a 5-cm centrifugal contactor from Costner Industries Nevada Corporation (CINC) was measured for both one- and two-phase flow. Flow conditions and test liquids as well as the liquid height in the annular mixing zone and the occurrence of discontinuous (slug) flow in the interstage lines are reported. Results are compared with earlier results obtained using 2- and 4-cm contactors made at Argonne National Laboratory. In each case, one-phase flow tests can be used to predict behavior in two-phase flow. This makes the one-phase flow test a quality control tool for evaluating contactor rotors as they are manufactured. These results indicate that the 5-cm contactor works in the same way as the 2- and 4-cm contactors.
Date: August 13, 2002
Creator: Leonard, R. A.; Regalbuto, M. C.; Aase, S. B.; Arafat, H. A. & Falkenburg, J. R.
System: The UNT Digital Library
Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and Propulsion Applications (open access)

Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and Propulsion Applications

Any reactor that utilizes fuel consisting of a fissile material in a gaseous state may be referred to as a gaseous core reactor (GCR). Studies on GCRs have primarily been limited to the conceptual phase, mostly due to budget cuts and program cancellations in the early 1970's. A few scientific experiments have been conducted on candidate concepts, primarily of static pressure fissile gas filling a cylindrical or spherical cavity surrounded by a moderating shell, such as beryllium, heavy water, or graphite. The main interest in this area of nuclear power generation is for space applications. The interest in space applications has developed due to the promise of significant enhancement in fuel utilization, safety, plant efficiency, special high-performance features, load-following capabilities, power conversion optimization, and other key aspects of nuclear power generation. The design of a successful GCR adapted for use in space is complicated. The fissile material studied in the pa st has been in a fluorine compound, either a tetrafluoride or a hexafluoride. Both of these molecules have an impact on the structural material used in the making of a GCR. Uranium hexafluoride as a fuel allows for a lower operating temperature, but at temperatures greater than 900K becomes …
Date: August 13, 2002
Creator: Anghaie, Samim
System: The UNT Digital Library
Magnetic Particle Process Improvement (open access)

Magnetic Particle Process Improvement

The magnetic particle testing process is performed to find linear, surface and near surface discontinuities in ferromagnetic test materials. A wet fluorescent method is used at Honeywell Federal Manufacturing & Technologies (FM&T). This method employs a liquid carrier mixed with iron oxide particles in suspension, and the particles used in the method are coated with a fluorescent dye to make them visible under a black light. The process in its current state employs the use of a tank of liquid solution of a mineral oil carrier with iron oxide particles in suspension. The change to the use of an aerosol delivery system with the same material reduces the amount of waste involved in the process while preserving the sensitivity of the testing, shortens the flowtime for the test, and saves labor and material costs.
Date: August 13, 2002
Creator: Hubert, R. R.
System: The UNT Digital Library
Lumber Imports from Canada: Issues and Events (open access)

Lumber Imports from Canada: Issues and Events

This report provides a concise historical account of the dispute, summarizes the subsidy and injury evidence, and discusses the current issues and events regarding lumber imports from Canada.
Date: August 13, 2002
Creator: Gorte, Ross W. & Grimmett, Jeanne
System: The UNT Digital Library
China-U.S. Relations (open access)

China-U.S. Relations

This report discusses the background information and most recent development in U.S.-China relations since mid-1996. Since the early 1990s, U.S.-China relations have followed an uneven course, with modest improvements overshadowed by various recurring difficulties and setbacks. Longstanding bilateral difficulties have included U.S. problems with the PRC’s worsening human rights record, growing tensions over the PRC’s southern military build-up opposite Taiwan and Taiwan’s political status, and continued controversy over allegations of Chinese proliferation of weapons to unstable regimes.
Date: August 13, 2002
Creator: Dumbaugh, Kerry
System: The UNT Digital Library