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
Object Type: Report
System: The UNT Digital Library
Double K-vacancy production by x-ray photoionization. (open access)

Double K-vacancy production by x-ray photoionization.

We have studied double K-shell photoionization of Ne and Mo (Z = 10 and 42) at the Advanced Photon Source. Double K-vacancy production in Ne was observed by recording the KK-KLL Auger hypersatellite spectrum. Comparison is made with calculations using the multiconfiguration Dirac-Fock method. For Mo, double K-vacancy production was observed by recording the K{alpha}, {beta} fluorescence hypersatellite and satellite x rays in coincidence. From the intensities of the Auger or x-ray hypersatellites relative to diagram lines, the probabilities for double K-vacancy production relative to single K-vacancies were determined. These results, along with reported measurements on other atoms, are compared with Z-scaling calculations of the high-energy limits of the double-to-single K-shell photoionization ratio.
Date: August 13, 2002
Creator: Southworth, S. H.; Dunford, R. W.; Kanter, E. P.; Krassig, B.; Young, L.; Armen, G. B. et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of a CIDI pre-transmission parallel hybrid drivetrain with CVT. (open access)

Evaluation of a CIDI pre-transmission parallel hybrid drivetrain with CVT.

Argonne National Laboratory (ANL) is the lead laboratory for hardware-in-the-loop (HIL) testing and technology validation for the U.S. Department of Energy's Office of Advanced Automotive Technologies (DOE OAAT). In this role, ANL contributes to DOE OAAT goals by setting technical targets and evaluating new technologies in a vehicle systems context, with a focus on hybrid electric vehicle (HEV) technology. ANL employs a unique integrated process based on powerful simulation tools and experimental facilities to perform system-level tests quickly and cost-effectively. This approach allows ANL researchers to simulate a vehicle system, design an optimal control strategy, and then apply it to the real components and subsystems being evaluated. The objective is to better understand (1) component/subsystem performance and control requirements in a simulated vehicle environment and (2) the effect of control on emissions and efficiency. This process has been applied to the evaluation of a hybrid powertrain consisting of a Compression-Ignition Direct-Injection (CIDI) engine, an electric traction motor, and a Continuously Variable Transmission (CVT). This paper describes the testing methodology, the building of the powertrain, the control strategy used, and the analysis of results.
Date: August 13, 2002
Creator: Pasquier, M.; Duoba, M.; Hardy, K.; Rousseau, A. & Shimcoski, D.
Object Type: Article
System: The UNT Digital Library
Progress in the fabrication of high aspect ratio zone plates by soft x-ray lithography. (open access)

Progress in the fabrication of high aspect ratio zone plates by soft x-ray lithography.

Soft x-ray lithography technology has been applied to fabrication of phase shifting Fresnel Zone Plate (FZP's) for hard x-rays. Effects of the exposure conditions, developing system, and electroplating process parameters on line width and aspect ratio have been analyzed. The process has been optimized and an aspect ratio of 11 has been achieved for 110 nm outermost zone width. SEM and AFM have been used for preliminary metrology of the FZPs. The FZP optical performance was characterized at 8 keV photon energy at the 2-ID-D beam line at the Advanced Photon Source. Focusing efficiencies of 23% for FZPs apertures to 100 microns and 18% for 150-micron-diameter apertures have been obtained. The parameters of the fabricated FZP are in good agreement with the predicted values.
Date: August 13, 2002
Creator: Divan, R.; Mancini, D. C.; Moldovan, N. A.; Lai, B.; Assoufid, L.; Leondard, Q. et al.
Object Type: Article
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.
Object Type: Report
System: The UNT Digital Library
Transition to a nuclear/hydrogen energy system. (open access)

Transition to a nuclear/hydrogen energy system.

The paper explores the motivation for the transition to a nuclear/hydrogen system. For such a transition to be successful the technologies employed must be able to generate enough hydrogen to displace a significant fraction of the petroleum fuels used in the transportation and process heat sectors. This hydrogen must be generated in a manner that is compatible with the environment and independent of foreign fuels. Nuclear energy, along with contributions from wind, solar, and geothermal resources meet the criteria of environmental compatibility and resource independence. However, nuclear energy is the only one of these sources that has a high enough energy density to generate copious quantities of hydrogen. The status of the relevant nuclear and hydrogen technologies are discussed and how they are coupled to bring about a transition to a nuclear/hydrogen system. Should the world adopt such a system then the growth rate of nuclear energy would greatly accelerate. With an accelerated growth for nuclear energy the uranium resources would be depleted in a few decades with the once through fuel cycle currently in use. It is pointed out that deployment of fast breeder reactors would become important in the nearer term.
Date: August 13, 2002
Creator: Walters, L.; Wade, D. & Lewis, D.
Object Type: Article
System: The UNT Digital Library
An evaluation of a user-level data transfer mechanism for high-performance networks. (open access)

An evaluation of a user-level data transfer mechanism for high-performance networks.

In this paper, we describe FOBS: a simple user-level communication protocol designed to take advantage of the available bandwidth in a high-bandwidth, high-delay network environment. We compare the performance of FOBS with that of TCP both with and without the so-called Large Window extensions designed to improve the performance of TCP in this type of network environment. We show that FOBS can obtain on the order of 90% of the available bandwidth across both short- and long-haul high-performance network connections. For the long-haul connection, the bandwidth obtained was 1.8 times higher than that of the optimized TCP algorithm. Also, we demonstrate that the additional traffic placed on the network because of the greedy nature of the algorithm is quite reasonable, representing approximately 3% of the total data transferred.
Date: August 13, 2002
Creator: Dickens, P. M. & Gropp, W.
Object Type: Article
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.
Object Type: Report
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.
Object Type: Report
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
Object Type: Report
System: The UNT Digital Library
Diffuse scattering sheets in reciprocal space corresponding to Kiessig fringes for x-ray multilayers. (open access)

Diffuse scattering sheets in reciprocal space corresponding to Kiessig fringes for x-ray multilayers.

Synchrotron bending magnet radiation at the Advanced Photon Source was used to measure x-ray diffuse scattering of tungsten/carbon multilayers having period of 28 {angstrom}. Scattering not only near the first Bragg sheet in reciprocal space, but also near sheets corresponding to Kiessig fringes was simulated in the Born approximation. Full roughness propagation starting with the substrate was used in the simulation. We conclude that the differential equation that describes the kinetic roughening during sputtering is second order, i.e., the Langevin equation. For thermal-diffusion-related kinetic roughening either a third- or fourth-order equation should apply, and we conclude that thermal mechanisms for kinetic roughening need not be invoked.
Date: August 13, 2002
Creator: Macrander, A. T.; Chu, Y.; Liu, C. & Mancini, D.
Object Type: Article
System: The UNT Digital Library
Update of Run 1 b results at CDF (open access)

Update of Run 1 b results at CDF

While the Collider Detector at Fermilab (CDF) is starting a new data run, it is also finishing analyses based on the 100 pb{sup -1} ''Run 1'' data sample collected between 1992 and 1996. In particular, the {Lambda}{sub b} lifetime has been measured using the exclusive decay channel {Lambda}{sub b} {yields} J/{psi}{Lambda}{sup 0}. The B{sup +} cross section, based upon the decay B{sup +} {yields} J/{psi}K{sup +}, has been finalized, as well as the ratio of inclusive b quark cross sections at {radical}s = 630 GeV and 1800 GeV. Early results from the new data run with the displaced-track trigger, which shows great promise for b physics at CDF, are presented.
Date: August 13, 2002
Creator: Tseng, J.
Object Type: Article
System: The UNT Digital Library
Applying chimera virtual data concepts to cluster finding in the Sloan Sky Survey (open access)

Applying chimera virtual data concepts to cluster finding in the Sloan Sky Survey

The GriPhyN project is one of several major efforts working to enable large-scale data-intensive computation as a routine scientific tool. GriPhyN focuses in particular on virtual data technologies that allow computational procedures and results to be exploited as community resources so that, for example, scientists can not only run their own computations on raw data, but also discover computational procedures developed by others and data produced by these procedures. A request to retrieve data on a particular cluster might thus either lead to the retrieval of the requested data from a local or remote database or the scheduling of a computation to produce the data.
Date: August 13, 2002
Creator: al., James Annis et
Object Type: Article
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.
Object Type: Report
System: The UNT Digital Library
Magnetic design of large-bore superconducting quadrupoles for the AHF (open access)

Magnetic design of large-bore superconducting quadrupoles for the AHF

The Advanced Hydrotest Facility (AHF), under study by LANL, utilizes large-bore superconducting quadrupole magnets to image protons for radiography of fast events. In this concept, 50-GeV proton bunches pass through a thick object and are imaged by a lens system that analyzes the scattered beam to determine object details. Twelve simultaneous views of the object are obtained using multiple beam lines. The lens system uses two types of quadrupoles: a large bore (48-cm beam aperture) for wide field of view imaging and a smaller bore (23 cm aperture) for higher resolution images. The gradients of the magnets are 10.14 T/m and 18.58 T/m with magnetic lengths of 4.3 m and 3.0 m, respectively. The magnets are sufficiently novel to present a design challenge. Evaluation and comparisons were made for various types of magnet design: shell and racetrack coils, cold and warm iron, as well as an active superconducting screen. Nb{sub 3}Sn cable was also considered as an alternative to avoid quenching under high beam-scattering conditions. The superconducting shield concept eliminates the iron core and greatly lessens the cryogenic energy needed for cool down. Several options are discussed and comparisons are made.
Date: August 13, 2002
Creator: al., Vladimir S Kashikhin et
Object Type: Article
System: The UNT Digital Library
First prototype undulator for the LCLS project - mechanical design and prototype lessons. (open access)

First prototype undulator for the LCLS project - mechanical design and prototype lessons.

The design of a new hybrid-type undulator with a fixed gap of 6 mm, a period of 30 mm, and a length of 3.4 m is presented. The undulator line, consisting of 33 such units, is a critical part of the LCLS project, which is one step toward the design of a fourth-generation synchrotron radiation source. Magnetic tolerance of all 33 undulators, as well as the corresponding mechanical uniformity, is a major challenge. A ridged C-shape design with a titanium housing of 12 inch diameter was chosen to provide easy access to the gap area for magnetic measuring and tuning. Lessons learned while working with this prototype are critical for successful project execution. Assembly and tests results, as well as possible design changes, are presented.
Date: August 13, 2002
Creator: Trakhtenberg, E.; Tcheskidov, V.; Erdmann, M.; Vasserman, I.; Vinokurov, N.; Makarov, O. et al.
Object Type: Article
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.
Object Type: Report
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.
Object Type: Report
System: The UNT Digital Library
Contamination due to memory effects in filtered vacuum arc plasma deposition systems (open access)

Contamination due to memory effects in filtered vacuum arc plasma deposition systems

Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the SRIM (Stopping and Range of Ions in Matter) code. We find film contamination of order 10-4 - 10-3, and the memory of the prior history of the deposition hardware can be relatively long-lasting.
Date: August 13, 2002
Creator: Martins, D. R.; Salvadori, M. C.; Verdonck, P. & Brown, I. G.
Object Type: Article
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
Object Type: Report
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
Object Type: Report
System: The UNT Digital Library