NIF Optical Materials and Fabrication Technologies: An Overview (open access)

NIF Optical Materials and Fabrication Technologies: An Overview

The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design. A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of spatial scale-lengths from 10 {micro}m to 0.5 m (full aperture). We have continued our multi-year research effort to improve the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems. Research …
Date: February 23, 2004
Creator: Campbell, J. H.; Hawley-Fedder, R. A.; Stolz, C. J.; Menapace, J. A.; Borden, M. R.; Whitman, P. K. et al.
Object Type: Article
System: The UNT Digital Library
HyperFlow Theory Manual (open access)

HyperFlow Theory Manual

This document presents the underlying theory for an unsteady computational model of the transient aerothermodynamics of a deformable vehicle entering an atmosphere at hypersonic speeds. Many unique features of the problem require unusual computational capabilities. The large accelerations associated with the vehicle's flight dynamics results in the body-fixed reference frame being non-inertial, and the governing equations must be modified to include this effect. The vehicle's structural deformations and ablation requires the inclusion of the effects of a moving solid boundary, with a nonuniform mass flux across that boundary. A computational chemistry capability must be included to treat the thermochemical nonequilibrium of the high-temperature gas dynamics, and the reactions between the ablation products and the dissociated air. The theory required to treat these phenomena are described in this report.
Date: February 23, 2004
Creator: Felker, F F
Object Type: Report
System: The UNT Digital Library
Computation of Hypersonic Flow about Maneuvering Vehicles with Changing Shapes (open access)

Computation of Hypersonic Flow about Maneuvering Vehicles with Changing Shapes

Vehicles moving at hypersonic speeds have great importance to the National Security. Ballistic missile re-entry vehicles (RV's) travel at hypersonic speeds, as do missile defense intercept vehicles. Despite the importance of the problem, no computational analysis method is available to predict the aerodynamic environment of maneuvering hypersonic vehicles, and no analysis is available to predict the transient effects of their shape changes. The present state-of-the-art for hypersonic flow calculations typically still considers steady flow about fixed shapes. Additionally, with present computational methods, it is not possible to compute the entire transient structural and thermal loads for a re-entry vehicle. The objective of this research is to provide the required theoretical development and a computational analysis tool for calculating the hypersonic flow about maneuvering, deforming RV's. This key enabling technology will allow the development of a complete multi-mechanics simulation of the entire RV flight sequence, including important transient effects such as complex flight dynamics. This will allow the computation of the as-delivered state of the payload in both normal and unusual operational environments. This new analysis capability could also provide the ability to predict the nonlinear, transient behavior of endo-atmospheric missile interceptor vehicles to the input of advanced control systems. Due …
Date: February 23, 2004
Creator: Ferencz, R M; Felker, F F & Castillo, V M
Object Type: Report
System: The UNT Digital Library
Charge-state distribution and Doppler effect in an expanding photoionized plasma (open access)

Charge-state distribution and Doppler effect in an expanding photoionized plasma

None
Date: February 23, 2004
Creator: Foord, M E; Heeter, R F; Thoe, R S; Chung, H; Liedahl, D A; Goldstein, W H et al.
Object Type: Article
System: The UNT Digital Library
Ceramic Membranes for Hydrogen Production From Coal (open access)

Ceramic Membranes for Hydrogen Production From Coal

A technique was developed to extrude thin glass tubes from a glass-polyethersulfone-solvent (NMP) paste with a glass to polymer weight ratio of about 8. The extrudates were gelled in water and heat treated at 800-950 C to remove the polymer and sinter the particles to a dense glass structure. Subsequently, the tubes were leached in hot water to remove the soluble phase formed by phase separation during cooling. The tubes were characterized by XRD, SEM, and permeation measurements. SEM examination indicated that during leaching the glass developed pores of about 100 nm size. Permeation measurements showed lack of separation selectivity consistent with the pore size observed in SEM.
Date: February 23, 2004
Creator: Gavalas, George R.
Object Type: Report
System: The UNT Digital Library
Chloride-mass-balance for predicting increased recharge after land-use change (open access)

Chloride-mass-balance for predicting increased recharge after land-use change

The chloride-mass-balance (CMB) method has been used extensively to estimate recharge in arid and semi-arid environments. Required data include estimates of annual precipitation, total chloride input (from dry fallout and precipitation), and pore-water chloride concentrations. Typically, CMB has been used to estimate ancient recharge but recharge from recent land-use change has also been documented. Recharge rates below a few mm/yr are reliably detected with CMB; however, estimates above a few mm/yr appear to be less reliable. We tested the CMB method against 26 years of drainage from a 7.6-m-deep lysimeter at a simulated waste-burial ground, located on the Department of Energy s Hanford Site in southeastern Washington State, USA where land-use change has increased recharge rates. Measured drainage from the lysimeter for the past 26 years averaged 62 mm/yr. Precipitation averaged 190 mm/yr with an estimated chloride input of 0.225 mg/L. Initial pore-water chloride concentration was 88 mg/L and decreased to about 6 mg/L after 26 years, while the drainage water decreased to less than 1 mg/L. A recharge estimate made using chloride concentrations in drain water was within 20 percent of the measured drainage rate. In contrast, recharge estimates using 1:1 (water: soil) extracts were lower than actual by …
Date: February 23, 2004
Creator: Gee, G. W.; Zhang, Z. F.; Tyler, S. W.; Albright, W. H. & Singleton, M. J.
Object Type: Article
System: The UNT Digital Library
DEVELOPMENT OF A FABRICATION PROCESS FOR SOL-GEL/METAL HYDRIDE COMPOSITE GRANULES (open access)

DEVELOPMENT OF A FABRICATION PROCESS FOR SOL-GEL/METAL HYDRIDE COMPOSITE GRANULES

An external gelation process was developed to produce spherical granules that contain metal hydride particles in a sol-gel matrix. Dimensionally stable granules containing metal hydrides are needed for applications such as hydrogen separation and hydrogen purification that require columns containing metal hydrides. Gases must readily flow through the metal hydride beds in the columns. Metal hydrides reversibly absorb and desorb hydrogen and hydrogen isotopes. This is accompanied by significant volume changes that cause the metal hydride to break apart or decrepitate. Repeated cycling results in very fine metal hydride particles that are difficult to handle and contain. Fine particles tend to settle and pack making it more difficult to flow gases through a metal hydride bed. Furthermore, the metal hydrides can exert a significant force on the containment vessel as they expand. These problems associated with metal hydrides can be eliminated with the granulation process described in this report. Small agglomerates of metal hydride particles and abietic acid (a pore former) were produced and dispersed in a colloidal silica/water suspension to form the feed slurry. Fumed silica was added to increase the viscosity of the feed slurry which helped to keep the agglomerates in suspension. Drops of the feed slurry …
Date: February 23, 2004
Creator: Hansen, E; Eric Frickey, E & Leung Heung, L
Object Type: Report
System: The UNT Digital Library
Application performation evaluation of the HTMT architecture. (open access)

Application performation evaluation of the HTMT architecture.

In this report we summarize findings from a study of the predicted performance of a suite of application codes taken from the research environment and analyzed against a modeling framework for the HTMT architecture. We find that the inward bandwidth of the data vortex may be a limiting factor for some applications. We also find that available memory in the cryogenic layer is a constraining factor in the partitioning of applications into parcels. The architecture in several examples may be inadequately exploited; in particular, applications typically did not capitalize well on the available computational power or data organizational capability in the PIM layers. The application suite provided significant examples of wide excursions from the accepted (if simplified) program execution model--in particular, by required complex in-SPELL synchronization between parcels. The availability of the HTMT-C emulation environment did not contribute significantly to the ability to analyze applications, because of the large gap between the available hardware descriptions and parameters in the modeling framework and the types of data that could be collected via HTMT-C emulation runs. Detailed analysis of application performance, and indeed further credible development of the HTMT-inspired program execution model and system architecture, requires development of much better tools. Chief …
Date: February 23, 2004
Creator: Hereld, M.; Judson, I. R. & Stevens, R.
Object Type: Report
System: The UNT Digital Library
Characterize Framework for Seismicity and Structural Deformation at Yucca Mountain, Nevada (open access)

Characterize Framework for Seismicity and Structural Deformation at Yucca Mountain, Nevada

None
Date: February 23, 2004
Creator: King, J.
Object Type: Report
System: The UNT Digital Library
Translational dynamics of Antifreeze Glycoprotein in supercooled water. (open access)

Translational dynamics of Antifreeze Glycoprotein in supercooled water.

None
Date: February 23, 2004
Creator: Krishnan, V
Object Type: Article
System: The UNT Digital Library
COG validation: SINBAD Benchmark Problems (open access)

COG validation: SINBAD Benchmark Problems

We validated COG, a 3D Monte Carlo radiation transport code, against experimental data and MNCP4C simulations from the Shielding Integral Benchmark Archive Database (SINBAD) compiled by RSICC. We modeled three experiments: the Osaka Nickel and Aluminum sphere experiments conducted at the OKTAVIAN facility, and the liquid oxygen experiment conducted at the FNS facility. COG results are in good agreement with experimental data and generally within a few % of MCNP results. There are several possible sources of discrepancy between MCNP and COG results: (1) the cross-section database versions are different, MCNP uses ENDFB VI 1.1 while COG uses ENDFB VIR7, (2) the code implementations are different, and (3) the models may differ slightly. We also limited the use of variance reduction methods when running the COG version of the problems.
Date: February 23, 2004
Creator: Lent, E M; Sale, K E; Buck, R M & Descalle, M
Object Type: Report
System: The UNT Digital Library
NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS (open access)

NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS

The preparation of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe nano-particle metal loaded mesoporous 1 mm spherical granular {gamma}-Al{sub 2}O{sub 3} catalysts, by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, is accomplished. Parameters for calcination process were optimized using DTA. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the preparations starting with two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). Three sol-gel/oil-drop catalyst preparation methods; (1) Metal nitrate solutions co-entrapped-sol-gel (2) nano-particle metal oxide co-entrapped-sol-gel, and (3) Metal impregnation on preformed alumina granules, were used. Structure and composition of metal-loaded-granules were investigated using XRD, SEM, EDX, and surface area measurements (BET method). The nano-particle nature of catalysts was confirmed using SEM and X-ray diffraction. The reduction efficiency of hydrogenation of catalysts was examined by magnetic studies using a vibrating sample magnetometer (VSM). Catalysts could be effectively calcined at 450 C and the surface area values obtained were between 200-350 m{sup 2}/g, indicating the mesoporous nature of catalyst support. Parameters affecting the metal loading process were also studied, and the optimum conditions were identified and reported for reproducible synthesis of the metal loaded {gamma}-alumina granular particles. The catalyst activities of Fe, Co, and Co/Fe …
Date: February 23, 2004
Creator: Naidu, Seetala V.; Siriwardane, Upali & Murty, Akundi N.
Object Type: Report
System: The UNT Digital Library