Laser conditioning methods fo hafnia silica multiplayer mirrors (open access)

Laser conditioning methods fo hafnia silica multiplayer mirrors

Large aperture multilayer hafnia silica high reflector coatings at 1064 nm, deposited by reactive electron-beam deposition, were prepared to examine different laser conditioning methods for manufacturing high fluence optics in the National Ignition Facility. Laser conditioning is a process where the damage threshold of the coating is increased or the damage that is created is minimized so that it does not grow upon further irradiation. Two laser conditioning methods were examined for coatings deposited from only oxide starting materials. Off-line laser conditioning consists of raster scanning a mirror past a 1 mm diameter Gaussian beam over the entire clear aperture; a process that takes approximately 24 hours per scan. On-line laser conditioning consisted of a large aperture 300 mm x 300 mm beam from the Beamlet laser that irradiated the entire full clear aperture of a series of mirrors; a process that was limited by a 2-4 hour shot rate. In both cases a six-step process was used with the mirror first irradiated at a low fluence, then successively higher fluences increased in equal increments up to the peak laser operating fluence. Mirrors that were only partially laser conditioned damaged catastrophically while fully conditioned mirrors survived fluences exceeding the safe …
Date: January 6, 1998
Creator: Stolz, C. J.; Sheehan, L. M.; Maricle, S. M.; Schwartz, S.; Kozlowski, M. R.; Jennings, R. T. et al.
Object Type: Article
System: The UNT Digital Library
Machine Tool User Cylindrical Die Rolling Performance Support System (open access)

Machine Tool User Cylindrical Die Rolling Performance Support System

This project was initiated to provide the machine tool industry and the DOE a method for evaluating educating potential users about various aspects of the cylindrical die rolling process including: characteristics of the cylindrical die rolling processes, major productivity and material savings benefits, advantages for use in the fastener industry, production capabilities based on part parameters, and production capabilities based on machine specifications. AlliedSignal Federal Manufacturing and Technologies (ASFM and T) utilized data provided by Kinefac Corporation to develop an interactive performance support system. AlliedSignal developed one complete branch of the program and Kinefac will develop the remaining two branches. Macromedia Authorware version 3.5 and Microsoft Access version 7.0 were selected for development tools. These software tools maximize continued program development ease and program management with future machine technology advancements. Using this authoring tool and the external database resulted in development of a product that has many potential uses within the manufacturing industry. Source code for the product can be used as a template for other applications is reusable and can provide potential solutions to non-manufacturing needs. The final product will be released on CD-ROM.
Date: August 6, 1998
Creator: Bohley, M.C. & Grothe, V.D.
Object Type: Report
System: The UNT Digital Library
Magnetohydrodynamics and Radiation Methods Workshop (open access)

Magnetohydrodynamics and Radiation Methods Workshop

None
Date: August 6, 1998
Creator: Winske, D.
Object Type: Article
System: The UNT Digital Library
Marketing solenoid power saving device. Third quarterly report (open access)

Marketing solenoid power saving device. Third quarterly report

I am continuing to explore three methods of marketing the solenoid power saving device. Since the redesign reported in the last report, we are pursuing both the OEM market, the distributor market in both turf and agricultural areas, and the export market. Progress in these areas is discussed: OEM, distribution; and export.
Date: June 6, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Measurements with radioactive beams at ATLAS. (open access)

Measurements with radioactive beams at ATLAS.

Reactions of interest to nuclear astrophysics have been studied with radioactive beams at the ATLAS accelerator. Using a modified ISOL technique, beams of {sup 18}F (T{sub 1/2} = 110 min) and {sup 56}Ni (T{sub 1/2} = 6.1d) were produced and the reactions {sup 18}F(p,{alpha}){sup 15}O, {sup 18}F(p,{gamma}){sup 19}Ne, and {sup 56}Ni(d,p){sup 57}Ni have been investigated. The results indicate that the {sup 18}F(p,{gamma}) route is a small contributor to the breakout from the hot CNO cycle into the rp process, while the {sup 56}Ni(p,{gamma}){sup 57}Cu rate is about ten times larger than previously assumed.
Date: August 6, 1998
Creator: Rehm, K. E.
Object Type: Article
System: The UNT Digital Library
Measuring the coherence properties of light emission from laser-plasma interactions. Final report (open access)

Measuring the coherence properties of light emission from laser-plasma interactions. Final report

Several detrimental instabilities can be excited when a high-intensity laser interacts with plasma. The temporal evolution and spectra of the scattered light emitted by many of these instabilities are used to characterize the instabilities and to benchmark theories. It has been difficult to image the emission region with sufficient resolution to make quantitative comparisons with theory. Direct measurement of the emission region would yield information on ponderomotive steepening phenomena, the true emission zone of convective instabilities, and on the saturation of absolute instabilities. The increase in laser intensity caused by the filamentation instability is conjectured to elevate the levels of parametric instabilities found in high-energy laser-plasma interactions. Because the diameter of the filaments is very small (on the order of 10 {micro}m), it is impossible to image the emission sites directly and either to prove or to disprove this conjecture. The research reported here examines an alternate method of measuring the emission region of scattered light from parametric instabilities. This report provides a brief background of coherence theory by defining the relevant parameters in Section 2. A concrete example of the effect that multiple scattering sites would have on the proposed measurement is provided in Section 3. The following section …
Date: March 6, 1998
Creator: Batha, S.H.
Object Type: Report
System: The UNT Digital Library
Mercosur: Formation, Status, Trade Effects, Policy Challenges, and U.S. Interests (open access)

Mercosur: Formation, Status, Trade Effects, Policy Challenges, and U.S. Interests

This report examines Mercosur, the third largest preferential trading group in the world. Since its inception in 1991, Mercosur has made considerable progress in integrating the economies of its members. The integration --- an almost complete free trade area and a partial customs union --- has been accompanied by a significant increase in U.S. exports and investment to the region. In the future, Mercosur face challenges affecting the size of its membership, the depth of its integration, and the strength of its institutions.
Date: May 6, 1998
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
Method and Apparatus for measuring Gravitational Acceleration Utilizing a high Temperature Superconducting Bearing (open access)

Method and Apparatus for measuring Gravitational Acceleration Utilizing a high Temperature Superconducting Bearing

Gravitational acceleration is measured in all spatial dimensions with improved sensitivity by utilizing a high temperature superconducting (HTS) gravimeter. The HTS gravimeter is comprised of a permanent magnet suspended in a spaced relationship from a high temperature superconductor, and a cantilever having a mass at its free end is connected to the permanent magnet at its fixed end. The permanent magnet and superconductor combine to form a bearing platform with extremely low frictional losses, and the rotational displacement of the mass is measured to determine gravitational acceleration. Employing a high temperature superconductor component has the significant advantage of having an operative temperature at or below 77K, whereby cooling maybe accomplished with liquid nitrogen.
Date: November 6, 1998
Creator: Hull, John R.
Object Type: Patent
System: The UNT Digital Library
Micro-Fluidic Diffusion Coefficient Measurement (open access)

Micro-Fluidic Diffusion Coefficient Measurement

A new method for diffusion coefficient measurement applicable to micro-fluidics is pre- sented. The method Iltilizes an analytical model describing laminar dispersion in rect- anglllar ~llicro_channe]s. The Illethod ~vas verified throllgh measllremen~ of fllloresceill diffusivity in water and aqueolls polymer solutions of differing concentration. The diffll- sivity of flllorescein was measlmed as 0.64 x 10-gm2/s in water, 0.49 x 10-gm2/s in the 4 gm/dl dextran solution and 0.38 x 10-9n12/s in the 8 gnl/dl dextran solution.
Date: October 6, 1998
Creator: Forster, Fred K. & Galambos, Paul
Object Type: Article
System: The UNT Digital Library
Microbunch Temporal Diagnostic by Compton Scattering in Interfering Laser Beams. (open access)

Microbunch Temporal Diagnostic by Compton Scattering in Interfering Laser Beams.

The exact solution of the classical nonlinear equation of motion for a relativistic electron in the field of two electromagnetic (EM) waves is obtained. For the particular case of the linearly polarized standing EM wave in the planar optical cavity, the intensity of the nonlinear Compton scattering, the time of flight, and the momentum variation after the relativistic electron passes along the cavity axis are calculated in weak and strong field limits. The extent of these effects depends on the initial phase of the EM wave when the electron enters the cavity. This can be used for the production, diagnosis, and acceleration of relativistic electron (positron) microbunches.
Date: July 6, 1998
Creator: Amatuni, Ts. A. & Pogorelsky, I. V.
Object Type: Article
System: The UNT Digital Library
Mn k-edge x-ray absorption spectroscopy (XAS) studies of La{sub 1-x}Sr{sub x}MnO{sub 3}. (open access)

Mn k-edge x-ray absorption spectroscopy (XAS) studies of La{sub 1-x}Sr{sub x}MnO{sub 3}.

Systematic Mn K-edge x-ray absorption spectroscopy (XAS) measurements on samples of La{sub 1{minus}x}Sr{sub x}MnO{sub 3}, which are precursors to colossal magnetoresistive (CMR) materials, are reported. Detailed results on the edge or chemical shift as a function of Sr concentration (hole doping) and sample preparation (air vs oxygen annealed), are discussed. For comparison, a systematic XANES study of the Mn K-edge energy shift, denoting valence change in Mn, has been made in standard manganese oxide systems. Contrary to expectations, the variation in near-edge energies for Mn in La{sub 0.725}Sr{sub 0.275}MnO{sub 3} were small when compared to the difference between that for manganese oxide standards of nominal valence of +3 and +4 (Mn{sub 2}O{sub 3} and MnO{sub 2}).
Date: March 6, 1998
Creator: Mini, S. M.; Mitchell, J.; Hinks, D. G.; Alatas, A.; Rosenmann, D.; Kimball, C. W. et al.
Object Type: Article
System: The UNT Digital Library
Motion description for data compression and classification (open access)

Motion description for data compression and classification

Data compression and processing of image sequences are becoming increasingly important in the era of the information superhighway. This project aims at the development and proof-of-principle of new methods for motion extraction, image sequence compression, and motion analysis. These methods will increase the efficiency of recognition systems and various database applications. The early research into such novel concepts at the forefront of computer vision will benefit LLNL and DOE in all areas associated with archived images and image sequence data. Automated security and surveillance applications are also of special interest in this context. In FY 1997, we started developing a parallel implementation of the face recognition paradigm on the message passing interface (MPI). A parallel implementation is essential to understanding the structure of large image-databases. Our algorithms are now available to interested parties for applications such as scientific data management (SDM). We also are implementing our new algorithms as a growing library of C++ objects. During FY 1997, we focused our research efforts on designing and delivering hardware. In particular, we (1) established the capability to design new retinas and other very-large-scale integrated (VLSI) hardware at LLNL's Institute for Scientific Computing Research (ISCR) and (2) fabricated prototypes through MOSIS, a …
Date: February 6, 1998
Creator: Lades, M
Object Type: Report
System: The UNT Digital Library
Multi-scale electrodynamics (MELD): a CAD tool for photonics analysis and design (open access)

Multi-scale electrodynamics (MELD): a CAD tool for photonics analysis and design

In FY97 we completed work on the (MELD) code, a comprehensive, multiple-length-scale, Graphical User Interface (GUI)-driven photonics design tool. In 1997 MELD was rated one of the one hundred most technologically significant new products of the year by Research and Development magazine.
Date: February 6, 1998
Creator: Ratowsky, R. P.; Kallman, J. S.; Deri, R. J. & Pocha, M. D.
Object Type: Report
System: The UNT Digital Library
Multiple-Group Federal Credit Unions: An Update (open access)

Multiple-Group Federal Credit Unions: An Update

None
Date: May 6, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Multiple-Group Federal Credit Unions: An Update (open access)

Multiple-Group Federal Credit Unions: An Update

None
Date: May 6, 1998
Creator: Smale, Pauline
Object Type: Report
System: The UNT Digital Library

National Education Goals Panel

The National Education Goals Panel (NEGP) is a unique bipartisan and intergovernmental body of federal and state officials created in July 1990 to assess and report state and national progress toward achieving the National Education Goals. Under the legislation, the Panel is charged with a variety of responsibilities to support systemwide reform, including: reporting on national and state progress toward the Goals over a 10-year period; working to establish a system of high academic standards and assessments; identifying actions for federal, state, and local governments to take; and building a nationwide, bipartisan consensus to achieve the Goals.
Date: November 6, 1998
Creator: National Education Goals Panel
Object Type: Website
System: The UNT Digital Library
National Ignition Facility (NIF) operations procedures plan (open access)

National Ignition Facility (NIF) operations procedures plan

The purpose of this Operations Procedures Plan is to establish a standard procedure which outlines how NIF Operations procedures will be developed (i.e , written, edited, reviewed, approved, published, revised) and accessed by the NIF Operations staff who must use procedures in order to accomplish their tasks. In addition, this Plan is designed to provide a guide to the NIF Project staff to assist them in planning and writing procedures. Also, resource and scheduling information is provided.
Date: May 6, 1998
Creator: Mantrom, D.
Object Type: Report
System: The UNT Digital Library
Naturally fractured tight gas reservoir detection optimization (open access)

Naturally fractured tight gas reservoir detection optimization

The previous report provided a detailed summary of the work data on the project at the Rulison field. Key to this report was the finding that the regions where wells showed good EURs were spatially associated with faulting. Specifically, areas considered more permeable due to the presence of natural fractures are generally located in the high-side (footwall) of reverse faults. While this association seems to hold in the Rulison seismic data coverage, this association requires corroboration. Thus the work plan for the quarter of July 1, 1997--September 30, 1997 consisted of three tasks: (1) perform detailed fault mapping of Rulison 3-D seismic data with Barrett Resources; (2) review SOCO 2-D seismic fault mapping and structural interpretations; and (3) initial work into developing a predictive method for locating fault-related natural fractures. The first two tasks were initiated and completed during this reporting period. The work involved required at the collaborative effort between the field operators and ARI staff. The third task marks the beginning of quantitative fracture mechanics analysis of the geologic processes that are involved for the development of fault-related natural fractures. The goal of this work is to develop a predictive capability of locating natural fractures prior to drilling.
Date: February 6, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Nature`s uncommon elements: Plutonium and technetium (open access)

Nature`s uncommon elements: Plutonium and technetium

The authors have taken advantage of the extremely sensitive method of thermal ionization mass spectrometry to measure technetium and plutonium concentrations in sample masses that are smaller by as much as three orders of magnitude than those used in the early research efforts. The work reported in this paper extends the understanding of the geochemistry of plutonium and technetium by developing detailed descriptions of their associations in well characterized geologic samples, and by using modern neutron-transport modeling tools to better interpret the meaning of the results. Analyses were conducted on samples from three uranium ore deposits selected for their contrasting geochemical environments. The Cigar Lake deposit is an unweathered, unaltered primary ore in a reducing environment which is expected to closely approximate a system that is closed with respect to uranium and its products. The Koongarra deposit is a shallow system, both altered and weathered, subject to active ground water flow. Finally, a sample from the Beaverlodge deposit is included because it is a commercially-available uranium ore standard that allows demonstration of the precision of the analytical results.
Date: January 6, 1998
Creator: Curtis, D.; Fabryka-Martin, J.; Dixon, P. & Cramer, J.
Object Type: Report
System: The UNT Digital Library
Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions (open access)

Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions

We investigate the non-equilibrium atomic kinetics using a collisional-radiative (CR) model modified to include line absorption. Steady-state emission is calculated for He-like aluminum ions immersed in a specified radiation field having fixed deviations from a Planck spectrum. The net emission is interpreted in terms of NLTE population changes. The calculation provides an NLTE response matrix, and in agreement with a general relation of non-equilibrium thermodynamics, the response matrix is symmetric. We compute the response matrix for 1% and 50% changes in the photon temperature and find linear response over a surprisingly large range.
Date: January 6, 1998
Creator: More, R.M. & Kato, T.
Object Type: Article
System: The UNT Digital Library
Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions. Revision 1 (open access)

Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions. Revision 1

We investigate non-equilibrium atomic kinetics using a collisional- radiative model modified to include line absorption. Steady-state emission is calculated for He-like aluminum immersed in a specified radiation field having fixed deviations from a Planck spectrum. The calculated net emission is presented as a NLTE response matrix. In agreement with a rigorous general rule of non-equilibrium thermodynamics, the linear response is symmetric. We compute the response matrix for 1% and {+-} 50% changes in the photon temperature and find linear response over a surprisingly large range.
Date: April 6, 1998
Creator: More, R. & Kato, T.
Object Type: Article
System: The UNT Digital Library
New Concepts for High-Intensity PV Modules for Use with Dish Concentrator Systems (open access)

New Concepts for High-Intensity PV Modules for Use with Dish Concentrator Systems

In this paper we report on our efforts to fabricate monolithically interconnected modules (MIMS) from GaAs device structures. The small size of the component cells comprising the MIM allows for operation at very high flux densities. This relaxes the requirement for a small spot-size to be generated by the optics. The devices are grown on semi-insulating substrates, allowing the incorporation of an extremely efficient back surface reflector (BSR). This BSR is an effective tool for thermal management of the array. The possibility of using this device configuration in conjunction with the large dish concentrators developed by the solar thermal community is examined. The advantages of using multijunction devices for this application is also discussed.
Date: October 6, 1998
Creator: Ward, J. S.; Duda, A.; Coutts, T. J. & Kurtz, S. R.
Object Type: Article
System: The UNT Digital Library
A new diffractometer for high energy synchrotron radiation at the elliptical multipole wiggler at the APS. (open access)

A new diffractometer for high energy synchrotron radiation at the elliptical multipole wiggler at the APS.

The use of high energy synchrotrons radiation (above 80 keV) for diffraction experiments offers many advantages resulting from the high penetration depth of the high energy photons and the small Bragg angles. The main features are: the possibility for the study of large sample crystals in transmission geometry, simple sample environments, high instrumental resolution in reciprocal space, the ability to utilize high momentum transfers and small correction factors for scattered intensities. The experiments performed at this kind of diffractometer are mainly flux experiments, in which the only requirement is a relatively small angular divergence for the incident beam in the scattering plane. The new triple crystal diffractometer introduced here will be installed at the elliptical multipole wiggler beamline at the Advanced Photon Source (APS), Because of the high critical energy of this device, 32 keV, the wiggler will produce high intensities at very high photon energies. To collect up to 1 mrad of the horizontal divergence of the beam, a bent annealed silicon monochromator will scatter and focus in the horizontal scattering plane. The diffractometer will be operated in the vertical scattering plane taking advantage of the small vertical beam divergence.
Date: August 6, 1998
Creator: Ruett, U.
Object Type: Article
System: The UNT Digital Library
New Materials for Future Generations of III-V Solar Cells (open access)

New Materials for Future Generations of III-V Solar Cells

Three- and four-junction III-V devices are proposed for ultrahigh-efficiency solar cells using a new 1-eV material lattice-matched to GaAs, namely, GaInNAs. We demonstrate working prototypes of a GaInNAs-based solar cell lattice-matched to GaAs with photoresponse down to 1 eV. Under the AM1.5 direct spectrum with all the light higher in energy than the GaAs band gap filtered out, the prototypes grown with base doping of about 10{sup 17} cm-3 have open-circuit voltages ranging from 0.35 to 0.44 V, short-circuit current densities of 1.8 mA/cm2, and fill factors from 61% to 66%. To improve on the current record-efficiency tandem GaInP/GaAs solar cell by adding a GaInNAs junction, the short-circuit current density of this 1-eV cell must be significantly increased. Because these low short-circuit current densities are due to short diffusion lengths, we have demonstrated a depletion-width-enhanced variation of one of the prototype devices that trades off decreased voltage for increased photocurrent, with a short-circuit current density of 7.4 mA/cm2 and an open-circuit voltage of 0.28 V.
Date: October 6, 1998
Creator: Geisz, J. F.; Friedman, D. J.; Olson, J. M.; Kramer, C.; Kibbler, A. & Kurtz, S. R.
Object Type: Article
System: The UNT Digital Library