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Occupied and unoccupied orbitals of C{sub 60} and C{sub 70}

Description: The full spectrum of occupied and unoccupied {sigma} and {pi} orbitals is presented for solid C{sub 60}, C{sub 70}, and graphite, using Cls emission and absorption spectroscopy. There are significant differences between C{sub 60} and C{sub 70}, and even larger changes relative to their infinite analog graphite C{sub {infinity}}. A comparison is made with photoemission and inverse photoemission results, along with first principles quasiparticle calculations.
Date: March 8, 1994
Creator: Carlisle, J. A.; Terminello, L. J. & Hudson, E. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Optical properties of silicon clusters deposited on the basal plane of graphite

Description: Laser ablation was used to deposit of silicon on highly oriented pyrolytic graphite surfaces in an ultra high-vacuum environment equipped with Auger electron spectroscopy (AES), scanning tunneling microscopy (STM) and luminescence spectroscopy. For deposition of up to several monolayers, post annealing produced silicon clusters, whose size distribution was determined vs annealing time and temperature using STM. Pure silicon clusters ranging from 1 to 10 nm showed no detectable photoluminescence… more
Date: April 1, 1994
Creator: Dinh, L. N.; Chase, L. L.; Balooch, M.; Terminello, L. J.; Tench, R. J. & Wooten, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Mechanisms of mechanical fatigue in ceramics. Annual technical progress report No. 4, August 15, 1992--August 14, 1993

Description: This report covers work done in the second year of the three-year follow-on contract. Theme of our work in this period continued to be the theory and measurement of rate-dependent bridging phenomena in fracture and fatigue. This covers both room temperature phenomena such as cycle-dependent attrition of crack bridging ligaments and high temperature phenomena such as viscosity and creep in bridging or cohesive zones. Our theoretical work focused on analytical solutions to rate dependent bridging… more
Date: July 1, 1994
Creator: Cox, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Boron carbide-based coatings on graphite for plasma facing components

Description: In the effort to evaluate boron-rich coatings as plasma facing surfaces in fusion devices, a new process for applying boron carbide (B{sub 4}C) coatings to graphite was developed. The process entails eutectic melting of the carbon (C) substrate surface with a precursor layer of B{sub 4}C particles. Adherent coatings were achieved which consisted of two layers: a surface layer and a graded penetration zone in the outer portion of the substrate. The surface-layer microstructure was multiphase and… more
Date: January 1, 1994
Creator: Valentine, P. G.; Trester, P. W.; Winter, J.; Linke, J.; Duwe, R.; Wallura, E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The gas turbine-modular helium reactor (GT-MHR), high efficiency, cost competitive, nuclear energy for the next century

Description: The Gas Turbine-Modular Helium Reactor (GT-MHR) is the result of coupling the evolution of a small passively safe reactor with key technology developments in the US during the last decade: large industrial gas turbines, large active magnetic bearings, and compact, highly effective plate-fin heat exchangers. The GT-MHR is the only reactor concept which provides a step increase in economic performance combined with increased safety. This is accomplished through its unique utilization of the Brayt… more
Date: April 1, 1994
Creator: Zgliczynski, J. B.; Silady, F. A. & Neylan, A. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Heat source technology programs: Monthly progress report, April 1994

Description: This monthly report describes activities performed in support of Cassini fueled-clad production and studies related to the use of {sup 238}PuO{sub 2} in radioisotope power systems carried out for the Office of Special Applications of the US Department of Energy (DOE) by Los Alamos National Laboratory (LANL). Most of the activities described are ongoing; the results and conclusion described may change as the work progresses.
Date: September 1, 1994
Creator: George, T. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Assessment of Database for Interaction of Tritium With ITER Plasma Facing Materials

Description: The present work surveys recent literature on hydrogen isotope interactions with Be, SS and Inconels, Cu, C, and V, and alloys of Cu and V. The goals are (1) to provide input to the International Thermonuclear Experimental Reactor (ITER) team to help with tritium source term estimates for the Early Safety and Environmental Characterization Study and (2) to provide guidance for planning additional research that will be needed to fill gaps in the present materials database. Properties of diffusiv… more
Date: September 1994
Creator: Dolan, T. J. & Anderl, R. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Destruction of nuclear graphite using closed chamber incineration

Description: Closed chamber incineration (CCI) is a novel technique by which irradiated nuclear graphite may be destroyed without the risk of radioactive cation release into the environment. The process utilizes an enclosed combustion chamber coupled with molten carbonate fuel cells (MCFCs). The transport of cations is intrinsically suppressed by the MCFCs, such that only the combustion gases are conducted through for release to the environment. An example CCI design was developed which had as its goal the … more
Date: March 1, 1994
Creator: Senor, D. J.; Hollenberg, G. W.; Morgan, W. C. & Marianowski, L. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fundamental and exploratory studies of catalytic steam gasification of carbonaceous materials. Final report, fiscal years 1985--1994

Description: The major purpose of this project was to find catalysts which will permit steam gasification of carbonaceous material at reasonable rates and at lower temperatures than currently practiced. Rapid catalyst deactivation must be avoided. An understanding of the catalytic mechanism is necessary to provide leads towards this aim. This report describes the gasification of graphite studies and the gasification of coals, chars, and petroleum cokes.
Date: March 1, 1994
Creator: Heinemann, H. & Somorjai, G. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Recent DIII-D high power heating and current drive experiments

Description: This paper describes recent DIII-D high power heating and current drive experiments. Describes are experiments with improved wall conditioning, divertor particle pumping, radiative divertor experiments, studies of plasma shape and high poloidal beta.
Date: February 1, 1994
Creator: Simonen, T. C.; Jackson, G. L.; Mahdavi, M. A.; Petrie, T. W.; Politzer, P. A.; Taylor, T. S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Accelerated hygrothermal stabilization of composite materials

Description: Experimentation validated a simple moisture conditioning scheme to prepare Gr/Ep composite parts for precision applications by measuring dimensional changes over 90 days. It was shown that an elevated temperature moisture conditioning scheme produced a dimensionally stable part from which precision structures could be built/machined without significant moisture induced dimensional changes after fabrication. Conversely, that unconditioned Gr/Ep composite panels exhibited unacceptably large dimen… more
Date: May 1, 1994
Creator: Gale, J. A.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Adsorption and diffusion of fluids in well-characterized adsorbent materials. [Annual] progress report, August 1, 1993--July 31, 1994

Description: During this period, work has included molecular simulations for simple gases in well-characterized materials (carbons, aluminophosphates, buckytubes, pillared clays, MCM-41 zeolite), water in carbons and aluminophosphates, and chain molecules in carbons.
Date: August 1, 1994
Creator: Gubbins, K. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Alpha-particle emission from carbon bombarded with neutrons below 30 MeV

Description: Alpha-particle emission induced by neutron bombardment of carbon has been studied from threshold to over 30 MeV using the spallation neutron source at WNR/LAMPF. Targets include thin foils of CH{sub 2} and thicker foils of CH and polycrystalline graphite. Comparisons are made with evaluated data. Values for KERMA (kinetic energy released in materials) based on the results will be presented and compared with those obtained through other experimental approaches.
Date: July 1, 1994
Creator: Haight, R. C.; Lee, T. M. & Sterbenz, S. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Assessing braze quality in the actively cooled Tore Supra Phase III outboard pump limiter

Description: The quality of brazing of pyrolytic graphite armor brazed to copper tubes in Tore Supra`s Phase III Outboard Pump Limiter was assessed through pre-service qualification testing of individual copper/tile assemblies. The evaluation used non-destructive, hot water transient heating tests performed in the high-temperature, high-pressure flow loop at Sandia`s Plasma Materials Test Facility. Surface temperatures of tiles were monitored with an infrared camera as water at 120{degrees}C at about 2.07 M… more
Date: December 31, 1994
Creator: Nygren, R. E.; Lutz, T. L.; Miller, J. D.; McGrath, R. & Dale, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Materials considerations for molten salt accelerator-based plutonium conversion systems

Description: A Molten-Salt Reactor Program for power applications was initiated at the Oak Ridge National Laboratory in 1956. In 1965 the Molten Salt Reactor Experiment (MSRE) went critical and was successfully operated for several years. Operation of the MSRE revealed two deficiencies in the Hastelloy N alloy that had been developed specifically for molten-salt systems. The alloy embrittled at elevated temperatures as a result of exposure to thermal neutrons (radiation damage) and grain boundary embrittlem… more
Date: December 31, 1994
Creator: DeVan, J. H.; DiStefano, J. R.; Eatherly, W. P.; Keiser, J. R. & Klueh, R. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

Description: Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu{sub 2}O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease wit… more
Date: October 1, 1994
Creator: Jernigan, G. G.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Thermal conductivity and thermal expansion of graphite fiber/copper matrix composites

Description: The high specific conductivity of graphite fiber/copper matrix (Gr/Cu) composites offers great potential for high heat flux structures operating at elevated temperatures. To determine the feasibility of applying Gr/Cu composites to high heat flux structures, composite plates were fabricated using unidirectional and cross-plied pitch-based P100 graphite fibers in a pure copper matrix. Thermal conductivity of the composites was measured from room temperature to 1073 K, and thermal expansion was m… more
Date: September 1, 1994
Creator: Ellis, D. L. & McDanels, D. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

Description: Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO… more
Date: September 1, 1994
Creator: Geohegan, D. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Molten fluoride fuel salt chemistry

Description: The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear… more
Date: September 1, 1994
Creator: Toth, L. M.; Del Cul, G. D.; Dai, S. & Metcalf, D. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Interim report on the post irradiation examination of capsules 2 and 3 of the HFR-B1 experiment

Description: This is an interim report on the post irradiation examination (PIE) of capsules 2 and 3 of the HFR-B1 experiment The PIE has been conducted by the Forschungszentrum Juelich and is nearing completion. After disassembly of the capsules, the examination focused on capsule components including fuel compacts, inert compacts fired in different media, graphite cylinders of different grades, unbonded coated fuel particles and unfueled graphite; in addition, heating experiments with intermittent injecti… more
Date: September 1, 1994
Creator: Myers, B. F.; Pott, G.; Schenk, W.; Schroeder, R.; Kuehlein, W.; Buecker, H. J. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High rate PLD of diamond-like-carbon utilizing high repetition rate visible lasers

Description: Pulsed Laser Deposition (PLD) has been shown to be an effective method for producing a wide variety of thin films of high-value-added materials. The high average powers and high pulse repetition frequencies of lasers under development at LLNL make it possible to scale-up PLD processes that have been demonstrated in small systems in a number of university, government, and private laboratories to industrially meaningful, economically feasible technologies. A copper vapor laser system at LLNL has … more
Date: September 15, 1994
Creator: McLean, William, II; Fehring, Edward J.; Dragon, Ernest P. & Warner, Bruce E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Elevated temperature static fatigue of a Nicalon fiber-reinforced SiC composite

Description: Static fatigue tests of a Nicalon fiber-reinforced SiC matrix composite were conducted in four-point bending over a temperature range of 425 to 1,150 C in air at selected stress levels. The composite consisted of a Nicalon cloth with a 0.3 {mu}m graphite interfacial coating and a Forced Chemical Vapor Infiltration (FCVI) SiC matrix composite; samples were tested with or without a final protective SiC seal coat. The results indicated that the fatigue life of the Nicalon-SiC composite decreased w… more
Date: December 31, 1994
Creator: Lin, H. T.; Becher, P. F. & Tortorelli, P. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Effects of particle fueling and plasma wall interactions on DIII-D discharges

Description: DIII-D has successfully operated with an all-graphite first wall, including the first observations of VH-mode without boronization. A major goal of this, and other recent upgrades, was to control impurity influxes and hydrogenic fueling. Graphite tiles were carefully pre-conditioned, first by ex situ preparation and then by baking and helium glow conditioning. No deuterium or hydrogen was used until tokamak operation commenced. With the all graphite wall, both impurity and deuterium influxes du… more
Date: November 1, 1994
Creator: Jackson, G. L.; Baker, D. R.; Holtrop, K. L.; Staebler, G. M.; West, W. P.; Maingi, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ceramic package fabrication for YMP nuclear waste disposal

Description: The purpose of this work is to develop alternate materials/design concepts to metal barriers for the Nevada Nuclear Waste Storage Investigations Project. There is some potential that site conditions may prove to be too aggressive for successful employment of the metal alloys under current consideration or that performance assessment models will predict metal container degradation rates that are inconsistent with the goal of substantially complete containment included in the NRC regulations. In … more
Date: August 1, 1994
Creator: Wilfinger, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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