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UV laser ionization and electron beam diagnostics for plasma lenses

Description: A comprehensive study of focusing of relativistic electron beams with overdense and underdense plasma lenses requires careful control of plasma density and scale lengths. Plasma lens experiments are planned at the Beam Test Facility of the LBL Center for Beam Physics, using the 50 MeV electron beam delivered by the linac injector from the Advanced Light Source. Here we present results from an interferometric study of plasmas produced in tri-propylamine vapor with a frequency quadrupled Nd:YAG laser at 266 nm. To study temporal dynamics of plasma lenses we have developed an electron beam diagnostic using optical transition radiation to time resolve beam size and divergence. Electron beam ionization of the plasma has also been investigated.
Date: April 1, 1995
Creator: Govil, R.; Volfbeyn, P. & Leemans, W.
Partner: UNT Libraries Government Documents Department

Total energy cycle energy use and emissions of electric vehicles.

Description: A total energy cycle analysis (TECA) of electric vehicles (EV) was recently completed. The EV energy cycle includes production and transport of fuels used in power plants to generate electricity, electricity generation, EV operation, and vehicle and battery manufacture. This paper summarizes the key assumptions and results of the EVTECA. The total energy requirements of EVS me estimated to be 24-35% lower than those of the conventional, gasoline-fueled vehicles they replace, while the reductions in total oil use are even greater: 55-85%. Greenhouse gases (GHG) are 24-37% lower with EVs. EVs reduce total emissions of several criteria air pollutants (VOC, CO, and NO{sub x}) but increase total emissions of others (SO{sub x}, TSP, and lead) over the total energy cycle. Regional emissions are generally reduced with EVs, except possibly SO{sub x}. The limitations of the EVTECA are discussed, and its results are compared with those of other evaluations of EVs. In general, many of the results (particularly the oil use, GHG, VOC, CO, SO{sub x}, and lead results) of the analysis are consistent with those of other evaluations.
Date: April 29, 1999
Creator: Singh, M. K.
Partner: UNT Libraries Government Documents Department

Dynamical hierarchies - A summary

Description: This paper summarizes some of the problems associated with the generation of higher order emergent structures in formal dynamical systems. In biological systems, higher order hyperstructures occur both in an intuitive and a formal sense: monomers, polymers, membranes, organelles, cells, tissues, organs, etc. constitute an observable hierarchy, apparently generated by the underlying biomolecular process. However, in models and simulations of these systems, it has turned out to be quite difficult to produce higher order emergent structures from first principles. The first problem is to agree on what a higher order structure is. An emergent structure can be defined through an introduction of an observational function. If a property can be observed in the dynamics, but not at the level of the fundamental first order interacting structures, we define it to be emergent. It is well known that second order structures occur relatively easy in simulation, so the problem is how to proceed to third and higher order without external interference. A third order structure is defined through the interaction of second order structures forming a new observable not found at the lower levels.
Date: April 1, 1996
Creator: Rasmussen, S.; Barrett, C.L. & Olesen, M.W.
Partner: UNT Libraries Government Documents Department

Properties of H, O and C in GaN

Description: The electrical properties of the light ion impurities H, O and C in GaN have been examined in both as-grown and implanted material. H is found to efficiently passivate acceptors such as Mg, Ca and C. Reactivation occurs at {ge} 450 C and is enhanced by minority carrier injection. The hydrogen does not leave the GaN crystal until > 800 C, and its diffusivity is relatively high ({approximately} 10{sup {minus}11} cm{sup 2}/s) even at low temperatures (< 200 C) during injection by wet etching, boiling in water or plasma exposure. Oxygen shows a low donor activation efficiency when implanted into GaN, with an ionization level of 30--40 meV. It is essentially immobile up to 1,100 C. Carbon can produce low p-type levels (3 {times} 10{sup 17} cm{sup {minus}3}) in GaN during MOMBE, although there is some evidence it may also create n-type conduction in other nitrides.
Date: April 1, 1996
Creator: Pearton, S.J.; Abernathy, C.R. & Lee, J.W.
Partner: UNT Libraries Government Documents Department

Electroforming cell design tool development

Description: The Electroforming Advisor (EFA) team has developed a prototype of an EFA, an easy-to-use design and computational problem solving environment for Electroforming. A primary goal is to enable electroformers to optimally design a cell that would make a part right the first time and with minimum cost. Computer simulations can be carried out much faster than experimentation and without hazardous waste production. The EFA prototype uses the Computer-Aided Design (CAD) and the Computer-Aided Engineering (CAE) capabilities of the Intergraph Engineering Modeling System coupled with the simulation capabilities of a locally developed three-dimensional boundary element code, BEPLATE. 1 ref., 7 figs.
Date: April 1, 1996
Creator: Giles, G.E.
Partner: UNT Libraries Government Documents Department

Design of microwave vitrification systems for radioactive waste

Description: Oak Ridge National Laboratory (ORNL) is involved in the research and development of high-power microwave heating systems for the vitrification of DOE radioactive sludges. Design criteria for a continuous microwave vitrification system capable of processing a surrogate filtercake sludge representative of a typical waste-water treatment operation are discussed. A prototype 915 MHz, 75 kW microwave vitrification system or `microwave melter` is described along with some early experimental results that demonstrate a 4 to 1 volume reduction of a surrogate ORNL filtercake sludge.
Date: April 1, 1996
Creator: White, T.L.; Wilson, C.T.; Schaick, C.R. & Bostick, W.D.
Partner: UNT Libraries Government Documents Department

Humic and fluvic acids and organic colloidal materials in the environment

Description: Humic substances are ubiquitous in the environment, occurring in all soils, waters, and sediments of the ecosphere. Humic substances arise from the decomposition of plant and animal tissues yet are more stable than their precursors. Their size, molecular weight, elemental composition, structure, and the number and position of functional groups vary, depending on the origin and age of the material. Humic and fulvic substances have been studied extensively for more than 200 years; however, much remains unknown regarding their structure and properties. Humic substances are those organic compounds found in the environment that cannot be classified as any other chemical class of compounds. They are traditionally defined according to their solubilities. Fulvic acids are those organic materials that are soluble in water at all pH values. Humic acids are those materials that are insoluble at acidic pH values (pH < 2) but are soluble at higher pH values. Humin is the fraction of natural organic materials that is insoluble in water at all pH values. These definitions reflect the traditional methods for separating the different fractions from the original mixture. The humic content of soils varies from 0 to almost 10%. In surface waters, the humic content, expressed as dissolved organic carbon (DOC), varies from 0.1 to 50 ppm in dark-water swamps. In ocean waters, the DOC varies from 0.5 to 1.2 ppm at the surface, and the DOC in samples from deep groundwaters varies from 0.1 to 10 ppm. In addition, about 10% of the DOC in surface waters is found in suspended matter, either as organic or organically coated inorganic particulates. Humic materials function as surfactants, with the ability to bind both hydrophobic and hydrophyllic materials, making numic and fluvic materials effective agents in transporting both organic and inorganic contaminants in the environment.
Date: April 1996
Creator: Gaffney, J. S.; Marley, N. A. & Clark, S. B.
Partner: UNT Libraries Government Documents Department

A worldwide overview of superconductivity development efforts for utility applications

Description: The progress and prospects for the application of high temperature superconductivity to the electric power sector has been the topic of an IEA Implementing Agreement begun in 1990. The present task members are: Canada, Denmark, Finland, Germany, Israel, Italy, Japan, the Netherlands, Norway, Sweden, Switzerland, Turkey, the United Kingdom, and the United States. As a result of the Implementing Agreement, work has been performed by the Operating Agent with the full participation of all of the member countries. This work has facilitated the exchange of information among experts in all member countries and is the basis for much of the information contained in this paper. This paper summarizes progress toward application of high temperature superconductivity to devices for use in the electric power sector such as: fault-current limiters, cables, superconducting magnetic energy Storage, rotating machinery, transformers, and flywheels incorporating magnetic bearings. Such devices are being designed, built and tested throughout the world.
Date: April 1, 1996
Creator: Giese, R.F.
Partner: UNT Libraries Government Documents Department

Estimating D and D costs for structures at DOE facilities: Some considerations

Description: A number of issues are examined related to estimating decontamination and decommissioning costs for structures at US Department of Energy facilities. The ability to develop detailed estimates for such facilities is generally well established and the general range of costs for such activity is well understood. However, current ability to quickly develop credible planning estimates is more limited. A need exists for a continuing synthesis of experience to allow for an improved ability to develop both detailed and planning estimates.
Date: April 1, 1996
Creator: Davis, M.J.; Folga, S.; Swanston, R. & Janke, R.J.
Partner: UNT Libraries Government Documents Department