558 Matching Results

Search Results

Advanced search parameters have been applied.

CHARACTERIZATION OF CORROSION PROBE COUPONS EXPOSED IN TANK 241-AN-107

Description: C-Ring and Pin electrodes from Corrosion Probe retrieved from Tank 241-AN-107 were examined visually and by weight loss measurements. The weight loss measurements were carried out according to ASTM Method G-190. Corrosion rates estimated from the weight loss measurements indicated extremely limited corrosion with no visually observable pitting or cracking. The extremely low corrosion rates are in agreement with the results of ultrasonic examination of the primary tank wall.
Date: December 16, 2003
Creator: Anantatmula, R. P.
Partner: UNT Libraries Government Documents Department

Amorphous and nanocrystalline Mg{sub 2}Si thin film electrodes

Description: Mg{sub 2}Si films, prepared by pulsed laser deposition (PLD), were amorphous, as prepared, and nanocrystalline following annealing. Their micro-structure and electrochemical characteristics were studied by high resolution transmission electron microscopy (HRTEM) and electrochemical cycling against lithium. HRTEM analysis revealed that some excess Si was present in the films. The more amorphous thinner film exhibited excellent cyclability. However, when the film becomes crystalline, the irreversible capacity loss was more significant during the initial cycling and after *50 cycles. Interpretations of the superior stability of the amorphous films are examined.
Date: February 4, 2003
Creator: Song, Seung-Wan; Striebel, Kathryn A.; Song, Xiangyun & Cairns, Elton J.
Partner: UNT Libraries Government Documents Department

Beam dynamics in a storage ring for neutral (polar) molecules

Description: The force from a non-uniform electric field on the electric dipole moment of a molecule may be used to circulate and focus molecules in a storage ring. The nature of the forces from multipole electrodes for bending and focusing are described for strong-field-seeking and for weak-field-seeking molecules. Fringe-field forces are analyzed. Examples of storage ring designs are presented; these include long straight sections and provide bunching and acceleration.
Date: May 1, 2003
Creator: Lambertson, Glen R.
Partner: UNT Libraries Government Documents Department

A Model for the Behavior of Magnetic Tunnel Junctions

Description: A magnetic tunnel junction is a device that changes its electrical resistance with a change in an applied magnetic field. A typical junction consists of two magnetic electrodes separated by a nonmagnetic insulating layer. The magnetizations of the two electrodes can have two possible extreme configurations, parallel and antiparallel. The antiparallel configuration is observed to have the higher measured resistance and the parallel configuration has the lower resistance. To switch between these two configurations a magnetic field is applied to the device which is primarily used to change the orientation of the magnetization of one electrode usually called the free layer, although with sufficient high magnetic field the orientation of the magnetizations of both of the electrodes can be changed. The most commonly used models for describing and explaining the electronic behavior of tunnel junctions are the Simmons model and the Brinkman model. However, both of these models were designed for simple, spin independent tunneling. The Simmons model does not address the issue of applied magnetic fields nor does it address the form of the electronic band structure in the metallic electrodes, including the important factor of spin polarization. The Brinkman model is similar, the main difference between the two models being the shape of the tunneling barrier potential between the two electrodes. Therefore, the research conducted in this thesis has developed a new theoretical model that addresses these important issues starting from basic principles. The main features of the new model include: the development of equations for true spin dependent tunneling through the insulating barrier, the differences in the orientations of the electrode magnetizations on either side of the barrier, and the effects of the density of states function on the behavior of the junction. The present work has explored densities of states that are more realistic than the ...
Date: August 5, 2003
Creator: Baker, Bryan John
Partner: UNT Libraries Government Documents Department

PERFORMANCE DATA OF A PULSED POWER PHOTO INJECTOR.

Description: There has been a lot of interest in compact sources of high brightness, relativistic electron beams. One approach for developing such a source is to apply a high gradient that remains constant during the generation and acceleration of the electron beam. In this paper, we describe high voltage pulse generators that deliver up to 5 MV with 1 ns pulse duration. These devices are synchronizable to an external trigger with jitter of {approx}0.5 ns and can establish gradients in excess of 1 GV/m between two electrodes without breakdown. In the presence of field gradients up to 0.5 GV/m, electron beams of bunch lengths ranging from 1 ns to 0.3 ps and diameter < 300 {micro}m have been generated by irradiating the cathode with UV lasers. Characteristics of these electron beams as well as those produced via field emission at gradients up to 1 GV/m will be discussed.
Date: November 12, 2002
Creator: SMEDLEY,J.; SRINIVASAN - RAO,T.; TSANG,T.; FARRELL,J.P. & BATCHELOR,K.
Partner: UNT Libraries Government Documents Department

Design of Hanford Site 4th Generation Multi Function Corrosion Monitoring System

Description: This document describes the design of the fourth-generation corrosion monitoring system scheduled to be installed in DST 241-AN-104 early in fiscal year 2001. A fourth-generation multi-function corrosion monitoring system has been designed for installation into a DST in the 241-AN farm at the Hanford Site in FY 2001. Improvements and upgrades from the third-generation system (installed in 241-AN-105) that have been incorporated into the fourth-generation system include: Addition of a built-in water lance to assist installation of probe into tanks with a hard crust layer at the surface of the waste; and Improvement of the electrode mounting apparatus used to attach the corrosion monitoring electrodes to the stainless steel probe body (new design simplifies probe assembly/wiring). These new features improve on the third-generation design and yield a system that is easier to fabricate and install, provides for a better understanding of the relationship between corrosion and other tank operating parameters, and optimizes the use of the riser that houses the probe in the tank.
Date: August 30, 2000
Creator: NORMAN, E.C.
Partner: UNT Libraries Government Documents Department

Thin films and surface patterning with BEDT-TTF based charge transfer salts.

Description: Densely covered (ET)X{sub 2} thin films can be selectively electrodeposited on gold electrodes. The insulating (ET)X{sub 2} films are converted to (ET){sub 2}X conductive films through a novel conproportionation reaction. Both ET and ET salt patterns can be prepared with the PDMS stamping technique with use of an ET derivative with a dodecanethiol chain for surface derivatization. These solution procedures open up the possibility to prepare conductive and superconductive charge-transfer salt thin films as well as patterns.
Date: August 21, 2002
Creator: Wang, H. H.; Han, C. Y.; Noh, D.-Y.; Shin, K.-S.; Willing, G. A. & Geiser, U.
Partner: UNT Libraries Government Documents Department

Low Mass Transmission Lines for Z-Pinch Driven Inertial Fusion

Description: Recyclable transmission lines (RTL) are studied as a means of repetitively driving z pinches. The lowest reprocessing costs should be obtained by minimizing the mass of the RTL. Low mass transmission lines (LMTL) could also help reduce the cost of a single shot facility such as the proposed X-1 accelerator and make z-pinch driven space propulsion feasible. We present calculations to determine the minimum LMTL electrode mass to provide sufficient inertia against the magnetic pressure produced by the large currents needed to drive the z pinches. The results indicate an electrode thickness which is much smaller than the resistive skin depth. We have performed experiments to determine if such thin electrodes can efficiently carry the required current. The tests were performed with various thickness of materials. The results indicate that LMTLs should efficiently carry the large z-pinch currents needed for inertial fusion. We also use our results to estimate of the performance of pulsed power driven pulsed nuclear rockets.
Date: January 1, 2002
Creator: SLUTZ, STEPHEN A.; OLSON, CRAIG L. & PETERSON, PER
Partner: UNT Libraries Government Documents Department

Final LDRD Report for the Project Entitled: Biosensors Based on the Electrical Impedance of Tethered Lipid Bilayers on Planar Electrodes

Description: Impedance based, planar chemical microsensors are the easiest sensors to integrate with electronics. The goal of this work is a several order of magnitude increase in the sensitivity of this sensor type. The basic idea is to mimic biological chemical sensors that rely on changes in ion transport across very thin organic membranes (supported Bilayer Membranes: sBLMs) for the sensing. To improve the durability of bilayers we show how they can be supported on planar metal electrodes. The large increase in sensitivity over polyelectrolytes will come from molecular recognition elements like antibodies that bind the analyte molecule. The molecular recognition sites can be tied to the lipid bilayer capacitor membrane and a number of mechanisms can be used to modulate the impedance of the lipid bilayers. These include coupled ion channels, pore modification and double layer capacitance modification by the analyte molecule. The planar geometry of our electrodes allows us to create arrays of sensors on the same chip, which we are calling the ''Lipid Chip''.
Date: February 1, 2003
Creator: HUGHES, ROBERT C.; BRANCH, DARREN W. & BROZIK, SUSAN M.
Partner: UNT Libraries Government Documents Department

Summary report of session VI

Description: This report gives a brief review of the presentations in Session VI of the Ecloud'02 Workshop and summarizes the major points during the discussions. Some points (e.g., the critical mass phenomenon) are not conclusive and even controversial. But it has been agreed that further investigations are warranted. The topic of Session VI in the Ecloud'02 workshop is ''Discussions of future studies, collaborations and possible solutions.'' Half of the session is devoted to presentations, another half to discussions. This report will focus on the latter. There are six presentations: (1) R. Macek, Possible cures to the e-cloud problem; (2) G. Rumolo, Driving the electron-cloud instability by an electron cooler; (3) U. Iriso Ariz, RF test benches for electron-cloud studies; (4) F. Caspers, Stealth clearing electrodes; (5) F. Ruggiero, Future electron-cloud studies at CERN; and (6) E. Perevedentsev, Beam-beam and transverse impedance model.
Date: August 19, 2002
Creator: Chou, Weiren; BrĂ¼ning, O.; Metral, E. & Giovannozzi, M.
Partner: UNT Libraries Government Documents Department

Correlation of Process Data and Electrochemical Noise to Assess Kraft Digester Corrosion: Spring Grove Experiment

Description: Electrochemical noise (ECN) probes were deployed in a carbon steel continuous kraft digester at four locations and at one location in the bottom cone of the associated flash tank. The probes consisted of carbon steel electrodes, representing the vessel construction material, and 309LSi stainless steel overlay electrodes, representing the weld overlay repair in a portion of the vessel. Current and potential noise, the temperature at each probe location, and the value of about 32 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously for a period of almost one year. Historical vessel inspection data and post-test evaluation of the probe components were used to assess/compare ECN corrosion activity with physical changes in wall thickness and corrosion patterns on the digester shell. In addition, attempts were made to correlate ECN activity from each electrode type with process parameters. The results indicate the high general corrosion rates of steel observed just below the extraction screens--on the order of 35 mils/y for the past few years--accelerated further during the period of probe deployment. The maximum wastage of steel (normalized to one full year exposure) was about 85 mils/y at the ring 6N probe just below the extraction screens. Consistent with recent historical observations, the steel corrosion rate at the ring 6S probe--at the same elevation but directly across the digester from ring 6N--was significantly lower at about 50 mils/y. Just prior to probe deployment, the digester shell below the extraction screens was overlaid with 309LSi stainless steel, which was observed to be essentially immune to corrosion at this location. While the ECN probes detected differences in electrochemical behavior between steel probes and between 309LSi probes at rings 6N and 6S, there was only poor quantitative correlation of current sums with actual corrosion rates at these locations. A significant contribution of redox reactions ...
Date: June 18, 2003
Creator: Pawel, S. J.
Partner: UNT Libraries Government Documents Department

Electrocatalytic Materials and Techniques for the Anodic Oxidation of Various Organic Compounds

Description: The focus of this thesis was first to characterize and improve the applicability of Fe(III) and Bi(V) doped PbO{sub 2} film electrodes for use in anodic O-transfer reactions of toxic and waste organic compounds, e.g. phenol, aniline, benzene, and naphthalene. Further, they investigated the use of alternative solution/electrode interfacial excitation techniques to enhance the performance of these electrodes for remediation and electrosynthetic applications. Finally, they have attempted to identify a less toxic metal oxide film that may hold promise for future studies in the electrocatalysis and photoelectrocatalysis of O-transfer reactions using metal oxide film electrodes.
Date: June 27, 2002
Creator: Treimer, Stephen Everett
Partner: UNT Libraries Government Documents Department

Effect of a plume reduction in segmented electrode Hall thruster

Description: A segmented electrode, which is placed at the thruster exit, is shown to affect thruster operation in several ways, whether the electrode produce low emission current or no emission current, although there appear to be advantages to the more emissive segmented electrode. Measured by plume divergence, the performance of Hall thruster operation, even with only one power supply, can approach or surpass that of non segmented operation over a range of parameter regimes, including the low gas rate regime. This allows the flexibility in operation of segmented electrode thrusters in variable thrust regimes.
Date: January 27, 2000
Creator: Raitses, Y.; Dorf, L.A.; Livak, A.A. & Fisch, N.J.
Partner: UNT Libraries Government Documents Department

Ultrasonic Imaging for Poling Uniformity Measurements in PZT Ceramic Elements

Description: This report summarizes the results of a project sponsored by Honeywell Corporation (formerly AlliedSignal Inc.) Federal Manufacturing and Technologies/Kansas City (FM and T/KC) and conducted jointly with the University of Missouri, Rolla, titled ''Ultrasonic Imaging for Poling Uniformity Measurements in PZT Ceramic Elements.'' In this three-month research project, a series of experiments was performed on soft and hard lead-zirconate-titanate (PZT) structures to determine the effectiveness of ultrasonic measurements as a nondestructive method of evaluating poling quality and uniformity. The study revealed that acoustic velocity correlates well with the degree of poling of PZT structures, as predicted by elastic theory. Additionally, time-of-flight (TOF) imaging was shown to be an ideal tool for viewing the spatial distribution of poled material and of material affected by the electric field beyond the edge of electroded regions. Finally, the effectiveness of ultrasonic methods for flaw detection and evaluation of PZT/stainless steel bonds was also demonstrated.
Date: March 14, 2000
Creator: Jamieson, E.E.
Partner: UNT Libraries Government Documents Department

Anode Materials for Rechargeable Li-Ion Batteries

Description: This is the annual progress report for the Grant DE-FG03-00ER15035. This research is on materials for anodes and cathodes in electrochemical cells. The work is a mix of electrochemical measurements and analysis of the materials by transmission electron microscopy and x-ray diffractometry. Our materials studies on electrode materials divide into electronic studies of the valence at and around Li atoms, and the crystal structures of these materials. We are addressing the basic questions of how these change with Li concentration, and what long-term changes take place during charge/discharge cycling of the materials.
Date: January 12, 2001
Creator: Fultz, B.
Partner: UNT Libraries Government Documents Department

LOW-TEMPERATURE, ANODE-SUPPORTED HIGH POWER DENSITY SOLID OXIDE FUEL CELLS WITH NANOSTRUCTURED ELECTRODES

Description: This report contains the following three parts. (1) An investigation into the use of direct liquid hydrocarbon fuels in single cell tests. (2) An analysis of residual stresses in anode-supported solid oxide fuel cells. (3) A manuscript on the synthesis of nanosize ceramic (electrode and electrolyte) powders. Nanosize YSZ powder was prepared by a unique approach, in which yttria-doped BaZrO{sub 3} or yttria-doped Na{sub 2}ZrO{sub 3} precursors were first synthesized by a solid state reaction. Then, then the unwanted species, BaO or Na{sub 2}O, was leached away by washing the precursors in a dilute HNO{sub 3} solution or in water. This led to the formation of very fine, nanosize yttria-stabilized zirconia (YSZ). The particle size of the as-synthesized YSZ powders was a few nanometers and increased to tens of nanometers after thermal treatment at a temperature as high as 1000 C. The as-synthesized as well as heat-treated YSZ powder was of cubic crystal structure.
Date: April 7, 2000
Creator: Virkar, Prof. Anil V.
Partner: UNT Libraries Government Documents Department

POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING

Description: Work continued during the past quarter to improve the performance of the POC-scale unit. For the charging system, a more robust ''turbocharger'' has been fabricated and installed. All of the internal components of the charger have been constructed from the same material (i.e., Plexiglas) to prevent particles from contacting surfaces with different work functions. For the electrode system, a new set of vinyl-coated electrodes have been constructed and tested. The coated electrodes (i) allow higher field strengths to be tested without of risk of arcing and (ii) minimize the likelihood of charge reversal caused by particles colliding with the conducting surfaces of the uncoated electrodes. Tests are underway to evaluate these modifications. Several different coal samples were collected for testing during this reporting period. These samples included (i) a ''reject'' material that was collected from the pyrite trap of a pulverizer at a coal-fired power plant, (ii) an ''intermediate'' product that was selectively withdrawn from the grinding chamber of a pulverizer at a power plant, and (iii) a run-of-mine feed coal from an operating coal preparation plant. Tests were conducted with these samples to investigate the effects of several key parameters (e.g., particle size, charger type, sample history, electrode coatings, etc.) on the performance of the bench-scale separator.
Date: October 1, 2000
Creator: Yoon, R.-H.; Luttrell, G.H.; Luvsansambuu, B. & Walters, A.D.
Partner: UNT Libraries Government Documents Department

Determination of Parts-Per-Million Cesium in Simulated Nuclear Waste with the Cesium-Selective Electrode

Description: Because the molybdophosphate electrode was not sufficiently sensitive, and the reliability of the ''liquid state'' electrode for routine analysis was uncertain, a cesium-selective electrode of the proven liquid membrane type was developed. This paper describes preparation and testing of a liquid membrane electrode that contains cesium tetraphenylboron dissolved in 4-ethylnitrobenzene.
Date: October 23, 2001
Creator: Baumann, E. W.
Partner: UNT Libraries Government Documents Department

LOW-TEMPERATURE, ANODE-SUPPORTED HIGH POWER DENSITY SOLID OXIDE FUEL CELLS WITH NANOSTRUCTURED ELECTRODES

Description: Nanosize yttria-stabilized zirconia (YSZ) was synthesized by a unique approach based on molecular decomposition. In this approach, yttria-doped BaZrO{sub 3} (Y-BaZrO{sub 3}) or yttria-doped Na{sub 2}ZrO{sub 3} (Y-Na{sub 2}ZrO{sub 3}) precursors were first synthesized from BaCO{sub 3}, ZrO{sub 2}, Y2O{sub 3} or BaCO{sub 3} and commercial YSZ for Y-BaZrO{sub 3}, and from Na{sub 2}CO{sub 3} and YSZ for Y-Na{sub 2}ZrO{sub 3}, by a conventional solid state reaction method. Then, the precursors were boiled to leach away the unwanted species, BaO or Na{sub 2}O, either in a dilute HNO{sub 3} solution in water in the case of Y-BaZrO{sub 3}, or in de-ionized water in the case of Y-Na{sub 2}ZrO{sub 3}. During boiling in HNO{sub 3} or water, the insoluble residue of Zr-Y-O composition formed fine, nanosize YSZ particles. X-ray diffraction (XRD) and specific surface area measurements on the as-synthesized powders confirmed the formation of nanosize YSZ. A subsequent heating in air led to particle growth. However, for a treatment at a temperature as high as 1000 C, the particle size was well in the nanosize range. XRD showed that the as-synthesized YSZ powders, as well as those heated up to 1000 C, the maximum temperature the powders were heated to after leaching, are of cubic structure.
Date: April 7, 2000
Creator: Virkar, Prof. Anil V.
Partner: UNT Libraries Government Documents Department

OPTICALLY BASED CHARGE INJECTION SYSTEM FOR IONIZATION DETECTORS.

Description: An optically coupled charge injection system for ionization based radiation detectors which allows a test charge to be injected without the creation of ground loops has been developed. An ionization like signal from an external source is brought into the detector through an optical fiber and injected into the electrodes by means of a photodiode. As an application example, crosstalk measurements on a liquid Argon electromagnetic calorimeter readout electrodes were performed.
Date: September 11, 2001
Creator: CHEN,H.; CITTERIO,M.; LANNI,F.; LEITE,M.A.L.; RADEKA,V.; RESCIA,S. et al.
Partner: UNT Libraries Government Documents Department