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Sample records for cathode gas humidification

  1. Effect of cathode gas humidification on performance and durability of Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Hagen, Anke; Liu, Yi-Lin

    2010-01-01

    The effect of cathode inlet gas humidification was studied on single anode supported Solid Oxide Fuel Cells (SOFC's). The studied cells were Risø 2 G and 2.5 G. The former consists of a LSM:YSZ composite cathode, while the latter consists of a LSCF:CGO composite cathode on a CGO protection layer......-SEM analysis showed clear changes at and around the cathode/electrolyte contact area. In contrast to Risø 2 G cells, a very high tolerance towards humidification of cathode gas air was observed for Risø 2.5 G cells with no detectable effect of humidification even when the humidification was as high as 12.8 mol%...... respectively. A clear effect of humidification was observed for 2 G cells with a fast transient upon humidification followed by an ongoing long term passivation/degradation during humidification. Removal of humidification resulted in a partial regain of the cell voltage prior to humidification...

  2. Water vapor exchange system using a hydrophilic microporous layer coated gas diffusion layer to enhance performance of polymer electrolyte fuel cells without cathode humidification

    Science.gov (United States)

    Kitahara, Tatsumi; Nakajima, Hironori; Morishita, Masashi

    2012-09-01

    Polymer electrolyte fuel cells (PEFCs) generally have external humidifiers to supply humidified hydrogen and oxidant gases, which prevents dehydration of the membrane. If a PEFC could be operated without humidification, then external humidifiers could be removed, which would result in a simplified PEFC system with increased total efficiency and reduced cost. A water vapor exchange system installed in the PEFC was developed to enhance the performance without cathode humidification. A gas diffusion layer (GDL) coated with a hydrophobic microporous layer (MPL) was used at the active reaction area. A GDL coated with a hydrophilic MPL consisting of polyvinyl alcohol (PVA) and carbon black was used at the cathode water vapor exchange area to promote water transport from the cathode outlet wet gas to the anode inlet dry gas. This is effective for reducing the IR overpotential, which enhances the PEFC performance. Appropriate enhancement of hydrophilicity by increasing the PVA content in the MPL to 20 mass% is effective to increase water transport from the cathode to anode. At the anode water exchange area, a GDL without the hydrophilic MPL is effective to promote water transport from the water exchange area to the active reaction area, which enhances the PEFC performance.

  3. Influence of humidification on deterioration of gas diffusivity in catalyst layer on polymer electrolyte fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Hiramitsu, Y.; Sato, H.; Kobayashi, K.; Hori, M. [Fuel Cell Research Center, Daido University, 10-3 Takiharu-cho, Minami-ku, Nagoya 457-8530 (Japan); Hosomi, H.; Aoki, Y.; Harada, T.; Sakiyama, Y.; Nakagawa, Y. [Toray Research Center Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan)

    2010-01-15

    The effect of water on polymer electrolyte fuel cell degradation was examined with humidity as a parameter. Polymer electrolyte fuel cells were subjected to long-term operation of 10 000 h to examine the relation between decline in cell voltage and degradation of the catalyst layers or gas diffusion layers. The diffusion overpotential increased during long-term operation at relatively high humidification of 81% RH, but only in the catalyst layer and not in the gas diffusion layer. At low humidification of 52% RH, the increase in diffusion overpotential was small, indicating that the increase was more likely to occur under high humidification. Post-analysis of the catalyst layer revealed that the membrane electrode assembly had increased diffusion overpotential during operation under high humidification, as a result of the sharp decline in porosity. The increase of diffusion overpotential in the catalyst layer was also investigated by the observation of the degradation due to the oxidation of the Pt-carbon supports. However, it was found that the oxidation of carbon support which had increased diffusion overpotential was small. (author)

  4. Performance Change of Hydrogen Fueled Polymer Electrolyte Fuel Cell Internally Humidified at the Cathode by Gas Flow Pattern

    Science.gov (United States)

    Kano, Akio; Tanaka, Kazuhisa; Aoki, Tsutomu; Ogami, Yasuji; Saso, Hidetoshi; Abe, Satoshi; Hariyama, Suguru; Nishikawa, Hisao

    With high hydrogen utilization operation, a minor imbalance in the distributed flow of the stack causes a shortage of hydrogen gas. In order to achieve high hydrogen utilization operation, we investigated the flow pattern for cells internally humidified at the cathode side. We fabricated both counter flow and co flow type cells for humidification of the cells inside the cathode and carried out electricity generation tests on single cells and cell stacks. Also we measured the distribution of relative humidity at the anode electrode for counter flow and co flow humidification of the cell inside the cathode. From these test results we concluded that the counter flow method is superior as a humidification cell inside a cathode when using the stack division method.

  5. [Noise in intensive care units. Noise reduction by modification of gas humidification].

    Science.gov (United States)

    Berg, P W; Stuttmann, R; Doehn, M

    1997-10-01

    Today, noise pollution is an evident and ubiquitous problem even in intensive care units. Noise can disturb the physiological and psychological balance in patients and staff. Especially intubated patients and those breathing spontaneously through a T-piece are exposed to the noise emitted by the nebuliser used to humidity the respiratory gas. This may make patients feel uncomfortable. To reduce noise pollution in the ICU a modified T-piece has been developed and investigated. In order to heat and humidity the respiratory gas a Conchaterm III unit (Kendall company) and a thermo flow cylinder (De Vilbiss company) is necessary. While respiratory gas is flowing, water is sucked out of the heated thermoflow cylinder and nebulised according to the Venturi-Bernoulli principle. To adjust the oxygen concentration of the respiratory gas a plastic ring must be turned to either close (98% oxygen) or open a valve allowing room air to mix (40% oxygen). Noise pollution of the unit varies with admixture of room air. With a new device--a special oxygen-air mixing chamber--the oxygen concentration of the respiratory gas can be adjusted outside the thermoflow cylinder, hardly producing any noise pollution. Therefore the principle of nebulisation could be changed to humidification. A thermoflow cylinder without the nebulisation unit allows the respiratory gas to flow through the thermoflow cylinder over heated and evaporating water, hardly causing any noise pollution. In both types of T-pieces the temperature of the respiratory gas is controlled and corrected by the Conchaterm unit. As the result of these modifications, noise pollution has been reduced from 70 dB(A) to 55 dB(A). In the modified T-piece, the quality of humidification has been evaluated with a fresh gas flow of 22 l/min and at a gas temperature of 37 degrees C, not only collecting condensed water but also lost water. The modified T-piece allows a physiological humidification of the respiratory gas. The modified T

  6. The ejector flowmeter as air/oxygen mixing device. An apparatus providing gas mixtures with adjustable oxygen content for high-flow humidification systems.

    Science.gov (United States)

    Christensen, K N; Waaben, J; Jørgensen, S

    1980-04-01

    The ejector flowmeter is constructed for continuous removal of excess gas from anaesthetic circuits. This instrument can be used as an air/oxygen mixing device for high-flow humidification systems in wards where compressed air is not available. Pure oxygen is used as driving gas through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of air to the flowmeter, FIO2 and total outflow.

  7. Airfoil lance apparatus for homogeneous humidification and sorbent dispersion in a gas stream

    Science.gov (United States)

    Myers, Robert B.; Yagiela, Anthony S.

    1990-12-25

    An apparatus for spraying an atomized mixture into a gas stream comprises a stream line airfoil member having a large radius leading edge and a small radius trailing edge. A nozzle assembly pierces the trailing edge of the airfoil member and is concentrically surrounded by a nacelle which directs shielding gas from the interior of the airfoil member around the nozzle assembly. Flowable medium to be atomized and atomizing gas for atomizing the medium are supplied in concentric conduits to the nozzle. A plurality of nozzles each surrounded by a nacelle are spaced along the trailing edge of the airfoil member.

  8. Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

    Directory of Open Access Journals (Sweden)

    Claudia Hernández-Jiménez

    Full Text Available The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5, mechanical ventilation with dry oxygen dispensation, and Group II (n = 5, mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77. This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05. Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02. Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

  9. Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

    Science.gov (United States)

    Hernández-Jiménez, Claudia; García-Torrentera, Rogelio; Olmos-Zúñiga, J Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel O; Baltazares-Lipp, Matilde; Gutiérrez-González, Luis H

    2014-01-01

    The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5), mechanical ventilation with dry oxygen dispensation, and Group II (n = 5), mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77). This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05). Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02). Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

  10. Fuel cell membrane humidification

    Science.gov (United States)

    Wilson, Mahlon S.

    1999-01-01

    A polymer electrolyte membrane fuel cell assembly has an anode side and a cathode side separated by the membrane and generating electrical current by electrochemical reactions between a fuel gas and an oxidant. The anode side comprises a hydrophobic gas diffusion backing contacting one side of the membrane and having hydrophilic areas therein for providing liquid water directly to the one side of the membrane through the hydrophilic areas of the gas diffusion backing. In a preferred embodiment, the hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the backing. Liquid water is distributed over the gas diffusion backing in distribution channels that are separate from the fuel distribution channels.

  11. Humidification on Ventilated Patients: Heated Humidifications or Heat and Moisture Exchangers?

    Science.gov (United States)

    Cerpa, F; Cáceres, D; Romero-Dapueto, C; Giugliano-Jaramillo, C; Pérez, R; Budini, H; Hidalgo, V; Gutiérrez, T; Molina, J; Keymer, J

    2015-01-01

    The normal physiology of conditioning of inspired gases is altered when the patient requires an artificial airway access and an invasive mechanical ventilation (IMV). The endotracheal tube (ETT) removes the natural mechanisms of filtration, humidification and warming of inspired air. Despite the noninvasive ventilation (NIMV) in the upper airways, humidification of inspired gas may not be optimal mainly due to the high flow that is being created by the leakage compensation, among other aspects. Any moisture and heating deficit is compensated by the large airways of the tracheobronchial tree, these are poorly suited for this task, which alters mucociliary function, quality of secretions, and homeostasis gas exchange system. To avoid the occurrence of these events, external devices that provide humidification, heating and filtration have been developed, with different degrees of evidence that support their use.

  12. Catalyst Degradation Under Potential Cycling as an Accelerated Stress Test for PBI-Based High-Temperature PEM Fuel Cells - Effect of Humidification

    DEFF Research Database (Denmark)

    Søndergaard, Tonny; Cleemann, Lars Nilausen; Zhong, Lijie

    2017-01-01

    In the present work, high-temperature polymer electrolyte membrane fuel cells were subjected to accelerated stress tests of 30,000 potential cycles between 0.6 and 1.0 V at 160 textdegreeC (133 h cycling time). The effect that humidity has on the catalyst durability was studied by testing either...... with or without humidification of the nitrogen that was used as cathode gas during cycling segments. Pronounced degradation was seen from the polarization curves in both cases, though permanent only in the humidified case. In the unhumidified case, the performance loss was more or less recoverable following 24 h...... humidification of this region. Catalyst degradation due to platinum dissolution, transport of its ions, and eventual recrystallization is reduced when this portion of the acid dries out. Consequently, catalyst particles are only mildly affected by the potential cycling in the unhumidified case....

  13. Nitrogen-doped carbonaceous catalysts for gas-diffusion cathodes for alkaline aluminum-air batteries

    Science.gov (United States)

    Davydova, E. S.; Atamanyuk, I. N.; Ilyukhin, A. S.; Shkolnikov, E. I.; Zhuk, A. Z.

    2016-02-01

    Cobalt tetramethoxyphenyl porphyrin and polyacrylonitrile - based catalysts for oxygen reduction reaction were synthesized and characterized by means of SEM, TEM, XPS, BET, limited evaporation method, rotating disc and rotating ring-disc electrode methods. Half-cell and Al-air cell tests were carried out to determine the characteristics of gas-diffusion cathodes. Effect of active layer thickness and its composition on the characteristics of the gas-diffusion cathodes was investigated. Power density of 300 mW cm-2 was achieved for alkaline Al-air cell with an air-breathing polyacrylonitrile-based cathode.

  14. Humidification in intensive care

    African Journals Online (AJOL)

    Nicky

    2005-07-26

    Jul 26, 2005 ... The water vapour content of a gas can be expressed as a pressure according to Dalton's law of partial pressures (kPa, mmHg). At 37°C the SVP of water is. 47 mmHg. Energy is required for water to move from the liquid phase to gas phase. This energy is called the latent heat of vaporisation and results in ...

  15. The influence of humidification and temperature differences between inlet gases on water transport through the membrane of a proton exchange membrane fuel cell

    Science.gov (United States)

    Huang, Kuan-Jen; Hwang, Sheng-Jye; Lai, Wei-Hsiang

    2015-06-01

    This paper discusses the effects of humidification and temperature differences of the anode and cathode on water transport in a proton exchange membrane fuel cell. Heaters are used to cause a difference in gas temperature between two electrodes before the gases enter the fuel cell. The results show that when the temperature of the cathode is higher than that of the anode, the electro-osmotic drag is suppressed. In contrast, when the temperature of the anode is higher than that of cathode, it is enhanced. These effects are more significant when the temperature difference between the anode and cathode is greater. The same trends are seen with back diffusion. Three cases are tested, and the results show that the suppression due to the temperature difference occurs even when the relative humidity is low at the hotter side. The water transport tendencies of electro-osmotic drag and back diffusion in different situations can be expressed as dominant percentages calculated by the water masses collected at the anode and cathode. The suppression effect due to the temperature difference is relatively insignificant with regard to back diffusion compared to electro-osmosis, so water tends to accumulate on the anode rather than the cathode side.

  16. Humidification in intensive care | Williams | Southern African Journal ...

    African Journals Online (AJOL)

    Humidification of inspired gases is an essential part of modern intensive care practice, but there is wide international variation in the application of humidification devices.1 This review aims to briefly cover the reasons why humidification is important and the main methods of humidification used, outlining their different ...

  17. A Comparison of Fick and Maxwell-Stefan Diffusion Formulations in PEMFC Cathode Gas Diffusion Layers

    OpenAIRE

    Lindstrom, Michael; Wetton, Brian

    2013-01-01

    This paper explores the mathematical formulations of Fick and Maxwell-Stefan diffusion in the context of polymer electrolyte membrane fuel cell cathode gas diffusion layers. Formulations of diffusion combined with mass-averaged Darcy flow are considered for three component gases. Fick formulations can be considered as approximations of Maxwell-Stefan in a certain sense. For this application, the formulations can be compared computationally in a simple, one dimensional setting. We observe that...

  18. Inadequate humidification of respiratory gases during mechanical ventilation of the newborn.

    OpenAIRE

    Tarnow-Mordi, W O; Sutton, P; Wilkinson, A R

    1986-01-01

    Proximal airway humidity was measured during mechanical ventilation in 14 infants using an electronic hygrometer. Values below recommended minimum humidity of adult inspired gas were recorded on 251 of 396 occasions. Inadequate humidification, largely due to inadequate proximal airway temperature, is commoner than recognised in infants receiving mechanical ventilation.

  19. Humidification performance of heat and moisture exchangers for pediatric use.

    Science.gov (United States)

    Chikata, Yusuke; Sumida, Chihiro; Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

    2012-01-01

    Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH(2)O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH(2)O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

  20. Humidification Performance of Heat and Moisture Exchangers for Pediatric Use

    Directory of Open Access Journals (Sweden)

    Yusuke Chikata

    2012-01-01

    Full Text Available Background. While heat and moisture exchangers (HMEs have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small and 5.1 L/min (large when pressure was 10 cmH2O. We measured absolute humidity (AH at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L, decreasing further (19.7 to 27.3 mg/L with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

  1. Design and control of the oxygen partial pressure of UO{sub 2} in TGA using the humidification system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Knight, T.W., E-mail: knighttw@cec.sc.edu; Roberts, E.

    2015-10-15

    Highlights: • We focus on measurement of oxygen partial pressure and change of O/M ratio under specific conditions produced by the humidification system. • This shows that the humidification system is stable, accurate, and reliable enough to be used for experiments of the oxygen partial pressure measurement for the oxide fuels. • The humidification system has benefits of easy control and flexibility for producing various oxygen partial pressures with fixed hydrogen gas flow rate. - Abstract: The oxygen to uranium (O/U) ratio of UO{sub 2±x} is determined by the oxygen content of the sample and is affected by oxygen partial pressure (pO{sub 2}) of the surrounding gas. Oxygen partial pressure is controllable by several methods. A common method to produce different oxygen partial pressures is the use of equilibria of different reaction gases. There are two common methods: H{sub 2}O/H{sub 2} reaction and CO{sub 2}/CO reaction. In this work, H{sub 2}O/H{sub 2} reaction using a humidifier was employed and investigated to ensure that this humidification system for oxygen partial pressure is stable and accurate for use in Thermogravimetric Analyzer (TGA) experiments with UO{sub 2}. This approach has the further advantage of flexibility to make a wide range of oxygen partial pressure with fixed hydrogen gas flow rate only by varying temperature of water in the humidifier. The whole system for experiments was constructed and includes the humidification system, TGA, oxygen analyzer, and gas flow controller. Uranium dioxide (UO{sub 2}) samples were used for experiments and oxygen partial pressure was measured at the equilibrium state of stoichiometric UO{sub 2.0}. Oxygen partial pressures produced by humidification (wet gas) system were compared to the approach using mixed dry gases (without humidification system) to demonstrate that the humidification system provides for more stable and accurate oxygen partial pressure control. This work provides the design, method, and

  2. Airway Humidification During High-Frequency Percussive Ventilation

    Science.gov (United States)

    2009-03-01

    Association for Respi- ratory Care (AARC) recommendations for the minimum acceptable heating and humidification during mechanical ventilation ( 30°C...Care. AARC clinical practice guideline: humidification during mechanical ventilation . Respir Care 1992;37(8):887-890. 3. Branson RD. The effects of...Airway Humidification During High-Frequency Percussive Ventilation Patrick F Allan MD, Michael J Hollingsworth CRT, Gordon C Maniere CRT, Anthony K

  3. Evaluation of Cathode Gas Composition and Temperature Influences on Alkaline Anion Exchange Membrane Fuel Cell (AAEMFC Performance

    Directory of Open Access Journals (Sweden)

    Topal Leyla

    2014-02-01

    Full Text Available The effects of different temperatures (55, 65, 75 and 85 °C and cathode gas compositions (O2, synthetic air, air and 90% synthetic air+10% CO2 on alkaline anion exchange membrane fuel cell (AAEMFC were evaluated. Membrane electrode assemblies (MEA were fabricated using commercial anion exchange membrane (AEM in OH- form and Pt catalyst. Polarization curves and voltage responses during constant current were performed in order to describe the influences of temperature and gas composition on the AAEMFC performance. The experimental results showed that the fuel cell performance increases with elevating temperatures for all applied gas compositions. Highest power density of 34.7 mW cm-2 was achieved for pure O2 as cathode feed. A decrease to 20.3 mW cm-2 was observed when cathode gas composition was changed to synthetic air due to reduction of the O2 partial pressure. The presence of CO2 in atmospheric air applied to the cathode stream caused a further drop of the maximum power density to 15.2 mW cm-2 driven by neutralization of OH- ions with CO2.

  4. Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure.

    Science.gov (United States)

    Nikolaev, A G; Savkin, K P; Yushkov, G Yu; Oks, E M

    2014-02-01

    The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed.

  5. Radio-based remote monitoring of cathodic protection of natural gas pipelines; Radiobaserad fjaerroevervakning av katodiskt skydd av naturgasledningar

    Energy Technology Data Exchange (ETDEWEB)

    Camitz, G. [Swedish Corrosion Inst., Stockholm (Sweden); Edwall, H-E. [Sydgas AB (Sweden); Marbe, Aa. [Sydkraft Konsult AB, Malmoe (Sweden)

    1996-11-01

    The high pressure pipeline systems for transmission of natural gas in the southernmost part of Sweden have a total length of 380 km. The steel pipes are extremely well insulated towards earth by a 3-4 mm thick polyethylene coating. The pipelines are also protected by a cathodic protection system to prevent corrosion attacks at coating holidays. The high electrical insulating ability of the pipe coating involves, however, a higher sensitivity to electrical interference from foreign direct current and alternating current sources. To improve the monitoring of the cathodic protection of the pipelines, a radio based remote monitoring system has been installed at a large number of representative positions in the pipeline network. In every monitoring position the cathodic protection potential of the pipeline is recorded both as an ON-potential and as an IR-free potential. In certain places, the pipeline`s alternating voltage with respect to neutral earth is also recorded. Data are recorded every minute and are sent continuously via a radio signal to a central computer for processing. Each morning, the previous day`s measurements are printed out automatically in the form of diagrams, at the office of the gas company`s cathodic protection department, for examination. Five years` experience shows that the remote monitoring constitutes an efficient tool for the early discovery of malfunctions in the cathodic protection system or of other detrimental influences on the pipelines. In this report the design of the remote monitoring system is described together with a number of serious incidents due to faults in the cathodic protection system, which were discovered at an early stage with the help of the monitoring system. Time and cost savings associated with the remote monitoring are also discussed. 3 refs, 8 figs, 2 tabs

  6. Advanced structure of cathode for gas discharge lamp of super high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kruglenya, P.A.; Maslennikov, O.Y

    2003-06-15

    This paper presents a new cathode structure for short length arc-plasma circular lamp DRKs2-1500 filled with mercury-xenon of super high pressure. A conventional cathode of thoriated tungsten was replaced by a new structure of tungsten-barium. This cathode has emitting surface of cavity form which enables to reduce active material evaporation from the surface and to increase emission stability. It was found that light parameters of the lamp depend on the geometry of its electrodes. Fusing and evaporation of the cathode material result in a cathode size change and lead to changes of arc-plasma parameters, blackening of the lamp envelope and decreasing luminous flux intensity. The tests showed that the lamp service life with the new cathode grows as much as 2-3 times. Optimization of the cathode cavity geometric size is expected to enlarge the lamp service life up to 3000-5000 h (guaranteed service life of a lamp with usual structure of cathode is 500 h)

  7. Fast turn-on characteristics of tungsten-based dispenser cathodes following gas exposures

    Science.gov (United States)

    Marrian, C. R. K.; Haas, G. A.; Shih, A.

    The problems associated with the reactivation following shelf storage of different types of tungsten-based dispenser cathodes have been investigated. Reactivation times were found to be severely limited by repoisoning processes, which have been isolated and identified. Data are presented, indicating the finite times (in the absence of repoisoning), which are required to reactivate the cathodes following exposure to various gases. Of the gases studied, exposure to oxygen and water vapour caused the slowest reactivations. Water vapour was the component of the vacuum system ambient responsible for the poisoning caused by exposure to the ambient. Following exposure to each of the gases studied, the "M" type cathode reactivated slower than the "B" type cathode. The results have shown that both the choice of cathode and the design of the microwave tube are important if a fast turn-on following shelf storage is to be achieved.

  8. Pore former induced porosity in LSM/CGO cathodes for electrochemical cells for flue gas purification

    DEFF Research Database (Denmark)

    Skovgaard, M.; Andersen, Kjeld Bøhm; Kammer Hansen, Kent

    2012-01-01

    In this study the effect of the characteristics of polymethyl methacrylate (PMMA) pore formers on the porosity, pore size distribution and the air flow through the prepared lanthanum strontium manganate/gadolinium-doped cerium oxide (LSM/CGO) cathodes was investigated. Porous cathodes were obtained...... and the highest porosity measured was 46.4% with an average pore diameter of 0.98 μm. The air flow through this cathode was measured to 5.8 ml/(min mm2). Also the effect of exposure time to the solvent was tested for the most promising PMMA pore former and it was found that the average pore diameter decreases...... as a result of elongated exposure. Also prolong milling of the LSM powder was found to decrease the porosity of the final cathode and milling time should be highly controlled in order to obtain as porous cathodes as possible....

  9. Enhanced hydroxyl radical generation in the combined ozonation and electrolysis process using carbon nanotubes containing gas diffusion cathode.

    Science.gov (United States)

    Wu, Donghai; Lu, Guanghua; Zhang, Ran; Lin, Qiuhong; Yan, Zhenhua; Liu, Jianchao; Li, Yi

    2015-10-01

    Combination of ozone together with electrolysis (ozone-electrolysis) is a promising wastewater treatment technology. This work investigated the potential use of carbon nanotube (CNT)-based gas diffusion cathode (GDC) for ozone-electrolysis process employing hydroxyl radicals (·OH) production as an indicator. Compared with conventional active carbon (AC)-polytetrafluoroethylene (PTFE) and carbon black (CB)-PTFE cathodes, the production of ·OH in the coupled process was improved using CNTs-PTFE GDC. Appropriate addition of acetylene black (AB) and pore-forming agent Na2SO4 could enhance the efficiency of CNTs-PTFE GDC. The optimum GDC composition was obtained by response surface methodology (RSM) analysis and was determined as CNTs 31.2 wt%, PTFE 60.6 wt%, AB 3.5 wt%, and Na2SO4 4.7 wt%. Moreover, the optimized CNT-based GDC exhibited much more effective than traditional Ti and graphite cathodes in Acid Orange 7 (AO7) mineralization and possessed the desirable stability without performance decay after ten times reaction. The comparison tests revealed that peroxone reaction was the main pathway of ·OH production in the present system, and cathodic reduction of ozone could significantly promote ·OH generation. These results suggested that application of CNT-based GDC offers considerable advantages in ozone-electrolysis of organic wastewater.

  10. [Effect of airway humidification on lung injury induced by mechanical ventilation].

    Science.gov (United States)

    Song, Junjie; Jiang, Min; Qi, Guiyan; Xie, Yuying; Wang, Huaiquan; Tian, Yonggang; Qu, Jingdong; Zhang, Xiaoming; Li, Haibo

    2014-12-01

    To explore the effect of airway humidification on lung injury as a result of mechanical ventilation with different tidal volume (VT). Twenty-four male Japanese white rabbits were randomly divided into four groups: low VT with airway humidification group, high VT with airway humidification group, low VT and high VT group without humidification, with 6 rabbits in each group. Mechanical ventilation was started after intubation and lasted for 6 hours. Low VT denoted 8 mL/kg, while high VT was 16 mL/kg, fraction of inspired oxygen (FiO₂) denoted 0.40, positive end-expiratory pressure (PEEP) was 0. Temperature at Y piece of circuit in airway humidification groups was monitored and controlled at 40 centigrade. Arterial blood gas analysis, including pH value, arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂), lung mechanics indexes, including peak airway pressure (P(peak)) and airway resistance (Raw), and lung compliance was measured at 0, 2, 4, 6 hours of mechanical ventilation. The levels of tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) in plasma and bronchoalveolar lavage fluid (BALF) were determined by enzyme linked immunosorbent assay (ELISA). The animals were sacrificed at the end of mechanical ventilation. The wet to dry (W/D) ratio of lung tissues was calculated. Histopathologic changes in the lung tissueies were observed with microscope, and lung injury score was calculated. Scanning and transmission electron microscopies were used to examine the integrity of the airway cilia and the tracheal epithelium. Compared with low V(T) group, pH value in high V(T) group was significantly increased, PaCO₂was significantly lowered, and no difference in PaO₂was found. P(peak), Raw, and lung compliance were significantly increased during mechanical ventilation. There were no significant differences in blood gas analysis and lung mechanics indexes between low V(T) with airway humidification group and low V

  11. High-performance cathode elements for gas-discharge light sources

    Directory of Open Access Journals (Sweden)

    Sevastyanov V. V.

    2009-02-01

    Full Text Available Application of cathode elements of the arc-discharge activator made on the basis of developed material — alloy of iridium and rare-earth metals (of cerium group — has been suggested. The working samples of arc lamps have been produced and tested. The location of metal-alloy cathode has been optimized. The tests demonstrated, that after 4500 hours of work the lighting-up and glowing parameters of such lamps remained stable.

  12. Study of the prebreakdown stage of a gas discharge in a diode with point cathode by laser probing

    Science.gov (United States)

    Parkevich, E. V.; Tkachenko, S. I.; Agafonov, A. V.; Mingaleev, A. R.; Romanova, V. M.; Shelkovenko, T. A.; Pikuz, S. A.

    2017-04-01

    The prebreakdown stage of a gas discharge in a diode with strongly overloaded cathode is studied by laser methods (by simultaneous use of multiframe interferometry and shadow and schlieren photographing) at atmospheric pressure. The spatial resolution of the methods is about 20 μm. A probing pulse of a laser (LS-2151 Nd: YAG laser with a half amplitude duration of 70 ps and a pulse energy of up to 40 mJ) is synchronized with a voltage pulse with accuracy of about 1 ns. High field strength at the cathode is achieved due to the use of thin individual metal tips on the electrodes. It is shown that the initial stage of breakdown of a discharge gap is accompanied by the emergence of a dense plasma cloud at the end of a tip with electron density of about 5 × 1019 cm-3 with a size of tens of microns, as well as by a sharp increase in the total current through the diode. After the emergence of a dense plasma cloud at the end of a cathode tip, a similar cloud is formed on the surface of the anode; sometime later, these clouds join together and form a tubular current channel. The dynamics of the breakdown, as well as the parameters of the plasma are studied by the abovementioned techniques in three independent optical channels.

  13. Design of carbon nanotube-based gas-diffusion cathode for O{sub 2} reduction by multicopper oxidases

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Carolin; Adkins, Emily R.; Atanassov, Plamen [University of New Mexico, Center for Emerging Energy Technologies, Albuquerque, NM (United States); Ramasamy, Ramaraja P. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States); Nano-Electrochemistry Laboratory, Faculty of Engineering, University of Georgia, Athens, GA (United States); Luckarift, Heather R.; Johnson, Glenn R. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States)

    2012-01-15

    Multicopper oxidases, such as laccase or bilirubin oxidase, are known to reduce molecular oxygen at very high redox potentials, which makes them attractive biocatalysts for enzymatic cathodes in biological fuel cells. By designing an enzymatic gas-diffusion electrode, molecular oxygen can be supplied through the gaseous phase, avoiding solubility and diffusion limitations typically associated with liquid electrolytes. In doing so, the current density of enzymatic cathodes can theoretically be enhanced. This publication presents a material study of carbon/Teflon composites that aim to optimize the functionality of the gas-diffusion and catalytic layers for application in enzymatic systems. The modification of the catalytic layer with multiwalled carbon nanotubes, for example, creates the basis for stronger {pi}-{pi} stacking interactions through tethered enzymatic linkers, such as pyrenes or perylene derivates. Cyclic voltammograms show the effective direct electron contact of laccase with carbon nanotube-modified electrodes via tethered crosslinking molecules as a model system. The polarization behavior of laccase-modified gas-diffusion electrodes reveals open-circuit potentials of +550 mV (versus Ag/AgCl) and current densities approaching 0.5 mA cm{sup 2} (at zero potential) in air-breathing mode. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Thermodynamic Evaluation of LSCF Cathode Stability and Tolerance towards Gas Impurities

    DEFF Research Database (Denmark)

    Zhang, Weiwei; Chen, Ming; Hendriksen, Peter Vang

    2014-01-01

    Strontium and iron co-doped lanthanum cobaltites (La1-xSrxCo1-yFeyO3-δ, LSCF) show good oxygen ion and electronic conductivity and fast oxygen surface exchange kinetics at temperatures between 600 and 800 °C, and is considered today one of the most promising class of cathode materials...... for intermediate-temperature solid oxide fuel cells. Despite its technological importance, the phase stability of the LSCF perovskite has not yet been fully mapped out and may be critical for the use of the materials during long-term operation. For cells with LSCF or LSCF/CGO (CGO: gadolinia doped ceria) cathodes...

  15. Transfer of charges and substances in a gas-discharge plasma from the liquid electrolyte cathode containing salts of alkali metal

    Science.gov (United States)

    Tazmeev, Kh K.; Timerkaev, B. A.; Tazmeev, G. K.

    2017-11-01

    A gas discharge in the air between the flowing liquid cathode and a solid anode was studied experimentally. Aqueous solution of sodium chloride was used as the liquid cathode electrolyte. Mass loss due to evaporating and sputtering was compensated by adding distilled water in a continuous mode. It was found that the specific electric conductivity of the aqueous solution is almost unchanged. The regularities of changes in the composition of an anionic solution were discovered.

  16. Effect of Gas Composition on the Performance of Cathode Strip Chambers for the CMS Endcap Muon System

    CERN Document Server

    Anderson, C; Korenblit, S; Korytov, Andrey; Mitselmakher, Guenakh

    2004-01-01

    The composition of the gas inside the cathode strip chambers (CSCs) defines many important performance parameters, including the gas gain and operational voltage range. Differences in these parameters were examined under variations in concentration of argon, carbon dioxide, and carbon tetrafluoride around the baseline mixture of Ar+CO2+CF4 = 40+50+10. The gas gain was found to be dependent primarily on the Ar concentration and nearly insensitive of the CF4/CO2 relative concentrations. The operational voltage range of ~370V had only a weak dependence on Ar concentration in the range of 40%-60% (-30 V for +20% change) at fixed amount of CF4, but showed about 3 times stronger dependence on the concentration of CF4 (+90 V for the concentration change from 0% to 20%) at fixed amount of Ar. We discuss 2 alternative gas mixtures Ar+CO2+CF4 = 60+30+10 and 60+35+5, which both offer performance (gas gain and plateau) very similar to that of the baseline mixture, but at 400 V lower absolute voltages.

  17. High pressure humidification columns: Design equations, algorithm, and computer code

    Energy Technology Data Exchange (ETDEWEB)

    Enick, R.M. [Pittsburgh Univ., PA (United States). Dept. of Chemical and Petroleum Engineering; Klara, S.M. [USDOE Pittsburgh Energy Technology Center, PA (United States); Marano, J.J. [Burns and Roe Services Corp., Pittsburgh, PA (United States)

    1994-07-01

    This report describes the detailed development of a computer model to simulate the humidification of an air stream in contact with a water stream in a countercurrent, packed tower, humidification column. The computer model has been developed as a user model for the Advanced System for Process Engineering (ASPEN) simulator. This was done to utilize the powerful ASPEN flash algorithms as well as to provide ease of use when using ASPEN to model systems containing humidification columns. The model can easily be modified for stand-alone use by incorporating any standard algorithm for performing flash calculations. The model was primarily developed to analyze Humid Air Turbine (HAT) power cycles; however, it can be used for any application that involves a humidifier or saturator. The solution is based on a multiple stage model of a packed column which incorporates mass and energy, balances, mass transfer and heat transfer rate expressions, the Lewis relation and a thermodynamic equilibrium model for the air-water system. The inlet air properties, inlet water properties and a measure of the mass transfer and heat transfer which occur in the column are the only required input parameters to the model. Several example problems are provided to illustrate the algorithm`s ability to generate the temperature of the water, flow rate of the water, temperature of the air, flow rate of the air and humidity of the air as a function of height in the column. The algorithm can be used to model any high-pressure air humidification column operating at pressures up to 50 atm. This discussion includes descriptions of various humidification processes, detailed derivations of the relevant expressions, and methods of incorporating these equations into a computer model for a humidification column.

  18. Experimental research on short-term feeding of dust contaminated gas to a molten carbonate fuel cell cathode

    Science.gov (United States)

    Bernat, Rafał; Milewski, Jarosław; Wejrzanowski, Tomasz

    2017-07-01

    The paper presents initial research on processes present on the cathode side of Molten Carbonate Fuel Cells (MCFC), when the supplied gas is an aerosol containing solid particulate matter. The research is based on experiments conducted at the Institute of Heat Engineering of Warsaw University of Technology. The main task is to determine whether and to what extent solid particles disable or hinder the operation of a molten carbonate fuel cell. It is thought that they might change the penetrability of porous layers by clogging their void volumes. Under investigation are the sizes and amount of solid particles required to significantly affect the processes occurring on the triple phase. Experimental investigation was conducted that determined the change in operational parameters due to dust contamination. Surprisingly, there is no sudden drop in the electric parameters of the fuel cell subject to dust poisoning. Supposedly, the dust creates a porous, permeable to gases, structure on the electrode. The only varying parameter was the pressure difference between the inlet and the outlet to the cathode.

  19. Gas Diffusion Electrodes Manufactured by Casting Evaluation as Air Cathodes for Microbial Fuel Cells (MFC).

    Science.gov (United States)

    Srikanth, Sandipam; Pant, Deepak; Dominguez-Benetton, Xochitl; Genné, Inge; Vanbroekhoven, Karolien; Vermeiren, Philippe; Alvarez-Gallego, Yolanda

    2016-07-21

    One of the most intriguing renewable energy production methods being explored currently is electrical power generation by microbial fuel cells (MFCs). However, to make MFC technology economically feasible, cost efficient electrode manufacturing processes need to be proposed and demonstrated. In this context, VITO has developed an innovative electrode manufacturing process based on film casting and phase inversion. The screening and selection process of electrode compositions was done based on physicochemical properties of the active layer, which in turn maintained a close relation with their composition A dual hydrophilic-hydrophobic character in the active layer was achieved with values of ε hydrophilic up to 10% while ε TOTAL remained in the range 65 wt % to 75 wt %. Eventually, selected electrodes were tested as air cathodes for MFC in half cell and full cell modes. Reduction currents, up to -0.14 mA·cm 2- at -100 mV (vs. Ag/AgCl) were reached in long term experiments in the cathode half-cell. In full MFC, a maximum power density of 380 mW·m -2 was observed at 100 Ω external load.

  20. Gas Diffusion Electrodes Manufactured by Casting Evaluation as Air Cathodes for Microbial Fuel Cells (MFC

    Directory of Open Access Journals (Sweden)

    Sandipam Srikanth

    2016-07-01

    Full Text Available One of the most intriguing renewable energy production methods being explored currently is electrical power generation by microbial fuel cells (MFCs. However, to make MFC technology economically feasible, cost efficient electrode manufacturing processes need to be proposed and demonstrated. In this context, VITO has developed an innovative electrode manufacturing process based on film casting and phase inversion. The screening and selection process of electrode compositions was done based on physicochemical properties of the active layer, which in turn maintained a close relation with their composition A dual hydrophilic-hydrophobic character in the active layer was achieved with values of εhydrophilic up to 10% while εTOTAL remained in the range 65 wt % to 75 wt %. Eventually, selected electrodes were tested as air cathodes for MFC in half cell and full cell modes. Reduction currents, up to −0.14 mA·cm2− at −100 mV (vs. Ag/AgCl were reached in long term experiments in the cathode half-cell. In full MFC, a maximum power density of 380 mW·m−2 was observed at 100 Ω external load.

  1. Evaluation of stainless steel cathodes and a bicarbonate buffer for hydrogen production in microbial electrolysis cells using a new method for measuring gas production

    KAUST Repository

    Ambler, Jack R.

    2011-01-01

    Microbial electrolysis cells (MECs) are often examined for hydrogen production using non-sustainable phosphate buffered solutions (PBS), although carbonate buffers have been shown to work in other bioelectrochemical systems with a platinum (Pt) catalyst. Stainless steel (SS) has been shown to be an effective catalyst for hydrogen evolution in MECs, but it has not been tested with carbonate buffers. We evaluated the combined using of SS cathodes and a bicarbonate buffer (BBS) at the applied voltages of 0.5, 0.7 and 0.9 V using a new inexpensive method for measuring gas production called the gas bag method (GBM). This method achieved an average error of only 5.0% based on adding known volumes of gas to the bag. Using the GBM, hydrogen production with SS and a BBS was 26.6 ± 1.8 mL which compared well to 26.4 ± 2.8 mL using Pt and BBS, and 26.8 ± 2.5 mL with a Pt cathode and PBS. Electrical energy efficiency was highest with a SS cathode and BBS at 159 ± 17%, compared to 126 ± 14% for the Pt cathode and BBS, and 134 ± 17% for a Pt cathode and PBS. The main disadvantage of the SS was a lower gas production rate of 1.1 ± 0.3 m3 H2-m-3 d-1 with BBS and 1.2 ± 0.3 m3 H2-m-3 d -1 with PBS, compared to 1.7 ± 0.4 m3 H 2-m-3 d-1 with Pt and PBS. These results show that the GBM is an effective new method for measuring gas production of anaerobic gas production processes, and that SS and bicarbonate buffers can be used to effectively produce hydrogen in MECs. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

  2. Development of a screened cathode gas flow proportional counter for in situ field determination of alpha contamination in soil

    Energy Technology Data Exchange (ETDEWEB)

    Bush, S.P.

    1997-02-01

    This study resulted in the design, construction and testing of a gas flow proportional counter for in-situ determination of soil contamination. The uniqueness of this detector is the screened material used for the cathode. A Pu-239 source of 0.006 {micro}Ci was mounted to the outside of the cathode to simulate radioactive soil. The detector probe was placed into a laboratory mock-up and tested to determine operating voltage, efficiency and energy resolution. Two gas flow proportional counters were built and tested. The detectors are cylindrical, each with a radius of 1.905 cm, having an anode wire with a radius of 0.0038 cm. The length of the smaller detector`s anode was 2.54 cm, and the length of the larger detector`s anode was 7.64 cm. Therefore, the active volumes were 28.96 cm{sup 3} and 87.10 cm{sup 3}, respectively, for the small and large detector. An operating voltage of 1,975 volts was determined to be sufficient for both detectors. The average efficiency was 2.59 {+-} 0.12% and 76.71 {+-} 10.81% for the small volume and large volume detectors, respectively. The average energy resolution for the low-energy peak of the small detector was 4.24 {+-} 1.28% and for the large-energy peak was 1.37 {+-} 0.66%. The large detectors` energy resolution was 17.75 {+-} 3.74%. The smaller detector, with better energy resolution, exhibited a bi-modal spectrum, whereas the larger detector`s spectrum centered around a single broad peak.

  3. Microbial corrosion and cracking in steel. A concept for evaluation of hydrogen-assisted stress corrosion cracking in cathodically protected high-pressure gas transmission pipelines

    DEFF Research Database (Denmark)

    Nielsen, Lars Vendelbo

    An effort has been undertaken in order to develop a concept for evaluation of the risk of hydrogen-assisted cracking in cathodically protected gas transmission pipelines. The effort was divided into the following subtasks: A. Establish a correlation between the fracture mechanical properties...... of high-strength pipeline steel and the concentration of hydrogen present in the steel. B. Determine the degree hydrogen absorption by cathodically protected steel exposed in natural soil sediment, which include activity of sulphate-reducing bacteria (SRB). C. Compare the above points with fracture...

  4. Effectiveness of Humidification with Heat and Moisture Exchanger-booster in Tracheostomized Patients.

    Science.gov (United States)

    Gonzalez, Isabel; Jimenez, Pilar; Valdivia, Jorge; Esquinas, Antonio

    2017-08-01

    The two most commonly used types of humidifiers are heated humidifiers and heat and moisture exchange humidifiers. Heated humidifiers provide adequate temperature and humidity without affecting the respiratory pattern, but overdose can cause high temperatures and humidity resulting in condensation, which increases the risk of bacteria in the circuit. These devices are expensive. Heat and moisture exchanger filter is a new concept of humidification, increasing the moisture content in inspired gases. This study aims to determine the effectiveness of the heat and moisture exchanger (HME)-Booster system to humidify inspired air in patients under mechanical ventilation. We evaluated the humidification provided by 10 HME-Booster for tracheostomized patients under mechanical ventilation using Servo I respirators, belonging to the Maquet company and Evita 4. There was an increase in the inspired air humidity after 1 h with the humidifier. The HME-Booster combines the advantages of heat and moisture exchange minimizing the negatives. It increases the amount of moisture in inspired gas in mechanically ventilated tracheostomized patients. It is easy and safe to use. The type of ventilator used has no influence on the result.

  5. A contribution to spectroscopic diagnostics and cathode sheath modeling of micro-hollow gas discharge in argon

    Energy Technology Data Exchange (ETDEWEB)

    Cvejic, M.; Spasojevic, Dj.; Sisovic, N. M.; Konjevic, N. [Faculty of Physics, University of Belgrade, P.O. Box 368, Belgrade 11001 (Serbia)

    2011-08-01

    In this paper, the hydrogen Balmer beta line shape from a micro-hollow gas discharge (MHGD) in argon with traces of hydrogen is used for simultaneous diagnostics of plasma and cathode sheath (CS) parameters. For this purpose, a simple model of relevant processes responsible for the line broadening is introduced and applied to the Balmer beta profile recorded from a MHGD generated in the microhole (diameter 100 {mu}m at narrow side and 130 {mu}m at wider side) of a gold-alumina-gold sandwich in the pressure range (100-900 mbar). The electron number density N{sub e} in the range (0.4-4.5) x 10{sup 20} m{sup -3} is determined from the width of the central part of the Balmer beta line profile, while, from the extended wings of the Balmer beta profile, induced by dc Stark effect, the next three parameters are determined: the average value E{sub a} of electric field strength in the CS in the range (16-95 kV/cm), the electric field strength E{sub 0} at the cathode surface in the range (32-190 kV/cm), and the CS thickness z{sub g} in the range (18-70 {mu}m). All four MHGD parameters, N{sub e}, E{sub a}, E{sub 0}, and z{sub g}, compare reasonably well with results of the modeling experiment by M. J. Kushner [J. Phys. D: Appl. Phys. 38, 1633 (2005)]. The results for N{sub e} are compared with other emission experiments.

  6. Evaluating a tobacco leaf humidification system involving nebulisation

    Directory of Open Access Journals (Sweden)

    Néstor Enrique Cerquera Peña

    2010-05-01

    Full Text Available A tobacco leaf humidifying system involving nebulisation was designned, implemented and evaluated; it had a system for monitoring and recording environmental conditions thereby producing an environment having more homogeneous relative humidity, ensuring better water use, better control of relative humidity and better control in managing cured tobacco leaf moisture content, thereby leading to a consequent improvement in final product quality. 55% to 75% relative humidity and 4 to 6 hour working ranges were obtained to en- sure leaf humidification reached 16% humidity on a wet basis. Two new designs are proposed for the conditioning stage regarding this conditioning chamber’s operational management, based on the results and field observations, which would allow better leaf management, thereby avoiding the risk of losses due to manipulation and over-humidification. This work strengthens research in the field of tobacco pos- tharvest technology, complementing other research projects which have been carried out in Colombia.

  7. Study of the cathode region of mercury-free He-Xe low-pressure gas-discharge lamps with planar mesh electrode; Untersuchung der Kathodenregion von quecksilberfreien He-Xe Niederdruckgasentladungslampen mit planarer Geflechtelektrode

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Joern

    2009-12-04

    In the present work the cathode region of a mercury-free helium-xenon low pressure discharge in spot mode was experimentally investigated. Due to the emission of electrons, the production of ions and metastable atoms as well as lifetime limiting processes the cathode region is of particular interest. To implement a discharge in spot mode a novel planar mesh electrode was developed and used as cathode. Applying the space resolved laser-atom-absorption-spectroscopy method (LAAS) the absolute particle densities of the two lowest excited xenon atoms and the gas temperature in the cathode region were determined, whereas the strong spot plasma inhomogeneity was considered. Both the excited xenon particle density and the gas temperature strongly decrease in radial and axial direction. Particularly the gas temperature has a value of about 650 K in a 1mm cathode distance and does clearly exceed room temperature. Furthermore the spectrum of the hot spot on the cathode surface was detected by means of optical emission spectroscopy. From this spectrum the temperature distribution of the cathode spot was obtained by fitting Planck's law. The temperature distribution shows a distinct maximum, which in dependence of the discharge current reaches values of 1414 K at 40 mA and 1524 K at 80 mA. From that maximum a steep direction-independent temperature decrease was obtained. A technological important aspect concerning the lifetime of a xenon based mercury-free discharge lamp is the problematic effect of the xenon gas consumption. In this work it is shown that in contrary to an industrial made standard cup electrode, which is broadly used in light advertising lamps, the gas consumption is negligible when applying the novel planar mesh electrode. This reduction of gas consumption is due to the generation of a hot spot along with high cathode temperature and low cathode fall voltage. (orig.)

  8. Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: External humidifier versus heat and moisture exchanger

    NARCIS (Netherlands)

    Mérol, Jean-Claude; Charpiot, Anne; Langagne, Thibault; Hémar, Patrick; Ackerstaff, Annemieke H.; Hilgers, Frans J. M.

    2012-01-01

    Objectives/Hypothesis: Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Study Design: Randomized controlled trial (RCT). Methods: Fifty-three

  9. Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: external humidifier versus heat and moisture exchanger

    NARCIS (Netherlands)

    Mérol, J.-C.; Charpiot, A.; Langagne, T.; Hémar, P.; Ackerstaff, A.H.; Hilgers, F.J.M.

    2012-01-01

    Objectives/Hypothesis: Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Study Design: Randomized controlled trial (RCT). Methods: Fifty-three

  10. Generation, utilization, and transformation of cathode electrons for bioreduction of Fe(III)EDTA in a biofilm electrode reactor related to NOx removal from flue gas.

    Science.gov (United States)

    Li, Wei; Xia, Yinfeng; Zhao, Jingkai; Liu, Nan; Li, Sujing; Zhang, Shihan

    2015-04-07

    A chemical absorption-biological reduction (CABR) integrated system, which employs iron chelate as a solvent, is under development for NOx removal from flue gas. Biofilm electrode reactor (BER) is deemed as a promising bioreactor to regenerate the iron chelate. Although it has been proved that BER can significantly enhance the bioreduction of Fe(III)EDTA, the bioelectrochemistry mechanism involved in the bioreduction of Fe(III)EDTA remains unknown. This work aims to explore this mechanism via the analysis of the generation, utilization, and transformation of cathode electrons in the BER. The results indicate that the generation of cathode electrons follows Faraday's law. The generated cathode electrons were used to produce H2 and directly reduce Fe(III)EDTA in the BER. Meanwhile, the produced H2 served as an electron donor for bioreduction of Fe(III)EDTA. The excess H2 product was transformed to simple organics, e.g., methanol by the hydrogen autotrophy of Pseudomonas under the inorganic and anaerobic conditions. Overall, this work revealed that the reduction of Fe(III)EDTA in the BER was enhanced by both direct electrochemical reduction and indirect bioreduction using H2 as an intermediate. It is also interesting that the excess H2 product was transformed to methanol for microbial metabolism and energy storage in the BER.

  11. Insufficient Humidification of Respiratory Gases in Patients Who Are Undergoing Therapeutic Hypothermia at a Paediatric and Adult Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Yukari Tanaka

    2017-01-01

    Full Text Available For cooled newborn infants, humidifier settings for normothermic condition provide excessive gas humidity because absolute humidity at saturation is temperature-dependent. To assess humidification of respiratory gases in patients who underwent moderate therapeutic hypothermia at a paediatric/adult intensive care unit, 6 patients were studied over 9 times. Three humidifier settings, 37-default (chamber-outlet, 37°C; Y-piece, 40°C, 33.5-theoretical (chamber-outlet, 33.5°C; Y-piece, 36.5°C, and 33.5-adjusted (optimised setting to achieve saturated vapour at 33.5°C using feedback from a thermohygrometer, were tested. Y-piece gas temperature/humidity and the incidence of high (>40.6 mg/L and low (<32.9 mg/L humidity relative to the target level (36.6 mg/L were assessed. Y-piece gas humidity was 32.0 (26.8–37.3, 22.7 (16.9–28.6, and 36.9 (35.5–38.3 mg/L {mean (95% confidence interval} for 37-default setting, 33.5-theoretical setting, and 33.5-adjusted setting, respectively. High humidity was observed in 1 patient with 37-default setting, whereas low humidity was seen in 5 patients with 37-default setting and 8 patients with 33.5-theoretical setting. With 33.5-adjusted setting, inadequate Y-piece humidity was not observed. Potential risks of the default humidifier setting for insufficient respiratory gas humidification were highlighted in patients cooled at a paediatric/adult intensive care unit. Y-piece gas conditions can be controlled to the theoretically optimal level by adjusting the setting guided by Y-piece gas temperature/humidity.

  12. Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

    KAUST Repository

    Ahn, Yongtae

    2014-02-01

    To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m -2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation. © 2013 Elsevier B.V. All rights reserved.

  13. [Humidification assessment of four heat and moisture exchanger filters according to ISO 9360: 2000 standard].

    Science.gov (United States)

    Lannoy, D; Décaudin, B; Resibois, J-P; Barrier, F; Wierre, L; Horrent, S; Batt, C; Moulront, S; Odou, P

    2008-02-01

    This work consisted of the assessment of humidification parameters and flow resistance for different heat and moisture exchanger filters (HMEF) used in intensive care unit. Four electrostatic HMEF were assessed: Hygrobac S (Tyco); Humidvent compact S (Teleflex); Hygrovent S/HME (Medisize-Dräger); Clear-Therm+HMEF (Intersurgical). Humidification parameters (loss of water weight, average absolute moisture [AAM], absolute variation of moisture) have been evaluated on a bench-test in conformity with the ISO 9360: 2000 standard, for 24h with the following ventilatory settings: tidal volume at 500 ml, respiratory rate at 15 c/min, and inspiration/expiration ratio at 1:1. The flow resistance of HMEFs assessed using the pressure drop method was measured before and after 24h of humidification for three increasing air flows of 30, 60, and 90 l/min. All the HMEFs allowed satisfactory level of humidification exceeding 30 mgH(2)O/l. The less powerful remained the Clear-Therm. Concerning HMEFs flow resistance, results showed a pressure drop slightly more important for the Hygrobac S filter as compared with other filters. This test showed differences between the HMEFs for both humidification and resistance parameters. When compared to the new version of the standards, HMEFs demonstrated their reliability. However, evolution of humidification and flow resistance characteristics over 24h showed a structural degradation of HMEFs, limiting their use over a longer period.

  14. Energy-Saving Benefits of Adiabatic Humidification in the Air Conditioning Systems of Semiconductor Cleanrooms

    Directory of Open Access Journals (Sweden)

    Min-Suk Jo

    2017-11-01

    Full Text Available This paper aimed to evaluate the applicability of adiabatic humidification in the heating, ventilation, and air conditioning (HVAC systems of semiconductor cleanrooms. Accurate temperature and humidity control are essential in semiconductor cleanrooms and high energy consumption steam humidification is commonly used. Therefore, we propose an adiabatic humidification system employing a pressurized water atomizer to reduce the energy consumption. The annual energy consumption of three different HVAC systems were analyzed to evaluate the applicability of adiabatic humidification. The studied cases were as follows: (1 CASE 1: a make-up air unit (MAU with a steam humidifier, a dry cooling coil (DCC, and a fan filter unit (FFU; (2 CASE 2: a MAU with the pressurized water atomizer, a DCC, and a FFU; and (3 CASE 3: a MAU, a DCC, and a FFU, and the pressurized water atomizer installed in the return duct. The energy saving potential of adiabatic humidification over steam humidification has been proved, with savings of 8% and 23% in CASE 2 and CASE 3 compared to CASE 1, respectively. Furthermore, the pressurized water atomizer installed in the return duct exhibits greater energy saving effect than when installed in the MAU.

  15. Cathodic arcs

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2003-10-29

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas standout due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bias. Industrial processes often use cathodic arc plasma in reactive mode. In contrast, the science of arcs has focused on the case of vacuum arcs. Future research directions include closing the knowledge gap for reactive mode, large area coating, linear sources and filters, metal plasma immersion process, with application in high-tech and biomedical fields.

  16. Umidificação e aquecimento do gás inalado durante ventilação artificial com baixo fluxo e fluxo mínimo de gases frescos Humidificación y calentamiento del gas inhalado durante ventilación artificial con bajo flujo y flujo mínimo de gases frescos Inhaled gases humidification and heating during artificial ventilation with low flow and minimal fresh gases flow

    Directory of Open Access Journals (Sweden)

    Susane Bruder Silveira Gorayb

    2004-02-01

    calentamiento del gas inhalado son necesarios para la prevención de lesiones en el sistema respiratorio, consecuentes al contacto del gas frío y seco con las vías aéreas. El objetivo de la pesquisa fue evaluar el efecto del sistema respiratorio circular con absorbedor de dióxido de carbono del aparato de anestesia Cícero de Dräger, cuanto a la capacidad de calentamiento y humidificación de los gases inhalados, utilizándose flujo bajo (1 L.min-1 o mínimo (0,5 L.min-1 de gases frescos. MÉTODO: El estudio aleatorio fue realizado en 24 pacientes estado físico ASA I, con edades entre 18 y 65 años, sometidos a anestesia general, utilizándose la Estación de Trabajo Cícero de Dräger (Alemania, para realización de cirugías abdominales, los cuales fueron distribuidos aleatoriamente en dos grupos: grupo de Bajo Flujo (BF, en el cual fue administrado 0,5 L.min-1 de oxígeno y 0,5 L.min-1 de óxido nitroso y flujo mínimo (FM, administrándose solamente oxígeno a 0,5 L.min-1. Los atributos estudiados fueron: temperatura, humedad relativa y absoluta de la sala de operación y del gas en el sistema inspiratorio. RESULTADOS: Los valores de la temperatura, humedad relativa y humedad absoluta en el sistema inspiratorio en la salida del aparato de anestesia y junto al tubo traqueal no presentaron diferencia significante entre los grupos, pero aumentaron a lo largo del tiempo en los dos grupos (BF y FM, habiendo influencia de la temperatura de la sala de operación sobre la temperatura del gas inhalado, en los dos grupos estudiados. Niveles de humedad y temperatura próximos de los ideales fueron alcanzados, en los dos grupos, a partir de 90 minutos. CONCLUSIONES: No hay diferencia significante de la humedad y temperatura del gas inhalado utilizándose bajo flujo y flujo mínimo de gases frescos.BACKGROUND AND OBJECTIVES: Inhaled gas humidification and heating are necessary in patients under tracheal intubation or tracheostomy to prevent damage to respiratory system resulting

  17. Solar Desalination by Humidification-Dehumidification of Air

    Directory of Open Access Journals (Sweden)

    Moumouh J.

    2018-01-01

    Full Text Available The importance of supplying potable water can hardly be overstressed. In many arid zones, coastal or inlands, seawater or brackish water desalination may be the only solution to the shortage of fresh water. The process based on humidification-dehumidification of air (HDH principle mimic the natural water cycle. HDH technique has been subjected to many studies in recent years due to the low temperature, renewable energy use, simplicity, low cost installation and operation. An experimental test set-up has been fabricated and assembled. The prototype equipped with appropriate measuring and controlling devices. Detailed experiments have been carried out at various operating conditions. The heat and mass transfer coefficients have been obtained experimentally. The results of the investigation have shown that the system productivity increases with the increase in the mass flow rate of water through the unit. Water temperature at condenser exit increases linearly with water temperature at humidifier inlet and it decreases as water flow rate increases. HDH desalination systems realised on also work at atmospheric pressure; hence they do not need mechanical energy except for circulation pumps and fans. These kinds of systems are suitable for developing countries. The system is modular, it is possible to increase productivity with additional solar collectors and additional HDH cycles.

  18. Effect of O2/Ar Gas Flow Ratios on Properties of Cathodic Vacuum Arc Deposited ZnO Thin Films on Polyethylene Terephthalate Substrate

    Directory of Open Access Journals (Sweden)

    Chien-Wei Huang

    2016-01-01

    Full Text Available Cathodic vacuum arc deposition (CVAD can obtain a good quality thin film with a low growth temperature and a high deposition rate, thus matching the requirement of film deposition on flexible electronics. This paper reported the room-temperature deposition of zinc oxide (ZnO thin films deposited by CVAD on polyethylene terephthalate (PET substrate. Microstructure, optical, and electrical measurements of the deposited ZnO thin films were investigated with various O2/Ar gas flow ratios from 6 : 1 to 10 : 1. The films showed hexagonal wurtzite crystal structure. With increasing the O2/Ar gas flow ratios, the c-axis (002 oriented intensity decreased. The crystal sizes were around 16.03 nm to 23.42 nm. The average transmittance values in the visible range of all deposited ZnO films were higher than 83% and the calculated band gaps from the absorption data were found to be around 3.1 to 3.2 eV. The resistivity had a minimum value in the 3.65 × 10−3 Ω·cm under the O2/Ar gas flow ratio of 8 : 1. The luminescence mechanisms of the deposited film were also investigated to understand the defect types of room-temperature grown ZnO films.

  19. Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

    Science.gov (United States)

    Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

    2017-11-01

    The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

  20. Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

    Science.gov (United States)

    Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

    2018-01-01

    The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

  1. A Critical Review of Published Data on the Gas Temperature and the Electron Density in the Electrolyte Cathode Atmospheric Glow Discharges

    Directory of Open Access Journals (Sweden)

    Tamás Cserfalvi

    2012-05-01

    Full Text Available Electrolyte Cathode Discharge (ELCAD spectrometry, a novel sensitive multielement direct analytical method for metal traces in aqueous solutions, was introduced in 1993 as a new sensing principle. Since then several works have tried to develop an operational mechanism for this exotic atmospheric glow plasma technique, however these attempts cannot be combined into a valid model description. In this review we summarize the conceptual and technical problems we found in this upcoming research field of direct sensors. The TG gas temperature and the ne electron density values published up to now for ELCAD are very confusing. These data were evaluated by three conditions. The first is the gas composition of the ELCAD plasma, since TG was determined from the emitted intensity of the N2 and OH bands. Secondly, since the ELCAD is an atmospheric glow discharge, thus, the obtained TG has to be close to the Te electron temperature. This can be used for the mutual validation of the received temperature data. Thirdly, as a consequence of the second condition, the values of TG and ne have to agree with the Engel-Brown approximation of the Saha-equation related to weakly ionized glow discharge plasmas. Application of non-adequate experimental methods and theoretical treatment leads to unreliable descriptions which cannot be used to optimize the detector performance.

  2. Thermoeconomic Optimization of a Combined Heating and Humidification Coil for HVAC Systems

    Science.gov (United States)

    Teodoros, Liliana; Andresen, Bjarne

    2016-07-01

    The total cost of ownership is calculated for a combined heating and humidification coil of an air-handling unit taking into account investment and operation costs simultaneously. This total cost represents the optimization function for which the minimum is sought. The parameters for the cost dependencies are the physical dimensions of the coil: length, width and height. The term "coil" is used generically since in this setup it generates heating as well as humidification in a single unit. The first part of the paper deals with the constructive optimization and finds the relationship between the dimensions for a minimum cost. The second part of the paper takes the results of the constructive optimization further and, based on the data derived in our previous papers, analyzes the minimum total cost for the humidification coil while balancing the amount of water used to humidify the air and modify its temperature.

  3. Modelling of a cathode-supported tubular solid oxide fuel cell operating with biomass-derived synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Suwanwarangkul, R. [School of Bio-Chemical Engineering and Technology, Sirindhorn International Institute of Technology, Thammasart University-Rangsit Campus, Pathum Thani 12121 (Thailand); Croiset, E.; Pritzker, M.D.; Fowler, M.W.; Douglas, P.L. [Department of Chemical Engineering, University of Waterloo, Waterloo, Ont. N2L 3G1 (Canada); Entchev, E. [Advance Combustion Technologies Laboratory, CANMET Energy Technology Centre, 1 Haanel Drive, Ottawa, Ont. K1A 1M1 (Canada)

    2007-04-15

    A mechanistic model for the operation of a tubular solid oxide fuel cell (SOFC) using synthesis gas as a fuel source has been successfully developed and validated against experimental data reported in the literature. The model considers momentum-, mass-, energy- and charge-transport equations coupled with electrochemical and water-gas shift reactions. This avoids the use of empirical correlations for estimating heat and mass transfer coefficients. The model is solved to predict SOFC performance and behavior by determining the distributions of current density, temperature and species concentrations throughout the cell. The developed model was used to predict the effect of the composition of biomass-derived synthesis gas fuels on cell performance and behavior. (author)

  4. An experimental study of the air humidification process using a membrane contactor

    Directory of Open Access Journals (Sweden)

    Englart Sebastian

    2017-01-01

    Full Text Available The article presents the results of the experimental examination of the effectiveness of air humidification using a membrane module. The construction of the membrane module and the measuring stand is also discussed. In order to assess the effectiveness of air humidification using the membrane module, the measurements of temperature and humidity at the membrane module’s inlet and outlet, air flow rate, water flow rate and water temperature were taken. Based on the measurements, the effectiveness coefficients, E, have been determined. The power demand for the solution under study has also been discussed.

  5. Assessing environmental performance of humidification technology used in supply of fresh fruit and vegetables

    DEFF Research Database (Denmark)

    Fabbri, Serena; Owsianiak, Mikolaj

    -harvest losses of fruit and vegetables. Humidifiers release a fine mist thereby reducing the difference in water vapour pressure at the surface of the fruit or vegetable and in the air, preventing dry-out of fruits and deterioration. In addition, humidification provides cooling as a result of the evaporation...... is driven by the humidifier production and disposal stages rather than agriculture. Thus, depending on the performance of humidifying units, humidification may have the potential to reduce environmental impacts stemming from supply of fresh fruit and vegetables in Europe....

  6. Cathode fall measurements in fluorescent lamps

    Energy Technology Data Exchange (ETDEWEB)

    Nachtrieb, Robert [Lutron Electronics Co Inc., 7200 Suter Rd., Coopersburg, PA 18036 (United States); Khan, Farheen [Lutron Electronics Co Inc., 7200 Suter Rd., Coopersburg, PA 18036 (United States); Waymouth, John F [Consultant, 16 Bennett Rd. Marblehead, MA 01945 (United States)

    2005-09-07

    We describe an improved method and apparatus for making capacitive measurements of the cathode fall in fluorescent lamps employing known behaviour of anode oscillations to provide a zero-of-potential reference, placing the entire cathode and anode fall waveform on an absolute rather than relative scale. The improved method is applicable to any diameter of fluorescent lamp currently manufactured. We also describe a method and apparatus for making spectroscopic measurements of the cathode fall in fluorescent lamps. This uses the abrupt onset of emission of certain selected spectral lines of the rare gas filling as a signal that the cathode fall has exceeded the excitation potentials of the spectral lines in question.

  7. Local impact of humidification on degradation in polymer electrolyte fuel cells

    Science.gov (United States)

    Sanchez, Daniel G.; Ruiu, Tiziana; Biswas, Indro; Schulze, Mathias; Helmly, Stefan; Friedrich, K. Andreas

    2017-06-01

    The water level in a polymer electrolyte membrane fuel cell (PEMFC) affects the durability as is seen from the degradation processes during operation a PEMFC with fully- and nonhumidified gas streams as analyzed using an in-situ segmented cell for local current density measurements during a 300 h test operating under constant conditions and using ex situ SEM/EDX and XPS post-test analysis of specific regions. The impact of the RH on spatial distribution of the degradation process results from different water distribution giving different chemical environments. Under nonhumidified gas streams, the cathode inlet region exhibits increased degradation, whereas with fully humidified gases the bottom of the cell had the higher performance losses. The degradation and the degree of reversibility produced by Pt dissolution, PTFE defluorination, and contaminants such as silicon (Si) and nickel (Ni) were locally evaluated.

  8. INTENSE ENERGETIC GAS DISCHARGE

    Science.gov (United States)

    Luce, J.S.

    1960-03-01

    A method and apparatus for initiating and sustaining an energetic gas arc discharge are described. A hollow cathode and a hollow anode are provided. By regulating the rate of gas flow into the interior of the cathode, the arc discharge is caused to run from the inner surface of the cathode with the result that adequate space-charge neutralization is provided inside the cathode but not in the main arc volume. Thus, the gas fed to the cathode is substantially completely ionized before it leaves the cathode, with the result that an energetic arc discharge can be maintained at lower operating pressures.

  9. Elastomeric Cathode Binder

    Science.gov (United States)

    Yen, S. P. S.; Shen, D. S.; Somoano, R. B.

    1985-01-01

    Soluble copolymer binder mixed with cathode material and solvent forms flexible porous cathode used in lithium and Ni/Cd batteries. Cathodes prepared by this process have lower density due to expanding rubbery binder and greater flexibility than conventional cathodes. Fabrication procedure readily adaptable to scaled-up processes.

  10. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  11. Humidification Technique Using New Modified MiniModule Membrane Contactors for Air Cooling

    OpenAIRE

    Mohamed Ali; Obida Zeitoun; Hany Al-Ansary; Abdullah Nuhait

    2013-01-01

    An experimental study is conducted to cool the ambient air using a new humidification technique. A wind tunnel is built with a test section formed by four modified MiniModule membrane contactors. An ambient air passes over the membrane contactors (cross flow) while water pumps through the contactors. Air temperature and relative humidity are measured upstream and downstream of the membrane contactors array which was used to humidify and cool the outdoor air. Five average air velocities (3.03,...

  12. Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li-Ni-Mn-Co-O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Strafela, Marc; Fischer, Julian; Leiste, Harald; Rinke, Monika; Bergfeldt, Thomas; Seifert, Hans Juergen; Ulrich, Sven [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Applied Materials (IAM); Music, Denis; Chang, Keke; Schneider, Jochen [RWTH Aachen Univ. (Germany). Materials Chemistry

    2017-11-15

    Li(Ni{sub 1/3}Mn{sub 1/3}Co{sub 1/3})O{sub 2} as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g{sup -1}), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li-Ni-Mn-Co-O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li{sub 1.18}(Ni{sub 0.39}Mn{sub 0.19}Co{sub 0.35})O{sub 1.97} target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li-Ni-Mn-Co-O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

  13. Remote monitoring of cathodic protection rectifiers of the Bolivia-Brazil Gas Pipeline using low orbit satellite telephone; Monitoracao remota de retificadores de protecao catodica do Gasoduto Bolivia-Brasil utilizando telefone via satelite de baixa orbita

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Jorge Fernando Pereira [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    The present paper has for objective to present the information collected during definitions, development, implementation, testing and operation phases of the Pilot System for monitoring of the Cathodic Protection Rectifiers MS-10 and SP-09, installed on the Bolivia-Brazil Gas Pipeline. The adopted solution for the Pilot System includes, basically, communication through low-earth satellite telephone, inter linked to the public telephone net, acquisition and data transmission system (Remote Terminal Unit) and data reception in the Supervision and Control Room. (author)

  14. Co-Flow Hollow Cathode Technology

    Science.gov (United States)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  15. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  16. Heated humidification improves clinical outcomes, compared to a heat and moisture exchanger in children with tracheostomies.

    Science.gov (United States)

    McNamara, David G; Asher, M Innes; Rubin, Bruce K; Stewart, Alistair; Byrnes, Catherine A

    2014-01-01

    The upper airway humidifies and warms inspired gases before they reach the trachea, a process bypassed by the insertion of a tracheostomy, necessitating humidification of inspired gases. The optimal method of humidification is not known. We conducted a short-term 20-hour study and a long-term 10-week randomized crossover study comparing a heated humidifier (HH) to a heat and moisture exchanger (HME) in children with established tracheostomies. Subjects were assessed for clinical events, clinical examination findings, airway cytokine levels, and airway secretion viscoelasticity. For the short-term study, 15 children were recruited; for the long-term study, 14 children were recruited. Children using the HH had decreased respiratory examination score (P < .001) but no change in clinical events over the short term. There was a decrease in acute clinical events (P = .008) in the long-term study. No differences were found in airway secretion viscoelasticity results or cytokine levels in either study, but these sample numbers were limited. Over 20 hours use, HH, compared to HME, improved work of breathing. Over a longer 10 week treatment period HH resulted in decreased adverse clinical events.

  17. Closed-Loop Control of Humidification for Artifact Reduction in Capacitive ECG Measurements.

    Science.gov (United States)

    Leicht, Lennart; Eilebrecht, Benjamin; Weyer, Soren; Leonhardt, Steffen; Teichmann, Daniel

    2017-04-01

    Recording biosignals without the need for direct skin contact offers new opportunities for ubiquitous health monitoring. Electrodes with capacitive coupling have been shown to be suitable for the monitoring of electrical potentials on the body surface, in particular ECG. However, due to triboelectric charge generation and motion artifacts, signal and thus diagnostic quality is inferior to galvanic coupling. Active closed-loop humidification of capacitive electrodes is proposed in this work as a new concept to improve signal quality. A capacitive ECG recording system integrated into a common car seat is presented. It can regulate the micro climate at the interface of electrode and patient by actively dispensing water vapour and monitoring humidity in a closed-loop approach. As a regenerative water reservoir, silica gel is used. The system was evaluated with respect to subjective and objective ECG signal quality. Active humidification was found to have a significant positive effect in case of previously poor quality. Also, it had no diminishing effect in case of already good signal quality.

  18. Cathodic Protection Model Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Performs Navy design and engineering of ship and submarine impressed current cathodic protection (ICCP) systems for underwater hull corrosion control and...

  19. Randomized controlled trial on postoperative pulmonary humidification after total laryngectomy: external humidifier versus heat and moisture exchanger.

    Science.gov (United States)

    Mérol, Jean-Claude; Charpiot, Anne; Langagne, Thibault; Hémar, Patrick; Ackerstaff, Annemieke H; Hilgers, Frans J M

    2012-02-01

    Assessment of immediate postoperative airway humidification after total laryngectomy (TLE), comparing the use of an external humidifier (EH) with humidification through a heat and moisture exchanger (HME). Randomized controlled trial (RCT). Fifty-three patients were randomized into the standard (control) EH (N = 26) or the experimental HME arm (N = 27). Compliance, pulmonary and sleeping problems, patients' and nursing staff satisfaction, nursing time, and cost-effectiveness were assessed with trial-specific structured questionnaires and tally sheets. In the EH arm data were available for all patients, whereas in the HME arm data were incomplete for four patients. The 24/7 compliance rate in the EH arm was 12% and in the HME arm 87% (77% if the four nonevaluable patients are considered noncompliant). Compliance and patients' satisfaction were significantly better, and the number of coughing episodes, mucus expectoration for clearing the trachea, and sleeping disturbances were significantly less in the HME arm (P < .001). This was also the case for nursing time and nursing staff satisfaction and preference. This RCT clearly shows the benefits of immediate postoperative airway humidification by means of an HME over the use of an EH after TLE. This study therefore underlines that HMEs presently can be considered the better option for early postoperative airway humidification after TLE. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

  20. Cathode erosion in high-current high-pressure arc

    CERN Document Server

    Nemchinsky, V A

    2003-01-01

    Cathode erosion rate was experimentally investigated for two types of arcs: one with tungsten cathode in nitrogen atmosphere and one with hafnium cathode in oxygen atmosphere. Conditions were typical for plasma arc cutting systems: gas pressure from 2 to 5 atm, arc current from 200 to 400 A, gas flow rate from 50 to 130 litre min sup - sup 1. It was found that the actual cathode evaporation rate G is much lower than G sub 0 , the evaporation rate that follows from the Hertz-Knudsen formula: G = nu G sub 0. The difference is because some of the evaporated particles return back to the cathode. For conditions of our experiments, the factor nu could be as low as 0.01. It was shown experimentally that nu depends strongly on the gas flow pattern close to the cathode. In particular, swirling the gas increases nu many times. To explain the influence of gas swirling, model calculations of gas flows were performed. These calculations revealed difference between swirling and non-swirling flows: swirling the gas enhances...

  1. Heated humidification versus heat and moisture exchangers for ventilated adults and children.

    Science.gov (United States)

    Kelly, Margaret; Gillies, Donna; Todd, David A; Lockwood, Catherine

    2010-10-01

    Humidification by artificial means must be provided when the upper airway is bypassed during mechanical ventilation. Heated humidification (HH) and heat and moisture exchangers (HMEs) are the most commonly used types of artificial humidification in this situation. To determine whether HHs or HMES are more effective in preventing mortality and other complications in people who are mechanically ventilated. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 4) and MEDLINE, EMBASE and CINAHL (January, 2010) to identify relevant randomized controlled trials. We included randomized controlled trials comparing HMEs to HHs in mechanically ventilated adults and children. We included randomized crossover studies. We assessed the quality of each study and extracted the relevant data. Where appropriate, results from relevant studies were meta-analyzed for individual outcomes. We included 33 trials with 2833 participants; 25 studies were parallel group design (n = 2710) and 8 crossover design (n = 123). Only 3 included studies reported data for infants or children. There was no overall effect on artificial airway occlusion, mortality, pneumonia, or respiratory complications; however, the PaCO(2) and minute ventilation were increased when HMEs were compared to HHs and body temperature was lower. The cost of HMEs was lower in all studies that reported this outcome. There was some evidence that hydrophobic HMEs may reduce the risk of pneumonia and that blockages of artificial airways may be increased with the use of HMEs in certain subgroups of patients. There is little evidence of an overall difference between HMEs and HHs. However, hydrophobic HMEs may reduce the risk of pneumonia and the use of an HMEs may increase artificial airway occlusion in certain subgroups of patients. Therefore, HMEs may not be suitable for patients with limited respiratory reserve or prone to airway blockage. Further research is needed relating to

  2. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  3. Heat and moisture exchanger: importance of humidification in anaesthesia and ventilatory breathing system.

    Science.gov (United States)

    Parmar, Vandana

    2008-08-01

    Adequate humidification is vital to maintain homeostasis of the airway. Heat and moisture exchangers conserve some of the exhaled water, heat and return them to inspired gases. Many heat and moisture exchangers also perfom bacterial/viral filtration and prevent inhalation of small particles. Heat and moisture exchangers are also called condenser humidifier, artificial nose, etc. Most of them are disposable devices with exchanging medium enclosed in a plastic housing. For adult and paediatric age group different dead space types are available. Heat and moisture exchangers are helpful during anaesthesia and ventilatory breathing system. To reduce the damage of the upper respiratory tract through cooling and dehydration inspiratory air can be heated and humidified, thus preventing the serious complications.

  4. Relative humidity control in polymer electrolyte membrane fuel cells without extra humidification

    Science.gov (United States)

    Riascos, Luis A. M.

    The performance of polymer electrolyte membrane fuel cells is highly influenced by the water content in the membrane. To prevent the membrane from drying, several researchers have proposed extra humidification on the input reactants. But in some applications, the extra size and weight of the humidifier should be avoided. In this research a control technique, which maintains the relative humidity on saturated conditions, is implemented by adjusting the air stoichiometry; the effects of drying of membrane and flooding of electrodes are considered, as well. For initial analysis, a mathematical model reveals the relationship among variables that can be difficult to monitor in a real machine. Also prediction can be tested optimizing time and resources. For instance, the effects of temperature and humidity can be analyzed separately. For experimental validation, tests in a fault tolerant fuel cell are conducted.

  5. Relative humidity control in polymer electrolyte membrane fuel cells without extra humidification

    Energy Technology Data Exchange (ETDEWEB)

    Riascos, Luis A.M. [Federal University of ABC, r. Santa Adelia 166, CEP 09210-170, Santo Andre, SP (Brazil)

    2008-09-15

    The performance of polymer electrolyte membrane fuel cells is highly influenced by the water content in the membrane. To prevent the membrane from drying, several researchers have proposed extra humidification on the input reactants. But in some applications, the extra size and weight of the humidifier should be avoided. In this research a control technique, which maintains the relative humidity on saturated conditions, is implemented by adjusting the air stoichiometry; the effects of drying of membrane and flooding of electrodes are considered, as well. For initial analysis, a mathematical model reveals the relationship among variables that can be difficult to monitor in a real machine. Also prediction can be tested optimizing time and resources. For instance, the effects of temperature and humidity can be analyzed separately. For experimental validation, tests in a fault tolerant fuel cell are conducted. (author)

  6. Effect on air quality and flow rate of fresh water production in humidification and dehumidification system

    Science.gov (United States)

    Rajasekar, K.; Pugazhenthi, R.; Selvaraju, A.; Manikandan, T.; Saravanan, R.

    2017-03-01

    Water is the vital need of any living organisms of the world when water fails, functions of nature cease the world. The water scarcity is one of the major problems to be faced by the developing world, which indicates a critical need to develop inexpensive small-scale desalination technologies. The cost of the desalination process takes more, so the world expecting the desalination plants with minimum operating cost, so the utilization of renewable energy source is a preferable one. This research article provides a glimpse of an overview of the humidification-dehumidification (HDH) based desalination method which uses the solar energy. The HDH based desalination method monitored and evaluated the performance parameters, i.e. mass flow rates of water and air.

  7. Measured and modeled humidification factors of fresh smoke particles from biomass burning: role of inorganic constituents

    Directory of Open Access Journals (Sweden)

    J. L. Hand

    2010-07-01

    Full Text Available During the 2006 FLAME study (Fire Laboratory at Missoula Experiment, laboratory burns of biomass fuels were performed to investigate the physico-chemical, optical, and hygroscopic properties of fresh biomass smoke. As part of the experiment, two nephelometers simultaneously measured dry and humidified light scattering coefficients (bsp(dry and bsp(RH, respectively in order to explore the role of relative humidity (RH on the optical properties of biomass smoke aerosols. Results from burns of several biomass fuels from the west and southeast United States showed large variability in the humidification factor (f(RH=bsp(RH/bsp(dry. Values of f(RH at RH=80–85% ranged from 0.99 to 1.81 depending on fuel type. We incorporated measured chemical composition and size distribution data to model the smoke hygroscopic growth to investigate the role of inorganic compounds on water uptake for these aerosols. By assuming only inorganic constituents were hygroscopic, we were able to model the water uptake within experimental uncertainty, suggesting that inorganic species were responsible for most of the hygroscopic growth. In addition, humidification factors at 80–85% RH increased for smoke with increasing inorganic salt to carbon ratios. Particle morphology as observed from scanning electron microscopy revealed that samples of hygroscopic particles contained soot chains either internally or externally mixed with inorganic potassium salts, while samples of weak to non-hygroscopic particles were dominated by soot and organic constituents. This study provides further understanding of the compounds responsible for water uptake by young biomass smoke, and is important for accurately assessing the role of smoke in climate change studies and visibility regulatory efforts.

  8. Liquid water quantification in the cathode side gas channels of a proton exchange membrane fuel cell through two-phase flow visualization

    Science.gov (United States)

    Banerjee, Rupak; Kandlikar, Satish G.

    2014-02-01

    Water management is crucial to the performance of PEM fuel cells. Water is generated as part of the electrochemical reaction, and is removed through the reactant channels. This results in two-phase flow in the reactant channels. Increased understanding of the behavior of the liquid water in the channels allows us to devise better strategies for managing the water content inside the fuel cell. Most previous work has been focused on qualitative information regarding flow pattern maps. The current work presents new algorithms developed in MATLAB® to quantify the liquid water and to identify the flow patterns in the cathode side reactant channels. Parallel channels with dimensions matching those of commercial stacks have been used in this study. The liquid water present in the reactant channels is quantified for different temperature, inlet RH and current density conditions, and the results are presented in terms of area coverage ratio. The dominant flow patterns for the different conditions have been mapped, and trends interpreted on the basis of air flow velocities and saturation conditions within the channels.

  9. Cathodic dissolution in the electrocoagulation process using aluminium electrodes.

    Science.gov (United States)

    Picard, T; Cathalifaud-Feuillade, G; Mazet, M; Vandensteendam, C

    2000-02-01

    All the authors working with aluminium electrodes in the electrocoagulation process have shown that a dissolution occurs at the cathode. This result cannot be explained by the electrochemical process in which only the anodes should be dissolved. The most probable reaction is a chemical attack by hydroxyl ions (generated during water reduction) on the aluminium cathode but nobody has proved it in the framework of the electrocoagulation process. So we are interested in determining what kind of reactions occurs at the cathode. For that, we have elaborated a batch pilot apparatus divided into two compartments, allowing measurement of gas formation taking place only in one compartment. The gases measurements were performed by mass spectrometry with helium as carrier gas. To validate our experimental protocol, the first experiments have been done with a stainless steel cathode: in this case, the results have indicated that the amount of created hydrogen is in good agreement with the values calculated using the second Faraday's law. The experiments realised with an aluminium cathode have shown that the hydrogen formation, in these conditions, was higher than those observed with the stainless steel cathode. All our investigations enable us to propose that with an aluminium cathode, hydrogen formation can be separated into two phenomena. The first one is due to an electrochemical reaction (water reduction), and the second one arises from a chemical reaction explaining the dissolution observed at the cathode.

  10. Improved cathode materials for microbial electrosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T; Nie, HR; Bain, TS; Lu, HY; Cui, MM; Snoeyenbos-West, OL; Franks, AE; Nevin, KP; Russell, TP; Lovley, DR

    2013-01-01

    Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode-microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6-7 fold and modification with 3-aminopropyltriethoxysilane gave rates 3-fold higher than untreated controls. A 3-fold increase in electrosynthesis over untreated carbon cloth cathodes was also achieved with polyaniline cathodes. However, not all strategies to provide positively charged surfaces were successful, as treatment of carbon cloth with melamine or ammonia gas did not stimulate acetate electrosynthesis. Treating carbon cloth with metal, in particular gold, palladium, or nickel nanoparticles, also promoted electrosynthesis, yielding electrosynthesis rates that were 6-,4.7- or 4.5-fold faster than the untreated control, respectively. Cathodes comprised of cotton or polyester fabric treated with carbon nanotubes yielded cathodes that supported acetate electrosynthesis rates that were similar to 3-fold higher than carbon cloth controls. Recovery of electrons consumed in acetate was similar to 80% for all materials. The results demonstrate that one approach to increase rates of carbon dioxide reduction in microbial electrosynthesis is to modify cathode surfaces to improve microbe-electrode interactions.

  11. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  12. Nanostructured sulfur cathodes.

    Science.gov (United States)

    Yang, Yuan; Zheng, Guangyuan; Cui, Yi

    2013-04-07

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes.

  13. Combined novel methods for the determination of the humidification conditions of polymer electrolyte fuel cells; Kombination neuer Methoden zur Bestimmung des Wasserhaushaltes von Polymer-Elektrolyt-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Robert Martin

    2011-05-02

    The water management is one of the key factors for the performance of a low temperature PEM fuel cell. With respect to the optimization of the fuel cell operation it is important to detect and differentiate water in the membrane, in the gas diffusion layer (GDL) and excess water in the flow field channel. The water content of each component influences the performance in different ways and adapted operation modes have to be kept. This work entitled 'Combined novel methods for the determination of the humidification conditions of PEM fuel cells' provides techniques and guidelines for fuel cell operation and will conclude in a straightforward control and operation strategy. Based on a combination of electrochemical impedance spectroscopy (EIS), locally resolved current distribution measurements and neutron radiography an informative basis for the determination of the water content of an operating PEM fuel cell is created. Special attention has been paid to the reproducibility and comparability in order to set up a consistent investigation and control strategy. (orig.)

  14. Solar collector exergetic optimization for a multi effect humidification desalination prototype

    Directory of Open Access Journals (Sweden)

    R González-Acuña

    2016-09-01

    Full Text Available Venezuela is a country with a great deal of water resources. In spite of this, about 1.6 million inhabitants are dispersed in remote regions where water distribution is problematic due to the lack of this resource. A flat plate solar collector was built as a component of a single-stage Multi-Effect Humidification (MEH desalination plant prototype, and its characterization was done on a testing rig designed and constructed according to the ANSI/ASHRAE 93-2003 standards. In order to optimize the operation of this equipment, the exergetic change of the working fluid across the solar collector was maximized. This objective was accomplished through a numerical simulation of the solar collector performance using a predictive algorithm and available yearlong meteorological data. It was found that a mass flow rate equal to 0.006 kg/s (0.36 LPM should be maintain to ensure the maximum exergetic gain of the working fluid for an inlet temperature of 54°C.

  15. Influence of vapor absorption cooling on humidification-dehumidification (HDH desalination

    Directory of Open Access Journals (Sweden)

    C. Chiranjeevi

    2016-09-01

    Full Text Available The desalination yield in humidification-dehumidification (HDH process is increased by proposing cooling plant integration with two stage operation. The current work is targeted on the investigation of vapor absorption refrigeration (VAR parameters on overall energy utilization factor (EUF. The dephlegmator heat is recovered internally in VAR instead of rejecting to environment. This work can be used to control the operational conditions of VAR to enhance the desalination and cooling together. The studied process parameters in VAR are strong solution concentration, separator or generator temperature, dephlegmator effectiveness, circulating water inlet temperature and evaporator temperature. Out of these five variables, lower limit of separator temperature, upper limit of dephlegmator effectiveness and lower limit of circulating water temperature are fixed in the specified range to attain the optimum strong solution concentration and optimum evaporator temperature. At the specified boundaries of three variables, the optimized strong solution concentration and evaporator temperature are 0.47 and 10 °C respectively. At this condition, the maximized cycle EUF is 0.358.

  16. Automatic humidification system to support the assessment of food drying processes

    Science.gov (United States)

    Ortiz Hernández, B. D.; Carreño Olejua, A. R.; Castellanos Olarte, J. M.

    2016-07-01

    This work shows the main features of an automatic humidification system to provide drying air that match environmental conditions of different climate zones. This conditioned air is then used to assess the drying process of different agro-industrial products at the Automation and Control for Agro-industrial Processes Laboratory of the Pontifical Bolivarian University of Bucaramanga, Colombia. The automatic system allows creating and improving control strategies to supply drying air under specified conditions of temperature and humidity. The development of automatic routines to control and acquire real time data was made possible by the use of robust control systems and suitable instrumentation. The signals are read and directed to a controller memory where they are scaled and transferred to a memory unit. Using the IP address is possible to access data to perform supervision tasks. One important characteristic of this automatic system is the Dynamic Data Exchange Server (DDE) to allow direct communication between the control unit and the computer used to build experimental curves.

  17. Lanthanum Manganate Based Cathodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Jørgensen, Mette Juhl

    medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple......Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained...... phase boundary between electrode, electrolyte and gas phase, was found. Suggestions for further experiments and for modelling of the oxygen reduction mechanism are given....

  18. Highly Efficient Micro Cathode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek Company, Inc. proposes to develop a micro thermionic cathode that requires extremely low power and provides long lifetime. The basis for the cathode is a...

  19. Advanced Cathode Electrolyzer (ACE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a static, cathode-fed, 2000 psi, balanced-pressure Advanced Cathode Electrolyzer (ACE) based on PEM electrolysis technology. It...

  20. Miniaturized cathodic arc plasma source

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  1. Cathode material for lithium batteries

    Science.gov (United States)

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  2. Mechanism analysis of Gen Ⅲ LLL image intensifier GaAs cathode photoelectric emission disability

    Science.gov (United States)

    Xu, Jiangtao; Yan, Lei; Cheng, Yaojin; Han, Kunye; Liu, Beibei; Zhang, Taimin

    2013-08-01

    The focus of the third generation image intensifier photocathode sensitivity decreases in the GaAs are analyzed, and proposed solutions,experimental results show that the tube microchannel plate(mcp), screen GaAs cathode discharge gas is caused by decreased sensitivity of the main reasons. Paper used two-layer model, and even negative electron affinity(NET) interface barrier theory of the photoelectric cathode drop mechanism was discussed , when the photocathode emission levels of CO adsorption and other harmful gas, chemical adsorption layer of ionic bond formation will lead to production of cathode surface barrier interfaces. Cathode surface adsorption of the pollutants more ,the interface barrier becomes thicker, the smaller the electron surface escape probability, when the cathode interface thicker barrier to the electron surface escape is zero, the cathode photoemission end of life.

  3. Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

    Directory of Open Access Journals (Sweden)

    Sang Soon Hwang

    2009-11-01

    Full Text Available In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

  4. Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels.

    Science.gov (United States)

    Lee, Pil Hyong; Hwang, Sang Soon

    2009-01-01

    In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0-100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

  5. Explosive Processes on Cathode while Forming Nanosecond Pulsed Discharge of High Pressure

    Directory of Open Access Journals (Sweden)

    A. Hashimov

    2012-01-01

    Full Text Available The paper is devoted to research of cathode surfaces with different curvature radius (r = 1–8 mm while forming nanosecond pulsed discharge in dense air. Influence of field and air pressure heterogeneity rate in gas gap on size of micro-craters being formed on working cathode surface after pulsed effect has been shown in the paper. The paper reveals a maximum expansion of separate micro-crater size on cathode surface with small curvature radius.

  6. Emission characteristics of laser ablation-hollow cathode glow discharge spectral source

    Directory of Open Access Journals (Sweden)

    Karatodorov Stefan

    2014-11-01

    Full Text Available The emission characteristics of a scheme combining laser ablation as sample introduction source and hollow cathode discharge as excitation source are presented. The spatial separation of the sample material introduction by laser ablation and hollow cathode excitation is achieved by optimizing the gas pressure and the sample-cathode gap length. At these conditions the discharge current is maximized to enhance the analytical lines intensity.

  7. DARHT 2 kA Cathode Development

    Energy Technology Data Exchange (ETDEWEB)

    Henestroza, E.; Houck, T.; Kwan, J.W.; Leitner, M.; Miram, G.; Prichard, B.; Roy, P.K.; Waldron, W.; Westenskow, G.; Yu, S.; Bieniosek, F.M.

    2009-03-09

    value). We reexamined all the components in the cathode region and eliminated those parts that were suspected to be potential sources of contamination, e.g., feed-throughs with zinc coating. Finally, we considered a change in the cathode type, by using a different combination of impregnation and coating. Since the ETA-II accelerator at LLNL used a 12.5 cm diameter 311XW (barium oxide doped with scandium and coated with a osmium-tungsten thin film) cathode and emitted 2200A of beam current (i.e. 18 A/cm{sup 2}), it was reasonable to assume that DARHT can adopt this type of cathode to produce 2 kA (i.e., 10A/cm{sup 2}). However, it was later found that the 311XW has a higher radiation heat loss than the 612M and therefore resulted in a maximum operating temperature (as limited by filament damage) below that required to produce the high current. With the evidence provided by systematic emission tests using quarter-inch size cathodes, we confirmed that the 311XM (doped with scandium and has a osmium-ruthenium (M) coating) had the best combination of low work function and low radiation heat loss. Subsequently a 6.5-inch diameter 311XM cathode was installed in DARHT and 2 kA beam current was obtained on June 14, 2007. In testing the quarter-inch size cathode, we found that the beam current was sensitive to the partial pressure of various gases in the vacuum chamber. Furthermore, there was a hysteresis effect on the emission as a function of temperature. The phenomenon suggested that the work function of the cathode was dependent on the dynamic equilibrium between the diffusion of the impregnated material to the surface and the contamination rate from the surrounding gas. Water vapor was found to be the worst contaminant amongst the various gases that we have tested. Our data showed that the required vacuum for emitting at 10 A/cm{sup 2} is in the low 10{sup -8} Torr range.

  8. Web-Based Cathode Strip Chamber Data Display

    CERN Multimedia

    Firmansyah, M

    2013-01-01

    Cathode Strip Chamber (CSC) is a detector that uses gas and high electric field to detect particles. When a particle goes through CSC, it will ionize gas particles and generate electric signal in the anode and cathode of the detector. Analysis of the electric signal data can help physicists to reconstruct path of the particles and determine what happen inside the detector. Using data display, analysis of CSC data becomes easier. One can determine which data is interesting, unusual, or maybe only contain noise.\

  9. Separation of Electrolytic Reduction Product from Stainless Steel Wire Mesh Cathode Basket via Salt Draining and Reuse of the Cathode Basket

    National Research Council Canada - National Science Library

    Eun-Young Choi; Jeong Lee; Dong Hyun Heo; Jin-Mok Hur

    2017-01-01

    .... Platinum was employed as an anode. After the electrolysis, the residual salt of the cathode basket containing the reduction product was drained by placing it at gas phase above the molten salt using a holder...

  10. Importance of OH(-) transport from cathodes in microbial fuel cells.

    Science.gov (United States)

    Popat, Sudeep C; Ki, Dongwon; Rittmann, Bruce E; Torres, César I

    2012-06-01

    Cathodic limitation in microbial fuel cells (MFCs) is considered an important hurdle towards practical application as a bioenergy technology. The oxygen reduction reaction (ORR) needs to occur in MFCs under significantly different conditions compared to chemical fuel cells, including a neutral pH. The common reason cited for cathodic limitation is the difficulty in providing protons to the catalyst sites. Here, we show that it is not the availability of protons, but the transport of OH(-) from the catalyst layer to the bulk liquid that largely governs cathodic potential losses. OH(-) is a product of an ORR mechanism that has not been considered dominant before. The accumulation of OH(-) at the catalyst sites results in an increase in the local cathode pH, resulting in Nernstian concentration losses. For Pt-based gas-diffusion cathodes, using polarization curves developed in unbuffered and buffered solutions, we quantified this loss to be >0.3 V at a current density of 10 Am(-2) . We show that this loss can be partially overcome by replacing the Nafion binder used in the cathode catalyst layer with an anion-conducting binder and by providing additional buffer to the cathode catalyst directly in the form of CO(2) , which results in enhanced OH(-) transport. Our results provide a comprehensive analysis of cathodic limitations in MFCs and should allow researchers to develop and select materials for the construction of MFC cathodes and identify operational conditions that will help minimize Nernstian concentration losses due to pH gradients. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres.

    Science.gov (United States)

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-25

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

  12. The use of hollow cathodes in deposition processes: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Muhl, Stephen, E-mail: muhl@unam.mx; Pérez, Argelia

    2015-03-31

    The first report of a discharge in a hollow cathode was by F. Paschen in 1916. That study showed that such a system was capable of producing a high electron flux and relatively low ion and neutral temperatures. About 40 years later, the work of Lidsky and others showed that hollow cathode arc discharges were one of the best plasma sources available at that time. The term “hollow cathode discharges” has commonly been used in reference to almost any discharge in a cathode with a cavity-like geometry, such that the plasma was enclosed or partially bound by the electrode walls that were at the cathode potential. Just as the magnetic field trapping of the electrons in a magnetron cathode results in an increase in the plasma density, in the hollow cathode, the reduced electron loss due to the geometry of the cathode also results in a higher plasma density. At least three types of discharge can be established in a hollow cathode. At low power and/or at relatively low gas pressures, the plasma is a “conventional” discharge characterized by low currents and medium to high voltages (we will call this a discharge in a hollow cathode or D-HC). Even this type of plasma has a higher density than a normal planar parallel-plate or magnetron system because the hollow geometry strongly reduces the loss of electrons. Using an adequate combination of gas pressure and applied power with a given hollow cathode diameter, or separation of the cathode surface, the negative glow of the plasma can expand to occupy the majority of the interior volume of the cathode. Under this condition the plasma current can, for the same voltage, be 100 to 1000 times the value of the “simple” D-HC discharge, and the plasma density is correspondingly larger (we call this a hollow cathode discharge or HCD). If the cathode is not cooled, the discharge can transform into a dispersed arc as the electrode temperature increases and thermal-field electron emission becomes an important additional source

  13. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    YongMan Choi; Meilin Liu

    2006-09-30

    This DOE SECA project focused on both experimental and theoretical understanding of oxygen reduction processes in a porous mixed-conducting cathode in a solid oxide fuel cell (SOFC). Elucidation of the detailed oxygen reduction mechanism, especially the rate-limiting step(s), is critical to the development of low-temperature SOFCs (400 C to 700 C) and to cost reduction since much less expensive materials may be used for cell components. However, cell performance at low temperatures is limited primarily by the interfacial polarization resistances, specifically by those associated with oxygen reduction at the cathode, including transport of oxygen gas through the porous cathode, the adsorption of oxygen onto the cathode surface, the reduction and dissociation of the oxygen molecule (O{sub 2}) into the oxygen ion (O{sup 2-}), and the incorporation of the oxygen ion into the electrolyte. In order to most effectively enhance the performance of the cathode at low temperatures, we must understand the mechanism and kinetics of the elementary processes at the interfaces. Under the support of this DOE SECA project, our accomplishments included: (1) Experimental determination of the rate-limiting step in the oxygen reduction mechanism at the cathode using in situ FTIR and Raman spectroscopy, including surface- and tip-enhanced Raman spectroscopy (SERS and TERS). (2) Fabrication and testing of micro-patterned cathodes to compare the relative activity of the TPB to the rest of the cathode surface. (3) Construction of a mathematical model to predict cathode performance based on different geometries and microstructures and analyze the kinetics of oxygen-reduction reactions occurring at charged mixed ionic-electronic conductors (MIECs) using two-dimensional finite volume models with ab initio calculations. (4) Fabrication of cathodes that are graded in composition and microstructure to generate large amounts of active surface area near the cathode/electrolyte interface using a

  14. Exposure and acute exposure-effects before and after modification of a contaminated humidification system in a synthetic-fibre plant

    NARCIS (Netherlands)

    Pal, TM; de Monchy, JGR; Groothoff, JW; Post, D

    Objective: Follow-up study of exposure and acute exposure-effects after modification to steam humidification of a contaminated cold water system which had caused an outbreak of humidifier fever in a synthetic-fibre plant. Methods: Before and after modification of the system aerobiological

  15. Follow-up study of workers in a nylon carpet yarn plant after remedial actions taken against a contaminated humidification system

    NARCIS (Netherlands)

    Pal, TM; Groothoff, JW; Post, D; de Monchy, JGR

    Objective: To investigate the effectiveness of remedial actions taken against a contaminated humidification system, after an outbreak of humidifier disease in a nylon carpet yam plant. Methods: Two and 6 years after modification, a follow-up investigation of a strati tied (age, smoking habits)

  16. Pressurized air cathodes for enhanced stability and power generation by microbial fuel cells

    KAUST Repository

    He, Weihua

    2016-09-30

    Large differences between the water and air pressure in microbial fuel cells (MFCs) can deform and damage cathodes. To avoid deformation, the cathode air pressure was controlled to balance pressure differences between the air and water. Raising the air pressures from 0 to 10 kPa at a set cathode potential of −0.3 V (versus Ag/AgCl) enhanced cathode performance by 17%, but pressures ≥25 kPa decreased current and resulted in air leakage into the solution. Matching the air pressure with the water pressure avoided cathode deformation and improved performance. The maximum power density increased by 15%, from 1070 ± 20 to 1230 ± 70 mW m, with balanced air and water pressures of 10–25 kPa. Oxygen partial pressures ≥12.5 kPa in the cathode compartment maintained the oxygen reduction rate to be within 92 ± 1% of that in ambient air. The use of pressurized air flow through the cathode compartments can enable closer spacing of the cathodes compared to passive gas transfer systems, which could make the reactor design more compact. The energy cost of pressurizing the cathodes was estimated to be smaller than the increase in power that resulted from the use of pressurized cathodes.

  17. Explosive Processes on Cathode while Forming Nanosecond Pulsed Discharge of High Pressure

    National Research Council Canada - National Science Library

    A. Hashimov; R. Mekhtizadeh; А. Bondyakov; Sh. Kazimov

    2012-01-01

    ...) while forming nanosecond pulsed discharge in dense air. Influence of field and air pressure heterogeneity rate in gas gap on size of micro-craters being formed on working cathode surface after pulsed effect has been shown in the paper...

  18. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

    Wang, Wei Guo; Liu, Yi-Lin; Barfod, Rasmus

    2005-01-01

    that the (La1-xSrx)(y)MnO3 +/-delta (LSM) composite cathodes consist of a network of homogenously distributed LSM, yttria-stabilized zirconia (YSZ), and pores. The individual grain size of LSM or YSZ is approximately 100 nm. The degree of contact between cathode and electrolyte is 39% on average. (c) 2005...

  19. Degradation characteristics of air cathode in zinc air fuel cells

    Science.gov (United States)

    Ma, Ze; Pei, Pucheng; Wang, Keliang; Wang, Xizhong; Xu, Huachi; Liu, Yongfeng; peng, Guanlin

    2015-01-01

    The zinc air fuel cell (ZAFC) is a promising candidate for electrical energy storage and electric vehicle propulsion. However, its limited durability has become a major obstacle for its successful commercialization. In this study, 2-cell stacks, 25 cm² cells and three-electrode half-cells are constructed to experimentally investigate the degradation characteristics of the air cathode. The results of electrochemical tests reveal that the peak power density for the 25 cm2 cell with a new air cathode is 454 mW cm-2, which is twice as the value of the used air cathode. The electrochemical impedance analysis shows that both the charge transfer resistance and the mass transfer resistance of the used air cathodes have increased, suggesting that the catalyst surface area and gas diffusion coefficient have decreased significantly. Additionally, the microstructure and morphology of the catalytic layer (CL) and gas diffusion layer (GDL) are characterized by scanning electron microscopes (SEM). SEM results confirm that the micropores in CL and GDL of the used air cathode are seriously clogged, and many catalyst particles are lost. Therefore, the performance degradation is mainly due to the clogging of micropores and loss of catalyst particles. Furthermore, hypotheses of degradation mechanism and mitigation strategies for GDL and CL are discussed briefly.

  20. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  1. A Transient Model for Fuel Cell Cathode-Water Propagation Behavior inside a Cathode after a Step Potential

    Directory of Open Access Journals (Sweden)

    Der-Sheng Chan

    2010-04-01

    Full Text Available Most of the voltage losses of proton exchange membrane fuel cells (PEMFC are due to the sluggish kinetics of oxygen reduction on the cathode and the low oxygen diffusion rate inside the flooded cathode. To simulate the transient flooding in the cathode of a PEMFC, a transient model was developed. This model includes the material conservation of oxygen, vapor, water inside the gas diffusion layer (GDL and micro-porous layer (MPL, and the electrode kinetics in the cathode catalyst layer (CL. The variation of hydrophobicity of each layer generated a wicking effect that moves water from one layer to the other. Since the GDL, MPL, and CL are made of composite materials with different hydrophilic and hydrophobic properties, a linear function of saturation was used to calculate the wetting contact angle of these composite materials. The balance among capillary force, gas/liquid pressure, and velocity of water in each layer was considered. Therefore, the dynamic behavior of PEMFC, with saturation transportation taken into account, was obtained in this study. A step change of the cell voltage was used to illustrate the transient phenomena of output current, water movement, and diffusion of oxygen and water vapor across the entire cathode.

  2. Phenomenology of plasma engine cathodes at high current rates and low pressures

    Science.gov (United States)

    Huegel, H.; Kruelle, G.

    1984-01-01

    The effects of low surrounding pressures on cathodes of arc jet engines with electromagnetic acceleration are investigated for pressure and current energies of 20 to 100 Torr. and 400 to 1000 A. Experiments with 50 mm long and 8 mm diameter tungsten-thorium cathode in a coaxial gas flow show that pre-heating of the cathode reduces the duration of the instable arc discharge and thus material loss. The use of lighter gases also reduces instability effects, as well as the use of increased pressures and a massive gas influx.

  3. Magnetron priming by multiple cathodes

    Science.gov (United States)

    Jones, M. C.; Neculaes, V. B.; Lau, Y. Y.; Gilgenbach, R. M.; White, W. M.; Hoff, B. W.; Jordan, N. M.

    2005-08-01

    A relativistic magnetron priming technique using multiple cathodes is simulated with a three-dimensional, fully electromagnetic, particle-in-cell code. This technique is based on electron emission from N /2 individual cathodes in an N-cavity magnetron to prime the π mode. In the case of the six-cavity relativistic magnetron, π-mode start-oscillation times are reduced up to a factor of 4, and mode competition is suppressed. Most significantly, the highest microwave field power is observed by utilizing three cathodes compared to other recently explored priming techniques.

  4. Multiple Hollow Cathode Wear Testing for the Space Station Plasma Contactor

    Science.gov (United States)

    Soulas, George C.

    1994-01-01

    A wear test of four hollow cathodes was conducted to resolve issues associated with the Space Station plasma contactor. The objectives of this test were to evaluate unit-to-unit dispersions, verify the transportability of contamination control protocols developed by the project, and to evaluate cathode contamination control and activation procedures to enable simplification of the gas feed system and heater power processor. These objectives were achieved by wear testing four cathodes concurrently to 2000 hours. Test results showed maximum unit-to-unit deviations for discharge voltages and cathode tip temperatures to be +/-3 percent and +/-2 percent, respectively, of the nominal values. Cathodes utilizing contamination control procedures known to increase cathode lifetime showed no trends in their monitored parameters that would indicate a possible failure, demonstrating that contamination control procedures had been successfully transferred. Comparisons of cathodes utilizing and not utilizing a purifier or simplified activation procedure showed similar behavior during wear testing and pre- and post-test performance characterizations. This behavior indicates that use of simplified cathode systems and procedures is consistent with long cathode lifetimes.

  5. Measurement and analysis of thermal photoemission from a dispenser cathode

    Directory of Open Access Journals (Sweden)

    Kevin L. Jensen

    2003-08-01

    Full Text Available Photocathodes for free electron lasers (FELs are required to produce nano-Coulomb pulses in picosecond time scales with demonstrable reliability, lifetime, and efficiency. Dispenser cathodes, traditionally a rugged and long-lived thermionic source, are under investigation to determine their utility as a photocathode and have shown promise. The present study describes theoretical models under development to analyze experimental data from dispenser cathodes and to create predictive time-dependent models to predict their performance as an FEL source. Here, a steady-state model of a dispenser cathode with partial coverage of a low work function coating and surface nonuniformity is developed. Quantitative agreement is found for experimental data, especially with regard to temperature, field, laser intensity, and quantum efficiency versus laser wavelength dependence. In particular, for long wavelength incident lasers of sufficient intensity, the majority of the absorbed energy heats the electron gas and background lattice, and photoemission from the heated electron distribution constitutes the emitted current.

  6. Phase 3 Trial of Domiciliary Humidification to Mitigate Acute Mucosal Toxicity During Radiation Therapy for Head-and-Neck Cancer: First Report of Trans Tasman Radiation Oncology Group (TROG) 07.03 RadioHUM Study

    Energy Technology Data Exchange (ETDEWEB)

    Macann, Andrew, E-mail: amacann@adhb.govt.nz [Department of Radiation Oncology, Auckland City Hospital, Auckland (New Zealand); Fua, Tsien [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Milross, Chris G. [Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, New South Wales (Australia); Porceddu, Sandro V. [Oncology Services, Princess Alexandra Hospital, Woolloongabba, Queensland (Australia); Penniment, Michael [Radiation Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia); Wratten, Chris [Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales (Australia); Krawitz, Hedley [Department of Radiation Oncology, Auckland City Hospital, Auckland (New Zealand); Poulsen, Michael [Department of Radiation Oncology, Radiation Oncology Mater Centre, South Brisbane, Queensland (Australia); Tang, Colin I. [Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia (Australia); Morton, Randall P. [Department of Otorhinolaryngology, Middlemore Hospital, Otahuhu, Auckland (New Zealand); Hay, K. David [Department of Oral Health, Auckland City Hospital, Auckland (New Zealand); Thomson, Vicki [Department of Otorhinolaryngology, Auckland City Hospital, Auckland (New Zealand); Bell, Melanie L.; King, Madeleine T. [Psycho-oncology Cooperative Research Group, Univerity of Sydney, Sydney, New South Wales (Australia); Fraser-Browne, Carol L. [Adult Oncology Research Centre, Auckland City Hospital, Auckland (New Zealand); Hockey, Hans-Ulrich P. [Biometrics Matters Ltd, Hamilton (New Zealand)

    2014-03-01

    Purpose: To assess the impact of domicile-based humidification on symptom burden during radiation therapy (RT) for head-and-neck (H and N) cancer. Methods and Materials: From June 2007 through June 2011, 210 patients with H and N cancer receiving RT were randomized to either a control arm or to receive humidification using the Fisher and Paykel Healthcare MR880 humidifier. Humidification commenced on day 1 of RT and continued until Common Terminology Criteria for Adverse Events (CTCAE), version 3.0, clinical mucositis (CMuc) grade ≤1 occurred. Forty-three patients (42%) met a defined benchmark for humidification compliance and contributed to per protocol (PP) analysis. Acute toxicities, hospitalizations, and feeding tube events were recorded prospectively. The McMaster University Head and Neck Radiotherapy Questionnaire (HNRQ) was used for patient-reported outcomes. The primary endpoint was area under the curve (AUC) for CMuc grade ≥2. Results: There were no significant differences in AUC for CMuc ≥2 between the 2 arms. Humidification patients had significantly fewer days in hospital (P=.017). In compliant PP patients, the AUC for CTCAE functional mucositis score (FMuc) ≥2 was significantly reduced (P=.009), and the proportion who never required a feeding tube was significantly greater (P=.04). HNRQ PP analysis estimates also in the direction favoring humidification with less symptom severity, although differences at most time points did not reach significance. Conclusions: TROG 07.03 has provided efficacy signals consistent with a role for humidification in reducing symptom burden from mucositis, but the influence of humidification compliance on the results moderates recommendations regarding its practical utility.

  7. External CO2 and water supplies for enhancing electrical power generation of air-cathode microbial fuel cells.

    Science.gov (United States)

    Ishizaki, So; Fujiki, Itto; Sano, Daisuke; Okabe, Satoshi

    2014-10-07

    Alkalization on the cathode electrode limits the electrical power generation of air-cathode microbial fuel cells (MFCs), and thus external proton supply to the cathode electrode is essential to enhance the electrical power generation. In this study, the effects of external CO2 and water supplies to the cathode electrode on the electrical power generation were investigated, and then the relative contributions of CO2 and water supplies to the total proton consumption were experimentally evaluated. The CO2 supply decreased the cathode pH and consequently increased the power generation. Carbonate dissolution was the main proton source under ambient air conditions, which provides about 67% of total protons consumed for the cathode reaction. It is also critical to adequately control the water content on the cathode electrode of air-cathode MFCs because the carbonate dissolution was highly dependent on water content. On the basis of these experimental results, the power density was increased by 400% (143.0 ± 3.5 mW/m(2) to 575.0 ± 36.0 mW/m(2)) by supplying a humid gas containing 50% CO2 to the cathode chamber. This study demonstrates that the simultaneous CO2 and water supplies to the cathode electrode were effective to increase the electrical power generation of air-cathode MFCs for the first time.

  8. HUMIDIFICATION AS A FACTOR OF STRUCTURIAL ORGANIZATION OF BIRD POPULATIONS IN THE WOOD STANDS OF THE BIOSPHERE RESERVE ASKANIA NOVA

    Directory of Open Access Journals (Sweden)

    M. A. Listopadsky

    2014-04-01

    Full Text Available The influence of different humidification types towards appearance of forest vegetation conditions on spatial organization of birds in the wood stands is analyzed. Population density, coefficient of occurrence, and informative connection with six types of soil humidification are given for 53 bird species. The informative estimation of every humidification type is determined for every bird species. Thereby it is definitely a contribution of every gradation of edaphic factor to the structural genesis of dendrophilous bird communities. The strongest informative connection between humidity gradients and the avifauna structure of the wood stands is available in dry edaphotopes for margin representatives and fresh one for typical forest species. These two humidification types play a start function in the structural genesis of some blocks of dendrophilous bird communities per se. It is determined that change of bird species of forest-steppe faunogenetic complex by species from Nemoral complex undergoes in most cases on the border of the gradient between fresh and humid edaphotopes. For 53 species of birds from dendrophilous complex is was revealed that the importance of different levels of soil moisture has a different impact in shaping of the modern structure dendrophilous avifauna. Dry and especially drily edaphotopes determine the spatial structure of the species that are of forest-steppe origin and belong to the representatives of the optional component of dendrophilous bird communities. Wet edafotopes are involved in the formation of the spatial structure of species of predominantly immoral origin and relate to the obligate component of representatives of dendrophilous bitd comminities. Gradient wetting of edaphotopes on the verge of ‘linked’/’fresh’ is restructuring for the bird communities. It takes an optional replacement red communists feature to obligate. Stands rather dry and fresh items currently being the most active formation of

  9. Improved Cathode Structure for a Direct Methanol Fuel Cell

    Science.gov (United States)

    Valdez, Thomas; Narayanan, Sekharipuram

    2005-01-01

    An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been

  10. The protective effect of different airway humidification liquids to lung after tracheotomy in traumatic brain injury: The role of pulmonary surfactant protein-A (SP-A).

    Science.gov (United States)

    Su, Xinyang; Li, Zefu; Wang, Meilin; Li, Zhenzhu; Wang, Qingbo; Lu, Wenxian; Li, Xiaoli; Zhou, Youfei; Xu, Hongmei

    2016-02-10

    The purpose of this study was to establish a rat model of a brain injury with tracheotomy and compared the wetting effects of different airway humidification liquids, afterward, the best airway humidification liquid was selected for the clinical trial, thus providing a theoretical basis for selecting a proper airway humidification liquid in a clinical setting. Rats were divided into a sham group, group A (0.9% NaCl), group B (0.45% NaCl), group C (0.9% NaCl+ambroxol) and group D (0.9% NaCl+Pulmicort). An established rat model of traumatic brain injury with tracheotomy was used. Brain tissue samples were taken to determine water content, while lung tissue samples were taken to determine wet/dry weight ratio (W/D), histological changes and expression levels of SP-A mRNA and SP-A protein. 30 patients with brain injury and tracheotomy were selected and divided into two groups based on the airway humidification liquid instilled in the trachea tube, 0.45% NaCl and 0.9% NaCl+ambroxol. Blood was then extracted from the patients to measure the levels of SP-A, interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α). The difference between group C and other groups in lung W/D and expression levels of SP-A mRNA and SP-A protein was significant (P<0.05). In comparison, the histological changes showed that the lung tissue damage was smallest in group C compared to the three other groups. Aspect of patients, 0.45% NaCl group and 0.9% NaCl+ambroxol group were significantly different in the levels of SP-A, IL-6, IL-8 and TNF-α (P<0.01). In the present study, 0.9% NaCl+ambroxol promote the synthesis and secretion of pulmonary surfactant, and has anti-inflammatory and antioxidant effects, which inhibit the release of inflammatory factors and cytokines, making it an ideal airway humidification liquid. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Evaluation of low-cost cathode catalysts for high yield biohydrogen production in microbial electrolysis cell.

    Science.gov (United States)

    Wang, L; Chen, Y; Ye, Y; Lu, B; Zhu, S; Shen, S

    2011-01-01

    As an ideal fuel due to the advantages of no pollution, high combustion heat and abundant sources, hydrogen gas can be produced from organic matter through the electrohydrogenesis process in microbial electrolysis cells. But in many MECs, platinum is often used as catalyst, which limits the practical applications of MECs. To reduce the cost of the MECs, Ni-based alloy cathodes were developed by electrodepositing. In this paper hydrogen production using Ni-W-P cathode was studied for the first time in a single-chamber membrane-free MEC. At an applied voltage of 0.9 V, MECs with Ni-W-P cathodes obtained a hydrogen production rate of 1.09 m3/m3/day with an cathodic hydrogen recovery of 74%, a Coulombic efficiency of 56% and an electrical energy efficiency relative to electrical input of 139%, which was the best result of reports in this study. The Ni-W-P cathode demonstrated a better electrocatalytic activity than the Ni-Ce-P cathode and achieved a comparable performance to the Pt cathode in terms of hydrogen production rate, Coulombic efficiency, cathodic hydrogen recovery and electrical energy efficiency at 0.9 V.

  12. Efficiency investigation of a new-design air solar plate collector used in a humidification-dehumidification desalination process

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Amara, Mahmoud; Houcine, Imed; Guizani, Aman-Allah; Maalej, Mohammed [Institut National de Recherche Scientifique et Tecnique, Hammam-Lif (Tunisia)

    2005-07-01

    The aim of this research is to experimentally study the efficiency of a new-design plate collector used to heat air in a new desalination humidification-dehumidification process. In fact, in such processes, the air solar collectors work at unusual experimental parameters (forced convection, elevated air humidity, high solar irradiation). At these stressed experimental conditions, few published works are available in literature. Furthermore, the comparison of the efficiency of collectors running with normal air humidity content (about 10-20 g kg{sup -1}) and air of elevated humidity (20-50 g kg{sup -1}) have not been published to our knowledge. In the present investigation, a new air solar plate collector was designed and developed for its use in a desalination process. Moreover, a characterization of such collector was performed under different experimental conditions. The effect of different parameters, namely: the solar radiation, the wind velocity, the ambient temperature, the air mass flow rate, the inlet air humidity and temperature, on the collector efficiency was also investigated. The collector was optimized for its use in a new solar desalination process. In fact, the air solar collector was designed in order to lower its economic cost making them applicable for water desalination. (Author)

  13. HUMIDIFICATION AS A FACTOR OF STRUCTURIAL ORGANIZATION OF BIRD POPULATIONS IN THE WOOD STANDS OF THE BIOSPHERE RESERVE ASKANIA NOVA

    Directory of Open Access Journals (Sweden)

    Listopadsky M. A.

    2014-04-01

    Full Text Available The influence of different humidification types towards appearance of forest vegetation conditions on spatial organization of birds in the wood stands is analyzed. Population density, coefficient of occurrence, and informative connection with six types of soil humidification are given for 53 bird species. The informative estimation of every humidification type is determined for every bird species. Thereby it is definitely a contribution of every gradation of edaphic factor to the structural genesis of dendrophilous bird communities. The strongest informative connection between humidity gradients and the avifauna structure of the wood stands is available in dry edaphotopes for margin representatives and fresh one for typical forest species. These two humidification types play a start function in the structural genesis of some blocks of dendrophilous bird communities per se. It is determined that change of bird species of forest-steppe faunogenetic complex by species from Nemoral complex undergoes in most cases on the border of the gradient between fresh and humid edaphotopes. For 53 species of birds from dendrophilous complex is was revealed that the importance of different levels of soil moisture has a different impact in shaping of the modern structure dendrophilous avifauna. Dry and especially drily edaphotopes determine the spatial structure of the species that are of forest-steppe origin and belong to the representatives of the optional component of dendrophilous bird communities. Wet edafotopes are involved in the formation of the spatial structure of species of predominantly immoral origin and relate to the obligate component of representatives of dendrophilous bitd comminities. Gradient wetting of edaphotopes on the verge of ‘linked’/’fresh’ is restructuring for the bird communities. It takes an optional replacement red communists feature to obligate. Stands rather dry and fresh items currently being the most active formation of

  14. The potential of solar-driven humidification-dehumidification desalination for small-scale decentralized water production

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, G. Prakash; Sharqawy, Mostafa H.; Summers, Edward K.; Lienhard, John H. [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge (United States); Zubair, Syed M.; Antar, M.A. [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals (Saudi Arabia)

    2010-05-15

    World-wide water scarcity, especially in the developing world, indicates a pressing need to develop inexpensive, decentralized small-scale desalination technologies which use renewable resources of energy. This paper provides a comprehensive review of the state-of-the-art in one of the most promising of these technologies, solar-driven humidification-dehumidification (HDH) desalination. Previous studies have investigated many different variations on the HDH cycle. In this paper, performance parameters which enable comparison of the various versions of the HDH cycle have been defined and evaluated. To better compare these cycles, each has been represented in psychometric coordinates. The principal components of the HDH system are also reviewed and compared, including the humidifier, solar heaters, and dehumidifiers. Particular attention is given to solar air heaters, for which design data is limited; and direct air heating is compared to direct water heating in the cycle assessments. Alternative processes based on the HDH concept are also reviewed and compared. Further, novel proposals for improvement of the HDH cycle are outlined. It is concluded that HDH technology has great promise for decentralized small-scale water production applications, although additional research and development is needed for improving system efficiency and reducing capital cost. (author)

  15. Separation of Electrolytic Reduction Product from Stainless Steel Wire Mesh Cathode Basket via Salt Draining and Reuse of the Cathode Basket

    Directory of Open Access Journals (Sweden)

    Eun-Young Choi

    2017-01-01

    Full Text Available We demonstrated that the metallic product obtained after electrolytic reduction (also called oxide reduction (OR can be simply separated from a stainless steel wire mesh cathode basket only by using a salt drain. First, the OR run of a simulated oxide fuel (0.6 kg/batch was conducted in a molten Li2O–LiCl salt electrolyte at 650°C. The simulated oxide fuel of the porous cylindrical pellets was used as a cathode by loading a stainless steel wire mesh cathode basket. Platinum was employed as an anode. After the electrolysis, the residual salt of the cathode basket containing the reduction product was drained by placing it at gas phase above the molten salt using a holder. Then, at a room temperature, the complete separation of the reduction product from the cathode basket was achieved by inverting it without damaging or deforming the basket. Finally, the emptied cathode basket obtained after the separation was reused for the second OR run by loading a fresh simulated oxide fuel. We also succeeded in the separation of the metallic product from the reused cathode basket for the second OR run.

  16. Central tracking chamber with inflated cathode-strip foils

    Science.gov (United States)

    Blackmore, E. W.; Bryman, D. A.; Kuno, Y.; Lim, C.; Numao, T.; Padley, P.; Redlinger, G.; Soluk, R.; McPherson, R. A.

    1998-02-01

    A new cylindrical low-mass central drift chamber has been constructed for the K+ → π +ν overlineν experiment at BNL (E787). The chamber consists of twelve layers of axial wire cells and six layers of thin cathode-strip foils, four of which are supported by differential gas pressure. The momentum resolution (RMS) for muons and pions in the range 150-250 MeV/ c is found to be about 0.9%.

  17. Parameter Estimates for a Polymer Electrolyte Membrane Fuel Cell Cathode

    OpenAIRE

    Guo, Qingzhi; Sethuraman, Vijay A.; White, Ralph E.

    2013-01-01

    Five parameters of a model of a polymer electrolyte membrane fuel cell cathode (the porosity of the gas diffusion layer, the porosity of the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic conductivity of the electrolyte, and the ratio of the effective diffusion coefficient of oxygen in a flooded spherical agglomerate particle to the squared particle radius) were determined by the least square fitting of experimental polarization curves. The ...

  18. Advanced Cathodes for Next Generation Electric Propulsion Technology

    Science.gov (United States)

    2008-03-01

    28 Boride Cathodes...45 Figure 15. Molybdenum Hollow Cathode Tube .............................................................. 46...CeB6 as a hollow cathode electron emitter. Additionally, all work in the US published on boride hollow cathodes are for high-current applications

  19. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a reservoir cathode to improve performance in both ion and Hall-effect thrusters. We propose to adapt our existing reservoir cathode technology to this...

  20. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a hollow reservoir cathode to improve performance in ion and Hall thrusters. We will adapt our existing reservoir cathode technology to this purpose....

  1. Mechanistic Enhancement of SOFC Cathode Durability

    Energy Technology Data Exchange (ETDEWEB)

    Wachsman, Eric [Univ. of Maryland, College Park, MD (United States)

    2016-02-01

    Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

  2. Novel Cathodes Prepared by Impregnation Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Eduardo Paz

    2006-09-30

    (1) We showed that similar results were obtained when using various LSM precursors to produce LSM-YSZ cathodes. (2) We showed that enhanced performance could be achieved by adding LSCo to LSMYSZ cathodes. (3) We have preliminary results showing that there is a slow deactivation with LSFYSZ cathodes.

  3. Measured cathode fall characteristics depending on the diameter of a hydrogen hollow cathode discharge

    Science.gov (United States)

    Gonzalez-Fernandez, V.; Grützmacher, K.; Steiger, A.; Pérez, C.; de la Rosa, M. I.

    2017-10-01

    In this work, Doppler-free two photon optogalvanic spectroscopy is used to measure the electric field strength in the cathode fall region of a hollow cathode discharge, operated in pure hydrogen, via the Stark splitting of the 2S level of atomic hydrogen. The cathode fall characteristics are analysed for various pressures and in a wide range of discharge currents. Tungsten is used as the cathode material, because it allows for reliable measurements in a fairly wide range of discharge conditions and because of its minimal sputtering. Two cathode diameters (10 mm and 15 mm) are used to study the dependence of the cathode fall on discharge geometry. The measurements reveal that the cathode fall characteristics are quite independent on the cathode diameter for equal cathode current density; hence the measurements can be used to test one dimensional modelling of the cathode fall region for low pressure hydrogen discharges using e.g. plane parallel electrodes.

  4. New design of a PEFC cathode separator of for water management

    Science.gov (United States)

    Sugiura, K.; Takahashi, N.; Kamimura, T.

    2017-11-01

    Generally, polymer electrolyte fuel cells (PEFCs) need humidifiers to prevent the drying of the membrane, but this use of humidifiers creates water management issues, such as the flooding/plugging phenomena and decreased system efficiency because of an increase in the electric energy needed for auxiliary equipment. Although most researchers have developed high-temperature membranes that do not need humidifiers, a lot of time is necessary for the development of these membranes, and these membranes drive up costs. Therefore, we propose a new cathode separator design that can recycle water generated by power generation in the same cell and a stack structure that can redistribute water collected in the cathode outlet manifold to drying cells. Because the new cathode separator has a bypass channel from the gas outlet to the gas inlet to transport excess water, a dry part in the gas inlet is supplied with excess water in the gas outlet through the bypass channel even if the PEFC is operated under dry conditions. Excess water in the PEFC stack can be transported from the cell with excess water to the drying cell through the cathode outlet manifold with a porous wall. Therefore, we confirm the influence of the plugging phenomenon in the cathode gas outlet manifold on the cell performance of each cell in the stack. As a result, the cell performance of the new cathode separator design is better than that of the standard separator under the low humidity conditions. We confirm that the plugging phenomenon in the cathode outlet manifold affects the cell performance of each cell in the stack.

  5. High surface area stainless steel brushes as cathodes in microbial electrolysis cells.

    Science.gov (United States)

    Call, Douglas F; Merrill, Matthew D; Logan, Bruce E

    2009-03-15

    Microbial electrolysis cells (MECs) are an efficient technology for generating hydrogen gas from organic matter, but alternatives to precious metals are needed for cathode catalysts. We show here that high surface area stainless steel brush cathodes produce hydrogen at rates and efficiencies similar to those achieved with platinum-catalyzed carbon cloth cathodes in single-chamber MECs. Using a stainless steel brush cathode with a specific surface area of 810 m2/m3, hydrogen was produced at a rate of 1.7 +/- 0.1 m3-H2/m3-d (current density of 188 +/- 10 A/m3) at an applied voltage of 0.6 V. The energy efficiency relative to the electrical energy input was 221 +/- 8%, and the overall energy efficiency was 78 +/- 5% based on both electrical energy and substrate utilization. These values compare well to previous results obtained using platinum on flat carbon cathodes in a similar system. Reducing the cathode surface area by 75% decreased performance from 91 +/- 3 A/m3 to 78 +/- 4 A/m3. A brush cathode with graphite instead of stainless steel and a specific surface area of 4600 m2/m3 generated substantially less current (1.7 +/- 0.0 A/m3), and a flat stainless steel cathode (25 m2/m3) produced 64 +/- 1 A/m3, demonstrating that both the stainless steel and the large surface area contributed to high current densities. Linear sweep voltammetry showed that the stainless steel brush cathodes both reduced the overpotential needed for hydrogen evolution and exhibited a decrease in overpotential over time as a result of activation. These results demonstrate for the first time that hydrogen production can be achieved at rates comparable to those with precious metal catalysts in MECs without the need for expensive cathodes.

  6. Simulation of Magnetohydrodynamic Multiphase Flow Phenomena and Interface Fluctuation in Aluminum Electrolytic Cell with Innovative Cathode

    Science.gov (United States)

    Wang, Qiang; Li, Baokuan; He, Zhu; Feng, Naixiang

    2013-12-01

    A three-dimensional (3D) transient mathematical model has been developed to understand the effect of innovative cathode on molten cryolite (bath)/molten aluminum (metal) interface fluctuation as well as energy-saving mechanism in aluminum electrolytic cell with innovative cathode. Based on the finite element method, the steady charge conservation law, Ohm's law, and steady-state Maxwell's equations were solved in order to investigate electric current field, magnetic field, and electromagnetic force (EMF) field. Then, an inhomogeneous multiphase flow model of three phases including bath, metal, and gas bubbles, based on the finite volume method, was implemented using the Euler/Euler approach to investigate melt motion and bath/metal interface fluctuation. EMF was incorporated into the momentum equations of bath and metal as a source term. Additionally, the interphase drag force was employed to consider different phase interactions. Thus, present work owns three main features: (1) magnetohydrodynamic multiphase flow are demonstrated in detail both in aluminum electrolytic cell with traditional cathode and innovative cathode; (2) bath/metal interface fluctuation due to different driving forces of gas bubbles, EMF, and the combined effect of the two driving forces is investigated, which is critical to the energy saving; and (3) the effect of innovative cathode on melt flow and motion of gas bubbles. A good agreement between the predicated results and measurement is obtained. The velocity difference leading to the melt oscillation decreases due to more uniform flow field. The average velocity of metal in the cell with innovative cathode decreases by approximately 33.98 pct. The gas bubbles in the cell with innovative cathode releases more quickly under the effect of protrusion on the cathode. The average bubble release frequency increases from 1.1 to 1.98 Hz. Hence, the voltage drop caused by gas bubbles would decrease significantly. In addition, the two large vortices

  7. Durability and regeneration of activated carbon air-cathodes in long-term operated microbial fuel cells

    Science.gov (United States)

    Zhang, Enren; Wang, Feng; Yu, Qingling; Scott, Keith; Wang, Xu; Diao, Guowang

    2017-08-01

    The performance of activated carbon catalyst in air-cathodes in microbial fuel cells was investigated over one year. A maximum power of 1722 mW m-2 was produced within the initial one-month microbial fuel cell operation. The air-cathodes produced a maximum power >1200 mW m-2 within six months, but gradually became a limiting factor for the power output in prolonged microbial fuel cell operation. The maximum power decreased by 55% when microbial fuel cells were operated over one year due to deterioration in activated carbon air-cathodes. While salt/biofilm removal from cathodes experiencing one-year operation increased a limiting performance enhancement in cathodes, a washing-drying-pressing procedure could restore the cathode performance to its original levels, although the performance restoration was temporary. Durable cathodes could be regenerated by re-pressing activated carbon catalyst, recovered from one year deteriorated air-cathodes, with new gas diffusion layer, resulting in ∼1800 mW m-2 of maximum power production. The present study indicated that activated carbon was an effective catalyst in microbial fuel cell cathodes, and could be recovered for reuse in long-term operated microbial fuel cells by simple methods.

  8. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2002-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves as the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is

  9. Impedance of porous IT-SOFC LSCF:CGO composite cathodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben; Wandel, Marie

    2011-01-01

    performing cathodes showed a slightly suppressed Gerischer impedance, while the impedance spectra of the well performing cathodes showed the presence of an arc due to oxygen gas diffusion. The overall impedance of the well performing cathodes could be described with a slightly suppressed Gerischer impedance......The impedance of technological relevant LSCF:CGO composite IT-SOFC cathodes was studied over a very wide performance range. This was experimentally achieved by impedance measurements on symmetrical cells with three different microstructures in the temperature range 550–850 °C. In order to account...... element in series with a Finite-Length-Warburg (FLW) impedance element. Finally, the origin to a suppression or distortion of the FLG and the Gerischer impedance was discussed and explored in relation to e.g. numerical simulations on the effect of a slightly distributed diffusion length in the FLG, due...

  10. Filters for cathodic arc plasmas

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  11. Barium-Dispenser Thermionic Cathode

    Science.gov (United States)

    Wintucky, Edwin G.; Green, M.; Feinleib, M.

    1989-01-01

    Improved reservoir cathode serves as intense source of electrons required for high-frequency and often high-output-power, linear-beam tubes, for which long operating lifetime important consideration. High emission-current densities obtained through use of emitting surface of relatively-low effective work function and narrow work-function distribution, consisting of coat of W/Os deposited by sputtering. Lower operating temperatures and enhanced electron emission consequently possible.

  12. Bohm velocity in the presence of a hot cathode

    Energy Technology Data Exchange (ETDEWEB)

    Palacio Mizrahi, J. H.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

    2013-08-15

    The spatial distribution of the plasma and beam electrons in a region whose extension from a hot cathode is larger than the Debye length, but smaller than the electron mean free path, is analyzed. In addition, the influence of electrons thermionically emitted from a hot cathode and the ratio of electron-to-ion mass on the Bohm velocity and on the ion and electron densities at the plasma-sheath boundary in a gas discharge are studied. It is shown that thermionic emission has the effect of increasing the Bohm velocity, and this effect is more pronounced for lighter ions. In addition, it is shown that the Bohm velocity cannot be increased to more than 24% above its value when there is no electron emission.

  13. Gadolinia-Doped Ceria Cathodes for Electrolysis of CO2

    Science.gov (United States)

    Adler, Stuart B.

    2009-01-01

    Gadolinia-doped ceria, or GDC, (Gd(0.4)Ce(0.6)O(2-delta), where the value of delta in this material varies, depending on the temperature and oxygen concentration in the atmosphere in which it is being used) has shown promise as a cathode material for high-temperature electrolysis of carbon dioxide in solid oxide electrolysis cells. The polarization resistance of a GDC electrode is significantly less than that of an otherwise equivalent electrode made of any of several other materials that are now in use or under consideration for use as cathodes for reduction of carbon dioxide. In addition, GDC shows no sign of deterioration under typical temperature and gas-mixture operating conditions of a high-temperature electrolyzer. Electrolysis of CO2 is of interest to NASA as a way of generating O2 from the CO2 in the Martian atmosphere. On Earth, a combination of electrolysis of CO2 and electrolysis of H2O might prove useful as a means of generating synthesis gas (syngas) from the exhaust gas of a coal- or natural-gas-fired power plant, thereby reducing the emission of CO2 into the atmosphere. The syngas a mixture of CO and H2 could be used as a raw material in the manufacture, via the Fisher-Tropsch process, of synthetic fuels, lubrication oils, and other hydrocarbon prod

  14. Aging tests of full scale CMS muon cathode strip chambers

    Energy Technology Data Exchange (ETDEWEB)

    D. Acosta et al.

    2003-10-15

    Two CMS production Cathode Strip Chambers were tested for aging effects in the high radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1 m{sup 2} or 700 m of wire in each chamber. The 40% Ar+50%CO{sub 2}+10%CF{sub 4} gas mixture was provided by an open-loop gas system for one of the chambers and by closed-loop recirculating gas system for the other. After accumulating 0.3-0.4 C per centimeter of a wire, which is equivalent to operation during about 30-50 years at the peak LHC luminosity, no significant changes in gas gain, chamber efficiency, and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from {approx}2 nA to {approx}10 nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 G{Omega} to 10-100 G{Omega}. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.

  15. THE METHOD FOR IDENTIFYING THE MOST VULNERABLE AREAS CAUSED BY EXOGENOUS PROCESSES UNDER ARIDIFICATION/HUMIDIFICATION (BASED ON GIS AND RS

    Directory of Open Access Journals (Sweden)

    D. A. Chupina

    2017-01-01

    Full Text Available The paper presents the method of identifying the most vulnerable territories under exogenous processes caused by aridification/humidification. It is based on the assumption that some forms and types of relief increase resistance of terrestrial ecosystems to external influences, while other kinds of relief make them vulnerable. The relationship between landscape and moistening (ground and climatic is of great importance to plains which have groundwater close to the surface. We have used morphometric analysis to divide the territory into hydromorphic and automorphic landscapes. Hydromorphic territories are those that are affected by additional surface moistening and groundwater, while automorphic landscapes are less dependent on groundwater under normal atmospheric moisture. The territory is ranked according to the degree of vulnerability by expert evaluation method. The developed approach is based entirely on using GIS software (ArcGIS 10.2.1 and processing the DEM SRTM. As a result, two models of vulnerability of natural terrestrial ecosystems to exogenic processes on Baraba Plain (Western Siberia have been created for both aridification and humidification cases. The opportunity to estimate the vulnerability is the novel feature for these models of terrestrial ecosystems, in both regional and local scales. The results obtained confirm the existing ideas about the discrete mosaic character of changes in spatial landscape patterns in the area under consideration. For the southern part of Western Siberia where farming is risky the assessment of the potential degree of vulnerability for ecosystems under conditions of increasing climate aridity and extremes is relevant.

  16. Reflective article having a sacrificial cathodic layer

    Science.gov (United States)

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

    2017-09-12

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

  17. Arc initiation in cathodic arc plasma sources

    Science.gov (United States)

    Anders, Andre

    2002-01-01

    A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

  18. Alpha-particle Gas Pressure Gauge

    Science.gov (United States)

    Buehler, M. G.; Bell, L. D.; Hecht, M. H.

    1995-01-01

    Described are preliminary results obtained on a novel gas pressure gauge that operates between 0.1 and 1000 mb. This gauge uses a 1- micron Ci alpha particle source to ionize the gas in a small chamber with an electric field imposed between anode and cathode electrodes that drives positive ions to the cathode where they are collected electronically. This gauge could make Martian pressure measurements.

  19. Gas ion laser construction for electrically isolating the pressure gauge thereof

    Science.gov (United States)

    Wood, C. E.; Witte, R. S. (Inventor)

    1975-01-01

    The valve and the pressure gauge of a gas ion laser were electrically insulated from the laser discharge path by connecting them in series with the cathode of the laser. The laser cathode can be grounded and preferably is a cold cathode although a hot cathode may be used instead. The cold cathode was provided with a central aperture to which was connected both the pressure gauge and the gas pressure reservoir through the valve. This will effectively prevent electric discharges from passing either to the pressure gauge or the valve which would otherwise destroy the pressure gauge.

  20. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

    Science.gov (United States)

    Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

    2015-11-01

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Central tracking chamber with inflated cathode-strip foils

    Energy Technology Data Exchange (ETDEWEB)

    Blackmore, E.W.; Bryman, D.A.; Kuno, Y.; Lim, C.; Numao, T.; Padley, P.; Redlinger, G.; Soluk, R. [TRIUMF, Vancouver, BC (Canada); McPherson, R.A. [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States)

    1998-02-21

    A new cylindrical low-mass central drift chamber has been constructed for the K{sup +}{yields}{pi}{sup +}{nu} anti {nu} experiment at BNL (E787). The chamber consists of twelve layers of axial wire cells and six layers of thin cathode-strip foils, four of which are supported by differential gas pressure. The momentum resolution (RMS) for muons and pions in the range 150-250 MeV/c is found to be about 0.9%. (orig.). 16 refs.

  2. The effect of inhomogeneous compression on water transport in the cathode of a PEM fuel cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

    2011-01-01

    A three-dimensional, multi-component, two-fluid model developed in the commercial CFD package CFX 13 (ANSYS inc.), is used to investigate the effect of porous media compression on transport phenomenon of a PEM Fuel cell (PEMFC). The PEMFC model only consist of the cathode channel, gas diffusion l...

  3. Transport parameters of thin, supported cathode layers in solid oxide fuel cells (SOFCs); Transportparameter duenner, getraegerter Kathodenschichten der oxidkeramischen Brennstoffzelle

    Energy Technology Data Exchange (ETDEWEB)

    Wedershoven, Christian

    2010-12-22

    The aim of this work was to determine the transport properties of thin cathode layers, which are part of the composite layer of a fabricated anode-supported solid oxide fuel cell (SOFC). The transport properties of the anode and cathode have a significant influence on the electrochemical performance of a fuel cell stack and therefore represent an important parameter when designing fuel cell stacks. In order to determine the transport parameters of the cathode layers in a fabricated SOFC, it is necessary to permeate the thin cathode layer deposited on the gas-tight electrolyte with a defined gas transport. These thin cathode layers cannot be fabricated as mechanically stable single layers and cannot therefore be investigated in the diffusion and permeation experiments usually used to determine transport parameters. The setup of these experiments - particularly the sample holder - was therefore altered in this work. The result of this altered setup was a three-dimensional flow configuration. Compared to the conventional setup, it was no longer possible to describe the gas transport in the experiments with an analytical one-dimensional solution. A numerical solution process had to be used to evaluate the measurements. The new setup permitted a sufficiently symmetrical gas distribution and thus allowed the description of the transport to be reduced to a two-dimensional description, which significantly reduced the computational effort required to evaluate the measurements. For pressure-induced transport, a parametrized coherent expression of transport could be derived. This expression is equivalent to the analytical description of the transport in conventional measurement setups, with the exception of parameters that describe the geometry of the gas diffusion. In this case, a numerical process is not necessary for the evaluation. Using the transport parameters of mechanically stable anode substrates, which can be measured both in the old and the new setups, the old and

  4. Sulfonate-immobilized artificial cathode electrolyte interphases layer on Ni-rich cathode

    Science.gov (United States)

    Chae, Bum-Jin; Yim, Taeeun

    2017-08-01

    Although lithium nickel cobalt manganese layered oxides with a high nickel composition have gained great attention due to increased overall energy density for energy conversion/storage systems, poor interfacial stability is considered a critical bottleneck impeding its widespread adoption. We propose a new approach based on immobilizing the artificial cathode-electrolyte interphase layer, which effectively reduces undesired surface reactions, leading to high interfacial stability of cathode material. For installation of artificial cathode-electrolyte interphases, a sulfonate-based amphiphilic organic precursor, which effectively suppresses electrolyte decomposition, is synthesized and subjected to immobilization on cathode material via simple wet-coating, followed by heat treatment at low temperature. The sulfonate-based artificial cathode-electrolyte interphase layer is well-developed on the cathode surface, and the cell controlled by the sulfonate-immobilized cathode exhibits remarkable electrochemical performance, including a high average Coulombic efficiency (99.8%) and cycling retention (97.4%) compared with pristine cathode material. The spectroscopic analyses of the cycled cathode show that the sulfonate-based artificial cathode-electrolyte interphase layer effectively mitigates electrolyte decomposition on the cathode surface, resulting in decreased interfacial resistance between electrode and electrolyte.

  5. ICCP cathodic protection of tanks with photovoltaic power supply

    Directory of Open Access Journals (Sweden)

    Janowski Mirosław

    2016-01-01

    Full Text Available Corrosion is the result of the electrochemical reaction between a metal or composite material usually having conducting current properties. Control of corrosion related defect is a very important problem for structural integrity in ground based structures. Cathodic protection (CP is a technique to protect metallic structures against corrosion in an aqueous environment, it is employed intense on the steel drains in oil and gas industry, specifically to protect underground tanks and pipelines. CP is commonly applied to a coated structure to provide corrosion control to areas where the coating may be damaged. It may be applied to existing structures to prolong their life. There are two types of cathodic protection systems: sacrificial (galvanic anode cathodic protection (SACP; the other system is Impressed Current Cathodic Protection (ICCP. Majority of the structures protected employ impressed current system. The main difference between the two is that SACP uses the galvanic anodes which are electrochemically more electronegative than the structure to be protected - the naturally occurring electrochemical potential difference between different metallic elements to provide protection; ICCP uses an external power source (electrical generator with D.C. with inert anodes, and this system is used for larger structures, or where electrolyte resistivity is high and galvanic anodes cannot economically deliver enough current to provide protection. The essential of CP is based on two parameters, the evolution of the potential and the current of protection. A commonly accepted protection criterion used for steel is a potential value of minus 850 mV. ICCP system consist of anodes connected to a DC power source. As power sources may be used such as solar panels, wind turbines, etc. The object of this study is analysis of the possibilities and operating parameters of ICCP system supplied with photovoltaic solar panels. Photovoltaic generator made up of the

  6. Vacuum arc on the polycrystalline silica cathode

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

    Full Text Available Thin films of silica and its compounds are used in modern technology to produce Li-ion batteries, wear-resistant and protective coatings, thin-films insulators, etc. This coating is produced with CVD methods, with magnetron sputtering systems or with electron-beam evaporation. The vacuum arc evaporation method, presently, is not used.The paper demonstrates a possibility for a long-term operation of vacuum arc evaporator with polycrystalline silica-aluminum alloy (90% of silica cathode and with magnetic system to create a variable form of arch-like magnetic field on the cathode surface. It was shown that archlike configuration of magnetic field provides a stable discharge and uniform cathode spots moving with the velocities up to 5 m/s with magnetic fields induction about 10 mT. Thus, there is no local melting of the cathode, and this provides its long-term work without chips, cracks and destruction. Cathodes spots move over the cathode surface leaving t big craters with melted edges on its surface. The craters size was 150-450μm. The cathode spot movement character and the craters on the cathode surface were like the spots movement, when working on the copper or aluminum cathodes. With the magnetic field induction less than 1 mT, the cathode spots movement was the same as that of on the silica mono-crystal without magnetic field. Thus, the discharge volt-ampere characteristics for different values of magnetic fields were obtained. Voltampere characteristics were increasing and were shifted to the higher voltage with increasing magnetic field. The voltage was 18.7-26.5 V for the arc current 30-140 A.So, it was confirmed that vacuum arc evaporation method could be used for effective evaporation of silica and silica-based alloys and for thin films deposition of this materials.

  7. Gas-Flow Tailoring Fabrication of Graphene-like Co-Nx-C Nanosheet Supported Sub-10 nm PtCo Nanoalloys as Synergistic Catalyst for Air-Cathode Microbial Fuel Cells.

    Science.gov (United States)

    Cao, Chun; Wei, Liling; Zhai, Qiran; Ci, Jiliang; Li, Weiwei; Wang, Gang; Shen, Jianquan

    2017-07-12

    In this work, we presented a novel, facile, and template-free strategy for fabricating graphene-like N-doped carbon as oxygen reduction catalyst in sustainable microbial fuel cells (MFCs) by using an ion-inducing and spontaneous gas-flow tailoring effect from a unique nitrogen-rich polymer gel precursor which has not been reported in materials science. Remarkably, by introduction of trace platinum- and cobalt- precursor in polymer gel, highly dispersed sub-10 nm PtCo nanoalloys can be in situ grown and anchored on graphene-like carbon. The as-prepared catalysts were investigated by a series of physical characterizations, electrochemical measurements, and microbial fuel cell tests. Interestingly, even with a low Pt content (5.13 wt %), the most active Co/N codoped carbon supported PtCo nanoalloys (Co-N-C/Pt) exhibited dramatically improved catalytic activity toward oxygen reduction reaction coupled with superior output power density (1008 ± 43 mW m-2) in MFCs, which was 29.40% higher than the state of the art Pt/C (20 wt %). Notability, the distinct catalytic activity of Co-N-C/Pt was attributed to the highly efficient synergistic catalytic effect of Co-Nx-C and PtCo nanoalloys. Therefore, Co-N-C/Pt should be a promising oxygen reduction catalyst for application in MFCs. Further, the novel strategy for graphene-like carbon also can be widely used in many other energy conversion and storage devices.

  8. Batteries: Overview of Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Doeff, Marca M

    2010-07-12

    The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as

  9. Cathodic oxygen consumption and electrically induced osteogenesis.

    Science.gov (United States)

    Brighton, C T; Adler, S; Black, J; Itada, N; Friedenberg, Z B

    1975-01-01

    Small amounts of electric current stimulate bone formation in the region of a cathode. The purpose of this experiment is to compare changes in oxygen and hydroxyl ion concentration that occur at the cathode at current levels known to be capable of inducing osteogenesis (10-20 muamps) with those changes that occur at current levels known to be toxic to bone (100 muamps). An oxygen consumption chamber containing an oxygen electrode is fitted with two stainless steel electrodes which are connected to a constant current source. At the cathode, with a current of 100 muamps, oxygen is consumed at nearly stoichiometric rates. At higher current (100 muamps) levels, cathodic oxygen consumption gives way to hydrogen evolution. Cathodic hydroxyl ion production is directly proportional to current. It is concluded from these in vitro experiments that at 10-20 muamps the oxygen tension in the vicinity of the cathode is lowered and the pH is moderately increased. At 100 muamps the oxygen tension is not lowered, but the pH is increased dramatically. If these same changes occur in the vicinity of a cathode in vivo, then lowering the local tissue oxygen tension and raising the local pH may be mechanisms operative in electrically induced bone formation.

  10. Minimization of steam requirements and enhancement of water-gas shift reaction with warm gas temperature CO2 removal

    Science.gov (United States)

    Siriwardane, Ranjani V; Fisher, II, James C

    2013-12-31

    The disclosure utilizes a hydroxide sorbent for humidification and CO.sub.2 removal from a gaseous stream comprised of CO and CO.sub.2 prior to entry into a water-gas-shift reactor, in order to decrease CO.sub.2 concentration and increase H.sub.2O concentration and shift the water-gas shift reaction toward the forward reaction products CO.sub.2 and H.sub.2. The hydroxide sorbent may be utilized for absorbtion of CO.sub.2 exiting the water-gas shift reactor, producing an enriched H.sub.2 stream. The disclosure further provides for regeneration of the hydroxide sorbent at temperature approximating water-gas shift conditions, and for utilizing H.sub.2O product liberated as a result of the CO.sub.2 absorption.

  11. Optimization of the Interconnect Ribs for a Cathode-Supported Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Wei Kong

    2014-01-01

    Full Text Available A comprehensive mathematical model of the performance of the cathode-supported solid oxide fuel cell (SOFC with syngas fuel is presented. The model couples the intricate interdependency between the ionic conduction, electronic conduction, gas transport, the electrochemical reaction processes in the functional layers and on the electrode/electrolyte interfaces, methane steam reforming (MSR and the water gas shift reaction (WGSR. The validity of the mathematical model is demonstrated by the excellent agreement between the numerical and experimental I-V curves. The effect of anode rib width and cathode rib width on gas diffusion and cell performance is examined. The results show conclusively that the cell performance is strongly influenced by the rib width. Furthermore, the anode optimal rib width is smaller than that for cathode, which is contrary to anode-supported SOFC. Finally, the formulae for the anode and cathode optimal rib width are given, which provide an easy to use guidance for the broad SOFC engineering community.

  12. Design Of Photovoltaic Powered Cathodic Protection System

    Directory of Open Access Journals (Sweden)

    Golina Samir Adly

    2017-07-01

    Full Text Available The corrosion caused by chemical reaction between metallic structures and surrounding mediums such as soil or water .the CP cathodic protection system is used to protect metallic structure against corrosion. Cathodic protection CP used to minimize corrosion by utilizing an external source of electrical current which forces the entire structure to become a cathode. There are two Types of cathodic protection system Galvanic current Impressed current.the Galvanic current is called a sacrificial anode is connected to the protected structure cathode through a DC power supply. In Galvanic current system a current passes from the sacrificing anode to the protected structure .the sacrificial anode is corroded rather than causing the protected structure corrosion .protected structure requires a constant current to stop the corrosion which determined by area structure metal and the surrounding medium. The rains humidity are decrease soil resistivity and increase the DC current .The corrosion and over protection resulting from increase in the DC current is harmful for the metallic structure. This problem can be solved by conventional cathodic protection system by manual adjustment of DC voltage periodically to obtain a constant current .the manual adjustment of DC voltage depends on experience of the technician and using the accuracy of the measuring equipment. The errors of measuring current depend on error from the technician or error from the measuring equipment. the corrosion of structure may occur when the interval between two successive adjustment is long .An automatically regulated cathodic protection system is used to overcome problems from conventional cathodic protection system .the regulated cathodic protection system adjust the DC voltage of the system automatically when it senses the variations of surrounding medium resistivity so the DC current is constant at the required level.

  13. Cells having cathodes containing polycarbon disulfide materials

    Science.gov (United States)

    Okamoto, Yoshi; Skotheim, Terje A.; Lee, Hung S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS.sub.x).sub.n, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode.

  14. Cells having cathodes containing polycarbon disulfide materials

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Y.; Skotheim, T.A.; Lee, H.S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS{sub x}){sub n}, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode. 5 figs.

  15. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Cathodic protection... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each cathodic protection system required by this subpart must provide a level of cathodic protection that complies with one...

  16. Novel Composite Materials for SOFC Cathode-Interconnect Contact

    Energy Technology Data Exchange (ETDEWEB)

    J. H. Zhu

    2009-07-31

    This report summarized the research efforts and major conclusions of our University Coal Research Project, which focused on developing a new class of electrically-conductive, Cr-blocking, damage-tolerant Ag-perovksite composite materials for the cathode-interconnect contact of intermediate-temperature solid oxide fuel cell (SOFC) stacks. The Ag evaporation rate increased linearly with air flow rate initially and became constant for the air flow rate {ge} {approx} 1.0 cm {center_dot} s{sup -1}. An activation energy of 280 KJ.mol{sup -1} was obtained for Ag evaporation in both air and Ar+5%H{sub 2}+3%H{sub 2}O. The exposure environment had no measurable influence on the Ag evaporation rate as well as its dependence on the gas flow rate, while different surface morphological features were developed after thermal exposure in the oxidizing and reducing environments. Pure Ag is too volatile at the SOFC operating temperature and its evaporation rate needs to be reduced to facilitate its application as the cathode-interconnect contact. Based on extensive evaporation testing, it was found that none of the alloying additions reduced the evaporation rate of Ag over the long-term exposure, except the noble metals Au, Pt, and Pd; however, these noble elements are too expensive to justify their practical use in contact materials. Furthermore, the addition of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM) into Ag to form a composite material also did not significantly modify the Ag evaporation rate. The Ag-perovskite composites with the perovskite being either (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.8}Fe{sub 0.2})O{sub 3} (LSCF) or LSM were systematically evaluated as the contact material between the ferritic interconnect alloy Crofer 22 APU and the LSM cathode. The area specific resistances (ASRs) of the test specimens were shown to be highly dependent on the volume percentage and the type of the perovskite present in the composite contact material as well as the amount of thermal cycling

  17. Microstructure-scaled active sites imaging of a solid oxide fuel cell composite cathode

    Science.gov (United States)

    Nagasawa, Tsuyoshi; Hanamura, Katsunori

    2017-11-01

    Active sites for oxygen reduction reaction in strontium-doped lanthanum manganite (LSM)/scandia-stabilized zirconia (ScSZ) composite cathode of solid oxide fuel cell (SOFC) is visualized in microstructure scale by oxygen isotope labeling. In order to quench a reaction, a SOFC power generation equipment with a nozzle for direct helium gas impinging jet to the cell is prepared. A typical electrolyte-supported cell is operated by supplying 18O2 at 1073 K and abruptly quenched to room temperature. During the quench, the temperature of the cell is decreased from 1073 K to 673 K in 1 s. The 18O concentration distribution in the cross section of the quenched cathode is obtained by secondary ion mass spectrometry (SIMS) with a spatial resolution of 50 nm. The obtained 18O mapping gives the first visualization of highly distributed active sites in the composite cathode both in macroscopic and particle scales.

  18. Low-energy plasma-cathode electron gun with a perforated emission electrode

    Science.gov (United States)

    Burdovitsin, Victor; Kazakov, Andrey; Medovnik, Alexander; Oks, Efim; Tyunkov, Andrey

    2017-11-01

    We describe research of influence of the geometric parameters of perforated electrode on emission parameters of a plasma cathode electron gun generating continuous electron beams at gas pressure 5-6 Pa. It is shown, that the emission current increases with increasing the hole diameters and decreasing the thickness of the perforated emission electrode. Plasma-cathode gun with perforated electron can provide electron extraction with an efficiency of up to 72 %. It is shown, that the current-voltage characteristic of the electron gun with a perforated emission electrode differs from that of similar guns with fine mesh grid electrode. The plasma-cathode electron gun with perforated emission electrode is used for electron beam welding and sintering.

  19. Microstructural studies on degradation of interface between LSM–YSZ cathode and YSZ electrolyte in SOFCs

    DEFF Research Database (Denmark)

    Liu, Yi-Lin; Hagen, Anke; Barfod, Rasmus

    2009-01-01

    The changes in the cathode/electrolyte interface microstructure have been studied on anode-supported technological solid oxide fuel cells (SOFCs) that were subjected to long-term (1500 h) testing at 750 °C under high electrical loading (a current density of 0.75 A/cm2). These cells exhibit...... different cathode degradation rates depending on, among others, the composition of the cathode gas, being significantly smaller in oxygen than in air. FE-SEM and high resolution analytical TEM were applied for characterization of the interface on a submicron- and nano-scale. The interface degradation has...... that in the cell tested in air this mechanism contributes to an estimated overall reduction in the LSM coverage and the TPB length by 50 and 30%, respectively. For the cell tested in oxygen the corresponding values are 10 and 4%. Secondly, in the cell tested in air the LSM coverage and the TPB length appear...

  20. The use of stainless steel and nickel alloys as low-cost cathodes in microbial electrolysis cells

    KAUST Repository

    Selembo, Priscilla A.

    2009-05-01

    Microbial electrolysis cells (MECs) are used to produce hydrogen gas from the current generated by bacteria, but low-cost alternatives are needed to typical cathode materials (carbon cloth, platinum and Nafion™). Stainless steel A286 was superior to platinum sheet metal in terms of cathodic hydrogen recovery (61% vs. 47%), overall energy recovery (46% vs. 35%), and maximum volumetric hydrogen production rate (1.5 m3 m-3 day-1 vs. 0.68 m3 m-3 day-1) at an applied voltage of 0.9 V. Nickel 625 was better than other nickel alloys, but it did not perform as well as SS A625. The relative ranking of these materials in MEC tests was in agreement with cyclic voltammetry studies. Performance of the stainless steel and nickel cathodes was further increased, even at a lower applied voltage (0.6 V), by electrodepositing a nickel oxide layer onto the sheet metal (cathodic hydrogen recovery, 52%, overall energy recovery, 48%; maximum volumetric hydrogen production rate, 0.76 m3 m-3 day-1). However, performance of the nickel oxide cathodes decreased over time due to a reduction in mechanical stability of the oxides (based on SEM-EDS analysis). These results demonstrate that non-precious metal cathodes can be used in MECs to achieve hydrogen gas production rates better than those obtained with platinum. © 2009 Elsevier B.V. All rights reserved.

  1. Conversion of Carbon Dioxide to Ethanol by Electrochemical Synthesis Method Using Brass as A Cathode

    Directory of Open Access Journals (Sweden)

    Septian Ramadan

    2017-09-01

    Full Text Available The effect of potential and gas flow rate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide to ethanol. The conversion process is carried out using a NaHCO3 electrolyte solution in an electrochemical reactor equipped with a cathode and anode. As cathode is used brass, while as anode is used carbon. The result of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced qualitatively and quantitatively. The optimum electrochemical synthesis conditions to convert carbon dioxide to ethanol are potential and gas flow rate are 3 volts and 0.5 L/minutes with ethanol concentration yielded 1.32%.

  2. Reservoir Scandate Cathode for Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to combine two revolutionary cathode technologies into a single device for use in electric space propulsion. This will overcome problems that both...

  3. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith...elements on the kinetics of oxygen reduction reaction catalyzed on titanium oxide in order to develop new approaches for controlling galvanic corrosion

  4. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2003-03-31

    This report represents a summary of the work carried out on this project which started October 1999 and ended March 2003. A list of the publications resulting from the work are contained in Appendix A. The most significant achievements are: (1) Dense nanocrystalline zirconia and ceria films were obtained at temperatures < 400 C. (2) Nanocrystalline films of both ceria and zirconia were characterized. (3) We showed that under anodic conditions 0.5 to 1 micron thick nanocrystalline films of Sc doped zirconia have sufficient electronic conductivity to prevent them from being useful as an electrolyte. (4) We have developed a process by which dense 0.5 to 5 micron thick dense films of either YSZ or ceria can be deposited on sintered porous substrates which serve as either the cathode or anode at temperatures as low as 400 C. (5) The program has provided the research to produce two PhD thesis for students, one is now working in the solid oxide fuel cell field. (6) The results of the research have resulted in 69 papers published, 3 papers submitted or being prepared for publication, 50 oral presentations and 3 patent disclosures.

  5. Outgassing rate analysis of a velvet cathode and a carbon fiber cathode

    Science.gov (United States)

    Li, An-Kun; Fan, Yu-Wei; Qian, Bao-Liang; Zhang, Zi-cheng; Xun, Tao

    2017-11-01

    In this paper, the outgassing-rates of a carbon fiber array cathode and a polymer velvet cathode are tested and discussed. Two different methods of measurements are used in the experiments. In one scheme, a method based on dynamic equilibrium of pressure is used. Namely, the cathode works in the repetitive mode in a vacuum diode, a dynamic equilibrium pressure would be reached when the outgassing capacity in the chamber equals the pumping capacity of the pump, and the outgassing rate could be figured out according to this equilibrium pressure. In another scheme, a method based on static equilibrium of pressure is used. Namely, the cathode works in a closed vacuum chamber (a hard tube), and the outgassing rate could be calculated from the pressure difference between the pressure in the chamber before and after the work of the cathode. The outgassing rate is analyzed from the real time pressure evolution data which are measured using a magnetron gauge in both schemes. The outgassing rates of the carbon fiber array cathode and the velvet cathode are 7.3 ± 0.4 neutrals/electron and 85 ± 5 neutrals/electron in the first scheme and 9 ± 0.5 neutrals/electron and 98 ± 7 neutrals/electron in the second scheme. Both the results of two schemes show that the outgassing rate of the carbon fiber array cathode is an order smaller than that of the velvet cathode under similar conditions, which shows that this carbon fiber array cathode is a promising replacement of the velvet cathode in the application of magnetically insulated transmission line oscillators and relativistic magnetrons.

  6. Plasma-Surface Interactions in Hollow Cathode Discharges for Electric Propulsion

    Science.gov (United States)

    Capece, Angela Maria

    Electric thrusters generate high exhaust velocities and can achieve specific impulses in excess of 1000 s. The low thrust generation and high specific impulse make electric propulsion ideal for interplanetary missions, spacecraft station keeping, and orbit raising maneuvers. Consequently, these devices have been used on a variety of space missions including Deep Space 1, Dawn, and hundreds of commercial spacecraft in Earth orbit. In order to provide the required total impulses, thruster burn time can often exceed 10,000 hours, making thruster lifetime essential. One of the main life-limiting components on ion engines is the hollow cathode, which serves as the electron source for ionization of the xenon propellant gas. Reactive contaminants such as oxygen can modify the cathode surface morphology and degrade the electron emission properties. Hollow cathodes that operate with reactive impurities in the propellant will experience higher operating temperatures, which increase evaporation of the emission materials and reduce cathode life. A deeper understanding of the mechanisms initiating cathode failure will improve thruster operation, increase lifetime, and ultimately reduce cost. A significant amount of work has been done previously to understand the effects of oxygen poisoning on vacuum cathodes; however, the xenon plasma adds complexity, and its role during cathode poisoning is not completely understood. The work presented here represents the first attempt at understanding how oxygen impurities in the xenon discharge plasma alter the emitter surface and affect operation of a 4:1:1 BaO-CaO-Al2O3 hollow cathode. A combination of experimentation and modeling was used to investigate how oxygen impurities in the discharge plasma alter the emitter surface and reduce the electron emission capability. The experimental effort involved operating a 4:1:1 hollow cathode at various conditions with oxygen impurities in the xenon flow. Since direct measurements of the emitter

  7. Lanthanum manganate based cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Juhl Joergensen, M.

    2001-07-01

    Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained a composite layer made from lanthanum strontium manganate (LSM) and yttria stabilised zirconia (YSZ) and a layer of pure LSM aimed for current collection. The performance of the composite electrodes was sensitive to microstructure and thickness. Further, the interface between the composite and the current collecting layer proved to affect the performance. In a durability study severe deg-radation of the composite electrodes was found when passing current through the electrode for 2000 hours at 1000 deg. C. This was ascribed to pore formation along the composite interfaces and densification of the composite and current collector microstructure. An evaluation of the measurement approach indicated that impedance spectroscopy is a very sensitive method. This affects the reproducibility, as small undesirable variations in for instance the microstructure from electrode to electrode may change the impedance. At least five processes were found to affect the impedance of LSM/YSZ composite electrodes. Two high frequency processes were ascribed to transport of oxide ions/oxygen intermediates across LSM/YSZ interfaces and through YSZ in the composite. Several competitive elementary reaction steps, which appear as one medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple phase boundary between electrode, electrolyte and gas phase, was found. (au)

  8. Gas block mechanism for water removal in fuel cells

    Science.gov (United States)

    Issacci, Farrokh; Rehg, Timothy J.

    2004-02-03

    The present invention is directed to apparatus and method for cathode-side disposal of water in an electrochemical fuel cell. There is a cathode plate. Within a surface of the plate is a flow field comprised of interdigitated channels. During operation of the fuel cell, cathode gas flows by convection through a gas diffusion layer above the flow field. Positioned at points adjacent to the flow field are one or more porous gas block mediums that have pores sized such that water is sipped off to the outside of the flow field by capillary flow and cathode gas is blocked from flowing through the medium. On the other surface of the plate is a channel in fluid communication with each porous gas block mediums. The method for water disposal in a fuel cell comprises installing the cathode plate assemblies at the cathode sides of the stack of fuel cells and manifolding the single water channel of each of the cathode plate assemblies to the coolant flow that feeds coolant plates in the stack.

  9. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  10. High temperature electrolyte supported Ni-GDC/YSZ/LSM SOFC operation on two-stage Viking gasifier product gas

    DEFF Research Database (Denmark)

    Hofmann, P.; Schweiger, A.; Fryda, L.

    2007-01-01

    and tar traces. The chosen SOFC was electrolyte supported with a nickel/gadolinium-doped cerium oxide (Ni-GDC) anode, known for its carbon deposition resistance. Through humidification the steam to carbon ratio (S/C) was adjusted to 0.5, which results in a thermodynamically carbon free condition......This paper presents the results from a 150 h test of a commercial high temperature single planar solid oxide fuel cell (SOFC) operating on wood gas from the Viking two-stage fixed-bed downdraft gasifier, which produces an almost tar-free gas, that was further cleaned for particulates, sulphur...

  11. A High Capacity Li-Ion Cathode: The Fe(III/VI Super-Iron Cathode

    Directory of Open Access Journals (Sweden)

    Stuart Licht

    2010-05-01

    Full Text Available A super-iron Li-ion cathode with a 3-fold higher reversible capacity (a storage capacity of 485 mAh/g is presented. One of the principle constraints to vehicle electrification is that the Li-ion cathode battery chemistry is massive, and expensive. Demonstrated is a 3 electron storage lithium cathodic chemistry, and a reversible Li super-iron battery, which has a significantly higher capacity than contemporary Li-ion batteries. The super-iron Li-ion cathode consists of the hexavalent iron (Fe(VI salt, Na2FeO4, and is formed from inexpensive and clean materials. The charge storage mechanism is fundamentally different from those of traditional lithium ion intercalation cathodes. Instead, charge storage is based on multi-electron faradaic reduction, which considerably enhances the intrinsic charge storage capacity.

  12. Generation and delivery device for ozone gas

    Science.gov (United States)

    Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

    2002-01-01

    The present invention provides an ozone generation and delivery system that lends itself to small scale applications and requires very low maintenance. The system preferably includes an anode reservoir and a cathode phase separator each having a hydrophobic membrane to allow phase separation of produced gases from water. The hydrogen gas, ozone gas and water containing ozone may be delivered under pressure.

  13. Orbitron-type vacuum gauge with nanocarbon field cathode

    Directory of Open Access Journals (Sweden)

    Alexander V. Arkhipov

    2015-03-01

    Full Text Available A novel electron–optical scheme of ionization-type vacuum gauge is proposed that allows the use of field-emission nanocarbon cathodes. The developed gauge satisfies the requirements imposed by possible utilization in on-board satellite equipment: low mass, size and energy consumption, low turn-on time, etc. High efficiency and sensitivity of the sensor are achieved by the use of an electrostatic trap for accumulation of electrons ionizing the gas molecules. Magnetic field was not used for mass economy reason and to avoid possible influence onto other on-board equipment. The main problem solved in the work originated from the intrinsic contradiction between the aims of achieving long-term confinement of electrons in the trap and focusing of the applied electric field at the cathode, the latter being necessary to utilize the phenomenon of field-induced emission. Experimental tests were performed with two prototype devices realizing different versions the electron-scheme design, viability of both developed schemes has been confirmed.

  14. High power gas laser amplifier

    Science.gov (United States)

    Leland, Wallace T.; Stratton, Thomas F.

    1981-01-01

    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  15. The influence of cathode excavation of cathodic arc evaporator on thickness uniformity and erosion products angle distribution

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

    Full Text Available Cathodic arc evaporators are used for coating with functional films. Prolonged or buttend evaporators may be used for this purposes. In butt-end evaporator the cathode spots move continuously on the cathode work surface and evaporate cathode material. High depth excavation profile forms on the cathode work surface while the thick coating precipitation (tens or hundreds of microns. The cathode excavation profile is shaped like a “cup” with high walls for electrostatic discharge stabilization systems with axial magnetic fields. Cathode spots move on the bottom of the “cup”. It is very likely that high “cup” walls are formed as a result of lasting work time influence on the uniformity of precipitated films.In the present work the influence of excavation profile walls height on the uniformity of precipitated coating was carried out. The high profile walls are formed due to lasting work of DC vacuum arc evaporator. The cathode material used for tests was 3003 aluminum alloy. The extended substrate was placed parallel to the cathode work surface. Thickness distribution along the substrate length with the new cathode was obtained after 6 hours and after 12 hours of continuous operation.The thickness distribution of precipitated coating showed that the cathode excavation has an influence on the angular distribution of the matter escaping the cathode. It can be clearly seen from the normalized dependence coating thickness vs the distance from the substrate center. Also the angular distribution of the matter flow from the cathode depending on the cathode working time was obtained. It was shown that matter flow from the cathode differs from the LambertKnudsen law. The more the cathode excavation the more this difference.So, cathode excavation profile has an influence on the uniformity of precipitated coating and it is necessary to take in account the cathode excavation profile while coating the thick films.

  16. Synchrotron Investigations of SOFC Cathode Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  17. Cathode architectures for alkali metal / oxygen batteries

    Science.gov (United States)

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  18. Process For Patterning Dispenser-Cathode Surfaces

    Science.gov (United States)

    Garner, Charles E.; Deininger, William D.

    1989-01-01

    Several microfabrication techniques combined into process cutting slots 100 micrometer long and 1 to 5 micrometer wide into tungsten dispenser cathodes for traveling-wave tubes. Patterned photoresist serves as mask for etching underlying aluminum. Chemically-assisted ion-beam etching with chlorine removes exposed parts of aluminum layer. Etching with fluorine or chlorine trifluoride removes tungsten not masked by aluminum layer. Slots enable more-uniform low-work function coating dispensed to electron-emitting surface. Emission of electrons therefore becomes more uniform over cathode surface.

  19. Klystron Amplifier Utilizing Scandate Cathode and Electrostatic Focusing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build an electrostatically focused klystron that exploits recent breakthroughs in scandate cathode technology. We have built cathodes with greater than...

  20. Long Life Cold Cathodes for Hall effect Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An electron source incorporating long life, high current density cold cathodes inside a microchannel plate for use with ion thrusters is proposed. Cathode lifetime...

  1. Nano-Particle Scandate Cathode for Space Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an improved cathode based on our novel theory of the role of scandium oxide in enhancing emission in tungsten impregnate cathodes. Recent results have...

  2. Comparison of Nonprecious Metal Cathode Materials for Methane Production by Electromethanogenesis.

    KAUST Repository

    Siegert, Michael

    2014-02-18

    In methanogenic microbial electrolysis cells (MMCs), CO2 is reduced to methane using a methanogenic biofilm on the cathode by either direct electron transfer or evolved hydrogen. To optimize methane generation, we examined several cathode materials: plain graphite blocks, graphite blocks coated with carbon black or carbon black containing metals (platinum, stainless steel or nickel) or insoluble minerals (ferrihydrite, magnetite, iron sulfide, or molybdenum disulfide), and carbon fiber brushes. Assuming a stoichiometric ratio of hydrogen (abiotic):methane (biotic) of 4:1, methane production with platinum could be explained solely by hydrogen production. For most other materials, however, abiotic hydrogen production rates were insufficient to explain methane production. At -600 mV, platinum on carbon black had the highest abiotic hydrogen gas formation rate (1600 ± 200 nmol cm(-3) d(-1)) and the highest biotic methane production rate (250 ± 90 nmol cm(-3) d(-1)). At -550 mV, plain graphite (76 nmol cm(-3) d(-1)) performed similarly to platinum (73 nmol cm(-3) d(-1)). Coulombic recoveries, based on the measured current and evolved gas, were initially greater than 100% for all materials except platinum, suggesting that cathodic corrosion also contributed to electromethanogenic gas production.

  3. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

    . However, they have the potential of being useful as an interface on the anode side of the electrolyte. NexTech has focused much of its effort during the past few months on establishing tape casting methods for porous LSM substrates. This work, performed under a separate DOE-funded program, involved tape casting formulations comprising LSM powders with bi-modal particle size distributions and fugitive pore forming additives. Sintered LSM substrates with porosities in the 30 to 40 vol% range, and pore sizes of 10 {approx} 20 microns have been prepared. In addition, tape casting formulations involving composite mixtures of LSM and Sm-doped ceria (SDC) have been evaluated. The LSM/SDC cathode substrates are expected to provide better performance at low temperatures. Characterization of these materials is currently underway.

  4. OPTIMIZATION OF THE CATHODE LONG-TERM STABILITY IN MOLTEN CARBONATE FUEL CELLS: EXPERIMENTAL STUDY AND MATHEMATICAL MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ralph E. White

    2000-09-30

    The dissolution of NiO cathodes during cell operation is a limiting factor to the successful commercialization of molten carbonate fuel cells (MCFCs). Microencapsulation of the NiO cathode has been adopted as a surface modification technique to increase the stability of NiO cathodes in the carbonate melt. The material used for surface modification should possess thermodynamic stability in the molten carbonate and also should be electro catalytically active for MCFC reactions. A simple first principles model was developed to understand the influence of exchange current density and conductivity of the electrode material on the polarization of MCFC cathodes. The model predictions suggest that cobalt can be used to improve the corrosion resistance of NiO cathode without affecting its performance. Cobalt was deposited on NiO cathode by electroless deposition. The morphology and thermal oxidation behavior of Co coated NiO was studied using scanning electron microscopy and thermal gravimetric analysis respectively. The electrochemical performance of cobalt encapsulated NiO cathodes were investigated with open circuit potential measurement and current-potential polarization studies. These results were compared to that of bare NiO. The electrochemical oxidation behavior of cobalt-coated electrodes is similar to that of the bare NiO cathode. Dissolution of nickel into the molten carbonate melt was less in case of cobalt encapsulated nickel cathodes. Co coated on the surface prevents the dissolution of Ni in the melt and thereby stabilizes the cathode. Finally, cobalt coated nickel shows similar polarization characteristics as nickel oxide. A similar surface modification technique has been used to improve the performance of the SS 304 current collectors used in MCFC cells. SS 304 was encapsulated with nanostructured layers of NiCo and NiMo by electroless deposition. The corrosion behavior of bare and surface modified SS 304 in molten carbonate under cathode gas atmosphere was

  5. Erosion of a copper cathode in a negative corona discharge

    Science.gov (United States)

    Asinovskiĭ, É. I.; Petrov, A. A.; Samoylov, I. S.

    2008-02-01

    The pulsed-periodic regime of a negative corona (Trichel pulses) in atmospheric-pressure air, which leads to explosion emission mechanisms (ecton generation) of pointed cathode erosion, is investigated. The jet erosion process at the copper cathode is discovered, and micrometer dendritelike structures formed by erosion products returning to the cathode are detected.

  6. A Transient Model for Fuel Cell Cathode-Water Propagation Behavior inside a Cathode after a Step Potential

    National Research Council Canada - National Science Library

    Der-Sheng Chan; Kan-Lin Hsueh

    2010-01-01

      Most of the voltage losses of proton exchange membrane fuel cells (PEMFC) are due to the sluggish kinetics of oxygen reduction on the cathode and the low oxygen diffusion rate inside the flooded cathode...

  7. Transport of Ice into the Stratosphere and the Humidification of the Stratosphere over the 21st Century

    Science.gov (United States)

    Dessler, A. E.; Ye, H.; Wang, T.; Schoeberl, M. R.; Oman, L. D.; Douglass, A. R.; Butler, A. H.; Rosenlof, K. H.; Davis, S. M.; Portmann, R. W.

    2016-01-01

    Climate models predict that tropical lower-stratospheric humidity will increase as the climate warms. We examine this trend in two state-of-the-art chemistry-climate models. Under high greenhouse gas emissions scenarios, the stratospheric entry value of water vapor increases by approx. 1 part per million by volume (ppmv) over this century in both models. We show with trajectory runs driven by model meteorological fields that the warming tropical tropopause layer (TTL) explains 50-80% of this increase. The remainder is a consequence of trends in evaporation of ice convectively lofted into the TTL and lower stratosphere. Our results further show that, within the models we examined, ice lofting is primarily important on long time scales - on interannual time scales, TTL temperature variations explain most of the variations in lower stratospheric humidity. Assessing the ability of models to realistically represent ice-lofting processes should be a high priority in the modeling community.

  8. A multi-use cathode cell MWPC

    CERN Document Server

    Delpierre, P A; Bonierbal, P; Diop, A; Espigat, P; Herteault, L; Jobez, J P; Saget, G; Saigne, R; Sotiras, D; Turlot, J P; Vassent, M

    1982-01-01

    Describes a highly flexible modular design for multiwire proportional chambers used in the CERN-NA3 experiment. The authors illustrate this flexibility by describing the transformation of one chamber into a cathode-cell shower detector and giving its performance as such.

  9. Close cathode chamber: Low material budget MWPC

    Science.gov (United States)

    Varga, Dezső; Kiss, Gábor; Hamar, Gergő; Bencédi, Gyula

    2013-01-01

    Performance of asymmetric-type MWPC-s are presented. In this structure, referred to as Close Cathode Chamber in an earlier study, the material budget is significantly reduced on one hand by the elimination of external support frame, on the other hand by thin detector walls. In this paper it is demonstrated that the outline is compatible with large size detectors (1 m wire length), maintaining mechanical and operation stability, with total weight of 3 kg (including support structure) for a half square meter surface. The detection efficiency and response time is shown to be sufficient for L0 triggering in the ALICE VHMPID layout. Reduced sensitivity to cathode deformations (due to internal overpressure as mechanical strain) is directly demonstrated. On small sized chambers, improvement of position resolution with analog readout is evaluated, reaching 0.09 mm RMS with 2 mm wide cathode segments. Simulation results on signal time evolutions are presented. With the above studies, comparison of classical MWPC-s and the Close Cathode Chamber design is performed in all major aspects.

  10. pipelines cathodic protection design methodologies for impressed ...

    African Journals Online (AJOL)

    HOD

    total external surface area of 226224m2. The computation further showed the current requirement was attainable with connection of 3620 anodes to set up a natural potential between sacrificial anode and pipeline. Key words: Cathodic protection, corrosion, impressed current, pipeline, sacrificial anodes. 1. INTRODUCTION.

  11. Pipelines cathodic protection design methodologies for impressed ...

    African Journals Online (AJOL)

    ... X42 pipeline with total external surface area of 226224m2. The computation further showed the current requirement was attainable with connection of 3620 anodes to set up a natural potential between sacrificial anode and pipeline. Keywords: Cathodic protection, corrosion, impressed current, pipeline, sacrificial anodes ...

  12. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

    . The full cells had a Ni-YSZ anode and anode support, a thin YSZ electrolyte, and a CGO barrier layer. The symmetric and full cell cathode responses were compared at open-circuit voltage. Humidified hydrogen was used as the fuel in the full cell measurements. Differential analysis of the impedance data...

  13. Adsorptive Cathodic Stripping Voltammetric Determination of ...

    African Journals Online (AJOL)

    Purpose: To investigate the electro-reduction behaviour and determination of ciprofloxacin using a hanging mercury drop electrode. Methods: Cyclic voltammograms of ciprofloxacin recorded in Britton – Robinson buffers pH 2 – 5 exhibit a single irreversible cathodic peak. The dependence of the peak current and peak ...

  14. Poisoning and reactivation processes in oxide-type cathodes: Part I. Polycrystalline mixed oxides

    Science.gov (United States)

    Shih, A.; Haas, G. A.

    A study has been made of the poisoning and reactivation characteristics of alkaline earth oxide-type cathodes after extended periods of shelf storage. Both emitted and incident electrons were used to measure changes in the electronics properties, i.e. work function. The variations in work function over the surface were obtained in both distribution form as well as topographic presentation using a scanning low energy electron probe (SLEEP). These measurements were correlated with simultaneously occurring compositional changes using Auger, gas desorption and ion scattering techniques. Measurements were made on realistic cathodes in actual vacuum tube ambients. The results showed that oxide-type cathodes poison within a few hours after shut-down by the adsorption of residual gases contained in the vacuum ambient. (The effects of CO 2 were specifically demonstrated.) These adsorbates are, however, desorbed upon heating and in combination with other reactivation processes (such as formation of surface Ba layers when using reducing substrates), the cathode can reach full activation again by the time the temperature reaches the normal operating temperature. The poisoning and reactivation phenomena are a combination of a number of simultaneous processes, and studies to separate and identify these is the objective of part II of this paper.

  15. A rechargeable lithium-oxygen battery with dual mediators stabilizing the carbon cathode

    Science.gov (United States)

    Gao, Xiangwen; Chen, Yuhui; Johnson, Lee R.; Jovanov, Zarko P.; Bruce, Peter G.

    2017-09-01

    At the cathode of a Li-O2 battery, O2 is reduced to Li2O2 on discharge, the process being reversed on charge. Li2O2 is an insulating and insoluble solid, leading ultimately to low rates, low capacities and early cell death if formed on the cathode surface. Here we show that when using dual mediators, 2,5-Di-tert-butyl-1,4-benzoquinone [DBBQ] on discharge and 2,2,6,6-tetramethyl-1-piperidinyloxy [TEMPO] on charge, the electrochemistry at the cathode surface is decoupled from Li2O2 formation/decomposition in solution. Capacities of 2 mAh cmareal-2 at 1 mA cmareal-2 with low polarization on charge/discharge are demonstrated, and up to 40 mAh cmareal-2 at rates ≫1 mA cmareal-2 are anticipated if suitable gas diffusion electrodes can be devised. One of the major barriers to the progress of Li-O2 cells is decomposition of the carbon cathode. By forming/decomposing Li2O2 in solution and avoiding high charge potentials, the carbon instability is significantly mitigated (<0.008% decomposition per cycle compared with 0.12% without mediators).

  16. Experimental Study on Improvement of Performance by Wave Form Cathode Channels in a PEM Fuel Cell

    Directory of Open Access Journals (Sweden)

    Sun-Joon Byun

    2018-02-01

    Full Text Available We propose a wave-like design on the surface of cathode channels (wave form cathode channels to improve oxidant delivery to gas diffusion layers (GDLs. We performed experiments using proton-exchange membrane fuel cells (PEMFCs combined with wave form surface design on cathodes. We varied the factors of the distance between wave-bumps (the adhesive distance, AD, and the size of the wave-bumps (the expansion ratio, ER. The ADs are three, four, and five times the size of the half-circle bump’s radius, and the ERs are two-thirds, one-half, and one-third of the channel’s height. We evaluated the performances of the fuel cells, and compared the current-voltage (I-V relations. For comparison, we prepared PEMFCs with conventional flat-surfaced oxygen channels. Our aim in this work is to identify fuel cell operation by modifying the surface design of channels, and ultimately to find the optimal design of cathode channels that will maximize fuel cell performance.

  17. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  18. The competition between cathodic oxygen and ozone reduction and its role in dictating the reaction mechanisms of an electro-peroxone process.

    Science.gov (United States)

    Xia, Guangsen; Wang, Yujue; Wang, Bin; Huang, Jun; Deng, Shubo; Yu, Gang

    2017-07-01

    Previous studies indicate that effective generation of hydrogen peroxide (H2O2) from cathodic oxygen (O2) reduction is critical for the improved water treatment performance (e.g., enhanced pollutant degradation and reduced bromate formation) during the electro-peroxone (E-peroxone) process (a combined process of electrolysis and ozonation). However, undesired reactions (e.g., O3, H2O2, and H2O reductions) may occur in competition with O2 reduction at the cathode. To get a better understanding of how these side reactions would affect the process, this study investigated the cathodic reaction mechanisms during electrolysis with O2/O3 gas mixture sparging using various electrochemical techniques (e.g., linear sweep voltammetry and stepped-current chronopotentiometry). Results show that when a carbon brush cathode was used during electrolysis with O2/O3 sparging, H2O and H2O2 reductions were usually negligible cathodic reactions. However, O3 can be preferentially reduced at much more positive potentials (ca. 0.9 V vs. SCE) than O2 (ca. -0.1 V vs. SCE) at the carbon cathode. Therefore, cathodic O2 reduction was inhibited when the process was operated under current limited conditions for cathodic O3 reduction. The inhibition of O2 reduction prevented the desired E-peroxone process (cathodic O2 reduction to H2O2 and ensuing reaction of H2O2 with O3 to OH) from occurring. In contrast, when cathodic O3 reduction was limited by O3 mass transfer to the cathode, cathodic O2 reduction to H2O2 could occur, thus enabling the E-peroxone process to enhance pollutant degradation and mineralization. Many process and water parameters (applied current, ozone dose, and reactivity of water constituents with O3) can cause fundamental changes in the cathodic reaction mechanisms, thus profoundly influencing water treatment performance during the E-peroxone process. To exploit the benefits of H2O2 in water treatment, reaction conditions should be carefully controlled to promote cathodic O

  19. Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation.

    Science.gov (United States)

    Zhou, Nana; Yang, Chen; Tucker, David

    2015-02-01

    Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system can be improved by effective management and control of the cathode airflow. The disturbances of the cathode airflow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments, using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The dynamic responses of the fuel cell component and hardware component of the hybrid system were studied in this paper.

  20. Effects of heated humidification and topical steroids on compliance, nasal symptoms, and quality of life in patients with obstructive sleep apnea syndrome using nasal continuous positive airway pressure.

    LENUS (Irish Health Repository)

    Ryan, Silke

    2012-02-01

    BACKGROUND: Nasal side effects are common in patients with obstructive sleep apnea syndrome (OSAS) starting on nasal continuous positive airway pressure (CPAP) therapy. We tested the hypothesis that heated humidification or nasal topical steroids improve compliance, nasal side effects and quality of life in this patient group. METHODS: 125 patients with the established diagnosis of OSAS (apnea\\/hypopnea index > or = 10\\/h), who tolerated CPAP via a nasal mask, and who had a successful CPAP titration were randomized to 4 weeks of dry CPAP, humidified CPAP or CPAP with additional topical nasal steroid application (fluticasone, GlaxoWellcome). Groups were similar in all demographic variables and in frequency of nasal symptoms at baseline. Outcome measures were objective compliance, quality of life (short form 36), subjective sleepiness (Epworth Sleepiness Scale score) and nasal symptoms such as runny, dry or blocked nose, sneezing and headaches; all variables assessed using a validated questionnaire and by direct interview. RESULTS: There was no difference in compliance between groups after 4 weeks (dry: 5.21 +\\/- 1.66 h\\/night, fluticasone: 5.66 +\\/- 1.68, humidifier: 5.21 +\\/- 1.84; p = 0.444). Quality of life and subjective sleepiness improved in all groups, but there were no differences in the extent of improvement. Nasal Symptoms were less frequently reported in the humidifier group (28%) than in the remaining groups (dry: 70%, fluticasone: 53%, p = 0.002). However, the addition of fluticasone resulted in increased frequency of sneezing. CONCLUSION: The addition of a humidifier, but not nasal steroids decreases the frequency of nasal symptoms in unselected OSAS patients initiating CPAP therapy; however compliance and quality of life remain unaltered.

  1. Progress of air-breathing cathode in microbial fuel cells

    Science.gov (United States)

    Wang, Zejie; Mahadevan, Gurumurthy Dummi; Wu, Yicheng; Zhao, Feng

    2017-07-01

    Microbial fuel cell (MFC) is an emerging technology to produce green energy and vanquish the effects of environmental contaminants. Cathodic reactions are vital for high electrical power density generated from MFCs. Recently tremendous attentions were paid towards developing high performance air-breathing cathodes. A typical air-breathing cathode comprises of electrode substrate, catalyst layer, and air-diffusion layer. Prior researches demonstrated that each component influenced the performance of air-breathing cathode MFCs. This review summarized the progress in development of the individual component and elaborated main factors to the performance of air-breathing cathode.

  2. Polymer coatings as separator layers for microbial fuel cell cathodes

    KAUST Repository

    Watson, Valerie J.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production. © 2010 Elsevier B.V. All rights reserved.

  3. Design of an Advanced Membrane Electrode Assembly Employing a Double-Layered Cathode for a PEM Fuel Cell.

    Science.gov (United States)

    Kim, GyeongHee; Eom, KwangSup; Kim, MinJoong; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Cho, EunAe

    2015-12-23

    The membrane electrolyte assembly (MEA) designed in this study utilizes a double-layered cathode: an inner catalyst layer prepared by a conventional decal transfer method and an outer catalyst layer directly coated on a gas diffusion layer. The double-layered structure was used to improve the interfacial contact between the catalyst layer and membrane, to increase catalyst utilization and to modify the removal of product water from the cathode. Based on a series of MEAs with double-layered cathodes with an overall Pt loading fixed at 0.4 mg cm(-2) and different ratios of inner-to-outer Pt loading, the MEA with an inner layer of 0.3 mg Pt cm(-2) and an outer layer of 0.1 mg Pt cm(-2) exhibited the best performance. This performance was better than that of the conventional single-layered electrode by 13.5% at a current density of 1.4 A cm(-2).

  4. Textile Inspired Lithium-Oxygen Battery Cathode with Decoupled Oxygen and Electrolyte Pathways.

    Science.gov (United States)

    Xu, Shaomao; Yao, Yonggang; Guo, Yuanyuan; Zeng, Xiaoqiao; Lacey, Steven D; Song, Huiyu; Chen, Chaoji; Li, Yiju; Dai, Jiaqi; Wang, Yanbin; Chen, Yanan; Liu, Boyang; Fu, Kun; Amine, Khalil; Lu, Jun; Hu, Liangbing

    2018-01-01

    The lithium-air (Li-O 2 ) battery has been deemed one of the most promising next-generation energy-storage devices due to its ultrahigh energy density. However, in conventional porous carbon-air cathodes, the oxygen gas and electrolyte often compete for transport pathways, which limit battery performance. Here, a novel textile-based air cathode is developed with a triple-phase structure to improve overall battery performance. The hierarchical structure of the conductive textile network leads to decoupled pathways for oxygen gas and electrolyte: oxygen flows through the woven mesh while the electrolyte diffuses along the textile fibers. Due to noncompetitive transport, the textile-based Li-O 2 cathode exhibits a high discharge capacity of 8.6 mAh cm -2 , a low overpotential of 1.15 V, and stable operation exceeding 50 cycles. The textile-based structure can be applied to a range of applications (fuel cells, water splitting, and redox flow batteries) that involve multiple phase reactions. The reported decoupled transport pathway design also spurs potential toward flexible/wearable Li-O 2 batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Cathodes Delivered for Space Station Plasma Contactor System

    Science.gov (United States)

    Patterson, Michael J.

    1999-01-01

    The International Space Station's (ISS) power system is designed with high-voltage solar arrays that typically operate at output voltages of 140 to 160 volts (V). The ISS grounding scheme electrically ties the habitat modules, structure, and radiators to the negative tap of the solar arrays. Without some active charge control method, this electrical configuration and the plasma current balance would cause the habitat modules, structure, and radiators to float to voltages as large as -120 V with respect to the ambient space plasma. With such large negative floating potentials, the ISS could have deleterious interactions with the space plasma. These interactions could include arcing through insulating surfaces and sputtering of conductive surfaces as ions are accelerated by the spacecraft plasma sheath. A plasma contactor system was baselined on the ISS to prevent arcing and sputtering. The sole requirement for the system is contained within a single directive (SSP 30000, paragraph 3.1.3.2.1.8): "The Space Station structure floating potential at all points on the Space Station shall be controlled to within 40 V of the ionospheric plasma potential using a plasma contactor." NASA is developing this plasma contactor as part of the ISS electrical power system. For ISS, efficient and rapid emission of high electron currents is required from the plasma contactor system under conditions of variable and uncertain current demand. A hollow cathode plasma source is well suited for this application and was, therefore, selected as the design approach for the station plasma contactor system. In addition to the plasma source, which is referred to as a hollow cathode assembly, or HCA, the plasma contactor system includes two other subsystems. These are the power electronics unit and the xenon gas feed system. The Rocketdyne Division of Boeing North American is responsible for the design, fabrication, assembly, test, and integration of the plasma contactor system. Because of

  6. Measurement of radiation and temperature of cathod spots in excimer laser discharge; Ekishima reza reiki hodennai ni fukumareru inkyoku kiten no kogakuteki kansoku to ondo no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Minamitani, Y.; Nakatani, H. [Mitsubishi Electric Corp., Tokyo (Japan)

    1996-08-20

    Excimer laser is used in various fields such as luminous source for steppers, annealing treatment, ablation process, nuclear fusion and so on. In this paper, the radiation timing and gas temperature of cathode spots, streamer discharges and glow discharges in KrF excimer are measured by observing the radiating spectra thereof. The following conclusions are obtained from the results of the present study. Cathode spots begin to radiate at about 20ns after the discharge initiation, then the first and second radiation peaks are observed respectively when the discharge current reversing after passing zero point and the reserved discharged current approaching zero point. Streamer discharge makes flashover between electrodes at the second radiation peak of cathode spots, while the glow discharges almost disappear when streamer discharges occurring. The temperatures of cathode spots and glow discharge as 5500K and 2600K respectively are almost constant and independent upon the discharging voltage of laser. 14 refs., 12 figs.

  7. Ferroelectric Cathodes in Transverse Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-07-29

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode.

  8. Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems

    NARCIS (Netherlands)

    Kuntke, P.; Zamora, P.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.

    2016-01-01

    The application of a gas-permeable hydrophobic tubular membrane in bio-electrochemical systems enables efficient recovery of ammonia (NH3) from their cathode compartments. Due to a hydrogen evolution reaction at the cathode, no chemical addition was required to increase the pH for

  9. The stationary vacuum arc on non-thermionic hot cathode

    Science.gov (United States)

    Amirov, R. Kh; Antonov, N. N.; Vorona, N. A.; Gavrikov, A. V.; Liziakin, G. D.; Polistchook, V. P.; Samoylov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M.

    2015-11-01

    Experimental study of vacuum arc with distributed spot on plumbum cathode at temperatures 1.25-1.45 kK has been presented. At these conditions current density of thermionic emission from cathode was less than 1 μA/cm2, while the mean current density on the cathode was about 10 A/cm2. Plumbum was placed in heat-insulated crucible (cathode) with external diameter 25 mm. Electron-beam heater was situated under the crucible. Arc current was changed in the range 20-70 A, arc voltage was about 15 V. The studied arc is characterized by the absence of the random voltage fluctuations; the micro particles of cathode erosion products were observed only in transition regimes. Spectral data of plasma radiation and values of the heat flow from plasma to cathode were obtained. It has been experimentally established that the evaporation rate in arc approximately two times less than without discharge. The average charge of plumbum particles in the cathode jet was in range 0.2-0.3e. Comparison of the characteristics of studied discharge on thermionic gadolinium cathode and non-thermionic cathodes was fulfilled. One can assume that ions provide the charge transfer on the cathode in the studied discharge.

  10. A definitive criterion for cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Roger [Cathodic Protection Network International Ltd., Reading (United Kingdom)

    2009-07-01

    The corrosion reaction is defined using the Pourbaix Diagram and includes consideration of the pH, temperature, pressure, nobility of the metal and conductivity of the electrolyte. The passive zone can be established in a laboratory by creating a closed circuit condition in which the voltages can be measured. Natural corrosion cells occurring in simple conditions can be evaluated for the purpose of monitoring the performance of cathodic protection. Metal pipelines are complex networks of conductors submerged in electrolyte of infinitely variable qualities. The present method used to ascertain the effectiveness of cathodic protection has many inherent errors and results in costly and unpredictable corrosion failures. An electrode has been devised to define the exact electrical status of the corrosion reaction at its location. The design allows a closed circuit measurement of the corrosion current that can determine whether or not corrosion has been stopped by cathodic protection. This has allowed the development of software that can calculate the condition and corrosion status throughout a network of pipelines, using electrical circuit analysis common in the electronics industry. (author)

  11. EXPERIMENTAL AND THEORETICAL STUDY OF ADIABATIC HUMIDIFICATION IN HVAC&R APPLICATIONS ESTUDIO TEÓRICO EXPERIMENTAL DE LA HUMIDIFICACION ADIABÁTICA EN APLICACIONES HVAC&R

    Directory of Open Access Journals (Sweden)

    Néstor Fonseca

    2010-08-01

    Full Text Available This article presents the results of the study performed to obtain a theoretical unified treatment of adiabatic humidification to be applied in refrigeration and air conditioning systems that can be used as a calculate tool in field as a part of diagnosis in audit processes of this kind of systems. To achieve this, a series of tests and experimental analysis are performed on two types of systems. The computational model is able to predict the effectiveness of the system and the main variables at the system exhaust as temperature and humidity by using the measurement of temperature and mass flow rates that participle in the energy and mass and transfer. The key in the analysis is the global heat transfer coefficient AU, considering the influence of the water an air mass flow rates in the system. An example of each system considered in this study is shown, illustrating the validation of the model.Este artículo presenta los resultados del estudio realizado para obtener un tratamiento teórico unificado de la humidificación adiabática, aplicable a sistemas de refrigeración y acondicionamiento de aire con la cual generar una herramienta de cálculo que pueda ser utilizada en terreno como parte de su diagnóstico en auditorías energéticas de este tipo de sistemas. Para lograr esto se realizan una serie de ensayos y análisis de tipo experimental en dos diferentes clases de equipo. El modelo computacional permite predecir la efectividad del sistema y principales variables de salida como la temperatura y contenido de humedad mediante la medición de las condiciones de entrada de temperatura y flujos másicos de los fluidos que intervienen en la transferencia de masa y energía. La clave en el análisis es la definición del coeficiente global de transferencia de calor AU, considerando la influencia de los flujos de agua y aire en el sistema. Se describe un ejemplo de validación del modelo por cada tipo de sistema seleccionado en este estudio.

  12. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    Science.gov (United States)

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  13. Cathode power distribution system and method of using the same for power distribution

    Science.gov (United States)

    Williamson, Mark A; Wiedmeyer, Stanley G; Koehl, Eugene R; Bailey, James L; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J

    2014-11-11

    Embodiments include a cathode power distribution system and/or method of using the same for power distribution. The cathode power distribution system includes a plurality of cathode assemblies. Each cathode assembly of the plurality of cathode assemblies includes a plurality of cathode rods. The system also includes a plurality of bus bars configured to distribute current to each of the plurality of cathode assemblies. The plurality of bus bars include a first bus bar configured to distribute the current to first ends of the plurality of cathode assemblies and a second bus bar configured to distribute the current to second ends of the plurality of cathode assemblies.

  14. Rf Gun with High-Current Density Field Emission Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  15. Preliminary experimental study of a carbon fiber array cathode

    Science.gov (United States)

    Li, An-kun; Fan, Yu-wei

    2016-08-01

    The preliminary experimental results of a carbon fiber array cathode for the magnetically insulated transmission line oscillator (MILO) operations are reported. When the diode voltage and diode current were 480 kV and 44 kA, respectively, high-power microwaves with a peak power of about 3 GW and a pulse duration of about 60 ns were obtained in a MILO device with the carbon fiber array cathode. The preliminary experimental results show that the shot-to-shot reproducibility of the diode current and the microwave power is stable until 700 shots. No obvious damage or deterioration can be observed in the carbon fiber surface morphology after 700 shots. Moreover, the cathode performance has no observable deterioration after 700 shots. In conclusion, the maintain-free lifetime of the carbon fiber array cathode is more than 700 shots. In this way, this carbon fiber array cathode offers a potential replacement for the existing velvet cathode.

  16. The glass-like glazed coating made of cathode-ray tube faceplates cullet

    Directory of Open Access Journals (Sweden)

    N.І. Zavgorodnya

    2016-05-01

    Full Text Available The tendency of the current time is to find ways of expedient municipal solid waste recycling as a secondary raw material with similar physicochemical and mechanical characteristics for the purpose of efficient use of resources and reduction of harmful impact on the environment. Due to the termination the production of monitors and television sets with cathode-ray tubes, a significant part of them is grow out of use in the form of dimensional waste. Kinescopes of these electric devices contain valuable components including the screen and conical glass and cathode-luminophors. Existing trends in the world of CRT faceplates cullet recycling argue for reasonability of recycling ways of this valuable secondary raw materials. Aim: The aim of researches is to determine the impact of the full replacement of quartz sand by faceplates cullet and using the zinc sulfide, reconstituted of used cathode-luminophors, as a secondary raw material in the production of glass-like glaze on the basic properties of color glaze. Materials and Methods: Cathode-ray tube faceplates are cut off during removal process, washed from dirt, dried, crushed by press, milled in a cheek grinder and finally crushed in a barrel mill. The slurried impurity (clay, dyes of desired color, including ZnS, water are added to this powder. The received mix is processed of wet grinding for slip production. Slip is surfaced on glass-ceramic tile, dried up, burned at maximum temperature of 900ºС. Results: Experimental research has shown that glass-forming, modifying and intermediate oxides of inorganic substances are added to the glaze with the CRT faceplates cullet. The Chasiv Yar clay belongs to the group with significant gas emission. The water vapor arising during the clay dehydration plays role of the "carrier" of heavy non-volatile components, considerably accelerates gas processes and increases activity of gas components. Zinc sulphide, dissolved in the silicate glaze melts when heated

  17. Study of the discharge gas trapping during thin film growth

    CERN Document Server

    Calatroni, Sergio; Anderle, M; Benvenuti, Cristoforo; Carver, J; Chiggiato, P; Neupert, H; Vollenberg, W

    2001-01-01

    Discharge gas trapping in thin films produced by sputtering is known to be due to high energy neutrals bouncing back from the cathode. Qualitatively, the phenomenon is enhanced by raising the discharge voltage and is strongly dependent on the atomic masses of the discharge gas and of the cathode material. In addition to these known effects it is shown that, for a given gas, the trapped amount decreases with increasing the melting temperature of the deposited material. The results obtained both by sample melting and laser ablation are presented and discussed.

  18. Structured electron beams from nano-engineered cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Lueangaramwong, A. [NICADD, DeKalb; Mihalcea, D. [NICADD, DeKalb; Andonian, G. [RadiaBeam Tech.; Piot, P. [Fermilab

    2017-03-07

    The ability to engineer cathodes at the nano-scale have open new possibilities such as enhancing quantum eciency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper we present numerical investigations of the beam dynamics associated to this class of cathode in the weak- and strong-field regimes.We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

  19. High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries

    Science.gov (United States)

    2015-04-24

    Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries Siu on Tung, Krista L. Hawthorne, Yi Ding, James Mainero, and Levi T. Thompson...Automotive Research Development and Engineering Center, Warren, MI 48387, USA Keywords: nanostructured materials, lithium ion batteries , cathode...2014 to 00-00-2015 4. TITLE AND SUBTITLE High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries 5a. CONTRACT NUMBER 5b. GRANT

  20. Reducing DRIFT Backgrounds with a Submicron Aluminized-Mylar Cathode

    OpenAIRE

    Battat, J. S. R.; Daw, E.; Dorofeev, A.; Ezeribe, A. C.; Fox, J. R.; Gauvreau, J-L.; Gold, M; Harmon, L.; Harton, J.; Lafler, R.; Landers, J.; Lauer, R. J.; Lee, E.R.; Loomba, D.; Lumnah, A.

    2015-01-01

    Background events in the DRIFT-IId dark matter detector, mimicking potential WIMP signals, are predominantly caused by alpha decays on the central cathode in which the alpha particle is completely or partially absorbed by the cathode material. We installed a 0.9 micron thick aluminized-mylar cathode as a way to reduce the probability of producing these backgrounds. We study three generations of cathode (wire, thin-film, and radiologically clean thin-film) with a focus on the ratio of backgrou...

  1. Intermetallics as advanced cathode materials in hydrogen production via electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Stojic, Dragica Lj.; Marceta Kaninski, Milica P.; Maksic, Aleksandar D.; Simic, Natasa D. [Laboratory of Physical Chemistry, Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001-Belgrade (Serbia and Montenegro); Grozdic, Tomislav D. [Centre for Multidisciplinary Studies, University of Belgrade, 11030-Belgrade (Serbia and Montenegro)

    2006-06-15

    Intermetallics phases along Mo-Pt phase diagram have been investigated as cathode materials for the production of hydrogen by electrolysis from water KOH solutions, in an attempt to increase the electrolytic process efficiency. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis, and also with the intermetallic Ti-Pt. An significant upgrade of the electrolytic efficiency using intermetallics in pure KOH electrolyte was achieved in comparison with conventional cathode materials. The effects of those cathode materials on the process efficiency were discussed in the context of transition metal features that issue from their electronic configuration. (author)

  2. Spacecraft mass spectrometer ion source employing field emission cathodes

    Science.gov (United States)

    Curtis, C. C.; Hsieh, K. C.

    1986-01-01

    An ion source that utilizes a pair of thin-film field emission cathodes to provide current for electric impact ionization is studied. The field emission cathodes are composed of microscopically small needle tips and an extraction electrode; the cathodes generate a 200-eV, 0.1-mA electron beam. The multistep process for the manufacturing of the field emission cathodes is examined. The operation of the ion source, which ionizes atoms and molecules that enter the mass spectrometer with a ram velocity of about 80 km/sec, is described.

  3. Coated particles for lithium battery cathodes

    Science.gov (United States)

    Singh, Mohit; Eitouni, Hany Basam; Pratt, Russell Clayton; Mullin, Scott Allen; Wang, Xiao-Liang

    2017-07-18

    Particles of cathodic materials are coated with polymer to prevent direct contact between the particles and the surrounding electrolyte. The polymers are held in place either by a) growing the polymers from initiators covalently bound to the particle, b) attachment of the already-formed polymers by covalently linking to functional groups attached to the particle, or c) electrostatic interactions resulting from incorporation of cationic or anionic groups in the polymer chain. Carbon or ceramic coatings may first be formed on the surfaces of the particles before the particles are coated with polymer. The polymer coating is both electronically and ionically conductive.

  4. Tailored Core Shell Cathode Powders for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, Scott [NexTech Materials, Ltd.,Lewis Center, OH (United States)

    2015-03-23

    In this Phase I SBIR project, a “core-shell” composite cathode approach was evaluated for improving SOFC performance and reducing degradation of lanthanum strontium cobalt ferrite (LSCF) cathode materials, following previous successful demonstrations of infiltration approaches for achieving the same goals. The intent was to establish core-shell cathode powders that enabled high performance to be obtained with “drop-in” process capability for SOFC manufacturing (i.e., rather than adding an infiltration step to the SOFC manufacturing process). Milling, precipitation and hetero-coagulation methods were evaluated for making core-shell composite cathode powders comprised of coarse LSCF “core” particles and nanoscale “shell” particles of lanthanum strontium manganite (LSM) or praseodymium strontium manganite (PSM). Precipitation and hetero-coagulation methods were successful for obtaining the targeted core-shell morphology, although perfect coverage of the LSCF core particles by the LSM and PSM particles was not obtained. Electrochemical characterization of core-shell cathode powders and conventional (baseline) cathode powders was performed via electrochemical impedance spectroscopy (EIS) half-cell measurements and single-cell SOFC testing. Reliable EIS testing methods were established, which enabled comparative area-specific resistance measurements to be obtained. A single-cell SOFC testing approach also was established that enabled cathode resistance to be separated from overall cell resistance, and for cathode degradation to be separated from overall cell degradation. The results of these EIS and SOFC tests conclusively determined that the core-shell cathode powders resulted in significant lowering of performance, compared to the baseline cathodes. Based on the results of this project, it was concluded that the core-shell cathode approach did not warrant further investigation.

  5. Quantifying the environmental impact of a Li-rich high-capacity cathode material in electric vehicles via life cycle assessment.

    Science.gov (United States)

    Wang, Yuqi; Yu, Yajuan; Huang, Kai; Chen, Bo; Deng, Wensheng; Yao, Ying

    2017-01-01

    A promising Li-rich high-capacity cathode material (xLi2MnO3·(1-x)LiMn0.5Ni0.5O2) has received much attention with regard to improving the performance of lithium-ion batteries in electric vehicles. This study presents an environmental impact evaluation of a lithium-ion battery with Li-rich materials used in an electric vehicle throughout the life cycle of the battery. A comparison between this cathode material and a Li-ion cathode material containing cobalt was compiled in this study. The battery use stage was found to play a large role in the total environmental impact and high greenhouse gas emissions. During battery production, cathode material manufacturing has the highest environmental impact due to its complex processing and variety of raw materials. Compared to the cathode with cobalt, the Li-rich material generates fewer impacts in terms of human health and ecosystem quality. Through the life cycle assessment (LCA) results and sensitivity analysis, we found that the electricity mix and energy efficiency significantly influence the environmental impacts of both battery production and battery use. This paper also provides a detailed life cycle inventory, including firsthand data on lithium-ion batteries with Li-rich cathode materials.

  6. Synthesis of thick diamond films by direct current hot-cathode plasma chemical vapour deposition

    CERN Document Server

    Jin Zeng Sun; Bai Yi Zhen; Lu Xian Yi

    2002-01-01

    The method of direct current hot-cathode plasma chemical vapour deposition has been established. A long-time stable glow discharge at large discharge current and high gas pressure has been achieved by using a hot cathode in the temperature range from 1100 degree C to 1500 degree C and non-symmetrical configuration of the poles, in which the diameter of the cathode is larger than that of anode. High-quality thick diamond films, with a diameter of 40-50 mm and thickness of 0.5-4.2 mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates between 5-10 mu m/h. Most of the thick diamond films have thermal conductivities of 10-12 W/K centre dot cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved

  7. A high performance cathode for proton conducting solid oxide fuel cells

    KAUST Repository

    Wang, Zhiquan

    2015-01-01

    Intermediate temperature solid-oxide fuel cells (IT-SOFCs)), as one of the energy conversion devices, have attracted worldwide interest for their great fuel efficiency, low air pollution, much reduced cost and excellent longtime stability. In the intermediate temperature range (500-700°C), SOFCs based on proton conducting electrolytes (PSOFCs) display unique advantages over those based on oxygen ion conducting electrolytes. A key obstacle to the practical operation of past P-SOFCs is the poor stability of the traditionally used composite cathode materials in the steam-containing atmosphere and their low contribution to proton conduction. Here we report the identification of a new Ruddlesden-Popper-type oxide Sr3Fe2O7-δ that meets the requirements for much improved long-term stability and shows a superior single-cell performance. With a Sr3Fe2O7-δ-5 wt% BaZr0.3Ce0.5Y0.2O3-δ cathode, the P-SOFC exhibits high power densities (683 and 583 mW cm-2 at 700°C and 650°C, respectively) when operated with humidified hydrogen as the fuel and air as the cathode gas. More importantly, no decay in discharging was observed within a 100 hour test. © The Royal Society of Chemistry 2015.

  8. Beam Current Increase and Cathode Lifetime Improvement of KOTRON-13 Ion Source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W. K.; Chae, S. K.; Song, J. Y.; Im, G. S.; Cho, B. O. [Samyoung Unitech Co., Seoul (Korea, Republic of)

    2010-05-15

    Technology of cyclotron has been actively developed to meet the increasing requirement output of medical radioactive isotopes for PET. KOTRON-13 is produced with low negative hydrogen ion beam current owing to the low efficiency of proton beam current compared with foreign cyclotron. In the defect there from, the lifetime of cathode is around 5,000min, which requires frequent maintenance period, and the target beam current is maximum 50uA at a poor efficiency compared with the inflow quantity of hydrogen gas and that of inflicting arc current. Considering above affairs, we have to improve the PIG ion source extraction efficiency of KOTRON-13 in order to lift beam current. Mostly the ion source of cyclotron less than 30Mev comes from the use of PIG ion source mainly with the method of cold cathode or hot cathode. However, the cyclotron of 30Mev grade of EBCO or IBA uses the external ion source and uses ion source with cusp type of good withdrawal efficiency. This type requires high voltage, and transports ion from ion source to cyclotron, which requires precise transportation equipment. And entering cyclotron requires a high quality of inflictor with a high defect rate, but high current cyclotron has no choice but to use ion source of such a method. But the cyclotron using PET with the beam current less than 100uA uses PIG ion source of KOTRON-13 with a reasonable maintenance cost

  9. Reactant gas composition for fuel cell potential control

    Science.gov (United States)

    Bushnell, Calvin L.; Davis, Christopher L.

    1991-01-01

    A fuel cell (10) system in which a nitrogen (N.sub.2) gas is used on the anode section (11) and a nitrogen/oxygen (N.sub.2 /O.sub.2) gaseous mix is used on the cathode section (12) to maintain the cathode at an acceptable voltage potential during adverse conditions occurring particularly during off-power conditions, for example, during power plant shutdown, start-up and hot holds. During power plant shutdown, the cathode section is purged with a gaseous mixture of, for example, one-half percent (0.5%) oxygen (O.sub.2) and ninety-nine and a half percent (99.5%) nitrogen (N.sub.2) supplied from an ejector (21) bleeding in air (24/28) into a high pressure stream (27) of nitrogen (N.sub.2) as the primary or majority gas. Thereafter the fuel gas in the fuel processor (31) and the anode section (11) is purged with nitrogen gas to prevent nickel (Ni) carbonyl from forming from the shift catalyst. A switched dummy electrical load (30) is used to bring the cathode potential down rapidly during the start of the purges. The 0.5%/99.5% O.sub.2 /N.sub.2 mixture maintains the cathode potential between 0.3 and 0.7 volts, and this is sufficient to maintain the cathode potential at 0.3 volts for the case of H.sub.2 diffusing to the cathode through a 2 mil thick electrolyte filled matrix and below 0.8 volts for no diffusion at open circuit conditions. The same high pressure gas source (20) is used via a "T" juncture ("T") to purge the anode section and its associated fuel processor (31).

  10. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source.

    Science.gov (United States)

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry.

  11. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    Energy Technology Data Exchange (ETDEWEB)

    Sloan Roberts, F.; Anderson, Scott L. [Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112 (United States)

    2013-12-15

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry.

  12. The study of neutron burst shape of a neutron tube driven by dispenser cathode

    Science.gov (United States)

    Grishnyaev, Evgeny; Polosatkin, Sergey

    2016-08-01

    A slim-shaped portable DD-neutron generator is developed at Budker institute of Nuclear Physics. The generator is a combination of Cockcroft-Walton voltage multiplier and a sealed gas-filled neutron tube driven by dispenser cathode. Neutron burst shape in pulsed mode of neutron tube operation is measured with stroboscopic time spectrometry, implemented on scintillation detector, and modeled with Comsol Script 1.3 and Comsol Multiphysics 3.5. Modeling appears to be in good agreement with experimental results. Measured pulse rise and fall times are 110 ns and 100 ns respectively.

  13. The study of neutron burst shape of a neutron tube driven by dispenser cathode

    Energy Technology Data Exchange (ETDEWEB)

    Grishnyaev, Evgeny, E-mail: grishnjaev@mail.ru; Polosatkin, Sergey

    2016-08-21

    A slim-shaped portable DD-neutron generator is developed at Budker institute of Nuclear Physics. The generator is a combination of Cockcroft–Walton voltage multiplier and a sealed gas-filled neutron tube driven by dispenser cathode. Neutron burst shape in pulsed mode of neutron tube operation is measured with stroboscopic time spectrometry, implemented on scintillation detector, and modeled with Comsol Script 1.3 and Comsol Multiphysics 3.5. Modeling appears to be in good agreement with experimental results. Measured pulse rise and fall times are 110 ns and 100 ns respectively.

  14. High catalytic activity and pollutants resistivity using Fe-AAPyr cathode catalyst for microbial fuel cell application

    OpenAIRE

    Carlo Santoro; Alexey Serov; Claudia W. Narvaez Villarrubia; Sarah Stariha; Sofia Babanova; Kateryna Artyushkova; Andrew J. Schuler; Plamen Atanassov

    2015-01-01

    For the first time, a new generation of innovative non-platinum group metal catalysts based on iron and aminoantipyrine as precursor (Fe-AAPyr) has been utilized in a membraneless single-chamber microbial fuel cell (SCMFC) running on wastewater. Fe-AAPyr was used as an oxygen reduction catalyst in a passive gas-diffusion cathode and implemented in SCMFC design. This catalyst demonstrated better performance than platinum (Pt) during screening in ?clean? conditions (PBS), and no degradation in ...

  15. Cathodic disbonding of organic coatings on submerged steel

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, Ole oeystein

    1998-12-31

    In offshore oil production, submerged steel structures are commonly protected by an organic coating in combination with cathodic protection. The main advantage is that the coating decreases the current demand for cathodic protection. But the coating degrades with time. This thesis studies one of the most important mechanisms for coating degradation in seawater, cathodic disbonding. Seven commercial coatings and two model coatings with various pigmentations have been studied. Parameter studies, microscopy and studies of free films were used in the mechanism investigations. Exposure to simulated North Sea conditions was used in the performance studies. The effect of aluminium and glass barrier pigments on cathodic disbonding was investigated. The mechanism for the effect of the aluminium pigments on cathodic disbonding was also investigated. The transport of charge and oxygen to the steel/coating interface during cathodic disbonding was studied for two epoxy coatings. Cathodic disbonding, blistering and current demand for cathodic protection was measured for nine commercial coatings for submerged steel structures, using the ASTM-G8 standard test and a long term test under simulated North Sea conditions. The relevance of the ASTM-G8 test as a prequalification test was evaluated. 171 refs., 40 figs., 6 tabs.

  16. Development of cathode material for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Rustam Mukhtaruly Turganaly

    2014-08-01

    Full Text Available The electrochemical characteristics of the cathode material coated with carbon layer has been developed. Various carbon coating methods. There  has been carried out a comparative electrochemical analysis of the coated and uncoated with carbon cathode material. 

  17. Impressed current cathodic protection of deep water structures

    Digital Repository Service at National Institute of Oceanography (India)

    Venkatesan, R.

    Of all the various anti-corrosion systems usEd. by offshore structures and ship-building industry to reduce the ravages of sea-water corrosion, cathodic protection is one of the most important. Impressed current cathodic protection (ICCP...

  18. Cathode potential drop in the channel of a magnetoplasma compressor

    Energy Technology Data Exchange (ETDEWEB)

    Shubin, A.P.

    1977-09-01

    Calculations are carried out for the dissipationless plasma flow in the channel of a magnetoplasma compressor when there is a potential drop near the cathode. This drop appears when the current is carried by ions as the result of the disappearance of ions at the cathode.

  19. A Statistical Approach to the Modified Impress Current Cathodic ...

    African Journals Online (AJOL)

    An attempt to predict theoretically, the corrosion protection of oil pipelines by Impressed Current Cathodic Protection (ICCP) was embarked upon using data from an ICCP system in practice for three years (2004 through 2006). The concepts and principles used in Cathodic protection is briefly explained with a discussion of ...

  20. Cathodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    that these nanoparticulate infiltrates have good oxygen reduction capabilities. The significance of the choice of ionic conducting backbone was also addressed by replacing the CGO with Bi2V0.9Cu0.1O5.35 (BICUVOX). Cathodes with a BICUVOX backbone exhibit performance degradation not observed in LSC infiltrated - CGO cathodes...

  1. Single-layer graphene cathodes for organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Marshall P.; Gorodetsky, Alon A.; Kim, Bumjung; Kim, Keun Soo; Jia, Zhang; Kim, Philip; Nuckolls, Colin; Kymissis, Ioannis

    2011-01-01

    A laminated single-layer graphene is demonstrated as a cathode for organic photovoltaicdevices. The measured properties indicate that graphene offers two potential advantages over conventional photovoltaic electrode materials; work function matching via contact doping, and increased power conversion efficiency due to transparency. These findings indicate that flexible, light-weight all carbon solar cells can be constructed using graphene as the cathode material.

  2. Microbial Fuel Cell Performance with a Pressurized Cathode Chamber

    Science.gov (United States)

    Microbial fuel cell (MFC) power densities are often constrained by the oxygen reduction reaction rate on the cathode electrode. One important factor for this is the normally low solubility of oxygen in the aqueous cathode solution creating mass transport limitations, which hinder oxygen reduction a...

  3. Impedance Modeling of Solid Oxide Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Mortensen, Jakob Egeberg; Søgaard, Martin; Jacobsen, Torben

    2010-01-01

    A 1-dimensional impedance model for a solid oxide fuel cell cathode is formulated and applied to a cathode consisting of 50/50 wt% strontium doped lanthanum cobaltite and gadolinia doped ceria. A total of 42 impedance spectra were recorded in the temperature range: 555-852°C and in the oxygen...

  4. The Effect of Substrate Topography on Coating Cathodic Delamination

    DEFF Research Database (Denmark)

    Erik Weinell, Claus; Sørensen, Per A.; Kiil, Søren

    2011-01-01

    This article describes the effect of steel substrate topography on coating cathodic delamination. The study showed that the surface preparation can be used to control and minimize the rate of cathodic delamination. The coating should have maximum wetting properties so that substrates with high...

  5. Plasma-induced field emission study of carbon nanotube cathode

    Directory of Open Access Journals (Sweden)

    Yi Shen

    2011-10-01

    Full Text Available An investigation on the plasma-induced field emission (PFE properties of a large area carbon nanotube (CNT cathode on a 2 MeV linear induction accelerator injector is presented. Experimental results show that the cathode is able to emit intense electron beams. Intense electron beams of 14.9–127.8  A/cm^{2} are obtained from the cathode. The CNT cathode desorbs gases from the CNTs during the PFE process. The fast cathode plasma expansion affects the diode perveance. The amount of outgassing is estimated to be 0.06–0.49  Pa·L, and the ratio of outgassing and electron are roughly calculated to be within the range of 170–350 atoms per electron. The effect of the outgassing is analyzed, and the outgassing mass spectrum of the CNT cathode has been studied during the PFE. There is a significant desorption of CO_{2}, N_{2}(CO, and H_{2} gases, which plays an important role during the PFE process. All the experiments demonstrate that the outgassing plays an important role in the formation of the cathode plasma. Moreover, the characteristic turn-on time of the CNT cathode was measured to be 39 ns.

  6. Cathode Stalk Cooling System for the MK 1 Quarterwave Gun

    Science.gov (United States)

    2012-06-01

    20 Figure 9. Cross section of the cavity with the coupler and cathode stalk installed (After [11...focusing magnets focus the electron beam envelope transversely to the propagation axis. Bending and focusing magnets are analogous to prisms and lenses...each of these layers. Figure 9. Cross section of the cavity with the coupler and cathode stalk installed (After [11]). 25 To transform the

  7. A hollow cathode ion source for production of primary ions for the BNL electron beam ion source

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, James, E-mail: alessi@bnl.gov; Beebe, Edward; Carlson, Charles; McCafferty, Daniel; Pikin, Alexander; Ritter, John [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2014-02-15

    A hollow cathode ion source, based on one developed at Saclay, has been modified significantly and used for several years to produce all primary 1+ ions injected into the Relativistic Heavy Ion Collider Electron Beam Ion Source (EBIS) at Brookhaven. Currents of tens to hundreds of microamperes have been produced for 1+ ions of He, C, O, Ne, Si, Ar, Ti, Fe, Cu, Kr, Xe, Ta, Au, and U. The source is very simple, relying on a glow discharge using a noble gas, between anode and a solid cathode containing the desired species. Ions of both the working gas and ionized sputtered cathode material are extracted, and then the desired species is selected using an ExB filter before being transported into the EBIS trap for charge breeding. The source operates pulsed with long life and excellent stability for most species. Reliable ignition of the discharge at low gas pressure is facilitated by the use of capacitive coupling from a simple toy plasma globe. The source design, and operating experience for the various species, is presented.

  8. Diffuse vacuum arc with cerium oxide hot cathode

    Science.gov (United States)

    Amirov, R. Kh; Vorona, N. A.; Gavrikov, A. V.; Liziakin, G. D.; Polistchook, V. P.; Samoylov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M.; Ivanov, A. S.

    2016-11-01

    Diffuse vacuum arc with hot cathode is one of the perspective plasma sources for the development of spent nuclear fuel plasma reprocessing technology. Experimental data is known for such type of discharges on metal cathodes. In this work discharge with cerium dioxide hot cathode was studied. Cerium dioxide properties are similar to uranium dioxide. Its feature as dielectric is that it becomes conductive in oxygen-free atmosphere. Vacuum arc was studied at following parameters: cathode temperatures were between 2.0 and 2.2 kK, discharge currents was between 30 and 65 A and voltages was in range from 15 to 25 V. Power flows from plasma to cathode were estimated in achieved regimes. Analysis of generated plasma component composition was made by radiation spectrum diagnostics. These results were compared with calculations of equilibrium gaseous phase above solid sample of cerium dioxide in close to experimental conditions. Cerium dioxide vacuum evaporation rate and evaporation rate in arc were measured.

  9. Gas and Gas Pains

    Science.gov (United States)

    ... Gas and gas pains Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  10. A one-dimensional model illustrating virtual-cathode formation in a novel coaxial virtual-cathode oscillator.

    CSIR Research Space (South Africa)

    Turner, GR

    2014-09-01

    Full Text Available A one-dimensional electrostatic sheet model of a coaxial geometry Virtual Cathode Oscillator (VCO) is presented. The cathode is centrally located and connects to a peripherally located plate electrode to form a resonant cavity, and is thus...

  11. Electric field induced salt precipitation into activated carbon air-cathode causes power decay in microbial fuel cells.

    Science.gov (United States)

    An, Jingkun; Li, Nan; Wan, Lili; Zhou, Lean; Du, Qing; Li, Tian; Wang, Xin

    2017-10-15

    As a promising design for the real application of microbial fuel cells (MFCs) in wastewater treatment, activated carbon (AC) air-cathode is suffering from a serious power decay after long-term operation. However, the decay mechanism is still not clear because of the complex nature of contaminations. Different from previous reports, we found that local alkalinization and natural evaporation had an ignorable effect on cathode performance (∼2% decay on current densities), while electric field induced salt precipitation (∼53%) and biofouling (∼37%) were dominant according to the charge transfer resistance, which decreased power desities by 36% from 1286 ± 30 to 822 ± 23 mW m -2 in 6 months. Biofouling can be removed by scrapping, however, electric field induced salt precipitation under biofilm still clogged 37% of specific area in catalyst layer, which was even seen to penetrate through the gas diffusion layer. Our findings provided a new insight of AC air-cathode performance decay, providing important information for the improvement of cathodic longevity in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Cationic fluorinated polymer binders for microbial fuel cell cathodes

    KAUST Repository

    Chen, Guang

    2012-01-01

    Fluorinated quaternary ammonium-containing polymers were used as catalyst binders in microbial fuel cell (MFC) cathodes. The performance of the cathodes was examined and compared to NAFION ® and other sulfonated aromatic cathode catalyst binders using linear sweep voltammetry (LSV), impedance spectroscopy, and performance tests in single chamber air-cathode MFCs. The cathodes with quaternary ammonium functionalized fluorinated poly(arylene ether) (Q-FPAE) binders showed similar current density and charge transfer resistance (R ct) to cathodes with NAFION ® binders. Cathodes containing either of these fluorinated binders exhibited better electrochemical responses than cathodes with sulfonated or quaternary ammonium-functionalized RADEL ® poly(sulfone) (S-Radel or Q-Radel) binders. After 19 cycles (19 d), the power densities of all the MFCs declined compared to the initial cycles due to biofouling at the cathode. MFC cathodes with fluorinated polymer binders (1445 mW m -2, Q-FPAE-1.4-H; 1397 mW m -2, Q-FPAE-1.4-Cl; 1277 mW m -2, NAFION ®; and 1256 mW m -2, Q-FPAE-1.0-Cl) had better performance than those with non-fluorinated polymer binders (880 mW m -2, S-Radel; 670 mW m -2, Q-Radel). There was a 15% increase in the power density using the Q-FPAE binder with a 40% higher ion exchange capacity (Q-FPAE-1.4-H compared to Q-FPAE-1.0-Cl) after 19 cycles of operation, but there was no effect on the power production due to counter ions in the binder (Cl -vs. HCO 3 -). The highest-performance cathodes (NAFION ® and Q-FPAE binders) had the lowest charge transfer resistances (R ct) in fresh and in fouled cathodes despite the presence of thick biofilms on the surface of the electrodes. These results show that fluorinated binders may decrease the penetration of the biofilm and associated biopolymers into the cathode structure, which helps to combat MFC performance loss over time. © 2012 The Royal Society of Chemistry.

  13. Gas laser with dual plasma mixing

    Science.gov (United States)

    Pinnaduwage, Lal A.

    1999-01-01

    A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity.

  14. Cathodic Cage Plasma Nitriding: An Innovative Technique

    Directory of Open Access Journals (Sweden)

    R. R. M. de Sousa

    2012-01-01

    Full Text Available Cylindrical samples of AISI 1020, AISI 316, and AISI 420 steels, with different heights, were simultaneously treated by a new technique of ionic nitriding, entitled cathodic cage plasma nitriding (CCPN, in order to evaluate the efficiency of this technique to produce nitrided layers with better properties compared with those obtained using conventional ionic nitriding technique. This method is able to eliminate the edge effect in the samples, promoting a better uniformity of temperature, and consequently, a smaller variation of the thickness/height relation can be obtained. The compound layers were characterized by X-ray diffraction, optical microscopy, and microhardness test profile. The results were compared with the properties of samples obtained with the conventional nitriding, for the three steel types. It was verified that samples treated by CCPN process presented, at the same temperature, a better uniformity in the thickness and absence of the edge effect.

  15. Ion cumulation by conical cathode electrolysis.

    CERN Document Server

    Grishin, V G

    2002-01-01

    Results of solid-state sodium stearate electrolysis with conical and cylindrical cathodes is presented here. Both electric measurement and conical samples destruction can be explained if a stress developing inside the conical sample is much bigger than in the cylindrical case and there is its unlimited amplification along cone slopes. OTHER KEYWORDS: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ...

  16. High performance S-type cathode

    Energy Technology Data Exchange (ETDEWEB)

    Chu, M.Y.; Visco, S.J.; De Jonghe, L.C. [PolyPlus Battery Co., Berkeley, CA (United States)

    1997-12-01

    PolyPlus Battery Company (PPBC) is developing an advanced lithium polymer rechargeable battery based on proprietary positive electrode chemistry. In one formulation, this electrode contains elemental sulfur, either free or in association with secondary materials that promote its utilization. Batteries based on this cathode chemistry offer high steady-state (>250 W/kg) and high peak power densities (3,000 W/kg), in a low cost and environmentally benign format. High energy density, in excess of 500 Wh/kg (600 Wh/l) can also be achieved. The high power and energy densities, along with the low toxicity and low cost of materials used in the PolyPlus solid-state cells make this battery exceptionally attractive for both hybrid and electric vehicles, and for consumer electronic applications.

  17. Performance of Stainless Steel Mesh Cathode and PVDF-graphite Cathode in Microbial Fuel Cells

    Science.gov (United States)

    Huang, Liping; Tian, Ying; Li, Mingliang; He, Gaohong; Li, Zhikao

    2010-11-01

    Inexpensive and conductive materials termed as stainless steel mesh and polyvinylidene fluoride (PVDF)-graphite were currently used as the air cathode electrodes in MFCs for the investigation of power production. By loading PTFE (poly(tetrafluoroethylene)) on the surface of stainless steel mesh, electricity production reached 3 times as high as that of the naked stainless steel. A much high catalytic activity for oxygen reduction was exhibited by Pt based and PTFE loading stainless steel mesh cathode, with an electricity generation of 1144±44 mW/m2 (31±1 W/m3) and a Coulombic efficiency (CE) of 77±2%. When Pt was replaced by an inexpensive transition metal based catalyst (cobalt tetramethylphenylporphyrin, CoTMPP), power production and CE were 845±21 mW/m2 (23±1 W/m3) and 68±1%, respectively. Accordingly, power production from PVDF-graphite (hydrophobic) MFC and PVDF-graphite (hydrophile) MFC were 286±20 mW/m2(8±1 W/m3) and 158±13 mW/m2(4±0.4 W/m3), respectively using CoTMPP as catalyst. These results give us new insight into materials like stainless steel mesh and PVDF-graphite as low cost cathode for reducing the costs of MFCs for wastewater treatment applications.

  18. Synchrotron X-Ray Studies of Model SOFC Cathodes, Part I: Thin Film Cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kee-Chul; Ingram, Brian; Ilavsky, Jan; Lee, Shiwoo; Fuoss, Paul; You, Hoydoo

    2017-11-15

    We present synchrotron x-ray investigations of thin film La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) model cathodes for solid oxide fuel cells, grown on electrolyte substrates by pulse laser deposition, in situ during half-cell operations. We observed dynamic segregations of cations, such as Sr and Co, on the surfaces of the film cathodes. The effects of temperature, applied potentials, and capping layers on the segregations were investigated using a surfacesensitive technique of total external reflection x-ray fluorescence. We also studied patterned thin film LSCF cathodes using high-resolution micro-beam diffraction measurements. We find chemical expansion decreases for narrow stripes. This suggests the expansion is dominated by the bulk pathway reactions. The chemical expansion vs. the distance from the electrode contact was measured at three temperatures and an oxygen vacancy activation energy was estimated to be ~1.4 eV.

  19. Using cathode spacers to minimize reactor size in air cathode microbial fuel cells

    KAUST Repository

    Yang, Qiao

    2012-04-01

    Scaling up microbial fuel cells (MFCs) will require more compact reactor designs. Spacers can be used to minimize the reactor size without adversely affecting performance. A single 1.5mm expanded plastic spacer (S1.5) produced a maximum power density (973±26mWm -2) that was similar to that of an MFC with the cathode exposed directly to air (no spacer). However, a very thin spacer (1.3mm) reduced power by 33%. Completely covering the air cathode with a solid plate did not eliminate power generation, indicating oxygen leakage into the reactor. The S1.5 spacer slightly increased columbic efficiencies (from 20% to 24%) as a result of reduced oxygen transfer into the system. Based on operating conditions (1000ς, CE=20%), it was estimated that 0.9Lh -1 of air would be needed for 1m 2 of cathode area suggesting active air flow may be needed for larger scale MFCs. © 2012 Elsevier Ltd.

  20. Mixed polyanion glass cathodes: Iron phosphate vanadate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kercher, Andrew K [ORNL; Ramey, Joanne Oxendine [ORNL; Carroll, Kyler J [Massachusetts Institute of Technology (MIT); Kiggans Jr, James O [ORNL; Veith, Gabriel M [ORNL; Meisner, Roberta [Oak Ridge National Laboratory (ORNL); Boatner, Lynn A [ORNL; Dudney, Nancy J [ORNL

    2014-01-01

    Mixed polyanion (MP) glasses have been investigated for use as cathodes in lithium ion batteries. MP glass cathodes are similar in composition to theoretically promising crystalline polyanionic (CP) cathodes (e.g., lithium cobalt phosphate, lithium manganese silicate), but with proper polyanion substitution, they can be designed to overcome the key shortcomings of CP cathodes, such as poor electrical conductivity and irreversible phase changes. Iron phosphate/vanadate glasses were chosen as a first demonstration of the MP glass concept. Polyanion substitution with vanadate was shown to improve the intercalation capacity of an iron phosphate glass from almost zero to full theoretical capacity. In addition, the MP glass cathodes also exhibited an unexpected second high-capacity electrochemical reaction. X-ray absorption near-edge structure (XANES) and x-ray diffraction (XRD) of cathodes from cells having different states of charge suggested that this second electrochemical reaction is a glass-state conversion reaction. With a first demonstration established, MP glass materials utilizing an intercalation and/or glass-state conversion reaction are promising candidates for future high-energy cathode research.

  1. High Performance Cathodes for Li-Air Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yangchuan

    2013-08-22

    The overall objective of this project was to develop and fabricate a multifunctional cathode with high activities in acidic electrolytes for the oxygen reduction and evolution reactions for Li-air batteries. It should enable the development of Li-air batteries that operate on hybrid electrolytes, with acidic catholytes in particular. The use of hybrid electrolytes eliminates the problems of lithium reaction with water and of lithium oxide deposition in the cathode with sole organic electrolytes. The use of acid electrolytes can eliminate carbonate formation inside the cathode, making air breathing Li-air batteries viable. The tasks of the project were focused on developing hierarchical cathode structures and bifunctional catalysts. Development and testing of a prototype hybrid Li-air battery were also conducted. We succeeded in developing a hierarchical cathode structure and an effective bifunctional catalyst. We accomplished integrating the cathode with existing anode technologies and made a pouch prototype Li-air battery using sulfuric acid as catholyte. The battery cathodes contain a nanoscale multilayer structure made with carbon nanotubes and nanofibers. The structure was demonstrated to improve battery performance substantially. The bifunctional catalyst developed contains a conductive oxide support with ultra-low loading of platinum and iridium oxides. The work performed in this project has been documented in seven peer reviewed journal publications, five conference presentations, and filing of two U.S. patents. Technical details have been documented in the quarterly reports to DOE during the course of the project.

  2. Neutral hydrophilic cathode catalyst binders for microbial fuel cells

    KAUST Repository

    Saito, Tomonori

    2011-01-01

    Improving oxygen reduction in microbial fuel cell (MFC) cathodes requires a better understanding of the effects of the catalyst binder chemistry and properties on performance. A series of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) polymers with systematically varying hydrophilicity were designed to determine the effect of the hydrophilic character of the binder on cathode performance. Increasing the hydrophilicity of the PS-b-PEO binders enhanced the electrochemical response of the cathode and MFC power density by ∼15%, compared to the hydrophobic PS-OH binder. Increased cathode performance was likely a result of greater water uptake by the hydrophilic binder, which would increase the accessible surface area for oxygen reduction. Based on these results and due to the high cost of PS-b-PEO, the performance of an inexpensive hydrophilic neutral polymer, poly(bisphenol A-co-epichlorohydrin) (BAEH), was examined in MFCs and compared to a hydrophilic sulfonated binder (Nafion). MFCs with BAEH-based cathodes with two different Pt loadings initially (after 2 cycles) had lower MFC performance (1360 and 630 mW m-2 for 0.5 and 0.05 mg Pt cm-2) than Nafion cathodes (1980 and 1080 mW m -2 for 0.5 and 0.05 mg Pt cm-2). However, after long-term operation (22 cycles, 40 days), power production of each cell was similar (∼1200 and 700-800 mW m-2 for 0.5 and 0.05 mg Pt cm-2) likely due to cathode biofouling that could not be completely reversed through physical cleaning. While binder chemistry could improve initial electrochemical cathode performance, binder materials had less impact on overall long-term MFC performance. This observation suggests that long-term operation of MFCs will require better methods to avoid cathode biofouling. © 2011 The Royal Society of Chemistry.

  3. Characterisation of corrosion products on pipeline steel under cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Lanarde, Lise [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France)]|[UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Campaignolle, Xavier; Karcher, Sebastien; Meyer, Michel [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France); Joiret, Suzanne [UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu 75252 Paris Cedex 05 (France)

    2004-07-01

    Onshore gas transmission lines are conjointly protected against external corrosion by cathodic protection (CP) and organic coatings. If both protection systems are simultaneously faulty, the pipe may be subjected to local loss of protection criteria. Consequently, the development of a corrosion due to the ground intrinsic corrosiveness may occur. To guarantee an optimal and safe use of its 31000 km buried gas transmission network, Gaz de France regularly inspects its pipelines. When indications of metal damage are suspected, excavations are realized to carry out a finer diagnosis and, if necessary, to repair. Whenever, corrosions are encountered, although it occurs very scarcely, it is necessary to evaluate its degree of gravity: activity, mechanism, and kinetics. Among corrosion defects, it is indeed essential to differentiate those active, from those older inactive at the time of excavation, since those last ones may possibly have been annihilated, by a PC reinforcement for instance. Eventually, the identification of the corrosion mechanism and its associated rate will provide an assessment of the risks encountered by other sections of the pipeline similar to that excavated. This study investigates to what extent the degree of gravity (activity, kinetics) of a corrosion can be determined by the characterization and identification of its associated corrosion products. Moreover, it will attempt to relate it to the close environment features as well as to the operating conditions of the pipe. The preliminary results presented in this paper consist in a laboratory study of the time evolution of corrosion products formed on the surface of ordinary low carbon steel samples. The specimens have been previously subjected to various polarization conditions in various aqueous media. The selected solutions are characteristic of ground waters. The main parameters considered for the definition of the media were its initial chemical composition, pH and dissolved gas composition

  4. Study on the water flooding in the cathode of direct methanol fuel cells.

    Science.gov (United States)

    Im, Hun Suk; Kim, Sang-Kyung; Lim, Seongyop; Peck, Dong-Hyun; Jung, Doohwan; Hong, Won Hi

    2011-07-01

    Water flooding phenomena in the cathode of direct methanol fuel cells were analyzed by using electrochemical impedance spectroscopy. Two kinds of commercial gas diffusion layers with different PTFE contents of 5 wt% (GDL A5) and 20 wt% (GDL B20) were used to investigate the water flooding under various operating conditions. Water flooding was divided into two types: catalyst flooding and backing flooding. The cathode impedance spectra of each gas diffusion layer was obtained and compared under the same conditions. The diameter of the capacitive semicircle became larger with increasing current density for both, and this increase was greater for GDL B20 than GDL A5. Catalyst flooding is dominant and backing flooding is negligible when the air flow rate is high and current density is low. An equivalent model was suggested and fitted to the experimental data. Parameters for catalyst flooding and backing flooding were individually obtained. The capacitance of the catalyst layer decreases as the air flow rate decreases when the catalyst flooding is dominant.

  5. Iron phosphate materials as cathodes for lithium batteries

    CERN Document Server

    Prosini, Pier Paolo

    2011-01-01

    ""Iron Phosphate Materials as Cathodes for Lithium Batteries"" describes the synthesis and the chemical-physical characteristics of iron phosphates, and presents methods of making LiFePO4 a suitable cathode material for lithium-ion batteries. The author studies carbon's ability to increase conductivity and to decrease material grain size, as well as investigating the electrochemical behaviour of the materials obtained. ""Iron Phosphate Materials as Cathodes for Lithium Batteries"" also proposes a model to explain lithium insertion/extraction in LiFePO4 and to predict voltage profiles at variou

  6. Final Report: Wetted Cathodes for Low-Temperature Aluminum Smelting

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Craig W

    2002-09-30

    A low-temperature aluminum smelting process being developed differs from the Hall-Heroult process in several significant ways. The low-temperature process employs a more acidic electrolyte than cryolite, an alumina slurry, oxygen-generating metal anodes, and vertically suspended electrodes. Wetted and drained vertical cathodes are crucial to the new process. Such cathodes represent a significant portion of the capital costs projected for the new technology. Although studies exist of wetted cathode technology with Hall-Heoult cells, the differences make such a study desirable with the new process.

  7. Cathode erosion tests for 30 kW arcjets

    Science.gov (United States)

    Deininger, W. D.; Chopra, A.; Goodfellow, K. D.

    1989-01-01

    Endurance tests (100 hours) were conducted to examine the effects of geometry and spacing on 30 kW arcjet cathode erosion. The effects of input power source ripple were also examined. The preliminary results from a 413 hour endurance test are also discussed. This test was terminated voluntarily. The condition of the nozzle, boron nitride propellant injector, and cathode are discussed. A modeling effort is described which is aimed at quantifying the cathode tip heating phenomena. The results of the experiments and the model are compared.

  8. Development of Electron Gun of Carbon Nanotube Cathode

    CERN Document Server

    Hozumi, Yasufumi; Ohsawa, Satoshi; Sugimura, Takashi

    2005-01-01

    We are developing high brightness electron guns utilizing carbon nanotube (CNT) cathodes. Recently, we succeeded to achieved field emission currents to 0.2 A (3 A/cm2) from a triode type CNT cathode of 3 mm diameter. The emission tests were performed at DC100kV acceleration voltage in pulse operations of 50 Hz using 6 nsec pulses. The emission currents were very stable for long term periods of 3 weeks. Photo emission tests from CNT cathode by 266nm laser pulses is also due to be reported simultaneously.

  9. Effects of strong cathodic polarization of the Ni-YSZ interface

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Chen, Ming; Jacobsen, Torben

    2016-01-01

    resulted. Impedance spectroscopy shows initial decrease but later increase in the series resistance and polarization resistance during the 140-160 h of polarization, and significant inductive behavior. An intermetallic Ni-Zr phase that formed during polarization was preserved when the polarization was kept......Long-term strong cathodic polarization experiments of down to -2.4 V vs. E°(O2) of the Ni-YSZ interface were performed at 900°C in 97% H2/3% H2O on model electrodes. The Ni-YSZ interface underwent extensive changes and a large affected volume with a complex microstructure and phase distribution...... during cooling, and was identified post-mortem by transmission electron microscopy as Ni7Zr2. ZrO2 nanoparticles were formed on the Ni-gas surface next to the Ni-YSZ-gas triple phase boundary. Explanations of the observed features are offered based on electron microscopy and impedance spectroscopy....

  10. In-FEEP ion beam neutralization with thermionic and field emission cathodes

    Science.gov (United States)

    Marrese, C.; Polk, J.; Mueller, J.; Owens, A.; Tajmar, M.; Fink, R.; Spindt, C.

    2002-01-01

    Charge neutralization of an In-FEEP thruster was demonstrated with three different electron sources by zeroing the floating potential of the thruster and neutralizer system. The three cathodes used in the investigation include a mixed metal thermionic cathode, a carbon nanotube field emission cathode, and a Spindt-type Mo field emission array cathode.

  11. Evaluation of low cost cathode materials for treatment of industrial and food processing wastewater using microbial electrolysis cells

    KAUST Repository

    Tenca, Alberto

    2013-02-01

    Microbial electrolysis cells (MECs) can be used to treat wastewater and produce hydrogen gas, but low cost cathode catalysts are needed to make this approach economical. Molybdenum disulfide (MoS2) and stainless steel (SS) were evaluated as alternative cathode catalysts to platinum (Pt) in terms of treatment efficiency and energy recovery using actual wastewaters. Two different types of wastewaters were examined, a methanol-rich industrial (IN) wastewater and a food processing (FP) wastewater. The use of the MoS2 catalyst generally resulted in better performance than the SS cathodes for both wastewaters, although the use of the Pt catalyst provided the best performance in terms of biogas production, current density, and TCOD removal. Overall, the wastewater composition was more of a factor than catalyst type for accomplishing overall treatment. The IN wastewater had higher biogas production rates (0.8-1.8 m3/m3-d), and COD removal rates (1.8-2.8 kg-COD/m3-d) than the FP wastewater. The overall energy recoveries were positive for the IN wastewater (3.1-3.8 kWh/kg-COD removed), while the FP wastewater required a net energy input of -0.7 - 1.2 kWh/kg-COD using MoS 2 or Pt cathodes, and -3.1 kWh/kg-COD with SS. These results suggest that MoS2 is the most suitable alternative to Pt as a cathode catalyst for wastewater treatment using MECs, but that net energy recovery will be highly dependent on the specific wastewater. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  12. Color Television Projection System Using Three Cathode Ray Tubes.

    Science.gov (United States)

    1982-03-01

    categories, specifically: light valves, scophony , lasers, liquid crystal modulation, and cathode ray tubes. Of these display techniques, the light valves 3...and have comparatively short life times associated with critical components. Both scophony and laser techniques utilize mechanical beam scanning

  13. Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells.

    Science.gov (United States)

    Nian, Li; Zhang, Wenqiang; Zhu, Na; Liu, Linlin; Xie, Zengqi; Wu, Hongbin; Würthner, Frank; Ma, Yuguang

    2015-06-10

    A highly photoconductive cathode interlayer was achieved by doping a 1 wt % light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10(-3) S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells.

  14. High Performance Fe-Co Based SOFC Cathodes

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent; Hansen, Karin Vels; Mogensen, Mogens Bjerg

    2010-01-01

    With the aim of reducing the temperature of the solid oxide fuel cell (SOFC), a new high-performance perovskite cathode has been developed. An area-specific resistance (ASR) as low as 0.12 Ωcm2 at 600 °C was measured by electrochemical impedance spectroscopy (EIS) on symmetrical cells. The cathode...... is a composite between (Gd0.6Sr0.4)0.99Fe0.8Co0.2O3-δ (GSFC) and Ce0.9Gd0.1O1.95 (CGO10). Examination of the microstructure of the cathodes by scanning electron microscopy (SEM) revealed a possibility of further optimisation of the microstructure in order to increase the performance of the cathodes. It also...

  15. Odyssey of Multivalent Cathode Materials: Open Questions and Future Challenges.

    Science.gov (United States)

    Canepa, Pieremanuele; Sai Gautam, Gopalakrishnan; Hannah, Daniel C; Malik, Rahul; Liu, Miao; Gallagher, Kevin G; Persson, Kristin A; Ceder, Gerbrand

    2017-03-08

    The rapidly expanding field of nonaqueous multivalent intercalation batteries offers a promising way to overcome safety, cost, and energy density limitations of state-of-the-art Li-ion battery technology. We present a critical and rigorous analysis of the increasing volume of multivalent battery research, focusing on a wide range of intercalation cathode materials and the mechanisms of multivalent ion insertion and migration within those frameworks. The present analysis covers a wide variety of material chemistries, including chalcogenides, oxides, and polyanions, highlighting merits and challenges of each class of materials as multivalent cathodes. The review underscores the overlap of experiments and theory, ranging from charting the design metrics useful for developing the next generation of MV-cathodes to targeted in-depth studies rationalizing complex experimental results. On the basis of our critical review of the literature, we provide suggestions for future multivalent cathode studies, including a strong emphasis on the unambiguous characterization of the intercalation mechanisms.

  16. A High Performance Cathode Heater for Hall Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High current hollow cathodes are the baseline electron source for next generation high power Hall thrusters. Currently for electron sources providing current levels...

  17. Intermetallics as cathode materials in the electrolytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Stojic, D.L.; Maksic, A.D.; Kaninski, M.P.M. [Vinca Inst. of Nuclear Sciences, Belgrade (Serbia and Montenegro). Lab. of Physical Chemistry; Cekic, B.D. [Vinca Inst. of Nuclear Sciences, Belgrade (Serbia and Montenegro). Lab. of Physics; Miljanic, S.S. [Belgrade Univ. (Serbia and Montenegro). Faculty of Physical Chemistry

    2005-01-01

    The intermetallics of transition metals have been investigated as cathode materials for the production of hydrogen by electrolysis from water-KOH solutions, in an attempt to increase the electrolytic process efficiency. We found that the best effect among all investigated cathodes (Hf{sub 2}Fe, Zr-Pt, Nb-Pd(I), Pd-Ta, Nb-Pd(II), Ti-Pt) exhibits the Hf{sub 2}Fe phase. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis. A significant upgrade of the electrolytic efficiency using intermetallics, either in pure KOH electrolyte or in combination with ionic activators added in situ, was achieved. The effects of these cathode materials on the process efficiency were discussed in the context of transition metal features that issue from their electronic configuration. (Author)

  18. NMR study of hydrogen in cathodically charged Inconel 718

    Energy Technology Data Exchange (ETDEWEB)

    Raizman, A.; Barak, J.; Zamir, D. (Israel Atomic Energy Commission, Yavne. Soreq Nuclear Research Center); Eliezer, D. (Ben-Gurion Univ. of the Negev, Beersheba (Israel))

    1983-11-01

    An NMR signal of protons in cathodically charged Inconel 718 has been detected. T/sub 1/, T/sub 2/, line shift and line width have been measured. Conclusions about hydrogen behavior in Inconel have been drawn.

  19. Cold cathode rf guns based study on field emission

    Directory of Open Access Journals (Sweden)

    Xiangkun Li

    2013-12-01

    Full Text Available Recently cold cathodes based on field emission have drawn attention and been considered to drive accelerators and free electron lasers, due to the progress in field emitter arrays and planar emitters like diamond films. In this paper, we reviewed the characteristics of field emission in rf fields. Simulations of S-band rf guns consisting of a cathode cell and a full cell were done. We showed that a shorter cathode cell with a length of 0.25–0.3 of λ/2 is in favor of obtaining both low emittance and low energy spread bunches when the amplitude of electric field on the cathode surface ranges from 60 to 80  MV/m. A single cell test cavity has been installed to study field emission of diamond films and the measured beam current showed a good agreement with theoretical calculations.

  20. Investigation of plasma flow in vacuum arc with hot cathode

    Science.gov (United States)

    Amirov, R.; Vorona, N.; Gavrikov, A.; Lizyakin, G.; Polistchook, V.; Samoylov, I.; Smirnov, V.; Usmanov, R.; Yartsev, I.

    2014-11-01

    One of the crucial problems which appear under development of plasma technology processing of spent nuclear fuel (SNF) is the design of plasma source. The plasma source must use solid SNF as a raw material. This article is devoted to experimental study of vacuum arc with hot cathode made of gadolinium that may consider as the simple model of SNF. This vacuum discharge was investigated in wide range of parameters. During the experiments arc current and voltage, cathode temperature, and heat flux to the cathode were measured. The data on plasma spectrum and electron temperature were obtained. It was shown that external heating of the cathode allows change significantly the main parameters of plasma. It was established by spectral and probe methods that plasma jet in studied discharge may completely consist of single charged ions.

  1. Scandate Cathode for High Power Long Life Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Scandate cathodes are proposed as a way to boost performance and life for electric space propulsion systems. This company has recently demonstrated breakthrough...

  2. Lithium sulfur batteries and electrolytes and sulfur cathodes thereof

    Science.gov (United States)

    Visco, Steven J.; Goncharenko, Nikolay; Nimon, Vitaliy; Petrov, Alexei; Nimon, Yevgeniy S.; De Jonghe, Lutgard C.; Katz, Bruce D.; Loginova, Valentina

    2017-05-23

    Lithium sulfur battery cells that use water as an electrolyte solvent provide significant cost reductions. Electrolytes for the battery cells may include water solvent for maintaining electroactive sulfur species in solution during cell discharge and a sufficient amount of a cycle life-enhancing compound that facilitates charging at the cathode. The combination of these two components enhances one or more of the following cell attributes: energy density, power density and cycle life. For instance, in applications where cost per Watt-Hour (Wh) is paramount, such as grid storage and traction applications, the use of an aqueous electrolyte in combination with inexpensive sulfur as the cathode active material can be a key enabler for the utility and automotive industries, for example, providing a cost effective and compact solution for load leveling, electric vehicles and renewable energy storage. Sulfur cathodes, and methods of fabricating lithium sulfur cells, in particular for loading lithium sulfide into the cathode structures, provide further advantages.

  3. Verification of high efficient broad beam cold cathode ion source

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Reheem, A. M., E-mail: amreheem2009@yahoo.com [Accelerators and Ion Sources Department, Nuclear Research Center, Atomic Energy Authority, P.N.13759, Cairo (Egypt); Radiation Physics Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Cairo (Egypt); Ahmed, M. M. [Physics Department, Faculty of Science, Helwan University, Cairo (Egypt); Abdelhamid, M. M.; Ashour, A. H. [Radiation Physics Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Cairo (Egypt)

    2016-08-15

    An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition.

  4. Lipon coatings for high voltage and high temperature Li-ion battery cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Dudney, Nancy J.; Liang, Chengdu; Nanda, Jagjit; Veith, Gabriel M.; Kim, Yoongu; Martha, Surendra Kumar

    2017-02-14

    A lithium ion battery includes an anode and a cathode. The cathode includes a lithium, manganese, nickel, and oxygen containing compound. An electrolyte is disposed between the anode and the cathode. A protective layer is deposited between the cathode and the electrolyte. The protective layer includes pure lithium phosphorus oxynitride and variations that include metal dopants such as Fe, Ti, Ni, V, Cr, Cu, and Co. A method for making a cathode and a method for operating a battery are also disclosed.

  5. Lipon coatings for high voltage and high temperature Li-ion battery cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Dudney, Nancy J.; Liang, Chengdu; Nanda, Jagjit; Veith, Gabriel M.; Kim, Yoongu; Martha, Surendra Kumar

    2017-12-05

    A lithium ion battery includes an anode and a cathode. The cathode includes a lithium, manganese, nickel, and oxygen containing compound. An electrolyte is disposed between the anode and the cathode. A protective layer is deposited between the cathode and the electrolyte. The protective layer includes pure lithium phosphorus oxynitride and variations that include metal dopants such as Fe, Ti, Ni, V, Cr, Cu, and Co. A method for making a cathode and a method for operating a battery are also disclosed.

  6. Cubic PdNP-based air-breathing cathodes integrated in glucose hybrid biofuel cells

    Science.gov (United States)

    Faggion Junior, D.; Haddad, R.; Giroud, F.; Holzinger, M.; Maduro de Campos, C. E.; Acuña, J. J. S.; Domingos, J. B.; Cosnier, S.

    2016-05-01

    Cubic Pd nanoparticles (PdNPs) were synthesized using ascorbic acid as a reducing agent and were evaluated for the catalytic oxygen reduction reaction. PdNPs were confined with multiwalled carbon nanotube (MWCNT) dispersions to form black suspensions and these inks were dropcast onto glassy carbon electrodes. Different nanoparticle sizes were synthesized and investigated upon oxygen reduction capacities (onset potential and electrocatalytic current densities) under O2 saturated conditions at varying pH values. Strong evidence of O2 diffusion limitation was demonstrated. In order to overcome oxygen concentration and diffusion limitations in solution, we used a gas diffusion layer to create a PdNP-based air-breathing cathode, which delivered -1.5 mA cm-2 at 0.0 V with an onset potential of 0.4 V. This air-breathing cathode was combined with a specially designed phenanthrolinequinone/glucose dehydrogenase-based anode to form a complete glucose/O2 hybrid bio-fuel cell providing an open circuit voltage of 0.554 V and delivering a maximal power output of 184 +/- 21 μW cm-2 at 0.19 V and pH 7.0.Cubic Pd nanoparticles (PdNPs) were synthesized using ascorbic acid as a reducing agent and were evaluated for the catalytic oxygen reduction reaction. PdNPs were confined with multiwalled carbon nanotube (MWCNT) dispersions to form black suspensions and these inks were dropcast onto glassy carbon electrodes. Different nanoparticle sizes were synthesized and investigated upon oxygen reduction capacities (onset potential and electrocatalytic current densities) under O2 saturated conditions at varying pH values. Strong evidence of O2 diffusion limitation was demonstrated. In order to overcome oxygen concentration and diffusion limitations in solution, we used a gas diffusion layer to create a PdNP-based air-breathing cathode, which delivered -1.5 mA cm-2 at 0.0 V with an onset potential of 0.4 V. This air-breathing cathode was combined with a specially designed phenanthrolinequinone

  7. High-performance lanthanum-ferrite-based cathode for SOFC

    DEFF Research Database (Denmark)

    Wang, W.G.; Mogensen, Mogens Bjerg

    2005-01-01

    (La0.6Sr0.4)(1-x)Co0.2Fe0.8O3/Ce0.9Gd0.1O3 (LSCF/CGO) composite cathodes were investigated for SOFC application at intermediate temperature, i.e., 500-700 degreesC. The LSCF/CGO cathodes have been studied on three types of tape-casted electrolyte substrates including CGO electrolyte, Yttrium-stab...

  8. Preparation of redox polymer cathodes for thin film rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    Skotheim, T.A.; Lee, H.S.; Okamoto, Yoshiyuki.

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  9. Single-layer graphene cathodes for organic photovoltaics

    Science.gov (United States)

    Cox, Marshall; Gorodetsky, Alon; Kim, Bumjung; Kim, Keun Soo; Jia, Zhang; Kim, Philip; Nuckolls, Colin; Kymissis, Ioannis

    2011-03-01

    A laminated single-layer graphene is demonstrated as a cathode for organic photovoltaic devices. The measured properties indicate that graphene offers two potential advantages over conventional photovoltaic electrode materials; work function matching via contact doping, and increased power conversion efficiency due to transparency. These findings indicate that flexible, light-weight all carbon solar cells can be constructed using graphene as the cathode material.

  10. Model for solid oxide fuel cell cathodes prepared by infiltration

    DEFF Research Database (Denmark)

    Samson, Alfred Junio; Søgaard, Martin; Hendriksen, Peter Vang

    2017-01-01

    A 1-dimensional model of a cathode has been developed in order to understand and predict the performance of cathodes prepared by infiltration of La0.6Sr0.4Co1.05O3-δ (LSC) into porous backbones of Ce0.9Gd0.1O1.95 (CGO). The model accounts for the mixed ionic and electronic conductivity of LSC, i...

  11. Cathodes for lithium-air battery cells with acid electrolytes

    Science.gov (United States)

    Xing, Yangchuan; Huang, Kan; Li, Yunfeng

    2016-07-19

    In various embodiments, the present disclosure provides a layered metal-air cathode for a metal-air battery. Generally, the layered metal-air cathode comprises an active catalyst layer, a transition layer bonded to the active catalyst layer, and a backing layer bonded to the transition layer such that the transition layer is disposed between the active catalyst layer and the backing layer.

  12. Chromium (V) compounds as cathode material in electrochemical power sources

    Science.gov (United States)

    Delnick, F.M.; Guidotti, R.A.; McCarthy, D.K.

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca/sub 5/(CrO/sub 4/)/sub 3/Cl, Ca/sub 5/(CrO/sub 4/)OH, and Cr/sub 2/O/sub 5/. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  13. Subzero-Temperature Cathode for a Sodium-Ion Battery.

    Science.gov (United States)

    You, Ya; Yao, Hu-Rong; Xin, Sen; Yin, Ya-Xia; Zuo, Tong-Tong; Yang, Chun-Peng; Guo, Yu-Guo; Cui, Yi; Wan, Li-Jun; Goodenough, John B

    2016-09-01

    A subzero-temperature cathode material is obtained by nucleating cubic prussian blue crystals at inhomogeneities in carbon nanotubes. Due to fast ionic/electronic transport kinetics even at -25 °C, the cathode shows an outstanding low-temperature performance in terms of specific energy, high-rate capability, and cycle life, providing a practical sodium-ion battery powering an electric vehicle in frigid regions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Investigation on multi-frequency oscillations in InGaAs planar Gunn diode with multiple anode-cathode spacings

    Science.gov (United States)

    Li, B.; Alimi, Y.; Ma, G. L.

    2016-12-01

    Current oscillations in an AlGaAs/InGaAs/AlGaAs-based two-dimensional electron gas (2DEG)-based hetero-structure have been investigated by means of semiconductor device simulation software SILVACO, with an interest on the charge domain formation at large biases. Single-frequency oscillations are generated in planar Gunn diodes with uniform anode and cathode contacts. The oscillation frequency reduces as the applied bias voltage increases. We show that it is possible to create multiple, independent charge domains in a novel Gunn diode structure with designed multiple anode-cathode spacings. This enables simultaneous generation of multiple frequency oscillations in a single planar device, in contrast to traditional vertical Gunn diodes where only single-frequency oscillations can be achieved. More interestingly, frequency mixing in multiple-channel configured Gunn diodes appeared. This proof-of-concept opens up the possibility for realizing compact self-oscillating mixer at millimeter-wave applications.

  15. Testing Iodine as a New Fuel for Cathodes

    Science.gov (United States)

    Glad, Harley; Branam, Richard; Rogers, Jim; Warren, Matthew; Burleson, Connor; Siy, Grace

    2017-11-01

    The objective of this research is to demonstrate the viability of using iodine as an alternative space propulsion propellant. The demonstration requires the testing of a cathode with xenon and then the desired element iodine. Currently, cathodes run on noble gases such as xenon which must be stored in high pressure canisters and is very expensive. These shortcomings have led to researching possible substitutes. Iodine was decided as a suitable candidate because it's cheaper, can be stored as a solid, and has similar mass properties as xenon. In this research, cathodes will be placed in a vacuum chamber and operated on both gases to observe their performance, allowing us to gain a better understanding of iodine's behavior. Several planned projects depend on the knowledge gained from this project, such as larger scaled tests and iodine fed hall thrusters. The tasks of this project included protecting the stainless-steel vacuum chamber by gold plating and Teflon® coating, building a stand to hold the cathode, creating an anode resistant to iodine, and testing the cathode once setup was complete. The successful operation of the cathode was demonstrated. However, the experimental setup proved ineffective at controlling the iodine flow. Current efforts are focused on this problem. REU Site: Fluid Mechanics with Analysis using Computations and Experiments NSF Grant EEC 1659710.

  16. Hollow cathode heater development for the Space Station plasma contactor

    Science.gov (United States)

    Soulas, George C.

    1993-01-01

    A hollow cathode-based plasma contactor has been selected for use on the Space Station. During the operation of the plasma contactor, the hollow cathode heater will endure approximately 12000 thermal cycles. Since a hollow cathode heater failure would result in a plasma contactor failure, a hollow cathode heater development program was established to produce a reliable heater design. The development program includes the heater design, process documents for both heater fabrication and assembly, and heater testing. The heater design was a modification of a sheathed ion thruster cathode heater. Three heaters have been tested to date using direct current power supplies. Performance testing was conducted to determine input current and power requirements for achieving activation and ignition temperatures, single unit operational repeatability, and unit-to-unit operational repeatability. Comparisons of performance testing data at the ignition input current level for the three heaters show the unit-to-unit repeatability of input power and tube temperature near the cathode tip to be within 3.5 W and 44 degrees C, respectively. Cyclic testing was then conducted to evaluate reliability under thermal cycling. The first heater, although damaged during assembly, completed 5985 ignition cycles before failing. Two additional heaters were subsequently fabricated and have completed 3178 cycles to date in an on-going test.

  17. An adjustable electron achromat for cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-12-15

    Chromatic aberration correction in light optics began with the invention of a two-color-corrected achromatic crown/flint lens doublet by Chester Moore Hall in 1730. Such color correction is necessary because any single glass shows dispersion (i.e. its index of refraction changes with wavelength), which can be counteracted by combining different glasses with different dispersions. In cathode lens microscopes (such as Photo Electron Emission Microscopy – PEEM) we encounter a similar situation, where the chromatic aberration coefficient of the cathode lens shows strong dispersion, i.e. depends (non-linearly) on the energy with which the electrons leave the sample. Here I show how a cathode lens in combination with an electron mirror can be configured as an adjustable electron achromat. The lens/mirror combination can be corrected at two electron energies by balancing the settings of the electron mirror against the settings of the cathode lens. The achromat can be adjusted to deliver optimum performance, depending on the requirements of a specific experiment. Going beyond the achromat, an apochromat would improve resolution and transmission by a very significant margin. I discuss the requirements and outlook for such a system, which for now remains a wish waiting for fulfilment. - Highlights: • The properties of cathode objective lens plus electron mirror are discussed. • In analogy with light-optical achromats, cathode lens plus mirror can be configured as an electron achromat. • Unlike light optics, the electron achromat can be adjusted to best fulfill experimental requirements.

  18. Dynamic Aspects of Solid Solution Cathodes for Electrochemical Power Sources

    DEFF Research Database (Denmark)

    Atlung, Sven; West, Keld; Jacobsen, Torben

    1979-01-01

    Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice,"show considerable promise for high energy density storage batteries. Thispaper discusses the interaction between battery requirements, in particu......Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice,"show considerable promise for high energy density storage batteries. Thispaper discusses the interaction between battery requirements......, in particularfor vehicle propulsion, and electrochemical and constructional factors. It isargued that the energy obtainable at a given load is limited by saturation ofthe surface layers of cathode particles with cations, and that the time beforesaturation occurs is determined by diffusion of cations and electrons...... into thehost lattice. Expressions are developed for plane, cylindrical, and sphericalparticles, giving the relation between battery load and the amount of cathodematerial utilized before saturation. The particle shape and a single parameterQ is used to describe cathode performance. Q is the ratio between...

  19. Cathodic protection for the bottoms of above ground storage tanks

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, John P. [Tyco Adhesives, Norwood, MA (United States)

    2004-07-01

    Impressed Current Cathodic Protection has been used for many years to protect the external bottoms of above ground storage tanks. The use of a vertical deep ground bed often treated several bare steel tank bottoms by broadcasting current over a wide area. Environmental concerns and, in some countries, government regulations, have introduced the use of dielectric secondary containment liners. The dielectric liner does not allow the protective cathodic protection current to pass and causes corrosion to continue on the newly placed tank bottom. In existing tank bottoms where inadequate protection has been provided, leaks can develop. In one method of remediation, an old bottom is covered with sand and a double bottom is welded above the leaking bottom. The new bottom is welded very close to the old bottom, thus shielding the traditional cathodic protection from protecting the new bottom. These double bottoms often employ the use of dielectric liner as well. Both the liner and the double bottom often minimize the distance from the external tank bottom. The minimized space between the liner, or double bottom, and the bottom to be protected places a challenge in providing current distribution in cathodic protection systems. This study examines the practical concerns for application of impressed current cathodic protection and the types of anode materials used in these specific applications. One unique approach for an economical treatment using a conductive polymer cathodic protection method is presented. (author)

  20. Lithium Iron Orthosilicate Cathode: Progress and Perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Jiangfeng [College; amp, Physics (CECMP), Soochow University, Suzhou 215006, PR China; Jiang, Yu [College; amp, Physics (CECMP), Soochow University, Suzhou 215006, PR China; Bi, Xuanxuan [Chemical; Li, Liang [College; amp, Physics (CECMP), Soochow University, Suzhou 215006, PR China; Lu, Jun [Chemical

    2017-07-18

    The pursuit of cathodes with a high capacity is remarkably driven by the ever increasing demand of high-energy lithium ion batteries in electronics and transportation. In this regard, polyanionic lithium iron orthosilicate (Li2FeSiO4) offers a promising opportunity because it affords a high theoretical capacity of 331 mAh g–1. However, such a high theoretical capacity of Li2FeSiO4 has frequently been compromised in practice because of the extremely low electronic and ionic conductivity. To address this issue, material engineering strategies to boost the Li storage kinetics in Li2FeSiO4 have proven indispensable. In this Perspective, we will briefly present the structural characteristics, intrinsic physicochemical properties, and electrochemical behavior of Li2FeSiO4. We particularly focus on recent materials engineering of silicates, which is implemented mainly through advanced synthetic techniques and elaborate controls. This Perspective highlights the importance of integrating theoretical analysis into experimental implementation to further advance the Li2FeSiO4 materials.

  1. Performance and Structural Evolution of Nano-Scale Infiltrated Solid Oxide Fuel Cell Cathodes

    Science.gov (United States)

    Call, Ann Virginia

    Nano-structured mixed ionic and electronic conducting (MIEC) materials have garnered intense interest in electrode development for solid oxide fuel cells due to their high surface areas which allow for effective catalytic activity and low polarization resistances. In particular, composite solid oxide fuel cell (SOFC) cathodes consisting of ionic conducting scaffolds infiltrated with MIEC nanoparticles have exhibited some of the lowest reported polarization resistances. In order for cells utilizing nanostructured moRPhologies to be viable for commercial implementation, more information on their initial performance and long term stability is necessary. In this study, symmetric cell cathodes were prepared via wet infiltration of Sr0.5Sm 0.5CoO3 (SSC) nano-particles via a nitrate process into porous Ce0.9Gd0.1O1.95 (GDC) scaffolds to be used as a model system to investigate performance and structural evolution. Detailed analysis of the cells and cathodes was carried out using electrochemical impedance spectroscopy (EIS). Initial polarization resistances (RP) as low as 0.11 O cm2 at 600ºC were obtained for these SSC-GDC cathodes, making them an ideal candidate for studying high performance nano-structured electrodes. The present results show that the infiltrated cathode microstructure has a direct impact on the initial performance of the cell. Small initial particle sizes and high infiltration loadings (up to 30 vol% SSC) improved initial RP. A simple microstructure-based electrochemical model successfully explained these trends in RP. Further understanding of electrode performance was gleaned from fitting EIS data gathered under varying temperatures and oxygen partial pressures to equivalent circuit models. Both RQ and Gerischer impedance elements provided good fits to the main response in the EIS data, which was associated with the combination of oxygen surface exchange and oxygen diffusion in the electrode. A gas diffusion response was also observed at relatively

  2. Correlation between hydrogen production rate, current, and electrode overpotential in a solid oxide electrolysis cell with La0.6Sr0.4FeO3-δ thin-film cathode.

    Science.gov (United States)

    Walch, Gregor; Opitz, Alexander Karl; Kogler, Sandra; Fleig, Jürgen

    A solid oxide electrolysis cell (SOEC) with a model-type La0.6Sr0.4FeO3-δ thin-film cathode (working electrode) on an yttria-stabilized zirconia electrolyte and a porous La0.6Sr0.4Co0.2Fe0.8O3-δ counterelectrode was operated in wet argon gas at the cathode. The hydrogen formation rate in the cathode compartment was quantified by mass spectrometry. Determination of the current as well as outlet gas composition revealed the electrochemical reduction of some residual oxygen in the cathodic compartment. Quantitative correlation between gas composition changes and current flow was possible. At 640 °C a water-to-hydrogen conversion rate of ca. 4 % was found at -1.5 V versus a reversible counterelectrode in 1 % oxygen. Onset of hydrogen formation could already be detected at voltages as low as -0.3 V. This reflects a fundamental difference between steam electrolysis and electrolysis of liquid water: substantial hydrogen production in a SOEC is already possible at pressures much below ambient. This causes difficulties in determining the cathodic overpotential of such a cell.

  3. Feedback model of secondary electron emission in DC gas discharge plasmas

    Science.gov (United States)

    Saravanan, ARUMUGAM; Prince, ALEX; Suraj, Kumar SINHA

    2018-01-01

    Feedback is said to exist in any amplifier when the fraction of output power in fed back as an input. Similarly, in gaseous discharge ions that incident on the cathode act as a natural feedback element to stabilize and self sustain the discharge. The present investigation is intended to emphasize the feedback nature of ions that emits secondary electrons (SEs) from the cathode surface in DC gas discharges. The average number of SEs emitted per incident ion and non ionic species (energetic neutrals, metastables and photons) which results from ion is defined as effective secondary electron emission coefficient (ESEEC,{γ }{{E}}). In this study, we derive an analytic expression that corroborates the relation between {γ }{{E}} and power influx by ion to the cathode based on the feedback theory of an amplifier. In addition, experimentally, we confirmed the typical positive feedback nature of SEE from the cathode in argon DC glow discharges. The experiment is done for three different cathode material of same dimension (tungsten (W), copper (Cu) and brass) under identical discharge conditions (pressure: 0.45 mbar, cathode bias: ‑600 V, discharge gab: 15 cm and operating gas: argon). Further, we found that the {γ }{{E}} value of these cathode material controls the amount of feedback power given by ions. The difference in feedback leads different final output i.e the power carried by ion at cathode ({P}{{i}}{\\prime }{| }{{C}}). The experimentally obtained value of {P}{{i}}{\\prime }{| }{{C}} is 4.28 W, 6.87 W and 9.26 W respectively for W, Cu and brass. In addition, the present investigation reveals that the amount of feedback power in a DC gas discharges not only affect the fraction of power fed back to the cathode but also the entire characteristics of the discharge.

  4. Tungsten and Barium Transport in the Internal Plasma of Hollow Cathodes

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2008-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushedback to the emitter surface by the electric field and drag from the xenon ion flow. Thisbarium ion flux is sufficient to maintain a barium surface coverage at the downstream endgreater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length,so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollowcathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  5. Evaluación de un sistema de humidificación de hoja de tabaco por nebulización Evaluating a tobacco leaf humidification system involving nebulisation

    Directory of Open Access Journals (Sweden)

    Pastrana Bonilla Eduardo

    2010-08-01

    Full Text Available Se diseñó, implementó y evaluó un sistema de humidificación por nebulización para la hoja de tabaco, que cuenta con un sistema para el control y el registro de las condiciones ambientales del recinto, lo que permite generar un ambiente con humedad relativa más homogénea, logrando un mejor uso del agua y mayor control en la humedad relativa y en el manejo del contenido de humedad de la hoja de tabaco curada, con la consiguiente mejora en la calidad del producto a comercializar. Se obtuvieron rangos de trabajo de humedad relativa entre el 55 y el 75%, y tiempos de 4 a 6 horas para alcanzar la rehumidificación de la hoja hasta el 16%, en base húmeda. Con base en los resultados obtenidos y las observaciones hechas en campo, en cuanto al manejo operativo de este recinto, se propusieron dos nuevos diseños pa- ra el sistema de humidificación que permitirían un mejor manejo de la hoja reduciendo las pérdidas por manipulación y sobrehumedecimiento. Este trabajo fortalece el proceso de investigación en el área de la poscosecha de tabaco, al complementar otros proyectos de investigación al respecto, que se han realizado en Colombia.A tobacco leaf humidifying system involving nebulisation was designned, implemented and evaluated; it had a system for monitoring and recording environmental conditions thereby producing an environment having more homogeneous relative humidity, ensuring better water use, better control of relative humidity and better control in managing cured tobacco leaf moisture content, thereby leading to a consequent improvement in final product quality. 55% to 75% relative humidity and 4 to 6 hour working ranges were obtained to en- sure leaf humidification reached 16% humidity on a wet basis. Two new designs are proposed for the conditioning stage regarding this conditioning chamber’s operational management, based on the results and field observations, which would allow better leaf management, thereby avoiding the risk

  6. Fundamental mechanisms in flue gas conditioning. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, T.R.; Bush, P.V.; Dahlin, R.S.

    1996-03-20

    The US Department of Energy`s Pittsburgh Energy Technology Center (DOE/PETC) initiated this project as part of a program to study the control of fine particles from coal combustion. Our project focus was flue gas conditioning. Various conditioning processes have lowered operating costs and increased collection efficiency at utility particulate control devices. By improving fine particle collection, flue gas conditioning also helps to control the emission of toxic metals, which are concentrated in the fine particle fraction. By combining a review of pertinent literature, laboratory characterization of a variety of fine powders and ashes, pilot-scale studies of conditioning mechanisms, and field experiences, Southern Research Institute has been able to describe many of the key processes that account for the effects that conditioning can have on fine-particle collection. The overall goal of this research project was to explain the mechanisms by which various flue gas conditioning processes alter the performance of particulate control devices. Conditioning involves the modification of one or more of the parameters that determine the magnitude of the forces acting on the fly ash particles. Resistivity, chemistry, cohesivity, size distribution, and particle morphology are among the basic properties of fly ash that significantly influence fine particle collection. Modifications of particulate properties can result in improved or degraded control device performance. These modifications can be caused by (1) changes to the process design or operation that affect properties of the flue gas, (2) addition of particulate matter such as flue-gas desulfurization sorbents to the process effluent stream, (3) injection of reactive gases or liquids into the flue gas. We recommend that humidification be seriously considered as a flue gas conditioning option. 80 refs., 69 figs., 23 tabs.

  7. Copper current collectors reduce long-term fouling of air cathodes in microbial fuel cells

    KAUST Repository

    Myung, Jaewook

    2018-02-05

    Long-term operation of wastewater-fed, microbial fuel cells (MFCs) with cathodes made of activated carbon and stainless steel (SS) current collectors can result in decreased performance due to cathode fouling. Copper has good antimicrobial properties, and it is more electrically conductive than SS. To demonstrate that a copper current collector could produce a more fouling resistant cathode, MFCs with air cathodes using either SS or copper current collectors were operated using domestic wastewater for 27 weeks. The reduction in biofouling over time was shown by less biofilm formation on the copper cathode surface compared to SS cathodes, due to the antimicrobial properties of copper. Maximum power densities from 17–27 weeks were 440 ± 38 mW/m2 using copper and 370 ± 21 mW/m2 using SS cathodes. The main difference in the microbial community was a nitrifying community on the SS cathodes, which was not present on the copper cathodes.

  8. Control of vacuum arc source cathode spots contraction motion by changing electromagnetic field

    Science.gov (United States)

    Xin, SONG; Qing, WANG; Zeng, LIN; Puhui, ZHANG; Shuhao, WANG

    2018-02-01

    This paper investigates the magnetic field component impact on cathode spots motion trajectory and the mechanism of periodic contraction. Electromagnetic coils and permanent magnets were installed at the different sides of cathode surface, the photographs of cathode spots motion trajectory were captured by a camera. Increasing the number of magnets and decreasing the distance between magnets and cathode both lead to enhancing cathode spots motion velocity. Radii of cathode spots trajectory decrease gradually with the increasing of electromagnetic coil’s current, from 40 mm at 0 A to 10 mm at 2.7 A. Parallel magnetic field component intensity influence the speed of cathode spots rotate motion, and perpendicular magnetic field component drives spots drift in the radial direction. Cathode spot’s radial drift is controlled by changing the location of the ‘zero line’ where perpendicular magnetic component shifts direction and the radius of cathode spots trajectory almost equal to ‘zero line’.

  9. Ion exchange membrane cathodes for scalable microbial fuel cells.

    Science.gov (United States)

    Zuo, Yi; Cheng, Shaoan; Logan, Bruce E

    2008-09-15

    One of the main challenges for using microbial fuel cells (MFCs) is developing materials and architectures that are economical and generate high power densities. The performance of two cathodes constructed from two low-cost anion (AEM) and cation (CEM) exchange membranes was compared to that achieved using an ultrafiltration (UF) cathode, when the membranes were made electrically conductive using graphite paint and a nonprecious metal catalyst (CoTMPP). The best performance in single-chamber MFCs using graphite fiber brush anodes was achieved using an AEM cathode with the conductive coating facing the solution, at a catalyst loading of 0.5 mg/cm2 CoTMPP. The maximum power densitywas 449 mW/ m2 (normalized to the projected cathode surface area) or 13.1 W/m3 (total reactor volume), with a Coulombic efficiency up to 70% in a 50 mM phosphate buffer solution (PBS) using acetate. Decreasing the CoTMPP loading by 40-80% reduced power by 28-56%, with only 16% of the power (72 mW/m2) generated using an AEM cathode lacking a catalyst. Using a current collector (a stainless steel mesh) pressed against the inside surface of the AEM cathode and 200 mM PBS, the maximum power produced was further increased to 728 mW/m2 (21.2 W/m3). The use of AEM cathodes and brush anodes provides comparable performance to similar systems that use materials costing nearly an order of magnitude more (carbon paper electrodes) and thus represent more useful materials for reducing the costs of MFCs for wastewater treatment applications.

  10. reaction process simulation of hydrogen gas discharge in a cold ...

    Indian Academy of Sciences (India)

    In the cold cathode electric vacuum device, under low pressure and weak ionization, elastic collision reaction is encountered by most electrons, that is, e + H2 → H2 + e and e + H → H + e, but the inelastic collision is the key method for ionizing the working gas and constituting plasma [10]. The inelastic collision has four ...

  11. Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies

    Science.gov (United States)

    Saini, V. K.; Kumar, P.; Sarangpani, K. K.; Dixit, S. K.; Nakhe, S. V.

    2017-09-01

    Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine (2S1/2 → 2P1/2, 3/2) transitions. These OG transitions allow 0.33 cm-1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.

  12. Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies.

    Science.gov (United States)

    Saini, V K; Kumar, P; Sarangpani, K K; Dixit, S K; Nakhe, S V

    2017-09-01

    Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine (2S1/2 → 2P1/2, 3/2) transitions. These OG transitions allow 0.33 cm-1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.

  13. Inert Anode/Cathode Program: Fiscal Year 1986 annual report. [For Hall-Heroult cells

    Energy Technology Data Exchange (ETDEWEB)

    Brenden, B.B.; Davis, N.C.; Koski, O.H.; Marschman, S.C.; Pool, K.H.; Schilling, C.H.; Windisch, C.F.; Wrona, B.J.

    1987-06-01

    Purpose of the program is to develop long-lasting, energy-efficient anodes, cathodes, and ancillary equipment for Hall-Heroult cells used by the aluminum industry. The program is divided into four tasks: Inert Anode Development, Cathode Materials Evaluation, Cathode Bonding Development, and Sensor Development. To devise sensors to control the chemistry of Hall-Heroult cells using stable anodes and cathodes. This report highlights the major FY86 technical accomplishments, which are presented in the following sections: Management, Materials Development, Materials Evaluation, Thermodynamic Evaluation, Laboratory Cell Tests, Large-Scale Tests, Cathode Materials Evaluation, Cathode Bonding Development, and Sensor Development.

  14. Chromium poisoning of LSM/YSZ and LSCF/CGO composite cathodes

    DEFF Research Database (Denmark)

    Bentzen, Janet Jonna; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

    2009-01-01

    An electrochemical study of SOFC cathode degradation, due to poisoning by chromium oxide vapours, was performed applying 3-electrode set-ups. The cathode materials comprised LSM/YSZ and LSCF/CGO composites, whereas the electrolyte material was 8YSZ. The degradation of the cathode performance...... from 300 to 2,970 h. Both LSM/YSZ and LSCF/CGO cathodes were sensitive to chromium poisoning; LSCF/CGO cathodes to a lesser extent than LSM/YSZ. Humid air aggravated the degradation of the cathode performance. Post-mortem electron microscopic investigations revealed several Cr-containing compounds...

  15. METHOD AND APPARATUS FOR PRODUCING INTENSE ENERGETIC GAS DISCHARGES

    Science.gov (United States)

    Bell, P.R.; Luce, J.S.

    1960-01-01

    A device for producing an energetic gas arc discharge employing the use of gas-fed hollow cathode and anode electrodes is reported. The rate of feed of the gas to the electrodes is regulated to cause complete space charge neutralization to occur within the electrodes. The arc discharge is closely fitted within at least one of the electrodes so tint the gas fed to this electrode is substantially completely ionized before it is emitted into the vacuum chamber. It is this electrode design and the axial potential gradient that exists in the arc which permits the arc to be operated in low pressures and at volthges and currents that permit the arc to be energetic. The use of the large number of energetic ions that are accelerated toward the cathode as a propulsion device for a space vehicle is set forth.

  16. Electron and ion kinetics in a micro hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G J; Iza, F; Lee, J K [Electronics and Electrical Engineering Department, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2006-10-21

    Electron and ion kinetics in a micro hollow cathode discharge are investigated by means of two-dimensional axisymmetric particle-in-cell Monte Carlo collision simulations. Argon discharges at 10 and 300 Torr are studied for various driving currents. Electron and ion energy probability functions (IEPF) are shown at various times and locations to study the spatio-temporal behaviour of the discharge. The electron energy probability function (EEPF) evolves from the Druyvesteyn type in the early stages of the discharge into a two (or three) temperature distribution when steady state is reached. In steady state, secondary electrons accelerated across the cathode fall populate the high energy tail of the EEPF while the low energy region is populated by trapped electrons. The IEPF evolves from a Maxwellian in the negative glow (bulk) to a two temperature distribution on the cathode surface. The overpopulation of low energy ions near the cathode surface is attributed to a larger collision cross section for low energy ions and ionization within the cathode fall.

  17. An activated carbon fiber cathode for the degradation of glyphosate in aqueous solutions by the Electro-Fenton mode: Optimal operational conditions and the deposition of iron on cathode on electrode reusability.

    Science.gov (United States)

    Lan, Huachun; He, Wenjing; Wang, Aimin; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui; Huang, C P

    2016-11-15

    An activated carbon fiber (ACF) cathode was fabricated and used to treat glyphosate containing wastewater by the Electro-Fenton (EF) process. The results showed that glyphosate was rapidly and efficiently degraded and the BOD5/COD ratio was increased to >0.3 implying the feasibility of subsequent treatment of the treated wastewater by biological methods. The results of ion chromatography and HPLC measurements indicated that glyphosate was completely decomposed. Effective OH generation and rapid recycling/recovery of the Fe(2+) ions at the cathode were responsible primarily for the high performance of the ACF-EF process. Factors such as inlet oxygen gas flow rate, Fe(2+) dosage, initial glyphosate concentration, applied current intensity, and solution pH that may affect the efficiency of the ACF-EF process were further studied and the optimum operation condition was established. Results of SEM/EDX, BET and XPS analysis showed the deposition of highly dispersed fine Fe2O3 particles on the ACF surface during the EF reaction. The possibility of using the Fe2O3-ACF as iron source in the EF process was assessed. Results showed that the Fe2O3-ACF electrode was effective in degrading glyphosate in the EF process. The deposition of Fe2O3 particles on the ACF electrode had no adverse effect on the reusability of the ACF cathode. Copyright © 2016. Published by Elsevier Ltd.

  18. A quantum chemical cluster study of hydrated halide adsorption on the cathodic Al(111) surface

    Science.gov (United States)

    Kairys, Visvaldas; Head, John D.

    1999-10-01

    Ab-initio cluster calculations are used to simulate water, fluorine and iodine adsorption on a negatively charged Al(111) surface. In contrast to our earlier work using neutral Al clusters, we determine the water to be only weakly adsorbed above the negatively charged Al clusters, with the water H atoms being closest to the metal surface. A H-bond network is readily formed when more than one water molecule is adsorbed on the Al cluster surface. Analogous to the recent in-situ surface X-ray scattering experiments on Ag(111) surfaces, we find the separation between the water and the cathodic surface to be approximately 1.5 times greater than that found previously for the neutral Al(111) surface. In addition, there is a strong repulsion preventing the water molecules from being closer than 3.0 Å to the negatively charged surface. For the halides, in line with gas-phase adsorption experiments and other calculations, we find that fluorine is much more strongly bound to the Al clusters than iodine, with the Al(111) atop site being the most favored surface site for both halides. By performing calculations on Al clusters with a halide ion and one or more water molecules coadsorbed, we are able to develop an explanation as to why solvated iodine is more readily able to specifically adsorb on a cathodic surface than fluorine. The larger atomic size of iodine enables it to adsorb on the cathodic Al(111) surface at a higher vertical height than fluorine. Water molecules can then bond to iodine without being drawn into the region of repulsive interaction from the negatively charged surface. Thus we find the adsorption energy for I -·(H 2O) 3 adsorbed on Al -19 to be very similar to the I - adsorption energy, suggesting that iodine can be specifically adsorbed on the cathodic Al(111) surface without destabilizing any coadsorbed water molecules, whereas any water molecules hydrogen-bonding to fluorine are pulled towards the Al(111) surface and destabilized when the fluorine

  19. High performance and durability of order-structured cathode catalyst layer based on TiO2@PANI core-shell nanowire arrays

    Science.gov (United States)

    Chen, Ming; Wang, Meng; Yang, Zhaoyi; Wang, Xindong

    2017-06-01

    In this paper, an order-structured cathode catalyst layer consisting of Pt-TiO2@PANI core-shell nanowire arrays that in situ grown on commercial gas diffusion layer (GDL) are prepared and applied to membrane electrode assembly (MEA) of proton exchange membrane fuel cell (PEMFC). In order to prepare the TiO2@PANI core-shell nanowire arrays with suitable porosity and prominent conductivity, the morphologies of the TiO2 nanoarray and electrochemical polymerization process of aniline are schematically investigated. The MEA with order-structured cathode catalyst layer is assembled in the single cell to evaluate the electrochemical performance and durability of PEMFC. As a result, the PEMFC with order-structured cathode catalyst layer shows higher peak power density (773.54 mW cm-2) than conventional PEMFC (699.30 mW cm-2). Electrochemically active surface area (ECSA) and charge transfer impedance (Rct) are measured before and after accelerated degradation test (ADT), and the corresponding experimental results indicate the novel cathode structure exhibits a better stability with respect to conventional cathode. The enhanced electrochemical performance and durability toward PEMFC can be ascribed to the order-structured cathode nanoarray structure with high specific surface area increases the utilization of catalyst and reduces the tortuosity of transport pathways, and the synergistic effect between TiO2@PANI support and Pt nanoparticles promotes the high efficiency of electrochemical reaction and improves the stability of catalyst. This research provides a facile and controllable method to prepare order-structured membrane electrode with lower Pt loading for PEMFC in the future.

  20. Enhanced Electro-Fenton Mineralization of Acid Orange 7 Using a Carbon Nanotube Fiber-Based Cathode

    Directory of Open Access Journals (Sweden)

    Thi Xuan Huong Le

    2018-02-01

    Full Text Available A new cathodic material for electro-Fenton (EF process was prepared based on a macroscopic fiber (CNTF made of mm-long carbon nanotubes directly spun from the gas phase by floating catalyst CVD, on a carbon fiber (CF substrate. CNTF@CF electrode is a highly graphitic material combining a high surface area (~260 m2/g with high electrical conductivity and electrochemical stability. One kind of azo dye, acid orange 7 (AO7, was used as model bio-refractory pollutant to be treated at CNTF@CF cathode in acidic aqueous medium (pH 3.0. The experimental results pointed out that AO7 and its organic intermediate compounds were totally mineralized by hydroxyl radical generated from Fenton reaction. In fact, 96.7% of the initial total organic carbon (TOC was eliminated in 8 h of electrolysis by applying a current of −25 mA and ferrous ions as catalyst at concentration of 0.2 mM. At the same electrolysis time, only 23.7% of TOC removal found on CF support which proved the high mineralization efficiency of new material thanks to CNTF deposition. The CNTF@CF cathode maintained stable its activity during five experimental cycles of EF setup. The results indicated that CNTF@CF material could be a potential choice for wastewater treatment containing bio-refractory by electrochemical advanced oxidation processes.

  1. Non-Aqueous Primary Li-Air Flow Battery and Optimization of its Cathode through Experiment and Modeling.

    Science.gov (United States)

    Kim, Byoungsu; Takechi, Kensuke; Ma, Sichao; Verma, Sumit; Fu, Shiqi; Desai, Amit; Pawate, Ashtamurthy S; Mizuno, Fuminori; Kenis, Paul J A

    2017-09-22

    A primary Li-air battery has been developed with a flowing Li-ion free ionic liquid as the recyclable electrolyte, boosting power capability by promoting superoxide diffusion and enhancing discharge capacity through separately stored discharge products. Experimental and computational tools are used to analyze the cathode properties, leading to a set of parameters that improve the discharge current density of the non-aqueous Li-air flow battery. The structure and configuration of the cathode gas diffusion layers (GDLs) are systematically modified by using different levels of hot pressing and the presence or absence of a microporous layer (MPL). These experiments reveal that the use of thinner but denser MPLs is key for performance optimization; indeed, this leads to an improvement in discharge current density. Also, computational results indicate that the extent of electrolyte immersion and porosity of the cathode can be optimized to achieve higher current density. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Study of an unitised bidirectional vanadium/air redox flow battery comprising a two-layered cathode

    Science.gov (United States)

    grosse Austing, Jan; Nunes Kirchner, Carolina; Hammer, Eva-Maria; Komsiyska, Lidiya; Wittstock, Gunther

    2015-01-01

    The performance of a unitised bidirectional vanadium/air redox flow battery (VARFB) is described. It contains a two-layered cathode consisting of a gas diffusion electrode (GDE) with Pt/C catalyst for discharging and of an IrO2 modified graphite felt for charging. A simple routine is shown for the modification of a graphite felt with IrO2. A maximum energy efficiency of 41.7% at a current density of 20 mA cm-2 as well as an average discharge power density of 34.6 mW cm-2 at 40 mA cm-2 were obtained for VARFB operation at room temperature with the novel cathode setup. A dynamic hydrogen electrode was used to monitor half cell potentials during operation allowing to quantify the contribution of the cathode to the overall performance of the VARFB. Four consecutive cycles revealed that crossover of vanadium ions took place and irreversible degradation processes within the reaction unit lead to a performance decrease.

  3. 81.114- University Reactor Infrastructure and Education Support / Prompt Gamma-ray Activation Analysis of Lithioum Ion Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Manthiram, Arumugam; Landsberger, S.

    2006-11-11

    This project focuses on the use of the Prompt Gamma-ray Activation Analysis (PGAA) technique available at the Nuclear Engineering Teaching Laboratory of the University of Texas at Austin to precisely determine the hydrogen (proton) contents in layered oxide cathode samples obtained by chemical lithium extraction in order to obtain a better understanding of the factors limiting the practical capacities and overall performance of lithium ion battery cathodes. The project takes careful precautionary experimental measures to avoid proton contamination both from solvents used in chemical delithiation and from ambient moisture. The results obtained from PGAA are complemented by the data obtained from other techniques such as thermogravimetric analysis, redox titration, atomic absorption spectroscopy, X-ray diffraction, and mass spectroscopic analysis of the evolved gas on heating. The research results broaden our understanding of the structure-property-performance relationships of lithium ion battery cathodes and could aid the design and development of new better performing lithium ion batteries for consumer (portable and electric vehicles), military, and space applications.

  4. A 13000-hour test of a mercury hollow cathode

    Science.gov (United States)

    Rawlin, V. K.

    1973-01-01

    A mercury-fed hollow cathode was tested for 12,979 hours in a bell jar at SERT 2 neutralizer operating conditions. The net electron current drawn to a collector was 0.25 ampere at average collector voltages between 21.8 and 36.7 volts. The mercury flow rate was varied from 5.6 to 30.8 equivalent milliamperes to give stable operation at the desired electrode voltages and currents. Variations with time in the neutralizer discharge characteristics were observed and hypothesized to be related to changes in the cathode orifice dimensions and the availability of electron emissive material. A facility failure caused abnormal test conditions for the last 876 hours and led to the cathode heater failure which concluded the test.

  5. Characteristic of a triple-cathode vacuum arc plasma source.

    Science.gov (United States)

    Xiang, W; Li, M; Chen, L

    2012-02-01

    In order to generate a better ion beam, a triple-cathode vacuum arc plasma source has been developed. Three plasma generators in the vacuum arc plasma source are equally located on a circle. Each generator initiated by means of a high-voltage breakdown between the cathode and the anode could be operated separately or simultaneously. The arc plasma expands from the cathode spot region in vacuum. In order to study the behaviors of expanding plasma plume generated in the vacuum arc plasma source, a Langmuir probe array is employed to measure the saturated ion current of the vacuum arc plasma source. The time-dependence profiles of the saturated current density of the triple vacuum arc plasma source operated separately and simultaneously are given. Furthermore, the plasma characteristic of this vacuum arc plasma source is also presented in the paper.

  6. An interchangeable-cathode vacuum arc plasma source.

    Science.gov (United States)

    Olson, David K; Peterson, Bryan G; Hart, Grant W

    2010-01-01

    A simplified vacuum arc design [based on metal vapor vacuum arc (MeVVA) concepts] is employed as a plasma source for a study of a (7)Be non-neutral plasma. The design includes a mechanism for interchanging the cathode source. Testing of the plasma source showed that it is capable of producing on the order of 10(12) charges at confinable energies using a boron-carbide disk as the cathode target. The design is simplified from typical designs for lower energy and lower density applications by using only the trigger spark rather than the full vacuum arc in high current ion beam designs. The interchangeability of the cathode design gives the source the ability to replace only the source sample, simplifying use of radioactive materials in the plasma source. The sample can also be replaced with a completely different conductive material. The design can be easily modified for use in other plasma confinement or full MeVVA applications.

  7. Tandem cathode for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Björketun, Mårten E.; Strasser, Peter

    2013-01-01

    tandem cathode design where the full oxygen reduction, involving four electron-transfer steps, is divided into formation (equilibrium potential 0.70 V) followed by reduction (equilibrium potential 1.76 V) of hydrogen peroxide. The two part reactions contain only two electron-transfer steps and one......The efficiency of proton exchange membrane fuel cells is limited mainly by the oxygen reduction reaction at the cathode. The large cathodic overpotential is caused by correlations between binding energies of reaction intermediates in the reduction of oxygen to water. This work introduces a novel...... reaction intermediate each, and they occur on different catalyst surfaces. As a result they can be optimized independently and the fundamental problem associated with the four-electron catalysis is avoided. A combination of density functional theory calculations and published experimental data is used...

  8. Wettable Ceramic-Based Drained Cathode Technology for Aluminum Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    J.N. Bruggeman; T.R. Alcorn; R. Jeltsch; T. Mroz

    2003-01-09

    The goal of the project was to develop the ceramic based materials, technology, and necessary engineering packages to retrofit existing aluminum reduction cells in order to reduce energy consumption required for making primary aluminum. The ceramic materials would be used in a drained cathode configuration which would provide a stable, molten aluminum wetted cathode surface, allowing the reduction of the anode-cathode distance, thereby reducing the energy consumption. This multi-tasked project was divided into three major tasks: (1) Manufacturing and laboratory scale testing/evaluation of the ceramic materials, (2) Pilot scale testing of qualified compositions from the first task, and (3) Designing, retrofitting, and testing the ceramic materials in industrial cells at Kaiser Mead plant in Spokane, Washington. Specific description of these major tasks can be found in Appendix A - Project Scope. Due to the power situation in the northwest, the Mead facility was closed, thus preventing the industrial cell testing.

  9. Electrochemical studies on the cathodic reaction of marine atmospheric corrosion

    Science.gov (United States)

    Wang, Jia

    1996-12-01

    Electrochemical studies on the cathodic reaction of marine atmospheric corrosion using Kelvin probe as reference electrode showed that the rate of cathodic reaction-oxygen reduction first increases then decreases, with the reaction maximizing at a certain thickness as the electrolyte film decreases during evaporation. It was indicated that with decreasing electrolyte thickness by drying, the oxygen reduction rate was accelerated by the faster oxygen diffusion due to the thinner electrolyte layer on the metal surface. The results also revealed that although the oxygen salting out effect has great influence on the rate of oxygen reduction, it is not the main causative factor for the decrease in cathodic limiting current in the case of a very thin electrolyte layer.

  10. Novel nano-network cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Fei [Laboratory for Renewable Clean Energy, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, Anhui (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Wang, Zhiyong; Liu, Mingfei; Zhang, Lei; Xia, Changrong [Laboratory for Renewable Clean Energy, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, Anhui (China); Chen, Fanglin [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2008-10-15

    A novel nano-network of Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} (SSC) is successfully fabricated as the cathodes for intermediate-temperature solid oxide fuel cells (SOFCs) operated at 500-600 C. The cathode is composed of SSC nanowires formed from nanobeads of less than 50 nm thus exhibiting high surface area and porosity, forming straight path for oxygen ion and electron transportation, resulting in high three-phase boundaries, and consequently showing remarkably high electrode performance. An anode-supported cell with the nano-network cathode demonstrates a peak power density of 0.44 W cm{sup -2} at 500 C and displays exceptional performance with cell operating time. The result suggests a new direction to significantly improve the SOFC performance. (author)

  11. Single chamber microbial fuel cell with Ni-Co cathode

    Science.gov (United States)

    Włodarczyk, Barbara; Włodarczyk, Paweł P.; Kalinichenko, Antonina

    2017-10-01

    The possibility of wastewater treatment and the parallel energy production using the Ni-Co alloy as cathode catalyst for single chamber microbial fuel cells is presented in this research. The research included a preparation of catalyst and comparison of COD, NH4+ and NO3- reduction in the reactor without aeration, with aeration and with using a single chamber microbial fuel cell with Ni-Co cathode. The reduction time for COD with the use of microbial fuel cell with the Ni-Co catalyst is similar to the reduction time with aeration. The current density (2.4 A·m-2) and amount of energy (0.48 Wh) obtained in MFC is low, but the obtained amount of energy allows elimination of the energy needed for reactor aeration. It has been shown that the Ni-Co can be used as cathode catalyst in single chamber microbial fuel cells.

  12. Influence of carbon monoxide on the cathode in high-temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Søndergaard, Stine; Cleemann, Lars Nilausen; Jensen, Jens Oluf

    2017-01-01

    This paper describes the results of adding small amounts of CO gas to the cathode side in a HT-PEM fuel cell with a polybenzimidazole (PBI) membrane running on either oxygen or air. Experimental conditions: Temperature ranges 120–160 °C, constant current either 200 mA/cm2 or 800 mA/cm2 and CO...... ranges 0.1–1.3%. In this case it was found that small amounts of CO under special conditions have a beneficial effect on the potential of the fuel cells, whereas larger amounts can bring the potential down to almost zero. An interesting phenomenon is that after the flow of CO is switched off a temporary...

  13. Final Report - Advanced Cathode Catalysts and Supports for PEM Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Debe, Mark

    2012-09-28

    The principal objectives of the program were development of a durable, low cost, high performance cathode electrode (catalyst and support), that is fully integrated into a fuel cell membrane electrode assembly with gas diffusion media, fabricated by high volume capable processes, and is able to meet or exceed the 2015 DOE targets. Work completed in this contract was an extension of the developments under three preceding cooperative agreements/grants Nos. DE-FC-02-97EE50473, DE-FC-99EE50582 and DE-FC36- 02AL67621 which investigated catalyzed membrane electrode assemblies for PEM fuel cells based on a fundamentally new, nanostructured thin film catalyst and support system, and demonstrated the feasibility for high volume manufacturability.

  14. Coupling RTD and EIS modelling to characterize operating non-uniformities on PEM cathodes

    Science.gov (United States)

    Deseure, Jonathan

    Large PEM cells will be used in future proton exchange membrane fuel cell (PEMFC) power plants and appropriate tools are therefore be needed to study their behaviour. One approach to understanding single cell behaviour involves using mathematical models. The numerous techniques used in this work to describe PEM electrode behaviour require different scientific disciplines: chemical engineering and electrochemistry. This study proposes combining residence time distribution (RTD) and electrochemical impedance spectroscopy (EIS). The investigation focuses on cathodic DC and AC responses where over-voltage is critical. Results demonstrate that although gas distribution does not cause additional loops on impedance diagrams, it is strongly related to both the shape and amplitude of these diagrams. The simulations have drawn attention to operating conditions that can threaten the life of the PEM cell: under these setting points EIS method is not sufficient to detect this risk.

  15. Diamond-Like Carbon Film Deposition Using DC Ion Source with Cold Hollow Cathode

    Directory of Open Access Journals (Sweden)

    E. F. Shevchenko

    2014-01-01

    Full Text Available Carbon diamond-like thin films on a silicon substrate were deposited by direct reactive ion beam method with an ion source based on Penning direct-current discharge system with cold hollow cathode. Deposition was performed under various conditions. The pressure (12–200 mPa and the plasma-forming gas composition consisting of different organic compounds and hydrogen (C3H8, CH4, Si(CH32Cl2, H2, the voltage of accelerating gap in the range 0.5–5 kV, and the substrate temperature in the range 20–850°C were varied. Synthesized films were researched using nanoindentation, Raman, and FTIR spectroscopy methods. Analysis of the experimental results was made in accordance with a developed model describing processes of growth of the amorphous and crystalline carbon materials.

  16. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Directory of Open Access Journals (Sweden)

    Mahmoud Bakr

    2011-06-01

    Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  17. Electrochemical performance and degradation of (La0.6Sr0.4)0.99CoO3 − δ as porous SOFC-cathode

    DEFF Research Database (Denmark)

    Hjalmarsson, Per; Mogensen, Mogens Bjerg; Søgaard, Martin

    2008-01-01

    This paper shows that measured impedance in porous (La0.6Sr0.4)(0.99)CoO3-delta cathodes can be dependent on both gas diffusion and electrode kinetics at temperatures above 700 degrees C or below ambient pO(2)S if electrode kinetics are fast. The reaction mechanism is discussed on the basis...

  18. Study on cathode high voltage pulse control in image intensifier

    Science.gov (United States)

    Yang, Ye; Yan, Bo; Ni, Xiao-bing; Zhi, Qiang; Li, Jun-guo; Yao, Ze; Deng, Guang-xu

    2016-03-01

    This paper briefly introduces the basic working principle of auto-gating power source. Due to the presence of noise in the circuit, the cathode pulse signal generated by the AD converter is unstable. In this paper, the circuit of the AD converter is adjusted to improve the instability of the cathode high voltage pulse signal, especially in the case of low light and high illumination to avoid the jitter of the pulse. The experiment was carried out. And it could guide the implementation of this part of the circuit.

  19. Tolerant chalcogenide cathodes of membraneless micro fuel cells.

    Science.gov (United States)

    Gago, Aldo Saul; Gochi-Ponce, Yadira; Feng, Yong-Jun; Esquivel, Juan Pablo; Sabaté, Neus; Santander, Joaquin; Alonso-Vante, Nicolas

    2012-08-01

    The most critical issues to overcome in micro direct methanol fuel cells (μDMFCs) are the lack of tolerance of the platinum cathode and fuel crossover through the polymer membrane. Thus, two novel tolerant cathodes of a membraneless microlaminar-flow fuel cell (μLFFC), Pt(x)S(y) and CoSe(2), were developed. The multichannel structure of the system was microfabricated in SU-8 polymer. A commercial platinum cathode served for comparison. When using 5 M CH(3)OH as the fuel, maximum power densities of 6.5, 4, and 0.23 mW cm(-2) were achieved for the μLFFC with Pt, Pt(x)S(y), and CoSe(2) cathodes, respectively. The Pt(x)S(y) cathode outperformed Pt in the same fuel cell when using CH(3)OH at concentrations above 10 M. In a situation where fuel crossover is 100 %, that is, mixing the fuel with the reactant, the maximum power density of the micro fuel cell with Pt decreased by 80 %. However, for Pt(x)S(y) this decrease corresponded to 35 % and for CoSe(2) there was no change in performance. This result is the consequence of the high tolerance of the chalcogenide-based cathodes. When using 10 M HCOOH and a palladium-based anode, the μLFFC with a CoSe(2) cathode achieved a maxiumum power density of 1.04 mW cm(-2). This micro fuel cell does not contain either Nafion membrane or platinum. We report, for the first time, the evaluation of Pt(x)S(y)- and CoSe(2)-based cathodes in membraneless micro fuel cells. The results suggest the development of a novel system that is not size restricted and its operation is mainly based on the selectivity of its electrodes. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Oxide cathode lifetime improvements at RTNS-II

    Energy Technology Data Exchange (ETDEWEB)

    Massoletti, D.J.

    1986-09-29

    Results are reported for an ongoing effort to optimize D/sup +/ beam production by the MATS-III ion source used at the RTNS-II. The oxide cathode assembly originally designed for lower power operation has been modified and redesigned for higher electron current yield, longer life and serviceability. A factor of 2.5 has been gained in cathode lifetime due to these changes. The details of the changes and results and benefits in operation and performance are given. In addition, the technique used for manufacture of the filament is described.

  1. Field-emission cathode gating for rf electron guns

    OpenAIRE

    Lewellen, J. W.; J. Noonan

    2005-01-01

    We present a novel method of combining the most desirable characteristics of thermionic-cathode and photocathode rf guns, using a field-emission cathode and multiple rf frequencies. Simulations indicate that extremely low-emittance beams (on the order of 2 nm normalized emittance) at moderate beam currents (1 mA) and beam energies of ∼2  MeV can be obtained using this technique. The resulting gun design promises to be useful as a driver source for a number of applications, including high-volt...

  2. Platform cathodic protection design in the South China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Rippon, I. [Sarawak Shell Berhad (Malaysia)

    1997-09-01

    The 1993 revision of one of the industry recommended practices on cathodic protection design offers the operator the opportunity to use his own experience and data to justify more or less conservative designs. Examples of the use of this option to achieve an economic South China Sea design are presented. The design approach on how to subdivide the object being cathodically protected can be applied in any operating area where there is good environmental data. An example of the cost savings achievable by using this approach is presented. The optimized design is 55% of the cost of the design following the 1993 code.

  3. Effort towards symmetric removal and surface smoothening of 1.3-GHz niobium single-cell cavity in vertical electropolishing using a unique cathode

    Science.gov (United States)

    Chouhan, Vijay; Kato, Shigeki; Nii, Keisuke; Yamaguchi, Takanori; Sawabe, Motoaki; Hayano, Hitoshi; Ida, Yoshiaki

    2017-08-01

    A detailed study on vertical electropolishing (VEP) of a 1.3-GHz single-cell niobium coupon cavity, which contains six coupons and four viewports at different positions, is reported. The cavity was vertically electropolished using a conventional rod and three types of unique cathodes named as Ninja cathodes, which were designed to have four retractable blades made of either an insulator or a metal or a combination of both. This study reveals the effect of the cathodes and their rotation speed on uniformity in removal thickness and surface morphology at different positions inside the cavity. Removal thickness was measured at several positions of the cavity using an ultrasonic thickness gauge and the surface features of the coupons were examined by an optical microscope and a surface profiler. The Ninja cathode with partial metallic blades was found to be effective not only in reducing asymmetric removal, which is one of the major problems in VEP and might be caused by the accumulation of hydrogen (H2 ) gas bubbles on the top iris of the cavity, but also in yielding a smooth surface of the entire cavity. A higher rotation speed of the Ninja cathode prevents bubble accumulation on the upper iris, and might result in a viscous layer of similar thickness in the cavity cell. Moreover, a higher electric field at the equator owing to the proximity of partial metallic blades to the equator surface resulted in a smooth surface. The effects of H2 gas bubbles and stirring were also observed in lab EP experiments.

  4. Effort towards symmetric removal and surface smoothening of 1.3-GHz niobium single-cell cavity in vertical electropolishing using a unique cathode

    Directory of Open Access Journals (Sweden)

    Vijay Chouhan

    2017-08-01

    Full Text Available A detailed study on vertical electropolishing (VEP of a 1.3-GHz single-cell niobium coupon cavity, which contains six coupons and four viewports at different positions, is reported. The cavity was vertically electropolished using a conventional rod and three types of unique cathodes named as Ninja cathodes, which were designed to have four retractable blades made of either an insulator or a metal or a combination of both. This study reveals the effect of the cathodes and their rotation speed on uniformity in removal thickness and surface morphology at different positions inside the cavity. Removal thickness was measured at several positions of the cavity using an ultrasonic thickness gauge and the surface features of the coupons were examined by an optical microscope and a surface profiler. The Ninja cathode with partial metallic blades was found to be effective not only in reducing asymmetric removal, which is one of the major problems in VEP and might be caused by the accumulation of hydrogen (H_{2} gas bubbles on the top iris of the cavity, but also in yielding a smooth surface of the entire cavity. A higher rotation speed of the Ninja cathode prevents bubble accumulation on the upper iris, and might result in a viscous layer of similar thickness in the cavity cell. Moreover, a higher electric field at the equator owing to the proximity of partial metallic blades to the equator surface resulted in a smooth surface. The effects of H_{2} gas bubbles and stirring were also observed in lab EP experiments.

  5. Current-voltage characteristics of a cathodic plasma contactor with discharge chamber for application in electrodynamic tether propulsion

    Science.gov (United States)

    Xie, Kan; Martinez, Rafael A.; Williams, John D.

    2014-04-01

    This paper focuses on the net electron-emission current as a function of bias voltage of a plasma source that is being used as the cathodic element in a bare electrodynamic tether system. An analysis is made that enables an understanding of the basic issues determining the current-voltage (C-V) behaviour. This is important for the efficiency of the electrodynamic tether and for low impedance performance without relying on the properties of space plasma for varying orbital altitudes, inclinations, day-night cycles or the position of the plasma contactor relative to the wake of the spacecraft. The cathodic plasma contactor considered has a cylindrical discharge chamber (10 cm in diameter and ˜11 cm in length) and is driven by a hollow cathode. Experiments and a 1D spherical model are both used to study the contactor's C-V curves. The experiments demonstrate how the cathodic contactor would emit electrons into space for anode voltages in the range of 25-40 V, discharge currents in the range of 1-2.5 A, and low xenon gas flows of 2-4 sccm. Plasma properties are measured and compared with (3 A) and without net electron emission. A study of the dependence of relevant parameters found that the C-V behaviour strongly depends on electron temperature, initial ion energy and ion emission current at the contactor exit. However, it depended only weakly on ambient plasma density. The error in the developed model compared with the experimental C-V curves is within 5% at low electron-emission currents (0-2 A). The external ionization processes and high ion production rate caused by the discharge chamber, which dominate the C-V behaviour at electron-emission currents over 2 A, are further highlighted and discussed.

  6. Unusual kinetic behavior in cathodic H2 evolution from KF.2HF melts at mild-steel and alloy electrodes

    Directory of Open Access Journals (Sweden)

    Conway Con B.E.

    2004-01-01

    Full Text Available Apart from its interest as a "model" process for kinetic studies of gas-evolving electrode reactions, the cathodic hydrogen evolution reaction (her is involved in several processes that are of importance in applied electrochemistry, e.g., as the cathodic co-reactions in the commercial production of C12 and F2, in electrolyses for production of hydrogen, in electrochemical hydrogenation and, indirectly, as the partial process in corrosion of base metals in the absence of oxygen. The present paper reports several aspects of the unusual behavior of the her that is involved as the co-reaction to electrolytic production of F2 from KF/HF melts using carbon anodes and Fe or mild-steel cathodes. Anomalous anodic polarization behavior that arises in electrolytic generation of F2 from KF/HF melts at carbon electrodes is well known. It is characterized by very high Tafel slopes associated with "CF" film formation and by sluggish F2 bubble disengagement from the electrode. Interest in such effects has, however, tended to overshadow rather similar, so-called "hyper polarization" effects that also arise in the cathodic reaction, but for different reasons. The origins and nature of such effects are described and characterized in the present paper, and comparisons are made between behavior of Hz evolution from KF.2HF and that from the aquo-system analogue, KOH.2H2O. An important aspect is the very different interfacial behavior in KF/HF or KF.2HF melts from that in the corresponding aquo-system. Effects of As-species in HF feeds is investigated in terms of electro catalysis and poisoning effects on the her.

  7. Investigation of spinel-related and orthorhombic LiMNO2 cathodes for rechargeable lithium batteries

    CSIR Research Space (South Africa)

    Gummow, RJ

    1994-05-01

    Full Text Available Cathode materials that have been synthesized by reduction of lithium-manganese- Cathode materials that have been synthesized by reduction of lithium-manganese-oxide and manganese-oxide precursors with hydrogen at 300 to 350-degrees...

  8. Power generation using an activated carbon and metal mesh cathode in a microbial fuel cell

    KAUST Repository

    Zhang, Fang

    2009-11-01

    An inexpensive activated carbon (AC) air cathode was developed as an alternative to a platinum-catalyzed electrode for oxygen reduction in a microbial fuel cell (MFC). AC was cold-pressed with a polytetrafluoroethylene (PTFE) binder to form the cathode around a Ni mesh current collector. This cathode construction avoided the need for carbon cloth or a metal catalyst, and produced a cathode with high activity for oxygen reduction at typical MFC current densities. Tests with the AC cathode produced a maximum power density of 1220 mW/m2 (normalized to cathode projected surface area; 36 W/m3 based on liquid volume) compared to 1060 mW/m2 obtained by Pt catalyzed carbon cloth cathode. The Coulombic efficiency ranged from 15% to 55%. These findings show that AC is a cost-effective material for achieving useful rates of oxygen reduction in air cathode MFCs. © 2009 Elsevier B.V. All rights reserved.

  9. Continuing life test of a xenon hollow cathode for a space plasma contactor

    Science.gov (United States)

    Sarver-Verhey, Timothy R.

    1994-01-01

    Implementation of a hollow cathode plasma contactor for charge control on the Space Station has required validation of long-life hollow cathodes. A test series of hollow cathodes and hollow cathode plasma contactors was initiated as part of the plasma contactor development program. An on-going wear-test of a hollow cathode has demonstrated cathode operation in excess of 10,000 hours with small changes in operating parameters. The discharge has experienced 10 shutdowns during the test, all of which were due to test facility failures or expellant replenishment. In all cases, the cathode was re-ignited at approximately 42 volts and resumed typical operation. This test represents the longest demonstrated stable operation of a high current (greater than 1 A) xenon hollow cathode reported to date.

  10. Extended test of a xenon hollow cathode for a space plasma contactor

    Science.gov (United States)

    Sarver-Verhey, Timothy R.

    1994-01-01

    Implementation of a hollow cathode plasma contactor for charge control on the Space Station has required validation of long-life hollow cathodes. A test series of hollow cathodes and hollow cathode plasma contactors was initiated as part of the plasma contactor development program. An on-going wear-test of a hollow cathode has demonstrated cathode operation in excess of 4700 hours with small changes in operating parameters. The discharge experienced 4 shutdowns during the test, all of which were due to test facility failures or expellant replenishment. In all cases, the cathode was reignited at approximately 42 volts and resumed typical operation. This test represents the longest demonstrated stable operation of a high current (greater than 1A) xenon hollow cathode reported to date.

  11. Nano-Particle Scandate Cathode for Space Communications Phase 2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an improved cathode based on our novel theory of the role of scandium oxide in enhancing emission in tungsten-impregnated cathodes. Recent results have...

  12. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Science.gov (United States)

    2010-10-01

    ... I. Criteria for cathodic protection— A. Steel, cast iron, and ductile iron structures. (1) A... cathodic protection to stop pitting attack on aluminum structures in environments with a natural pH in...

  13. Research and Development of a New Field Enhanced Low Temperature Thermionic Cathode that Enables Fluorescent Dimming and Loan Shedding without Auxiliary Cathode Heating

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jin

    2009-01-07

    This is the final report for project entitled 'Research and development of a new field enhanced low temperature thermionic cathode that enables fluorescent dimming and load shedding without auxiliary cathode heating', under Agreement Number: DE-FC26-04NT-42329. Under this project, a highly efficient CNT based thermionic cathode was demonstrated. This cathode is capable of emitting electron at a current density two order of magnitude stronger then a typical fluorescent cathode at same temperatures, or capable of emitting at same current density but at temperature about 300 C lower than that of a fluorescent cathode. Detailed fabrication techniques were developed including CVD growth of CNTs and sputter deposition of oxide thin films on CNTs. These are mature technologies that have been widely used in industry for large scale materials processing and device fabrications, thus, with further development work, the techniques developed in this project can be scaled-up in manufacturing environment. The prototype cathodes developed in this project were tested in lighting plasma discharge environment. In many cases, they not only lit and sustain the plasma, but also out perform the fluorescent cathodes in key parameters such like cathode fall voltages. More work will be needed to further evaluate more detailed and longer term performance of the prototype cathode in lighting plasma.

  14. Testing a GaAs cathode in SRF gun

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.; Kewisch, J.; Ben-Zvi, I.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2011-03-28

    RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10{sup -12} Torr because of cryo-pumping at 2K. With conventional activation of bulk GaAs, we obtained a QE of 10% at 532 nm, with lifetime of more than 3 days in the preparation chamber and have shown that it can survive in transport from the preparation chamber to the gun. The beam line has been assembled and we are exploring the best conditions for baking the cathode under vacuum. We report here the progress of our test of the GaAs cathode in the SRF gun. Future particle accelerators, such as eRHIC and the ILC require high-brightness, high-current polarized electrons. Strained superlattice GaAs:Cs has been shown to be an efficient cathode for producing polarized electrons. Activation of GaAs with Cs,O(F) lowers the electron affinity and makes it energetically possible for all the electrons, excited into the conduction band that drift or diffuse to the emission surface, to escape into the vacuum. Presently, all operating polarized electron sources, such as the CEBAF, are DC guns. In these devices, the excellent ultra-high vacuum extends the lifetime of the cathode. However, the low field gradient on the photocathode's emission surface of the DC guns limits the beam quality. The higher accelerating gradients, possible in the RF guns, generate a far better beam. Until recently, most RF guns operated at room temperature, limiting the vacuum to {approx}10{sup -9} Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and

  15. Theory, Investigation and Stability of Cathode Electrocatalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Dong; Liu, Mingfei; Lai, Samson; Blinn, Kevin; Liu, Meilin

    2012-09-30

    The main objective of this project is to systematically characterize the surface composition, morphology, and electro-catalytic properties of catalysts coated on LSCF, aiming to establish the scientific basis for rational design of high-performance cathodes by combining a porous backbone (such as LSCF) with a thin catalyst coating. The understanding gained will help us to optimize the composition and morphology of the catalyst layer and microstructure of the LSCF backbone for better performance. More specifically, the technical objectives include: (1) to characterize the surface composition, morphology, and electro-catalytic properties of catalysts coated on LSCF; (2) to characterize the microscopic details and stability of the LSCF-catalyst (e.g., LSM) interfaces; (3) to establish the scientific basis for rational design of high-performance cathodes by combining a porous backbone (such as LSCF) with a thin catalyst coating; and (4) to demonstrate that the performance and stability of porous LSCF cathodes can be enhanced by the application of a thin-film coating of LSM through a solution infiltration process in small homemade button cells and in commercially available cells of larger dimension. We have successfully developed dense, conformal LSM films with desired structure, composition, morphology, and thickness on the LSCF surfaces by two different infiltration processes: a non-aqueous and a water-based sol-gel process. It is demonstrated that the activity and stability of LSCF cathodes can be improved by the introduction of a thin-film LSM coating through an infiltration process. Surface and interface of the LSM-coated LSCF cathode were systematically characterized using advanced microscopy and spectroscopy techniques. TEM observation suggests that a layer of La and Sr oxide was formed on LSCF surfaces after annealing. With LSM infiltration, in contrast, we no longer observe such La/Sr oxide layer on the LSM-coated LSCF samples after annealing under similar

  16. Nano-structured textiles as high-performance aqueous cathodes for microbial fuel cells

    KAUST Repository

    Xie, Xing

    2011-01-01

    A carbon nanotube (CNT)-textile-Pt cathode for aqueous-cathode microbial fuel cells (MFCs) was prepared by electrochemically depositing Pt nanoparticles on a CNT-textile. An MFC equipped with a CNT-textile-Pt cathode revealed a 2.14-fold maximum power density with only 19.3% Pt loading, compared to that with a commercial Pt coated carbon cloth cathode. © 2011 The Royal Society of Chemistry.

  17. Application of hyperdispersant to the cathode diffusion layer for direct methanol fuel cell

    Science.gov (United States)

    Mao, Qing; Sun, Gongquan; Wang, Suli; Sun, Hai; Tian, Yang; Tian, Juan; Xin, Qin

    In this study, Nafion ionomer, as a kind of hyperdispersant, was added to polytetrafluoroethylene (PTFE) water dispersion system to suppress the size of PTFE particles in the ink of microporous layer (MPL). The agglomeration behavior of PTFE in ethanol and MPL were investigated by laser diffraction, dynamic light scattering (DLS) and metallurgical microscopes. The electronic resistance, pore size distribution, gas permeability and surface hydrophobic/hydrophilic properties were also characterized for prepared gas diffusion layers (GDLs). It was shown that PTFE water dispersion system suffered flocculating when dispersed in ethanol and this agglomeration behavior was reduced by employing Nafion ionomer. With the increase in the Nafion ionomer adopted in the MPL, not only the decreased hydrophobic property was shown in the MPL, but the decreased PTFE particle size was also achieved, which results in improved crosslink of carbon and pores themselves as well as the volume loss of pores in micron scale. The increased gas permeability and electronic conductivity of the GDL made the one employing the PTFE dispersion system with 1% Nafion content own its advantages as the cathode diffusion layer for a direct methanol fuel cell (DMFC) under near-ambient conditions.

  18. Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

    Science.gov (United States)

    Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

  19. Performance testing of a carbon fiber array cathode in a hard-tube MILO

    Science.gov (United States)

    Li, An-Kun; Fan, Yu-Wei; Qian, Bao-Liang

    2017-10-01

    In this paper, a carbon fiber array cathode was constructed and the application in a hard-tube magnetically insulated transmission line oscillator (MILO) was investigated. The performance was compared with a traditionally used polymer velvet cathode in the same conditions, where applied electric power ranged from 9 GW to 28 GW and microwave with power level of several GW was the output. The MILO worked on single shot mode or repetitive mode at 5 Hz. For both cathodes, the central frequencies of output microwaves are in the L-band, and the pulse durations (full width at half maximum) range from 25 to 50 ns. Experimental results show that the pulse duration of output microwave of the carbon fiber array cathode is shorter than the velvet cathode, and the power conversion efficiency is also somewhat lower than the velvet cathode. Although the performance testing results show that this carbon fiber array cathode is somewhat not as good as the traditional velvet cathode in the present state, the reasons for the disadvantages of the carbon fiber array cathode have been analyzed and the corresponding solutions are presented to improve the performance of this cathode. If expected solutions are put into effect, this carbon fiber array cathode may be able to replace the velvet cathode.

  20. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical cathode-ray tube display. 870.2450 Section... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device designed primarily to display selected biological signals. This device often incorporates special display features...

  1. High performance and durability of order-structured cathode catalyst layer based on TiO{sub 2}@PANI core-shell nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ming; Wang, Meng; Yang, Zhaoyi [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); Wang, Xindong, E-mail: echem@ustb.edu.cn [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 30 College Road, Beijing 100083 (China)

    2017-06-01

    Highlights: • TiO{sub 2}@PANI core-shell nanowire arrays were prepared and applied as catalyst support. • As-prepared Pt-TiO{sub 2}@PANI core-shell nanowire arrays were applied as order-structured cathode catalyst layer. • The novel cathode catalyst structure without Nafion{sup ®} ionomer enhance the performance and durability of PEMFC. - Abstract: In this paper, an order-structured cathode catalyst layer consisting of Pt-TiO{sub 2}@PANI core-shell nanowire arrays that in situ grown on commercial gas diffusion layer (GDL) are prepared and applied to membrane electrode assembly (MEA) of proton exchange membrane fuel cell (PEMFC). In order to prepare the TiO{sub 2}@PANI core-shell nanowire arrays with suitable porosity and prominent conductivity, the morphologies of the TiO{sub 2} nanoarray and electrochemical polymerization process of aniline are schematically investigated. The MEA with order-structured cathode catalyst layer is assembled in the single cell to evaluate the electrochemical performance and durability of PEMFC. As a result, the PEMFC with order-structured cathode catalyst layer shows higher peak power density (773.54 mW cm{sup −2}) than conventional PEMFC (699.30 mW cm{sup −2}). Electrochemically active surface area (ECSA) and charge transfer impedance (R{sub ct}) are measured before and after accelerated degradation test (ADT), and the corresponding experimental results indicate the novel cathode structure exhibits a better stability with respect to conventional cathode. The enhanced electrochemical performance and durability toward PEMFC can be ascribed to the order-structured cathode nanoarray structure with high specific surface area increases the utilization of catalyst and reduces the tortuosity of transport pathways, and the synergistic effect between TiO{sub 2}@PANI support and Pt nanoparticles promotes the high efficiency of electrochemical reaction and improves the stability of catalyst. This research provides a facile and

  2. Effect of process parameters on coating composition of cathodic ...

    Indian Academy of Sciences (India)

    The effect of some process parameters such as electrical conductivity, volume and temperature of electrolyte and ratio of anode to cathode surface area on current–voltage behaviour and subsequently coating compositions are investigated at 150V deposition voltage. The composition and morphology of these coatings are ...

  3. Degradation Studies on LiFePO4 cathode

    DEFF Research Database (Denmark)

    Scipioni, Roberto; Jørgensen, Peter Stanley; Hjelm, Johan

    2015-01-01

    In this paper we examine a laboratory LiFePO4 (LFP) cathode and propose a simple model that predicts the electrode capacity as function of C-rate, number of cycles and calendar time. Microcracks were found in Li1-xFePO4 particles in a degraded LFP electrode and low-acceleration voltage (1 kV) FIB...

  4. FEM-models of cathodic protection systems for concrete structures

    NARCIS (Netherlands)

    Bertolini, L.; Lollini, F.; Redaelli, E.; Polder, R.B.; Peelen, W.H.A.

    2008-01-01

    A significant number of reinforced concrete structures shows deterioration due to the reinforcement corrosion and requires interventions to guarantee their residual service life. A wide range of maintenance options is available, among which cathodic protection (CP) has been found to be a successful

  5. Influence of substrate topography on cathodic delamination of anticorrosive coatings

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Kiil, Søren; Dam-Johansen, Kim

    2009-01-01

    The cathodic delamination of a commercial magnesium silicate and titanium dioxide pigmented epoxy coating on abrasive cleaned cold rolled steel has been investigated. The rate of delamination was found to depend on interfacial transport from the artificial defect to the delamination front...

  6. Cathodic protection of RC structures - Far more than bridge decks

    NARCIS (Netherlands)

    Nerland, O.C.; Polder, R.B.

    2002-01-01

    When the first trials with Cathodic Protection (CP) on reinforced concrete (RC) structures were carried out nearly 30 years ago the main aim was treating steel in bridge decks, suffering from chloride induced corrosion. Various types of anode systems (conductive asphalt, conductive mortars, carbon

  7. Enhancement of Platinum Cathode Catalysis by Addition of Transition Metals

    Science.gov (United States)

    Duong, Hung Tuan

    2009-01-01

    The sluggish kinetics of oxygen reduction reaction (ORR) contributes significantly to the loss of cathode overpotential in fuel cells, thus requiring high loadings of platinum (Pt), which is an expensive metal with limited supply. However, Pt and Pt-based alloys are still the best available electrocatalysts for ORR thus far. The research presented…

  8. Interactions of alkali metals and electrolyte with cathode carbons

    Energy Technology Data Exchange (ETDEWEB)

    Naas, Tyke

    1997-12-31

    The Hall-Heroult process for electrolytic reduction of alumina has been the only commercial process for production of primary aluminium. The process runs at high temperature and it is important to minimize the energy consumption. To save energy it is desirable to reduce the operating temperature. This can be achieved by adding suitable additives such as LiF or KF to the cryolitic electrolyte. This may conflict with the objective of extending the lifetime of the cathode linings of the cell as much as possible. The thesis investigates this possibility and the nature of the interactions involved. It supports the hypothesis that LiF-additions to the Hall-Heroult cell electrolyte is beneficial to the carbon cathode performance because the diminished sodium activity reduces the sodium induced stresses during the initial period of electrolysis. The use of KF as an additive is more dangerous, but the results indicate that additions up to 5% KF may be tolerated in acidic melts with semigraphitic or graphitic cathodes with little risk of cathode problems. 153 refs., 94 figs., 30 tabs.

  9. Cathodic Arcs From Fractal Spots to Energetic Condensation

    CERN Document Server

    Anders, Andre

    2009-01-01

    Emphasizes the fractal character of cathode spots, and describes strongly fluctuating plasma properties such as the presence of multiply charged ions that move with supersonic velocity. This book also deals with issues, such as arc source construction, and macroparticle removal. It is intended for scientists, practitioners, and students alike

  10. Advanced numerical design for economical cathodic protection for concrete structures

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.

    2008-01-01

    Concrete structures under aggressive load may suffer chloride induced reinforcement corrosion, in particular with increasing age. Due to high monetary and societal cost (non-availability), replacement is often undesirable. Durable repair is necessary, e.g. by Cathodic Protection (CP). CP involves an

  11. Impregnation of LSM Based Cathodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Højberg, Jonathan; Søgaard, Martin

    2011-01-01

    Composites cathodes consisting of strontium doped lanthanum manganite (LSM) and yttria stabilized zirconia have been impregnated with the nitrates corresponding to the nominal compositions: La0.75Sr0.25Mn1.05O3 +/-delta (LSM25), Ce0.8Sm0.2O2 (SDC) and a combination of both (dual). The latter...

  12. Long-Term Stability of LSM-YSZ Based Cathodes

    DEFF Research Database (Denmark)

    Baqué, Laura; Jørgensen, Peter Stanley; Hansen, Karin Vels

    2013-01-01

    A transmission line based model was successfully applied to study the ageing effect in LSM-YSZ cathodes after being exposed to humidified air at 900 °C for up to 3000 h. A decrease in the YSZ conductivity was correlated with the formation of the less conducting monoclinic zirconia. The amount of La...

  13. Engineering analyses of large precision cathode strip chambers for GEM

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, J.A.; Belser, F.C.; Pratuch, S.M.; Wuest, C.R. [Lawrence Livermore National Lab., CA (United States); Mitselmakher, G. [Superconducting Super Collider Lab., Dallas, TX (United States); Gordeev, A. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Johnson, C.V. [Lawrence Livermore National Lab., CA (United States)]|[Superconducting Super Collider Lab., Dallas, TX (United States); Polychronakos, V.A. [Brookhaven National Lab., Upton, NY (United States); Golutvin, I.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    1993-10-21

    Structural analyses of large precision cathode strip chambers performed up to the date of this publication are documented. Mechanical property data for typical chamber materials are included. This information, originally intended to be an appendix to the {open_quotes}CSC Structural Design Bible,{close_quotes} is presented as a guide for future designers of large chambers.

  14. High Performance Infiltrated Backbones for Cathode-Supported SOFC's

    DEFF Research Database (Denmark)

    Gil, Vanesa; Kammer Hansen, Kent

    2014-01-01

    The concept of using highly ionic conducting backbones with subsequent infiltration of electronically conducting particles has widely been used to develop alternative anode-supported SOFC's. In this work, the idea was to develop infiltrated backbones as an alternative design based on cathode...

  15. Composite Cathodes for Dual-Rate Li-Ion Batteries

    Science.gov (United States)

    Whitacre, Jay; West, William; Bugga, Ratnakumar

    2008-01-01

    Composite-material cathodes that enable Li-ion electrochemical cells and batteries to function at both high energy densities and high discharge rates are undergoing development. Until now, using commercially available cathode materials, it has been possible to construct cells that have either capability for high-rate discharge or capability to store energy at average or high density, but not both capabilities. However, both capabilities are needed in robotic, standby-power, and other applications that involve duty cycles that include long-duration, low-power portions and short-duration, high-power portions. The electrochemically active ingredients of the present developmental composite cathode materials are: carbon-coated LiFePO4, which has a specific charge capacity of about 160 mA h/g and has been used as a high-discharge-rate cathode material and Li[Li(0.17)Mn(0.58)Ni(0.25)]O2, which has a specific charge capacity of about 240 mA h/g and has been used as a high-energy-density cathode material. In preparation for fabricating the composite material cathode described, these electrochemically active ingredients are incorporated into two sub-composites: a mixture comprising 10 weight percent of poly(vinylidine fluoride); 10 weight percent of carbon and 80 weight percent of carbon coated LiFePO4; and, a mixture comprising 10 weight percent of PVDF, and 80 weight percent of Li[Li(0.17)Mn(0.58)Ni(0.25)]O2. In the fabrication process, these mixtures are spray-deposited onto an aluminum current collector. Electrochemical tests performed thus far have shown that better charge/discharge performance is obtained when either 1) each mixture is sprayed on a separate area of the current collector or (2) the mixtures are deposited sequentially (in contradistinction to simultaneously) on the same current-collector area so that the resulting composite cathode material consists of two different sub-composite layers.

  16. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  17. A Study of the Influence of Gas Channel Parameters on HT-PEM Fuel Cell Performance Using FEM Analysis

    Directory of Open Access Journals (Sweden)

    Ionescu Viorel

    2016-01-01

    Full Text Available Proton Exchange Membrane Fuel Cells (PEMFC are highly efficient power generators, achieving up to 50–60% conversion efficiency, even in sizes of a few kilowatts. Comsol Multiphysics, a commercial solver based on the Finite Element Method (FEM was used for developing a three dimensional model of a high temperature PEMFC that can deal with both anode and cathode flow field for examining the micro flow channel with electrochemical reaction. Cathode gas flow velocity influence on the cell performance was investigated at first. Polarization curves for three different channel widths (0.8, 1.6 and 2.4 mm and three different channel depths (1, 2 and 3 mm were computed at a cathode inlet flow velocity of 0.06 m/s. Oxygen molar concentration at cathode catalyst layer-GDL channel interface and local current density variation along the cell length were also studied for specific gas channel geometries.

  18. Functionally Graded Cathodes for Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Harry Abernathy; Meilin Liu

    2006-12-31

    One primary suspected cause of long-term performance degradation of solid oxide fuels (SOFCs) is the accumulation of chromium (Cr) species at or near the cathode/electrolyte interface due to reactive Cr molecules originating from Cr-containing components (such as the interconnect) in fuel cell stacks. To date, considerable efforts have been devoted to the characterization of cathodes exposed to Cr sources; however, little progress has been made because a detailed understanding of the chemistry and electrochemistry relevant to the Cr-poisoning processes is still lacking. This project applied multiple characterization methods - including various Raman spectroscopic techniques and various electrochemical performance measurement techniques - to elucidate and quantify the effect of Cr-related electrochemical degradation at the cathode/electrolyte interface. Using Raman microspectroscopy the identity and location of Cr contaminants (SrCrO{sub 4}, (Mn/Cr){sub 3}O{sub 4} spinel) have been observed in situ on an LSM cathode. These Cr contaminants were shown to form chemically (in the absence of current flowing through the cell) at temperatures as low as 625 C. While SrCrO{sub 4} and (Mn/Cr){sub 3}O{sub 4} spinel must preferentially form on LSM, since the LSM supplies the Sr and Mn cations necessary for these compounds, LSM was also shown to be an active site for the deposition of Ag{sub 2}CrO{sub 4} for samples that also contained silver. In contrast, Pt and YSZ do not appear to be active for formation of Cr-containing phases. The work presented here supports the theory that Cr contamination is predominantly chemically-driven and that in order to minimize the effect, cathode materials should be chosen that are free of cations/elements that could preferentially react with chromium, including silver, strontium, and manganese.

  19. Synchrotron X-ray studies of model SOFC cathodes, part II: Porous powder cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kee-Chul; Ingram, Brian; Ilavsky, Jan; Lee, Shiwoo; Fuoss, Paul; You, Hoydoo

    2017-11-01

    Infiltrated La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) sintered porous powder cathodes for solid oxide fuel cells have been investigated by synchrotron ultra-small angle x-ray scattering (USAXS). We demonstrated that atomic layer deposition (ALD) is the method for a uniform coating and liquid-phase infiltration for growing nanoscale particles on the porous LSCF surfaces. The MnO infiltrate, grown by ALD, forms a conformal layer with a uniform thickness throughout the pores evidenced by USAXS thickness fringes. The La0.6Sr0.4CoO3 (LSC) and La2Zr2O7 (LZO) infiltrates, grown by liquid-phase infiltration, were found to form nanoscale particles on the surfaces of LSCF particles resulting in increased surface areas. Impedance measurements suggest that the catalytic property of LSC infiltrate, not the increased surface area of LZO, is important for increasing oxygen reduction activities.

  20. Static and dynamic modelling of gas turbines in advanced cycles

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Jan-Olof

    1998-12-01

    Gas turbines have been in operation for at least 50 years. The engine is used for propulsion of aircraft and high speed ships. It is used for power production in remote locations and for peak load and emergency situations. Gas turbines have been used in combined cycles for 20 to 30 years. Highly efficient power plants based on gas turbines are a competitive option for the power industry today. The thermal efficiency of the simple cycle gas turbine has increased due to higher turbine inlet temperatures and improved compressor and expander designs. Equally important are the improved cycles in which the gas turbine operates. One example is the combined cycle that uses steam for turbine cooling. Steam is extracted from the bottoming cycle, then used as airfoil coolant in a closed loop and returned to the bottoming cycle. The Evaporative Gas Turbine (EvGT), also known as the Humid Air Turbine (HAT), is another advanced cycle. A mixture of air and water vapour is used as working media. Air from the compressor outlet is humidified and then preheated in a recuperator prior to combustion. The static and dynamic performance is changed when the gas turbine is introduced in an evaporative cycle. The cycle is gaining in popularity, but so far it has not been demonstrated. A Swedish joint program to develop the cycle has been in operation since 1993. As part of the program, a small pilot plant is being erected at the Lund Institute of Technology (LTH). The plant is based on a 600 kW gas turbine, and demonstration of the EvGT cycle started autumn 1998 and will continue, in the present phase, for one year. This thesis presents static and dynamic models for traditional gas turbine components, such as, the compressor, combustor, expander and recuperator. A static model for the humidifier is presented, based on common knowledge for atmospheric humidification. All models were developed for the pilot plant at LTH with the objective to support evaluation of the process and individual

  1. Cathodic protection of reinforced concrete structures in the Netherlands - Experience and developments: Cathodic protection of concrete - 10 years experience

    NARCIS (Netherlands)

    Polder, R.B.

    1998-01-01

    Cathodic protection (CP) of reinforcing steel in concrete structures has been used successfully for over 20 years. CP is able to stop corrosion in a reliable and economical way where chloride contamination has caused reinforcement corrosion and subsequent concrete damage. To new structures where

  2. Assessment of the cathode contribution to the degradation of anode-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Hagen, Anke; Liu, Yi-Lin; Barfod, Rasmus

    2008-01-01

    of the cathode were strongly dependent on the pO(2). Microstructural analysis of the cathode/electrolyte interface carried out after removal of the cathode showed craters on the electrolyte surface where the lanthanum strontium manganite (LSM) particles had been located. The changes of shape and size......The degradation of anode-supported cells was studied over 1500 h as a function of cell polarization either in air or oxygen on the cathode side. Based on impedance analysis, contributions of the anode and cathode to the increase of total resistance were assigned. Accordingly, the degradation rates...

  3. Methanol-Tolerant Cathode Catalyst Composite For Direct Methanol Fuel Cells

    Science.gov (United States)

    Zhu, Yimin; Zelenay, Piotr

    2006-03-21

    A direct methanol fuel cell (DMFC) having a methanol fuel supply, oxidant supply, and its membrane electrode assembly (MEA) formed of an anode electrode and a cathode electrode with a membrane therebetween, a methanol oxidation catalyst adjacent the anode electrode and the membrane, an oxidant reduction catalyst adjacent the cathode electrode and the membrane, comprises an oxidant reduction catalyst layer of a platinum-chromium alloy so that oxidation at the cathode of methanol that crosses from the anode through the membrane to the cathode is reduced with a concomitant increase of net electrical potential at the cathode electrode.

  4. Lifetime advantage and failure mechanism of a metal-ferroelectric cathode

    Science.gov (United States)

    Wu, Ping; Sun, Jun; Yang, Zhanfeng; Huo, Shaofei; Liu, Wenyuan

    2017-10-01

    The lifetime of explosive emission cathodes is important for high power microwave generators operating in the repetitive regime. For normal metallic cathodes, micropoints on the cathode surface with large field enhancement factors may be gradually consumed in explosive electron emission, which will lead to a limited lifetime. In this paper, a metal-ferroelectric cathode made of stainless steel and BaTiO3 is manufactured. Under voltage close to 1 MV and current near 10 kA, this cathode presents a much longer lifetime than the normal stainless steel cathode, demonstrating the lifetime advantage of the metal-ferroelectric cathode. Nevertheless, in the lifetime experiment of 1.28 × 105 pulses, this metal-ferroelectric cathode also presents obvious lifetime phenomena, one of which is the microwave duration generated by a relativistic backward wave oscillator decreasing from 27 ns to 19 ns. Observation of the cathode surface morphology shows that the emission property deterioration of the metal-ferroelectric cathode may originate from severe ablation of the ferroelectric ceramic layer, which leads to shortening of the ceramic layer relative to the metallic layer. Therefore, choosing the metallic material properly and decreasing the blade thickness of the metallic layer moderately may suppress the relative shortening of the ceramic layer and thus can further lengthen the lifetime of the metal-ferroelectric cathode.

  5. Enhanced catalytic activity and inhibited biofouling of cathode in microbial fuel cells through controlling hydrophilic property

    Science.gov (United States)

    Li, Da; Liu, Jia; Wang, Haiman; Qu, Youpeng; Zhang, Jie; Feng, Yujie

    2016-11-01

    The hydrophilicity of activated carbon cathode directly determines the distribution of three-phase interfaces where oxygen reduction occurs. In this study, activated carbon cathodes are fabricated by using hydrophobic polytetrafluoroethylene (PTFE) and amphiphilic LA132 at various weight ratio to investigate the effect of hydrophilic property on cathode performance. Contact angle tests confirm the positive impact of LA132 content on hydrophilicity. Cathode with 67 wt% LA132 content shows the highest electrochemical activity as exchange current density increases by 71% and charge transfer resistance declines by 44.6% compared to that of PTFE cathode, probably due to the extended reaction interfaces by optimal hydrophilicity of cathode so that oxygen reduction is facilitated. As a result, the highest power density of 1171 ± 71 mW m-2 is obtained which is 14% higher than PTFE cathode. In addition to the hydrophilicity, this cathode had more negative charged surface of catalyst layer, therefore the protein content of cathodic biofilm decreased by 47.5%, indicating the effective bacterial inhibition when 67 wt% LA132 is used. This study shows that the catalytic activity of cathode is improved by controlling proper hydrophilicity of cathode, and that biofilm can be reduced by increasing hydrophilicity and lowering the surface potential.

  6. Morphology and microstructure evolution of Ti-50 at.% Al cathodes during cathodic arc deposition of Ti-Al-N coatings

    Science.gov (United States)

    Syed, Bilal; Zhu, Jianqiang; Polcik, Peter; Kolozsvari, Szilard; Hâkansson, Greger; Johnson, Lars; Ahlgren, Mats; Jöesaar, Mats; Odén, Magnus

    2017-06-01

    Today's research on the cathodic arc deposition technique and coatings therefrom primarily focuses on the effects of, e.g., nitrogen partial pressure, growth temperature, and substrate bias. Detailed studies on the morphology and structure of the starting material—the cathode—during film growth and its influence on coating properties at different process conditions are rare. This work aims to study the evolution of the converted layer, its morphology, and microstructure, as a function of the cathode material grain size during deposition of Ti-Al-N coatings. The coatings were reactively grown in pure N2 discharges from powder metallurgically manufactured Ti-50 at.% Al cathodes with grain size distribution averages close to 1800, 100, 50, and 10 μm, respectively, and characterized with respect to microstructure, composition, and mechanical properties. The results indicate that for the cathode of 1800 μm grain size the disparity in the work function among parent phases plays a dominant role in the pronounced erosion of Al, which yields the coatings rich in macro-particles and of high Al content. We further observed that a reduction in the grain size of Ti-50 at.% Al cathodes to 10 μm provides favorable conditions for self-sustaining reactions between Ti and Al phases upon arcing to form γ phase. The combination of self-sustaining reaction and the arc process not only result in the formation of hole-like and sub-hole features on the converted layer but also generate coatings of high Al content and laden with macro-particles.

  7. Cathode Assessment for Maximizing Current Generation in Microbial Fuel Cells Utilizing Bioethanol Effluent as Substrate

    DEFF Research Database (Denmark)

    Sun, Guotao; Thygesen, Anders; Meyer, Anne S.

    2016-01-01

    Implementation of microbial fuel cells (MFCs) for electricity production requires effective current generation from waste products via robust cathode reduction. Three cathode types using dissolved oxygen cathodes (DOCs), ferricyanide cathodes (FeCs) and air cathodes (AiCs) were therefore assessed...... responses to substrate loading rates and external resistance. At the lowest external resistance of 27 and highest substrate loading rate of 2 g chemical oxygen demand (COD) per Lday, FeC-MFC generated highest average current density (1630 mA/m(2)) followed by AiC-MFC (802 mA/m(2)) and DOC-MFC (184 mA/m(2......)). Electrochemical impedance spectroscopy (EIS) was used to determine the impedance of the cathodes. It was thereby confirmed that the FeC-MFC produced the highest current density with the lowest internal resistance for the cathode. However, in a setup using bioethanol effluent, the AiC-MFC was concluded...

  8. Anode-originated SEI migration contributes to formation of cathode-electrolyte interphase layer

    Science.gov (United States)

    Fang, Shuyu; Jackson, David; Dreibelbis, Mark L.; Kuech, Thomas F.; Hamers, Robert J.

    2018-01-01

    Cathode-electrolyte interphase (CEI) formation is a key process that impacts the performance of lithium-ion batteries. In this work, we characterized the composition and stoichiometry of CEI layer on LiNixMnyCo1-x-yO2 (NMC) cathodes via a novel combination of quantitative correlation analysis of X-ray photoelectron spectra and binder-free cathode formulation. By comparing the CEI formation in NMC-based cells with lithium, graphite and lithium titanate anodes, we demonstrate a CEI formation pathway via migration of surface species that originally formed on the anode side. A case study of cathodes coated by atomic layer deposition with a thin layer of Al2O3 demonstrates that anode-to-cathode migration can be mitigated by ALD cathode coatings. This work highlights the importance of anode-mediated processes in order to correctly interpret surface phenomena on the cathode side and to guide further development of surface protection strategies.

  9. A pore-scale model for the cathode electrode of a proton exchange membrane fuel cell by lattice Boltzmann method

    Energy Technology Data Exchange (ETDEWEB)

    Molaeimanesh, Gholam Reza; Akbari, Mohammad Hadi [Shiraz University, Shiraz (Iran, Islamic Republic of)

    2015-03-15

    A pore-scale model based on the lattice Boltzmann method (LBM) is proposed for the cathode electrode of a PEM fuel cell with heterogeneous and anisotropic porous gas diffusion layer (GDL) and interdigitated flow field. An active approach is implemented to model multi-component transport in GDL, which leads to enhanced accuracy, especially at higher activation over-potentials. The core of the paper is the implementation of an electrochemical reaction with an active approach in a multi-component lattice Boltzmann model for the first time. After model validation, the capability of the presented model is demonstrated through a parametric study. Effects of activation over-potential, pressure differential between inlet and outlet gas channels, land width to channel width ratio, and channel width are investigated. The results show the significant influence of GDL microstructure on the oxygen distribution and current density profile.

  10. The Effect of Inhomogeneous Compression on Water Transport in the Cathode of a Proton Exchange Membrane Fuel Cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Berning, Torsten; Kær, Søren Knudsen

    2012-01-01

    A three-dimensional, multicomponent, two-fluid model developed in the commercial CFD package CFX 13 (ANSYS Inc.) is used to investigate the effect of porous media compression on water transport in a proton exchange membrane fuel cell (PEMFC). The PEMFC model only consist of the cathode channel, gas....... Furthermore, the presence of irreducible liquid water is taken into account. In order to account for compression, porous media morphology variations are specified based on the gas diffusion layer (GDL) through-plane strain and intrusion which are stated as a function of compression. These morphology...... diffusion layer, microporous layer, and catalyst layer, excluding the membrane and anode. In the porous media liquid water transport is described by the capillary pressure gradient, momentum loss via the Darcy-Forchheimer equation, and mass transfer between phases by a nonequilibrium phase change model...

  11. Carbon-Based Air-Breathing Cathodes for Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Irene Merino-Jimenez

    2016-08-01

    Full Text Available A comparison between different carbon-based gas-diffusion air-breathing cathodes for microbial fuel cells (MFCs is presented in this work. A micro-porous layer (MPL based on carbon black (CB and an activated carbon (AC layer were used as catalysts and applied on different supporting materials, including carbon cloth (CC, carbon felt (CF, and stainless steel (SS forming cathode electrodes for MFCs treating urine. Rotating ring disk electrode (RRDE analyses were done on CB and AC to: (i understand the kinetics of the carbonaceous catalysts; (ii evaluate the hydrogen peroxide production; and (iii estimate the electron transfer. CB and AC were then used to fabricate electrodes. Half-cell electrochemical analysis, as well as MFCs continuous power performance, have been monitored. Generally, the current generated was higher from the MFCs with AC electrodes compared to the MPL electrodes, showing an increase between 34% and 61% in power with the AC layer comparing to the MPL. When the MPL was used, the supporting material showed a slight effect in the power performance, being that the CF is more powerful than the CC and the SS. These differences also agree with the electrochemical analysis performed. However, the different supporting materials showed a bigger effect in the power density when the AC layer was used, being the SS the most efficient, with a power generation of 65.6 mW·m−2, followed by the CC (54 mW·m−2 and the CF (44 mW·m−2.

  12. Two-dimensional microgap gas chambers on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Marel, J. van der [Delft Univ. of Technol. (Netherlands). Fac. of Appl. Phys.]|[Delft Univ. of Technol. (Netherlands). Inst. of Microelectron. and Submicrotechnol.; Bogaard, A. van der [Delft Univ. of Technol. (Netherlands). Fac. of Appl. Phys.]|[Delft Univ. of Technol. (Netherlands). Inst. of Microelectron. and Submicrotechnol.; Eijk, C.W.E. van [Delft Univ. of Technol. (Netherlands). Fac. of Appl. Phys.]|[Delft Univ. of Technol. (Netherlands). Inst. of Microelectron. and Submicrotechnol.; Hollander, R.W. [Delft Univ. of Technol. (Netherlands). Fac. of Appl. Phys.]|[Delft Univ. of Technol. (Netherlands). Inst. of Microelectron. and Submicrotechnol.; Sarro, P.M. [Delft Univ. of Technol. (Netherlands). Fac. of Appl. Phys.]|[Delft Univ. of Technol. (Netherlands). Inst. of Microelectron. and Submicrotechnol.

    1995-12-11

    We are manufacturing microgap chambers (MGC) on silicon with two-dimensional read-out. They have an anode pitch of 100 {mu}m and a cathode pitch of 400 {mu}m. We obtained a maximum gas gain of 2500 and the avalanche charge collection takes place within 15 ns. The stability of the gas gain is very good. We have tested the position resolution for the detection of X-rays. It appears that the gas composition and the strength of the drift field are important parameters. A high concentration of dimethylether and a rather small drift field provide the smallst size of the total avalanche. (orig.).

  13. Gas gangrene

    Science.gov (United States)

    Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues; Necrotizing soft tissue infection ... Gas gangrene is most often caused by bacteria called Clostridium perfringens. It also can be caused by ...

  14. Understanding Mn-Based Intercalation Cathodes from Thermodynamics and Kinetics

    Directory of Open Access Journals (Sweden)

    Yin Xie

    2017-07-01

    Full Text Available A series of Mn-based intercalation compounds have been applied as the cathode materials of Li-ion batteries, such as LiMn2O4, LiNi1−x−yCoxMnyO2, etc. With open structures, intercalation compounds exhibit a wide variety of thermodynamic and kinetic properties depending on their crystal structures, host chemistries, etc. Understanding these materials from thermodynamic and kinetic points of view can facilitate the exploration of cathodes with better electrochemical performances. This article reviews the current available thermodynamic and kinetic knowledge on Mn-based intercalation compounds, including the thermal stability, structural intrinsic features, involved redox couples, phase transformations as well as the electrical and ionic conductivity.

  15. The Impact of Strong Cathodic Polarization on SOC Electrolyte Materials

    DEFF Research Database (Denmark)

    Kreka, Kosova; Hansen, Karin Vels; Jacobsen, Torben

    2016-01-01

    of impurities at the grain boundaries, electrode poisoning, delamination or cracks of the electrolyte etc., have been observed in cells operated at such conditions, lowering the lifetime of the cell1,2. High polarizations are observed at the electrolyte/cathode interface of an electrolysis cell operated at high...... current density. In case of a cell voltage above 1.6 V, p-type and n-type electronic conductivity are often observed at the anode and cathode respectively3. Hence, a considerable part of the current is lost as leakage through the electrolyte, thus lowering the efficiency of the cell considerably.......One of the most promising reversible energy conversion/storage technologies is that of Solid Oxide Fuel/Electrolysis Cells (SOFC/SOEC, collectively termed SOC). Long term durability is typically required for such devises to become economically feasible, hence considerable amount of work has...

  16. Plasma jet characteristics in vacuum arc with diffused cathode spot

    Science.gov (United States)

    Amirov, R. Kh; Vorona, N. A.; Gavrikov, A. V.; Liziakin, G. D.; Polistchook, V. P.; Samoylov, I. S.; Smirnov, V. P.; Usmanov, R. A.; Yartsev, I. M.

    2017-05-01

    Diffused vacuum arc, which is characterized by the absence of microparticles in cathode erosion products and by the irregular voltage oscillations, is considered to be a perspective plasma source for plasma reprocessing technology of spent nuclear fuel (SNF). The development of this technology requires data on ions energy in plasma jet. In this work parameters of plasma jet in diffused vacuum arc with a gadolinium cathode were studied by a retarding field analyzer, Langmuir and condensation probes. Gadolinium is regarded as a substance simulating SNF plasma. Ion energy spectrum was studied at arc currents of 30-75 A and voltages of 4-15 V at the distance of 20 cm above the arc anode. Dependencies of spectrum widths and most possible ion energies on arc voltages were obtained. The measured electron temperature was 2 eV, the maximum ion energy reached 70 eV. Experimental data were used to calculate adiabatic plasma expansion through the anode outlet.

  17. Field-emission cathode gating for rf electron guns

    Directory of Open Access Journals (Sweden)

    J. W. Lewellen

    2005-03-01

    Full Text Available We present a novel method of combining the most desirable characteristics of thermionic-cathode and photocathode rf guns, using a field-emission cathode and multiple rf frequencies. Simulations indicate that extremely low-emittance beams (on the order of 2 nm normalized emittance at moderate beam currents (1 mA and beam energies of ∼2  MeV can be obtained using this technique. The resulting gun design promises to be useful as a driver source for a number of applications, including high-voltage electron microscopy, precision electron-beam welding, and long-wavelength (THz radiation generation; we include performance calculations for the electron microscopy and precision welding applications.

  18. Field-emission cathode gating for rf electron guns

    Science.gov (United States)

    Lewellen, J. W.; Noonan, J.

    2005-03-01

    We present a novel method of combining the most desirable characteristics of thermionic-cathode and photocathode rf guns, using a field-emission cathode and multiple rf frequencies. Simulations indicate that extremely low-emittance beams (on the order of 2 nm normalized emittance) at moderate beam currents (1 mA) and beam energies of ˜2 MeV can be obtained using this technique. The resulting gun design promises to be useful as a driver source for a number of applications, including high-voltage electron microscopy, precision electron-beam welding, and long-wavelength (THz) radiation generation; we include performance calculations for the electron microscopy and precision welding applications.

  19. Lithium-ferrate-based cathodes for molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lanagan, M.T.; Wolfenstine, J. [Argonne National Lab., IL (United States). Energy Technology Div.; Bloom, I.; Kaun, T.D.; Krumpelt, M. [Argonne National Lab., IL (United States). Chemical Technology Div.

    1996-12-31

    Argonne National Laboratory is developing advanced cathodes for pressurized operation of the molten carbonate fuel cell (MCFC) at approximately 650 degrees Centigrade. These cathodes are based on lithium ferrate (LiFeO[sub 2]) which is attractive because of its very low solubility in the molten (Li,K)[sub 2]CO[sub 3] electrolyte. Because of its high resistivity, LiFeO[sub 2] cannot be used as a direct substitute for NiO. Cation substitution is, therefore, necessary to decrease resistivity. The effect of cation substitution on the resistivity and deformation of LiFeO[sub 2] was determined. The substitutes were chosen because their respective oxides as well as LiFeO[sub 2] crystallize with the rock-salt structure.

  20. Rechargeable lithium cells with modified vanadium oxide cathodes

    Science.gov (United States)

    Chung, S. K.; Chmilenko, N. A.; Borovykov, A. Ya; Lee, S. H.

    Modified vanadium oxide has been prepared by melting V 2O 5 with additives of 3-3.5% of sodium orthosilicate at 690°C for 3 h followed by fast cooling to an ambient temperature. Charge-discharge characteristics of this oxide were studied as an active cathode material for lithium secondary batteries. The oxide undergoes irreversible transition to become essentially amorphous after first discharge to cut-off voltage of 2 V vs. Li, and then exhibits excellent rechargeability in the 1.5 to 3.9 V potential range. The coin type 2325 size secondary cells have been manufactured and tested with the modified vanadium oxide cathodes and Li-Al alloy anodes. Preliminary shallow cycling modifies the cells' performance and allows to obtain rating capacity 50 mA h in the voltage diapason of 2.0-3.9 V with draining current 0.5 mA.

  1. Cathodic cage nitriding of samples with different dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, R.R.M. de [Centro Federal de Educacao Tecnologica do Piaui, Department of Mechanical, Teresina, PI (Brazil); Araujo, F.O. de [Universidade Federal Rural do Semi-Arido, Mossoro, RN (Brazil); Ribeiro, K.J.B.; Mendes, M.W.D. [Labplasma, Departamento de Fisica-UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Costa, J.A.P. da [Departamento de Fisica-UFC, Fortaleza, CE (Brazil); Alves, C. [Labplasma, Departamento de Fisica-UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)], E-mail: alvesjr@pesquisador.cnpq.br

    2007-09-15

    A series of AISI 1020 steel cylindrical samples with different heights were simultaneously nitrided in cathodic cage plasma nitriding. In this technique, the samples are placed under a floating potential inside a cage in which the cathodic potential is applied. A systematic study of the nitriding temperature variation effects was carried out in order to evaluate the efficiency of such a technique over the uniformity of the formed layers. The samples were characterized by optical microscopy, X-ray diffraction and microhardness measurement. The results were compared with those ones obtained in the ionic nitriding, and was verified that the samples nitrided by this conventional technique presents less uniformity than the ones treated through this new technique.

  2. Multi scale and physics models for intermediate and low temperatures H+-solid oxide fuel cells with H+/e-/O2- mixed conducting properties: Part A, generalized percolation theory for LSCF-SDC-BZCY 3-component cathodes

    Science.gov (United States)

    Chen, Daifen; Zhang, Qiang; Lu, Liu; Periasamy, Vijay; Tade, Moses O.; Shao, Zongping

    2016-01-01

    H+ based solid oxide fuel cell (SOFC) composite cathodes are generally agreed to be of quite different relationships among the microstructure parameters, electrode properties and detailed working processes from the conventional O2--SOFC composite cathodes. In this paper, the percolation theory is significantly generalized and developed to suit most of the typical H+-SOFC composite cathodes with e-/H+, e-/O2- or e-/H+/O2- mixed conducting characteristics; not just limited to the BCZY, SDC and LSCF materials. It provides an easy way to investigate the effect of microstructure parameters on the H+-SOFC electrode characteristics in quantity. The studied electrode properties include: i) the potential coexisting sites of O2, e-, and O2- transport paths for the oxygen reduction; ii) the potential coexisting sites of O2-, H+ and H2O transport paths for the vapor formation; iii) the effective e-, O2-, and H+ conducting and gas diffusing capabilities of the composite cathodes, and so on. It will be helpful for the H+-SOFC composite cathode manufacture to achieve the expected properties. Furthermore, it is also an important step for the developing of the multiphysics-model in manuscript part B to study the effect of the microstructure parameters on the H+-SOFC working details.

  3. Durability and Performance of High Performance Infiltration Cathodes

    DEFF Research Database (Denmark)

    Samson, Alfred Junio; Søgaard, Martin; Hjalmarsson, Per

    2013-01-01

    The performance and durability of solid oxide fuel cell (SOFC) cathodes consisting of a porous Ce0.9Gd0.1O1.95 (CGO) infiltrated with nitrates corresponding to the nominal compositions La0.6Sr0.4Co1.05O3-δ (LSC), LaCoO3-δ (LC), and Co3O4 are discussed. At 600°C, the polarization resistance, Rp...

  4. Unusual Cathode Erosion Patterns Observed for Steered Arc Sources

    CERN Document Server

    Kolbeck, Jonathan

    2014-01-01

    A cathodic arc source with a magnetron-type magnetic field was investigated for stability, erosion, and compatibility with a linear macroparticle filter. Here we report about unusual arc spot erosion patterns, which were narrow (~ 2 mm) with periodic pits when operating in argon, and broad (~ 10 mm) with periodic groves and ridges when operating in an argon and oxygen mixtures. These observations can be correlated with the ignition probability for type 2 and type 1 arc spots, respectively.

  5. Glass Tube Design for CRT(Cathode Ray Tube)

    OpenAIRE

    Junko, ITOH; Keizo, KISHIDA; Koji, NAKAMURA; Masayuki, Miyazaki; Shigeo, OHSUGI; Sumio, YOSHIOKA; Department of Precision Science & Technology, Osaka University; Mitsubishi Elec.Corp.

    2000-01-01

    Stress and deformation of cathode ray tubes(CRTs)under atmospheric pressure and implosion protection band tightening were analyzed using a finite element method(FEM). The stress and deformation of the tubes were measured experimentally by using strain gages and three-dimensional position measuring techniques. The experimental results showed close agreements with those of the simulation. The location of the highest tensile stress and the effects of tightening of the implosion protection bands ...

  6. Plasma gun with coaxial powder feed and adjustable cathode

    Science.gov (United States)

    Zaplatynsky, Isidor (Inventor)

    1991-01-01

    An improved plasma gun coaxially injects particles of ceramic materials having high melting temperatures into the central portion of a plasma jet. This results in a more uniform and higher temperature and velocity distribution of the sprayed particles. The position of the cathode is adjustable to facilitate optimization of the performance of the gun wherein grains of the ceramic material are melted at lower power input levels.

  7. The Effects of Voltage and Concentration of Sodium Bicarbonate on Electrochemical Synthesis of Ethanol from Carbon Dioxide Using Brass as Cathode

    Science.gov (United States)

    Ramadan, Septian; Fariduddin, Sholah; Rizki Aminudin, Afianti; Kurnia Hayatri, Antisa; Riyanto

    2017-11-01

    The effects of voltage and concentration of sodium bicarbonate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide into ethanol. The conversion process is carried out using a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor equipped with a cathode and anode. As the cathode was used brass, while as the anode carbon was utilized. Sample of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced. The optimum electrochemical synthesis conditions to convert carbon dioxide into ethanol are voltage and concentration of sodium bicarbonate are 3 volts and 0.4 M with ethanol concentration of 1.33%.

  8. On the mechanism of the cathode erosion in negative corona discharge

    Science.gov (United States)

    Petrov, Alexey; Amirov, Ravil; Samoylov, Igor

    2009-10-01

    Negative corona discharge was investigated in atmospheric pressure air and SF6 in Trichel pulse and glow mode in point-to-plane electrode configuration. As a cathode pointed carbon, copper and aluminum pins with tip size 0.02-1 mm were used. It is found that negative corona causes the erosion of cathode surface in form of nanometer-size craters and fissures. Observed etching may be explained in terms of microexplosive process. This process is initiated by interaction of the cathode surface with the cathode-directed ionization wave. This wave is registered as a Trichel pulse. Local electric field of the head of wave gives rise to the field emission from the cathode surface which initiates microexplosion due to Joule heating. It is assumed that a single Trichel pulse causes the ejection of an erosion fragment from the cathode surface and current on the cathode surface runs through the cross-section of elementary erosion fragment. The value of Trichel pulse action integral which depends on the cathode current density and pulse duration and serves as a criterion of micro-explosion is 10^9 A^2s/cm^4. Hence the conclusion has been made that erosion of the cathode in Trichel pulse mode of negative corona was caused by microexplosive processes. General erosion picture of the cathode surface depends on the discharge dynamics. Correlation between discharge dynamics, erosion picture and Trichel pulse parameters was found.

  9. Cr(VI) reduction at rutile-catalyzed cathode in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Lu, Anhuai; Ding, Hongrui; Yan, Yunhua; Wang, Changqiu; Zen, Cuiping; Wang, Xin [The Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Jin, Song [MWH Americas, 3665 JFK Parkway, Suite 206, Fort Collins, CO 80525 (United States); Department of Civil and Architectural Engineering, University of Wyoming, Laramie, WY 82071 (United States)

    2009-07-15

    Cathodic reduction of hexavalent chromium (Cr(VI)) and simultaneous power generation were successfully achieved in a microbial fuel cell (MFC) containing a novel rutile-coated cathode. The selected rutile was previously characterized to be sensitive to visible light and capable of both non-photo- and photocatalysis. In the MFCs containing rutile-coated cathode, Cr(VI) was rapidly reduced in the cathode chamber in presence and absence of light irradiation; and the rate of Cr(VI) reduction under light irradiation was substantially higher than that in the dark. Under light irradiation, 97% of Cr(VI) (initial concentration 26 mg/L) was reduced within 26 h, which was 1.6 x faster than that in the dark controls in which only background non-photocatalysis occurred. The maximal potential generated under light irradiation was 0.80 vs. 0.55 V in the dark controls. These results indicate that photocatalysis at the rutile-coated cathode in the MFCs might have lowered the cathodic overpotential, and enhanced electron transfer from the cathode to Cr(VI) for its reduction. In addition, photoexcited electrons generated during the cathode photocatalysis might also have contributed to the higher Cr(VI) reduction rates when under light irradiation. This work assessed natural rutile as a novel cathodic catalyst for MFCs in power generation; particularly it extended the practical merits of conventional MFCs to cathodic reduction of environmental contaminants such as Cr(VI). (author)

  10. Modification of W surfaces by exposure to hollow cathode plasmas

    Science.gov (United States)

    Stancu, C.; Stokker-Cheregi, F.; Moldovan, A.; Dinescu, M.; Grisolia, C.; Dinescu, G.

    2017-10-01

    In this work, we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency plasmas in hollow cathode discharge configuration. Our study addresses issues that relate to the use of W in next-generation fusion reactors and, therefore, the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments, we used commercially available tungsten samples having areas of 30 × 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was measured following plasma exposure times up to 90 min. The analysis of changes in surface morphology was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We discuss the influence of experimental parameters on the changes in surface morphology.

  11. Microbial fuel cell performance with non-Pt cathode catalysts

    Science.gov (United States)

    HaoYu, Eileen; Cheng, Shaoan; Scott, Keith; Logan, Bruce

    Various cathode catalysts prepared from metal porphyrines and phthalocyanines were examined for their oxygen reduction activity in neutral pH media. Electrochemical studies were carried out with metal tetramethoxyphenylporphyrin (TMPP), CoTMPP and FeCoTMPP, and metal phthalocyanine (Pc), FePc, CoPc and FeCuPc, supported on Ketjenblack (KJB) carbon. Iron phthalocyanine supported on KJB (FePc-KJB) carbon demonstrated higher activity towards oxygen reduction than Pt in neutral media. The effect of carbon substrate was investigated by evaluating FePc on Vulcan XC carbon (FePcVC) versus Ketjenblack carbon. FePc-KJB showed higher activity than FePcVC suggesting the catalyst activity could be improved by using carbon substrate with a higher surface area. With FePc-KJB as the MFC cathode catalyst, a power density of 634 mW m -2 was achieved in 50 mM phosphate buffer medium at pH 7, which was higher than that obtained using the precious-metal Pt cathode (593 mW m -2). Under optimum operating conditions (i.e. using a high surface area carbon brush anode and 200 mM PBM as the supporting electrolyte with 1 g L -1 acetate as the substrate), the power density was increased to 2011 mW m -2. This high power output indicates that MFCs with low cost metal macrocycles catalysts is promising in further practical applications.

  12. Boundary element method solution for large scale cathodic protection problems

    Science.gov (United States)

    Rodopoulos, D. C.; Gortsas, T. V.; Tsinopoulos, S. V.; Polyzos, D.

    2017-12-01

    Cathodic protection techniques are widely used for avoiding corrosion sequences in offshore structures. The Boundary Element Method (BEM) is an ideal method for solving such problems because requires only the meshing of the boundary and not the whole domain of the electrolyte as the Finite Element Method does. This advantage becomes more pronounced in cathodic protection systems since electrochemical reactions occur mainly on the surface of the metallic structure. The present work aims to solve numerically a sacrificial cathodic protection problem for a large offshore platform. The solution of that large-scale problem is accomplished by means of “PITHIA Software” a BEM package enhanced by Hierarchical Matrices (HM) and Adaptive Cross Approximation (ACA) techniques that accelerate drastically the computations and reduce memory requirements. The nonlinear polarization curves for steel and aluminium in seawater are employed as boundary condition for the under protection metallic surfaces and aluminium anodes, respectively. The potential as well as the current density at all the surface of the platform are effectively evaluated and presented.

  13. X-Band Thermionic Cathode RF Gun at UTNL

    CERN Document Server

    Fukasawa, Atsushi; Dobashi, Katsuhiro; Ebina, Futaro; Hayano, Hitoshi; Higo, Toshiyasu; Kaneyasu, Tatsuo; Matsuo, Kennichi; Ogino, Haruyuki; Sakae, Hisaharu; Sakamoto, Fumito; Uesaka, Mitsuru; Urakawa, Junji

    2005-01-01

    The X-band (11.424 GHz) linac for compact Compton scattering hard X-ray source are under construction at Nuclear Engineering Research Laboratory, University of Tokyo. This linac designed to accelerate up to 35 MeV, and this electron beam will be used to produce hard X-ray by colliding with laser. It consists of a thermionic cathode RF gun, an alpha magnet, and a traveling wave tube. The gun has 3.5 cells (unloaded Q is 8250) and will be operated at pi-mode. A dispenser cathode is introduced. Since the energy spread of the beam from the gun is predicted to be broad due to the continuous emission from the thermionic cathode, a slit is placed in the alpha magnet to eliminate low energy electrons. The simulation on the injector shows the beam energy 2.9 MeV, the charge 23 pC/bunch, and the emittance less than 10 mm.mrad. The experiment on the gun is planed in the beginning of 2005, and the details will be discussed on the spot.

  14. Patterning of dispenser cathode surfaces to a controlled porosity

    Science.gov (United States)

    Garner, Charles E.; Deininger, William D.; Gibson, John; Thomas, Richard

    1989-01-01

    A process to pattern slots approximately 1.25 microns in width into 25-micron-thick W films that have been deposited onto flat or concave surfaces is discussed. A 25-micron-thick W film with a high degree of (100) orientation is chemically vapor deposited (CVD) onto a flat or concave Mo mandrel. A 5-micron-thick Al film is deposited onto the CVD W, followed by 2 microns of photoresist. On concave cathodes, XeCl2 laser ablation or X-ray lithography is used to pattern the photoresist, whereas on flat cathodes deep UV lithography can be used. The patterned photoresist serves as the mask in a Cl ion-beam-assisted etching (IBAE) process to pattern the Al. An alternative process is to deposit Al2O3 films onto the W and pattern the Al2O3 using laser ablation. The W film is then patterned to 3-6-micron slot widths using IBAE + ClF3 with the patterned Al or Al2O3 as the mask. Finally, a sputter deposition step is required to close up the slots to approximately 1 micron. The process described is capable of patterning concave dispenser cathodes to a controlled and precise porosity.

  15. Ion velocities in a micro-cathode arc thruster

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang Taisen; Shashurin, Alexey; Keidar, Michael [The George Washington University, Washington, DC 22202 (United States); Beilis, Isak [Tel Aviv University, Tel Aviv (Israel)

    2012-06-15

    Ion velocities in the plasma jet generated by the micro-cathode arc thruster are studied by means of time-of-flight method using enhanced ion detection system (EIDS). The EIDS triggers perturbations (spikes) on arc current waveform, and the larger current in the spike generates denser plasma bunches propagating along with the mainstream plasma. The EIDS utilizes double electrostatic probes rather than single probes. The average Ti ion velocity is measured to be around 2 Multiplication-Sign 10{sup 4} m/s without a magnetic field. It was found that the application of a magnetic field does not change ion velocities in the interelectrode region while leads to ion acceleration in the free expanding plasma plume by a factor of about 2. Ion velocities of about 3.5 Multiplication-Sign 10{sup 4} m/s were detected for the magnetic field of about 300 mT at distance of about 100-200 mm from the cathode. It is proposed that plasma is accelerated due to Lorentz force. The average thrust is calculated using the ion velocity measurements and the cathode mass consumption rate, and its increase with the magnetic field is demonstrated.

  16. High-Capacity, High-Voltage Composite Oxide Cathode Materials

    Science.gov (United States)

    Hagh, Nader M.

    2015-01-01

    This SBIR project integrates theoretical and experimental work to enable a new generation of high-capacity, high-voltage cathode materials that will lead to high-performance, robust energy storage systems. At low operating temperatures, commercially available electrode materials for lithium-ion (Li-ion) batteries do not meet energy and power requirements for NASA's planned exploration activities. NEI Corporation, in partnership with the University of California, San Diego, has developed layered composite cathode materials that increase power and energy densities at temperatures as low as 0 degC and considerably reduce the overall volume and weight of battery packs. In Phase I of the project, through innovations in the structure and morphology of composite electrode particles, the partners successfully demonstrated an energy density exceeding 1,000 Wh/kg at 4 V at room temperature. In Phase II, the team enhanced the kinetics of Li-ion transport and electronic conductivity at 0 degC. An important feature of the composite cathode is that it has at least two components that are structurally integrated. The layered material is electrochemically inactive; however, upon structural integration with a spinel material, the layered material can be electrochemically activated and deliver a large amount of energy with stable cycling.

  17. Development of improved cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, H.U.

    1991-03-01

    The University of Missouri-Rolla conducted a 17 month research program focused on the development and evaluation of improved cathode materials for solid oxide fuel cells (SOFC). The objectives of this program were: (1) the development of cathode materials of improved stability in reducing environments; and (2) the development of cathode materials with improved electrical conductivity. The program was successful in identifying some potential candidate materials: Air sinterable (La,Ca)(Cr,Co)O{sub 3} compositions were developed and found to be more stable than La{sub .8}Sr{sub .2}MnO{sub 3} towards reduction. Their conductivity at 1000{degrees}C ranged between 30 to 60 S/cm. Compositions within the (Y,Ca)(Cr,Co,Mn)O{sub 3} system were developed and found to have higher electrical conductivity than La{sub .8}Sr{sub .2}MnO{sub 3} and preliminary results suggest that their stability towards reduction is superior.

  18. Ruslands Gas

    OpenAIRE

    Elkjær, Jonas Bondegaard

    2008-01-01

    This paper is about Russian natural gas and the possibility for Russia to use its reserves of natural gas politically towards the European Union to obtain some political power. Russia owns 32,1 % of the world gas reserves, and The European Union is getting 50 % of its gas import from Russia. I will use John Mearsheimer’s theory ”The Tragedy of Great Power Politics” to explain how Russia can use its big reserves of gas on The European Union to get political influence.

  19. A Systematic Cathode Study-Activation of a Thermionic Cathode, and Measuring Cesium Evaporation from a Dispenser Photocathode

    Science.gov (United States)

    2010-06-01

    Unit Å Ångstrom ( 10-10 m) BAG Bayard-Alpert Gauge Bi Bismuth CCG Cold Cathode Gauge conflat The standard UHV flange-to-flange interface...the form of hydroxide groups. In layman’s terms a hydroxide (hydrated water) is formed when water molecules take up residence in the housing...structure of a crystal lattice—molecular squatters in a sense. More formally, a hydroxide is a compound with H2O molecules loosely associated with it

  20. Post-Removal Examination of GTF Cathode #3

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, R.

    2005-01-31

    This photo-cathode (PC), Gun Test Facility (GTF) Cathode No.3, was removed from the GTF injector, after operation, in March, 2003 (report LCLS-TN-03-1). It was examined originally by secondary electron microscopy in October, 2000, after polishing and degreasing, prior to insertion into the GTF injector. Images of the PC prior to insertion into the rf gun and after running are included in this report. The cathode fabrication and preparation steps were: The cathode plate was conventionally-machined at SLAC, using class one OFE copper plate from Klystron Dept stock. A centrally-located ten mm through-hole was produced, and the plate was then cleaned in the SLAC Plating Shop (procedure C01A, no Oxyban). A tuning rod attachment nut was then 35-65 Au/Cu-brazed to the rear of the plate for in-situ attachment to the GTF transfer/tuning rod. A two mm-thick (100) single-crystal ten mm diameter Cu disk-insert was oriented with Laue x-ray diffraction, and Au/Cu-brazed into the hole with Au/Cu. The plate was then polished to smooth flatness by J. Francis, initially using SiC and, finally, 0.25 micron diamond paste. The plate was then solvent-degreased, face-down on teflon edge supports with hot TCE, acetone and ethanol. The cathode surface was then imaged in the SEM and installed into the GTF rf gun. This report covers the surface appearance before and after GTF running. It will address the following: What is the general surface condition as a result of running? What is the distribution of debris and breakdown features? Is breakdown activity enhanced at the braze line or at the voids in the braze line? Has rf heating, although minimal, affected the surface/braze line, perhaps through thermal expansion? And finally, is laser or ion-feedback damage visible at the single crystal center and what is its nature?

  1. Ecton processes in the generation of pulsed runaway electron beams in a gas discharge

    Science.gov (United States)

    Mesyats, G. A.

    2017-09-01

    As was shown earlier for pulsed discharges that occur in electric fields rising with extremely high rates (1018 V/(cm s)) during the pulse rise time, the electron current in a vacuum discharge is lower than the current of runaway electrons in an atmospheric air discharge in a 1-cm-long gap. In this paper, this is explained by that the field emission current from cathode microprotrusions in a gas discharge is enhanced due to gas ionization. This hastens the initiation of explosive electron emission, which occurs within 10-11 s at a current density of up to 1010 A/cm2. Thereafter, a first-type cathode spot starts forming. The temperature of the cathode spot decreases due to heat conduction, and the explosive emission current ceases. Thus, the runaway electron current pulse is similar in nature to the ecton phenomenon in a vacuum discharge.

  2. Binder-free V2O5 cathode for greener rechargeable aluminum battery.

    Science.gov (United States)

    Wang, Huali; Bai, Ying; Chen, Shi; Luo, Xiangyi; Wu, Chuan; Wu, Feng; Lu, Jun; Amine, Khalil

    2015-01-14

    This letter reports on the investigation of a binder-free cathode material to be used in rechargeable aluminum batteries. This cathode is synthesized by directly depositing V2O5 on a Ni foam current collector. Rechargeable aluminum coin cells fabricated using the as-synthesized binder-free cathode delivered an initial discharge capacity of 239 mAh/g, which is much higher than that of batteries fabricated using a cathode composed of V2O5 nanowires and binder. An obvious discharge voltage plateau appeared at 0.6 V in the discharge curves of the Ni-V2O5 cathode, which is slightly higher than that of the V2O5 nanowire cathodes with common binders. This improvement is attributed to reduced electrochemical polarization.

  3. Characterization of Atomic and Electronic Structures of Electrochemically Active SOFC Cathode Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Blinn; Yongman Choi; Meilin Liu

    2009-08-11

    The objective of this project is to gain a fundamental understanding of the oxygen-reduction mechanism on mixed conducting cathode materials by means of quantum-chemical calculations coupled with direct experimental measurements, such as vibrational spectroscopy. We have made progress in the elucidation of the mechanisms of oxygen reduction of perovkite-type cathode materials for SOFCs using these quantum chemical calculations. We established computational framework for predicting properties such as oxygen diffusivity and reaction rate constants for adsorption, incorporation, and TPB reactions, and formulated predictions for LSM- and LSC-based cathode materials. We have also further developed Raman spectroscopy as well as SERS as a characterization tool for SOFC cathode materials. Raman spectroscopy was used to detect chemical changes in the cathode from operation conditions, and SERS was used to probe for pertinent adsorbed species in oxygen reduction. However, much work on the subject of unraveling oxygen reduction for SOFC cathodes remains to be done.

  4. Solid Oxide Fuel Cell Cathodes. Unraveling the Relationship Between Structure, Surface Chemistry and Oxygen Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, Srikanth [Boston Univ., MA (United States)

    2013-03-31

    In this work we have considered oxygen reduction reaction on LSM and LSCF cathode materials. In particular we have used various spectroscopic techniques to explore the surface composition, transition metal oxidation state, and the bonding environment of oxygen to understand the changes that occur to the surface during the oxygen reduction process. In a parallel study we have employed patterned cathodes of both LSM and LSCF cathodes to extract transport and kinetic parameters associated with the oxygen reduction process.

  5. A study of the properties of chlorine dioxide gas as a fumigant.

    Science.gov (United States)

    Shirasaki, Yasufumi; Matsuura, Ayumi; Uekusa, Masashi; Ito, Yoshihiro; Hayashi, Toshiaki

    2016-07-29

    Chlorine dioxide (ClO2) is a strong oxidant that possesses an antimicrobial activity. We demonstrated here that ClO2 gas is easily generated by mixing 3.35% sodium chlorite solution (Purogene) and 85% phosphoric acid at a 10:1 volume ratio without using an expensive machine. In a test room (87 m(3)), experiments were carried out using various amounts of sodium chlorite solution (0.25 ml/m(3) to 20.0 ml/m(3)). The gas concentration increased in a sodium chlorite volume-dependent manner and reached peak values of from 0.8 ppm to 40.8 ppm at 2 h-3 h, and then gradually decreased. No differences in gas concentrations were observed between 0.1 and 2.5 m above the floor, indicating that the gas was evenly distributed. Under high-humidity (approximately 80% relative humidity), colony formation of both Staphylococcus aureus and Escherichia coli was completely inhibited by ClO2 gas exposure at 1.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 3.0 ppm). Exposure at 4.0 ml/m(3) sodium chlorite solution (mean maximal concentration of 10.6 ppm) achieved complete inactivation of Bacillus atrophaeus spores. In contrast, without humidification, the efficacy of ClO2 gas was apparently attenuated, suggesting that the atmospheric moisture is indispensable. Delicate electronic devices (computer, camera, etc.) operated normally, even after being subjected to more than 20 times of fumigation. Considering that our method for gas generation is simple, reproducible, and highly effective at decontaminating microbes, our approach is expected to serve as an inexpensive alternative method for cleaning and disinfecting animal facilities.

  6. Requirements for gas quality and gas appliances

    NARCIS (Netherlands)

    Levinsky, Howard; Gersen, Sander; Kiewiet, Bert

    2015-01-01

    Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion

  7. Methods and apparatuses for making cathodes for high-temperature, rechargeable batteries

    Science.gov (United States)

    Meinhardt, Kerry D; Sprenkle, Vincent L; Coffey, Gregory W

    2014-05-20

    The approaches for fabricating cathodes can be adapted to improve control over cathode composition and to better accommodate batteries of any shape and their assembly. For example, a first solid having an alkali metal halide, a second solid having a transition metal, and a third solid having an alkali metal aluminum halide are combined into a mixture. The mixture can be heated in a vacuum to a temperature that is greater than or equal to the melting point of the third solid. When the third solid is substantially molten liquid, the mixture is compressed into a desired cathode shape and then cooled to solidify the mixture in the desired cathode shape.

  8. Fundamental Investigations and Rational Design of Durable High-Performance SOFC Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu [Georgia Inst. of Technology, Atlanta, GA (United States); Ding, Dong [Georgia Inst. of Technology, Atlanta, GA (United States); Wei, Tao [Georgia Inst. of Technology, Atlanta, GA (United States); Liu, Meilin [Georgia Inst. of Technology, Atlanta, GA (United States)

    2016-03-31

    The main objective of this project is to unravel the degradation mechanism of LSCF cathodes under realistic operating conditions with different types of contaminants, aiming towards the rational design of cathodes with high-performance and enhanced durability by combining a porous backbone (such as LSCF) with a thin catalyst coating. The mechanistic understanding will help us to optimize the composition and morphology of the catalyst layer and microstructure of the LSCF backbone for better performance and durability. More specifically, the technical objectives include: (1) to unravel the degradation mechanism of LSCF cathodes under realistic operating conditions with different types of contaminants using in situ and ex situ measurements performed on specially-designed cathodes; (2) to examine the microstructural and compositional evolution of LSCF cathodes as well as the cathode/electrolyte interfaces under realistic operating conditions; (3) to correlate the fuel cell performance instability and degradation with the microstructural and morphological evolution and surface chemistry change of the cathode under realistic operating conditions; (4) to explore new catalyst materials and electrode structures to enhance the stability of the LSCF cathode under realistic operating conditions; and (5) to validate the long term stability of the modified LSCF cathode in commercially available cells under realistic operating conditions. We have systematically evaluated LSCF cathodes in symmetrical cells and anode supported cells under realistic conditions with different types of contaminants such as humidity, CO2, and Cr. Electrochemical models for the design of test cells and understanding of mechanisms have been developed for the exploration of fundamental properties of electrode materials. It is demonstrated that the activity and stability of LSCF cathodes can be degraded by the introduction of contaminants. The microstructural and compositional evolution of LSCF

  9. On the actual cathode mixed potential in direct methanol fuel cells

    Science.gov (United States)

    Zago, M.; Bisello, A.; Baricci, A.; Rabissi, C.; Brightman, E.; Hinds, G.; Casalegno, A.

    2016-09-01

    Methanol crossover is one of the most critical issues hindering commercialization of direct methanol fuel cells since it leads to waste of fuel and significantly affects cathode potential, forming a so-called mixed potential. Unfortunately, due to the sluggish anode kinetics, it is not possible to obtain a reliable estimation of cathode potential by simply measuring the cell voltage. In this work we address this limitation, quantifying the mixed potential by means of innovative open circuit voltage (OCV) tests with a methanol-hydrogen mixture fed to the anode. Over a wide range of operating conditions, the resulting cathode overpotential is between 250 and 430 mV and is strongly influenced by methanol crossover. We show using combined experimental and modelling analysis of cathode impedance that the methanol oxidation at the cathode mainly follows an electrochemical pathway. Finally, reference electrode measurements at both cathode inlet and outlet provide a local measurement of cathode potential, confirming the reliability of the innovative OCV tests and permitting the evaluation of cathode potential up to typical operating current. At 0.25 A cm-2 the operating cathode potential is around 0.85 V and the Ohmic drop through the catalyst layer is almost 50 mV, which is comparable to that in the membrane.

  10. High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode.

    Science.gov (United States)

    Li, Qing; Wang, Tanyuan; Havas, Dana; Zhang, Hanguang; Xu, Ping; Han, Jiantao; Cho, Jaephil; Wu, Gang

    2016-11-01

    Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.

  11. Nitriding using cathodic cage technique of martensitic stainless steel AISI 420 with addition of CH4

    National Research Council Canada - National Science Library

    De Sousa, R.R.M; De Araújo, F.O; Da Costa, J.A.P; De Sousa, R.S; Alves JR, C

    2008-01-01

    AISI 420 martensitic stainless steel samples were nitrided by cathodic cage technique with addition of methane in the atmosphere aiming to reduce chromium nitride precipitation, to increase hardness...

  12. Preliminary investigation of an improved metal-dielectric cathode for magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Zhang, Xiaoping; Dang, Fangchao; Zhang, Jun; Fan, Yuwei; Li, Zhiqiang

    2015-02-01

    In order to explore the cathode with good repetition quality for the magnetically insulated transmission line oscillators, an improved metal-dielectric cathode is proposed and investigated experimentally. The cathode is designed to be step-like shape, and thin copper plated boards are periodically and compactly arrayed on the surface of the cathode base, which ensures the uniformity of the electrons emitted from the cusps of the copper plated boards. According to the numerical simulation results, the step-like shape is beneficial to convert the kinetic energy of the magnetic insulating current partially and enhance the beam-wave interaction efficiency. Finally, a preliminary experiment of an L-band magnetically insulated transmission line oscillator (MILO) with the improved metal-dielectric cathode is carried out. A high power microwave (HPM) with an average power of 1.95 GW is generated from the MILO, with an efficiency of 13.5%. Under the same experiment condition, the output power and main frequency with the presented cathode are almost the same to those with the velvet cathode. Apart from that, metal-dielectric cathode has the merits of small outgassing and long lifetime, and all of these make the improved metal-dielectric cathode significantly promising for the MILO repetition operation.

  13. Performance of the Cathodes with Trapezoidal Protrusions in Aluminum Electrolysis Cells

    Science.gov (United States)

    Song, Yang; Peng, Jianping; Di, Yuezhong; Wang, Yaowu; Feng, Naixiang

    2017-12-01

    Trapezoidal protrusions were added onto flat cathodes with the objective of enhancing the flow resistance to the metal in aluminum electrolysis cells. This design was tested for 8 months and proved to be effective in reducing cell voltage. Subsequently, trials revealed that when all the protrusions were widened, the energy consumption was barely influenced. Moreover, in the case of flat cathodes alternating with cathodes with widened protrusions, collector bars embedded in the flat cathodes took more current. In this paper, through finite element analysis, protrusions of various arrangements and widths were considered to estimate the current density and velocity in the metal.

  14. Factors influencing the performances of micro-strips gas chambers

    Energy Technology Data Exchange (ETDEWEB)

    Mack, V.; Brom, J.M.; Fang, R.; Fontaine, J.C.; Huss, D.; Kachelhoffer, T.; Kettunen, H.; Levy, J.M.; Pallares, A.; Bergdolt, A.M.; Cailleret, J.; Christophel, E.; Coffin, J.; Eberle, H.; Osswald, F.; Sigward, M.H. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Barthe, S.; Schunck, J.P. [Laboratoire PHASE, 67 - Strasbourg (France)

    1995-12-31

    Damages to MSGCs (Micro-Strips Gas Chambers) induced by discharges have been investigated. Optimization of electrode shapes and/or deposition of a protective coating allows the potential difference between anode and cathode, thus increasing the gain. For prototypes of MSGCs made at the Centre de Recherches Nucleaires, each step of the manufacturing processes was carefully controlled. Results are presented on the influence of cleaning processes on the surface resistance of glass substrates. (author). 21 refs., 8 figs., 2 tabs.

  15. Gas separating

    Science.gov (United States)

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  16. Combinatorial discovery of new methanol-tolerant non-noble metal cathode electrocatalysts for direct methanol fuel cells.

    Science.gov (United States)

    Yu, Jong-Sung; Kim, Min-Sik; Kim, Jung Ho

    2010-12-14

    Combinatorial synthesis and screening were used to identify methanol-tolerant non-platinum cathode electrocatalysts for use in direct methanol fuel cells (DMFCs). Oxygen reduction consumes protons at the surface of DMFC cathode catalysts. In combinatorial screening, this pH change allows one to differentiate active catalysts using fluorescent acid-base indicators. Combinatorial libraries of carbon-supported catalyst compositions containing Ru, Mo, W, Sn, and Se were screened. Ternary and quaternary compositions containing Ru, Sn, Mo, Se were more active than the "standard" Alonso-Vante catalyst, Ru(3)Mo(0.08)Se(2), when tested in liquid-feed DMFCs. Physical characterization of the most active catalysts by powder X-ray diffraction, gas adsorption, and X-ray photoelectron spectroscopy revealed that the predominant crystalline phase was hexagonal close-packed (hcp) ruthenium, and showed a surface mostly covered with oxide. The best new catalyst, Ru(7.0)Sn(1.0)Se(1.0), was significantly more active than Ru(3)Se(2)Mo(0.08), even though the latter contained smaller particles.

  17. Nonlinear observation of internal states of fuel cell cathode utilizing a high-order sliding-mode algorithm

    Science.gov (United States)

    Xu, Liangfei; Hu, Junming; Cheng, Siliang; Fang, Chuan; Li, Jianqiu; Ouyang, Minggao; Lehnert, Werner

    2017-07-01

    A scheme for designing a second-order sliding-mode (SOSM) observer that estimates critical internal states on the cathode side of a polymer electrolyte membrane (PEM) fuel cell system is presented. A nonlinear, isothermal dynamic model for the cathode side and a membrane electrolyte assembly are first described. A nonlinear observer topology based on an SOSM algorithm is then introduced, and equations for the SOSM observer deduced. Online calculation of the inverse matrix produces numerical errors, so a modified matrix is introduced to eliminate the negative effects of these on the observer. The simulation results indicate that the SOSM observer performs well for the gas partial pressures and air stoichiometry. The estimation results follow the simulated values in the model with relative errors within ± 2% at stable status. Large errors occur during the fast dynamic processes (<1 s). Moreover, the nonlinear observer shows good robustness against variations in the initial values of the internal states, but less robustness against variations in system parameters. The partial pressures are more sensitive than the air stoichiometry to system parameters. Finally, the order of effects of parameter uncertainties on the estimation results is outlined and analyzed.

  18. High catalytic activity and pollutants resistivity using Fe-AAPyr cathode catalyst for microbial fuel cell application

    Science.gov (United States)

    Santoro, Carlo; Serov, Alexey; Villarrubia, Claudia W. Narvaez; Stariha, Sarah; Babanova, Sofia; Artyushkova, Kateryna; Schuler, Andrew J.; Atanassov, Plamen

    2015-11-01

    For the first time, a new generation of innovative non-platinum group metal catalysts based on iron and aminoantipyrine as precursor (Fe-AAPyr) has been utilized in a membraneless single-chamber microbial fuel cell (SCMFC) running on wastewater. Fe-AAPyr was used as an oxygen reduction catalyst in a passive gas-diffusion cathode and implemented in SCMFC design. This catalyst demonstrated better performance than platinum (Pt) during screening in “clean” conditions (PBS), and no degradation in performance during the operation in wastewater. The maximum power density generated by the SCMFC with Fe-AAPyr was 167 ± 6 μW cm-2 and remained stable over 16 days, while SCMFC with Pt decreased to 113 ± 4 μW cm-2 by day 13, achieving similar values of an activated carbon based cathode. The presence of S2- and showed insignificant decrease of ORR activity for the Fe-AAPyr. The reported results clearly demonstrate that Fe-AAPyr can be utilized in MFCs under the harsh conditions of wastewater.

  19. Development and evaluation of carbon and binder loading in low-cost activated carbon cathodes for air-cathode microbial fuel cells

    KAUST Repository

    Wei, Bin

    2012-01-01

    Activated carbon (AC) air cathodes were constructed using variable amounts of carbon (43-171 mg cm-2) and an inexpensive binder (10 wt% polytetrafluoroethylene, PTFE), and with or without a porous cloth wipe-based diffusion layer (DL) that was sealed with PDMS. The cathodes with the highest AC loading of 171 mg cm-2, and no diffusion layer, produced 1255 ± 75 mW m-2 and did not appreciably vary in performance after 1.5 months of operation. Slightly higher power densities were initially obtained using 100 mg cm-2 of AC (1310 ± 70 mW m-2) and a PDMS/wipe diffusion layer, although the performance of this cathode decreased to 1050 ± 70 mW m-2 after 1.5 months, and 1010 ± 190 mW m-2 after 5 months. AC loadings of 43 mg cm-2 and 100 mg cm-2 did not appreciably affect performance (with diffusion layers). MFCs with the Pt catalyst and Nafion binder initially produced 1295 ± 13 mW m-2, but the performance decreased to 930 ± 50 mW m -2 after 1.5 months, and then to 890 ± 20 mW m-2 after 5 months. Cathode performance was optimized for all cathodes by using the least amount of PTFE binder (10%, in tests using up to 40%). These results provide a method to construct cathodes for MFCs that use only inexpensive AC and a PTFE, while producing power densities similar to those of Pt/C cathodes. The methods used here to make these cathodes will enable further tests on carbon materials in order to optimize and extend the lifetime of AC cathodes in MFCs. © 2012 The Royal Society of Chemistry.

  20. The gas electron multiplier (GEM)

    CERN Document Server

    Bouclier, Roger; Dominik, Wojciech; Hoch, M; Labbé, J C; Million, Gilbert; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe operating priciples and results obtained with a new detector component: the Gas Electrons Multiplier (GEM). Consisting of a thin composite sheet with two metal layers separated by a thin insulator, and pierced by a regular matrix of open channels, the GEM electrode, inserted on the path of electrons in a gas detector, allows to transfer the charge with an amplification factor approaching ten. Uniform response and high rate capability are demonstrated. Coupled to another device, multiwire or micro-strip chamber, the GEM electrode permit to obtain higher gains or less critical operation; separation of the sensitive (conversion) volume and the detection volume has other advantages, as a built-in delay (useful for triggering purposes) and the possibility of applying high fields on the photo-cathode of ring imaging detectors to improve efficiency. Multiple GEM grids in the same gas volume allow to obtain large amplification factors in a succession of steps, leading to the realization of an effective ga...

  1. Microbial fuel cell performance with non-Pt cathode catalysts

    Energy Technology Data Exchange (ETDEWEB)

    HaoYu, Eileen; Scott, Keith [School of Chemical Engineering and Advanced Materials, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Cheng, Shaoan; Logan, Bruce [Department of Civil and Environmental Engineering, The Penn State Hydrogen Energy (H{sub 2}E) Center, Penn State University, University Park, PA 16802 (United States)

    2007-09-27

    Various cathode catalysts prepared from metal porphyrines and phthalocyanines were examined for their oxygen reduction activity in neutral pH media. Electrochemical studies were carried out with metal tetramethoxyphenylporphyrin (TMPP), CoTMPP and FeCoTMPP, and metal phthalocyanine (Pc), FePc, CoPc and FeCuPc, supported on Ketjenblack (KJB) carbon. Iron phthalocyanine supported on KJB (FePc-KJB) carbon demonstrated higher activity towards oxygen reduction than Pt in neutral media. The effect of carbon substrate was investigated by evaluating FePc on Vulcan XC carbon (FePcVC) versus Ketjenblack carbon. FePc-KJB showed higher activity than FePcVC suggesting the catalyst activity could be improved by using carbon substrate with a higher surface area. With FePc-KJB as the MFC cathode catalyst, a power density of 634 mW m{sup -2} was achieved in 50 mM phosphate buffer medium at pH 7, which was higher than that obtained using the precious-metal Pt cathode (593 mW m{sup -2}). Under optimum operating conditions (i.e. using a high surface area carbon brush anode and 200 mM PBM as the supporting electrolyte with 1 g L{sup -1} acetate as the substrate), the power density was increased to 2011 mW m{sup -2}. This high power output indicates that MFCs with low cost metal macrocycles catalysts is promising in further practical applications. (author)

  2. Depolarized SnO2-based gas anodes for electrowinning of silver in molten chlorides

    Directory of Open Access Journals (Sweden)

    Xiao S.

    2013-01-01

    Full Text Available SnO2-based porous anodes were prepared and the behavior of gas bubbles on the porous anodes with different original coarse grain size, immersed in ethanol to simulate molten chlorides, was primarily investigated. SnO2-based porous anodes were used as gas anodes for the electrowinning of silver in CaCl2-NaCl-CaO-AgCl melts at 680°C. Hydrogen was introduced to the anode/electrolyte interface through the gas anode. Carbon was used as the cathode. Obvious depolarization of the anode potential was observed after the introduction of hydrogen comparing with no reducing gas introduced, indicating the involvement of hydrogen in the anode reaction. Metallic silver was deposited on the cathode.

  3. High Performance Infiltrated Backbones for Cathode-Supported SOFC's

    DEFF Research Database (Denmark)

    Gil, Vanesa; Kammer Hansen, Kent

    2014-01-01

    A four-step infiltration method has been developed to infiltrate La0.75Sr0.25MnO3+δ (LSM25) nanoparticles into porous structures (YSZ or LSM-YSZ backbones). The pore size distribution in the backbones is obtained either by using PMMA and/or graphites as pore formers or by leaching treatment of sa...... of samples with Ni remained in the YSZ structure at high temperatures. All impregnated backbones, presented Rs comparable to a standard screen printed cathode, which proves that LSM nanoparticles forms a pathway for electron conduction....

  4. Ultrasonic-assisted cathodic electrochemical discharge for graphene synthesis.

    Science.gov (United States)

    Van Thanh, Dang; Oanh, Phung Phi; Huong, Do Tra; Le, Phuoc Huu

    2017-01-01

    We present a novel and highly efficient method for exfoliating of graphite to produce graphene via the synergistic effects of in-situ plasma induced electrochemical exfoliation with ultrasonic energy, called ultrasonic-assisted cathodic electrochemical discharge. This method can work at moderate temperatures without the need of acidic media or expensive ionic electrolyte. The produced graphene exhibited a large lateral dimension of approximately 6μm and a thickness of 2.5nm, corresponding to approximately seven layers of graphene. An exfoliating mechanism of graphite to produce graphene sheets is also proposed in this study. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Battery designs with high capacity anode materials and cathode materials

    Science.gov (United States)

    Masarapu, Charan; Anguchamy, Yogesh Kumar; Han, Yongbong; Deng, Haixia; Kumar, Sujeet; Lopez, Herman A.

    2017-10-03

    Improved high energy capacity designs for lithium ion batteries are described that take advantage of the properties of high specific capacity anode active compositions and high specific capacity cathode active compositions. In particular, specific electrode designs provide for achieving very high energy densities. Furthermore, the complex behavior of the active materials is used advantageously in a radical electrode balancing design that significantly reduced wasted electrode capacity in either electrode when cycling under realistic conditions of moderate to high discharge rates and/or over a reduced depth of discharge.

  6. Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; 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Serin, M; Sever, R; Surat, U E; Zeyrek, M; Deliomeroglu, M; Demir, D; Gülmez, E; Halu, A; Isildak, B; Kaya, M; Kaya, O; Ozkorucuklu, S; Sonmez, N; Levchuk, L; Lukyanenko, S; Soroka, D; Zub, S; Bostock, F; Brooke, J J; Cheng, T L; Cussans, D; Frazier, R; Goldstein, J; Grant, N; Hansen, M; Heath, G P; Heath, H F; Hill, C; Huckvale, B; Jackson, J; Mackay, C K; Metson, S; Newbold, D M; Nirunpong, K; Smith, V J; Velthuis, J; Walton, R; Bell, K W; Brew, C; Brown, R M; Camanzi, B; Cockerill, D J A; Coughlan, J A; Geddes, N I; Harder, K; Harper, S; Kennedy, B W; Murray, P; Shepherd-Themistocleous, C H; Tomalin, I R; Williams, J H; Womersley, W J; Worm, S D; Bainbridge, R; Ball, G; Ballin, J; Beuselinck, R; Buchmuller, O; Colling, D; Cripps, N; Davies, G; Della Negra, M; Foudas, C; Fulcher, J; Futyan, D; Hall, G; Hays, J; Iles, G; Karapostoli, G; MacEvoy, B C; Magnan, A M; Marrouche, J; Nash, J; Nikitenko, A; Papageorgiou, A; Pesaresi, M; Petridis, K; Pioppi, M; Raymond, D M; Rompotis, N; Rose, A; Ryan, M J; Seez, C; Sharp, P; Sidiropoulos, G; Stettler, M; Stoye, M; Takahashi, M; Tapper, A; Timlin, C; Tourneur, S; Vazquez Acosta, M; Virdee, T; Wakefield, S; Wardrope, D; Whyntie, T; Wingham, M; Cole, J E; Goitom, I; Hobson, P R; Khan, A; Kyberd, P; Leslie, D; Munro, C; Reid, I D; Siamitros, C; Taylor, R; Teodorescu, L; Yaselli, I; Bose, T; Carleton, M; Hazen, E; Heering, A H; Heister, A; John, J St; Lawson, P; Lazic, D; Osborne, D; Rohlf, J; Sulak, L; Wu, S; Andrea, J; Avetisyan, A; Bhattacharya, S; Chou, J P; Cutts, D; Esen, S; Kukartsev, G; Landsberg, G; Narain, M; Nguyen, D; Speer, T; Tsang, K V; Breedon, R; Calderon De La Barca Sanchez, M; Case, M; Cebra, D; Chertok, M; Conway, J; Cox, P T; Dolen, J; Erbacher, R; Friis, E; Ko, W; Kopecky, A; Lander, R; Lister, A; Liu, H; Maruyama, S; Miceli, T; Nikolic, M; Pellett, D; Robles, J; Searle, M; Smith, J; Squires, M; Stilley, J; Tripathi, M; Vasquez Sierra, R; Veelken, C; Andreev, V; Arisaka, K; Cline, D; Cousins, R; Erhan, S; Hauser, J; Ignatenko, M; Jarvis, C; Mumford, J; Plager, C; Rakness, G; Schlein, P; Tucker, J; Valuev, V; Wallny, R; Yang, X; Babb, J; Bose, M; Chandra, A; Clare, R; Ellison, J A; Gary, J W; Hanson, G; Jeng, G Y; Kao, S C; Liu, F; Liu, H; Luthra, A; Nguyen, H; Pasztor, G; Satpathy, A; Shen, B C; Stringer, R; Sturdy, J; Sytnik, V; Wilken, R; Wimpenny, S; Branson, J G; Dusinberre, E; Evans, D; Golf, F; Kelley, R; Lebourgeois, M; Letts, J; Lipeles, E; Mangano, B; Muelmenstaedt, J; Norman, M; Padhi, S; Petrucci, A; Pi, H; Pieri, M; Ranieri, R; Sani, M; Sharma, V; Simon, S; Würthwein, F; Yagil, A; Campagnari, C; D'Alfonso, M; Danielson, T; Garberson, J; Incandela, J; Justus, C; Kalavase, P; Koay, S A; Kovalskyi, D; Krutelyov, V; Lamb, J; Lowette, S; Pavlunin, V; Rebassoo, F; Ribnik, J; Richman, J; Rossin, R; Stuart, D; To, W; Vlimant, J R; Witherell, M; Apresyan, A; Bornheim, A; Bunn, J; Chiorboli, M; Gataullin, M; Kcira, D; Litvine, V; Ma, Y; Newman, H B; Rogan, C; Timciuc, V; Veverka, J; Wilkinson, R; Yang, Y; Zhang, L; Zhu, K; Zhu, R Y; Akgun, B; Carroll, R; Ferguson, T; Jang, D W; Jun, S Y; Paulini, M; Russ, J; Terentyev, N; Vogel, H; Vorobiev, I; Cumalat, J P; Dinardo, M E; Drell, B R; Ford, W T; Heyburn, B; Luiggi Lopez, E; Nauenberg, U; Stenson, K; Ulmer, K; Wagner, S R; Zang, S L; Agostino, L; Alexander, J; Blekman, F; Cassel, D; Chatterjee, A; Das, S; Gibbons, L K; Heltsley, B; Hopkins, W; Khukhunaishvili, A; Kreis, B; Kuznetsov, V; Patterson, J R; Puigh, D; Ryd, A; Shi, X; Stroiney, S; Sun, W; Teo, W D; Thom, J; Vaughan, J; Weng, Y; Wittich, P; Beetz, C P; Cirino, G; Sanzeni, C; Winn, D; Abdullin, S; Afaq, M A; Albrow, M; Ananthan, B; Apollinari, G; Atac, M; Badgett, W; Bagby, L; Bakken, J A; Baldin, B; Banerjee, S; Banicz, K; Bauerdick, L A T; Beretvas, A; Berryhill, J; Bhat, P C; Biery, K; Binkley, M; Bloch, I; Borcherding, F; Brett, A M; Burkett, K; Butler, J N; Chetluru, V; Cheung, H W K; Chlebana, F; Churin, I; Cihangir, S; Crawford, M; Dagenhart, W; Demarteau, M; Derylo, G; Dykstra, D; Eartly, D P; Elias, J E; Elvira, V D; Evans, D; Feng, L; Fischler, M; Fisk, I; Foulkes, S; Freeman, J; Gartung, P; Gottschalk, E; Grassi, T; Green, D; Guo, Y; Gutsche, O; Hahn, A; Hanlon, J; Harris, R M; Holzman, B; Howell, J; Hufnagel, D; James, E; Jensen, H; Johnson, M; Jones, C D; Joshi, U; Juska, E; Kaiser, J; Klima, B; Kossiakov, S; Kousouris, K; Kwan, S; Lei, C M; Limon, P; Lopez Perez, J A; Los, S; Lueking, L; Lukhanin, G; Lusin, S; Lykken, J; Maeshima, K; Marraffino, J M; Mason, D; McBride, P; Miao, T; Mishra, K; Moccia, S; Mommsen, R; Mrenna, S; Muhammad, A S; Newman-Holmes, C; Noeding, C; O'Dell, V; Prokofyev, O; Rivera, R; Rivetta, C H; Ronzhin, A; Rossman, P; Ryu, S; Sekhri, V; Sexton-Kennedy, E; Sfiligoi, I; Sharma, S; Shaw, T M; Shpakov, D; Skup, E; Smith, R P; Soha, A; Spalding, W J; Spiegel, L; Suzuki, I; Tan, P; Tanenbaum, W; Tkaczyk, S; Trentadue, R; Uplegger, L; Vaandering, E W; Vidal, R; Whitmore, J; Wicklund, E; Wu, W; Yarba, J; Yumiceva, F; Yun, J C; Acosta, D; Avery, P; Barashko, V; Bourilkov, D; Chen, M; Di Giovanni, G P; Dobur, D; Drozdetskiy, A; Field, R D; Fu, Y; Furic, I K; Gartner, J; Holmes, D; Kim, B; Klimenko, S; Konigsberg, J; Korytov, A; Kotov, K; Kropivnitskaya, A; Kypreos, T; Madorsky, A; Matchev, K; Mitselmakher, G; Pakhotin, Y; Piedra Gomez, J; Prescott, C; Rapsevicius, V; Remington, R; Schmitt, M; Scurlock, B; Wang, D; Yelton, J; Ceron, C; Gaultney, V; Kramer, L; Lebolo, L M; Linn, S; Markowitz, P; Martinez, G; Rodriguez, J L; Adams, T; Askew, A; Baer, H; Bertoldi, M; Chen, J; Dharmaratna, W G D; Gleyzer, S V; Haas, J; Hagopian, S; Hagopian, V; Jenkins, M; Johnson, K F; Prettner, E; Prosper, H; Sekmen, S; Baarmand, M M; Guragain, S; Hohlmann, M; Kalakhety, H; Mermerkaya, H; Ralich, R; Vodopiyanov, I; Abelev, B; Adams, M R; Anghel, I M; Apanasevich, L; Bazterra, V E; Betts, R R; Callner, J; Castro, M A; Cavanaugh, R; Dragoiu, C; Garcia-Solis, E J; Gerber, C E; Hofman, D J; Khalatian, S; Mironov, C; Shabalina, E; Smoron, A; Varelas, N; Akgun, U; Albayrak, E A; Ayan, A S; Bilki, B; Briggs, R; Cankocak, K; Chung, K; Clarida, W; Debbins, P; Duru, F; Ingram, F D; Lae, C K; McCliment, E; Merlo, J P; Mestvirishvili, A; Miller, M J; Moeller, A; Nachtman, J; Newsom, C R; Norbeck, E; Olson, J; Onel, Y; Ozok, F; Parsons, J; Schmidt, I; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Chien, C Y; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Zhang, Y; Baringer, P; Bean, A; Grachov, O; Murray, M; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Kaadze, K; Liu, A; Maravin, Y; Onoprienko, D; Svintradze, I; Wan, Z; Gronberg, J; Hollar, J; Lange, D; Wright, D; Baden, D; Bard, R; Boutemeur, M; Eno, S C; Ferencek, D; Hadley, N J; Kellogg, R G; Kirn, M; Kunori, S; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Toole, T; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns.

  7. The Interrelationship between Marine Biofouling and Cathodic Protection

    Science.gov (United States)

    1993-01-01

    imposing a cathodic potential on the surface by means of an impressed direct current, attachment to a sacrificial anode , or both. The cost of CP is...exposed in the cstuarine waters of Aberdeen Habor using an imposed potential of -1024 mV and sacrificial anodes . 15 Activities within biofilms were...all chemical reactions involving calcium , magnesium, and bicarbonate ions: HCO 3- + OH- -+ H20 + CO3 (3) Ca+2 + C0 3 m --- CaCO3 (4) Mg+2 + 20H- --N

  8. Large-scale cathodic carboxylation of copper surfaces

    OpenAIRE

    Simonet, Jacques

    2017-01-01

    International audience; Large scale carboxylation of copper can easily be achieved by redn. of CO2 solubilised in aprotic polar solvents in the presence of tetramethylammonium salts (TMeA+ X-). Carbon dioxide could be inserted into the metal matrix (presumably in the form of the carbon dioxide anion radical) at high surface concns. (up to 10- 7 mol cm- 2), most probably organized in multi-layers. With significant amts. of electricity (> 0.1 × 10- 2 C cm- 2), this cathodic procedure leads to a...

  9. Advanced Nanofiber-Based Lithium-Ion Battery Cathodes

    Science.gov (United States)

    Toprakci, Ozan

    Among various energy storage technologies, rechargeable lithium-ion batteries have been considered as effective solution to the increasing need for high-energy density electrochemical power sources. Rechargeable lithium-ion batteries offer energy densities 2 - 3 times and power densities 5 - 6 times higher than conventional Ni-Cd and Ni-MH batteries, and as a result, they weigh less and take less space for a given energy delivery. However, the use of lithium-ion batteries in many large applications such as electric vehicles and storage devices for future power grids is hindered by the poor thermal stability, relatively high toxicity, and high cost of lithium cobalt oxide (LiCoO2) powders, which are currently used as the cathode material in commercial lithium-ion batteries. Recently, lithium iron phosphate (LiFePO 4) powders have become a favorable cathode material for lithium-ion batteries because of their low cost, high discharge potential (around 3.4 V versus Li/Li+), large specific capacity (170 mAh g -1), good thermal stability, and high abundance with the environmentally benign and safe nature. As a result, there is a huge demand for the production of high-performance LiFePO4. However, LiFePO4 also has its own limitation such as low conductivity (˜10-9 S cm -1), which results in poor rate capability. To address this problem, various approaches can be used such as decreasing particle size of LiFePO 4, doping LiFePO4 with metal ions or coating LiFePO 4 surface with carboneous materials. Formation of conductive layer on LiFePO4 and decreasing particle size are promising approaches due to their superior contribution to electrical conductivity and electrochemical performance of LiFePO4. Although different approaches can be used for surface coating and particle size decrement, electrospinning can be potentially considered as an efficient, simple and inexpensive way. In this study, LiFePO 4/carbon and carbon nanotube- and graphene-loaded electrospun LiFePO 4/carbon

  10. Effect of mulitivalent cation dopants on lithium manganese spinel cathodes

    CSIR Research Space (South Africa)

    De Kock, A

    1998-02-01

    Full Text Available Journal of Power Sources 70 (I 998) 247-252 The effect of multivalent cation dopants on lithium manganese spine1 cathodes A. de Kock, E. Ferg * , R.J. Gummow Dii,ision of Matericrls Scrence and Technoiog,v, CSIR. P.0. Bar ZY5... of multivalent cation dopants (Mg?+. Zn?+ and Al?+ ). Optimal dopant levelx to achieve maximum capacity and the greatest stability with repeated cycling have been determined. The effect of doping the oxygen-rich spine1 Li...

  11. Use of Both Anode and Cathode Reactions in Wastewater Treatment

    Science.gov (United States)

    Brillas, Enric; Sirés, Ignasi; Cabot, Pere LluíS.

    Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical (•OH) produced from anode and/or cathode reactions. H2O2 is generated from the two-electron reduction of O2 at reticulated vitreous carbon, graphite, carbon-felt, and O2-diffusion cathodes. The most usual method is electro-Fenton where Fe2 + added to the wastewater reacts with electrogenerated H2O2 to yield •OH and Fe3 + from Fenton's reaction. An advantage of this technique is that Fe2 + is continuously regenerated from cathodic reduction of Fe3 +. The characteristics of different electro-Fenton systems where pollutants are simultaneously destroyed by •OH formed in the medium from Fenton's reaction and at the anode surface from water oxidation are explained. The effect of the anode [Pt or boron-doped diamond (BDD)] and cathode (carbon-felt or O2-diffusion) on the degradation rate of persistent industrial by-products, herbicides, pharmaceuticals, dyes, etc. is examined. Initial pollutants react much more rapidly with •OH formed in the medium and their degradation sequences are discussed from aromatic intermediates and finally short aliphatic acids are detected. The synergetic positive catalytic effect of Cu2 + on the electro-Fenton process is evidenced. The photoelectro-Fenton method involves the irradiation of the wastewater with UVA light that rapidly photodecomposes complexes of Fe3 + with final carboxylic acids enhancing total decontamination. The peroxicoagulation method uses a sacrificial Fe anode that is continuously oxidized to Fe2 + and organics are either mineralized

  12. Signal propagation in straw tubes with resistive cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Marzec, J.; Zaremba, K.; Pawlowski, Z.; Konarzewski, B.

    2000-02-01

    The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. They have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, their approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors.

  13. Nano-patterned superconducting surface for high quantum efficiency cathode

    Science.gov (United States)

    Hannon, Fay; Musumeci, Pietro

    2017-03-07

    A method for providing a superconducting surface on a laser-driven niobium cathode in order to increase the effective quantum efficiency. The enhanced surface increases the effective quantum efficiency by improving the laser absorption of the surface and enhancing the local electric field. The surface preparation method makes feasible the construction of superconducting radio frequency injectors with niobium as the photocathode. An array of nano-structures are provided on a flat surface of niobium. The nano-structures are dimensionally tailored to interact with a laser of specific wavelength to thereby increase the electron yield of the surface.

  14. Polarization spectroscopy of atomic erbium in a hollow cathode lamp

    Science.gov (United States)

    Ang’ong’a, Jackson; Gadway, Bryce

    2018-02-01

    In this work we perform polarization spectroscopy of erbium atoms in a hollow cathode lamp (HCL). We review the theory behind Doppler-free polarization spectroscopy, theoretically model the expected erbium polarization spectra, and compare the numerically calculated spectra to our experimental data. We further analyze the dependence of the measured spectra on the HCL current and the peak intensities of our pump and probe lasers to determine conditions. Applications include wavelength stabilization of diode laser radiation to the 400.91 nm erbium transition.

  15. High Capacity Cathode Materials for Next Generation Energy Storage

    Science.gov (United States)

    Papandrea, Benjamin John

    Energy storage devices are of increasing importance for applications in mobile electronics, hybrid electric vehicles, and can also play a critical role in renewable energy harvesting, conversion and storage. Since its commercial inception in the 1990's, the lithium-ion battery represents the dominant energy storage technology for mobile power supply today. However, the total capacity of lithium-ion batteries is largely limited by the theoretical capacities of the cathode materials such as LiCoO2 (272 mAh g-1), and LiFePO4 (170 mAh g-1), and cannot satisfy the increasing consumer demand, thus new cathode materials with higher capacities must be explored. Two of the most promising cathode materials with significantly larger theoretical capacities are sulfur (1675 mAh g-1) and air, specifically the oxygen (3840 mAh g-1). However, the usage of either of these cathodic materials is plagued with numerous issues that must be overcome before their commercialization. In the first part of my dissertation, we investigated the usage of a three-dimensional graphene membrane for a high energy density lithium-air (Li-Air) battery in ambient condition. One of the issues with Li-Air batteries is the many side reaction that can occur during discharge in ambient condition, especially with water vapor. Using a hydrophobic tortuous three-dimensional graphene membrane we are able to inhibit the diffusion of water vapor and create a lithium-air battery that cycles over 2000 times with a capacity limited at 140 mAh g-1, over 100 cycles with a capacity limited at 1425 mAh g-1, and over 20 cycles at the high capacity of 5700 mAh g-1. In the second part of my dissertation, we investigate the usage of a three-dimensional graphene aerogel to maximize the loading of sulfur to create a freestanding electrode with high capacity for a lithium-sulfur (Li-S) battery. We demonstrated that our three-dimensional graphene aerogel could sustain a loading of 95% by weight, and we achieved a capacity of

  16. Transient Performance Behavior of Proton Exchange Membrane Fuel Cell by Configuration of Membrane and Gas Diffusion Layer

    Science.gov (United States)

    Hwang, Sang Soon; Han, Sang Seok; Lee, Pil Hyong; Park, Bong Il

    A single-phase, fully three-dimensional transient numerical simulation was performed to analyze the dynamic response of a proton exchange membrane fuel cell (PEMFC) with single serpentine flow channels. . In addition, the effects of the membrane and gas diffusion layer thickness on current density transient behavior were investigated using numerical simulation. An overshoot of current density is observed for all thicknesses of the membrane and gas diffusion layer at an abrupt change of operating voltage from 0.7 V to 0.5 V. The peak of the overshoot and the elapsed thickness time to reach to the steady state value increase with decreasing membrane thickness. It is thought that the thin membrane facilitates the transport of water and ions through the membrane, resulting in an increase in current density and humidification of the membrane. The elapsed time to reach steady state voltage become shorter and the peak of the overshoot decreases as the thickness of the gas diffusion layer decreases. We suggest that this occurs because a thick gas diffusion layer increases the distance between the current collector (as heat exchanger) and catalyst layer (as heat source), resulting in a low transport rate of heat generated by the electrochemical reaction at the catalyst layer.

  17. Thermal Characteristics of Conversion-Type FeOF Cathode in Li-ion Batteries

    Directory of Open Access Journals (Sweden)

    Liwei Zhao

    2017-10-01

    Full Text Available Rutile FeOF was used as a conversion-type cathode material for Li-ion batteries. In the present study, 0.6Li, 1.4Li, and 2.7Li per mole lithiation reactions were carried out by changing the electrochemical discharge reaction depth. The thermal characteristics of the FeOF cathode were investigated by thermogravimetric mass spectrometric (TG-MS and differential scanning calorimeter (DSC systems. No remarkable HF release was detected, even up to 700 °C, which indicated a low toxic risk for the FeOF cathode. Changes in the thermal properties of the FeOF cathode via different conversion reaction depths in the associated electrolyte were studied by changing the cathode/electrolyte ratio in the mixture. LiFeOF was found to exothermically react with the electrolyte at about 210 °C. Similar exothermic reactions were found with charged FeOF cathodes because of the irreversible Li ions. Among the products of the conversion reaction of FeOF, Li2O was found to exothermically react with the electrolyte at about 120 °C, which induced the main thermal risk of the FeOF cathode. It suggests that the oxygen-containing conversion-type cathodes have a higher thermal risk than the oxygen-free ones, but controlling the cathode/electrolyte ratio in cells successfully reduced the thermal risk. Finally, the thermal stability of the FeOF cathode was evaluated in comparison with FeF3 and LiFePO4 cathodes.

  18. Landfill gas

    Energy Technology Data Exchange (ETDEWEB)

    Hartnell, Gaynor [Landfill Gas Association (United Kingdom)

    2000-07-01

    Following the UK Government's initiative for stimulating renewable energy through the Non-Fossil Fuel Obligation (NFFO), the UK landfill gas industry has more than trebled in size in just 4 years. As a result, UK companies are now in a strong position to offer their skills and services overseas. Ireland, Greece and Spain also resort heavily to disposal to landfill. Particularly rapid growth of the landfill gas market is expected in the OECD-Pacific and NAFTA areas. The article explains that landfill gas is a methane-rich mixture produced by anaerobic decomposition of organic wastes in landfills: under optimum conditions, up to 500 cubic meters of gas can be obtained from 1 tonne of biodegradable waste. Data on the number and capacity of sites in the UK are given. The Landfill Gas Association runs courses to counteract the skills shortage in the UK, and tailored courses for overseas visitors are planned.

  19. PIC-MCC analysis of electron multiplication in a cold-cathode Penning ion generator and its application to identify ignition voltage

    Science.gov (United States)

    Noori, H.; Ranjbar, A. H.; Mahjour-Shafiei, M.

    2017-11-01

    A cold-cathode Penning ion generator (PIG) has been developed in our laboratory to study the interaction of charged particles with matter. The ignition voltage was measured in the presence of the axial magnetic field in the range of 460-580 G. The performed measurements with stainless steel cathodes were in argon gas at pressure of 4 × 10-2 mbar. A PIC-MCC (particle-in-cell, Monte Carlo collision) technique has been used to calculate the electron multiplication coefficient M for various strength of axial magnetic field and applied voltage. An approach based on the coefficient M and the experimental values of the secondary electron emission coefficient γ, was proposed to determine the ignition voltages, theoretically. Applying the values of secondary coefficient γ leads to the average value of γM(V, B) to be = 1.05 ± 0.03 at the ignition of the PIG which satisfies the proposed ignition criterion. Thus, the ion-induced secondary electrons emitted from the cathode have dominant contribution to self-sustaining of the discharge process in a PIG.

  20. In-plane and through-plane non-uniform carbon corrosion of polymer electrolyte fuel cell cathode catalyst layer during extended potential cycles

    Science.gov (United States)

    Ghosh, Sourov; Ohashi, Hidenori; Tabata, Hiroshi; Hashimasa, Yoshiyuki; Yamaguchi, Takeo

    2017-09-01

    The impact of electrochemical carbon corrosion via potential cycling durability tests mimicking start-stop operation events on the microstructure of the cathode catalyst layer in polymer electrolyte fuel cells (PEFCs) is investigated using focused ion beam (FIB) fabrication without/with the pore-filling technique and subsequent scanning electron microscope (SEM) observations. FIB/SEM investigations without pore-filling reveals that the durability test induces non-uniform cathode shrinking across the in-plane direction; the thickness of the catalyst layer decreases more under the gas flow channel compared to the area under the rim of the flow field. Furthermore, FIB/SEM investigations with the pore-filling technique reveal that the durability test also induces non-uniform cathode shrinking in the through-plane direction; the pores in the area close to the membrane are more shrunken compared with those close to the microporous layer. In particular, a thin area (1-1.5 μm) close to the membrane is found to be severely damaged; it includes closed pores that hinder mass transport through the catalyst layer. It is suggested that uneven carbon corrosion and catalyst layer compaction are responsible for the performance loss during potential cycling operation of PEFCs.

  1. Use of novel permeable membrane and air cathodes in acetate microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Pant, Deepak, E-mail: deepak.pant@vito.b [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium); Van Bogaert, Gilbert; De Smet, Mark; Diels, Ludo; Vanbroekhoven, Karolien [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium)

    2010-11-01

    In the existing microbial fuel cells (MFCs), the use of platinized electrodes and Nafion as proton exchange membrane (PEM) leads to high costs leading to a burden for wastewater treatment. In the present study, two different novel electrode materials are reported which can replace conventional platinized electrodes and can be used as very efficient oxygen reducing cathodes. Further, a novel membrane which can be used as an ion permeable membrane (Zirfon) can replace Nafion as the membrane of choice in MFCs. The above mentioned gas porous electrodes were first tested in an electrochemical half cell configuration for their ability to reduce oxygen and later in a full MFC set up. It was observed that these non-platinized air electrodes perform very well in the presence of acetate under MFC conditions (pH 7, room temperature) for oxygen reduction. Current densities of -0.43 mA cm{sup -2} for a non-platinized graphite electrode and -0.6 mA cm{sup -2} for a non-platinized activated charcoal electrode at -200 mV vs. Ag/AgCl of applied potential were obtained. The proposed ion permeable membrane, Zirfonwas tested for its oxygen mass transfer coefficient, K{sub 0} which was compared with Nafion. The K{sub 0} for Zirfon was calculated as 1.9 x 10{sup -3} cm s{sup -1}.

  2. Tunable frequency-stabilization of UV laser using a Hallow-Cathode Lamp of atomic thallium

    CERN Document Server

    Chen, Tzu-Ling; Shy, Jow-Tsong; Liu, Yi-Wei

    2013-01-01

    A frequency-stabilized ultraviolet laser system, locked to the thallium resonant transition of 377.5 nm, was demonstrated using a novel bichromatic spectroscopy technique for tuning the zero-crossing laser-lock point. The atomic thallium system is a promising candidate in atomic parity violation and permanent electric dipole moment experiments, and its 377.5 nm 6P1/2->7S1/2 transition is important for thallium laser cooling and trapping experiment. The pressure shift, owing to the high pressure bu?er gas of the hollow-cathode lamp, was observed using an atomic beam resonance as reference. Such a shift was corrected by adjusting the peak ratio of the two Doppler-free saturation pro?les resulted from two pumping beams with a 130 MHz frequency di?erence. The resulted frequency stability of the ultraviolet laser is ?0.5 MHz at 0.1 sec integration time. This scheme is compact and versatile for stabilizing UV laser systems, which acquire a sub-MHz stability and frequency tunability.

  3. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton

    2012-09-01

    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  4. Metal foams application to enhance cooling of open cathode polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Sajid Hossain, Mohammad; Shabani, Bahman

    2015-11-01

    Conventional channel flow fields of open cathode Polymer Electrolyte Membrane Fuel Cells (PEMFCs) introduce some challenges linked to humidity, temperature, pressure and oxygen concentration gradients along the conventional flow fields that reduce the cell performance. According to previous experimental reports, with conventional air flow fields, hotspot formation due to water accumulation in Gas Diffusion Layer (GDL) is common. Unlike continuous long flow passages in conventional channels, metal foams provide randomly interrupted flow passages. Re-circulation of fluid, due to randomly distributed tortuous ligaments, enhances temperature and humidity uniformity in the fluid. Moreover, the higher electrical conductivity of metal foams compared to non-metal current collectors and their very low mass density compared to solid metal materials are expected to increase the electrical performance of the cell while significantly reducing its weight. This article reviews the existing cooling systems and identifies the important parameters on the basis of reported literature in the air cooling systems of PEMFCs. This is followed by investigating metal foams as a possible option to be used within the structure of such PEMFCs as an option that can potentially address cooling and flow distribution challenges associated with using conventional flow channels, especially in air-cooled PEMFCs.

  5. Experimental and ab initio investigations on textured Li–Mn–O spinel thin film cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J., E-mail: Julian.Fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Bergfeldt, T.; Ziebert, C.; Ulrich, S.; Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-01

    This paper describes the tailored preparation of nearly identical lithium–manganese–oxide thin film cathodes with different global grain orientations. The thin films were synthesized by rf magnetron sputtering from a LiMn{sub 2}O{sub 4}-target in a pure argon plasma. Under appropriate processing conditions, thin films with a cubic spinel structure and a nearly similar density and surface topography but different grain orientation, i.e. (111)- and (440)-textured films, were achieved. The chemical composition was determined by inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The constitution- and microstructure were evaluated by X-ray diffraction and Raman spectroscopy. The surface morphology and roughness were investigated by scanning electron and atomic force microscopy. The differently textured films represent an ideal model system for studying potential effects of grain orientation on the lithium ion diffusion and electrochemical behavior in LiMn{sub 2}O{sub 4}-based thin films. They are nearly identical in their chemical composition, atomic bonding behavior, surface-roughness, morphology and thickness. Our initial ab initio molecular dynamics data indicate that Li ion transport is faster in (111)-textured structure than in (440)-textured one. - Highlights: • Thin film model system of differently textured cubic Li–Mn–O spinels. • Investigation of the Li–Mn–O thin film mass density by X-ray reflectivity. • Ab initio molecular dynamics simulation on Li ion diffusion in LiMn{sub 2}O{sub 4}.

  6. Corrosion behavior of Cr/Ni alloy coated ferritic stainless steel in simulated cathodic PEMFC environments

    Energy Technology Data Exchange (ETDEWEB)

    Rendon, M.; Rivas, S.V.; Arriga, L.G.; Orozco, G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Queretaro (Mexico); Perez-Quiroz, J.T. [Inst. Mexicano del Transporte, Queretaro (Mexico); Porcayo, J. [Inst. de Investigaciones Electricas, Morelos (Mexico)

    2008-07-01

    The bipolar plate in a proton exchange membrane fuel cell (PEMFC) must be corrosion resistant and the interfacial contact resistance (ICR) with the gas diffusion layer must be low. For these reasons, stainless steel with high Cr content is considered to be a viable material for use in bipolar plate construction. This study evaluated the corrosion resistance of ferritic stainless steels 441 and 439, with and without a Cr/Ni coating, under simulated cathodic PEMFC conditions. Steel 441 without coating has a low corrosion current density and can be considered as a candidate material to be used as bipolar plate. The study showed that after the Cr/Ni coating was applied by Thermal Spray Metal method, the corrosion current density increased due to selective dissolution of an alloy element. The corrosion current density of the coatings was higher than the DOE target value, rendering them an unfeasible option to be used in bipolar plates for fuel cell applications. However, previous studies have shown that after the coating was applied, a passivation process improved the corrosion resistance. Although steel 441 appears to be a better candidate than steel 316 because of its lower cost, the behaviour of the Ni-Cr alloys was not satisfactory in corrosive acidic medium. 5 refs.

  7. Effect of Sulfate Acid on Electrolysis Process for Preparing EMD Using an Oxygen Depolarized Cathode

    Directory of Open Access Journals (Sweden)

    Hui ZHANG

    2014-04-01

    Full Text Available Electrolytic manganese dioxide (EMD was prepared by using gas diffusion electrode (GDE instead of traditional hydrogen evolution cathode. Sulfate acid’s effects on the cell voltage, the current efficiency, the electro-catalytic activity and the lifetime of GDE are studied. The results show that as the concentration of sulfuric acid increases, the current efficiency increases, while the cell voltage and the lifetime of GDE decreases. When the concentration of sulfuric acid is 20-40 g·dm- 3, the cell voltage is 1.1-1.2 V and the current efficiency is more than 99 %. When the concentration of sulfuric acid is 30 g·dm-3, the GDE has the best electro-catalytic activity, meanwhile the cell voltage maintains at 1.6 V after EMD is deposited on anode, and the lifetime of GDE reaches 400 h. XRD patterns show that all of the electrolytic products belong to g-MnO2 in different sulfuric acid concentration.

  8. Cathodic cage plasma deposition of TiN and TiO{sub 2} thin films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Romulo R. M. de [Department of Mechanics, Federal Institute of Education, Science, and Technology of Piaui, Praça da Liberdade, 1597, CEP 64000-040 Teresina, Piaui, Brazil and Department of Mechanical Engineering, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Sato, Patricia S.; Nascente, Pedro A. P., E-mail: nascente@ufscar.br [Department of Materials Engineering, Federal University of Sao Carlos, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, Sao Paulo (Brazil); Viana, Bartolomeu C. [Department of Physics, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Alves, Clodomiro [Department of Exact and Natural Sciences, Federal Rural University of Semi Arido, Avenida Francisco Mota, 572, CEP 59625-900 Mossoro, Rio Grande do Norte (Brazil); Nishimoto, Akio [Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2015-07-15

    Cathodic cage plasma deposition (CCPD) was used for growing titanium nitride (TiN) and titanium dioxide (TiO{sub 2}) thin films on silicon substrates. The main advantages of the CCPD technique are the uniformity, tridimensionality, and high rate of the film deposition that occurs at higher pressures, lower temperatures, and lower treatment times than those used in conventional nitriding treatments. In this work, the influence of the temperature and gas atmosphere upon the characteristics of the deposited films was investigated. The TiN and TiO{sub 2} thin films were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to analyze their chemical, structural, and morphological characteristics, and the combination of these results indicates that the low-cost CCPD technique can be used to produce even and highly crystalline TiN and TiO{sub 2} films.

  9. Effect of cathodic polarization on coating doxycycline on titanium surfaces.

    Science.gov (United States)

    Geißler, Sebastian; Tiainen, Hanna; Haugen, Håvard J

    2016-06-01

    Cathodic polarization has been reported to enhance the ability of titanium based implant materials to interact with biomolecules by forming titanium hydride at the outermost surface layer. Although this hydride layer has recently been suggested to allow the immobilization of the broad spectrum antibiotic doxycycline on titanium surfaces, the involvement of hydride in binding the biomolecule onto titanium remains poorly understood. To gain better understanding of the influence this immobilization process has on titanium surfaces, mirror-polished commercially pure titanium surfaces were cathodically polarized in the presence of doxycycline and the modified surfaces were thoroughly characterized using atomic force microscopy, electron microscopy, secondary ion mass spectrometry, and angle-resolved X-ray spectroscopy. We demonstrated that no hydride was created during the polarization process. Doxycycline was found to be attached to an oxide layer that was modified during the electrochemical process. A bacterial assay using bioluminescent Staphylococcus epidermidis Xen43 showed the ability of the coating to reduce bacterial colonization and planktonic bacterial growth. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Investigation of a Gallium MPD Thruster with an Ablating Cathode

    Science.gov (United States)

    Thomas, Robert E.; Burton, Rodney L.; Polzin, Kurt A.

    2010-01-01

    Arc impedance, exhaust velocity, and plasma probe measurements are presented. The thruster is driven by a 50 microsecond pulse from a 6.2 milliohm pulse forming network, and gallium is supplied to the discharge by evaporation of the cathode. The arc voltage is found to vary linearly with the discharge current with an arc impedance of 6.5 milliohms. Electrostatic probes yield an exhaust velocity that is invariant with the discharge current and has a peak value of 20 kilometers per second, which is in reasonable agreement with the value (16 plus or minus 1 kilometer per second) calculated from the mass bit and discharge current data. Triple probe measurements yield on axis electron temperatures in the range of 0.8-3.8 eV, electron densities in the range of 1.6 x 10(exp 21) to 2.1 x 10(exp 22) per cubic meter, and a divergence half angle of 16 degrees. Measurements within the interelectrode region yield a peak magnetic field of 0.8 T, and the observed radial trends are consistent with an azimuthally symmetric current distribution. A cathode power balance model is coupled with an ablative heat conduction model predicting mass bit values that are within 20% of the experimental values.

  11. Copper sulfates as cathode materials for Li batteries

    Science.gov (United States)

    Schwieger, Jonathan N.; Kraytsberg, Alexander; Ein-Eli, Yair

    As lithium battery technology sets out to bridge the gap between portable electronics and the electrical automotive industry, cathode materials still stand as the bottleneck regarding performances. In the realm of highly attractive polyanion-type structures as high-voltage cathode materials, the sulfate group (SO 4) 2- possesses an acknowledged superiority over other contenders in terms of open circuit voltage arising from the inductive effect of strong covalent S-O bonds. In parallel, novel lithium insertion mechanisms are providing alternatives to traditional intercalation, enabling reversible multi-electron processes securing high capacities. Combining both of these advantageous features, we report here the successful electrochemical reactivity of copper sulfate pentahydrate (CuSO 4·5H 2O) with respect to lithium insertion via a two-electron displacement reaction entailing the extrusion of metallic copper at a dual voltage of 3.2 V and 2.7 V followed by its reversible insertion at 3.5 V and 3.8 V. At this stage, cyclability was still shown to be limited due to the irreversible degradation to a monohydrate structure owing to constitutional water loss.

  12. Microbial fuel cell with an azo-dye-feeding cathode

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Liang [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Geochemistry; Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou (China). Guangdon Key Lab. of Agricultural Environment Pollution Integrated Control; Graduate Univ. of Chinese Academy of Sciences, Beijing (China); Li, Fang-bai [Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou (China). Guangdon Key Lab. of Agricultural Environment Pollution Integrated Control; Feng, Chun-hua [South China Univ. of Technology, Guangzhou (China). School of Chemistry and Chemical Engineering; Li, Xiang-zhong [Hong Kong Polytechnic Univ., Hong Kong (China). Dept. of Civil and Structural Engineering

    2009-11-15

    Microbial fuel cells (MFCs) were constructed using azo dyes as the cathode oxidants to accept the electrons produced from the respiration of Klebsiella pneumoniae strain L17 in the anode. Experimental results showed that a methyl orange (MO)-feeding MFC produced a comparable performance against that of an air-based one at pH 3.0 and that azo dyes including MO, Orange I, and Orange II could be successfully degraded in such cathodes. The reaction rate constant ({kappa}) of azo dye reduction was positively correlated with the power output which was highly dependent on the catholyte pH and the dye molecular structure. When pH was varied from 3.0 to 9.0, the k value in relation to MO degradation decreased from 0.298 to 0.016 {mu}mol min{sup -1}, and the maximum power density decreased from 34.77 to 1.51 mW m{sup -2}. The performances of the MFC fed with different azo dyes can be ranked from good to poor as MO > Orange I > Orange II. Furthermore, the cyclic voltammograms of azo dyes disclosed that the pH and the dye structure determined their redox potentials. A higher redox potential corresponded to a higher reaction rate. (orig.)

  13. Effect of cathodic polarization on coating doxycycline on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Geißler, Sebastian; Tiainen, Hanna; Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no

    2016-06-01

    Cathodic polarization has been reported to enhance the ability of titanium based implant materials to interact with biomolecules by forming titanium hydride at the outermost surface layer. Although this hydride layer has recently been suggested to allow the immobilization of the broad spectrum antibiotic doxycycline on titanium surfaces, the involvement of hydride in binding the biomolecule onto titanium remains poorly understood. To gain better understanding of the influence this immobilization process has on titanium surfaces, mirror-polished commercially pure titanium surfaces were cathodically polarized in the presence of doxycycline and the modified surfaces were thoroughly characterized using atomic force microscopy, electron microscopy, secondary ion mass spectrometry, and angle-resolved X-ray spectroscopy. We demonstrated that no hydride was created during the polarization process. Doxycycline was found to be attached to an oxide layer that was modified during the electrochemical process. A bacterial assay using bioluminescent Staphylococcus epidermidis Xen43 showed the ability of the coating to reduce bacterial colonization and planktonic bacterial growth. - Highlights: • Titanium hydride was found not to be involved in immobilization of doxycycline. • Doxycycline coating was strongly bound to a modified surface oxide layer. • Effect of coatings tested using a dynamic bacteria assay based on bioluminescence. • Topmost layer of adsorbed doxycycline was shown to have strong antibacterial effect.

  14. Methods for batch fabrication of cold cathode vacuum switch tubes

    Science.gov (United States)

    Walker, Charles A [Albuquerque, NM; Trowbridge, Frank R [Albuquerque, NM

    2011-05-10

    Methods are disclosed for batch fabrication of vacuum switch tubes that reduce manufacturing costs and improve tube to tube uniformity. The disclosed methods comprise creating a stacked assembly of layers containing a plurality of adjacently spaced switch tube sub-assemblies aligned and registered through common layers. The layers include trigger electrode layer, cathode layer including a metallic support/contact with graphite cathode inserts, trigger probe sub-assembly layer, ceramic (e.g. tube body) insulator layer, and metallic anode sub-assembly layer. Braze alloy layers are incorporated into the stacked assembly of layers, and can include active metal braze alloys or direct braze alloys, to eliminate costs associated with traditional metallization of the ceramic insulator layers. The entire stacked assembly is then heated to braze/join/bond the stack-up into a cohesive body, after which individual switch tubes are singulated by methods such as sawing. The inventive methods provide for simultaneously fabricating a plurality of devices as opposed to traditional methods that rely on skilled craftsman to essentially hand build individual devices.

  15. Copper sulfates as cathode materials for Li batteries

    Energy Technology Data Exchange (ETDEWEB)

    Schwieger, Jonathan N.; Kraytsberg, Alexander; Ein-Eli, Yair [Technion Israel Institute of Technology, Department of Materials Engineering, Technion City, Haifa 32000 (Israel)

    2011-02-01

    As lithium battery technology sets out to bridge the gap between portable electronics and the electrical automotive industry, cathode materials still stand as the bottleneck regarding performances. In the realm of highly attractive polyanion-type structures as high-voltage cathode materials, the sulfate group (SO{sub 4}){sup 2-} possesses an acknowledged superiority over other contenders in terms of open circuit voltage arising from the inductive effect of strong covalent S-O bonds. In parallel, novel lithium insertion mechanisms are providing alternatives to traditional intercalation, enabling reversible multi-electron processes securing high capacities. Combining both of these advantageous features, we report here the successful electrochemical reactivity of copper sulfate pentahydrate (CuSO{sub 4}.5H{sub 2}O) with respect to lithium insertion via a two-electron displacement reaction entailing the extrusion of metallic copper at a dual voltage of 3.2 V and 2.7 V followed by its reversible insertion at 3.5 V and 3.8 V. At this stage, cyclability was still shown to be limited due to the irreversible degradation to a monohydrate structure owing to constitutional water loss. (author)

  16. Monitoring Cathodic Shielding and Corrosion under Disbonded Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Varela, F.; Tan, M. Y. J.; Hinton, B.; Forsyth, M. [Deakin University, Victoria (Australia)

    2017-06-15

    Monitoring of corrosion is in most cases based on simulation of environmental conditions on a large and complex structure such as a buried pipeline using a small probe, and the measurement of thermodynamics and kinetics of corrosion processes occurring on the probe surface. This paper presents a hybrid corrosion monitoring probe designed for simulating deteriorating conditions wrought by disbonded coatings and for measuring current densities and distribution of such densities on a simulated pipeline surface. The concept of the probe was experimentally evaluated using immersion tests under cathodic protection (CP) in high resistivity aqueous solution. Underneath the disbonded area, anodic currents and cathodic currents were carefully measured. Anodic current densities were used to calculate metal loss according to Faraday’s law. Calculated corrosion patterns were compared with corrosion damage observed at the surface of the probe after a series of stringent tests. The capability of the probe to measure anodic current densities under CP, without requiring interruption, was demonstrated in high resistivity aqueous solution. The pattern of calculated metal loss correlated well with corrosion products distribution observed at the array surface. Working principles of the probe are explained in terms of electrochemistry.

  17. Evaluation of gasification and gas-cleanup processes for use in molten-carbonate fuel-cell power plants

    Science.gov (United States)

    1981-12-01

    A choice of the gasifier/cleanup system combinations most suitable for molten carbonate fuel cell based power plant application is discussed. Included are hot gas cleanup, air blown, oxygen blown and molten salt based coal gas supply systems. An assessment of deposition for power plant size molten carbonate fuel cells is given and mechanisms affecting particle transfer in fuel cells are described. Gas cleanup to remove virtually all particles larger than one micron in diameter is expected to prevent, or at least minimize to a negligibly low level, deposition of particulate material on the anode. However, cathode particulate deposition in molten carbonate fuel cells should be evaluated in the future, since cathodes are more likely to experience deposition even though cathode channel particle concentrations can be much lower than anode channel concentrations. Cathodes are more susceptible to deposition than anodes due to a net mass flow of gases into cathode pores compared to a net mass flow of gases out from anode pores.

  18. The Impact of Cathode Material and Shape on Current Density in an Aluminum Electrolysis Cell

    Science.gov (United States)

    Song, Yang; Peng, Jianping; Di, Yuezhong; Wang, Yaowu; Li, Baokuan; Feng, Naixiang

    2016-02-01

    A finite element model was developed to determine the impact of cathode material and shape on current density in an aluminum electrolysis cell. For the cathode material, results show that increased electrical resistivity leads to a higher cathode voltage drop; however, the horizontal current is reduced in the metal. The horizontal current magnitude for six different cathode materials in decreasing order is graphitized, semi-graphitized, full graphitic, 50% anthracite (50% artificial graphite), 70% anthracite (30% artificial graphite), 100% anthracite. The modified cathode shapes with an inclined cathode surface, higher collector bar and cylindrical protrusions are intended to improve horizontal current and flow resistance. Compared to a traditional cathode, modified collector bar sizes of 70 mm × 230 mm and 80 mm × 270 mm can reduce horizontal current density component Jx by 10% and 19%, respectively, due to better conductivity of the steel. The horizontal current in the metal decreases with increase of cathode inclination. The peak value of Jx can be approximately reduced by 20% for a 2° change in inclination. Cylindrical protrusions lead to local horizontal current increase on their tops, but the average current is less affected and the molten metal is effectively slowed down.

  19. Characterization of proton exchange membrane fuel cell cathode catalysts prepared by alcohol-reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, T.A.B.; Neto, A.O.; Chiba, R.; Seo, E.S.M., E-mail: tsantoro@ipen.br, E-mail: aolivei@ipen.br, E-mail: rchiba@ipen.br, E-mail: esmiyseo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Franco, E.G., E-mail: egberto@iee.usp.br [Universidade de Sao Paulo (IEE/USP), Sao Paulo, SP (Brazil). Instituto de Eletrotecnica e Energia

    2009-07-01

    Pt/rare-earth cathode catalysts were synthesized by the alcohol-reduction process and its structure was investigated by transmission electron microscopy (TEM), energy dispersive analyses (EDS), X-ray Diffraction (XRD). The electrochemical behavior of the cathode catalyst was analyzed by cyclic voltammetry (CV) chronoamperommetry (CA). (author)

  20. A pre-lithiation method for sulfur cathode used for future lithium metal free full battery

    Science.gov (United States)

    Wu, Yunwen; Yokoshima, Tokihiko; Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya

    2017-02-01

    Lithium metal free sulfur battery paired by lithium sulfide (Li2S) is a hot point in recent years because of its potential for relatively high capacity and its safety advantage. Due to the insulating nature and high sensitivity to moisture of Li2S, it calls for new way to introduce Li ion into S cathode besides the method of directly using the Li2S powder for the battery pre-lithiation. Herein, we proposed a pre-lithiation method to lithiate the polypyrrole (PPy)/S/Ketjenblack (KB) electrode into PPy/Li2S/KB cathode at room temperature. By this process, the fully lithiated PPy/Li2S/KB cathode showed facilitated charge transfer than the original PPy/S/KB cathode, leading to better cycling performance at high C-rates and disappearance of over potential phenomenon. In this work, the ion-selective PPy layer has been introduced on the cathode surface by an electrodeposition method, which can suppress the polysulfide dissolution from the cathode source. The lithium metal free full battery coupled by the prepared Li2S/KB cathode and graphite anode exhibited excellent cycling performance. Hence, we believe this comprehensive fabrication approach of Li2S cathode will pave a way for the application of new type lithium metal free secondary battery.