WorldWideScience

Sample records for hollow anode glow

  1. Self-pulsing in a low-current hollow cathode discharge: From Townsend to glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yu [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xie, Kan, E-mail: xiekan@bit.edu.cn [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yu; Ouyang, Jiting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

    2016-02-15

    We investigate the self-pulsing phenomenon of a low current cavity discharge in a cylindrical hollow cathode in pure argon. The waveforms of pulsed current and voltage are measured, and the time-averaged and time-resolved images of hollow cathode discharge are recorded by using high-speed intensified charge coupled device camera. The results show that the self-pulsing is a mode transition between low-current stage of Townsend discharge and high-current stage of glow discharge. During the self-pulsing, the current rising time relates to the dissipation of space charges, and the decay time relates to the reconstruction of the virtual anode by the accumulation of positive ions. Whether or not space charges can form and keep the virtual anode is responsible for the discharge mode and hence plays an important role in the self-pulsing phenomenon in low current hollow cathode discharge.

  2. Anodization of aluminum and silicon in plasma of a non-self-sustained glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Burachevsky, Yu. A., E-mail: office@tusur.ru; Burdovitsin, V. A.; Oks, E. M. [Tomsk State University of Control Systems and Radioelectronics (Russian Federation)

    2011-12-15

    The results of anodization of aluminum and silicon in an oxygen plasma are presented. The plasma was generated by a non-self-sustained glow discharge with a hollow cathode excited by an electron beam at the oxygen pressure of 20 Pa. The density of the current flowing through the anodized specimen did not exceed 1.5 mA/cm{sup 2}, and its temperature was 200-250 Degree-Sign C. Continuous Al{sub 2}O{sub 3} and SiO{sub 2} films were formed on the aluminum and silicon surfaces. The growth rate of the oxide layers was 150-200 nm/h for Al{sub 2}O{sub 3} and 400-800 nm/h for SiO{sub 2}.

  3. Mineralization of aqueous pentachlorophenolate by anodic contact glow discharge electrolysis

    Institute of Scientific and Technical Information of China (English)

    Haiming Yang; Meguru Tezuka

    2011-01-01

    Exhaustive mineralization of pentachlorophenolate ion (PCP) in phosphate buffer was carried out using anodic contact glow discharge electrolysis (CGDE), in which plasma was sustained between the electrolyte and anode. During CGDE, PCP degraded smoothly. The amount of total organic carbon decreased significantly, indicating the eventual conversion of the carbon atoms of benzene nucleus to inorganic carbons. Furthermore, chlorine atoms in PCP were liberated as chloride ions. As a primary intermediate product, 2,3,5,6-tetrachloro-1,4-benzoquinone was detected, and oxalate and formate as byproducts were also found. It was revealed that disappearance of PCP obeyed first-order kinetics. The reaction rate was generally unaffected by both O2 and inert gases in the cell, although it decreased by raising initial pH of solution. In addition, a plausible reaction pathway involving hydroxyl radical was proposed.

  4. Modelling of local ion nitriding in a glow discharge with hollow cathode

    Science.gov (United States)

    Budilov, V.; Ramazanov, K.; Khusainov, Yu

    2017-05-01

    The paper presents the results of computer calculations of glow discharge plasma parameters in a hollow cathode zone and modeling of thermal and diffusion processes at local ion nitriding with a hollow cathode. The proposed model of a glow discharge with a hollow cathode with sufficient accuracy allowed to describe the distribution of plasma parameters in a cathode void. Values of plasma parameters in a cathode void formed by a mesh screen and cathode surface were obtained via the probe method. It was found that the use of hollow cathode effect allows to increase the concentration of ions near the treated surface by 1.5 times. The suggested computer model allows to predict the distribution of the temperature field and depth of a diffusion layer at local ion nitriding with a hollow cathode for various configurations and sizes.

  5. Two-dimensional, hybrid model of glow discharge in hollow cathode geometries

    Energy Technology Data Exchange (ETDEWEB)

    Fiala, A.; Pitchford, L.C.; Boeuf, J.P. [Universite Paul Sabatier, Toulouse (France)

    1995-12-31

    Low pressure glow discharges in plane-plane geometries have been studied extensively over the years and most of their features are known from experiments and numerical simulation. If a plane cathode is replaced by a cathode with some hollow structure, then, for a certain range of conditions, the negative glows of opposite (adjacent) cathode walls overlap and the discharge behaviour dramatically changes. The voltage is lower at a constant current and the current is even several orders of magnitude higher for a given voltage than for the plane cathode. At the same time, the intensity of the light emission from the discharge considerably increases. This effect is called the hollow cathode effect. There are several physical phenomena which could be responsible for the big efficiency of the hollow cathode discharges. The recent investigations based on the Monte Carlo simulation of the electron kinetics have shown that the trapping of energetic electrons in the hollow cathode cavity can explain the order of magnitude of the hollow cathode effect. The configuration of the discharge tube presented in fig. 1 is used here to study the behaviour of glow discharges in a hollow cathode means of numerical simulation.

  6. Non-self-sustained discharge with hollow anode for plasma-based surface treatment

    Directory of Open Access Journals (Sweden)

    Misiruk Ivan O.

    2016-06-01

    Full Text Available The paper discusses plasma methods for surface modification using the non-self-sustained glow discharge with a hollow anode. This discharge is characterised by low voltage and high values of electron and ion currents. It can be easily excited in vacuum-arc installations that are widely used for coatings deposition. It is shown that such type of discharge may be effectively used for ion pumping, film deposition, ion etching, diffusion saturation of metallic materials, fusion and brazing of metals, and for combined application of above mentioned technologies in a single vacuum cycle.

  7. Hollow Nanostructured Anode Materials for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2010-01-01

    Full Text Available Abstract Hollow nanostructured anode materials lie at the heart of research relating to Li-ion batteries, which require high capacity, high rate capability, and high safety. The higher capacity and higher rate capability for hollow nanostructured anode materials than that for the bulk counterparts can be attributed to their higher surface area, shorter path length for Li+ transport, and more freedom for volume change, which can reduce the overpotential and allow better reaction kinetics at the electrode surface. In this article, we review recent research activities on hollow nanostructured anode materials for Li-ion batteries, including carbon materials, metals, metal oxides, and their hybrid materials. The major goal of this review is to highlight some recent progresses in using these hollow nanomaterials as anode materials to develop Li-ion batteries with high capacity, high rate capability, and excellent cycling stability.

  8. Uniqueness theorem for the non-local ionization source in glow discharge and hollow cathode

    CERN Document Server

    Gorin, Vladimir V

    2012-01-01

    The paper is devoted to the proof of the uniqueness theorem for solution of the equation for the non-local ionization source in a glow discharge and a hollow cathode in general 3D geometry. The theorem is applied to wide class of electric field configurations, and to the walls of discharge volume, which have a property of incomplete absorption of the electrons. Cathode is regarded as interior singular source, which is placed arbitrarily close to the wall. The existence of solution is considered also. During the proof of the theorem many of useful structure formulae are obtained. Elements of the proof structure, which have arisen, are found to have physical sense. It makes clear physical construction of non-local electron avalanche, which builds a source of ionization in glow discharge at low pressures. Last has decisive significance to understand the hollow cathode discharge configuration and the hollow cathode effect.

  9. Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge

    Science.gov (United States)

    Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger

    2008-09-01

    Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting. In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.

  10. Development of hollow anode penning ion source for laboratory application

    Science.gov (United States)

    Das, B. K.; Shyam, A.; Das, R.; Rao, A. D. P.

    2012-03-01

    The research work presented here focuses for the development of miniature penning type ion source. One hollow anode penning type ion source was developed in our laboratory. The size of the ion source is 38 mm diameter and 55 mm length. The ion source consists of two cathodes, a hollow anode and one piece of rare earth permanent magnet. The plasma was created in the plasma region between cathodes and the hollow anode. The J × B force in the region helps for efficient ionization of the gas even in the high vacuum region˜1×10 -5 Torr. The ions were extracted in the axial direction with help of the potential difference between the electrodes and the geometry of the extraction angle. The effect of the extraction electrode geometry for efficient extraction of the ions from the plasma region was examined. This ion source is a self extracted ion source. The self extracted phenomena reduce the cost and the size of the ion source. The extracted ion current was measured by a graphite probe. An ion current of more than 200 μA was observed at the probe placed 70 mm apart from the extraction electrode. In this paper, the structure of the ion source, effect of operating pressure, potential difference and the magnetic field on the extracted ion current is reported.

  11. Experimental measurements of the hollow cathode DC glow discharge parameters in Ar and He plasmas

    Science.gov (United States)

    Omrani, M.; Amrollahi, R.; Iraji, D.

    2016-12-01

    In this article, we focus on some of the fundamental parameters of SS316L hollow cathode glow discharge. Four SS316L samples are placed at different locations on the cathode surface and the current passed through them is measured in Ar and He glow discharge plasmas. The wall current densities of Ar and He are in the range of 8-25 µA cm-2 and 8-35 µA cm-2, respectively. Results also show that with decreasing working pressure, the ion flux and current density distribution on the wall surface becomes more uniform. The ion flux of the Ar and He is in the range of 1013 to 1014 ~\\text{ion} \\text{c}{{\\text{m}}-2} . Total energy losses of Ar and He are measured at the pressure range of 1.4-5.5  ×  10-2 torr and 3.2-7.1  ×  10-1, respectively. In both Ar and He, total energy losses decreased with increasing pressure. The secondary electron emission coefficients of Ar and He, which are evaluated for the hallow cathode configuration, are about 0.42 and 0.26, respectively, and are higher in comparison with the plate cathode configuration.

  12. Auxiliary glow discharge in the trigger unit of a hollow-cathode thyratron

    Energy Technology Data Exchange (ETDEWEB)

    Korolev, Yu. D.; Landl, N. V., E-mail: landl@lnp.hcei.tsc.ru; Geyman, V. G.; Frants, O. B.; Shemyakin, I. A.; Nekhoroshev, V. O. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation)

    2016-08-15

    Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500–600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current−voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

  13. Auxiliary glow discharge in the trigger unit of a hollow-cathode thyratron

    Science.gov (United States)

    Korolev, Yu. D.; Landl, N. V.; Geyman, V. G.; Frants, O. B.; Shemyakin, I. A.; Nekhoroshev, V. O.

    2016-08-01

    Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500-600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current-voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

  14. Gas-discharge sources with charged particle emission from the plasma of glow discharge with a hollow cathode

    CERN Document Server

    Semenov, A P

    2001-01-01

    One studied properties of a magnetron discharge with a cold hollow and uncooled rod cathodes. One demonstrated the dominant effect of thermoelectron emission of a rod cathode heated in a discharge on characteristics of discharge and on emission properties of a gas-discharge plasma and the possibility pf a smooth transition of glow discharge to diffusion mode of arc discharge combustion. Paper describes sources of ions and electrons with improved physical and generalized design and engineering parameters. One shows the promise of the electrode structure of a hollow cathode magnetron discharge to be used as a source, in particular, of the atomic hydrogen and of atom flow of a working rod cathode

  15. Destruction of 4-phenolsulfonic acid in water by anodic contact glow discharge electrolysis

    Institute of Scientific and Technical Information of China (English)

    Haiming Yang; Baigang An; Shaoyan Wang; Lixiang Li; Wenjie Jin; Lihua Li

    2013-01-01

    Destruction of 4-phenolsulfonic acid (4-PSA) in water was carried out using anodic contact glow discharge electrolysis.Accompanying the decay of 4-PSA,the amount of total organic carbon (TOC) in water correspondingly decreased,while the sulfonate group of 4-PSA was released as sulfate ion.Oxalate and formate were obtained as minor by-products.Additionally,phenol,1,4-hydroquinone,hydroxyquinol and 1,4-benzoquinone were detected as primary intermediates in the initial stages of decomposition of 4-PSA.A reaction pathway involving successive attacks of hydroxyl and hydrogen radicals was assumed on the basis of the observed products and kinetics.It was revealed that the decay of both 4-PSA and TOC obeyed a first-order rate law.The effects of different Fe ions and initial concentrations of 4-PSA on the degradation rate were investigated.It was found that the presence of Fe ions could increase the degradation rate of 4-PSA,while initial concentrations lower than 80 mmol/L had no significant effect on kinetic behaviour.The disappearance rate of 4-PSA was significantly affected by pH.

  16. 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.

  17. Hierarchical hollow spheres of Fe2O3 @polyaniline for lithium ion battery anodes.

    Science.gov (United States)

    Jeong, Jae-Min; Choi, Bong Gill; Lee, Soon Chang; Lee, Kyoung G; Chang, Sung-Jin; Han, Young-Kyu; Lee, Young Boo; Lee, Hyun Uk; Kwon, Soonjo; Lee, Gaehang; Lee, Chang-Soo; Huh, Yun Suk

    2013-11-20

    Hierarchical hollow spheres of Fe2 O3 @polyaniline are fabricated by template-free synthesis of iron oxides followed by a post in- and exterior construction. A combination of large surface area with porous structure, fast ion/electron transport, and mechanical integrity renders this material attractive as a lithium-ion anode, showing superior rate capability and cycling performance.

  18. Silicon-Encapsulated Hollow Carbon Nanofiber Networks as Binder-Free Anodes for Lithium Ion Battery

    Directory of Open Access Journals (Sweden)

    Ding Nan

    2014-01-01

    Full Text Available Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder-free anodes for Li-ion batteries (LIBs. In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high-performance LIBs.

  19. Interconnected Silicon Hollow Nanospheres for Lithium-Ion Battery Anodes with Long Cycle Life

    KAUST Repository

    Yao, Yan

    2011-07-13

    Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g-1 with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure. © 2011 American Chemical Society.

  20. Interconnected silicon hollow nanospheres for lithium-ion battery anodes with long cycle life.

    Science.gov (United States)

    Yao, Yan; McDowell, Matthew T; Ryu, Ill; Wu, Hui; Liu, Nian; Hu, Liangbing; Nix, William D; Cui, Yi

    2011-07-13

    Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g(-1) with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure.

  1. Seeding the m = 0 instability in dense plasma focus Z-pinches with a hollow anode

    CERN Document Server

    Liu, J X; McMahon, M; Tummel, K; Cooper, C; Higginson, D; Shaw, B; Povilus, A; Link, A; Schmidt, A

    2016-01-01

    The dense plasma focus (DPF) is a classic Z-pinch plasma device that has been studied for decades as a radiation source. The formation of the m = 0 plasma instability during the compression phase is linked to the generation of high-energy charged particle beams, which, when operated in deuterium, lead to beam-target fusion reactions and the generation of neutron yield. In this paper, we present a technique of seeding the m = 0 instability by employing a hollow in the anode. As the plasma sheath moves along the anode's hollow structure, a low density perturbation is formed and this creates a non-uniform plasma column which is highly unstable. Dynamics of the low density perturbation and preferential seeding of the m = 0 instability were studied in detail with fully kinetic plasma simulations performed in the Large Scale Plasma particle-in-cell code as well as with a simple snowplow model. The simulations showed that by employing an anode geometry with appropriate inner hollow radius, the neutron yield of the D...

  2. Hollow silica-copper-carbon anodes using copper metal-organic frameworks as skeletons

    Science.gov (United States)

    Sun, Zixu; Xin, Fengxia; Cao, Can; Zhao, Chongchong; Shen, Cai; Han, Wei-Qiang

    2015-12-01

    Hollow silica-copper-carbon (H-SCC) nanocomposites are first synthesized using copper metal-organic frameworks as skeletons to form Cu-MOF@SiO2 and then subjected to heat treatment. In the composites, the hollow structure and the void space from the collapse of the MOF skeleton can accommodate the huge volume change, buffer the mechanical stress caused by lithium ion insertion/extraction and maintain the structural integrity of the electrode and a long cycling stability. The ultrafine copper with a uniform size of around 5 nm and carbon with homogeneous distribution from the decomposition of the MOF skeleton can not only enhance the electrical conductivity of the composite and preserve the structural and interfacial stabilization, but also suppress the aggregation of silica nanoparticles and cushion the volume change. In consequence, the resulting material as an anode for lithium-ion batteries (LIBs) delivers a reversible capacity of 495 mA h g-1 after 400 cycles at a current density of 500 mA g-1. The synthetic method presented in this paper provides a facile and low-cost strategy for the large-scale production of hollow silica/copper/carbon nanocomposites as an anode in LIBs.Hollow silica-copper-carbon (H-SCC) nanocomposites are first synthesized using copper metal-organic frameworks as skeletons to form Cu-MOF@SiO2 and then subjected to heat treatment. In the composites, the hollow structure and the void space from the collapse of the MOF skeleton can accommodate the huge volume change, buffer the mechanical stress caused by lithium ion insertion/extraction and maintain the structural integrity of the electrode and a long cycling stability. The ultrafine copper with a uniform size of around 5 nm and carbon with homogeneous distribution from the decomposition of the MOF skeleton can not only enhance the electrical conductivity of the composite and preserve the structural and interfacial stabilization, but also suppress the aggregation of silica nanoparticles and

  3. Generation of Volatile Cadmium and Zinc Species Based on Solution Anode Glow Discharge Induced Plasma Electrochemical Processes.

    Science.gov (United States)

    Liu, Xing; Liu, Zhifu; Zhu, Zhenli; He, Dong; Yao, Siqi; Zheng, Hongtao; Hu, Shenghong

    2017-03-21

    In this study, a novel high efficiency vapor generation strategy was proposed on the basis of solution anode glow discharge for the determination of Cd and Zn by atomic fluorescence spectrometry. In this approach, a glow discharge microplasma was acted as a gaseous cathode to initiate the plasma electrochemical vapor generation of Cd and Zn. Cadmium/zinc ions could be converted into molecular species efficiently at the plasma-liquid interface from a supporting electrolyte (HCl, pH = 3.2). It was found that the overall efficiency of the plasma electrochemical vapor generation (PEVG) system was much higher than the conventional electrochemical hydride generation (EcHG) and HCl-KBH4 system. With no requirement for other reducing reagents, this new approach enabled us to detect Cd and Zn with detection limits as low as 0.003 μg L(-1) for Cd and 0.3 μg L(-1) for Zn. Good repeatability (relative standard deviation (RSD), n = 5) was 2.4% for Cd (0.1 μg L(-1)) and 1.7% for Zn (10 μg L(-1)) standard. The accuracy of the proposed method was successfully validated through analysis of cadmium in reference material of stream sediment (GBW07311), soil (GBW07401), rice (GBW10045), and zinc in a simulated water sample (GSB 07-1184-2000). Replacing a metal electrode with a plasma offers the advantage of eliminating potential interactions between the species in liquid and the electrode, which solves the issues associated with electrode encountered in conventional EcHG. The ability to initiate electrochemical vapor generation reactions at the plasma-liquid interface opens a new approach for chemical vapor generation based on interactions between plasma gas-phase electrons and solutions.

  4. Generation of uniform low-temperature plasma in a pulsed non-self-sustained glow discharge with a large-area hollow cathode

    Science.gov (United States)

    Akhmadeev, Yu. H.; Denisov, V. V.; Koval, N. N.; Kovalsky, S. S.; Lopatin, I. V.; Schanin, P. M.; Yakovlev, V. V.

    2017-01-01

    Generation of plasma in a pulsed non-self-sustained glow discharge with a hollow cathode with an area of ≥2 m2 at gas pressures of 0.4-1 Pa was studied experimentally. At an auxiliary arc-discharge current of 100 A and a main discharge voltage of 240 V, a pulse-periodic glow discharge with a current amplitude of 370 A, pulse duration of 340 μs, and repetition rate of 1 kHz was obtained. The possibility of creating a uniform gas-discharge plasma with a density of up to 1012 cm-3 and an electron temperature of 1 eV in a volume of >0.2 m3 was demonstrated. Such plasma can be efficiently used to treat material surfaces and generate pulsed ion beams with a current density of up to 15 mA/cm2.

  5. Novel co-extruded electrolyte-anode hollow fibres for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Droushiotis, Nicolas; Othman, Mohd Hafiz Dzarfan; Doraswami, Uttam; Wu, Zhentao; Kelsall, Geoff; Li, Kang [Department of Chemical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2009-09-15

    Novel CGO/NiO-CGO dual-layer hollow fibres (HFs) have been fabricated in a single-step co-extrusion and co-sintering process. LSCF-CGO cathodes layers were then deposited onto the dual-layer HFs to construct micro-tubular SOFCs. The NiO in the micro-tubular HF-SOFCs was reduced at 550 C using hydrogen gas to form Ni anodes. Scanning electron microscope images showed that the dual-layer HFs have porous anodes and dense electrolyte layers. Preliminary measurements with a HF-SOFC fed with H{sub 2} and atmospheric oxygen, produced maximum power densities of 420 W m{sup -2} and 800 W m{sup -2} at 450 C and 550 C, respectively. (author)

  6. Development of realtime monitoring technology for laser photoreaction product - Study on spectroscopy of rare earth elements by using diode laser and hollow cathode glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Chun [Kyungnam University, Masan (Korea); Lee, Gea Ho [Chungnam National University, Taejon (Korea); Lee, Yong Il [Changwon National University, Changwon (Korea); Kim, Hyo Jin [Dongduk Women' s University, Seoul (Korea); Huh, Yong Dck [Dankook University, Seoul (Korea)

    1998-05-01

    Currently, fast and precise analysis of rare earth and actinide elements are much concerned and required for the safe treatments and storage of nuclear wastes generated by nuclear power plants. However, current technology is still far from the requirements for accurate realtime monitoring and measurement of radioactive elements. This project is of development of new technology of realtime monitoring and analysis of rare earth elements by using glow discharge and diode laser spectroscopy, and the study of spectroscopic characteristics of rare earth elements in glow discharge plasma. And, saturated absorption spectroscopy of rare earth elements was investigated with diode lasers. A see-through hollow cathode glow discharge (st-HCGD) cell was developed for the purpose of a portable atomizer and and its characteristics were investigated. High resolution spectroscopy was achieved with diode laser assisted saturated absorption spectroscopy. it is considered for major improvement of radioactive isotope detection technology. We expect a portable high resolution spectrometry with a see-through HCGD atomizer and diode lasers in near future. (Author). 63 refs., 39 figs., 7 tabs.

  7. High-performance, anode-supported, microtubular SOFC prepared from single-step-fabricated, dual-layer hollow fibers

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Mohd Hafiz Dzarfan; Droushiotis, Nicolas; Wu, Zhentao; Kelsall, Geoff; Li, Kang [Department of Chemical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2011-06-03

    A high-performance, microtubular solid oxide fuel cell is developed using an improved electrolyte/anode dual-layer hollow fiber fabricated via a novel coextrusion and co-sintering technique. The technique allows control over the porosity of the anode, resulting in an increase in the power output to almost double what has been previously reported. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Hollow Porous VOx/C Nanoscrolls as High-Performance Anodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Jia, Bao-Rui; Qin, Ming-Li; Zhang, Zi-Li; Li, Shu-Mei; Zhang, De-Yin; Wu, Hao-Yang; Zhang, Lin; Lu, Xin; Qu, Xuan-Hui

    2016-10-05

    Novel hollow porous VOx/C nanoscrolls are synthesized by an annealing process with the VOx/octadecylamine (ODA) nanoscrolls as both vanadium and carbon sources. In the preparation, the VOx/ODA nanoscrolls are first achieved by a two-phase solvothermal method using ammonium metavanadat as the precursor. Upon subsequent heating, the intercalated amines between the vanadate layers in the VOx/ODA nanoscrolls decompose into gases, which escape from inside the nanoscrolls and leave sufficient pores in the walls. As the anodes of lithium-ion batteries (LIBs), such hollow porous VOx/C nanoscrolls possess exceedingly high capacity and rate capability (904 mAh g(-1) at 1 A g(-1)) and long cyclic stability (872 mAh g(-1) after 210 cycles at 1 A g(-1)). The good performance is derived from the unique structural features of the hollow hierarchical porous nanoscrolls with low crystallinity, which could significantly suppress irreversible Li(+) trapping as well as improve Li(+) diffusion kinetics. This universal method of annealing amine-intercalated oxide could be widely applied to the fabrication of a variety of porous electrode materials for high-performance LIBs and supercapacitors.

  9. Research of the Effects of Electron Focused Electric Field upon an Enhanced Glow Discharge Plasma Ion Implantation

    Institute of Scientific and Technical Information of China (English)

    LI Liu-he; WU Yong-qin; ZHANG Yan-hua; CAI Xun; CHU Paul K

    2004-01-01

    A new Enhanced Glow Discharge Plasma Ion Implantation methods are introduced, in which the plasma are produced by the self glow discharge excitated by high negative voltage bias. The electric field is designed to a electron focusing mode by using a small area hollow anode and a large area sample holder cathode. The pattern of equipotentials of the electric field are calculated through finite-element method. By using the special electron-focusing field, the self glow discharge are enhanced and provide denser ions to implanted into the substrate.

  10. Nb{sub 2}O{sub 5} hollow nanospheres as anode material for enhanced performance in lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sasidharan, Manickam [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Gunawardhana, Nanda [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki, E-mail: yoshio@cc.saga-u.ac.jp [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Nakashima, Kenichi, E-mail: nakashik@cc.saga-u.ac.jp [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

    2012-09-15

    Graphical abstract: Nb{sub 2}O{sub 5} hollow nanosphere constructed electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles and maintains structural integrity and excellent cycling stability. Highlights: ► Nb{sub 2}O{sub 5} hollow nanospheres synthesis was synthesized by soft-template. ► Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode material in Li-ion battery. ► Nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles. ► The electrode maintains the structural integrity and excellent cycling stability. ► Nanosized shell domain facilitates fast lithium intercalation/deintercalation. -- Abstract: Nb{sub 2}O{sub 5} hollow nanospheres of average diameter ca. ∼29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g{sup −1}. The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb{sub 2}O{sub 5} shell domain that facilitates fast lithium intercalation/deintercalation kinetics.

  11. A dual layer Ni/Ni-YSZ hollow fibre for micro-tubular SOFC anode support with a current collector

    Energy Technology Data Exchange (ETDEWEB)

    Kanawka, Krzysztof; Othman, Mohd Hafiz Dzarfan; Wu, Zhentao; Droushiotis, Nicolas; Kelsall, Geoff; Li, Kang [Department of Chemical Engineering and Chemical Technology, Imperial College London (United Kingdom)

    2011-01-15

    A co-extrusion technique was employed to fabricate a dual layer NiO/NiO-YSZ hollow fibre precursor which was then co-sintered at 1400C and reduced at 700C to form, respectively, a meshed porous inner Ni current collector and outer Ni-YSZ anode layers for SOFC applications. Achieved morphology consisted of short finger-like voids originating from the inner bore of the hollow fibre, and a sponge-like structure filling most of the Ni-YSZ anode layer, which is considered to be suitable macrostructure for anode SOFC system. The electrical conductivity of the meshed porous inner Ni layer was measured to be 77.5 x 10{sup 5} S m{sup -1}. This result is significantly higher than previous reported results on single layer Ni-YSZ hollow fibres, which besides performing a catalyst function for the oxidation reaction also act as a current collector. These results highlight the advantages of this dual-layer hollow fibre design especially in developing a new and highly efficient way in current collection for micro-tubular SOFC. (author)

  12. Process for thermal imaging scanning of a swaged heater for an anode subassembly of a hollow cathode assembly

    Science.gov (United States)

    Patterson, Michael J. (Inventor); Verhey, Timothy R. R. (Inventor); Soulas, George C. (Inventor)

    2004-01-01

    A process for thermal imaging scanning of a swaged heater of an anode subassembly of a hollow cathode assembly, comprising scanning a swaged heater with a thermal imaging radiometer to measure a temperature distribution of the heater; raising the current in a power supply to increase the temperature of the swaged heater; and measuring the swaged heater temperature using the radiometer, whereupon the temperature distribution along the length of the heater shall be less than plus or minus 5 degrees C.

  13. Silicon nanoparticles encapsulated in hollow graphitized carbon nanofibers for lithium ion battery anodes

    Science.gov (United States)

    Kong, Junhua; Yee, Wu Aik; Wei, Yuefan; Yang, Liping; Ang, Jia Ming; Phua, Si Lei; Wong, Siew Yee; Zhou, Rui; Dong, Yuliang; Li, Xu; Lu, Xuehong

    2013-03-01

    Silicon (Si) is a promising material for lithium ion battery (LIB) anodes due to its high specific capacity. To overcome its shortcomings such as insulation property and large volume change during the charge-discharge process, a novel hybrid system, Si nanoparticles encapsulated in hollow graphitized carbon nanofibers, is studied. First, electrospun polyacrylonitrile (PAN)-Si hybrid nanofibers were obtained using water as the collector. The loose nanofiber lumps suspended in water have large inter-fiber distance, allowing in situ coating of a thin layer of polydopamine (PDA), the source for graphitized carbon, uniformly throughout the system. The designed morphology and structure were then realized by etching and calcination, and the morphology and structure were subsequently verified by various analytical techniques. Electrochemical measurements show that the resulting hollow hybrid nanofibers (C-PDA-Si NFs) exhibit much better cycling stability and rate capacity than conventional C/Si nanofibers derived by electrospinning of PAN-Si followed by calcination. For instance, the capacity of C-PDA-Si NFs is as high as 72.6% of the theoretical capacity after 50 cycles, and a high capacity of 500 mA h g-1 can be delivered at a current density of 5 A g-1. The significantly improved electrochemical properties of C-PDA-Si NFs are due to the excellent electrical conductivity of the carbonized PDA (C-PDA) shell that compensates for the insulation property of Si, the high electrochemical activity of C-PDA, which has a layered structure and is N-doped, the hollow nature of the nanofibers and small size of Si nanoparticles that ensure smooth insertion-extraction of lithium ions and more complete alloying with them, as well as the buffering effect of the remaining PAN-derived carbon around the Si nanoparticles, which stabilizes the structure.Silicon (Si) is a promising material for lithium ion battery (LIB) anodes due to its high specific capacity. To overcome its shortcomings

  14. Mesoporous hollow nanospheres consisting of carbon coated silica nanoparticles for robust lithium-ion battery anodes

    Science.gov (United States)

    An, Weili; Fu, Jijiang; Su, Jianjun; Wang, Lei; Peng, Xiang; Wu, Kai; Chen, Qiuyun; Bi, Yajun; Gao, Biao; Zhang, Xuming

    2017-03-01

    SiO2 as lithium ion batteries (LIBs) anode has drawn considerable attentions because of its low cost, high theoretical specific capacity and low discharge potentials but been limited by its low conductivity and electrochemical kinetics, resulting in obvious capacity decay and poor rate performance. Herein, we developed a simple approach to synthesize mesoporous hollow nanosphere (MHSiO2@C) assembled by conformal carbon coating tiny silica nanoparticles through chemical polymerization of dopamine inside the shell of MHSiO2. The continuous carbon can conformally coat on the surface of all primary SiO2 nanoparticles in the shell, which not only enhances the conductivity but also improves the structural stability of the MHSiO2. Compared to raw MHSiO2 and non-conformal carbon coated MHSiO2, the MHSiO2@C demonstrate a high reversible capacity of 440.7 mA h g-1 at a current density of 0.5 A g-1 after 500 cycles and excellent rate performance due to synergetic effect of special structure of MHSiO2 and carbon conformal coating on each silica nanoparticle. Such a special structure will be a promising platform for LIBs. Significantly, this paper offers a direct evidence to prove the advantage of conformal carbon coating and provides consequentially guide in improving the energy storage performance of low-conductivity oxide based electrode materials.

  15. Growth of Hollow Transition Metal (Fe, Co, Ni) Oxide Nanoparticles on Graphene Sheets through Kirkendall Effect as Anodes for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Yu, Xianbo; Qu, Bin; Zhao, Yang; Li, Chunyan; Chen, Yujin; Sun, Chunwen; Gao, Peng; Zhu, Chunling

    2016-01-26

    A general strategy based on the nanoscale Kirkendall effect has been developed to grow hollow transition metal (Fe, Co or Ni) oxide nanoparticles on graphene sheets. When applied as lithium-ion battery anodes, these hollow transition metal oxide-based composites exhibit excellent electrochemical performance, with high reversible capacities and long-term stabilities at a high current density, superior to most transition metal oxides reported to date.

  16. Formation of ZnMn{sub 2}O{sub 4} ball-in-ball hollow microspheres as a high-performance anode for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Genqiang; Lou, Xiong Wen [TUM-CREATE Centre for Electromobility, Singapore (Singapore); School of Chemical and Biomedical Engineering, Nanyang Technological University (Singapore); Yu, Le; Wu, Hao Bin [School of Chemical and Biomedical Engineering, Nanyang Technological University (Singapore); Hoster, Harry E. [TUM-CREATE Centre for Electromobility, Singapore (Singapore)

    2012-09-04

    Novel ZnMn{sub 2}O{sub 4} ball-in-ball hollow microspheres are fabricated by a facile two-step method involving the solution synthesis of ZnMn-glycolate hollow microspheres and subsequent thermal annealing in air. When evaluated as an anode material for lithium-ion batteries, these ZnMn{sub 2}O{sub 4} ball-in-ball hollow microspheres show significantly enhanced electrochemical performance with high capacity, excellent cycling stability and good rate capability. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Hollow/porous nanostructures derived from nanoscale metal-organic frameworks towards high performance anodes for lithium-ion batteries

    Science.gov (United States)

    Hu, Lin; Chen, Qianwang

    2014-01-01

    Lithium-ion batteries (LIBs), owing to their high energy density, light weight, and long cycle life, have shown considerable promise for storage devices. The successful utilization of LIBs depends strongly on the preparation of nanomaterials with outstanding lithium storage properties. Recent progress has demonstrated that hollow/porous nanostructured oxides are very attractive candidates for LIBs anodes due to their high storage capacities. Here, we aim to provide an overview of nanoscale metal-organic frameworks (NMOFs)-templated synthesis of hollow/porous nanostructured oxides and their LIBs applications. By choosing some typical NMOFs as examples, we present a comprehensive summary of synthetic procedures for nanostructured oxides, such as binary, ternary and composite oxides. Hollow/porous structures are readily obtained due to volume loss and release of internally generated gas molecules during the calcination of NMOFs in air. Interestingly, the NMOFs-derived hollow/porous structures possess several special features: pores generated from gas molecules release will connect to each other, which are distinct from ``dead pores'' pore size often appears to be <10 nm; in terms of surface chemistry, the pore surface is hydrophobic. These structural features are believed to be the most critical factors that determine LIBs' performance. Indeed, it has been shown that these NMOFs-derived hollow/porous oxides exhibit excellent electrochemical performance as anode materials for LIBs, including high storage capacity, good cycle stability, and so on. For example, a high charge capacity of 1465 mA h g-1 at a rate of 300 mA g-1 was observed after 50 cycles for NMOFs-derived Co3O4 porous nanocages, which corresponds to 94.09% of the initial capacity (1557 mA h g-1), indicating excellent stability. The capacity of NMOFs-derived Co3O4 is higher than that of other Co3O4 nanostructures obtained by a conventional two-step route, including nanosheets (1450 mA h g-1 at 50 mA g-1

  18. Mesoporous Silicon Hollow Nanocubes Derived from Metal-Organic Framework Template for Advanced Lithium-Ion Battery Anode.

    Science.gov (United States)

    Yoon, Taeseung; Bok, Taesoo; Kim, Chulhyun; Na, Younghoon; Park, Soojin; Kim, Kwang S

    2017-05-23

    Controlling the morphology of nanostructured silicon is critical to improving the structural stability and electrochemical performance in lithium-ion batteries. The use of removable or sacrificial templates is an effective and easy route to synthesize hollow materials. Herein, we demonstrate the synthesis of mesoporous silicon hollow nanocubes (m-Si HCs) derived from a metal-organic framework (MOF) as an anode material with outstanding electrochemical properties. The m-Si HC architecture with the mesoporous external shell (∼15 nm) and internal void (∼60 nm) can effectively accommodate volume variations and relieve diffusion-induced stress/strain during repeated cycling. In addition, this cube architecture provides a high electrolyte contact area because of the exposed active site, which can promote the transportation of Li ions. The well-designed m-Si HC with carbon coating delivers a high reversible capacity of 1728 mAhg(-1) with an initial Coulombic efficiency of 80.1% after the first cycle and an excellent rate capability of >1050 mAhg(-1) even at a 15 C-rate. In particular, the m-Si HC anode effectively suppresses electrode swelling to ∼47% after 100 cycles and exhibits outstanding cycle stability of 850 mAhg(-1) after 800 cycles at a 1 C-rate. Moreover, a full cell (2.9 mAhcm(-2)) comprising a m-Si HC-graphite anode and LiCoO2 cathode exhibits remarkable cycle retention of 72% after 100 cycles at a 0.2 C-rate.

  19. One-pot hydrothermal synthesis of hollow Fe3O4 microspheres assembled with nanoparticles for lithium-ion battery anodes

    DEFF Research Database (Denmark)

    Liu, Yanguo; Wang, Xiaoliang; Ma, Wuming

    2016-01-01

    Hollow Fe3O4 microspheres assembled with nanoparticles were successfully synthesized without the addition of any templates or subsequent treatments. When used as the anode materials for lithium-ion battery (LIB), the products showed good lithium storage properties, demonstrating their promising...

  20. Copper Silicate Hydrate Hollow Spheres Constructed by Nanotubes Encapsulated in Reduced Graphene Oxide as Long-Life Lithium-Ion Battery Anode.

    Science.gov (United States)

    Wei, Xiujuan; Tang, Chunjuan; Wang, Xuanpeng; Zhou, Liang; Wei, Qiulong; Yan, Mengyu; Sheng, Jinzhi; Hu, Ping; Wang, Bolun; Mai, Liqiang

    2015-12-09

    Hierarchical copper silicate hydrate hollow spheres-reduced graphene oxide (RGO) composite is successfully fabricated by a facile hydrothermal method using silica as in situ sacrificing template. The electrochemical performance of the composite as lithium-ion battery anode was studied for the first time. Benefiting from the synergistic effect of the hierarchical hollow structure and conductive RGO matrix, the composite exhibits excellent long-life performance and rate capability. A capacity of 890 mAh/g is achieved after 200 cycles at 200 mA/g and a capacity of 429 mAh/g is retained after 800 cycles at 1000 mA/g. The results indicate that the strategy of combining hierarchical hollow structures with conductive RGO holds the potential in addressing the volume expansion issue of high capacity anode materials.

  1. Ni/Ni-YSZ current collector/anode dual layer hollow fibers for micro-tubular solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kanawka, K.; Othman, M.H.D.; Droushiotis, N.; Wu, Z.; Kelsall, G.; Li, K. [Department of Chemical Engineering and Chemical Technology, Imperial College London, London SW7 2AZ (United Kingdom)

    2011-10-15

    A co-extrusion technique was employed to fabricate a novel dual layer NiO/NiO-YSZ hollow fiber (HF) precursor which was then co-sintered at 1,400 C and reduced at 700 C to form, respectively, a meshed porous inner Ni current collector and outer Ni-YSZ anode layers for SOFC applications. The inner thin and highly porous ''mesh-like'' pure Ni layer of approximately 50 {mu}m in thickness functions as a current collector in micro-tubular solid oxide fuel cell (SOFC), aiming at highly efficient current collection with low fuel diffusion resistance, while the thicker outer Ni-YSZ layer of 260 {mu}m acts as an anode, providing also major mechanical strength to the dual-layer HF. Achieved morphology consisted of short finger-like voids originating from the inner lumen of the HF, and a sponge-like structure filling most of the Ni-YSZ anode layer, which is considered to be suitable macrostructure for anode SOFC system. The electrical conductivity of the meshed porous inner Ni layer is measured to be 77.5 x 10{sup 5} S m{sup -1}. This result is significantly higher than previous reported results on single layer Ni-YSZ HFs, which performs not only as a catalyst for the oxidation reaction, but also as a current collector. These results highlight the advantages of this novel dual-layer HF design as a new and highly efficient way of collecting current from the lumen of micro-tubular SOFC. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Design and initial results from a kilojoule level dense plasma focus with hollow anode and cylindrically symmetric gas puff

    Science.gov (United States)

    Ellsworth, J. L.; Falabella, S.; Tang, V.; Schmidt, A.; Guethlein, G.; Hawkins, S.; Rusnak, B.

    2014-01-01

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ˜6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 107 per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  3. Macro-mesoporous hollow carbon spheres as anodes for lithium-ion batteries with high rate capability and excellent cycling performance

    Science.gov (United States)

    Yue, Xinyang; Sun, Wang; Zhang, Jing; Wang, Fang; Yang, Yuxiang; Lu, Chengyi; Wang, Zhenhua; Rooney, David; Sun, Kening

    2016-11-01

    In this work, nanostructured macro-mesoporous hollow carbon spheres (MMHCSs) with high surface areas (396 m2 g-1) were synthesized as anode materials via a facile template-based method. A macroporous structure was created on the surfaces of the mesoporous hollow carbon spheres without destroying their spherical structure by etching in 20% HF. The unique nanostructure (imperfect hollow spheres) and the beneficial characteristics of amorphous carbon gave the MMHCSs a high reversible capacity of 530 mAh g-1 at 2.5 A g-1 over 1000 cycles. Remarkably, the MMHCSs retained an excellent rate capability of 180 mAh g-1 at 60 A g-1, which was superior to that of perfectly structured mesoporous hollow carbon spheres (without macropore (MHCSs)).

  4. Hollow-Cuboid Li3VO4/C as High-Performance Anodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Zhang, Changkun; Liu, Chaofeng; Nan, Xihui; Song, Huanqiao; Liu, Yaguang; Zhang, Cuiping; Cao, Guozhong

    2016-01-13

    Li3VO4 has been demonstrated to be a promising anode material for lithium-ion batteries with a low, safe voltage and large capacity. However, its poor electronic conductivity hinders its practical application particularly at a high rate. This work reports that Li3VO4 coated with carbon was synthesized by a one-pot, two-step method with F127 ((PEO)100-(PPO)65-(PEO)100) as both template and carbon source, yielding a microcuboid structure. The resulting Li3VO4/C cuboid shows a stable capacity of 415 mAh g(-1) at 0.5 C and excellent capacity stability at high rates (e.g., 92% capacity retention after 1000 cycles at 10 C = 4 A g(-1)). The lithiation/delithiation process of Li3VO4/C was studied by ex situ X-ray diffraction and Raman spectroscopy, which confirmed that Li3VO4/C underwent a reversible intercalation reaction during discharge/charge processes. The excellent electrochemical performance is attributed largely to the unique microhollow structure. The voids inside hollow structure can not only provide more space to accommodate volume change during discharge/charge processes but also allow the lithium ions insertion and extraction from both outside and inside the hollow structure with a much larger surface area or more reaction sites and shorten the lithium ions diffusion distance, which leads to smaller overpotential and faster reaction kinetics. Carbon derived from F127 through pyrolysis coats Li3VO4 conformably and thus offers good electrical conduction. The results in this work provide convincing evidence that the significant potential of hollow-cuboid Li3VO4/C for high-power batteries.

  5. Graphitic Carbon-Coated FeSe2 Hollow Nanosphere-Decorated Reduced Graphene Oxide Hybrid Nanofibers as an Efficient Anode Material for Sodium Ion Batteries

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jung-Kul; Kang, Yun Chan

    2016-04-01

    A novel one-dimensional nanohybrid comprised of conductive graphitic carbon (GC)-coated hollow FeSe2 nanospheres decorating reduced graphene oxide (rGO) nanofiber (hollow nanosphere FeSe2@GC-rGO) was designed as an efficient anode material for sodium ion batteries and synthesized by introducing the nanoscale Kirkendall effect into the electrospinning method. The electrospun nanofibers transformed into hollow nanosphere FeSe2@GC-rGO hybrid nanofibers through a Fe@GC-rGO intermediate. The discharge capacities of the bare FeSe2 nanofibers, nanorod FeSe2-rGO-amorphous carbon (AC) hybrid nanofibers, and hollow nanosphere FeSe2@GC-rGO hyrbid nanofibers at a current density of 1 A g-1 for the 150th cycle were 63, 302, and 412 mA h g-1, respectively, and their corresponding capacity retentions measured from the 2nd cycle were 11, 73, and 82%, respectively. The hollow nanosphere FeSe2@GC-rGO hybrid nanofibers delivered a high discharge capacity of 352 mA h g-1 even at an extremely high current density of 10 A g-1. The enhanced electrochemical properties of the hollow nanosphere FeSe2@GC-rGO composite nanofibers arose from the synergetic effects of the FeSe2 hollow morphology and highly conductive rGO matrix.

  6. Flowing Liquid Anode Atmospheric Pressure Glow Discharge as an Excitation Source for Optical Emission Spectrometry with the Improved Detectability of Ag, Cd, Hg, Pb, Tl, and Zn.

    Science.gov (United States)

    Greda, Krzysztof; Swiderski, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-09-06

    A novel atmospheric pressure glow discharge generated in contact with a flowing liquid anode (FLA-APGD) was developed as the efficient excitation source for the optical emission spectrometry (OES) detection. Differences in the appearance and the electrical characteristic of the FLA-APGD and a conventional system operated with a flowing liquid cathode (FLC-APGD) were studied in detail and discussed. Under the optimal operating conditions for the FLA-APGD, the emission from the analytes (Ag, Cd, Hg, Pb, Tl, and Zn) was from 20 to 120 times higher as compared to the FLC-APGD. Limits of detections (LODs) established with a novel FLA-APGD system were on average 20 times better than those obtained for the FLC-APGD. A further improvement of the LODs was achieved by reducing the background shift interferences and, as a result, the LODs for Ag, Cd, Hg, Pb, Tl, and Zn were 0.004, 0.040, 0.70, 1.7, 0.035, and 0.45 μg L(-1), respectively. The precision of the FLA-APGD-OES method was evaluated to be within 2-5% (as the relative standard deviation of the repeated measurements). The method found its application in the determination of the content of Ag, Cd, Hg, Pb, Tl, and Zn in a certified reference material (CRM) of Lobster hepatopancreas (TORT-2), four brass samples as well as mineral water and tea leaves samples spiked with the analytes. In the case of brass samples, a reference method, i.e., inductively coupled plasma optical emission spectrometry (ICP-OES) was used. A good agreement between the results obtained with FLA-APGD-OES and the certified values for the CRM TORT-2 as well as the reference values obtained with ICP-OES for the brass samples was revealed, indicating the good accuracy of the proposed method. The recoveries obtained for the spiked samples of mineral water and tea leaves were within the range of 97.5-102%.

  7. Metal-organic framework derived porous CuO/Cu2O composite hollow octahedrons as high performance anode materials for sodium ion batteries.

    Science.gov (United States)

    Zhang, Xiaojie; Qin, Wei; Li, Dongsheng; Yan, Dong; Hu, Bingwen; Sun, Zhuo; Pan, Likun

    2015-11-25

    Porous CuO/Cu2O composite hollow octahedrons were synthesized simply by annealing Cu-based metal-organic framework templates. When evaluated as anode materials for sodium ion batteries, they exhibit a high maximum reversible capacity of 415 mA h g(-1) after 50 cycles at 50 mA g(-1) with excellent cycling stability and good rate capability.

  8. Glow discharges with electrostatic confinement of fast electrons

    Science.gov (United States)

    Kolobov, V. I.; Metel, A. S.

    2015-06-01

    This review presents a unified treatment of glow discharges with electrostatic confinement of fast electrons. These discharges include hollow cathode discharges, wire and cage discharges, reflect discharges with brush and multirod cathodes, and discharges in crossed electric and magnetic fields. Fast electrons bouncing inside electrostatic traps provide efficient ionization of gas at very low gas pressures. The electrostatic trap effect (ETE) was first observed by Paschen in hollow cathode discharges almost a century ago. The key parameters that define fundamental characteristics of ETE discharges are the ionization length λN, the penetration range, Λ, and the diffusion length λ of the fast electrons, and two universal geometric parameters of the traps: effective width a and length L. Peculiarities of electron kinetics and ion collection mechanism explain experimental observations for different trap geometries. The ETE is observed only at Λ > a, when the penetration range of the γ-electrons emitted by the cathode exceeds the trap width. In the optimal pressure range, when λN > a, and Λ current, Uc tends to its upper limit W/eβγ, where β is the percentage of ions arriving at the cathode and W is the gas ionization cost. In the low-pressure range, Λ > L, Uc rises from hundreds to thousands of volts. The sign of the anode potential fall, Ua, depends on the anode surface Sa and its position. When Sa is large compared to a critical value S*, Ua is negative and small. At Sa value of Ua becomes positive and rises up to 0.5-1 kV with decreasing p ultimately causing discharge extinction. Scaling laws indicate common physics between vacuum discharges and atmospheric pressure micro-discharges. We discuss peculiarities of electron kinetics under different conditions using semi-analytical models. Recent experimental results and applications of glow discharges with electrostatic confinement of fast electrons are described.

  9. Size-controlled SnO₂ hollow spheres via a template free approach as anodes for lithium ion batteries.

    Science.gov (United States)

    Bhaskar, Akkisetty; Deepa, Melepurath; Rao, Tata Narasinga

    2014-09-21

    Tin oxide hollow spheres (SnO₂ HS) with high structural integrity were synthesized by using a one pot hydrothermal approach with organic moieties as structure controlling agents. By adjusting the proportion of acetylacetone (AcAc) in the precursor formulation, SnO₂ HS of 200 and 350 nm dimensions, with a uniform shell thickness of about 50 nm, were prepared. Using the optimized solution composition with a Sn precursor, heating duration dependent structural evolution of SnO₂ was performed at a fixed temperature of 160 °C, which revealed a transition from solid spheres (1 h) to aggregated spheres (4 h) to porous spheres (10 h) to optimized HS (13 h) and finally to broken enlarged HS (24 h). A heating temperature dependent study carried out with a constant heating span of 13 h showed a metamorphosis from spheres with solid cores (140 °C) to ones with hollow cores (160 °C), culminating with fragmented HS, expanded in dimensions (180 °C). A growth mechanism was proposed for the optimized SnO₂ HS (2.5 or 5.0 mL of AcAc, 160 °C, 13 h) and the performance of these HS as anodes for Li ions batteries was evaluated by electrochemical studies. The 200 nm SnO₂ HS demonstrated an initial lithium storage capacity of 1055 mA h g(-1) at a current density of 100 mA g(-1), and they retained a capacity of 540 mA h g(-1) after 50 charge-discharge cycles. The SnO₂ HS also showed excellent rate capability as the electrode exhibited a capacity of 422 mA h g(-1) even at a high current density of 2000 mA g(-1). The notable capacity of SnO₂ HS is a manifestation of the mono-disperse quality of the SnO₂ HS coupled with the high number of electrochemically addressable sites, afforded by the large surface area of the HS and the striking cyclability is also attributed to the unique structure of HS, which is resistant to degradation upon repeated ion insertion/extraction. The SnO₂ HS were also found to be luminescent, thus indicating their usefulness for not only energy

  10. New Nanoconfined Galvanic Replacement Synthesis of Hollow Sb@C Yolk-Shell Spheres Constituting a Stable Anode for High-Rate Li/Na-Ion Batteries.

    Science.gov (United States)

    Liu, Jun; Yu, Litao; Wu, Chao; Wen, Yuren; Yin, Kuibo; Chiang, Fu-Kuo; Hu, Renzong; Liu, Jiangwen; Sun, Litao; Gu, Lin; Maier, Joachim; Yu, Yan; Zhu, Min

    2017-02-16

    In the current research project, we have prepared a novel Sb@C nanosphere anode with biomimetic yolk-shell structure for Li/Na-ion batteries via a nanoconfined galvanic replacement route. The yolk-shell microstructure consists of Sb hollow yolk completely protected by a well-conductive carbon thin shell. The substantial void space in the these hollow Sb@C yolk-shell particles allows for the full volume expansion of inner Sb while maintaining the framework of the Sb@C anode and developing a stable SEI film on the outside carbon shell. As for Li-ion battery anode, they displayed a large specific capacity (634 mAh g(-1)), high rate capability (specific capabilities of 622, 557, 496, 439, and 384 mAh g(-1) at 100, 200, 500, 1000, and 2000 mA g(-1), respectively) and stable cycling performance (a specific capacity of 405 mAh g(-1) after long 300 cycles at 1000 mA g(-1)). As for Na-ion storage, these yolk-shell Sb@C particles also maintained a reversible capacity of approximate 280 mAh g(-1) at 1000 mA g(-1) after 200 cycles.

  11. Rational design of carbon network cross-linked Si-SiC hollow nanosphere as anode of lithium-ion batteries

    Science.gov (United States)

    Wen, Zhenhai; Lu, Ganhua; Cui, Shumao; Kim, Haejune; Ci, Suqin; Jiang, Junwei; Hurley, Patrick T.; Chen, Junhong

    2013-12-01

    This study aims to realize controllable synthesis of Si-based nanostructures from common and easily accessible silica nanoparticles and to study their component/structure-dependent electrochemical performance as an anode of lithium-ion batteries (LIBs). To this end, a controllable route based on deliberate design has been developed to prepare hollow Si-based nanospheres with tunable composition and crystal structure at the nanoscale. The synthesis process started with coating silica nanoparticles with a carbonaceous polymer with a controllable thickness followed by magnesiothermic reduction. An Si-SiC-C composite was finally produced with a unique hollow sphere structure featuring Si-SiC nanoparticles encapsulated by a cross-linked carbon film network. In addition to the scalability of the synthetic route, the resulting composite exhibits a number of advantageous properties, including excellent electrical conductivity, highly accessible surfaces, structural coherence, and a favorable structure for the formation of a stable solid-electrolyte interphase, which makes it attractive and promising for advanced anode materials of LIBs.This study aims to realize controllable synthesis of Si-based nanostructures from common and easily accessible silica nanoparticles and to study their component/structure-dependent electrochemical performance as an anode of lithium-ion batteries (LIBs). To this end, a controllable route based on deliberate design has been developed to prepare hollow Si-based nanospheres with tunable composition and crystal structure at the nanoscale. The synthesis process started with coating silica nanoparticles with a carbonaceous polymer with a controllable thickness followed by magnesiothermic reduction. An Si-SiC-C composite was finally produced with a unique hollow sphere structure featuring Si-SiC nanoparticles encapsulated by a cross-linked carbon film network. In addition to the scalability of the synthetic route, the resulting composite exhibits a

  12. Carbon-covered Fe3O4 hollow cubic hierarchical porous composite as the anode material for lithium-ion batteries

    Science.gov (United States)

    Chen, Shouhui; Zhou, Rihui; Chen, Yaqin; Fu, Yuanyuan; Li, Ping; Song, Yonghai; Wang, Li

    2017-04-01

    In this work, Prussian blue nanocrystals, a kind of cubic metal-organic frameworks, was firstly covered by a uniform layer of resorcinol-formaldehyde (RF) resin, and then followed with heat treatment at different pyrolysis temperatures. The effects of pyrolysis temperature on the morphologies, phase, pore size, and electrochemical performance of the pyrolysis products were studied in this work. The composite generated at 600 ∘C, FexC600, was a hollow cubic composite of Fe3O4 covered by a thin RF-derived carbon layer. The carbon layer on FexC600 was a robust and conductive protective layer, which can accommodate Fe3O4 NPs and withstand the huge volume change of Fe3O4 during the process of discharge and charge. When used as anodes for lithium-ion batteries, FexC600 showed excellent electrochemical performance. It delivered a discharge capacity of 1126 mAh g-1 with a coulombic efficiency of 98.8% at the current density of 100 mA g-1 after 100 times discharge/charge cycling. It even delivered a capacity of 492 mAh g-1 at the current density of 500 mA g-1. This cubic hollow composite would be a promising alternative anode material for lithium-ion batteries.

  13. Fe3O4/C composite with hollow spheres in porous 3D-nanostructure as anode material for the lithium-ion batteries

    Science.gov (United States)

    Yang, Zhao; Su, Danyang; Yang, Jinping; Wang, Jing

    2017-09-01

    3d transition-metal oxides, especially Fe3O4, as anode materials for the lithium-ion batteries have been attracting intensive attentions in recent years due to their high energy capacity and low toxicity. A new Fe3O4/C composite with hollow spheres in porous three-dimensional (3D) nanostructure, which was synthesized by a facile solvothermal method using FeCl3·6H2O and porous spongy carbon as raw materials. The specific surface area and microstructures of composite were characterized by nitrogen adsorption-desorption isotherm method, FE-SEM and HR-TEM. A homogeneous distribution of hollow Fe3O4 spheres (diameter ranges from 120 nm to 150 nm) in the spongy carbon (pore size > 200 nm) conductive 3D-network significantly reduced the lithium-ion diffusion length and increased the electrochemical reaction area, and further more enhanced the lithium ion battery performance, such as discharge capacity and cycle life. As an anode material for the lithium-ion battery, the title composite exhibit excellent electrochemical properties. The Fe3O4/C composite electrode achieved a relatively high reversible specific capacity of 1450.1 mA h g-1 in the first cycle at 100 mA g-1, and excellent rate capability (69% retention at 1000 mA g-1) with good cycle stability (only 10% loss after 100 cycles).

  14. Effects of calcination temperature for rate capability of triple-shelled ZnFe2O4 hollow microspheres for lithium ion battery anodes

    Science.gov (United States)

    Hwang, Hojin; Shin, Haeun; Lee, Wan-Jin

    2017-04-01

    Triple-shelled ZnFe2O4 hollow microspheres (ZFO) as anode materials for lithium ion battery are prepared through a one-pot hydrothermal reaction using the composite solution consisting of sucrose in water and metal ions in ethylene glycol (EG), followed by different calcination processes. The architectures of ZFO micro spheres are differently synthesized through a mutual cooperation of inward and outward ripening with three different calcination temperatures. Thin triple-shelled ZnFe2O4 hollow microspheres calcined at 450 °C (ZFO-450) delivers a high reversible capacity of 932 mA h g-1 at a current density of 2 A g-1 even at the 200th cycle without obvious decay. Furthermore, ZFO-450 delivers 1235, 1005, 865, 834, and 845 mA h g-1 at high current densities of 0.5, 2, 5, 10, and 20 A g-1 after 100 cycles. Thin triple-shelled hollow microsphere prepared at an optimum calcination temperature provides exceptional rate capability and outstanding rate retention due to (i) the formation of nanoparticles leading to thin shell with morphological integrity, (ii) the facile mass transfer by thin shell with mesoporous structure, and (iii) the void space with macroporous structure alleviating volume change occurring during cycling.

  15. Design and synthesis of hollow NiCo2O4 nanoboxes as anodes for lithium-ion and sodium-ion batteries.

    Science.gov (United States)

    Chen, Junfen; Ru, Qiang; Mo, Yudi; Hu, Shejun; Hou, Xianhua

    2016-07-28

    Hollow porous NiCo2O4-nanoboxes (NCO-NBs) were synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the template followed by a subsequent annealing treatment. The structure and morphology of the NCO-NBs were characterized using X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. When tested as potential anode materials for lithium-ion batteries, these porous NCO-NBs with a well-defined hollow structure manifested enhanced performance of Li storage. The discharge capacity of the NCO-NBs remained 1080 mA h g(-1) after 150 cycles at a current rate of 500 mA g(-1) and 884 mA h g(-1) could be obtained at a current density of 2000 mA g(-1) after 200 cycles. Even when cycled at a high density of 8000 mA g(-1), a comparable capacity of 630 mA h g(-1) could be achieved. Meanwhile, the Na storage behavior of NCO-NBs as anode materials of sodium ion batteries (SIBs) was initially investigated and they exhibited a high initial discharge capacity of 826 mA h g(-1), and a moderate capacity retention of 328 mA h g(-1) was retained after 30 cycles. The improved electrochemical performance for NCO-NBs could be attributed to the hierarchical hollow structure and the desirable composition, which provide enough space to alleviate volume expansion during the Li(+)/Na(+) insertion/extraction process and facilitate rapid transport of ions and electrons.

  16. Unique Urchin-like Ca2Ge7O16 Hierarchical Hollow Microspheres as Anode Material for the Lithium Ion Battery.

    Science.gov (United States)

    Li, Dan; Feng, Chuanqi; Liu, Hua Kun; Guo, Zaiping

    2015-01-01

    Germanium is an outstanding anode material in terms of electrochemical performance, especially rate capability, but its developments are hindered by its high price because it is rare in the crust of earth, and its huge volume variation during the lithium insertion and extraction. Introducing other cheaper elements into the germanium-based material is an efficient way to dilute the high price, but normally sacrifice its electrochemical performance. By the combination of nanostructure design and cheap element (calcium) introduction, urchin-like Ca2Ge7O16 hierarchical hollow microspheres have been successfully developed in order to reduce the price and maintain the good electrochemical properties of germanium-based material. The electrochemical test results in different electrolytes show that ethylene carbonate/dimethyl carbonate/diethyl carbonate (3/4/3 by volume) with 5 wt% fluoroethylene carbonate additive is the most suitable solvent for the electrolyte. From the electrochemical evaluation, the as-synthesized Ca2Ge7O16 hollow microspheres exhibit high reversible specific capacity of up to 804.6 mA h g(-1) at a current density of 100 mA g(-1) after 100 cycles and remarkable rate capability of 341.3 mA h g(-1) at a current density of 4 A g(-1). The growth mechanism is proposed based on our experimental results on the growth process.

  17. Carbon-Coated Fe3O4/VOx Hollow Microboxes Derived from Metal-Organic Frameworks as a High-Performance Anode Material for Lithium-Ion Batteries.

    Science.gov (United States)

    Zhao, Zhi-Wei; Wen, Tao; Liang, Kuang; Jiang, Yi-Fan; Zhou, Xiao; Shen, Cong-Cong; Xu, An-Wu

    2017-02-01

    As the ever-growing demand for high-performance power sources, lithium-ion batteries with high storage capacities and outstanding rate performance have been widely considered as a promising storage device. In this work, starting with metal-organic frameworks, we have developed a facile approach to the synthesis of hybrid Fe3O4/VOx hollow microboxes via the process of hydrolysis and ion exchange and subsequent calcination. In the constructed architecture, the hollow structure provides an efficient lithium ion diffusion pathway and extra space to accommodate the volume expansion during the insertion and extraction of Li(+). With the assistance of carbon coating, the obtained Fe3O4/VOx@C microboxes exhibit excellent cyclability and enhanced rate performance when employed as an anode material for lithium-ion batteries. As a result, the obtained Fe3O4/VOx@C delivers a high Coulombic efficiency (near 100%) and outstanding reversible specific capacity of 742 mAh g(-1) after 400 cycles at a current density of 0.5 A g(-1). Moreover, a remarkable reversible capacity of 556 mAh g(-1) could be retained even at a current density of 2 A g(-1). This study provides a fundamental understanding for the rational design of other composite oxides as high-performance electrode materials for lithium-ion batteries.

  18. Unique Urchin-like Ca2Ge7O16 Hierarchical Hollow Microspheres as Anode Material for the Lithium Ion Battery

    Science.gov (United States)

    Li, Dan; Feng, Chuanqi; Liu, Hua Kun; Guo, Zaiping

    2015-06-01

    Germanium is an outstanding anode material in terms of electrochemical performance, especially rate capability, but its developments are hindered by its high price because it is rare in the crust of earth, and its huge volume variation during the lithium insertion and extraction. Introducing other cheaper elements into the germanium-based material is an efficient way to dilute the high price, but normally sacrifice its electrochemical performance. By the combination of nanostructure design and cheap element (calcium) introduction, urchin-like Ca2Ge7O16 hierarchical hollow microspheres have been successfully developed in order to reduce the price and maintain the good electrochemical properties of germanium-based material. The electrochemical test results in different electrolytes show that ethylene carbonate/dimethyl carbonate/diethyl carbonate (3/4/3 by volume) with 5 wt% fluoroethylene carbonate additive is the most suitable solvent for the electrolyte. From the electrochemical evaluation, the as-synthesized Ca2Ge7O16 hollow microspheres exhibit high reversible specific capacity of up to 804.6 mA h g-1 at a current density of 100 mA g-1 after 100 cycles and remarkable rate capability of 341.3 mA h g-1 at a current density of 4 A g-1. The growth mechanism is proposed based on our experimental results on the growth process.

  19. Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Marcus, R. Kenneth; Quarles, Jr., Charles Derrick; Russo, Richard E.; Koppenaal, David W.; Barinaga, Charles J.; Carado, Anthony J.

    2017-01-03

    A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).

  20. Hollow core-shell structured silicon@carbon nanoparticles embed in carbon nanofibers as binder-free anodes for lithium-ion batteries

    Science.gov (United States)

    Chen, Yanli; Hu, Yi; Shen, Zhen; Chen, Renzhong; He, Xia; Zhang, Xiangwu; Li, Yongqiang; Wu, Keshi

    2017-02-01

    Silicon is regarded as one of the most promising candidates for lithium-ion battery anodes owing to its large theoretical energy density (about 4200 mAh g-1) and low working potential (vs. Li/Li+). However, its practical application is limited by structure degradation and a comparatively poor capacity retention caused by large volume changes during cycling. In this study, we have prepared a novel nanofiber form of silicon/carbon with hollow core-shell structured silicon@carbon (Si@C) nanoparticles embedded in carbon nanofibers. Voids between the silicon nanoparticle (SiNP) core and carbon shell help to accommodate the volume expansion associated with the lithiation/delithiation process in a working electrode and allow formation of a stable solid electrolyte interphase (SEI) film. The obtained electrodes exhibited good cycle performance with a high reversible capacity of 1020.7 mAh g-1 after 100 cycles at a current density of 0.2 A g-1, and also delivered excellent cycling performance at a high current density of 3.2 A g-1. The design of this new structure provides a potential method for developing other functional composite anode materials with high reversible capacities and long-term cycle stabilities.

  1. Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples.

    Science.gov (United States)

    Es'haghi, Zarrin; Hoseini, Hasan Ali; Mohammadi-Nokhandani, Saeed; Ebrahimi, Javad

    2014-11-01

    A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol-gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV) using a hanging mercury drop electrode (HMDE) was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H)-one and 2-{[2-(2-Hydroxy-ethylamino)-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05-500 ng mL(-1) for Cd (II) and Pb (II). The limits of detection for lead and cadmium were 0.015 ng mL(-1) and 0.012 ng mL(-1), respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II) and Pb (II) in 5 mL of water sample, respectively.

  2. High-energy lithium-ion hybrid supercapacitors composed of hierarchical urchin-like WO3/C anodes and MOF-derived polyhedral hollow carbon cathodes.

    Science.gov (United States)

    Xu, Juan; Li, Yuanyuan; Wang, Lei; Cai, Qifa; Li, Qingwei; Gao, Biao; Zhang, Xuming; Huo, Kaifu; Chu, Paul K

    2016-09-22

    A lithium-ion hybrid supercapacitor (Li-HSC) comprising a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode has attracted much interest because it accomplishes a large energy density without compromising the power density. In this work, hierarchical carbon coated WO3 (WO3/C) with a unique mesoporous structure and metal-organic framework derived nitrogen-doped carbon hollow polyhedra (MOF-NC) are prepared and adopted as the anode and the cathode for Li-HSCs. The hierarchical mesoporous WO3/C microspheres assembled by radially oriented WO3/C nanorods along the (001) plane enable effective Li(+) insertion, thus exhibit high capacity, excellent rate performance and a long cycling life due to their high Li(+) conductivity, electronic conductivity and structural robustness. The WO3/C structure shows a reversible specific capacity of 508 mA h g(-1) at a 0.1 C rate (1 C = 696 mA h g(-1)) after 160 discharging-charging cycles with excellent rate capability. The MOF-NC achieved the specific capacity of 269.9 F g(-1) at a current density of 0.2 A g(-1). At a high current density of 6 A g(-1), 92.4% of the initial capacity could be retained after 2000 discharging-charging cycles, suggesting excellent cycle stability. The Li-HSC comprising a WO3/C anode and a MOF-NC cathode boasts a large energy density of 159.97 W h kg(-1) at a power density of 173.6 W kg(-1) and 88.3% of the capacity is retained at a current density of 5 A g(-1) after 3000 charging-discharging cycles, which are better than those previously reported for Li-HSCs. The high energy and power densities of the Li-HSCs of WO3/C//MOF-NC render large potential in energy storage.

  3. Studies of anode sheath phenomena in a Hall-effect thruster discharge

    Science.gov (United States)

    Dorf, Leonid

    2005-10-01

    Crossed electric and magnetic fields devices (plasma thrusters, magnetrons, coaxial plasma guns, plasma opening switches, etc.) are routinely used for plasma production and in other applications. Despite these numerous applications, the fundamental anode sheath phenomena in many of these devices have received surprisingly little experimental scrutiny. We chose a Hall-effect thruster (HT) discharge for our study of the anode sheath. It has been typically assumed in most fluid models of an HT that its steady-state operation requires the presence of a negative anode fall (electron-repelling anode sheath). Such anode fall behavior, opposite to that in typical glow discharges or hollow-anode plasma sources, is the result of a relatively high degree of ionization in HTs, achieved by applying a radial magnetic field transverse to the direction of the discharge current. Our data from non-perturbing probe measurements showed for the first time that the anode fall in HTs can be either negative or positive (electron-attracting anode sheath), depending on conditions at the anode surface. The path for current closure to the anode turns out to be quite subtle in HTs. This path determines the mechanism of the anode fall formation. In varying the magnetic field topology in the channel from a more uniform to a cusp-like one, we uncover intriguing results. For cusp configurations, in which the radial magnetic field changes polarity somewhere along the channel, the anode fall is positive, whereas it is negative for a more uniform field. This polarity difference could be attributed to the decreased electron mobility across the magnetic field in the cusp-like configuration. Our theoretical modeling of the anode sheath correlates well with the experimental results in describing how the magnitude of the sheath varies with the discharge voltage and mass flow rate.

  4. Modeling High Pressure Micro Hollow Cathode Discharges

    Science.gov (United States)

    2007-11-02

    cathode discharge excimer lamps , Phys. Plasmas 7, 286 (2000). [3] RH Stark and KH Schoenbach, Direct high pressure glow discharges, J. Appl. Phys...temperature profiles in argon glow discharges, J. Appl. Phys. 88, 2234 (2000) [8] M. Moselhy, W. Shi, R. Stark, A flat glow discharge excimer radiation...MHCD acts as a plasma cathode for a third electrode (anode). Some experimental results in this geometry are available for argon and for air from the

  5. High-pressure hollow cathode discharges

    Science.gov (United States)

    Schoenbach, Karl H.; El-Habachi, Ahmed; Shi, Wenhui; Ciocca, Marco

    1997-11-01

    Reducing the diameter of the cathode hole in a plane anode - hollow cathode geometry to 0963-0252/6/4/003/img1m has allowed us to generate direct current discharges in argon at atmospheric pressure. Up to pressure times cathode hole diameter (pD) values of approximately 5 Torr cm, and at sub-mA currents, glow discharges (predischarges) are observed with a shape which is determined by the vacuum electric field. In the same pD range, but at higher currents of up to approximately 4 mA, the discharges are of the hollow cathode discharge type. At pD values exceeding 5 Torr cm the predischarges turn into surface discharges along the mica spacer between the electrodes. At currents > 4 mA filamentary, pulsed discharges are observed. Qualitative information on the electron energy distribution in the microdischarges has been obtained by studying the VUV emission from ionized argon atoms and the argon excimer radiation at 130 nm. The results of the spectral measurements indicate the presence of a relatively large concentration of electrons with energies > 15 eV over the entire pressure range. The fact that the current - voltage characteristic of the microdischarges has a positive slope over much of the current range where excimer radiation is emitted indicates the possibility of forming arrays of these discharges and using them in flat panel excimer lamps.

  6. A Review on Chemical Effects in Aqueous Solution induced by Plasma with Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical effects in different aqueous solutions induced by plasma with glow dis charge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..

  7. Designed Functional Systems for High-Performance Lithium-Ion Batteries Anode: From Solid to Hollow, and to Core-Shell NiCo2O4 Nanoparticles Encapsulated in Ultrathin Carbon Nanosheets.

    Science.gov (United States)

    Peng, Liang; Zhang, Huijuan; Fang, Ling; Bai, Yuanjuan; Wang, Yu

    2016-02-01

    Binary metal oxides have been considered as ideal and promising anode materials, which can ameliorate and enhance the electrochemical performances of the single metal oxides, such as electronic conductivity, reversible capacity, and structural stability. In this research, we report a rational method to synthesize some novel sandwich-like NiCo2O4@C nanosheets arrays for the first time. The nanostructures exhibit the unique features of solid, hollow, and even core-shell NiCo2O4 nanoparticles encapsulated inside and a graphitized carbon layers coating outside. Compared to the previous reports, these composites demonstrate more excellent electrochemical performances, including superior rate capability and excellent cycling capacity. Therefore, the final conclusion would be given that these multifarious sandwich-like NiCo2O4@C composites could be highly qualified candidates for lithium-ion battery anodes in some special field, in which good capability and high capacity are urgently required.

  8. Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

    DEFF Research Database (Denmark)

    Canulescu, Stela; Molchan, Igor S.; Tauziede, C.

    2010-01-01

    A new method is presented for elemental and molecular analysis of halogen-containing samples by glow discharge time-of-flight mass spectrometry, consisting of detection of negative ions from a pulsed RF glow discharge in argon. Analyte signals are mainly extracted from the afterglow regime...... be used to study the distribution of a tantalum fluoride layer within the anodized tantala layer. Further, comparison is made with data obtained using glow-discharge optical emission spectroscopy, where elemental fluorine can only be detected using a neon plasma. The ionization mechanisms responsible...... for the formation of negative ions in glow discharge time-of-flight mass spectrometry are briefly discussed....

  9. Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr; Kumar, K. Kishor; Arnas, C. [Laboratoire de Physique des Interactions Ioniques et Moléculaires, CNRS, Aix-Marseille Université, 13397 Marseille (France)

    2014-12-15

    Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particles of more than a few tens of nanometres in diameter.

  10. Study of short atmospheric pressure dc glow microdischarge in air

    Science.gov (United States)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

    2011-10-01

    The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen

  11. Atmospheric Pressure Glow Discharge with Liquid Electrode

    Science.gov (United States)

    Tochikubo, Fumiyoshi

    2013-09-01

    Nonthermal atmospheric pressure plasmas in contact with liquid are widely studied aiming variety of plasma applications. DC glow discharge with liquid electrode is an easy method to obtain simple and stable plasma-liquid interface. When we focus attention on liquid-phase reaction, the discharge system is considered as electrolysis with plasma electrode. The plasma electrode will supply electrons and positive ions to the liquid surface in a different way from the conventional metal electrode. However, the phenomena at plasma-liquid interface have not been understood well. In this work, we studied physical and chemical effect in liquid induced by dc atmospheric pressure glow discharge with liquid electrode. The experiment was carried out using H-shaped Hoffman electrolysis apparatus filled with electrolyte, to separate the anodic and cathodic reactions. Two nozzle electrodes made of stainless steel are set about 2 mm above the liquid surface. By applying a dc voltage between the nozzle electrodes, dc glow discharges as plasma electrodes are generated in contact with liquid. As electrolyte, we used aqueous solutions of NaCl, Na2SO4, AgNO3 and HAuCl4. AgNO3 and HAuCl4 are to discuss the reduction process of metal ions for synthesis of nanoparticles (NPs). OH radical generation yield in liquid was measured by chemical probe method using terephthalic acid. Discharge-induced liquid flow was visualized by Schlieren method. Electron irradiation to liquid surface (plasma cathode) generated OH- and OH radical in liquid while positive ion irradiation (plasma anode) generated H+ and OH radical. The generation efficiency of OH radical was better with plasma anode. Both Ag NPs in AgNO3 and Au NPs in HAuCl4 were synthesized with plasma cathode while only Au NPs were generated with plasma anode. Possible reaction process is qualitatively discussed. The discharge-induced liquid flow such as convection pattern was strongly influenced by the gas flow on the liquid surface. This work

  12. Confined nanospace pyrolysis for the fabrication of coaxial Fe3O4@C hollow particles with a penetrated mesochannel as a superior anode for Li-ion batteries.

    Science.gov (United States)

    Lei, Cheng; Han, Fei; Sun, Qiang; Li, Wen-Cui; Lu, An-Hui

    2014-01-03

    In this study, a method is developed to fabricate Fe3O4@C particles with a coaxial and penetrated hollow mesochannel based on the concept of "confined nanospace pyrolysis". The synthesis involves the production of a polydopamine coating followed by a silica coating on a rod-shaped β-FeOOH nanoparticle, and subsequent treatment by using confined nanospace pyrolysis and silica removal procedures. Typical coaxial hollow Fe3O4@C possesses a rice-grain morphology and mesoporous structure with a large specific surface area, as well as a continuous and flexible carbon shell. Electrochemical tests reveal that the hollow Fe3O4@C with an open-ended nanostructure delivers a high specific capacity (ca. 864 mA h g(-1) at 1 A g(-1)), excellent rate capability with a capacity of about 582 mA h g(-1) at 2 A g(-1), and a high Coulombic efficiency (>97%). The excellent electrochemical performance benefits from the hollow cavity with an inner diameter of 18 nm and a flexible carbon shell that can accommodate the volume change of the Fe3O4 during the lithium insertion/extraction processes as well as the large specific surface area and open inner cavity to facilitate the rapid diffusion of lithium ions from electrolyte to active material. This fabrication strategy can be used to generate a hollow or porous metal oxide structure for high-performance Li-ion batteries. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges

    Energy Technology Data Exchange (ETDEWEB)

    Ha Yan [College of Mathematics and Computer Science, Hebei University, Baoding 071002 (China); Wang Huijuan [School of Mathematics and Physics, North China Electric Power University, Baoding 071003 (China); Wang Xiaofei [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2012-01-15

    Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.

  14. Multishelled NiO Hollow Spheres Decorated by Graphene Nanosheets as Anodes for Lithium-Ion Batteries with Improved Reversible Capacity and Cycling Stability

    Directory of Open Access Journals (Sweden)

    Lihua Chu

    2016-01-01

    Full Text Available Graphene-based nanocomposites attract many attentions because of holding promise for many applications. In this work, multishelled NiO hollow spheres decorated by graphene nanosheets nanocomposite are successfully fabricated. The multishelled NiO microspheres are uniformly distributed on the surface of graphene, which is helpful for preventing aggregation of as-reduced graphene sheets. Furthermore, the NiO/graphene nanocomposite shows much higher electrochemical performance with a reversible capacity of 261.5 mAh g−1 at a current density of 200 mA g−1 after 100 cycles tripled compared with that of pristine multishelled NiO hollow spheres, implying the potential application in modern science and technology.

  15. Cauliflower-like SnO2 hollow microspheres as anode and carbon fiber as cathode for high performance quantum dot and dye-sensitized solar cells

    Science.gov (United States)

    Ganapathy, Veerappan; Kong, Eui-Hyun; Park, Yoon-Cheol; Jang, Hyun Myung; Rhee, Shi-Woo

    2014-02-01

    Cauliflower-like tin oxide (SnO2) hollow microspheres (HMS) sensitized with multilayer quantum dots (QDs) as photoanode and alternative stable, low-cost counter electrode are employed for the first time in QD-sensitized solar cells (QDSCs). Cauliflower-like SnO2 hollow spheres mainly consist of 50 nm-sized agglomerated nanoparticles; they possess a high internal surface area and light scattering in between the microspheres and shell layers. This makes them promising photoanode material for both QDSCs and dye-sensitized solar cells (DSCs). Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) are used for QD-sensitizing the SnO2 microspheres. Additionally, carbon-nanofiber (CNF) with a unique structure is used as an alternative counter electrode (CE) and compared with the standard platinum (Pt) CE. Their electrocatalytic properties are measured using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Tafel-polarization. Under 1 sun illumination, solar cells made with hollow SnO2 photoanode sandwiched with the stable CNF CE showed a power conversion efficiency of 2.5% in QDSCs and 3.0% for DSCs, which is quite promising with the standard Pt CE (QDSCs: 2.1%, and DSCs: 3.6%).Cauliflower-like tin oxide (SnO2) hollow microspheres (HMS) sensitized with multilayer quantum dots (QDs) as photoanode and alternative stable, low-cost counter electrode are employed for the first time in QD-sensitized solar cells (QDSCs). Cauliflower-like SnO2 hollow spheres mainly consist of 50 nm-sized agglomerated nanoparticles; they possess a high internal surface area and light scattering in between the microspheres and shell layers. This makes them promising photoanode material for both QDSCs and dye-sensitized solar cells (DSCs). Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) are used for QD-sensitizing the SnO2 microspheres. Additionally, carbon-nanofiber (CNF) with a

  16. Effects of traces of molecular gases (hydrogen, nitrogen) in glow discharges in noble gases

    Science.gov (United States)

    Steers, E. B. M.; Smid, P.; Hoffmann, V.

    2008-07-01

    The "Grimm" type of low pressure glow discharge source, introduced some forty years ago, has proved to be a versatile analytical source. A flat sample is used as the cathode and placed about 0.2mm away from the end of a hollow tubular anode leading to an obstructed discharge. When the source was first developed, it was used for the direct analysis of solid metallic samples by optical emission spectroscopy (OES), normally with argon as the plasma gas; it was soon found that, using suitable electrical parameters, the cathode material was sputtered uniformly from a circular crater of diameter equal to that of the tubular anode, so that the technique could be used for compositional depth profile analysis (CDPA). Over the years the capability and applications of the technique have steadily increased. The use of rf powered discharges now permits the analysis of non-conducting layers and samples; improved instrumental design now allows CDPA of ever thinner layers (e.g. resolution of layers 5 nm thick in multilayer stacks is possible). For the original bulk material application, pre-sputtering could be used to remove any surface contamination but for CDPA, analysis must start immediately the discharge is ignited, so that any surface contamination can introduce molecular gases into the plasma gas and have significant analytical consequences, especially for very thin layers; in addition, many types of samples now analysed contain molecular gases as components (either as occluded gas, or e.g. as a nitride or oxide), and this gas enters the discharge when the sample is sputtered. It is therefore important to investigate the effect of such foreign gases on the discharge, in particular on the spectral intensities and hence the analytical results. The presentation will concentrate mainly on the effect of hydrogen in argon discharges, in the concentration range 0-2 % v/v but other gas mixtures (e.g. Ar/N_2, Ne/H_2) will be considered for comparison. In general, the introduction of

  17. Ion energy distributions for the identification of active species and processes in low pressure hollow cathode discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tanarro, I; Herrero, V J [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)], E-mail: itanarro@iem.cfmac.csic.es

    2009-08-15

    Energy distributions of ions generated in hollow cathode low pressures dc discharges of different gases and gas mixtures containing Ar, H{sub 2}, N{sub 2}, O{sub 2} or CH{sub 4} are studied by quadrupole mass spectrometry. The ions are sampled through a small diaphragm in the grounded cathode. The measured distributions are mostly determined by the acceleration of ions in the sheath region between the negative glow and the cathode, displaying in general a narrow peak centred at energies close to the anode potential, but with specific features for the distinct ions. It is shown that information about ion production and sheath collision processes can be derived from the shapes of the different energy distributions. In some cases these distributions are used for the estimation of the relative abundance of ions with the same mass/charge ratio but different compositions in complex gas mixtures.

  18. Dual phase Li4Ti5O12-TiO2 hierarchical hollow microspheres as anode materials for high rate lithium-ion batteries

    Science.gov (United States)

    Zhu, Kunxu; Hu, Guoxin

    2017-01-01

    Dual phase Li4Ti5O12-TiO2 hierarchical hollow microspheres composed of nanosheets are successfully fabricated by the calcination of hydrothermal product obtained from lithium peroxotitanate complex solution. Low-cost industrial H2TiO3 particles are chosen as titanium sources, which is significant for the inexpensive and large-scale production of Li4Ti5O12-TiO2 composite material. The Li4Ti5O12-TiO2 electrode yields excellent rate capability (151, 139 and 134 mA h g-1 at 10, 20 and 25 C, respectively) and good cycling stability (96% capacity retention after 500 cycles at 10 C). The mesoporous hierarchical morphology and high grain boundary density are likely the contributing factors to the excellent electrochemical performance of Li4Ti5O12-TiO2 composite.

  19. Immobilization of proteins on glow discharge treated polymers

    Science.gov (United States)

    Kiaei, D.; Safranj, A.; Chen, J. P.; Johnston, A. B.; Zavala, F.; Deelder, A.; Castelino, J. B.; Markovic, V.; Hoffman, A. S.

    Certain glow discharge-treated surfaces have been shown to enhance retention of adsorbed proteins. On the basis of this phenomenon, we have investigated the possibility of immobilizing (a) albumin for developing thromboresistant and non-fouling surfaces, (b) antibodies for immuno-diagnostic assays and (c) enzymes for various biosensors and industrial bioprocesses. Albumin retention was highest on surfaces treated with tetrafluoroethylene (TFE) compared to untreated surfaces or other glow discharge treatments studied. Preadsorption of albumin on TFE-treated surfaces resulted in low fibrinogen adsorption and platelet adhesion. IgG retention was also highest on TFE-treated surfaces. The lower detection limits of both malaria antigen and circulating anodic antigen of the schistosomiasis worm were enhanced following glow discharge treatment of the assay plates with TFE. Both TFE and tetrachloroethylene (TCE) glow discharge treated surfaces showed high retention of adsorbed horseradish peroxidase (HRP). However, the retained specific activity of HRP after adsorption on TCE-treated surfaces was remarkably higher than on TFE-treated surfaces.

  20. Progress in the understanding of non-1D glow discharges: experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Derouard, J. [Laboratoire de Spectrometrie Physique (UA CNRS 08), Universite Joseph Fourier (Grenoble-I), BP 87, 38402 Saint Martin d`Heres (France); Pitchford, L. [Centre de Physique des Plasmas et Applications de Toulouse (UA CNRS 277), Universite Paul Sabatier, 31062 Toulouse (France)

    1996-03-01

    This contribution is a joint presentation on the structure of non unidimensional glow discharges experimentally observed using in particular optical diagnostics and predicted using self consistent numerical models. Results are presented concerning the effect of radial losses and electrode edges on the structure of DC and RF glow discharges, and the inititation phase of the breakdown in planar hollow cathode discharges. Most of the observed features of the discharges can be well reproduced by the models, which thus can be used to predict the effect of geometry on plasma devices and guide the optimization of their design. {copyright} {ital 1996 American Institute of Physics.}

  1. Evolution of Multiple Double Layer in Glow discharge and its inherent Properties

    Science.gov (United States)

    Alex, Prince; A, Saravanan; Sinha, Suraj

    2016-10-01

    Formation and evolution of multiple anodic double layers (MADLs) were experimentally studied in glow discharge plasma. The boundary condition for the existence of MADL was identified in terms of threshold bias and ambient working pressure. The MADL formation is accompanied by an explosive growth in anode current and consequent current-voltage characteristics follows a hysteresis loop. The analysis yield that stable MADLs is only observed when the control voltage V2 is between a certain critical values (Vq > νte MADL completely transforms to an intense high current carrying unstable anode glow. The floating potential analysis carried out using three axially positioned electrostatic probes shows a bipolar signature of DL with as the control parameter is varied. The floating potential analysis also shows that hysteresis arises due to the difference in magnitude of electric field required to align the space charges in the DL sheet at the control voltage changes forward and backward. The effect of pressure on MADL indicates that the MADL structure advances towards anode surface as the pressure is increases. The power dumped (W) in the MADL is estimated to decrease with increase in pressure while the same increase in the anode glow.

  2. [Spatial distribution of electrons with high energy in atmospheric pressure glow discharge excited by DC voltage].

    Science.gov (United States)

    Liu, Zhi-qiang; Jia, Peng-ying; Liu, Tie

    2013-09-01

    Atmospheric pressure glow discharge excited by a DC voltage was realized in a 6 mm air gap by using a needle-water electrode discharge device. The atompheric pressure glow discharge has characteristic regions such as a cathode fall, a negative glow, a Faraday dark space, a positive column and an anode glow. The discharge is a normal glow through analyzing its voltage-current curve. The emission intensity of 337.1 nm spectral line from the second positive system of N2 was investigated because it can indicate the electron density with high energy. Results show that the maxima of high energy electrons appears in the vicinity of the needle tip, and it almost remains constant at other locations. The density of high energy electrons decreases with increasing the voltage. Similarly, it decreases with increasing the value of the ballast resistor. Oxygen atom is important for the sterilization and disinfection. The distribution of oxygen atom was also investigated by optical emission spectroscopy. It was found that the oxygen distribution is similar with the distribution of high energy electrons. These results are important for the application of atmospheric pressure glow discharge in environmental protection and biological treatment.

  3. Degradation of linear alkylbenzene sulfonate with contact glow discharge electrolysis

    Science.gov (United States)

    Budikania, Trisutanti; Ibrahim, Febiyanti, Irine Ayu; Utami, Nissa; Saksono, Nelson

    2015-12-01

    Contact Glow Discharge Electrolysis (CGDE) is one of electrolysis plasma technologies. CGDE can produce the hydroxyl radical in a large amount that can be used for wastewater degradation process. This study was conducted to obtain the influence of applied voltage, electrolyte concentration, and anode depth in the LAS degradation using CGDE and review its energy consumption. The greatest LAS degradation is achieved up to 99.14% with low energy consumption of 1149.88 kJ/mmol of the energy consumption that is obtained during 120 minutes by using 600 Volt, 0.02 M of KOH, and 0.5 cm of the anode depth and initial concentration of LAS is 100 ppm.

  4. Observation of mode transition and low-frequency oscillations in magnetically constricted anode

    Science.gov (United States)

    Chauhan, S.; Ranjan, M.; Bandyopadhyay, M.; Mukherjee, S.

    2016-12-01

    We report on the discharge behaviour and the mode transition observed in a magnetically constricted anode device. With an increase in pressure, the central droplet shaped glow shrunk and abruptly switched to peripheral glow mode for pressure above 5 ×10-2 mbar . This transition is observed when the width of the droplet shaped glow at the anode approaches the diameter of the central magnet. The mode transition is observed as a sudden jump in the discharge current, which obeys a different power law than the previous discharge mode. Further, this new mode is observed to accompany the global oscillations in the range of few kHz.

  5. Effect of a floating circular aperture on a dc glow discharge dusty plasma

    Science.gov (United States)

    Heinrich, Jonathon R.; Kim, Su-Hyun; Merlino, Robert L.

    2009-11-01

    We have investigated novel effects observed when a floating aperture, either 6 mm or 8 mm in diameter, is placed 1-2 cm in front of an anode disk (4 cm diameter) that is used to form a dc glow discharge dusty plasma. Dust is incorporated into the anode glow plasma from a tray located below the anode which contained kaolin powder. The glow discharge traps particles with an average size of 1 micron. When the aperture is placed in front of the disk, well-defined pear-shaped or spherical dust clouds are formed, depending on the diameter of the aperture and its distance from the anode. The dust interacts with the aperture through the potential structure associated with the floating (negative) plate in which the aperture is located. The dust cloud is imaged using a CCD camera and a thin sheet of 532 nm laser light. Some of the effects observed include: outwardly expanding spherical dust acoustic waves and shocks, dust rotation around a void formed at the aperture, and a dust/discharge instability in which the discharge is periodically quenched and reignited while the dust cloud expands and contracts, with the dust retaining a residual charge.

  6. High Pressure Micro-Slot Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    Wang Xinbing; Zhou Lina; Yao Xilin

    2005-01-01

    A direct current glow discharge source structure operating at high pressure based on the micro-slot hollow cathode is presented in this article. A 100 μm width slot cathode was fabricated of copper, and a stable DC glow discharge with an area of 0.5 mm2 was produced in noble gases (He, Ne) and air over a wide pressure range (kPa ~ 10 kPa). The current-voltage characteristics and the near UV radiation emission of the discharge were studied.

  7. Ion Nitriding of Titanium Alloys with a Hollow Cathode Effect Application

    Directory of Open Access Journals (Sweden)

    V.V. Budilov

    2015-09-01

    Full Text Available The method of ion nitriding the titanium VT6 alloy in glow discharge with the hollow cathode effect (HCE was investigated. Probe measurements of glow discharge plasma under HCE conditions and without it were performed; ion densities near the cathode surface were measured. The effect of HCE on microstructure, microhardness and wear resistance of VT6 alloy was determined. The technology of ion nitriding titanium alloys, based on phase modification of the surface layer in glow discharge with HCE, was developed.

  8. Simple synthesis of SnO2 hollow nanospheres and application in Lithium-ion battery anodes%SnO2纳米空心球的合成及在锂离子电池正极方面的应用

    Institute of Scientific and Technical Information of China (English)

    曹艳霞; 王万杰; 王经武; 陈荣峰

    2009-01-01

    采用锡盐溶液浸渍-煅烧锯末法,制备了SnO2纳米空心球.分别用X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及恒流充放电技术对产品的结构形态和电化学性质进行了表征.结果表明,SnO2空心球的尺寸在50~120nm之间,壳层厚度约为5nm.在作为锂离子电池正极使用时,初始放电容量为607.7 mAh g-1.%SnO2 hollow nanospheres were prepared by the simple heat treatment of sawdust impregnated by SnCl4 water solution in alkaline conditions. The crystallographic structure of the sample was determined by X-ray powder diffraction (XRD). The structure and morphology of these hollow SnO2 nanostructures were investigated by transmission electron microscopy (TEM) and high-resolution transmission electron micros-copy (HRTEM). The formation mechanism of SnO2 hollow sphere was studied by TEM preliminarily; it in-dicates that microspheres containing Sn-ion were formed in the impregnating process. The electrochemical Li-insertion of hollow SnO2 anodes were measured by the galvanostatic charge-discharge technique. Pre-liminary testing indicates that the initial charge capacity of 607.7 mAh g-1 is higher than that of carbon-based materials (theoretically 372.0 mAh g-1).

  9. Ignition and dynamics of high-voltage glow discharge plasma implantation

    Science.gov (United States)

    Fu, Ricky K. Y.; Chu, Paul K.; Tian, X. B.; Yang, S. Q.

    2006-01-01

    The self-ignition and dynamics of glow discharge plasma in the pulsed high-voltage plasma immersion ion implantation mode have been investigated. After ignition during the pulse-on period, the glow discharge continues to be sustained for a long period of time after the high-voltage pulse has been turned off as monitored by a Langmuir probe. The glow discharge and ignition lie on the left side of the Paschen curve when pd (gas pressure times electrode separation) is adjusted by using different anode to cathode distances utilizing a conducting grounded grid. The increased or constant implantation current Ia reveals that the ion sheath is stable and conforms to the cathode structure as the plasma density increases by one to two orders of magnitude towards the anode. In addition, the duration of the post-pulse-off plasma can be as long as several times of the pulse duration. The ignition time and duration of the plasma depend on the working pressure, applied voltage and pulse duration.

  10. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  11. Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air

    Science.gov (United States)

    Li, Xuechen; Zhao, Huanhuan; Jia, Pengying

    2013-11-01

    Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.

  12. Analysis Of The Different Zones Of Glow Discharge Of Ethyl Alcohol (C2H6O)

    Science.gov (United States)

    Torres, C.; Reyes, P. G.; Mulia, J.; Castillo, F.; Martínez, H.

    2014-05-01

    The aim of this work is to explore the emission spectroscopy of ethyl alcohol in some regions, also is determine the result elements of the glow discharge, the spectrums were observed in a range of 200 at 1100 nm in the different zones inside of the tube at different distances of 20 and 30 cm. The elements are: in anode region C6H5 (483.02nm), CHO (519.56nm) and H2 (560.47nm), in the positive column CO2+ (315.52 y 337.00nm), O+ (357.48nm), CH+ (380.61nm) and CO+ (399.73nm); in the cathode region we observed O+ (391.19nm), CHOCHO (428.00nm), CO+ (471.12nm) and H2 (656.52nm). C6H5, CHO y H2 species occurring in all regions analyzed varying the glow discharge emission intensity.

  13. Electron assisted glow discharges for conditioning fusion tokamak devices

    Science.gov (United States)

    Schaubel, K. M.; Jackson, G. L.

    1989-08-01

    Glow discharge conditioning of tokamaks with graphite plasma-facing surfaces has been used to reduce impurities and obtain density control of the plasma discharge. However, a major operational disadvantage of glow conditioning is the high pressure required to initiate the glow discharge, e.g., approx. 70 mTorr for helium in DIII-D, which requires isolating auxiliary components that can not tolerate the high pressure. An electron-gun assisted glow discharge can lower breakdown pressure, possibly eliminating the necessity of isolating these auxiliary systems during glow discharge conditioning and allowing glow discharge operation at lower pressures.

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

    Science.gov (United States)

    Alessi, James; Beebe, Edward; Carlson, Charles; McCafferty, Daniel; Pikin, Alexander; Ritter, John

    2014-02-01

    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.

  15. 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.

  16. On the increase in the limiting current of an atmospheric-pressure glow discharge in an argon flow

    Science.gov (United States)

    Baldanov, B. B.; Ranzhurov, Ts. V.

    2014-04-01

    The initiation of an atmospheric-pressure glow discharge (APGD) is studied in the multitip cathode-planar anode electrode system through which an argon flow passes. It is shown that sectioning of the cathode and ballast resistances present at corona tips make it possible to substantially expand the current region of the discharge and considerably raise the limiting current of the APGD. The shape of the coronafree electrode is found to influence the limiting discharge current.

  17. Hollow microporous organic capsules

    National Research Council Canada - National Science Library

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules...

  18. The Glowing Pickle and Other Vegetables

    Directory of Open Access Journals (Sweden)

    Ryan Burns

    2009-06-01

    Full Text Available The phenomenon known as the glowing pickle was investigated. Voltages ranging from 80-140 Volts AC were placed across a variety of vegetable specimens, both fresh and soaked in several salt solutions. The glowing was caused by electric arcing across a steam-filled cavity in the specimen. The emission spectra showed lines indicating the presence of potassium and sodium ions in the fresh specimens. In the specimens soaked in salt solutions, emission spectra matching the salt ions were observed.

  19. Analytical calculations of anode plasma position in high-voltage discharge range in case of auxiliary discharge firing

    OpenAIRE

    Melnyk, Igor V.; Tugay, S. B.

    2012-01-01

    We consider the mathematical model of triode high-voltage glow discharge range in case of auxiliary discharge firing. On a basis of analysis of elementary processes of charged particles interaction in a discharge range we obtain analytical relation, which allows to obtain the anode plasma position with regard to the cathode. Obtained results can be used for analysis of analysis of energy balance in a discharge range and self-maintained electron-ion optics of high voltage glow discharge electr...

  20. 二氧化锡中空球的制备及其电化学性能研究%Preparation and electrochemical properties of SnO_2 hollow spheres as an anode material for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    王继鹏; 丁玲红; 苏朝辉; 张盈; 张伟风

    2009-01-01

    SnO_2 hollow spheres were prepared using carbon spheres as template, SnCl_4 · 5H_2O and urea as precur-sors. Investigations of X-ray Diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission e-lectron microscopy (HRTEM) indicated that the products were SnO_2 hollow spheres with tetragonal structure; the average diameter and shell thickness were about 250 nm and 40 nm, respectively. The electrochemical properties of the SnO_2 hol-low spheres were investigated by galvanostatic cycling. The discharge capacity in the 1 st cycle was 1720mAh·g~(-1) at a current density of 160mA·g~(-1) (0. 2C) and the discharge capacity at 15st cycle was 615mAh·g~(-1), the coulombic efficien-cy were above 90% from the 4th cycle, which indicated that the SnO_2 hollow spheres had a higher high-lithium storage ca-pacity and excellent reversibility. The discharging capacity was about 588 mAh·g~(-1) at 15st cycle at a current density of 320mA· g~(-1) (0. 4C), demonstrating a good high-rate performance. Additionally, the easy of preparation and cheap price also made this method very promising in lithium-ion batteries.%用碳球做模板,SnCl_4·5H_2O和尿素为前驱体制备了二氧化锡(SnO_2)中空球.X射线衍射(XRD)、扫描电镜(SEM)和高分辨透射电镜(HRTEM)结果表明:制备出来的SnO_2中空球为四方相结构,其直径和壁厚分别约为250nm和40nm.恒电流充放电测试结果显示:在电流密度为160mAh·g~(-1)(0.20时,该SnO_2中空球的首次放电容量为1720mAh·g~(-1),第15周期放电容量保持到615mAh·g~(-1);从第4周期开始,库仑效率均保持在90%以上.电流密度为320mAh·g~1(0.4C)时,第15周期放电容量保持到588mAh·g~(-1).以上结果表明,这种材料具有较高的储锂容量和较好的可逆性能,是一种有前景的锂离子电池负极材料.

  1. Glow and pseudo-glow discharges in a surface discharge generator

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Dong Li-Fang; Wang Long

    2005-01-01

    The glow discharge in flowing argon at one atmospheric pressure is realized in a surface discharge generator. The discharge current presents one peak per half-cycle of the applied voltage. The duration of the discharge pulse is more than 1μs when the frequency of the applied voltage is 60kHz. For the glow discharge in argon, the power consumption increases with the increase of voltage or the decrease of gas pressure.This relation is explained qualitatively based on the theory of the Townsend breakdown mechanism. In contrast, the discharge current in one atmospheric pressure air gives many spikes in each half-cycle, and correspondingly this kind of discharge is called pseudo-glow discharge. Every current spike oscillates with high-frequency damping. The pseudo-glow discharge in one atmospheric pressure air might result from the streamer breakdown mechanism.

  2. Controlled thermal sintering of a metal-metal oxide-carbon ternary composite with a multi-scale hollow nanostructure for use as an anode material in Li-ion batteries.

    Science.gov (United States)

    Kim, Hwan Jin; Zhang, Kan; Choi, Jae-Man; Song, Min Sang; Park, Jong Hyeok

    2014-03-11

    We report a synthetic scheme for preparing a SnO2-Sn-carbon triad inverse opal porous material using the controlled sintering of Sn precursor-infiltrated polystyrene (PS) nanobead films. Because the uniform PS nanobead film, which can be converted into carbon via a sintering step, uptakes the precursor solution, the carbon can be uniformly distributed throughout the Sn-based anode material. Moreover, the partial carbonization of the PS nanobeads under a controlled Ar/oxygen environment not only produces a composite material with an inverse opal-like porous nanostructure but also converts the Sn precursor/PS into a SnO2-Sn-C triad electrode.

  3. Cathodic contact glow discharge electrolysis: its origin and non-faradaic chemical effects

    Science.gov (United States)

    Gupta, Susanta K. Sen; Singh, Rajshree

    2017-01-01

    Normal electrolysis (NE), at sufficiently high voltages, breaks down and undergoes a transition to a phenomenon called contact glow discharge electrolysis (CGDE) in which a sheath of glow discharge plasma encapsulates one of the electrodes, the anode or the cathode. The chemical effects of CGDE are highly non-faradaic e.g. a mixture of H2 and H2O2 plus O2 each in excess of the Faraday law value is liberated at the glow discharge plasma electrode from an aqueous electrolyte solution. Studies of cathodic CGDE, particularly its origin and chemical effects, in comparison to those of anodic CGDE have received significantly less attention and have not been studied in detail. The present paper is an attempt towards elucidation of the mechanisms of the growth of cathodic CGDE during NE and its non-faradaic chemical effects. The findings of the study have led to the inference that emission of secondary electrons from the metal cathode with sufficient kinetic energies, vaporization of the electrolyte solvent in the vicinity of the cathode surface induced by Joule heating and the onset of hydrodynamic instabilities in local vaporization contribute to the generation of the plasma at the cathode during NE. The findings have further shown that non-faradaic yields of CGDE at the cathode originate from energy transfer processes in two reaction zones: a plasma phase reaction zone around the cathode which accounts for ~75% of the yields, and a liquid phase reaction zone near the plasma-catholyte solution interface accounting for the remaining ~25% of the yields.

  4. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    Science.gov (United States)

    Ahadi, Amir Mohammad; Trottenberg, Thomas; Rehders, Stefan; Strunskus, Thomas; Kersten, Holger; Faupel, Franz

    2015-08-01

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  5. Hollow dimension of modules

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In this paper, we are interested in the following general question: Given a module Mwhich has finite hollow dimension and which has a finite collection of submodules Ki (1≤i≤n) such that M=K1+... +Kn, can we find an expression for the hollow dimension of Min terms of hollow dimensions of modules built up in some way from K1 Kn? We prove the following theorem:Let Mbe an amply supplemented module having finite hollow dimension and let Ki (1≤i≤n) be a finite collection of submodules of Msuch that M=K1+...+Kn. Then the hollow dimension h(M) of Mis the sum of the hollow dimensions of Ki (1≤i≤n) ifand only if Ki is a supplement of K1+...+Ki-1+Ki+1+...+Kn in Mfor each 1≤i≤n.

  6. Non-linear macro evolution of a dc driven micro atmospheric glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn [The State Key Laboratory on Fiber Optic Local Area, Communication Networks and Advanced Optical Communication Systems, Key Laboratory for Laser Plasmas and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-10-15

    We studied the macro evolution of the micro atmospheric glow discharge generated between a micro argon jet into ambient air and static water. The micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors are found for the micro discharge when the water acts as a cathode, different from the discharge when water behaves as an anode. Groups of snapshots of the micro discharge formed at different discharge currents are captured by an intensified charge-coupled device with controlled exposure time, and each group consisted of 256 images taken in succession. Edge detection methods are used to identify the water surface and then the total brightness is defined by adding up the signal counts over the area of the micro discharge. Motions of the water surface at different discharge currents show that the water surface lowers increasingly rapidly when the water acts as a cathode. In contrast, the water surface lowers at a constant speed when the water behaves as an anode. The light curves are similar to logistic growth curves, suggesting that a self-inhibition process occurs in the micro discharge. Meanwhile, the total brightness increases linearly during the same time when the water acts as an anode. Discharge-water interactions cause the micro discharge to evolve. The charged particle bomb process is probably responsible for the different behaviors of the micro discharges when the water acts as cathode and anode.

  7. Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

    Science.gov (United States)

    Mason, Rod S; Mitchell, David J; Dickinson, Paul M

    2010-04-21

    Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical

  8. Preparation of SnO 2 /Carbon Composite Hollow Spheres and Their Lithium Storage Properties

    KAUST Repository

    Lou, Xiong Wen

    2008-10-28

    In this work, we present a novel concept of structural design for preparing functional composite hollow spheres and derived double-shelled hollow spheres. The approach involves two main steps: preparation of porous hollow spheres of one component and deposition of the other component onto both the interior and exterior surfaces of the shell as well as in the pores. We demonstrate the concept by preparing SnO2/carbon composite hollow spheres and evaluate them as potential anode materials for lithium-ion batteries. These SnO2/carbon hollow spheres are able to deliver a reversible Li storage capacity of 473 mA h g-1 after 50 cycles. Unusual double-shelled carbon hollow spheres are obtained by selective removal of the sandwiched porous SnO2 shells. © 2008 American Chemical Society.

  9. Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

    OpenAIRE

    Landl, N. V.; Korolev, Yuriy Dmitrievich; Frants, O. B.; Geyman, V. G.; Bolotov, A. V.

    2015-01-01

    The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the ...

  10. Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

    Science.gov (United States)

    Landl, N. V.; Korolev, Y. D.; Frants, O. B.; Geyman, V. G.; Bolotov, A. V.

    2015-11-01

    The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the current-voltage characteristics of the discharge have been interpreted.

  11. Photoelectrochemical evidence of nitrogen incorporation during anodizing sputtering--deposited Al-Ta alloys.

    Science.gov (United States)

    Zaffora, A; Santamaria, M; Di Franco, F; Habazaki, H; Di Quarto, F

    2016-01-01

    Anodic films were grown to 20 V on sputtering-deposited Al-Ta alloys in ammonium biborate and borate buffer solutions. According to glow discharge optical emission spectroscopy, anodizing in ammonium containing solution leads to the formation of N containing anodic layers. Impedance measurements did not evidence significant differences between the dielectric properties of the anodic films as a function of the anodizing electrolyte. Photoelectrochemical investigation allowed evidencing that N incorporation induces a red-shift in the light absorption threshold of the films due to the formation of allowed localized states inside their mobility gap. The estimated Fowler threshold for the internal photoemission processes of electrons resulted to be independent of the anodizing electrolyte confirming that N incorporation does not appreciably affect the density of states distribution close to the conduction band mobility edge. The transport of photogenerated carriers has been rationalized according to the Pai-Enck model of geminate recombination.

  12. Simulation of transition from Townsend mode to glow discharge mode in a helium dielectric barrier discharge at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Niu Dong-Ying; Xu Long-Fei; Jia Peng-Ying; Chang Yuan-Yuan

    2012-01-01

    The dielectric barrier discharge characteristics in helium at atmospheric pressure are simulated based on a one-dimensional fluid model.Under some discharge conditions,the results show that one discharge pulse per half voltage cycle usually appears when the amplitude of external voltage is low,while a glow-like discharge occurs at high voltage.For the one discharge pulse per half voltage cycle,the maximum of electron density appears near the anode at the beginning of the discharge,which corresponds to a Townsend discharge mode.The maxima of the electron density and the intensity of electric field appear in the vicinity of the cathode when the discharge current increases to some extent,which indicates the formation of a cathode-fall region.Therefore,the discharge has a transition from the Townsend mode to the glow discharge mode during one discharge pulse,which is consistent with previous experimental results.

  13. Formation of Triple-Shelled Molybdenum-Polydopamine Hollow Spheres and Their Conversion into MoO2 /Carbon Composite Hollow Spheres for Lithium-Ion Batteries.

    Science.gov (United States)

    Wang, Yawen; Yu, Le; Lou, Xiong Wen David

    2016-11-14

    Unique triple-shelled Mo-polydopamine (Mo-PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self-templating mechanism for the multi-shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo-glycerate templates. These triple-shelled Mo-PDA hollow spheres can be converted to triple-shelled MoO2 /carbon composite hollow spheres by thermal treatment. Owing to the unique multi-shells and hollow interior, the as-prepared MoO2 /carbon composite hollow spheres exhibit appealing performance as an anode material for lithium-ion batteries, delivering a high capacity of ca. 580 mAh g(-1) at 0.5 A g(-1) with good rate capability and long cycle life. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Time dependent argon glow discharge treatment of Al-alloy samples

    Indian Academy of Sciences (India)

    Sunanda J Karandikar; S V Gogawale; A K Dua; K K Kutty

    2001-05-01

    Aluminium alloy ultra-high vacuum system provides a convenient tool to access the UHV region due to short pump down time, its reduced weight, low cost etc. For UHV systems, aluminium and its alloys are preferred materials to stainless steel. A cylindrical discharge chamger of SS 304 with various ports on it, evacuated by turbomoleculer pumping unit is used in the experimental system. A hollow cathode de glow discharge in argon for different time durations is used to treat chemically cleaned ASA 6063 aluminium alloy samples, keeping all other parameters constant. The scanning electron microscope (SEM) is used to examine processed surfaces and to study topographical features. The energy dispersive microanalysis by X-rays (EDX) is used to determine the elemental composition of the samples. The results indicate the physical sputtering taking place in Ar GDC. The etched area increases with discharge time duration. The EDX spectrum shows the inconsistency in weight percentage of various elements of Al-alloy.

  15. Stability of atmospheric pressure glow discharges

    Science.gov (United States)

    Chirokov, Alexandre V.

    There has been a considerable interest in non-thermal atmospheric pressure discharges over the past decade due to increased number of industrial applications. Although non-thermal atmospheric pressure discharges have been intensively studied for the past century the clear physical picture of these discharges is far from being complete. Spontaneous transition of non-thermal atmospheric pressure discharges to thermal discharge and discharge filamentation are among least understood plasma phenomena. The discharge stability and reliable control of plasma parameters are highly desirable for numerous applications. This study focuses on stability of atmospheric pressure glow discharges with respect to filamentation and arcing. Atmospheric pressure glow discharge (APG) is the newest and the most promising addition to the family of non-thermal atmospheric pressure discharges. However this discharge is very susceptible to thermal instability which causes arcing, loss of uniformity and significant damage to electrodes. Suppression of thermal instability and effective control of discharge parameters is critical for industrial applications. A model was developed to understand transition to arc in atmospheric pressure glow discharges. APG discharges that operate in pure helium and in helium with addition of oxygen and nitrogen were considered in these studies. Simulation results indicate that arcing is the result of sheath breakdown rather than thermal instability. It was shown that although sheath breakdown is always followed by overheating the transition to arc in atmospheric glow discharges is not a result of thermal instability. In second part of this research interaction between plasma filaments in dielectric barrier discharges has been studied. This interaction is responsible for the formation of microdischarge patterns reminiscent of two-dimensional crystals. Depending on the application, microdischarge patterns may have a significant influence on DBD performance

  16. A photometric model for predicting the sky glow of greenhouses

    NARCIS (Netherlands)

    Alferdinck, J.W.A.M.; Janssen, E.G.O.N.; Zonneveldt, L.; Ruigrok, J.

    2006-01-01

    many greenhouses use artificial light to grow plants. Part of this light escapes, scatters in the sky and causes sky glow. Residents in the vicinity complain about the absence of natural darkness. A light scatter model is developed in order to quantify the dose of the sky glow. The luminance of the

  17. Electron heating in atmospheric pressure glow discharges

    Science.gov (United States)

    Stark, Robert H.; Schoenbach, Karl H.

    2001-04-01

    The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K have been performed to explore the electron heating effect. Measurements of the temporal development of the voltage across the discharge and the optical emission in the visible after applying a 10 ns high voltage pulse to a weakly ionized steady state plasma demonstrated increasing plasma decay times from tens of nanoseconds to microseconds when the pulsed electric field was raised from 10 to 40 kV/cm. Temporally resolved photographs of the discharge have shown that the plasma column expands during this process. The nonlinear electron heating effect can be used to reduce the power consumption in a repetitively operated air plasma considerably compared to a dc plasma operation. Besides allowing power reduction, pulsed electron heating also has the potential to enhance plasma processes, which require elevated electron energies, such as excimer generation for ultraviolet lamps.

  18. Glow discharge based device for solving mazes

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation); Sarov Institute of Physics and Technology (SarFTI) of National Research Nuclear University “MEPhI,” Sarov, Nizhni Novgorod region 607188 (Russian Federation); Maksimov, Artem N.; Pylayev, Nikolay A. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation)

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  19. Acting green elicits a literal warm glow

    Science.gov (United States)

    Taufik, Danny; Bolderdijk, Jan Willem; Steg, Linda

    2015-01-01

    Environmental policies are often based on the assumption that people only act environmentally friendly if some extrinsic reward is implicated, usually money. We argue that people might also be motivated by intrinsic rewards: doing the right thing (such as acting environmentally friendly) elicits psychological rewards in the form of positive feelings, a phenomenon known as warm glow. Given the fact that people's psychological state may affect their thermal state, we expected that this warm glow could express itself quite literally: people who act environmentally friendly may perceive the temperature to be higher. In two studies, we found that people who learned they acted environmentally friendly perceived a higher temperature than people who learned they acted environmentally unfriendly. The underlying psychological mechanism pertains to the self-concept: learning you acted environmentally friendly signals to yourself that you are a good person. Together, our studies show that acting environmentally friendly can be psychologically rewarding, suggesting that appealing to intrinsic rewards can be an alternative way to encourage pro-environmental actions.

  20. Engineering Stable Hollow Capsules

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    @@ Scientists at the CAS Institute of Chemistry have been succeeded in fabricating stable hollow capsules by extending covalent layer-by-layer self-assembly(CSA)technique from 2-dimensional to 3-dimensional systems.

  1. Hollow-Fiber Clinostat

    Science.gov (United States)

    Rhodes, Percy H.; Miller, Teresa Y.; Snyder, Robert S.

    1990-01-01

    Hollow-fiber clinostat, is bioreactor used to study growth and other behavior of cells in simulated microgravity. Cells under study contained in porous hollow fiber immersed in culture medium inside vessel. Bores in hollow fiber allow exchange of gases, nutrients, and metabolic waste products between living cells and external culture media. Hollow fiber lies on axis of vessel, rotated by motor equipped with torque and speed controls. Desired temperature maintained by operating clinostat in standard tissue-culture incubator. Axis of rotation made horizontal or vertical. Designed for use with conventional methods of sterilization and sanitation to prevent contamination of specimen. Also designed for asepsis in assembly, injection of specimen, and exchange of medium.

  2. Some properties of a microwave boosted glow discharge source using neon as the operating gas.

    Science.gov (United States)

    Leis, F; Steers, E B

    1996-07-01

    The use of neon as the operating gas for the analysis of aluminium samples with the microwave boosted glow discharge source has been studied. A new type of anode tube allowed the gas to enter the source near the sample surface so that more material was transported into the discharge. Erosion rates have been measured under conditions optimised for high line-to-background ratios and found to be lower than with argon (9 and 21 n/s, respectively). Despite the lower erosion rate the detection limits measured for a number of elements in aluminium are in the range 0.02-1 microg/g and comparable to those obtained with argon as the operating gas.

  3. Low-pressure glow discharge in a Xenon/Chlorine mixture

    Science.gov (United States)

    Shuaibov, A. K.; Shimon, L. L.; Shevera, I. V.; Dashchenko, A. I.

    2002-12-01

    The spatial, electrical, and optical characteristics of a transverse glow discharge and a volume discharge with a spherical anode and plane cathode in low-pressure Xe/Cl2 mixtures are studied. It is shown that the transverse glow discharge in mixtures with a low chlorine content occupies most of the interelectrode gap and exists in the form of strata. As the total pressure ( P≥300 Pa) and the partial chlorine pressure ( P(Cl2)≥80 Pa) increase, a solitary plasma domain with a volume of 1-2 cm3 forms in the discharge gap. It acts as a selective source of UV radiation in the XeCl(D-X) 236-nm, Cl2 (D'-A') 257-nm, and XeCl(B-X) 308-nm bands. In certain Xe/Cl2 mixtures, plasma self-oscillations in the frequency range 1-100 kHz are observed. The current of a low-pressure volume discharge with a spherical anode and plane cathode and the emission from it have both a dc and an ac component. The pressure and composition of the working mixture, as well as the average current of the volume discharge are optimized to attain the maximum emission intensity of the XeCl(D,B-X) bands. Low-pressure volume discharges in xenon/chlorine mixtures can be used as active media in low-pressure large-aperture planar or cylindrical excimer-halogen lamps emitting modulated or repetitive pulsed UV radiation.

  4. Advances in aluminum anodizing

    Science.gov (United States)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  5. Probiotic bacteria induce a 'glow of health'.

    Directory of Open Access Journals (Sweden)

    Tatiana Levkovich

    Full Text Available Radiant skin and hair are universally recognized as indications of good health. However, this 'glow of health' display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health.

  6. Zinc anode alloy for sacrificial anodes

    Energy Technology Data Exchange (ETDEWEB)

    Jore, T.N.

    1984-02-13

    A zinc anode for sacrifical anodes, for preventing intercrystalline corrosion, comprises 0.10-050% by weight Al, 0.025-1.15% by weight Cd, and the remainder zinc and impurities caused by the production method, wherein the alloy also contains 0.01-1.0% magnesium.

  7. A model for explaining some features of shuttle glow

    Science.gov (United States)

    Peters, P. N.

    1985-01-01

    A solid state model is proposed which hopefully removes some of the objections to excited atoms being sources for light emanating from surfaces. Glow features are discussed in terms of excited oxygen atoms impinged on the surface, although other species could be treated similarly. Band formation, excited lifetime shortening and glow color are discussed in terms of this model. The model's inability to explain glow emanating above surfaces indicates a necessity for other mechanisms to satisfy this requirements. Several ways of testing the model are described.

  8. Spectrochemical analysis with DC glow discharges at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Broekaert, J.A.C., E-mail: jose.broekaert@chemie.uni-hamburg.de; Reinsberg, K.-G.

    2015-04-01

    A review on recent work and developments in dc glow discharges at atmospheric pressure when used as radiation sources for optical atomic spectrometry and mass spectrometry is given. Diagnostics and analytical features of dc glow discharges at atmospheric pressure between conductive solid electrodes as well as with a liquid as the cathode and flowing afterglow sources were described. Possibilities for the introduction of analytes in solutions, in the gaseous state and direct solids sampling were discussed. - Highlights: • The state-of-the-art and trends of development of dc glow discharges at atmospheric pressure for spectrochemical analysis are discussed.

  9. Structure of anodized Al–Zr sputter deposited coatings and effect on optical appearance

    Energy Technology Data Exchange (ETDEWEB)

    Gudla, Visweswara Chakravarthy [Department of Mechanical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Canulescu, Stela [Department of Photonics Engineering, Technical University of Denmark, DK-4000 Roskilde (Denmark); Shabadi, Rajashekhara [Unité Matériaux et Transformations, Université Lille1, 59655 Villeneuve ‘Ascq (France); Rechendorff, Kristian [Tribology Centre, Danish Technological Institute, DK-8000 Århus C (Denmark); Dirscherl, Kai [Danish Fundamental Metrology, DK-2800 Kgs., Lyngby (Denmark); Ambat, Rajan, E-mail: ram@mek.dtu.dk [Department of Mechanical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2014-10-30

    Highlights: • Microstructure of magnetron sputtered Al–Zr coatings on AA6060 under as coated and heat treated condition. • Effect of heat treatment and precipitation of Al–Zr–Si (τ{sub 1}) phase on optical appearance of anodized layer. • Partial oxidation of τ{sub 1} precipitates after anodizing and relation to darkening of the anodized layer. • Oxidized region of τ{sub 1} precipitates was amorphous while unoxidized region retained crystallinity. • Unoxidized metallic τ{sub 1} in amorphous anodic alumina acts as light absorption centres and causes darkening after anodizing. - Abstract: The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al–Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result in the evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550 °C for 4 h in order to evolve Al–Zr based second phase precipitates in the microstructure. Anodizing was performed using 20 wt.% sulphuric acid at 18 °C with an intention to study the effect of anodizing on the Al–Zr based precipitates in the coating. Detailed microstructural characterization of the coating and anodized layer was carried out using high resolution scanning and transmission electron microscopy, grazing incidence X-ray diffraction analysis, glow discharge optical emission spectroscopy, and optical appearance using spectrophotometry. The evolution of microstructure in the anodized layer as a function of anodizing parameters and their influence on the interaction of light is investigated and the results in general are applicable to discolouration of anodized layer on

  10. Nanoporous silicon flakes as anode active material for lithium-ion batteries

    Science.gov (United States)

    Kim, Young-You; Lee, Jeong-Hwa; Kim, Han-Jung

    2017-01-01

    Nanoporous-silicon (np-Si) flakes were prepared using a combination of an electrochemical etching process and an ultra-sonication treatment and the electrochemical properties were studied as an anode active material for rechargeable lithium-ion batteries (LIBs). This fabrication method is a simple, reproducible, and cost effective way to make high-performance Si-based anode active materials in LIBs. The anode based on np-Si flakes exhibited a higher performances (lower capacity fade rate, stability and excellent rate capability at high C-rate) than the anode based on Si nanowires. The excellent performance of the np-Si flake anode was attributed to the hollowness (nanoporous structure) of the anode active material, which allowed it to accommodate a large volume change during cycling.

  11. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  12. Multifunctional Glow Discharge Analyzer for Spacecraft Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and Penn State University (PSU) propose to develop a highly sensitive spectrometer based on glow discharge emission for the...

  13. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    Science.gov (United States)

    1994-01-01

    This 35mm frame, photographed as the Space Shuttle Columbia was orbiting Earth during a 'night' pass, documents the glow phenomenon surrounding the vertical stabilizer and the Orbital Maneuvering System (OMS) pods of the spacecraft.

  14. High-capacity nanocarbon anodes for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haitao; Sun, Xianzhong; Zhang, Xiong; Lin, He; Wang, Kai; Ma, Yanwei, E-mail: ywma@mail.iee.ac.cn

    2015-02-15

    Highlights: • The nanocarbon anodes in lithium-ion batteries deliver a high capacity of ∼1100 mA h g{sup −1}. • The nanocarbon anodes exhibit excellent cyclic stability. • A novel structure of carbon materials, hollow carbon nanoboxes, has potential application in lithium-ion batteries. - Abstract: High energy and power density of secondary cells like lithium-ion batteries become much more important in today’s society. However, lithium-ion battery anodes based on graphite material have theoretical capacity of 372 mA h g{sup −1} and low charging-discharging rate. Here, we report that nanocarbons including mesoporous graphene (MPG), carbon tubular nanostructures (CTN), and hollow carbon nanoboxes (HCB) are good candidate for lithium-ion battery anodes. The nanocarbon anodes have high capacity of ∼1100, ∼600, and ∼500 mA h g{sup −1} at 0.1 A g{sup −1} for MPG, CTN, and HCB, respectively. The capacity of 181, 141, and 139 mA h g{sup −1} at 4 A g{sup −1} for MPG, CTN, and HCB anodes is retained. Besides, nanocarbon anodes show high cycling stability during 1000 cycles, indicating formation of a passivating layer—solid electrolyte interphase, which support long-term cycling. Nanocarbons, constructed with graphene layers which fulfill lithiation/delithiation process, high ratio of graphite edge structure, and high surface area which facilitates capacitive behavior, deliver high capacity and improved rate-capability.

  15. tgcd: An R package for analyzing thermoluminescence glow curves

    Science.gov (United States)

    Peng, Jun; Dong, ZhiBao; Han, FengQing

    Thermoluminescence (TL) glow curves are widely used in dosimetric studies. Many commercial and free-distributed programs are used to deconvolute TL glow curves. This study introduces an open-source R package tgcd to conduct TL glow curve analysis, such as kinetic parameter estimation, glow peak simulation, and peak shape analysis. TL glow curves can be deconvoluted according to the general-order empirical expression or the semi-analytical expression derived from the one trap-one recombination center (OTOR) model based on the Lambert W function by using a modified Levenberg-Marquardt algorithm from which any of the parameters can be constrained or fixed. The package provides an interactive environment to initialize parameters and offers an automated "trial-and-error" protocol to obtain optimal fit results. First-order, second-order, and general-order glow peaks (curves) are simulated according to a number of simple kinetic models. The package was developed using a combination of Fortran and R programming languages to improve efficiency and flexibility.

  16. Non-linear macro evolution of a dc driven micro atmospheric glow discharge

    CERN Document Server

    Xu, Shaofeng

    2015-01-01

    We studied the macro evolution of the micro atmospheric glow discharge generated between a micro argon jet into ambient air and static water. The micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors are found for the micro discharge when the water acts as a cathode, different from the discharge when water behaves as an anode. Groups of snapshots of the micro discharge formed at different discharge currents are captured by an intensified charge-coupled device with controlled exposure time, and each group consisted of 256 images taken in succession. Edge detection methods are used to identify the water surface and then the total brightness is defined by adding up the signal counts over the area of the micro discharge. Motions of the water surface at different discharge currents show that the water surface lowers increasingly rapidly when the water acts as a cathode. In contrast, the water surface lowers at a constant speed when the water behaves as an anode. The light curves are simila...

  17. Nanotubes within transition metal silicate hollow spheres: Facile preparation and superior lithium storage performances

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan; An, Yongling; Zhai, Wei; Gao, Xueping [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Feng, Jinkui, E-mail: jinkui@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Ci, Lijie [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Xiong, Shenglin [School of Materials Science and Engineering, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-10-15

    Highlights: • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were successfully prepared by a facile hydrothermal method using SiO{sub 2} nanosphere. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were tested as anode materials for lithium batteries. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} delivered superior electrochemical performance. • The lithium storage mechanism is probe via cyclic voltammetry and XPS. - Abstract: A series of transition metal silicate hollow spheres, including cobalt silicate (Co{sub 2}SiO{sub 4}), manganese silicate (MnSiO{sub 3}) and copper silicate (CuSiO{sub 3}.2H{sub 2}O, CuSiO{sub 3} as abbreviation in the text) were prepared via a simple and economic hydrothermal method by using silica spheres as chemical template. Time-dependent experiments confirmed that the resultants formed a novel type of hierarchical structure, hollow spheres assembled by numerous one-dimensional (1D) nanotubes building blocks. For the first time, the transition metal silicate hollow spheres were characterized as novel anode materials of Li-ion battery, which presented superior lithium storage capacities, cycle performance and rate performance. The 1D nanotubes assembly and hollow interior endow this kind of material facilitate fast lithium ion and electron transport and accommodate the big volume change during the conversion reactions. Our study shows that low-cost transition metal silicate with rationally designed nanostructures can be promising anode materials for high capacity lithium-ion battery.

  18. Advances in the Remote Glow Discharge Experiment

    Science.gov (United States)

    Dominguez, Arturo; Zwicker, A.; Rusaits, L.; McNulty, M.; Sosa, Carl

    2014-10-01

    The Remote Glow Discharge Experiment (RGDX) is a DC discharge plasma with variable pressure, end-plate voltage and externally applied axial magnetic field. While the experiment is located at PPPL, a webcam displays the live video online. The parameters (voltage, magnetic field and pressure) can be controlled remotely in real-time by opening a URL which shows the streaming video, as well as a set of Labview controls. The RGDX is designed as an outreach tool that uses the attractive nature of a plasma in order to reach a wide audience and extend the presence of plasma physics and fusion around the world. In March 2014, the RGDX was made publically available and, as of early July, it has had approximately 3500 unique visits from 107 countries and almost all 50 US states. We present recent upgrades, including the ability to remotely control the distance between the electrodes. These changes give users the capability of measuring Paschen's Law remotely and provides a comprehensive introduction to plasma physics to those that do not have access to the necessary equipment.

  19. Experimental study of soft X-ray intensity with different anode tips in Amirkabir plasma focus device

    Indian Academy of Sciences (India)

    HABIBI MORTEZA; MAHTAB MAHSA

    2016-07-01

    To study the effect of different anode tip geometries on the intensity of soft X-rays emitted from a 4 kJ plasma focus device (PFD), we considered five different anode tips which were cylindrical-flat, cylindricalhollow, spherical-convex, cone-flat and cone-hollow tips. BPX-65 PIN diodes covered by four different filters are used to register the intensity of soft X-rays. The use of cone-flat anode tip has augmented the emitted X-ray three times compared to the conventional cylindrical-flat anode.

  20. Experimental investigation of a capacitive blind hollow cathode discharge with central gas injection

    Science.gov (United States)

    Hoffmann, D.; Müller, M.; Petkow, D.; Herdrich, G.; Lein, S.

    2014-12-01

    The operating parameters and resulting plasma properties of a blind hollow cathode (BHC) discharge have been investigated. The hollow cathode was driven capacitively with a pulsed dc signal of 200 kHz in a power range between 50 and 100 W at an ambient pressure of about 10 Pa. The working gas was argon, which was introduced with a ceramic capillary at different positions of the longitudinal axis of the hollow cathode with flow rates of between 30 and 1000 sccm. The current-voltage characteristics were recorded. The pressure at the end of the BHC was measured with a miniaturized pressure transducer with varying volumetric flow rate and axial position of the capillary in the hollow cathode. To characterize the ignition behaviour of the system, the measured breakdown voltages were compared with phenomenological Paschen curves calculated from the pressure data. Optical emission spectroscopy was used to examine the origins of the light emission, comparing the glow mode and hollow cathode mode in particular. A high-speed camera recorded some plasma processes. A mounting with an indium tin oxide coated glass was used to observe the inner volume of the BHC along the longitudinal axis, while the plasma was operated with different parameters. The optical observations revealed an inhomogeneous plasma condition along the axis.

  1. Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies July 2001 to May 2013

    Science.gov (United States)

    Kamhawi, Hani; Yim, John T.; Patterson, Michael J.; Dalton, Penni J.

    2013-01-01

    The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the on-orbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally.

  2. Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies from July 2011 to May 2013

    Science.gov (United States)

    Kamhawi, Hani; Yim, John T.; Patterson, Michael J.; Dalton, Penni J.

    2014-01-01

    The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the onorbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally.

  3. Rational synthesis of carbon-coated hollow Ge nanocrystals with enhanced lithium-storage properties

    Science.gov (United States)

    Zhang, Wei; Chu, Xiaoqing; Chen, Chaoji; Xiang, Jingwei; Liu, Xiaoxiao; Huang, Yunhui; Hu, Xianluo

    2016-06-01

    High-capacity anode materials based on alloy-type group IV elements always have large volume expansion during lithiation when they are used in lithium-ion batteries. Designing hollow structures is a well-established strategy to accommodate the volume change because of sufficient internal void space. Here we report a facile template-free route to prepare hollow Ge nanospheres without using any templates through a quasi-microemulsion method. Ge nanocrystals are preferably self-assembled along the interface of liquid vesicles between water and tetrahydrofuran, and well-defined hollow architectures of ~50 nm in diameter are formed. Both the wall thickness and hollow interiors can be easily tuned. After subsequent carbon coating via pyrolysis of acetylene, the as-formed Ge@C nanocomposite with hollow interiors exhibits a highly reversible capacity of about 920 mA h g-1 at 200 mA g-1 over 50 cycles, and excellent rate capability. The small size and the high structural integrity of hollow Ge@C structures contribute to the superior lithium-storage performances.High-capacity anode materials based on alloy-type group IV elements always have large volume expansion during lithiation when they are used in lithium-ion batteries. Designing hollow structures is a well-established strategy to accommodate the volume change because of sufficient internal void space. Here we report a facile template-free route to prepare hollow Ge nanospheres without using any templates through a quasi-microemulsion method. Ge nanocrystals are preferably self-assembled along the interface of liquid vesicles between water and tetrahydrofuran, and well-defined hollow architectures of ~50 nm in diameter are formed. Both the wall thickness and hollow interiors can be easily tuned. After subsequent carbon coating via pyrolysis of acetylene, the as-formed Ge@C nanocomposite with hollow interiors exhibits a highly reversible capacity of about 920 mA h g-1 at 200 mA g-1 over 50 cycles, and excellent rate

  4. have a hollow leg

    Institute of Scientific and Technical Information of China (English)

    周立

    2003-01-01

    英语对话 A:We must prevent our family members from getting involved with drugs, really. B:That’s a sure thing.We must make sure that they never involve them- selves with that. A:By the way,does your husband drink a lot? B:Yeah.That’s the only thing that keeps worrying me.And he often boasts that he has a hollow leg and nobody can drink him under the ta- ble.

  5. Anodized dental implant surface

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  6. Anodized aluminum on LDEF

    Science.gov (United States)

    Golden, Johnny L.

    1993-01-01

    A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

  7. Anodizing Aluminum with Frills.

    Science.gov (United States)

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  8. Anodized dental implant surface.

    Science.gov (United States)

    Mishra, Sunil Kumar; Kumar, Muktadar Anand; Chowdhary, Ramesh

    2017-01-01

    Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  9. Extension of spatiotemporal chaos in glow discharge-semiconductor systems

    Energy Technology Data Exchange (ETDEWEB)

    Akhmet, Marat, E-mail: marat@metu.edu.tr; Fen, Mehmet Onur [Department of Mathematics, Middle East Technical University, 06800 Ankara (Turkey); Rafatov, Ismail [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey)

    2014-12-15

    Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528–4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases the potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).].

  10. Comparing investigation of pattern formation in glow and streamer DBD

    Science.gov (United States)

    Li, Ben; Ouyang, Jiting

    2016-11-01

    In this paper, we investigate the behaviors of patterns in dielectric barrier discharge (DBD) in glow and streamer regimes under different operating conditions (driving frequency and voltage) and external electric/magnetic field to explore the similarity and difference of pattern formation. It is found that patterns in both glow and streamer DBDs can be homogenized by decreasing the driving frequency to a low level. But filamentary streamers can still appear at low frequency when the voltage is much higher. With an additional lateral electric field, patterns in both regimes can be homogenized. However, an axial magnetic field makes the glow DBD homogeneous, while the streamer DBD decreases in filamentary size. In both regimes, dynamics and distribution of the space charges, rather than the surface charges, play the predominant role in the formation of DBD patterns. But the surface charges may also play an important role in pattern formation, especially in streamer DBD.

  11. Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

    Science.gov (United States)

    Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

    2016-06-01

    Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

  12. ELECTRON TRANSPORT BEHAVIOURS IN THE NITROGEN DIRECT CURRENT GLOW DISCHARGE

    Institute of Scientific and Technical Information of China (English)

    ZHANG LIAN-ZHU; YU WEI; WANG JIU-LI; HAN LI; FU GUANG-SHENG

    2001-01-01

    A Monte Carlo simulation is presented to describe the electron transport behaviours in the nitrogen direct current glow discharge. The energy and angular distributions of the electrons at different positions of the cathode dark space are calculated; their energy and density distribution features throughout the entire discharge are discussed. The influence of molecular vibrational excitation, typical for electron-molecule collisions, has been studied and the elementary process of active species generation has been illustrated. The simulated results reveal that, in the cathode dark space, the high-energy electrons are mainly forward scattering and behave as a high-energy ‘electron beam'. The sharp increase of the number of secondary electrons plays an important role in producing active species at the interface between the cathode dark space and the negative glow region. The vibrational excitation enhances the energy loss of electrons in the negative glow region.

  13. Recent progress in the application of glow-discharge electrolysis plasma

    National Research Council Canada - National Science Library

    Jie Ren; Mengqi Yao; Wu Yang; Yan Li; Jinzhang Gao

    2014-01-01

    ... produced during the glow-discharge electrolysis (GDE) process. A brief review is already available regarding applications of glow-discharge electrolysis plasma technique in chemistry and environmental science during the past decade...

  14. Rf glow discharge optical emission spectrometry for the analysis of arrays of Ni nanowires in nanoporous alumina and titania membranes

    Energy Technology Data Exchange (ETDEWEB)

    Prida, V.M.; Bordel, N.; Hernando, B. [Depto. Fisica, Universidad Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Navas, D.; Pirota, K.R.; Vazquez, M. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Hernandez-Velez, M. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Depto. Fisica Aplicada, C-XII, Universidad Autonoma Madrid, Cantoblanco, 28049 Madrid (Spain); Menendez, A.; Pereiro, R.; Sanz-Medel, A. [Depto. Quimica Fisica y Analitica, Facultad de Quimica, Julian Claveria 8, 33006 Oviedo (Spain)

    2006-05-15

    Anodic alumina (Al{sub 2}O{sub 3}) and titania (TiO{sub 2}) nanoporous oxide membranes are among the most widely studied self-organized nanopore templates, formed by uniform and well aligned arrays of synthetized nanometric pores or tubes. Here, we perform a comparative study of the depth profiling analysis in self-ordered alumina and titania nanoporous membrane templates by means of the radiofrequency glow discharge coupled to optical emission spectrometry (rf-GD-OES) technique. The densely packed columnar arrays of hexagonally self-ordered nanoporous alumina membranes investigated, with an average inner pore diameter of 35 nm and 105 nm interspacing, give an uniform thickness pore length about more than 5 {mu}m, depending on the anodization time. Meanwhile, the analysis of the anodized titania nanotubes, with an average inner pore diameter of 100 nm and 40 nm wall thickness, shown to be about 300 nm in length. Each type of membranes were also studied in both cases, when the nanopores were empty and after filling with electrodeposited Ni. The direct analysis by rf-GD-OES reveals the ability of this technique to control the quality of these so synthesized nanocomposites formed by electrodeposited Ni nanowires into the alumina and titania nanoporous templates. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Rf glow discharge optical emission spectrometry for the analysis of arrays of Ni nanowires in nanoporous alumina and titania membranes

    Science.gov (United States)

    Prida, V. M.; Navas, D.; Pirota, K. R.; Hernandez-Velez, M.; Menéndez, A.; Bordel, N.; Pereiro, R.; Sanz-Medel, A.; Hernando, B.; Vazquez, M.

    2006-05-01

    Anodic alumina (Al2O3) and titania (TiO2) nanoporous oxide membranes are among the most widely studied self-organized nanopore templates, formed by uniform and well aligned arrays of synthetized nanometric pores or tubes. Here, we perform a comparative study of the depth profiling analysis in self-ordered alumina and titania nanoporous membrane templates by means of the radiofrequency glow discharge coupled to optical emission spectrometry (rf-GD-OES) technique. The densely packed columnar arrays of hexagonally self-ordered nanoporous alumina membranes investigated, with an average inner pore diameter of 35 nm and 105 nm interspacing, give an uniform thickness pore length about more than 5 μm, depending on the anodization time. Meanwhile, the analysis of the anodized titania nanotubes, with an average inner pore diameter of 100 nm and 40 nm wall thickness, shown to be about 300 nm in length. Each type of membranes were also studied in both cases, when the nanopores were empty and after filling with electrodeposited Ni. The direct analysis by rf-GD-OES reveals the ability of this technique to control the quality of these so synthesized nanocomposites formed by electrodeposited Ni nanowires into the alumina and titania nanoporous templates.

  16. Novel light-weight, high-performance anode-supported microtubular solid oxide fuel cells with an active anode functional layer

    Science.gov (United States)

    Liu, Tong; Wang, Yao; Ren, Cong; Fang, Shumin; Mao, Yating; Chen, Fanglin

    2015-10-01

    Influence of the air-gap, the distance from the tube-in-orifice spinneret to the upper surface of the external coagulant bath during the extrusion/phase-inversion process, on the microstructure of nickel - yttria-stabilized zirconia (Ni-YSZ) hollow fibers has been systematically studied. When the air-gap is 0 cm, the obtained Ni-YSZ hollow fiber has a sandwich microstructure. However, when the air-gap is increased to 15 cm, a bi-layer Ni-YSZ hollow fiber consisting of a thin layer with small pores and a thick support with highly porous fingerlike macrovoids has been achieved. The output power density of microtubular solid oxide fuel cells (MT-SOFCs) with a cell configuration of Ni-YSZ/YSZ/YSZ-LSM increases from 594 mW cm-2 for the cells with the Ni-YSZ anode of sandwich microstructure to 832 mW cm-2 for the cells with the Ni-YSZ anode of bi-layer microstructure at 750 °C, implying that to achieve the same output power density, the weight of the cells with the bi-layer anode support can be reduced to 41.5% compared with that of the cells with the sandwich anode support. Thermal-cycling test shows no obvious degradation on the open-circuit-voltage (OCV), indicating that the MT-SOFCs have robust resistance to thermal cycling.

  17. Research of the DC discharge of He-Ne gas mixture in hollow core fiber

    Science.gov (United States)

    Wang, Xinbing; Duan, Lian

    2013-09-01

    Since the first waveguide 0.633 μm He-Ne laser from a 20 cm length of 430 μm glass capillary was reported in 1971, no smaller waveguide gas laser has ever been constructed. Recently as the development of low loss hollow core PBG fiber, it is possible to constract a He-Ne lasers based on hollow-core PBG fibers. For the small diameter of the air hole, it is necessary to do some research to obtain glow discharge in hollow core fibers. In this paper, the experimental research of DC discharge in 200 μm bore diameter hollow core fibers was reported. Stable glow discharge was obained at varioue He-Ne mixtures from 4 Torr to 18 Torr. In order to obtain the plasma parameter of the discharge, the trace gasses of N2 and H2 were added to the He-Ne mixtures, the optical emission spectroscopy of the discharge was recorded by a PI 2750 spectroscopy with a CCD camera. The gas temperature (Tg) could be obtained by matching the simulated rovibronic band of the N2 emission with the observed spectrum in the ultraviolet region. The spectral method was also used to obtained the electron density, which is based on the analysis of the wavelength profile of the 486.13 nm Hβ line, and the electron temperature was obtain by Boltzmann plot methods. Experimental results show that it is very difficult to achieve DC discharge in bore diameter less than 50 μm, and a RF discharge method was proposed. Project supported by the National Natural Science Foundation of China (61078033).

  18. Mercury - the hollow planet

    Science.gov (United States)

    Rothery, D. A.

    2012-04-01

    Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image

  19. Characteristics of sheath-driven tangential flow produced by a low-current DC surface glow discharge plasma actuator

    Science.gov (United States)

    Shin, Jichul; Shajid Rahman, Mohammad

    2014-08-01

    An experimental investigation of low-speed flow actuation at near-atmospheric pressure is presented. The flow actuation is achieved via low-current ( \\lesssim 1.0 mA) continuous or pulsed DC surface glow discharge plasma. The plasma actuator, consisting of two sharp-edged nickel electrodes, produces a tangential flow in a direction from anode to cathode, and is visualized using high-speed schlieren photography. The induced flow velocity estimated via the schlieren images reaches up to 5 m/s in test cases. The actuation capability increases with pressure and electrode gap distances, and the induced flow velocity increases logarithmically with the discharge power. Pulsed DC exhibits slightly improved actuation capability with better directionality. An analytic estimation of induced flow velocity obtained based on ion momentum in the cathode sheath and gas dynamics in one-dimensional flow yields values similar to those measured.

  20. Hysteresis of fluctuation dynamics associated with a fireball in a magnetized glow discharge plasma in a currentless toroidal assembly

    Science.gov (United States)

    Ghosh, Sabuj; Shaw, Pankaj Kumar; Saha, Debajyoti; Janaki, M. S.; Sekar Iyengar, A. N.

    2016-09-01

    Floating potential fluctuations associated with an anode fireball in a glow discharge plasma in the toroidal vacuum vessel of the SINP tokamak are found to exhibit different kinds of oscillations under the action of vertical magnetic field of different strengths. While increasing the vertical magnetic field, the fluctuations have shown transitions as: chaotic oscillation → inverse homoclinic transition → intermittency → chaotic oscillation. However, on decreasing the magnetic field, the fluctuations are seen to follow: chaotic oscillations → homoclinic transition → chaotic oscillation; that is the intermittent feature is not observed. Fireball dynamics is found to be closely related to the magnetic field applied; results of visual inspection with a high speed camera are in close agreement with the fluctuations, and the fireball dynamics is found to be closely related to the transitions. The statistical properties like skewness, kurtosis, and entropy of the fluctuations are also found to exhibit this hysteresis behaviour.

  1. Electrically conductive anodized aluminum coatings

    Science.gov (United States)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  2. Hollow Polyimide Microspheres

    Science.gov (United States)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2001-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 micrometers, a density of about 1 to about 6 pounds/cubic foot and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cubic feet and a compression strength of about 100 to about 1400 pounds/sq inch.

  3. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  4. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  5. Proportional counters aged anode wire recovering using an 80%CF4 + 20%CO2 gas mixture

    CERN Document Server

    Gavrilov, Gennady; Conti, Richard; Fetisov, Andrey; Maysuzenko, Dmitry; Shvecova, Natalia; Vakhtel, Victor

    2011-01-01

    A technique to recover a gas proportional counter having an aged anode wire using a glow discharge in an 80%CF4 + 20%CO2 gas mixture has been developed and tested. Studies of aging effects were carried out under sustained irradiation by an intense 90Sr -source of the straw proportional counters operated with a 60%Ar + 30%CO2 + 10%CF4 gas mixture. Special attention was paid to the aging mechanism of the anode wires. Our experience showed that using a given gas mixture the swelling of the anode wires is a typical mode of aging that leads to degradation of the gas gain. The proposed method of recovery provided a complete restoration of the gas gain and the signal amplitude in the damaged zone of the wire. SEM/XEM analysis confirmed successful cleaning WOx deposits from the wire surface. The application of this method to recover the aged gaseous detectors in real experimental conditions is discussed.

  6. Studying surface glow discharge for application in plasma aerodynamics

    Science.gov (United States)

    Tereshonok, D. V.

    2014-02-01

    Surface glow discharge in nitrogen between two infinite planar electrodes occurring on the same plane has been studied in the framework of a diffusion-drift model. Based on the results of numerical simulations, the plasma structure of this discharge is analyzed and the possibility of using it in plasma aerodynamics is considered.

  7. NEW DEVELOPMENT IN DOUBLE GLOW SURFACE ALLOYING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Several kinds of special alloys are produced on the surfaces of iron and steels by using double glow surface alloying technology. Surface Ni-Cr-Mo-Nb alloy,surface precipitation hardening high speed steel and surface precipitation hardening stainless steel are introduced.

  8. Bubble template synthesis of hollow gold nanoparticles and their applications as theranostic agents

    Science.gov (United States)

    Huang, Chienwen

    Hollow gold nanoparticle with a sub-30nm polycrystalline shell and a 50 nm hollow core has been successfully synthesized through the reduction of sodium gold sulfite by electrochemically evolved hydrogen. Such hollow gold nanoparticles exhibit unique plasmonic properties. They strongly scatter and absorb near infrared light. In this thesis we seek to understand the formation mechanism of hollow gold nanoparticles in this new synthesis process and their plasmonic properties. Also, we explore their biomedical applications as theranostic agents (therapeutic and diagnostic imaging). A lithographically patterned electrode consisting of Ag stripes on a glass substrate was used to investigate the formation process of hollow gold nanoparticles. Ag stripes served as working electrode for electrochemically evolution of hydrogen, and adjacent glass areas provided supporting surface for hydrogen nanobubbles nucleation and growth. Hydrogen nanobubbles served as both templates and reducing agents to trigger the autocatalytic disproportionation reaction of sodium gold sulfite. The effects of applied potential and the additives in the electrolyte have been studied. It has been found that the size and size distribution of hollow gold nanoparticle are directly relative to the applied potential, i.e. the hydrogen evolution rate. It has also been found the addition of Ni2+ ions can greatly improve the size distribution of hollow gold nanoparticles that can be contributed to that the newly electrodeposited nickel metal can enhance the hydrogen evolution efficiency. Another additive, ethylenediamine (EDA) can suppress the autocatalytic reaction of gold sulfite to increase the stability of sodium gold sulfite electrolyte. To capture such electrochemically evolved hydrogen nanobubbles, and subsequently to generate hollow gold nanoparticles in large numbers, alumina membranes were placed on the top of the working electrode. Anodic alumina membrane consists of ~200 nm pores, which provides

  9. Array of surface-confined glow discharges in atmospheric pressure helium: Modes and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Liu, D. X., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Nie, Q. Y.; Li, H. P. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Chen, H. L. [Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Kong, M. G., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2014-05-19

    Array of atmospheric pressure surface discharges confined by a two-dimensional hexagon electrode mesh is studied for its discharge modes and temporal evolution so as to a theoretical underpinning to their growing applications in medicine, aerodynamic control, and environmental remediation. Helium plasma surface-confined by one hexagon-shaped rim electrode is shown to evolve from a Townsend mode to a normal and abnormal glow mode, and its evolution develops from the rim electrodes as six individual microdischarges merging in the middle of the hexagon mesh element. Within one hexagon element, microdischarges remain largely static with the mesh electrode being the instantaneous cathode, but move towards the hexagon center when the electrode is the instantaneous anode. On the entire array electrode surface, plasma ignition is found to beat an unspecific hexagon element and then spreads to ignite surrounding hexagon elements. The spreading of microdischarges is in the form of an expanding circle at a speed of about 3 × 10{sup 4} m/s, and their quenching starts in the location of the initial plasma ignition. Plasma modes influence how input electrical power is used to generate and accelerate electrons and as such the reaction chemistry, whereas plasma dynamics are central to understand and control plasma instabilities. The present study provides an important aspect of plasma physics of the atmospheric surface-confined discharge array and a theoretical underpinning to its future technological innovation.

  10. Glow discharge in low pressure plasma PVD: mathematical model and numerical simulations

    CERN Document Server

    Speranza, A; Meacci, L; Fanfani, S; Borsi, I; Monti, A; 10.1007/s11012-010-9330-z

    2010-01-01

    In this paper we analyze the problem of glow discharge in low pressure plasma in industrial plant, for chambers of different shapes and various working parameters, like pressure and electric potential. The model described is based upon a static approximation of the AC configuration with two electrodes and a drift diffusion approximation for the current density of positive ions and electrons. A detailed discussion of the boundary conditions imposed is given, as well as the full description of the mathematical model. Numerical simulations were performed for a simple 1D model and two different 2D models, corresponding to two different settings of the industrial plant. The simpler case consists of a radially symmetric chamber, with one central electrode (cathode), based upon a DC generator. In this case, the steel chamber acts as the anode. The second model concerns a two dimensional horizontal cut of the most common plant configuration, with two electrodes connected to an AC generator. The case is treated in a "...

  11. Non-local effects in a stratified glow discharge with dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Sukhinin, G I; Fedoseev, A V [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Ramazanov, T S; Amangaliyeva, R Zh; Dosbalayev, M K; Jumabekov, A N [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty, 050012 (Kazakhstan)], E-mail: fedoseev@itp.nsc.ru

    2008-12-21

    The work is aimed at describing non-local effects in the positive column of a low-pressure stratified dc glow discharge in argon with dust particles in a vertical cylindrical discharge tube. Numerical calculations of plasma parameters in the axis of the discharge tube were performed with the help of a hybrid model based on the solution of a non-local Boltzmann equation for electron energy distribution function (EEDF). Axial distributions of optical emission from striations with dust particles were measured experimentally. Negatively charged dust particles in a low-pressure stratified gas discharge should levitate at the anode-side branch of an electric field distribution above its maximum. At the same time the experiments showed that the dust particles levitate at the cathode side of a stratum. This paradox is explained by the fact that in a low-pressure striated discharge the optical emission distribution is displaced relative to the electric field distribution that was shown both by numerical simulations and experimental measurements.

  12. Cobalt silicate hierarchical hollow spheres for lithium-ion batteries

    Science.gov (United States)

    Yang, Jun; Guo, Yuanyuan; Zhang, Yufei; Sun, Chencheng; Yan, Qingyu; Dong, Xiaochen

    2016-09-01

    In this paper, the synthesis of cobalt silicate novel hierarchical hollow spheres via a facile hydrothermal method is presented. With a unique hollow structure, the Co2SiO4 provides a large surface area, which can shorten the lithium ions diffusion length and effectively accommodate the volumetic variation during the lithiation/de-lithiation process. Serving as an anode material in lithium-ion battery application, the Co2SiO4 electrode demonstrates a high reversible specific capacity (first-cycle charge capacity of 948.6 mAh g-1 at 100 mA g-1), a cycling durability (specific capacity of 791.4 mAh g-1 after 100 cycles at 100 mA g-1), and a good rate capability (specific capacity of 349.4 mAh g-1 at 10 A g-1). The results indicate that the cobalt silicate hierarchical hollow sphere holds the potential applications in energy storage electrodes.

  13. Effect of the Hollow Cathode Heat Power on the Performance of an Hall-Effect Thruster

    Institute of Scientific and Technical Information of China (English)

    NING Zhongxi; YU Daren; LI Hong; YAN Guojun

    2009-01-01

    Effect of the hollow cathode heat power on the performance of a Hall-effect thruster is investigated. The variations in the Hall-effect thruster's performance (thrust, specific impulse and anode efficiency) with the hollow cathode heat power was obtained from the analysis of the experimental data. Through an analysis on the coupling relationship between the electrons emitted from the hollow cathode and the environmental plasma, it was found that the heat power would affect the electron emission of the emitter and the space potential of the coupling zone, which would lead to a change in the effective discharge voltage. The experimental data agree well with the results of calculation which can be used to explain the experimental phenomena.

  14. Hollow Nanotubes of N-Doped Carbon on CoS.

    Science.gov (United States)

    Chen, Yuming; Li, Xiaoyan; Park, Kyusung; Zhou, Limin; Huang, Haitao; Mai, Yiu-Wing; Goodenough, John B

    2016-12-19

    Low-cost, single-step synthesis of hollow nanotubes of N-doped carbon deposited on CoS is enabled by the simultaneous use of three functionalities of polyacrylonitrite (PAN) nanofibers: 1) a substrate for loading active materials, 2) a sacrificial template for creating hollow tubular structures, and 3) a precursor for in situ nitrogen doping. The N-doped carbon in hollow tubes of CoS provides a high-capacity anode of long cycle life for a rechargeable Li-ion or Na-ion battery cell that undergoes the conversion reaction 2 A(+) +2 e(-) +CoS →Co+A2 S with A=Li or Na.

  15. Lithium batteries, anodes, and methods of anode fabrication

    KAUST Repository

    Li, Lain-Jong

    2016-12-29

    Prelithiation of a battery anode carried out using controlled lithium metal vapor deposition. Lithium metal can be avoided in the final battery. This prelithiated electrode is used as potential anode for Li- ion or high energy Li-S battery. The prelithiation of lithium metal onto or into the anode reduces hazardous risk, is cost effective, and improves the overall capacity. The battery containing such an anode exhibits remarkably high specific capacity and a long cycle life with excellent reversibility.

  16. Self-Consistent Description of Nitrogen dc Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    傅广生; 王久丽; 于威; 韩理

    2002-01-01

    A self-consistent hybrid Monte Carlo fluid model is presented to describe the nitrogen dc glow discharge. The movement of fast electrons is simulated by the Monte Carlo method while the dynamics of slow electrons and ions is by fluid equations. The spatial features of the charged species and the corresponding electric field throughout the discharge have been calculated, which include the creation rates of ions and slow electrons, densities of the charged species, the electric field and the potential distribution. These closely related results can give a selfconsistent explanation of the discharge characteristics throughout the space of nitrogen dc glow discharge. The calculated ion density is also compared with the corresponding experimental result.

  17. Glow Discharge Induced Hydroxyl Radical Degradation of 2-Naphthylamine

    Institute of Scientific and Technical Information of China (English)

    Lu Quanfang; Yu Jie; Gao Jinzhang; Yang Wu

    2005-01-01

    In an aqueous solution, normal electrolysis at high voltages switches over sponta-neously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, andaqueous electron, as well as several other active species. Hydroxyl radical directly attacks or-ganic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventuallydegraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed byusing an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC)and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (c0 =30 mg.1-1) iscompletely converted within 2h at 30℃ and 600 V by glow discharge electrolysis, and the degra-dation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absenceof ferrous ions and descended in the presence of them.

  18. Inception of Snapover and Gas Induced Glow Discharges

    Science.gov (United States)

    Galofaro, J. T.; Vayner, B. V.; Degroot, W. A.; Ferguson, D. C.; Thomson, C. D.; Dennison, J. R.; Davies, R. E.

    2000-01-01

    Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.

  19. The Use of DC Glow Discharges as Undergraduate Educational Tools

    Energy Technology Data Exchange (ETDEWEB)

    Stephanie A. Wissel and Andrew Zwicker, Jerry Ross, and Sophia Gershman

    2012-10-09

    Plasmas have a beguiling way of getting students excited and interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstrations and advanced investigations of electromagnetism and quantum effects. Our device, based on a direct current (DC) glow discharge tube, allows for a number of experiments into topics such as electrical breakdown, spectroscopy, magnetism, and electron temperature.

  20. Dust particle charge distribution in a stratified glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Sukhinin, Gennady I [Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Lavrentyev Ave., 1, Novosibirsk 630090 (Russian Federation); Fedoseev, Alexander V [Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Lavrentyev Ave., 1, Novosibirsk 630090 (Russian Federation); Ramazanov, Tlekkabul S [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan); Dzhumagulova, Karlygash N [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan); Amangaliyeva, Rauan Zh [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan)

    2007-12-21

    The influence of a highly pronounced non-equilibrium characteristic of the electron energy distribution function in a stratified dc glow discharge on the process of dust particle charging in a complex plasma is taken into account for the first time. The calculated particle charge spatial distribution is essentially non-homogeneous and it can explain the vortex motion of particles at the periphery of a dusty cloud obtained in experiments.

  1. Accurate hierarchical control of hollow crossed NiCo2O4 nanocubes for superior lithium storage

    Science.gov (United States)

    Guo, Hong; Liu, Lixiang; Li, Tingting; Chen, Weiwei; Liu, Jiajia; Guo, Yuanyuan; Guo, Yicheng

    2014-04-01

    An effective approach of simultaneously coordinating etching and precipitation reactions is employed to prepare hollow crossed NiCo2O4 nanocubes as anode materials for lithium-ion batteries. Firstly, amorphous hollow (NiCox)O(OH) nanoboxes form uniformly, and subsequent calcination results in the formation of NiCo2O4 nanocubes that exhibit a stable reversible capacity of 1160 mA h g-1 at constant current density of 200 mA g-1 with capacity retention of over 91.1% after 200 cycles. The unique hollow structure can shorten the Li-ion diffusion path, which benefits the rate of performance. Furthermore, the hollow structure offers a sufficient void space to alleviate the mechanical stress caused by volume change. Additionally, the multi-element characteristics of active materials allow the volume change to take place in a stepwise manner. Therefore, hollow crossed NiCo2O4 nanocube electrodes exhibit excellent electrochemical performance. This method is simple and of low cost, which may open a new avenue for fast synthesis of hollow crossed structural nano-functional materials for energy storage, catalysts, sensors and other new applications.An effective approach of simultaneously coordinating etching and precipitation reactions is employed to prepare hollow crossed NiCo2O4 nanocubes as anode materials for lithium-ion batteries. Firstly, amorphous hollow (NiCox)O(OH) nanoboxes form uniformly, and subsequent calcination results in the formation of NiCo2O4 nanocubes that exhibit a stable reversible capacity of 1160 mA h g-1 at constant current density of 200 mA g-1 with capacity retention of over 91.1% after 200 cycles. The unique hollow structure can shorten the Li-ion diffusion path, which benefits the rate of performance. Furthermore, the hollow structure offers a sufficient void space to alleviate the mechanical stress caused by volume change. Additionally, the multi-element characteristics of active materials allow the volume change to take place in a stepwise manner

  2. Method of computerized glow curve deconvolution for analysing thermoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, T [Division of General Education, Ashikaga Institute of Technology, Omae-cho 268-1, Ashikaga, Tochigi 326-8558 (Japan); Gartia, R K [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India)

    2003-11-07

    The conventional worldwide accepted method of computerized glow curve deconvolution based on the general order kinetics formalism has two fatal defects in systems where the trapping levels (two or more) have non-zero retrapping probability. The first one is ignoring the thermal connectivity between thermoluminescence (TL) peaks. This arises from the fact that under such a situation electrons trapped at one trapping level, once activated, can be retrapped in another thermally connected level via the conduction band during the recording of the glow curve. The other is the impossibility of obtaining a global minimum, in fitting the experimental TL with the theoretical one with existing techniques. This paper aims to provide answers to these defects. The first one can be overcome by resorting to rigorous analysis using appropriate mathematical rate equations describing the flow of charge carriers. Though the second defect cannot be overcome completely, one can obtain a reasonable fit, which may not be unique. The algorithm is tested for synthetic as well as experimental glow curves.

  3. Sputtered-deposited thin brass films in a modified glow discharge Grimm-type source

    Science.gov (United States)

    Grais, K. I.; Eid, M. A.; Tawfik, N. L.; Abd-El-Aal, M. S.; Shaltout, A. A.

    2006-08-01

    Modification of the non-assisted gas flow-line across the target surface in a Grimm-type glow discharge source is described. The new flow line permits the gas to flow through a cylindrical annular space ending with a disc-space annular gap, facing the target surface. This configuration would cause directed jet assisted gas flow rays to impinge on infinite points across the cathode surface. Improvement has been achieved in the V-I characteristics where Δ V/Δ I increases from 1.8 to 3.5 V/mA. The sputtering as well as simultaneous deposition rates, have been increased by a factor of 16 and 17 respectively. These roll over with increasing sputtering time, their maximum values at a characteristic time, toc of 21 min. The toc value was constant for different operating parameters provided that the source geometry assembly is kept fixed. The presence of a glass substrate in the anode cavity has, apparently, no effect on the obtained data. Improvements have also been achieved in the crater profile, characterized by an approximately flat crater bottom with nearly vertical walls, and less re-deposited particles on the crater depth and edge. Fixing the distance Z of the substrate from target surface, along the cell axis, and varying the deposition time from 1 to 30 min, a sequence of changes in the deposited film were observed by X-ray diffraction and energy dispersion X-ray (EDX). These changes start with an amorphous structure, followed by the appearance of Cu and Zn crystallites and a probable deposition of Cu{5}Zn{8} clusters. The profile of the number of sputtered particles at different Z values is characterized by a number of peaks and troughs. This behavior has been explained by the occurrence of local cluster-dissociation and formation, by different collision processes. The improvements achieved by the application of the present jet assisted gas flow can be of value in the analytical application of this type of glow discharge.

  4. Anodes sliced with ions

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    2006-01-01

    A detailed image of a complex fuel-cell anode structure, obtained through ion-beam milling, SEM imaging and advanced digital reconstruction, yields an accurate description of the three-dimensional structure, and enables correct prediction of the electrode's properties

  5. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  6. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  7. Effect of the interaction among traps on the shape of thermoluminescence glow curves

    Energy Technology Data Exchange (ETDEWEB)

    Marcazzo, J. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Santiago, M. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina) and Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina)]. E-mail: msantiag@exa.unicen.edu.ar; Spano, F. [Autoridad Regulatoria Nuclear, Av. del Libertador 8250, 1429 Buenos Aires (Argentina); Lester, M. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Ortega, F. [Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, Av. del Valle 5737, 7400 Olavarria (Argentina); Molina, P. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Caselli, E. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), calle 526 entre 10 y 11, 1900 La Plata (Argentina)

    2007-09-15

    The effect of the interaction among traps on the structure of thermoluminescence glow curves has been investigated by generating numerically simulated glow curves for a wide range of trap parameters. The results reported in this paper provide useful insights which assist in the analysis of experimental glow curves. The most important result shows that it is incorrect to assume beforehand that each peak is related to a specific trapping state. The validity of the quasiequilibrium approximation is briefly discussed.

  8. Movable anode x-ray source with enhanced anode cooling

    Science.gov (United States)

    Bird, C.R.; Rockett, P.D.

    1987-08-04

    An x-ray source is disclosed having a cathode and a disc-shaped anode with a peripheral surface at constant radius from the anode axis opposed to the cathode. The anode has stub axle sections rotatably carried in heat conducting bearing plates which are mounted by thermoelectric coolers to bellows which normally bias the bearing plates to a retracted position spaced from opposing anode side faces. The bellows cooperate with the x-ray source mounting structure for forming closed passages for heat transport fluid. Flow of such fluid under pressure expands the bellows and brings the bearing plates into heat conducting contact with the anode side faces. A worm gear is mounted on a shaft and engages serrations in the anode periphery for rotating the anode when flow of coolant is terminated between x-ray emission events. 5 figs.

  9. A glow curve analyzer (GCA) for routine analysis of personnel thermoluminescent dosemeter results

    Energy Technology Data Exchange (ETDEWEB)

    Chase, W.J. [Health Physics Department, Ontario Power Generation, Whitby, Ont. (Canada)], E-mail: john.chase@opg.com; Bezaire, M.D. [Department of Applied Health Sciences, University of Waterloo, Waterloo, Ont. (Canada); Vanderzwet, F.P. [Bruce Power, P.O. Box 1540, Building B13, Tiverton, Ont., N0G 2T0 (Canada); Taylor, C.E. [Health Physics Department, Ontario Power Generation, Whitby, Ont. (Canada)

    2008-02-15

    A glow curve analyzer (GCA) spreadsheet has been developed using Microsoft Excel to perform glow curve analysis on thermoluminescent dosimeter (TLD) data from a personnel dosimetry system. The TLD data come from cards with four LiF:Mg,Ti chips that have been annealed and therefore have a simple glow peak structure. GCA removes spikes in the glow curve data, and then smoothes it. After select start and end points for the glow peak, it fits a Boltzmann function to represent the glow curve signal background under the glow peak. The Boltzmann function is subtracted and two Weibull curves are fit to the remaining net signal between the start and end points. The first Weibull curve is fit to peak 5, and the second one to any small remaining contribution from peaks 3 and 4 or from contaminants. The sum of the two Weibull curves is the glow curve signal result. GCA provides rapid review and correction of all glow curves, improving the quality of the results and reducing the time required for complete processing of official dose results.

  10. Glow curves and the emission of flux grown BaFCl:Gd crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Hari Babu, V. (Osmania Univ., Hyderabad (India). Dept. of Physics)

    1984-03-16

    Thermoluminescence output of the BaFCl is found to be enhanced enormously when it is doped with gadolinium. An incorporation of gadolinium in BaFCl produces additional glow peaks at 455 and 560 K, an optical absorption band at 660 nm, and glow emission bands at 315 and 450 nm. The 315 nm emission band is the characteristic emission of the gadolinium impurity. Since similar emission spectra are obtained for different glow peaks, they are attributed to the luminescent centers caused by the gadolinium impurity in the lattice. The trap depth and frequency factor of additional glow peaks are calculated employing different methods.

  11. Runaway Electron Preionized Diffuse Discharge and Its Impact on Plane Anode

    Science.gov (United States)

    Tarasenko, Victor; Erofeev, Michael; Ripenko, Vasilii; Shulepov, Mikhail; Baksht, Evgenii; National Research Tomsk Polytechnic University Collaboration; Institute of High Current Electronics Collaboration

    2016-09-01

    The spatial structure of a runaway electrons preionized diffuse discharge (REP DD) in nonuniform electric field and the influence of its plasma on the surface of a plane anode have been studied. In our experiments, we used a NPG-18/3500N high-voltage generator. The incident voltage had negative polarity, amplitude of 20 kV, and FWHM of 6 ns; the discharge current was up to 200 A. The discharge plasma was formed in nitrogen by applying high voltage pulses to the interelectrode gap which was varied between 2 and 9 mm. Under such conditions, the specific input power reached up to 10 MW/cm3. It is established that diffuse channel is the initial stage of the discharge radiation; then anode spot, channel with high glow intensity based on the anode spot and spark channel are consecutively formed. Spark formation finished within 10-15 ns after the onset of the discharge. Microstructure of spark and diffuse channels with anode spot autograph have been detected. The traces of such discharge represents itself an aggregation of up to 100 microcraters with dimeters of 5-100 micrometers. It was also shown that diffuse discharge does not leave erosive action on an anode surface or on its carbon cover. This work was supported by the Russian Science Foundation under the Grant Number 14-29-00052.

  12. Mechanical and Abrasive Wear Properties of Anodic Oxide Layers Formed on Aluminium

    Institute of Scientific and Technical Information of China (English)

    W.Bensalah; K.Elleuch; M.Feki; M.Wery; H.F.Ayedi

    2009-01-01

    Aluminium oxide coatings were formed on aluminium substrates in oxalic acid-sulphuric acid bath. Abrasion tests of the obtained anodic layers were carried out on a pin-on-disc machine in accordance with the ISO/DP 825 specifications. The Vickers microhardness, D (HV0.2). and the abrasion weight loss, Wa (mg) were measured. Influence of oxalic acid concentration (Cox), bath temperature (T) and anodic current density (J) on D and Wa has been examined, and the sulphuric acid concentration (Caul) was maintained at 160 g.L-1. It was found that high microhardness and abrasive wear resistance of oxide layers were produced under low temperatures and high current densities with the addition of oxalic acid. The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), optical microscopy and glow-discharge optical emission spectroscopy (GDOES). It was found that the chemistry of the anodizing electrolyte, temperature, and current density are the controlling factors of the mechanical properties of the anodic oxide layer.

  13. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  14. Large Scale Modelling of Glow Discharges or Non - Plasmas

    Science.gov (United States)

    Shankar, Sadasivan

    The Electron Velocity Distribution Function (EVDF) in the cathode fall of a DC helium glow discharge was evaluated from a numerical solution of the Boltzmann Transport Equation(BTE). The numerical technique was based on a Petrov-Galerkin technique and a unique combination of streamline upwinding with self -consistent feedback-based shock-capturing. EVDF for the cathode fall was solved at 1 Torr, as a function of position x, axial velocity v_{rm x}, radial velocity v_{rm r}, and time t. The electron-neutral collisions consisted of elastic, excitation, and ionization processes. The algorithm was optimized and vectorized to speed execution by more than a factor of 10 on CRAY-XMP. Efficient storage schemes were used to save the memory allocation required by the algorithm. The analysis of the solution of BTE was done in terms of the 8-moments that were evaluated. Higher moments were found necessary to study the momentum and energy fluxes. The time and length scales were estimated and used as a basis for the characterization of DC glow discharges. Based on an exhaustive study of Knudsen numbers, it was observed that the electrons in the cathode fall were in the transition or Boltzmann regime. The shortest relaxation time was the momentum relaxation and the longest times were the ionization and energy relaxation times. The other times in the processes were that for plasma reaction, diffusion, convection, transit, entropy relaxation, and that for mean free flight between the collisions. Different models were classified based on the moments, time scales, and length scales in their applicability to glow discharges. These consisted of BTE with different number af phase and configuration dimensions, Bhatnagar-Gross-Krook equation, moment equations (e.g. Drift-Diffusion, Drift-Diffusion-Inertia), and spherical harmonic expansions.

  15. Ideal anodization of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Yamani, Z.; Thompson, W.H.; AbuHassan, L.; Nayfeh, M.H. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States)

    1997-06-01

    Silicon has been anodized such that the porous layer is passivated with a homogeneous stretching phase by incorporating H{sub 2}O{sub 2} in the anodization mixture. Fourier transform infrared spectroscopy measurements show that the Si{endash}H stretching mode oriented perpendicular to the surface at {approximately}2100cm{sup {minus}1} dominates the spectrum with negligible contribution from the bending modes in the 600{endash}900cm{sup {minus}1} region. Material analysis using Auger electron spectroscopy shows that the samples have very little impurities, and that the luminescent layer is very thin (5{endash}10 nm). Scanning electron microscopy shows that the surface is smoother with features smaller than those of conventional samples. {copyright} {ital 1997 American Institute of Physics.}

  16. Quartz antenna with hollow conductor

    Science.gov (United States)

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  17. Hollow waveguide for urology treatment

    Science.gov (United States)

    Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.

    2010-02-01

    The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.

  18. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A.QAYYUM; M.A.NAVEED; S.ZEB; G.MURTAZA; M.ZAKAULLAH

    2007-01-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis.The treated samples were analysed by X-ray diffraction(XRD)to explore the changes induced in the crystallographic structure.The XRD pattern confirmed the formation of an expanded austenite phase(γN)owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice.A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth(μm).The results showed clear evidence of surface changes with substantial increase in surface hardness.

  19. ULTRAVIOLET INDUCED MOTION OF A FLUORESCENT DUST CLOUD IN AN ARGON DIRECT CURRENT GLOW DISCHARGE PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Hvasta, M.G.; and Zwicker, A.

    2008-01-01

    Dusty plasmas consist of electrons, ions, neutrals and nm-μm sized particles commonly referred to as dust. In man-made plasmas this dust may represent impurities in a tokamak or plasma etching processing. In astrophysical plasmas this dust forms structures such as planetary rings and comet tails. To study dusty plasma dynamics an experiment was designed in which a 3:1 silica (<5 μm diameter) and fl uorescent dust mixture was added to an argon DC glow discharge plasma and exposed to UV radiation. This fl uorescent lighting technique offers an advantage over laser scattering (which only allows two-dimensional slices of the cloud to be observed) and is simpler than scanning mirror techniques or particle image velocimetry. Under typical parameters (P=150 mTorr, V anode= 100 V, Vcathode= -400 V, Itotal < 2mA) when the cloud is exposed to the UV light (100W, λ = 365 nm) the mixture fl uoresces, moves ~2mm towards the light source and begins rotating in a clockwise manner (as seen from the cathode). By calibrating a UV lamp and adjusting the relative intensity of the UV with a variable transformer it was found that both translational and rotational velocities are a function of UV intensity. Additionally, it was determined that bulk cloud rotation is not seen when the dust tray is not grounded while bulk translation is. This ongoing experiment represents a novel way to control contamination in man-made plasmas and a path to a better understanding of UV-bathed plasma systems in space..

  20. 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.

  1. Cold starting of fluorescent lamps - part II: experiments on glow times and electrode damaging

    Science.gov (United States)

    Langer, Reinhard; Paul, Irina; Hilscher, Achim; Horn, Siegfried; Tidecks, Reinhard

    2017-01-01

    In the present work we present experiments on cold start and the resulting electrode damaging (reducing lamp life) of AC driven fluorescent lamps. The crucial parameter is the glow time, determined from time resolved measurements of lamp voltage and current. The relation between the energy consumed during glow phase and the glow time is studied. It turns out that there is no common threshold of energy until the glow-to-arc transition takes place, but strong energy input into the lamp yields short glow times. The transient behaviour from the glow to the arc regime is investigated and the stable operation points of the arc discharge are determined, yielding an arc discharge voltage-current characteristics of the lamp type investigated. The electrode damage is investigated as a function of the open source voltage and the ballast resistance. Subsequent cold starts lead to an increase of the glow time due to electrode damaging, i.e., the electrode damage accumulates. Different regeneration procedures and their effectiveness are compared. Regeneration burning turns out to be more effective than heating up the electrode. A criterion for avoiding high electrode damage is obtained, indicating that the average power during glow time should exceed 20 W.

  2. Assessing the Warm Glow Effect in Contingent Valuations for Public Libraries

    Science.gov (United States)

    Lee, Soon-Jae; Chung, Hye-Kyung; Jung, Eun-Joo

    2010-01-01

    This article aims to present evidence of the warm glow effect in a public library setting. More specifically, it tests whether individual respondents with different values for the warm glow component report different values for their willingness to pay (WTP). The data come from a contingent valuation survey conducted on randomly selected citizens…

  3. Glow experiment documentation of OMS/RCS pods and vertical stabilizer

    Science.gov (United States)

    1982-01-01

    Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemoluminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera used to record glow on vertical tail and OMS pods.

  4. Glow experiment documentation of OMS/RCS pod and vertical stabilizer

    Science.gov (United States)

    1982-01-01

    Glow experiment documentation of one of the orbital maneuvering system (OMS) reaction control system (RCS) pods and a portion of the vertical stabilizer shows chemoluminescent effectresulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. The Image Intensifier on NIKON 35mm camera was used to record the glow.

  5. Assessing the Warm Glow Effect in Contingent Valuations for Public Libraries

    Science.gov (United States)

    Lee, Soon-Jae; Chung, Hye-Kyung; Jung, Eun-Joo

    2010-01-01

    This article aims to present evidence of the warm glow effect in a public library setting. More specifically, it tests whether individual respondents with different values for the warm glow component report different values for their willingness to pay (WTP). The data come from a contingent valuation survey conducted on randomly selected citizens…

  6. Numerical analysis of thermoluminescence glow curves; Analisis numerico de las cruvas de termoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Ros, J. M.; Delgado, A.

    1989-07-01

    This report presents a method for the numerical analysis of complex thermoluminescence glow curves resolving the individual glow peak components. The method employs first order kinetics analytical expressions and is based In a Marquart-Levenberg minimization procedure. A simplified version of this method for thermoluminescence dosimetry (TLD) is also described and specifically developed to operate whit Lithium Fluoride TLD-100. (Author). 36 refs.

  7. Study of the Discharge Mode in Micro-Hollow Cathode

    Institute of Scientific and Technical Information of China (English)

    HE Feng; HE Shoujie; ZHAO Xiaofei; GUO Bingang; OUYANG Jiting

    2012-01-01

    In this study, micro-hollow cathode discharge (MHCD) is investigated by a fluid model with drift-diffusion approximation. The MHC device is a cathode/dielectric/anode sandwich structure with one hole of a diameter D=200 um. The gas is a Ne/Xe mixture at a pressure p=50-500 Torr. The evolutions of the discharge show that there are two different discharge modes. At larger pD the discharge plasma and high density excited species expand along the cathode surface and, a ringed discharge mode is formed. At smaller pD, the discharge plasma and the excited species expand along the axis of the cathode aperture to form a columnar discharge.

  8. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  9. Application of computerized glow curve deconvolution to determine the spectroscopy of traps in colorless microcline

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, B. Arunkumar [Department of Radiotherapy, RIMS, Lamphel, Imphal 795004, Manipur (India)], E-mail: arunsb2000@yahoo.co.uk; Singh, A. Nabachandra [Department of Physics, Thoubal College, Thoubal 795138, Manipur (India); Singh, S. Nabadwip [Department of Physics, Kumbi College, Kumbi 795133, Manipur (India); Singh, O. Binoykumar [Department of Physics, Y.K. College, Wangjing 795148, Manipur (India)

    2009-01-15

    Kinetic parameters of glow peaks (as many as 14 in the range of 75-575 deg. C) of colorless microcline have been successfully achieved to a high degree of certainty by resorting to computerized glow curve deconvolution (CGCD) in the framework of kinetics formalism. The second derivative plot of the experimental glow curve is used to locate the hidden glow peaks. The criteria to accept the goodness of fit between the experimental glow curve and the numerically generated best fit curve is judged by statistical test namely, {chi}{sup 2}-test. As a cross check, figure of merit (FOM) is also evaluated. The kinetic parameters of the higher temperature trap electrons of colorless microcline are determined by using lower heating rates.

  10. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  11. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  12. Research on the Plasma Anemometer Based on AC Glow Discharge

    Directory of Open Access Journals (Sweden)

    Bing Yu

    2017-01-01

    Full Text Available A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

  13. COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS

    Energy Technology Data Exchange (ETDEWEB)

    CZECHOWICZ, DG; CASTILLO, ER; NIKROO, A

    2002-04-01

    OAK A271 COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS. An investigation of the chemical composition and structure of strong glow discharge (GDP) polymer shells made for cryogenic experiments at OMEGA is described. The investigation was carried out using combustion and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The strongest coatings were observed to have the lowest hydrogen content or hydrogen/carbon H/C ratio, whereas the weakest coatings had the highest hydrogen content or H/C ratio. Chemical composition results from combustion were used to complement FTIR analysis to determine the relative hydrogen content of as-fabricated coatings. Good agreement was observed between composition results obtained from combustion and FTIR analysis. FTIR analysis of coating structures showed the strongest coatings to have less terminal methyl groups and a more double bond or olefinic structure. Strong GDP coatings that were aged in air react more with oxygen and moisture than standard GDP coatings. In addition to a more olefinic structure, there may also be more free-radial sites present in strong GDP coatings, which leads to greater oxygen uptake.

  14. Multiple solutions in the theory of dc glow discharges

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, P G C; Benilov, M S; Faria, M J [Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

    2010-04-15

    Multiple steady-state solutions existing in the theory of dc glow discharges are computed for the first time. The simulations are performed in 2D in the framework of the simplest self-consistent model, which accounts for a single ion species and employs the drift-diffusion approximation. Solutions describing up to nine different modes were found in the case where losses of the ions and the electrons due to diffusion to the wall were neglected. One mode is 1D, exists at all values of the discharge current, and represents in essence the well-known solution of von Engel and Steenbeck. The other eight modes are axially symmetric, exist in limited ranges of the discharge current, and are associated with different patterns of current spots on the cathode. The mode with a spot at the centre of the cathode exhibits a well pronounced effect of normal current density. Account of diffusion losses affects the solutions dramatically: the number of solutions is reduced, a mode appears that exists at all discharge currents and comprises the Townsend, subnormal, normal and abnormal discharges. The solutions that exist in limited current ranges describe patterns, and these patterns seem to represent axially symmetric analogues of the 3D patterns observed in dc glow microdischarges in xenon.

  15. Towards a reduced chemistry module of a He-Ar-Cu hollow cathode discharge

    Science.gov (United States)

    Mihailova, D.; van Dijk, J.; Grozeva, M.; Degrez, G.; van der Mullen, J. J. A. M.

    2011-05-01

    This study is aimed at finding a reduced chemistry module for a hollow cathode discharge (HCD) excited in a He-Ar-Cu mixture. This enables us to construct lean and reliable models that can be used as a part of the design tool of HCDs. To this end estimative calculations and numerical simulations are performed under optimal conditions for lasing. An analysis of the species behaviour and reactions is made and as a result the model is simplified by means of reducing the number of species and reactions. The consequences of these reductions are justified by comparing the results of the simplified models with those of a more complete one. This study delivers a model that is chemically lean and thus, much less time consuming. It can be used in optimization studies to find the optimum in the plasma control parameter set of HCDs. The technique developed in this study for HCDs can be applied to glow discharges in general.

  16. Degradation of Remazol Red in batik dye waste water by contact glow discharge electrolysis method using NaOH and NaCl electrolytes

    Science.gov (United States)

    Saksono, Nelson; Putri, Dita Amelia; Suminar, Dian Ratna

    2017-03-01

    Contact Glow Discharge Electrolysis (CGDE) method is one of Plasma Electrolysis technology which has been approved to degrade organic waste water because it is very productive in producing hydroxyl radical. This study aims to degrade Remazol Red by CGDE method and evaluate important parameters that have influent in degradation process of Remazol Red in Batik dye waste water in batch system. The kind of electrolyte (acid and base) and the addition of metal ion such as Fe2+ have affected Remazol Red degradation percentage. Ultraviolet-Visible (UV-Vis) absorption spectra were used to monitor the degradation process. The result of study showed that percentage degradation was 99.97% which obtained by using NaCl 0.02 M with addition Fe2+ 20 ppm, applied voltage 700 volt, anode depth 0.5 cm, initial concentration of Remazol Red 250 ppm and the temperature of solutions was maintained 50-60 ˚C.

  17. Application of contact glow discharge electrolysis method for degradation of batik dye waste Remazol Red by the addition of Fe2+ ion

    Science.gov (United States)

    Saksono, Nelson; Puspita, Indah; Sukreni, Tulus

    2017-03-01

    Contact Glow Discharge Electrolysis (CGDE) has been shown to degrade much weight organic compounds such as dyes because the production of hydroxil radical (•OH) is excess. This research aims to degrade batik dye waste Remazol Red, using CGDE method with the addition of Fe2+ ion. The addition of iron salt compounds has proven to increase process efficiency. Dye degradation is known by measure its absorbances with Spectrophotometer UV-Vis. The result of study showed that percentage degradation was 99.92% in 20 minutes which obtained by using Na2SO4 0.01 M, with addition FeSO4 0,1 gram, applied voltage 860 volt, and 1 wolfram anode 5 mm depth.

  18. Thin flexible intercalation anodes

    Energy Technology Data Exchange (ETDEWEB)

    Levy, S.C.; Cieslak, W.R.; Klassen, S.E.; Lagasse, R.R.

    1994-10-01

    Poly(acrylonitrile) fibers have been pyrolyzed under various conditions to form flexible carbon yarns capable of intercalating lithium ions. These fibers have also been formed into both woven and non woven cloths. Potentiostatic, potentiodynamic and galvanostatic tests have been conducted with these materials in several electrolytes. In some tests, a potential hold was used after each constant current charge and discharge. These tests have shown some of these flexible materials to reversibly intercalate lithium ions to levels that are suitable for use as a practical battery anode.

  19. Anodic bonded graphene

    Science.gov (United States)

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Marangolo, Massimiliano; Lacaze, Emanuelle; Gohler, Roger; Escoffier, Walter; Poumirol, Jean-Marie; Shukla, Abhay

    2010-09-01

    We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 µm lateral dimensions. This method is also extensible to other layered materials. We discuss some detailed aspects of the fabrication and results from Raman spectroscopy, local probe microscopy and transport measurements on these samples.

  20. Anodic bonded graphene

    Energy Technology Data Exchange (ETDEWEB)

    Balan, Adrian; Kumar, Rakesh; Boukhicha, Mohamed; Beyssac, Olivier; Bouillard, Jean-Claude; Taverna, Dario; Sacks, William; Shukla, Abhay [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7590, Institut de Mineralogie et de Physique des Milieux Condenses, 140 rue de Lourmel, Paris, F-75015 France (France); Marangolo, Massimiliano; Lacaze, Emanuelle; Gohler, Roger [Universite Pierre et Marie Curie-Paris 6, CNRS-UMR7588, Institut des Nanosciences de Paris, 140 rue de Lourmel, Paris, F-75015 France (France); Escoffier, Walter; Poumirol, Jean-Marie, E-mail: abhay.shukla@upmc.f [Laboratoire National des Champs Magnetiques Intenses, INSA UPS CNRS, UPR 3228, Universite de Toulouse, 143 avenue de Rangueil, 31400 Toulouse (France)

    2010-09-22

    We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, a graphite precursor in flake form is bonded to a glass substrate with the help of an electrostatic field and then cleaved off to leave few layer graphene on the substrate. Now that several methods are available for producing graphene, the relevance of our method is in its simplicity and practicality for producing graphene samples of about 100 {mu}m lateral dimensions. This method is also extensible to other layered materials. We discuss some detailed aspects of the fabrication and results from Raman spectroscopy, local probe microscopy and transport measurements on these samples.

  1. Nitrogen-Doped Hollow Carbon Nanospheres for High-Performance Li-Ion Batteries.

    Science.gov (United States)

    Yang, Yufen; Jin, Song; Zhang, Zhen; Du, Zhenzhen; Liu, Huarong; Yang, Jia; Xu, Hangxun; Ji, Hengxing

    2017-04-26

    N-doped carbon materials is of particular attraction for anodes of lithium-ion batteries (LIBs) because of their high surface areas, superior electrical conductivity, and excellent mechanical strength, which can store energy by adsorption/desorption of Li(+) at the interfaces between the electrolyte and electrode. By directly carbonization of zeolitic imidazolate framework-8 nanospheres synthesized by an emulsion-based interfacial reaction, we obtained N-doped hollow carbon nanospheres with tunable shell thickness (20 nm to solid sphere) and different N dopant concentrations (3.9 to 21.7 at %). The optimized anode material possessed a shell thickness of 20 nm and contained 16.6 at % N dopants that were predominately pyridinic and pyrrolic. The anode delivered a specific capacity of 2053 mA h g(-1) at 100 mA g(-1) and 879 mA h g(-1) at 5 A g(-1) for 1000 cycles, implying a superior cycling stability. The improved electrochemical performance can be ascribed to (1) the Li(+) adsorption dominated energy storage mechanism prevents the volume change of the electrode materials, (2) the hollow nanostructure assembled by the nanometer-sized primary particles prevents the agglomeration of the nanoparticles and favors for Li(+) diffusion, (3) the optimized N dopant concentration and configuration facilitate the adsorption of Li(+); and (4) the graphitic carbon nanostructure ensures a good electrical conductivity.

  2. Porous nano-structured Co3O4 anode materials generated from coordination-driven self-assembled aggregates for advanced lithium ion batteries.

    Science.gov (United States)

    Ge, Danhua; Geng, Hongbo; Wang, Jiaqing; Zheng, Junwei; Pan, Yue; Cao, Xueqin; Gu, Hongwei

    2014-08-21

    A simple and scalable coordination-derived method for the synthesis of porous Co3O4 hollow nanospheres is described here. The initially formed coordination-driven self-assembled aggregates (CDSAAs) could act as the precursor followed by calcination treatment. Then the porous hollow Co3O4 nanospheres are obtained, in which the primary Co3O4 nanoparticles are inter-dispersed. When the nanospheres are used as anode materials for lithium storage, they show excellent coulombic efficiency, high lithium storage capacity and superior cycling performance. In view of the facile synthesis and excellent electrochemical performance obtained, this protocol to fabricate special porous hollow frameworks could be further extended to other metal oxides and is expected to improve the practicality of superior cycle life anode materials with large volume excursions for the development of the next generation of LIBs.

  3. Mesoporous Silicon-Based Anodes

    Science.gov (United States)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  4. Modeling the breakdown and glow phases during ignition of HID lamps

    Energy Technology Data Exchange (ETDEWEB)

    Liland, K.B.; Peres, I.; Pitchford, L.C.; Boeuf, J.P. [Univ. Paul Sabatier, Toulouse (France)

    1996-12-31

    HID lamps are often ignited by one or more short, high voltage pulses (trigger pulses) superimposed on the low frequency, generator voltage. The authors have developed a self-consistent, fluid model of transient glow discharges to study the breakdown and glow phases in HID lamps from the time of the application of the trigger pulse(s) to the time when there is a fully-developed, quasi-steady state glow discharge. The transition to the thermionic arc is not considered here. Using this model they have investigated the influence of the height, width and number of trigger pulses on the generator voltage required to achieve a steady-state glow discharge. The model used is one-dimensional, and the fundamental variables are the charged particle densities and the potential as functions of distance between the electrodes and time. The minimum voltage needed to initiate a glow discharge, V{sub g}, decreases with increasing current during the trigger pulse and reaches a minimum which is a few volts above the steady-state glow voltage. Results in discharges in argon and argon/mercury mixtures will be presented showing the dependence of V{sub g} on the trigger pulse and on other discharge conditions (gas mixture, external circuit, ...). The calculated, steady-state glow current-voltage characteristic will also be presented.

  5. Hollow Carbon Nanofiber-Encapsulated Sulfur Cathodes for High Specific Capacity Rechargeable Lithium Batteries

    KAUST Repository

    Zheng, Guangyuan

    2011-10-12

    Sulfur has a high specific capacity of 1673 mAh/g as lithium battery cathodes, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a hollow carbon nanofiber-encapsulated sulfur cathode for effective trapping of polysulfides and demonstrate experimentally high specific capacity and excellent electrochemical cycling of the cells. The hollow carbon nanofiber arrays were fabricated using anodic aluminum oxide (AAO) templates, through thermal carbonization of polystyrene. The AAO template also facilitates sulfur infusion into the hollow fibers and prevents sulfur from coating onto the exterior carbon wall. The high aspect ratio of the carbon nanofibers provides an ideal structure for trapping polysulfides, and the thin carbon wall allows rapid transport of lithium ions. The small dimension of these nanofibers provides a large surface area per unit mass for Li2S deposition during cycling and reduces pulverization of electrode materials due to volumetric expansion. A high specific capacity of about 730 mAh/g was observed at C/5 rate after 150 cycles of charge/discharge. The introduction of LiNO3 additive to the electrolyte was shown to improve the Coulombic efficiency to over 99% at C/5. The results show that the hollow carbon nanofiber-encapsulated sulfur structure could be a promising cathode design for rechargeable Li/S batteries with high specific energy. © 2011 American Chemical Society.

  6. 78 FR 60271 - Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of Application for Transfer of...

    Science.gov (United States)

    2013-10-01

    ... Federal Energy Regulatory Commission Hollow Dam Power Company; Ampersand Hollow Dam Hydro, LLC; Notice of..., Hollow Dam Power Company (transferor) and Ampersand Hollow Dam Hydro, LLC (transferee) filed an application for transfer of license for the Hollow Dam Project, FERC No. 6972, located on the West Branch...

  7. Evaluation of a pulsed glow discharge time-of-flight mass spectrometer as a detector for gas chromatography and the influence of the glow discharge source parameters on the information volume in chemical speciation analysis.

    Science.gov (United States)

    Fliegel, Daniel; Fuhrer, Katrin; Gonin, Marc; Günther, Detlef

    2006-09-01

    The figures of merit of a pulsed glow discharge time-of-flight mass spectrometer (GD-TOFMS) as a detector for gas chromatography (GC) analysis were evaluated. The mass resolution for the GD-TOFMS was determined on FWHM in the high mass range (208Pb+) as high as 5,500. Precision of 400 subsequent analyses was calculated on 63Cu+ to be better than 1% RSD with no significant drift over the time of the analysis. Isotope precision based on the 63Cu+/65Cu+ ratio over 400 analyses was 1.5% RSD. The limits of detection for gaseous analytes (toluene in methanol as solvent) were determined to be as low as several hundred ppb or several hundred pg absolute without using any pre-concentration technique. Furthermore, the different GD source parameters like capillary distance, cathode-anode spacing, and GD source pressure with regards to the accessible elemental, structural, and molecular information were evaluated. It was demonstrated that each of these parameters has severe influence on the ratio of elemental, structural, and parent molecular information in chemical speciation analysis.

  8. General synthesis of transition metal oxides hollow nanospheres/nitrogen-doped graphene hybrids via metal-ammine complex chemistry for high performance lithium ion batteries.

    Science.gov (United States)

    Chen, Jiayuan; Wu, Xiaofeng; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Peng, Shengpan; Tan, Qiangqiang; Chen, Yunfa

    2017-08-30

    We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, in synthesizing hollow transition metal oxides (Co3O4, NiO, CuO-Cu2O and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high performance lithium ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co2+, Ni2+, Cu2+, or Zn2+)-ammine complex ions. Moreover, the hollowing process is well correlated with complexing capacity between metal ions and NH3 molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co2+, Ni2+, Cu2+, and Zn2+ ions, and no hollow structures formed for weak and/or non-complex Mn2+ and Fe3+ ions. Simultaneously, this novel strategy can also achieve the directly doping of nitrogen atoms into graphene framework. When used as anodic materials, the electrochemical performance of two typical hollow Co3O4 or NiO/nitrogen-doped graphene hybrids are evaluated. It is demonstrated that these unique nanostructed hybrids, in contrast with the bare counterparts, solid transition metal oxides/nitrogen-doped graphene hybrids, perform the significantly improved specific capacity, superior rate capability and excellent capacity retention. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Growth of ordered dusty structures in the glow discharge

    CERN Document Server

    Khakhaev, A; Khakhaev, Anatoly; Podriadtchikov, Sergey

    2004-01-01

    In plasma of direct-current glow discharge the dependence of ordered dusty structure volume, shape and density on plasma conditions were investigated. The structure is formed in a field of volume charge. In experimental investigations we used the aluminum oxide macroparticles with diameter up to 60 microns (size distribution function was not determined). Discharge tube was established vertically, has an internal diameter 2.6 cm and space gap between electrodes 45 cm. Particles were injected from the top end of the discharge tube into the plasma of spectral purity neon. Repeatability of randomized experiment results was better than 5% of the measured values. The areas of existence of various dusty ordered structures and their dependence on physical conditions in plasma (discharge current and pressure) were determined. When the interparticle distance in the structure is constant and particle positions have good time stability this structure was defined like "plasma crystal". Otherwise, we observed process of th...

  10. Flush-mounted probe diagnostics for argon glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang [Science and Technology on Space Physics Laboratory, Beijing 100076 (China)

    2014-09-15

    A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.

  11. Probiotic Bacteria Induce a ‘Glow of Health’

    Science.gov (United States)

    Smillie, Christopher; Varian, Bernard J.; Ibrahim, Yassin M.; Lakritz, Jessica R.; Alm, Eric J.; Erdman, Susan E.

    2013-01-01

    Radiant skin and hair are universally recognized as indications of good health. However, this ‘glow of health’ display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health. PMID:23342023

  12. Hollow chain-like beams

    CERN Document Server

    Cherepko, Dmitriy; Popkov, Ivan

    2012-01-01

    To generate hollow chain-like beams the diffraction of the first order Bessel beam by zone plate with two odd open Fresnel zone has been investigated. It has been shown that the capsules size is influenced by the number of the second odd open Fresnel zone and by the zone plate focal length. A hollow chain-like beam has been experimentally generated as a result of the first order Bessel beam diffraction by zone plate with the first and the ninth open Fresnel zones. The orbital angular momentum presence has been proved experimentally. The main features of the beam have been investigated. Sufficiently good agreement between experimental and numerically calculated results has been demonstrated.

  13. Compact lanthanum hexaboride hollow cathode.

    Science.gov (United States)

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

    A compact lanthanum hexaboride hollow cathode has been developed for space applications where size and mass are important and research and industrial applications where access for implementation might be limited. The cathode design features a refractory metal cathode tube that is easily manufactured, mechanically captured orifice and end plates to eliminate expensive e-beam welding, graphite sleeves to provide a diffusion boundary to protect the LaB6 insert from chemical reactions with the refractory metal tube, and several heater designs to provide long life. The compact LaB(6) hollow cathode assembly including emitter, support tube, heater, and keeper electrode is less than 2 cm in diameter and has been fabricated in lengths of 6-15 cm for different applications. The cathode has been operated continuously at discharge currents of 5-60 A in xenon. Slightly larger diameter versions of this design have operated at up to 100 A of discharge current.

  14. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  15. Efficient Overall Water-Splitting Electrocatalysis Using Lepidocrocite VOOH Hollow Nanospheres

    KAUST Repository

    Shi, Huanhuan

    2016-11-29

    Herein we report the control synthesis of lepidocrocite VOOH hollow nanospheres and further their applications in electrocatalytic water splitting for the first time. By tuning the surface area of the nanospheres, the optimal performance can be achieved with low overpotentials of 270 mV for the oxygen evolution reaction (OER) and 164 mV for the hydrogen evolution reaction (HER) at 10 mA cm-2 in 1 m KOH, respectively. Furthermore, when used as both the anode and cathode for overall water splitting, a low cell voltage of 1.62 V is required to reach the current density of 10 mA cm-2 , making the VOOH hollow nanospheres an efficient alternative to water splitting.

  16. Carbon supported trimetallic nickel-palladium-gold hollow nanoparticles with superior catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Shang, Changshuai; Hong, Wei; Wang, Jin; Wang, Erkang

    2015-07-01

    In this paper, Ni nanoparticles (NPs) are prepared in an aqueous solution by using sodium borohydride as reducing agent. With Ni NPs as the sacrificial template, hollow NiPdAu NPs are successfully prepared via partly galvanic displacement reaction between suitable metal precursors and Ni NPs. The as-synthesized hollow NiPdAu NPs can well dispersed on the carbon substrate. Transmission electron microscopy, X-ray diffraction and inductively coupled plasma mass spectrometry are taken to analyze the morphology, structure and composition of the as-synthesized catalysts. The prepared catalysts show superior catalytic activity and stability for methanol electrooxidation in alkaline media compared with commercial Pd/C and Pt/C. Catalysts prepared in this work show great potential to be anode catalysts in direct methanol fuel cells.

  17. Purification of nanoparticles by hollow fiber diafiltration

    Science.gov (United States)

    Veeken, J.

    2012-09-01

    Hollow Fiber Diafiltration (Hollow Fiber Tangential Flow Filtration) is an efficient and rapid alternative to traditional methods of nanoparticle purification such as ultracentrifugation, stirred cell filtration, dialysis or chromatography. Hollow Fiber Diafiltration can be used to purify a wide range of nanoparticles including liposomes, colloids, magnetic particles and nanotubes. Hollow Fiber Diafiltration is a membrane based method where pore size determines the retention or transmission of solution components. It is a flow process where the sample is gently circulated through a tubular membrane. With controlled replacement of the permeate or (dialysate), pure nanoparticles can be attained. Hollow Fiber Diafiltration can be directly scaled up from R&D volumes to production. By adding more membrane fibers and maintaining the operating parameters, large volumes can be processed in the same time with the same pressure, and flow dynamics as bench-scale volumes. Keywords: hollow fiber, Diafiltration, filtration, purification, tangential flow filtration.

  18. Hollow-core grating fiber

    Science.gov (United States)

    Barillé, R.; Tajalli, P.; Roy, P.; Ahmadi-kandjani, S.; Kucharski, S.; Ortyl, E.

    2012-02-01

    We propose a new type of hollow-core fiber where the propagation is ensured by a photoinduced self-pattern acting as a surface relief grating (SRG). The SRG is written by launching a suitable laser beam with proper polarization in a capillary glass fiber with the inner surface previously coated with an azopolymer thin film. Such a grating acts as a wavelength/angle dependant reflective mirror and enhances the confinement and the propagation of the light.

  19. Surface modification of polyester film by glow discharge tunnel at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    XU Xiang-yu; WANG Shou-guo; YE Tian-chun; JING Guang-yin; YU Da-peng

    2004-01-01

    A large-area improved dielectric barrier glow discharge tunnel has been developed for modifying the surface of polyester film at atmospheric pressure with argon and oxygen gas mixtures. The electrical properties of the glow discharge tunnel were studied by simultaneous measurement of the voltage and current. In addition, the effect of the glow discharge tunnel treatment on the surface of polyester film were studied. The resultant modifications of the surface properties of the treated samples were investigated through scanning probe microscopy and contact angle measurement.

  20. Note: Rapid reduction of graphene oxide paper by glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Zheng; Qian, Jiajing; Duan, Liangping; Qiu, Kunzan, E-mail: qiukz@zju.edu.cn; Yan, Jianhua; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Han, Zhao Jun [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000 (Australia)

    2015-05-15

    This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

  1. Aspects of Metal Surface Glowing Mechanisms with Intensive Electron Beam Bombardment

    Directory of Open Access Journals (Sweden)

    I.V. Barsuk

    2012-06-01

    Full Text Available The paper gives a brief description and analysis of the main physical processes which can have an effect on the glowing nature of metal element surfaces in different electric vacuum devices when they are bombarded by electron beams. It has been found that the electron glowing effects on metal surfaces according to the electron energy can be explained with the help of the transition scattering on plasma waves or just with the classical transition radiation effect. This fact is rather important in terms of classical physics interpretation of the observed glowing effects on metal surface elements and techniques optimization of metal and electron beams diagnostics as well.

  2. Cyclodextrin purification with hollow fibers

    Energy Technology Data Exchange (ETDEWEB)

    Berthod, A. (Univ. de Lyon 1, Villeubranne Cedex (France)); Jin, Heng Liang,; Armstrong, D.W. (Univ. of Missouri, Rolla (USA))

    1991-01-01

    Cyclodextrins are cyclic 1-4 linked oligomers of {alpha}-D-glucopyranose prepared from starch hydrolysis through enzymatic reactions. Mixtures of the three main cyclodextrins (CD), {alpha}-, {beta}-, and {gamma}-CDs, are always produced. A possible facile purification process is proposed. Permeation through hollow fibers made of a perfluorinated ionomer membrane. Nafion type, is shown to be an effective way to separate {alpha}-CD from {beta}- and {gamma}-CD. {Alpha}-CD with 95% purity was obtained after permeation through a Nafion hollow fiber of an equimolar 0.02 M solution of the three CDs. The fiber had a 56 cm{sup 2}/cm{sup 3} surface area per volume ratio. Kinetic studies and continuous extraction experiments with a 2-m coiled fiber showed that it is possible to obtain a 11.5 g {alpha}-CD solution with 92.4% purity or a 0.6 g {alpha}-CD solution with 97.2% purity, depending on the flow rate. The transport of CDs through the membrane could be due to moving water pools inside the ionomer. The small {alpha}-CD fits easily in such pools when the large {beta}- and {gamma}-CDs are excluded by steric hindrance. Temperature raises increased the permeation rates while decreasing the selectivity. The process could be scaled-up associating hollow fibers in bundle.

  3. Corrosion behavior of amorphous/nanocrystalline Al-Cr-Fe film deposited by double glow plasmas technique

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In order to improve the corrosion resistance of AZ31 magnesium alloy,the amorphous/nanocrystal Al-Cr-Fe film has been successfully prepared on AZ31 magnesium alloy by double glow plasma tech-nology.The amorphous/nanocrystalline consists of two different regions,i.e.,an amorphous layer on outmost surface and an underlying lamellar nanocrystalline layer with a grain size of less than 10 nm.The corrosion behavior of amorphous/nanocrystalline Al-Cr-Fe film in 3.5% NaCl solution is investi-gated using an electrochemical polarization measurement.Compared with the AZ31 magnesium alloy,the amorphous/nanocrystalline Al-Cr-Fe film exhibits more positive corrosion potentials and lower corrosion current densities than that of AZ31 magnesium alloy.XPS measurement reveals that the passive film formed on the Al-Cr-Fe film after the anodic polarization tests is strongly enriched in Cr2O3,Fe2O3 and Al2O3 at outer surface of the film and in the inner layer consists of Cr2O3,FeO and Al2O3.

  4. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  5. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Document Server

    Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  6. A novel hollowed CoO-in-CoSnO₃ nanostructure with enhanced lithium storage capabilities.

    Science.gov (United States)

    Guan, Cao; Li, Xianglin; Yu, Hong; Mao, Lu; Wong, Lydia Helena; Yan, Qingyu; Wang, John

    2014-11-21

    The search for well-defined porous/hollowed metal oxide nanocomposites for high performance energy storage is promising. Herein, atomic layer deposition (ALD) has been utilized for the construction of a novel hollowed wire-in-tube nanostructure of CoO-in-CoSnO3, for which Co2(OH)2CO3 nanowires are first obtained by a hydrothermal method and then deposited with ALD SnO2. After a proper thermal treatment, a CoO wire-void-CoSnO3 tube was formed with the decomposition of Co2(OH)2CO3 and its simultaneous reaction with the outer SnO2 layer. In this unique wire-in-tube structure, both CoO and CoSnO3 are promising materials for lithium ion battery anodes with high theoretical capacities, and the porous + hollow feature is essential for better electrode/electrolyte contact, shorter ion diffusion path and better structure stability. After a further facile carbon coating, the hollowed wire-in-tube structure delivered an improved capacity of 1162.1 mA h g(-1), which is much higher than that of the bare CoO nanowire. Enhanced rate capability and cycling stability have also been demonstrated with the structure, showing its promising application for the anode material of lithium ion battery. The work also demonstrated an effective way of using ALD SnO2 for electrochemical energy storage that ALD SnO2 plays a key role in the structure formation and also serves as both active material and surface coating.

  7. Hollow fibers for compact infrared gas sensors

    Science.gov (United States)

    Lambrecht, A.; Hartwig, S.; Herbst, J.; Wöllenstein, J.

    2008-02-01

    Hollow fibers can be used for compact infrared gas sensors. The guided light is absorbed by the gas introduced into the hollow core. High sensitivity and a very small sampling volume can be achieved depending on fiber parameters i.e. attenuation, flexibility, and gas exchange rates. Different types of infrared hollow fibers including photonic bandgap fibers were characterized using quantum cascade lasers and thermal radiation sources. Obtained data are compared with available product specifications. Measurements with a compact fiber based ethanol sensor are compared with a system simulation. First results on the detection of trace amounts of the explosive material TATP using hollow fibers and QCL will be shown.

  8. Metal-organic framework derived hollow polyhedron metal oxide posited graphene oxide for energy storage applications.

    Science.gov (United States)

    Ramaraju, Bendi; Li, Cheng-Hung; Prakash, Sengodu; Chen, Chia-Chun

    2016-01-18

    A composite made from hollow polyhedron copper oxide and graphene oxide was synthesized by sintering a Cu-based metal-organic framework (Cu-MOF) embedded with exfoliated graphene oxide. As a proof-of-concept application, the obtained Cu(ox)-rGO materials were used in a lithium-ion battery and a sodium-ion battery as anode materials. Overall, the Cu(ox)-rGO composite delivers excellent electrochemical properties with stable cycling when compared to pure CuO-rGO and Cu-MOF.

  9. Multi-anode ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Aleksey E. (South Setauket, NY); Smith, Graham (Port Jefferson, NY); Mahler, George J. (Rocky Point, NY); Vanier, Peter E. (Setauket, NY)

    2010-12-28

    The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.

  10. The analysis of high amplitude of potential oscillations near the hollow cathode of ion thruster

    Science.gov (United States)

    Qin, Yu; Xie, Kan; Guo, Ning; Zhang, Zun; Zhang, Cen; Gu, Zengjie; Zhang, Yu; Jiang, Zhaorui; Ouyang, Jiting

    2017-05-01

    The influence of gas flow, current level, and different shapes of anode on the oscillation amplitude and the characteristics of the hollow cathode discharge were investigated. The average plasma potential, temporal measurements of plasma potential, ion density, the electron temperature, as well as waveforms of plasma potential for test conditions were measured. At the same time, the time-resolved images of the plasma plume were also recorded. The results show that the potential oscillations appear at high discharge current or low flow rate. The potential oscillation boundaries, the position of maximum amplitude of plasma potential, and the position where the highest ion density was observed, were found. Both of the positions are affected by different shapes of anode configurations. This high amplitude of potential oscillations is ionization-like instabilities. The xenon ions ionized in space was analyzed for the fast potential rise and spatial dissipation of the space xenon ions was the reason for the gradual potential delay.

  11. RF Glow-discharge Enhanced Production of Oxygen from Carbon Dioxide

    Science.gov (United States)

    Shi, Zhong; Ash, Robert L.

    1996-10-01

    An experimental study of energy-efficient, RF glow-discharge enhanced production of oxygen from carbon dioxide is conducted. This effort has important applications for advanced life support system at space station to recover oxygen from waste carbon dioxide and in situ resource utilization for round trip planetary missions.(R. L. Ash, W. L. Dowler, and G. Varsi, Acta Astronautica, 5), 705, (1978). The system consists of a glow-discharge chamber and a silver permeation membrane used to separate oxygen from other species. The behavior of RF glow-discharge and the oxygen production rate was investigated as functions of discharge power, eletrodes geometry, membrane operating temperature, gas pressure, and RF frequency. Description of the experimental set up and the measured results compared with previous DC glow-discharge data (D. Wu, R. A. Outlaw, and R. L. Ash, J. Applied Phys., 74), 4990, (1993). will be presented at the conference.

  12. Microhollow Glow Discharge Instrument for In Situ Lunar Surface Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and Penn State University (PSU) propose to develop a highly sensitive spectrometer based on glow discharge plasma emission for the...

  13. A single TiO2-coated side-glowing optical fiber for photocatalytic wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    HU Yan; XU Jingjing; YUAN Chunwei; LIN Jian; YIN Zhidong

    2005-01-01

    By means of TiO2-layer-on-SiO2-layer, anatase TiO2 was deposited on novel side- glowing optical fibers, which can provide side UV radiation along the whole fiber length. FE-SEM images show that the double layers adhered well to the side-glowing optical fiber, and the TiO2 coating was homogeneous and smooth. The decomposition reaction of reactive brilliant red dye X-3B on a single TiO2-coated side-glowing optical fiber indicated that the side-scattering UV light intensity was strong enough for photocatalytic oxidation reaction. Therefore, TiO2-coated side-glowing optical fibers open up a new way to use the optical fiber reactor in photocatalytic wastewater treatment.

  14. Effect of Ne Glow Discharge on Ion Density Control in LHD

    Institute of Scientific and Technical Information of China (English)

    S.Morita; M. Goto; S. Masuzaki; H. Suzuki; K. Tanaka; H. Nozato; Y. Takeiri; J. Miyazawa; LHD esperimental group

    2004-01-01

    Neon glow discharge cleaning was firstly attempted in Large Helical Device (LHD) instead of He glow discharge to remove hydrogen neutrals and to control the ion density, ni. The Ne glow discharge continued for 8 hours overnight after a three-day experiment. At the second night Halpha emission became weaker than the emission usually observed in the He glow discharge. A clear reduction of the hydrogen influx was also observed in neutral beam injection (NBI) discharges with Ne puff, whereas the neon recycling was strongly enhanced with appearance of a flat density profile. As a result, the lowest density limit was further reduced down to 0.2 times10 13 ,cm-3. The use of Ar puff formed a peaked density profile with a high Ti of 7 keV.

  15. Hollow system with fin. Transient Green function method combination for two hollow cylinders

    Directory of Open Access Journals (Sweden)

    Buikis Andris

    2017-01-01

    Full Text Available In this paper we develop mathematical model for three dimensional heat equation for the system with hollow wall and fin and construct its analytical solution for two hollow cylindrical sample. The method of solution is based on Green function method for one hollow cylinder. On the conjugation conditions between both hollow cylinders we construct solution for system wall with fin. As result we come to integral equation on the surface between both hollow cylinders. Solution is obtained in the form of second kind Fredholm integral equation. The generalizing of Green function method allows us to use Green function method for regular non-canonical domains.

  16. The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

    Science.gov (United States)

    Luginbuhl, C. B.; Boley, P. A.; Davis, D. R.; Duriscoe, D. M.

    2015-03-01

    Using a wavelength-generalized version of the Garstang (1991) model, we evaluate overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED lamps. We conclude for both professional, and especially cultural (visual), astronomy, that low-pressure sodium and narrow-spectrum amber LED lamps cause much less sky glow than all broad-spectrum sources.

  17. The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

    Science.gov (United States)

    2015-01-01

    MAR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE The Effects of Lamp Spectral Distribution on Sky Glow...overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED... lamps . We conclude for both professional, and especially cultural (visual), astronomy, that low-pressure sodium and narrowspectrum amber LED lamps

  18. Effects of norms, warm-glow and time use on household recycling

    OpenAIRE

    Halvorsen, Bente

    2004-01-01

    Abstract: The aim of this paper is to quantify the relative importance of motivations based on warm-glow, social and moral norms and cost of time used recycling on household recycling efforts. We also test for crowding-out of intrinsic motivations when recycling is perceived as mandatory. We find that the most important variable increasing household recycling efforts is agreeing that recycling is a pleasant activity in itself, which may be interpreted as a warm-glow effect. The...

  19. Second Order Fluid Glow Discharge Model Sustained by Different Source Terms%Second Order Fluid Glow Discharge Model Sustained by Different Source Terms

    Institute of Scientific and Technical Information of China (English)

    D. GUENDOUZ; A. HAMID; A. HENNAD

    2011-01-01

    Behavior of charged particles in a DC low pressure glow discharge is studied. The electric properties of the glow discharge in argon, maintained by a constant source term with uni- form electron and ion generation, between two plane electrodes or by secondary electron emission at the cathode, are determined. A fluid model is used to solve self-consistently the first three moments of the Boltzmann equation coupled with the Poisson equation. The stationary spatial distribution of the electron and ion densities, the electric potential, the electric field, and the electron energy, in a two-dimensional (2D) configuration, are presented.

  20. TL glow curve analysis of UV, beta and gamma induced limestone collected from Amarnath holy cave

    Directory of Open Access Journals (Sweden)

    Vikas Dubey

    2015-01-01

    Full Text Available The paper reports themoluminescence glow curve analysis of UV (ultraviolet, β (beta and γ (gamma induced limestone collected from Amarnath holy cave. The collected natural sample was characterized by X-ray diffraction (XRD technique and crystallite size calculated by Scherer's formula. Surface morphology and particle size was calculated by transmission electron microscopy (TEM study. Effect of annealing temperature on collected lime stone examined by TL glow curve study. The limestone was irradiated by UV radiation (254 nm source and the TL glow curve recorded for different UV exposure time. For beta irradiation Sr90 source was used and is shows intense peak at 256 °C with a shoulder peak at higher temperature range. For gamma radiation Co60 source and TL glow curve recorded for different doses of gamma. The kinetic parameters calculation was performed for different glow curve by computerized glow curve deconvolution (CGCD technique. The chemical composition of natural limestone was analyzed by energy dispersive X-ray spectroscopy (EDXS.

  1. Modeling plasma glow discharges in Air near a Mach 3 bow shock with KRONOS

    Science.gov (United States)

    Rassou, Sebastien; Labaune, Julien; Packan, Denis; Elias, Paul-Quentin

    2016-09-01

    In this work, plasma glow discharge in Air is modeled near a Mach 3 bow shock. Numerical simulations are performed using the coupling KRONOS which have been developed at ONERA. The flow field is modeled using the code CFD: CEDRE from ONERA and the electrical and plasma part by the EDF open-source code CODE_SATURNE. The plasma kinetic modeling consists on a two-term Boltzmann equation solver and a chemical reaction solver depending of the electric field. The coupling KRONOS is fully parallelized and run on ONERA supercomputers. The shock wave is formed by the propagation of a supersonic flow (M = 3) through a truncated conical model mounted with a central spike. Depending on the spike's voltage value, corona, glow or arc regime could be obtained in a steady flow. The parameters for the supersonic flow and the spike configurations are chosen to be in glow discharge regime and to reproduce the experimental setup. In our simulations, 12 species and 80 reactions (ionization, electronic or vibrational excitation, attachment etc ...) are considered to properly model the glow discharge and the afterglow. In a stationary flow, glow discharge is observed only at the upstream of the shock wave near the high voltage spike. Behind the bow shock, in the afterglow, negative ions are provided by electrons attachment with O2. The negative ions flow convection ensures the electrical conduction and the establishment of the glow discharge.

  2. Study of the glow curve structure of the minerals separated from black pepper (Piper nigrum L.)

    Science.gov (United States)

    Guzmán, S.; Ruiz Gurrola, B.; Cruz-Zaragoza, E.; Tufiño, A.; Furetta, C.; Favalli, A.; Brown, F.

    2011-04-01

    The inorganic mineral fraction extracted from black pepper (Piper nigrum L.) has been analysed using a thermoluminescence (TL) method, investigating the glow curve structure, including an evaluation of the kinetic parameters. Different grain sizes, i.e. 10, 74, and 149 μm, were selected from commercial black pepper. The X-ray diffraction of the inorganic fraction shows that quartz is the main mineral present in it. The samples were exposed to 1-25 kGy doses by gamma rays of 60Co in order to analyse the thermally stimulated luminescence response as a function of the delivered dose. The glow curves show a complex structure for different grain sizes of the pepper mineral samples. The fading of the TL signal at room temperature was obtained after irradiation, and it was observed that the maximum peaks of the glow curves shift towards higher values of the temperature when the elapsed time from irradiation increases. It seems that the fading characteristic may be related to a continuous trap distribution responsible for the complex structure of the glow curve. Similar glow curves structure behaviour was found under ultraviolet irradiation of the samples. The activation energy and the frequency factor were determined from the glow curves of different grain sizes using a deconvolution programme because of the evident complexity of the structure.

  3. Traumatic and nontraumatic perforation of hollow viscera.

    Science.gov (United States)

    Espinoza, R; Rodríguez, A

    1997-12-01

    Hollow viscus injuries are usually managed with few complications. However, if their diagnosis is delayed, or if reparative suture closure should fail, the patient is placed at risk of multiple organ failure. This article presents diagnostic approaches, emphasizing imaging modalities, and therapeutic strategies for three clinical scenarios of hollow viscus perforation: 1) acute appendicitis, 2) gastroduodenal peptic ulcer disease, and 3) trauma.

  4. Adsorption characteristics of activated carbon hollow fibers

    OpenAIRE

    2009-01-01

    Carbon hollow fibers were prepared with regenerated cellulose or polysulfone hollow fibers by chemical activation using sodium phosphate dibasic followed by the carbonization process. The activation process increases the adsorption properties of fibers which is more prominent for active carbone fibers obtained from the cellulose precursor. Chemical activation with sodium phosphate dibasic produces an active carbon material with both mesopores and micropores.

  5. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  6. Platinum and Iridium Coatings Obtained by Double Glow Plasma Technology

    Institute of Scientific and Technical Information of China (English)

    WU Wangping; CHEN Zhaofeng; CHEN Zhou; CONG Xiangna; QIU Jinlian

    2012-01-01

    Pt and Ir coatings were produced by double glow plasma technology on the surface of Ti alloy substrates.The chemical compositions of the coatings were determined by X-ray diffraction and X-ray photoelectron spectroscopy.The microstructure and morphology of the coatings were observed by scanning electron microscopy.The hardness and elastic modulus of the coatings were estimated by nanoindentation.The measurements of adhesive forces of the coatings were performed with scratch tester.The results indicated that the Pt and Ir coatings displayed the preferred (220) orientation due to the initial nuclei with preferred growth on the surface of the substrates.The interface between the Pt coating and substrate exhibited no evidence of delamination.The Ir coating was composed of irregular columnar grains with many nanovoids at the interface between the coating and substrate.The mean values of hardness for Pt and Ir coatings were 0.9 GPa and 9 GPa,respectively.The elastic modulus of Pt and Ir coatings were 178 GPa and 339 GPa,respectively.The adhesive forces of the Pt and Ir coatings were about 66.4 N and 55 N,respectively.The Pt and Ir coatings adhered well to the Ti alloy substrates.

  7. Aqueous organic dye discoloration induced by contact glow discharge electrolysis.

    Science.gov (United States)

    Wang, Lei

    2009-11-15

    In this study, effects of applied voltage, types of electrolytes, initial substrate concentration, radical scavengers and iron salts on the aqueous polar brilliant B (PBB) discoloration induced by contact glow discharge electrolysis (CGDE) were examined. Experimental results showed that the PBB discoloration proceeded faster in chloride solution than in phosphate or sulfate solutions. Increasing the applied voltage from 450V to 550V did not enhance the discoloration when the applied current was kept constant. Addition of a small amount of hydroxyl scavengers (methanol) to the solution decreased the discoloration, whereas addition of a large amount of methanol increased the discoloration. During the treatment, TOC of the solution smoothly decreased whereas COD of the solution gradually increased due to the production of H(2)O(2) in the liquid phase. Iron salts enhanced the discoloration significantly due to the additional Fenton reaction. Higher initial PBB concentration resulted in lower color removal efficiency, indicating that the PBB discoloration by CGDE did not observe the first-order reaction kinetics in inert electrolytic solutions.

  8. Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

    Institute of Scientific and Technical Information of China (English)

    GAO Jinzhang; MA Dongping; GUO Xiao; WANG Aixiang; FU Yan; WU Jianlin; YANG Wu

    2008-01-01

    This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant κ and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. Mol-1 and the pre-exponential factor k0 of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N, N-dimethyl -p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

  9. Fabrication of functional hollow carbon spheres with large hollow interior as active colloidal catalysts

    Institute of Scientific and Technical Information of China (English)

    Qiang Sun; Guanghui Wang; Wencui Li; Xiangqian Zhang; Anhui Lu

    2012-01-01

    In this study,we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior,which can act as active colloidal catalysts.The method includes the following steps:first,hollow polymer spheres with large hollow interior were prepared using sodium oleate as the hollow core generator,and 2,4-dihydroxybenzoic acid and hexamethylene tetramine (HMT) as the polymer precursors under hydrothermal conditions; Fe3+ or Ag+ cations were then introduced into the as-prepared hollow polymer spheres through the carboxyl groups; finally,the hollow polymer spheres can be pseudomorphically converted to hollow carbon spheres during pyrolysis process,meanwhile iron or silver nanoparticles can also be formed in the carbon shell simultaneously.The structures of the obtained functional hollow carbon spheres were characterized by TEM,XRD,and TG.As an example,Ag-doped hollow carbon spheres were used as colloid catalysts which showed high catalytic activity in 4-nitrophenol reduction reaction.

  10. POROUS WALL, HOLLOW GLASS MICROSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to &apos

  11. Interfacial investigation and mechanical properties of glass-Al-glass anodic bonding process

    Science.gov (United States)

    Hu, Lifang; Xue, Yongzhi; Shi, Fangrong

    2017-10-01

    Glass-Al-glass with Al as common anode was successfully bonded together through the anodic bonding process. SEM and EDS were conducted to investigate the interfacial structure of the glass-Al-glass samples. Special attention was given to the element distribution after the bonding process. The element profile of the transitional layer was investigated by glow discharge optical emission microscopy. The results showed that ion migration played an important role during the anodic bonding process, Na+ would precipitate from the back of the glass, and a Na+ depletion region formed at the bonding interface. At the same time, O2‑ diffused into the bonding interface and reacted with the Al, which resulted in a successful bonding process. Furthermore, Al migrated into the glass, which could enhance the bonding process. The peak current of the glass-Al-glass bonding was two times larger than that of the Al-glass bonding, which meant that the glass-Al-glass bonding process could be considered equivalent to two individual Al-glass bonding processes. Tensile strength tests showed that the glass was fractured, and the fractures propagated into the bonding interface, which indicated a reliable bonding process.

  12. Fortissimo: A Japanese Space Test Of Bare Wire Anode Tethers

    Science.gov (United States)

    Johnson, Les; Fujii, H. A.; Sanmartin, J. R.

    2008-01-01

    A Japanese led international team is developing a suborbital test of orbital-motion-limited (OML) bare wire anode current collection for application to electrodynamic tether (EDT) propulsion. The tether is a tape with a width of 25 mm, thickness of 0.05 mm, and is 300 m in length. This will be the first space test of OML theory. The mission will launch in the summer of 2009 using an S520 Sounding Rocket. During ascent, and above approx. 100 km in attitude, the tape tether will be deployed at a rate of approx. 8 m/s. Once deployed, the tape tether will serve as an anode, collecting ionospheric electrons. The electrons will be expelled into space by a hollow cathode device, thereby completing the circuit and allowing current to flow. The total amount of current collected will be used to assess the validity of OML theory. This paper will describe the objectives of the proposed mission, the technologies to be employed, and the application of the results to future space missions using EDTs for propulsion or power generation.

  13. In-flight observation of long duration gamma-ray glows by aircraft

    Science.gov (United States)

    Kochkin, Pavlo; (Lex) van Deursen, A. P. J.; de Boer, Alte; Bardet, Michiel; Allasia, Cedric; Boissin, Jean Francois; Ostgaard, Nikolai

    2017-04-01

    The Gamma-Ray Glow is a long-lasting (several seconds to minutes) X- and gamma radiation presumably originated from high-electric field of thunderclouds. Such glows were previously observed by aircraft, balloons, and from the ground. When detected on ground with other particles, i.e. electrons and neutrons, they are usually called Thunderstorm Ground Enhancements (TGEs). Their measured spectra are often consistent with Relativistic Runaway Electron Avalanche (RREA) mechanism. That is why RREA is a commonly accepted explanation for their existence. The gamma-ray glows are observed to be interrupted by lightning discharge, which terminates the high-electric field region. In January 2016 an Airbus A340 factory test aircraft was performing intentional flights through thunderstorms over Northern Australia. The aircraft was equipped with a dedicated in-flight lightning detection system called ILDAS (http://ildas.nlr.nl). The system also contained two scintillation detectors each with 38x38 mm cylinder LaBr3 crystals. While being at 12 km altitude the system detected a gamma-ray flux enhancement 30 times the background counts. It lasted for 20 seconds and was abruptly terminated by a lightning flash. The flash hit the aircraft and its parameters were recorded with 10 ns sampling time including gamma radiation. Ground-based lightning detection network WWLLN detected 4 strikes in the nearby region, all in association with the same flash. The ILDAS system recorded the time-resolved spectrum of the glow. In 6 minutes, after making a U-turn, the aircraft passed the same glow region. Smaller gamma-ray enhancement was again detected. In this presentation we will show the mapped event timeline including airplane, gamma-ray glow, WWLLN, and cloud data. We will discuss the glow's properties, i.e. intensity and differential spectrum, and its possible origin. This result will also be compared to previously reported observations.

  14. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  15. Designing hollow nano gold golf balls.

    Science.gov (United States)

    Landon, Preston B; Mo, Alexander H; Zhang, Chen; Emerson, Chris D; Printz, Adam D; Gomez, Alan F; DeLaTorre, Christopher J; Colburn, David A M; Anzenberg, Paula; Eliceiri, Matthew; O'Connell, Connor; Lal, Ratnesh

    2014-07-09

    Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure.

  16. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  17. Analysis of MESSENGER high-resolution images of Mercury's hollows and implications for hollow formation

    Science.gov (United States)

    Blewett, David T.; Stadermann, Amanda C.; Susorney, Hannah C.; Ernst, Carolyn M.; Xiao, Zhiyong; Chabot, Nancy L.; Denevi, Brett W.; Murchie, Scott L.; McCubbin, Francis M.; Kinczyk, Mallory J.; Gillis-Davis, Jeffrey J.; Solomon, Sean C.

    2016-09-01

    High-resolution images from MESSENGER provide morphological information on the nature and origin of Mercury's hollows, small depressions that likely formed when a volatile constituent was lost from the surface. Because graphite may be a component of the low-reflectance material that hosts hollows, we suggest that loss of carbon by ion sputtering or conversion to methane by proton irradiation could contribute to hollows formation. Measurements of widespread hollows in 565 images with pixel scales <20 m indicate that the average depth of hollows is 24 ± 16 m. We propose that hollows cease to increase in depth when a volatile-depleted lag deposit becomes sufficiently thick to protect the underlying surface. The difficulty of developing a lag on steep topography may account for the common occurrence of hollows on crater central peaks and walls. Disruption of the lag, e.g., by secondary cratering, could restart growth of hollows in a location that had been dormant. Images at extremely high resolution (~3 m/pixel) show that the edges of hollows are straight, as expected if the margins formed by scarp retreat. These highest-resolution images reveal no superposed impact craters, implying that hollows are very young. The width of hollows within rayed crater Balanchine suggests that the maximum time for lateral growth by 1 cm is ~10,000 yr. A process other than entrainment of dust by gases evolved in a steady-state sublimation-like process is likely required to explain the high-reflectance haloes that surround many hollows.

  18. Focused beams of fast neutral atoms in glow discharge plasma

    Science.gov (United States)

    Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

    2017-06-01

    Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

  19. Engineering empty space between Si nanoparticles for lithium-ion battery anodes.

    Science.gov (United States)

    Wu, Hui; Zheng, Guangyuan; Liu, Nian; Carney, Thomas J; Yang, Yuan; Cui, Yi

    2012-02-01

    Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles. Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation. To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes. The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled. The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention).

  20. Hollow cathode modeling: II. Physical analysis and parametric study

    Science.gov (United States)

    Sary, Gaétan; Garrigues, Laurent; Boeuf, Jean-Pierre

    2017-05-01

    A numerical emissive hollow cathode model which couples plasma and thermal aspects of the NASA NSTAR cathode has been presented in a companion paper and simulation results obtained using the plasma model were compared to experimental data. We now compare simulation results with measurements using the full coupled model. Inside the cathode, the simulated plasma density profile agrees with the experimental data up to the ±50% experimental uncertainty while the simulated emitter temperature differs from measurements by at most 5 K. We then proceed to an analysis of the cathode discharge both inside the cathode where electron emission is dominant and outside in the near plume where electron transport instabilities are important. As observed previously in the literature, the total emitted electron current is much larger (34 {{A}}) than the set discharge current collected at the anode (13 {{A}}) while ionization plays a negligible role. Extracted electrons are emitted from a region much shorter than the full emitter (0.9 {{cm}} versus 2.5 {{cm}}). The influence of an applied axial magnetic field in the plume is also assessed and we observe that it leads to a 10-fold increase of the plasma density 1 cm downstream of the orifice entrance while the simulated discharge potential at the anode is increased from 10 {{V}} up to 35.5 {{V}}. Lastly, we perform a parametric study on both the operating point (discharge current, mass flow rate) and design (inner radius) of the cathode. The simulated useful operating envelope is shown to be limited at low discharge current mostly because of the probable ion sputtering of the emitter and at high discharge current because of emitter evaporation, plasma oscillations and sputtering of the keeper electrode. The behavior of the cathode is also analyzed w.r.t. its internal radius and simulation results show that the useful emitter length scales linearly with the cathode radius.

  1. Design and Manufacturing Processes of Long-Life Hollow Cathode Assemblies

    Science.gov (United States)

    Patterson, Michael J. (Inventor); Verhey, Timothy R. (Inventor); Soulas, George C. (Inventor)

    2002-01-01

    The design and manufacturing processes for Hollow Cathode Assemblies (HCA's) that operate over a broad range of emission currents up to 30 Amperes, at low potentials, with lifetimes in excess of 17,500 hours. The processes include contamination control procedures which cover hollow cathode component cleaning procedures, gas feed system designs and specifications, and hollow cathode activation and operating procedures to thereby produce cathode assemblies that have demonstrated stable and repeatable operating conditions, for both the discharge current and voltage. The HCA of this invention provides lifetimes of greater than 10,000 hours, and expected lifetimes of greater than 17,500 hours, whereas the present state-of-the-art is less than 500 hours at emission currents in excess of 1 Ampere. Stable operation is provided over a large range of operating emission currents, up to a 6:1 ratio, and this HCA can emit electron currents of up to 30 Amperes in magnitude to an external anode that simulates the current drawn to a space plasma at voltages of less than 20 Volts.

  2. Fabricating a hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Fatih Sari

    2012-01-01

    Full Text Available

    Obturators are generally used in the rehabilitation of the maxillectomy defects. Ideally, obturators should be light, properly fit and construction should be made easily. By decreasing the weight of the prosthesis, the retention and stability may be optimized to allow the obturator for function comfortably during mastication, phonation, and deglutition. In this case, a 65-year-old male patient underwent surgical removal of left part of the maxilla due to the squamous cell carcinoma. In this technique fabrication of a hollow bulb obturator prosthesis as a single unit in heat-cured acrylic resin using a single-step flasking procedure was described. The patient’s functional and esthetic expectations were satisfied.

  3. Non-Thermal Equilibrium Atmospheric Pressure Glow-Like Discharge Plasma Jet

    Science.gov (United States)

    Chang, Zhengshi; Yao, Congwei; Zhang, Guanjun

    2016-01-01

    Non-thermal equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications, and the uniform APPJ is more favored. Glow discharge is one of the most effective methods to obtain the uniform discharge. Compared with the glow dielectric barrier discharge (DBD) in atmospheric pressure, pure helium APPJ shows partial characteristics of both the glow discharge and the streamer. In this paper, considering the influence of the Penning effect, the electrical and optical properties of He APPJ and Ar/NH3 APPJ were researched. A word “Glow-like APPJ” is used to characterize the uniformity of APPJ, and it was obtained that the basic characteristics of the glow-like APPJ are driven by the kHz AC high voltage. The results can provide a support for generating uniform APPJ, and lay a foundation for its applications. supported by National Natural Science Foundation of China (Nos. 51307133, 51125029, 51221005) and the Fundamental Research Funds for the Central Universities of China (Nos. xjj2012132, xkjc2013004)

  4. Hollow-core tapered coupler for large inner diameter hollow-core optical fibers

    Institute of Scientific and Technical Information of China (English)

    Guiyao Zhou(周桂耀); Zhiyun Hou(侯峙云); Lantian Hou(侯蓝田); Jigang Liu(刘继刚)

    2003-01-01

    A novel hollow-core tapered coupler has been theoretically designed and fabricated by fiber drawing machine. The coupler's inner wall is coated with a polycrystalline GeO2 film. The coupling loss of hollow-core tapered coupler is about 0.2 dB. Hollow-core tapered coupler reduces the transmission loss of hollow-core optical fiber (HCOF) by 0.5 dB/m, therefore the coupler is suitable for coupling high power CO2 laser in industrial application.

  5. Hollow Alveolus-Like Nanovesicle Assembly with Metal-Encapsulated Hollow Zeolite Nanocrystals.

    Science.gov (United States)

    Dai, Chengyi; Zhang, Anfeng; Liu, Min; Gu, Lin; Guo, Xinwen; Song, Chunshan

    2016-08-23

    Inspired by the vesicular structure of alveolus which has a porous nanovesicle structure facilitating the transport of oxygen and carbon dioxide, we designed a hollow nanovesicle assembly with metal-encapsulated hollow zeolite that would enhance diffusion of reactants/products and inhibit sintering and leaching of active metals. This zeolitic nanovesicle has been successfully synthesized by a strategy which involves a one-pot hydrothermal synthesis of hollow assembly of metal-containing solid zeolite crystals without a structural template and a selective desilication-recrystallization accompanied by leaching-hydrolysis to convert the metal-containing solid crystals into metal-encapsulated hollow crystals. We demonstrate the strategy in synthesizing a hollow nanovesicle assembly of Fe2O3-encapsulated hollow crystals of ZSM-5 zeolite. This material possesses a microporous (0.4-0.6 nm) wall of hollow crystals and a mesoporous (5-17 nm) shell of nanovesicle with macropores (about 350 nm) in the core. This hierarchical structure enables excellent Fe2O3 dispersion (3-4 nm) and resistance to sintering even at 800 °C; facilitates the transport of reactant/products; and exhibits superior activity and resistance to leaching in phenol degradation. Hollow nanovesicle assembly of Fe-Pt bimetal-encapsulated hollow ZSM-5 crystals was also prepared.

  6. Optimization of the 3-Point Bending Failure of Anodized Aluminum Formed in Tartaric/Sulphuric Acid Using Doehlert Design

    Science.gov (United States)

    Bensalah, W.; Feki, M.; De-Petris Wery, M.; Ayedi, H. F.

    2015-02-01

    The bending failure of anodized aluminum in tartaric/sulphuric acid bath was modeled using Doehlert design. Bath temperature, anodic current density, sulphuric acid, and tartaric acid concentrations were retained as variables. Thickness measurements and 3-point bending experiments were conducted. The deflection at failure ( D f) and the maximum load ( F m) of each sample were, then, deducted from the corresponding flexural responses. The treatment of experimental results has established mathematical models of second degree reflecting the relation of cause and effect between the factors and the studied properties. The optimum path study of thickness, deflection at failure, and maximum load, showed that the three optima were opposite. Multicriteria optimization using the desirability function was achieved in order to maximize simultaneously the three responses. The optimum conditions were: C tar = 18.2 g L-1, T = 17.3 °C, J = 2.37 A dm-2, C sul = 191 g L-1, while the estimated response values were e = 57.7 µm, D f = 5.6 mm, and F m = 835 N. Using the established models, a mathematical correlation was found between deflection at failure and thickness of the anodic oxide layer. Before bending tests, aluminum oxide layer was examined by scanning electron microscopy (SEM) and atomic force microscopy. After tests, the morphology and the composition of the anodic oxide layer were inspected by SEM, optical microscopy, and glow-discharge optical emission spectroscopy.

  7. DEVELOPMENT OF TECHNOLOGY FOR ANODE BALL PRODUCTION

    Directory of Open Access Journals (Sweden)

    G. V. Kozhevnikova

    2015-01-01

    Full Text Available Technology of copper anode balls manufacturing by means of cross-wedge rolling method is developed. The technology satisfies the requirements towards anode balls’ crystalline structure, form and geometrical dimensions accuracy.

  8. STUDY OF ANODIC OVERVOLTAGE IN NEODYMIUM ELECTROLYSIS

    Institute of Scientific and Technical Information of China (English)

    K.R. Liu; J.S. Chen; Q. Han; X.J. Wei

    2003-01-01

    The anodic overvoltage of neodymium electrolysis was determined by slow scanning oscillogram. The effects of some factors, i.e. the temperature, the anodic current density, the concentration of Nd2O3 and the components of the electrolyte were investigated and the approaches to decrease the anodic overvoltage were also discussed. The results show that the anodic overvoltage increases with the anodic current density and decreases with the increasing temperature. The linear relation between the anodic overvoltage and the current density corresponding to Tafel equation is determined to some extent. The anodic overvoltage decreases with the increasing concentrations of LiF and NdF3. It also decreases by controlling the anodic current density properly, increasing the temperature or the concentrations of LiF and NdF3 and the reducing polar distance.

  9. Hollow rhodoliths increase Svalbard's shelf biodiversity

    Science.gov (United States)

    Teichert, Sebastian

    2014-11-01

    Rhodoliths are coralline red algal assemblages that commonly occur in marine habitats from the tropics to polar latitudes. They form rigid structures of high-magnesium calcite and have a good fossil record. Here I show that rhodoliths are ecosystem engineers in a high Arctic environment that increase local biodiversity by providing habitat. Gouged by boring mussels, originally solid rhodoliths become hollow ecospheres intensely colonised by benthic organisms. In the examined shelf areas, biodiversity in rhodolith-bearing habitats is significantly greater than in habitats without rhodoliths and hollow rhodoliths yield a greater biodiversity than solid ones. This biodiversity, however, is threatened because hollow rhodoliths take a long time to form and are susceptible to global change and anthropogenic impacts such as trawl net fisheries that can destroy hollow rhodoliths. Rhodoliths and other forms of coralline red algae play a key role in a plurality of environments and need improved management and protection plans.

  10. optimizing compressive strength characteristics of hollow building ...

    African Journals Online (AJOL)

    eobe

    This paper evaluates the compressive strength of sandcrete hollow building blocks when its sand fraction is partially replaced ... defines sandcrete blocks as composite materials made .... industry as well as the economy of Nigeria, if there is no.

  11. BOX-DEATH HOLLOW ROADLESS AREA, UTAH.

    Science.gov (United States)

    Weir, Gordon W.; Lane, Michael

    1984-01-01

    Geologic mapping, geochemical sampling, and a search for prospects and mineralized rock in the Box-Death Hollow Roadless Area, Utah indicate that there is little promise for the occurrence of mineral or energy resources in the area. Additional exploratory drilling by industry seems warranted if wells elsewhere in the region find oil or gas in strata as yet untested in the Box-Death Hollow Roadless Area.

  12. Mode characteristics of hollow core Bragg fiber

    Institute of Scientific and Technical Information of China (English)

    Minning Ji; Zhidong Shi; Qiang Guo

    2005-01-01

    Analytical expression to calculate propagation constant and mode field of the hollow core Bragg fiber is derived. Numerical results are presented. It is shown that the fundamental mode of the hollow core Bragg fiber is circularly symmetric TE01 mode with no polarization degeneracy, while the higher order mode may be HE11, TM01, or TE02 etc.. This property is different from conventional optical fiber that its fundamental mode is the linearly polarized HE11 mode and is polarization degeneracy.

  13. Self-Consistent Model for Pulsed Direct-Current N2 Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    Liu Chengsen; Wang Dezhen

    2005-01-01

    A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column).Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.

  14. Does exclusion of protest zeros and warm-glow bidders cause selection bias in Contingent Valuation?

    DEFF Research Database (Denmark)

    Grammatikopoulou, Ioanna; Olsen, Søren Bøye; Pouta, Eija

    different models to test for the potential impacts of how these positive warm glow and protest zero bidders are treated. We first exclude the warm glow cases, secondly we include them, and, finally, we correct for selection bias by using the Full Information Maximum Likelihood method for grouped data model....... Our findings show that removal of warm glow positive bidders does not distort the WTP estimate in any significant way. However, using the same approach for protest zero bidders, we find strong evidence of selection bias associated with removal of protest zero responses. Specifically, WTP estimates...... obtained after removal of protest responses are found to be biased downwards and the aggregated welfare measures would be significantly underestimated in our case. These results suggest that there could be serious consequences associated with the common approach of removing protest zero bidders in CVM....

  15. Apocenter glow in eccentric debris disks: implications for Fomalhaut and $\\epsilon$ Eridani

    CERN Document Server

    Pan, Margaret; Kuchner, Marc J

    2016-01-01

    Debris disks often take the form of eccentric rings with azimuthal asymmetries in surface brightness. Such disks are often described as showing "pericenter glow", an enhancement of the disk brightness in regions nearest the central star. At long wavelengths, however, the disk apocenters should appear brighter than their pericenters: in the long wavelength limit, we find the apocenter/pericenter flux ratio scales as 1+e for disk eccentricity e. We produce new models of this "apocenter glow" to explore its causes and wavelength dependence and study its potential as a probe of dust grain properties. Based on our models, we argue that several far-infrared and (sub)millimeter images of the Fomalhaut and epsilon Eridani debris rings obtained with Herschel, JCMT, SHARC II, ALMA, and ACTA should be reinterpreted as suggestions or examples of apocenter glow. This reinterpretation yields new constraints on the disks' dust grain properties and size distributions.

  16. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

  17. Heating rate effect on thermoluminescence glow curves of LiF:Mg,Cu,P+PTFE phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Zaragoza, E. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, Mexico D.F. 04510 (Mexico); Gonzalez, P.R., E-mail: pedro.gonzalez@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca S/N, C.P. 52750, Ocoyoacac, Estado de Mexico (Mexico); Azorin, J. [Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, 09340 Mexico D.F. (Mexico); Furetta, C. [Touro University Rome, Division of Touro College New York, Circne Gianicolense 15-17, 00153 Rome (Italy)

    2011-10-15

    The influence of heating rate on the thermoluminescence (TL) property of LiF:Mg,Cu,P+PTFE was analyzed. The activation energy and the frequency factor as a function of the heating rate were determined. The kinetic parameters and their dependence on the heating rate were evaluated using the sequential quadratic programming glow curve deconvolution (SQPGCD). The results showed that as the heating rate increases, the peak intensity at the maximum (I{sub M}) decreases and shifts to higher temperature; similar behavior of the kinetics parameters was observed. - Highlights: >Heating rate influence on the thermoluminescence (TL) property of LiF:Mg,Cu,P was analyzed. > The kinetic parameters, activation energy and frequency factor were evaluated using the sequential quadratic programming glow curve deconvolution. > The peak intensity at the maximum (I{sub M}) of the glow curves decreases. > Shifts to higher temperature were observed as the heating rate increased. > Similar behavior of the kinetics parameters was noticed.

  18. Raman spectroscopy system with hollow fiber probes

    Science.gov (United States)

    Liu, Bing-hong; Shi, Yi-Wei

    2012-11-01

    A Raman remote spectroscopy system was realized using flexible hollow optical fiber as laser emittion and signal collection probes. A silver-coated hollow fiber has low-loss property and flat transmission characteristics in the visible wavelength regions. Compared with conventional silica optical fiber, little background fluorescence noise was observed with optical fiber as the probe, which would be of great advantages to the detection in low frequency Raman shift region. The complex filtering and focusing system was thus unnecessary. The Raman spectra of CaCO3 and PE were obtained by using the system and a reasonable signal to noise ratio was attained without any lens. Experiments with probes made of conventional silica optical fibers were also conducted for comparisons. Furthermore, a silver-coated hollow glass waveguide was used as sample cell to detect liquid phase sample. We used a 6 cm-long hollow fiber as the liquid cell and Butt-couplings with emitting and collecting fibers. Experiment results show that the system obtained high signal to noise ratio because of the longer optical length between sample and laser light. We also give the elementary theoretical analysis for the hollow fiber sample cell. The parameters of the fiber which would affect the system were discussed. Hollow fiber has shown to be a potential fiber probe or sample cell for Raman spectroscopy.

  19. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    Science.gov (United States)

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  20. Study of the Effect of Decrease in the Conductivity Ahead of a Shock Wave in a Glow-Discharge Plasma

    Science.gov (United States)

    Baryshnikov, A. S.; Basargin, I. V.; Bobashev, S. V.; Monakhov, N. A.; Popov, P. A.; Sakharov, V. A.; Chistyakova, M. V.

    2016-05-01

    The electrical conductivity of a glow-discharge plasma ahead of a shock wave moving perpendicularly to the discharge axis has been investigated using a double electric probe. The obtained results have shown that the interaction of the shock wave with the glow-discharge plasma is accompanied by a change in its conductivity in the entire investigated volume simultaneously.

  1. Microfabrication of an anodic oxide film by anodizing laser-textured aluminium

    OpenAIRE

    2007-01-01

    A simple method for the fabrication of microstructures of an aluminium anodic oxide film (anodic alumina) by anodizing laser-textured aluminium is demonstrated. In the process, the aluminium substrate was first textured by a low power laser beam, and then the textured aluminium was subjected to anodizing, to develop a continuous, thick porous layer on the textured surface. Microstructures with a depth of a few to several tens of micrometres were fabricated successfully on the anodic oxide fil...

  2. Computational modeling of glow discharge-induced fluid dynamics

    Science.gov (United States)

    Jayaraman, Balaji

    Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow and operate as an actuator for flow control. The largely isothermal surface plasma generation realized above can modify the near-wall flow structure by means of Lorentzian collisions between the ionized fluid and the neutral fluid. Such an actuator has advantages of no moving parts, performance at atmospheric conditions and devising complex control strategies through the applied voltage. However, the mechanism of the momentum coupling between the plasma and the fluid flow is not yet adequately understood. In the present work, a modeling framework is presented to simulate athermal, non-equilibrium plasma discharges in conjunction with low Mach number fluid dynamics at atmospheric pressure. The plasma and fluid species are treated as a two-fluid system exhibiting a few decades of length and time scales. The effect of the plasma dynamics on the fluid dynamics is devised via a body force treatment in the Navier-Stokes equations. Two different approaches of different degrees of fidelity are presented for modeling the plasma dynamics. The first approach, a phenomenological model, is based on a linearized force distribution approximating the discharge structure, and utilizing experimental guidance to deduce the empirical constants. A high fidelity approach is to model the plasma dynamics in a self-consistent manner using a first principle-based hydrodynamic plasma model. The atmospheric pressure regime of interest here enables us to employ local equilibrium assumptions, signifying efficient collisional energy exchange as against thermal heating from inelastic collision processes. The time scale ratios between convection, diffusion, and reaction/ionization mechanisms are O(107), making the system computationally stiff. To handle the stiffness, a sequential finite-volume operator-splitting algorithm capable of conserving space charge is developed; the approach can handle time

  3. Thermoluminescence glow curve involving any extent of retrapping or any order of kinetics

    Indian Academy of Sciences (India)

    Jai Prakash

    2013-09-01

    Adirovitch set of equations has been modified to explain the mechanisms involved in thermoluminescence (TL) glow curve. A simple model is proposed which explains the occurrence of TL glow curve involving any extent of retrapping or any order of kinetics. It has been observed that the extents of recombination and simultaneous rewrapping decide the order of kinetics involved. TL decay parameters, order of kinetics and initial concentration of trapped electrons per unit volume are evaluated easily and conveniently. It has been observed that retrapping increases with increasing order of kinetics.

  4. Computerized glow curve deconvolution: the case of LiF TLD-100

    Energy Technology Data Exchange (ETDEWEB)

    Gartia, R.K.; Dorendrajit Singh, S.; Mazumdar, P.S. (Manipur Univ. (India). Dept. of Physics)

    1993-05-14

    It has been accepted by a large number of workers that the glow curve of LiF TLD (Thermoluminescent dosimetry)-100 can be described by thermoluminescence (TL) peaks following the Randall-Wilkins (RW) equation, even though the model fails to explain a number of experimental facts. A further simplification of the model is the Podgorsak-Moran-Cameron (PMC) approximation which is also in use. This paper points out the limitation of the PMC approximation in deconvoluting glow curves of LiF TLD-100. (author).

  5. 110° C thermoluminescence glow peak of quartz – A brief review

    Indian Academy of Sciences (India)

    D K Koul

    2008-12-01

    The 110°C glow peak of quartz, though unstable at room temperature, has worked wonderfully in archaeology and retrospective dosimetry due to its pre-dose sensitization property. Various aspects of the peak, like its nature, defect centres involved, the impact of different stimuli and its application have been extensively studied. The main aims of this review are to (i) summarize briefly the work carried out on the various facets of this TL glow peak during the last four decades and (ii) identify the areas which need further attention in order to have a better understanding of the luminescence characteristics of this TL peak.

  6. Short-term low-temperature glow discharge nitriding of 316L austenitic steel

    Directory of Open Access Journals (Sweden)

    T. Frączek

    2011-07-01

    Full Text Available The AISI 316L austenitic steel after glow discharge nitriding at temperature of T = 673 K and duration of τ=14,4 ks, for two different variants of specimen arrangement in the glow-discharge chamber was investigated. In order to assess the effectiveness of nitriding process, the surface layers profile analysis examination, surface hardness and hardness profile examination, the analysis of surface layer structures and corrosion resistance tests were performed. It has been found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel surface, what results in the surface layer thickness escalation.

  7. A study of glow-discharge and permeation techniques for extraterrestrial oxygen beneficiation

    Science.gov (United States)

    Ash, R. L.; Wu, D.; Outlaw, R. A.

    1994-01-01

    Extraction of oxygen from Martian atmosphere and compression of lunar oxygen can utilize stabilized zirconia electrochemical pumps. Silver membranes can be used as electrodes to increase oxygen yield at relatively low temperatures. This study has investigated oxygen permeation through Ag 0.05Zr membranes with glow-discharge assisted disassociation. Data show that the overall process is controlled by bulk diffusion but the slow dissociative adsorption onto the surface limited the overall transport substantially. With glow-discharge assisted dissociation, an order of magnitude increase in oxygen throughput can be produced at relatively low temperatures (450-550C).

  8. Does exclusion of protest zeros and warm-glow bidders cause selection bias in Contingent Valuation?

    DEFF Research Database (Denmark)

    Grammatikopoulou, Ioanna; Olsen, Søren Bøye; Pouta, Eija

    A great issue of concern in valuation studies is whether respondents provide trustworthy and reliable answers conditional on the perceived information. Respondent may report either a higher than the true Willingness-To-Pay (WTP) due to warm glow or embedding effects or zero WTP which is lower than...... the true WTP due to protest behavior. We conduct a contingent valuation study to estimate the WTP for conserving a Natura 2000 wetland area in Greece. We find that 54% of the positive bidders exert warm glow motivations while 29% of all responses can be classified as protest zero bids. We employ three...

  9. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    Science.gov (United States)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-12-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  10. Simultaneous analysis of the glow curves of thermoluminescence and thermally stimulated exo-electron emission

    CERN Document Server

    Sakurai, T; Fukuda, Y

    1999-01-01

    A new method to analyse the glow curves of thermoluminescence (TL) and thermally stimulated exo-electron emission (TSEE) simultaneously is proposed. The method is based on a model consisting of one trap-one recombination centre for TL and thermionic emission for TSEE. A set of coupled differential equations, describing the charge flow, is numerically solved without any approximation, using the integrated experimental glow curves, maximum conditions and boundary conditions of TL and TSEE. The computer simulation is carried out in the two following cases: the case of correlation between TL and TSEE; and the case of no correlation between TL and TSEE. (author)

  11. A STUDY OF THE POLYMERIZATION MECHANISM OF ACETONITRILE IN GLOW DISCHARGE

    Institute of Scientific and Technical Information of China (English)

    YU Qingsong; YE Mu; LU Lizhen; CHEN Jie; WANG Fosong; Yoshihito Osada

    1988-01-01

    Plasma polymerization of acetonitrile was carried out by a capacitively coupled RF plasma apparatus with external electrodes under some different reaction conditions such as discharge power. By investigating the informations provided by the polymer deposition regularities, IR spectra and elementary analysis results,the polymerization mechanism of acetonitrile in glow discharge have been investigated. The results show that acetonitrile polymerized in glow discharge mainly through hydrogen detachment for initiation at lower energy levels and the role that opening C = N triple bond played in polymerization became more important at higher energy levels.

  12. Research progress in the study of atmospheric pressure glow barrier discharge

    Institute of Scientific and Technical Information of China (English)

    LI Xuechen; DONG Lifang; JIA Pengying

    2007-01-01

    Atmospheric pressure glow barrier discharge (APGBD) can operate at high pressure, and so vacuum device is not necessary. Furthermore, the produced plasma by APGBD has moderate electron temperature and density besides good uniformity. Therefore,APGBD has extensive potential applications in industry and has been becoming a hot issue in the research of low temperature plasma. In this paper, the main problems in the study of atmospheric pressure glow discharge generated by dielectric barrier discharge, including the experimental setup, judging criterion, discharging conditions, physical mechanisms, and parameter diagnoses, are discussed, and further research prospects of APGBD are proposed.

  13. Characteristics of liquid flow induced by atmospheric-pressure DC glow discharge in contact with liquid

    Science.gov (United States)

    Tochikubo, Fumiyoshi; Aoki, Takuya; Shirai, Naoki; Uchida, Satoshi

    2017-04-01

    In this work, we investigated the characteristics of liquid flow induced by atmospheric-pressure dc glow discharge in contact with a liquid. The spatiotemporal development of liquid flow was visualized by the schlieren method, and the temperature distribution was measured using microencapsulated thermotropic liquid crystal particles dispersed in a liquid. We confirmed the appearance of specific downward liquid flow immediately below the dc glow discharge. The characteristics of downward liquid flow were reproduced by fluid simulation considering a downward driving force at the plasma–liquid interface. Our results suggest that the probable driving force for the downward liquid flow was the momentum transfer of charged species at the liquid surface.

  14. Anode sheath transition in an anodic arc for synthesis of nanomaterials

    Science.gov (United States)

    Nemchinsky, V. A.; Raitses, Y.

    2016-06-01

    The arc discharge with ablating anode or so-called anodic arc is widely used for synthesis of nanomaterials, including carbon nanotubes and fullerens, metal nanoparticles etc. We present the model of this arc, which confirms the existence of the two different modes of the arc operation with two different anode sheath regimes, namely, with negative anode sheath and with positive anode sheath. It was previously suggested that these regimes are associated with two different anode ablating modes—low ablation mode with constant ablation rate and the enhanced ablation mode (Fetterman et al 2008 Carbon 46 1322). The transition of the arc operation from low ablation mode to high ablation mode is determined by the current density at the anode. The model can be used to self-consistently determine the distribution of the electric field, electron density and electron temperature in the near-anode region of the arc discharge. Simulations of the carbon arc predict that for low arc ablating modes, the current is driven mainly by the electron diffusion to the anode. For positive anode sheath, the anode voltage is close to the ionization potential of anode material, while for negative anode sheath, the anode voltage is an order of magnitude smaller. It is also shown that the near-anode plasma, is far from the ionization equilibrium.

  15. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  16. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  17. Hollow cathode sustained plasma microjets: Characterization and application to diamond deposition

    Science.gov (United States)

    Sankaran, R. Mohan; Giapis, Konstantinos P.

    2002-09-01

    Extending the principle of operation of hollow cathode microdischarges to a tube geometry has allowed the formation of stable, high-pressure plasma microjets in a variety of gases including Ar, He, and H2. Direct current discharges are ignited between stainless steel capillary tubes (d=178 mum) which are operated as the cathode and a metal grid or plate that serves as the anode. Argon plasma microjets can be sustained in ambient air with plasma voltages as low as 260 V for cathode-anode gaps of 0.5 mm. At larger operating voltage, this gap can be extended up to several millimeters. Using a heated molybdenum substrate as the anode, plasma microjets in CH4/H2 mixtures have been used to deposit diamond crystals and polycrystalline films. Micro-Raman spectroscopy of these films shows mainly sp3 carbon content with slight shifting of the diamond peak due to internal stresses. Optical emission spectroscopy of the discharges used in the diamond growth experiments confirms the presence of atomic hydrogen and CH radicals.

  18. Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Rubio, M. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain); Ocon, P. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain)], E-mail: pilar.ocon@uam.es; Climent-Font, A. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Smith, R.W. [Unidad de Microanalisis de Materiales, Parque Cientifico de Madrid (PCM), Campus de Cantoblanco, 28049 Madrid (Spain); Curioni, M.; Thompson, G.E.; Skeldon, P. [Corrosion and Protection Centre, School of Materials, University of Manchester, M60 1QD England (United Kingdom); Lavia, A.; Garcia, I. [Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain)

    2009-09-15

    AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

  19. The thermoluminescence glow curve and the deconvoluted glow peak characteristics of erbium doped silica fiber exposed to 70-130 kVp x-rays.

    Science.gov (United States)

    Alawiah, A; Bauk, S; Marashdeh, M W; Nazura, M Z N; Abdul-Rashid, H A; Yusoff, Z; Gieszczyk, W; Noramaliza, M N; Adikan, F R Mahamd; Mahdiraji, G A; Tamchek, N; Muhd-Yassin, S Z; Mat-Sharif, K A; Zulkifli, M I; Omar, N; Wan Abdullah, W S; Bradley, D A

    2015-10-01

    In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.

  20. [Vernier Anode Design and Image Simulation].

    Science.gov (United States)

    Zhao, Ai-rong; Ni, Qi-liang; Song, Ke-fei

    2015-12-01

    Based-MCP position-sensitive anode photon-counting imaging detector is good at detecting extremely faint light, which includes micro-channel plate (MCP), position-sensitive anode and readout, and the performances of these detectors are mainly decided by the position-sensitive anode. As a charge division anode, Vernier anode using cyclically varying electrode areas which replaces the linearly varying electrodes of wedge-strip anode can get better resolution and greater electrode dynamic range. Simulation and design of the Vernier anode based on Vernier's decode principle are given here. Firstly, we introduce the decode and design principle of Vernier anode with nine electrodes in vector way, and get the design parameters which are the pitch, amplitude and the coarse wavelength of electrode. Secondly, we analyze the effect of every design parameters to the imaging of the detector. We simulate the electron cloud, the Vernier anode and the detector imaging using Labview software and get the relationship between the pitch and the coarse wavelength of the anode. Simultaneously, we get the corresponding electron cloud for the designing parameters. Based on the result of the simulation and the practical machining demand, a nine electrodes Vernier anode was designed and fabricated which has a pitch of 891 µm, insulation width of 25 µm, amplitude of 50 µm, coarse pixel numbers of 5.

  1. Electrocatalysis of carbon anode in aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The anodic overvoltage of the carbon anode in aluminum electrolysis isof the order of 0.6 V at normal current densities. However, it can be reduced somewhat by doping the anode carbon with various inorganic compounds. A new apparatus was designed to improve the precision of overvoltage measurements. Anodes were doped with MgAl2O4 and AlF3 both by impregnation of the coke and by adding powder, and the measured overvoltage was compared with that of undoped samples. For prebake type anodes baked at around 1150 oC, the anodic overvoltage was reduced by 40-60 mV, and for Soderberg type anodes, baked at 950 oC, by 60-80 mV.

  2. Hollow glass for insulating layers

    Science.gov (United States)

    Merticaru, Andreea R.; Moagar-Poladian, Gabriel

    1999-03-01

    Common porous materials, some of which will be considered in the chapters of this book, include concrete, paper, ceramics, clays, porous semiconductors, chromotography materials, and natural materials like coral, bone, sponges, rocks and shells. Porous materials can also be reactive, such as in charcoal gasification, acid rock dissolution, catalyst deactivation and concrete. This study continues the investigations about the properties of, so-called, hollow glass. In this paper is presented a computer simulation approach in which the thermo-mechanical behavior of a 3D microstructure is directly computed. In this paper a computer modeling approach of porous glass is presented. One way to test the accuracy of the reconstructed microstructures is to computed their physical properties and compare to experimental measurement on equivalent systems. In this view, we imagine a new type of porous type of glass designed as buffer layer in multilayered printed boards in ICs. Our glass is a variable material with a variable pore size and surface area. The porosity could be tailored early from the deposition phases that permitting us to keep in a reasonable balance the dielectric constant and thermal conductivity.

  3. Effects of Anode Wettability and Slots on Anodic Bubble Behavior Using Transparent Aluminium Electrolytic Cells

    Science.gov (United States)

    Zhao, Zhibin; Gao, Bingliang; Feng, Yuqing; Huang, Yipeng; Wang, Zhaowen; Shi, Zhongning; Hu, Xianwei

    2017-02-01

    Transparent aluminum electrolytic cells were used to study the effects of anode wettability and slots on bubble behavior in a similar environment to that used in industrial cells. Observations were conducted using two types of transparent cells, one with side-observation and the other with a bottom-observation cell design. Anodic bubbles rising process in the side channel is strongly affected by the wettability of the anode. After rising a short distance, the bubbles detach from the anode vertical surface at good-wetting anode cases, while the bubbles still attach to the vertical surface at poor-wetting anode cases. Anode slots of width of 4 mm are able to prevent smaller bubbles from coalescing into larger bubbles and thus decrease the bubble size and gas coverage on the anode. Anode slots also make a contribution in slightly reducing bubble thickness. With the presence of slots, the bubble-induced cell voltage oscillation decreases as well.

  4. Fabrication and anodic polarization behavior of lead-based porous anodes in zinc electrowinning

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new type of lead-based porous anode in zinc electrowinning was prepared by negative pressure infiltration.The anodie polarization potential and corrosion rate were studied and compared with those of traditional fiat anodes (Pb-0.8%Ag) used in industry.The anode eorrosion rate was determined by anode actual current density and microstructure.The results show that the anodic oxygen evolution potential decreases first and then increases with the decrease of pore diameter.The anodic potential decreases to the lowest value of 1.729 V at the pore diameter of 1.25-1.60 mm.The porous anode can decrease its actual current density and thus decrease the anodic corrosion rate.When the pore diameter is 1.60-2.00 mm,the anodic relative corrosion rate reaches the lowest value of 52.1%.

  5. Template-free synthesis of hierarchical TiO2 hollow microspheres as scattering layer for dye-sensitized solar cells

    Science.gov (United States)

    Rui, Yichuan; Wang, Linlin; Zhao, Jiachang; Wang, Hongzhi; Li, Yaogang; Zhang, Qinghong; Xu, Jingli

    2016-04-01

    Hierarchical TiO2 hollow microspheres were synthesized by a 2-step process consisting of thermal hydrolysis and subsequent solvothermal reaction. Quasi-monodispersed solid TiO2 microspheres aggregated by amorphous particles were firstly obtained by the controlled thermal hydrolysis of titanium sulfate, and then the solid structures transformed to hollow ones and crystallized during the subsequent solvothermal treatment. SEM and TEM images of the samples revealed that the morphological evolution was in perfect accordance with the inside-out Ostwald ripening mechanism. The rich porosity and unique hierarchical hollow structure endow the TiO2 microspheres with a large specific surface area of 108.0 m2 g-1. As an effective anode material for dye-sensitized solar cells, TiO2 hollow microspheres showed good capability of dye adsorption and strong light scattering, leading to a comparable energy conversion efficiency to the commercial 18NR-T transparent titania. Finally, a high efficiency of 7.84% was achieved for the bi-layer DSSC by coating the hollow microspheres on top of the 18NR-T titania as the light scattering layer.

  6. Controllable fabrication of urchin-like Co3O4 hollow spheres for high-performance supercapacitors and lithium-ion batteries.

    Science.gov (United States)

    Chen, Fashen; Liu, Xiaohe; Zhang, Zhian; Zhang, Ning; Pan, Anqiang; Liang, Shuquan; Ma, Renzhi

    2016-09-27

    Urchin-like cobalt oxide (Co3O4) hollow spheres can be successfully prepared by thermal decomposition of cobalt carbonate hydroxide hydrate (Co(CO3)0.5(OH)·0.11H2O) obtained by template-assisted hydrothermal synthesis. The morphology, crystal structure evolution and thermal decomposition behaviors of the as-prepared products have been carefully investigated. A plausible formation mechanism of the urchin-like Co3O4 hollow spheres in the presence of hexadecyl trimethyl ammonium bromide (CTAB) as the surfactant template is proposed. The urchin-like Co3O4 hollow spheres are further constructed as electrode materials for high-performance supercapacitors with a high specific capacitance of 460 F g(-1) at a current density of 4 A g(-1) and excellent cycling stability. Furthermore, as anode materials for lithium-ion batteries (LIBs), superior lithium storage performance of 1342.2 mA h g(-1) (0.1 C) and 1122.7 mA h g(-1) (0.2 C) can also be achieved. The excellent performances can be ascribed to the unique hierarchical urchin-like hollow structure of the electrode materials, which offers a large specific surface area, short electron and ion diffusion paths and high permeability while being directly in contact with the electrolyte. Moreover, the hollow structure with sufficient internal void spaces can self-accommodate volume change during electrochemical reactions, which improves the structural stability and integrity.

  7. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    Science.gov (United States)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-12-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

  8. Endotoxin removal by radio frequency gas plasma (glow discharge)

    Science.gov (United States)

    Poon, Angela

    2011-12-01

    Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were

  9. Evaluation of trapping parameter of quartz by deconvolution of the glow curves

    Energy Technology Data Exchange (ETDEWEB)

    Gartia, R.K. [Department of Physics, Manipur University, Imphal 795001 (India); Singh, L. Lovedy, E-mail: lovedyo1@yahoo.co.in [Department of Physics, Manipur University, Imphal 795001 (India)

    2011-08-15

    The glow curves of natural quartz excited with different doses of {beta}-irradiation have been subjected to Computerized Glow Curve Deconvolution (CGCD) in the kinetic formalism. The location of the constituent peaks, which are as many as eleven in the temperature region of 27-575 deg. C, has been ascertained by resorting to the second order derivative plot of the glow curve. Not only figure of merit (FOM) but {chi}{sup 2}-test has also been taken as a criterion for the acceptance of goodness of fit. CGCD analysis reveals that the frequency factor of quartz is in the range of 1.50 {+-} 0.26 x 10{sup 11} sec{sup -1}. This analysis lead to the conclusion that the trapping levels of quartz can be approximated by the Urbach's relation E = 27kT{sub m} where T{sub m} is the temperature at the maximum intensity. - Highlights: > Glow curves of natural and beta-irradiated quartz in the temperature range from room temperature to 573 deg. C is analysed. > Frequency factor of quartz is in the range of 1.50 {+-} 0.26 x 10{sup 11} sec{sup -1}. > Trapping levels of quartz can be approximated by the Urbach's relation E = 27kT{sub m}.

  10. The multisensor payload 'Structura' for the observation of atmospheric night glows from the ISS board

    Science.gov (United States)

    Krot, Yury; Beliaev, Boris; Katkovsky, Leonid

    2016-10-01

    Aerospace Research Department of the Institute of Applied Physical Problems at Belarusian State University has developed a prototype of the optical payload intended for a space experiment on the ISS board. The prototype includes four optical modules for the night glows observation, in particular spatial-brightness and spectral characteristics in the altitude range of 80-320 km. Objects of the interest are emitting top layers of the atmosphere including exited OH radicals, atomic and molecular oxygen and sodium layers. The goal of the space experiment is a research of night glows over different regions of the Earth and a connection with natural disasters like earthquakes, cyclones, etc. Two optical modules for spatial distribution of atomic oxygen layers along the altitude consist of input lenses, spectral interferential filters and line CCD detectors. The optical module for registration of exited OH radical emissions is formed from CCD array spectrometer. The payload includes also a panchromatic (400-900 nm) high sensitive imaging camera for observing of the glows general picture. The optical modules of the prototype have been tested and general optical characteristics were determined in laboratory conditions. A solution of an astigmatism reducing of a concave diffraction grating and a method of the second diffraction order correction were applied and improved spectrometer's optical characteristics. Laboratory equipment and software were developed to imitate a dynamic scene of the night glows in laboratory conditions including an imitation of linear spectra and the spatial distribution of emissions.

  11. Drift-diffusion model of normal glow discharge in an axial magnetic field

    Science.gov (United States)

    Surzhikov, S. T.

    2016-12-01

    A two-dimensional axisymmetrical computing model is formulated with using of which the mathematical modeling of the normal glow discharge in molecular hydrogen is fulfilled in an axial magnetic field with the induction B = 0.1 T in the pressure range p = 1.25-5 Torr and the current-source electromotive force E = 1-3 kV.

  12. An efficient model to simulate stable glow corona discharges and their transition into streamers

    Science.gov (United States)

    Liu, Lipeng; Becerra, Marley

    2017-03-01

    A computationally efficient model to evaluate stable glow corona discharges and their transition into streamers is proposed. The simplified physical model referred to as the SPM is based on the classic hydrodynamic model of charge particles and a quasi-steady state approximation for electrons. The solution follows a two-step segregated procedure, which solves sequentially the stationary continuity equation for electrons and then time-dependent continuity equations for ions. The validity of using the SPM to simulate glow corona discharges and their transition into streamers is demonstrated by performing comparisons with a fully coupled physical model (FPM) and with experimental data available in the literature for air under atmospheric conditions. It is shown that the SPM can obtain estimates similar to those calculated with the FPM and those measured in experiments but using significantly less computation time. Since the proposed model simulates efficiently the ionization layer without prior knowledge of the surface electric field or the discharge current, it is a computationally efficient alternative to calculations of glow corona discharges based on Kaptzov’s approximation (KAM). The model can also be employed to efficiently calculate the conditions for the transition of glow corona into streamers, overcoming the limitations of KAM to provide such estimates.

  13. Qualitative gas temperature distribution in positive DC glow corona using spectral image processing in atmospheric air

    Science.gov (United States)

    Matsumoto, Takao; Inada, Yoichi; Shimizu, Daisuke; Izawa, Yasuji; Nishijima, Kiyoto

    2015-01-01

    An experimental method of determining a qualitative two-dimensional image of the gas temperature in stationary atmospheric nonthermal plasma by spectral image processing was presented. In the experiment, a steady-state glow corona discharge was generated by applying a positive DC voltage to a rod-plane electrode in synthetic air. The changes in the gas temperature distribution due to the amplitude of applied voltage and the ambient gas pressure were investigated. Spectral images of a positive DC glow corona were taken using a gated ICCD camera with ultranarrow band-pass filters, corresponding to the head and tail of a N2 second positive system band (0-2). The qualitative gas temperature was obtained from the emission intensity ratio between the head and tail of the N2 second positive system band (0-2). From the results, we confirmed that the gas temperature and its distribution of a positive DC glow corona increased with increasing applied voltage. In particular, just before the sparkover voltage, a distinctly high temperature region was formed in the positive DC glow at the tip of the rod electrode. In addition, the gas temperature decreased and its distribution spread diffusely with decreasing ambient gas pressure.

  14. Quantitative Analysis on Carbon Migration in Double-Glow Discharge Plasma Surface Alloying Process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-xia; WANG Cong-zeng; ZHANG Wen-quan; SU Xue-kuan

    2004-01-01

    Carbon migration is of great significance in double-glow discharge plasma surface alloying process, but literature of quantitative analysis about carbon migration is relatively scarce. In this paper differential equations of the carbon and metal concentration distribution were established. By means of differential equations carbon migration was described and a numerical solution was acquired. The computational results fit the experiment results quite well.

  15. Accounting protesting and warm glow bidding in Contingent Valuation surveys considering the management of environmental goods

    DEFF Research Database (Denmark)

    Grammatikopoulou, Ioanna; Olsen, Søren Bøye

    2013-01-01

    Based on a Contingent Valuation survey aiming to reveal the willingness to pay (WTP) for conservation of a wetland area in Greece, we show how protest and warm glow motives can be taken into account when modeling WTP. In a sample of more than 300 respondents, we find that 54% of the positive bids...

  16. A Study on Water Treatment Induced by Plasma with Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    胡中爱; 王晓艳; 高锦章; 邓华陵; 侯经国; 卢小泉; 康敬万

    2001-01-01

    Oxidative degradation of eight kinds of dyes induced by plasma in aqueous solution was investigated with contact glow discharge electrolysis (CGDE). It has been demonstrated that these eight dyes underwent degradation in CGDE, where Fe2+ could be utilised to raise the efficiency of degradation of dyes.

  17. Preparation of hollow spherical carbon nanocages

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.-K.; Kang, H. Y.; Hong, C.-I; Huang, C.-H.; Chang, F.-C.; Wang, H. Paul, E-mail: wanghp@mail.ncku.edu.tw [National Cheng Kung University, Department of Environmental Engineering, Taiwan (China)

    2012-12-15

    This study presents a new and simple method for the synthesis of hollow carbon spheres possessing nanocage sizes of 7.1, 14, and 20 nm in diameter. The core-shell (i.e., Cu-C) nanoparticles prepared by carbonization of the Cu{sup 2+}-cyclodextrin (CD) complexes at 573 K for 2 h was etched with HCl (6N) to yield the hollow carbon spheres. The carbon-shell of the hollow carbon nanospheres, which consisted of mainly diamond-like and graphite carbons, is not perturbed during etching. In addition to the nanocages, the hollow carbon nanospheres also possess micropores with an opening of 0.45 nm, allowing small molecules to diffuse in and out through the carbon-shell. Many elements (such as Zn{sup 2+} or Cu{sup 2+}) can therefore be filled into the nanocages of the hollow carbon nanospheres. With these unique properties, for instance, designable active species such as Cu and ZnO encapsulated in the carbon-shell can act as Cu-ZnO-C yolk-shell nanoreactors which are found very effective in the catalytic decomposition of methanol.

  18. Method for the production of fabricated hollow microspheroids

    Energy Technology Data Exchange (ETDEWEB)

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  19. Modification of SnO2 Anodes by Atomic Layer Deposition for High Performance Lithium Ion Batteries

    KAUST Repository

    Yesibolati, Nulati

    2013-05-01

    Tin dioxide (SnO2) is considered one of the most promising anode materials for Lithium ion batteries (LIBs), due to its large theoretical capacity and natural abundance. However, its low electronic/ionic conductivities, large volume change during lithiation/delithiation and agglomeration prevent it from further commercial applications. In this thesis, we investigate modified SnO2 as a high energy density anode material for LIBs. Specifically two approaches are presented to improve battery performances. Firstly, SnO2 electrochemical performances were improved by surface modification using Atomic Layer Deposition (ALD). Ultrathin Al2O3 or HfO2 were coated on SnO2 electrodes. It was found that electrochemical performances had been enhanced after ALD deposition. In a second approach, we implemented a layer-by-layer (LBL) assembled graphene/carbon-coated hollow SnO2 spheres as anode material for LIBs. Our results indicated that the LBL assembled electrodes had high reversible lithium storage capacities even at high current densities. These superior electrochemical performances are attributed to the enhanced electronic conductivity and effective lithium diffusion, because of the interconnected graphene/carbon networks among nanoparticles of the hollow SnO2 spheres.

  20. Anodic polarographic determination of flucloxacillin.

    Science.gov (United States)

    Squella, J A; Silva, M M; Nuñez-Vergara, L J

    1981-11-01

    The hydrolysis of flucloxacillin at pH 4.9 yields a degradation product which is polarographically oxidizable. This derivative has not been identified, but would seem to contain a thiol group. It gives a diffusion-controlled anodic polarographic wave with a half-wave potential at -0.24 V vs. SCE. The method developed has been applied to the analysis of flucloxacillin capsules, and a recovery of 99% has been obtained.

  1. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  2. Reactions on carbon anodes in aluminium electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Eidet, Trygve

    1997-12-31

    The consumption of carbon anodes and energy in aluminium electrolysis is higher than what is required theoretically. This thesis studies the most important of the reactions that consume anode materials. These reactions are the electrochemical anode reaction and the airburn and carboxy reactions. The first part of the thesis deals with the kinetics and mechanism of the electrochemical anode reaction using electrochemical impedance spectroscopy. The second part deals with air and carboxy reactivity of carbon anodes and studies the effects of inorganic impurities on the reactivity of carbon anodes in the aluminium industry. Special attention is given to sulphur since its effect on the carbon gasification is not well understood. Sulphur is always present in anodes, and it is expected that the sulphur content of available anode cokes will increase in the future. It has also been suggested that sulphur poisons catalyzing impurities in the anodes. Other impurities that were investigated are iron, nickel and vanadium, which are common impurities in anodes which have been reported to catalyze carbon gasification. 88 refs., 92 figs., 24 tabs.

  3. Characterization of Light at Night Data from Select SkyGlowNet Nodes

    Science.gov (United States)

    Flurchick, K. M.; Deal, S.; Foster, C.

    2013-05-01

    Internet-enabled sky brightness meters (iSBMs) that continuously record and log sky brightness at the zenith have been installed at the prototype nodes of a network called SkyGlowNet. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. Although the SkyGlowNetdata are used for various professional scientific studies, they are also useful for independent student research projects. In this case, the data are uploaded to the SkyGlowNetwebsite, initially to a proprietary area where the data for each institution are embargoed for one or two semesters as students conduct research projects with their data. When released from embargo, the data are moved to another area where they can be accessed by all SkyGlowNet participants. In this paper, we describe a student project in which the data collected at two SkyGlowNet sites are characterized. The data streams are parsed into homogenous segments and statistical tools are employed to describe variations observed in the data values. We demonstrate how to differentiate between natural phenomena and the effects of artificial lighting on the brightness of the night sky. In our poster we show how these effects compare between sites as separate as Arizona and North Carolina. We also have experimented with the development of statistical metrics that are used to help categorize sky brightness on select nights, and can nearly automatically provide a characterization of the quality of the night sky for astronomical purposes.

  4. How does the Warm Breeze affect the heliospheric backscatter glow of interstellar neutral helium?

    Science.gov (United States)

    Bzowski, Maciej; Kubiak, Marzena; Sokół, Justyna

    2017-04-01

    Based on direct sampling observations of interstellar neutral helium (ISN He) by IBEX, we have discovered a new population of ISN He, dubbed the Warm Breeze (WB), and identified it as the secondary population of ISN He, created in the outer heliosheath. The WB flow is twice slower and hotter by half than the primary ISN He, and it flows from a direction different by 5° in longitude and 6° in latitude. Its density is 5% of that of ISN He. ISN He had been extensively studied in the past by analysis of the backscatter glow, but the WB was not considered in these analyses because its existence had been unknown. However, the ISN He speed and temperature derived from analyses of the heliospheric helium glow tended to be systematically biased towards slower speeds or higher temperatures with respect to those obtained from direct-sampling experiments. We calculate the expected intensity of the backscatter glow due to the ISN He and WB using the best-fit parameters recently obtained from IBEX direct-sampling observations and compare its distribution in the sky with that expected only from the primary ISN gas. In the modeling, we use a time-dependent hot model of Maxwell-Boltzmann distribution of ISN gas and carefully account for the bulk velocities and temperatures of the direct and indirect beams of the two populations, as well as for details of the ionization rates. We discuss differences between intensities of the backscatter glow expected from different regions in the sky, obtained for the models including and excluding the WB and point out that the absence of the WB component in the modeling may have biased the parameters of the primary population of ISN He derived from the helium backscatter glow and lead to underestimating the Mach number of the flow, due to a slower bulk speed or higher temperature.

  5. Fabrication by Co-extrusion and electrochemical characterization of micro-tubular hollow fibre solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Droushiotis, Nicolas; Doraswami, Uttam; Othman, Mohd Hafiz Dzarfan; Li, Kang; Kelsall, Geoff [Department of Chemical Engineering, Imperial College London, London SW7 2AZ (United Kingdom); Ivey, Douglas [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta (Canada)

    2010-06-15

    A phase inversion process was used to co-extrude cerium-gadolinium oxide (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95})/NiO-CGO dual-layer hollow fibres (HF), which were then sintered to form, respectively, the electrolyte and high porosity anode precursor of a solid oxide fuel cell (SOFC) with anode inner diameter of 0.8 mm. Graded CGO-lanthanum strontium cobalt ferrite (La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Co{sub 0.2}O{sub 3}) cathode layers were then painted onto the CGO electrolyte to form a micro-tubular HF-SOFC. With a carefully designed anode current collector, this produced maximum power densities of 1186-5864 W m{sup -} {sup 2} at 450-570 C. High magnification imaging analysis revealed large three-phase boundary regions within the anode, a dense electrolyte layer and clearly highlighted the multiple CGO-LSCF cermet and pure LSCF cathode layers. The performance of the HF-SOFC with a twenty millimetre active length showed no degradation after four thermal cycles between 300 C and 570 C. (author)

  6. Pulse dispersion in hollow optical waveguides

    Science.gov (United States)

    Ben-David, M.; Ilev, Ilko K.; Waynant, Ronald W.; Gannot, Israel

    2005-09-01

    A study of laser (near- and mid-infrared) pulse dispersion in hollow waveguides is presented. We developed an analytical model to describe the pulse dispersion in hollow waveguides and compared our theoretical calculations with measurements done by us and also by two other groups. The pulse dispersion was experimentally measured for a short Q-switched Er:YAG laser in the nanosecond range and for femtosecond Ti:sapphire laser pulses transmitted by hollow optical waveguides. For analytical calculation of the pulse dispersion in these waveguides, a refined ray tracing program was developed. This approach took into account roughness of the internal reflecting and refracting inner layers. A comparison analysis between the measurements and calculations conducted at identical parameters demonstrates good correlation between theoretical and experimental results.

  7. Hollow glass waveguides for broadband infrared transmission.

    Science.gov (United States)

    Abel, T; Hirsch, J; Harrington, J A

    1994-07-15

    Broadband hollow glass waveguides have been fabricated with losses as low as 0.15 dB/m at 10.6 microm. We make these hollow glass waveguides by coating the inside of polyimide-coated silica-glass tubing with a metallic layer followed by a thin dielectric coating of a metal halide. The bore sizes of the guides range from 320 to 700 microm, and we have made lengths as long as 3 m. The bending radii of the waveguides are less than 5 cm for bore sizes less than 500 microm. We have used these waveguides to deliver greater than 80 W of CO(2) laser power and 5 W of Er:YAG laser power. The hollow glass guides are inexpensive, robust, and quite flexible and therefore a good infrared fiber for power and sensor applications.

  8. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  9. Generation of a hollow laser beam by a multimode fiber

    Institute of Scientific and Technical Information of China (English)

    Hongyu Ma; Huadong Cheng; Wenzhuo Zhang; Liang Liu; Yuzhu Wang

    2007-01-01

    A simple method to generate a hollow laser beam by multimode fiber is reported. A dark hollow laser beam is generated from a multimode fiber and the dependence of the output beam profile on the incident angle of laser beam is analyzed. The results show that this hollow laser beam can be used to trap and guide cold atoms.

  10. Self-ordered nanopore arrays through hard anodization assisted by anode temperature ramp

    Science.gov (United States)

    Mohammadniaei, M.; Maleki, K.; Kashi, M. Almasi; Ramezani, A.; Mayamei, Y.

    2016-10-01

    In the present work, hard anodization assisted by anode temperature ramp was employed to fabricate self-ordered nanoporous alumina in the wide range of interpore distances (259-405 nm) in pure oxalic acid and mixture of oxalic and phosphoric acid solutions. Anode temperature ramp technique was employed to adjust the anodization current density to optimize the self-ordering of the nanopore arrays in the interpore range in which no ordered self-assembled hard anodized anodic aluminum oxide has reported. It is found that the certain ratios of oxalic and phosphoric acid solutions in this anodization technique increased self-ordering of the nanopores especially for anodization voltages over the 170 V by increasing alumina's viscous flow which could lead to decrease the overall current density of anodization, yet leveled up by anode temperature ramp. However, below 150 V anodization voltage, the ratio of interpore distance to the anodization voltage of the both anodization techniques was the same (~2 nm/V), while above this voltage, it increased to about 2.2 nm/V.

  11. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  12. Hollow electrode loose plate SOFC design

    Energy Technology Data Exchange (ETDEWEB)

    Jaspers, B.C.; Dongen, B.A.M. van; Monaster, G.A. [Seed Capital Investments B.V., Utrecht (Netherlands); Roosmalen, J.A.M. van; Plaisier, K.H.; Schoonman, J. [Delft Univ. of Technology (Netherlands). Lab. for Applied Inorganic Chemistry

    1995-12-31

    A novel planar SOFC design is presented, based on the loose stacking of hollow electrode elements, conventional plate type electrolytes and interconnectors. This facilitates free thermal expansion during operation, and thermal cycling, thereby significantly improving prospects for reliable SOFC operation in power generation practice. Each individual element only consists of one material, eliminating the need for sealing and for matching thermal expansion coefficients of fuel cell components. Application of hollow electrodes results in an inherent manifolding of the gas streams eliminating the need for seals at the fuel cell stack itself. The design has been tested at laboratory scale and a small working prototype fuel cell has been successfully tested.

  13. Scaffold Characteristics for Functional Hollow Organ Regeneration

    Directory of Open Access Journals (Sweden)

    Daniel Eberli

    2010-01-01

    Full Text Available Many medical conditions require surgical reconstruction of hollow organs. Tissue engineering of organs and tissues is a promising new technique without harvest site morbidity. An ideal biomaterial should be biocompatible, support tissue formation and provide adequate structural support. It should degrade gradually and provide an environment allowing for cell-cell interaction, adhesion, proliferation, migration, and differentiation. Although tissue formation is feasible, functionality has never been demonstrated. Mainly the lack of proper innervation and vascularisation are hindering contractility and normal function. In this chapter we critically review the current state of engineering hollow organs with a special focus on innervation and vascularisation.

  14. Composition dependence of glow peak temperature in KCl{sub 1-x}Br{sub x} doped with divalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Salas, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); Aceves, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); RodrIguez-Mijangos, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); Riveros, H G [Instituto de FIsica, UNAM, Apartado Postal 20/364, Mexico, DF 01000, Mexico (Mexico); Duarte, C [Departamento de GeologIa, Universidad de Sonora, Rosales y Boulevard Luis E, Hermosillo, Sonora, 83000 (Mexico)

    2004-01-28

    Thermoluminescence measurements of {beta}-irradiated Eu{sup 2+} - and Ca{sup 2+} - doped KCl{sub 1-x}KBr{sub x} solid solutions excited at room temperature have been carried out to identify the effect of composition on the glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. These results indicate that for divalent impurity-doped alkali halide solid solutions these glow peak temperatures are mostly dependent on the lattice constant of the host than on the size of the anion or impurity cation.

  15. Development of open-air type electrolyte-as-cathode glow discharge-atomic emission spectrometry for determination of trace metals in water

    Science.gov (United States)

    Kim, Hyo J.; Lee, Jeong H.; Kim, Myung Y.; Cserfalvi, T.; Mezei, P.

    2000-07-01

    The open-air type electrolyte cathode atomic glow discharge (ELCAD) has been developed and studied for fundamental and analytical applications for determination of trace heavy metals in water. The normal closed-type discharge cell shows some problems such as unstable plasma due to changes in the pressure inside the cell during the discharge, and water vapor condensing onto the window. Applying approximately 1500 V to the several-millimeter gap between the electrolyte solution cathode and a Pt rod anode in atmospheric air pressure produced a stable plasma and significantly improved sensitivity. The emission spectrum of de-ionized water containing 100 mg/l Cu was measured and some emission lines were found from Cu I (324.7 nm, 327.4 nm and 510.5 nm) and Cu II (224.7 nm and 229.4 nm). The LODs of Cr, Cu, Fe, Mn, Ni, Pb, and Zn are in the ranges from 0.01 mg/l to 0.6 mg/l. The LODs of Cu, Mn, Pb and Zn improve by approximately one order of magnitude compared to the previous closed-type ELCAD.

  16. New anodizing process for magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    LUO Sheng-lian; DAI Lei; ZHOU Hai-hui; CHAI Li-yuan; KUANG Ya-fei

    2006-01-01

    Compact anodic films with high hardness and good corrosion resistance on magnesium alloys were prepared by a new constant voltage and arc-free anodizing process. The effects of anodizing parameters such as applied voltage and electrolyte temperature on the peak current density and the thickness of films were investigated. In addition, the morphologies and corrosion resistance of films were investigated by scanning electron microscopy and potentiodynamic polarization, respectively. The results show that the higher the applied voltage, the higher the peak current density and the thicker the films. However, too high applied voltage may result in breakdown of films and intense sparking which may deteriorate the properties of the anodic films and bring about unsafety. The new anodizing process can be applied in a wide range of temperature. The new anodic films have numbers of pores with the diameter of 0.5 - 5.0 μm which do not transverse the entire film.

  17. Structural engineering of nanoporous anodic aluminium oxide by pulse anodization of aluminium.

    Science.gov (United States)

    Lee, Woo; Schwirn, Kathrin; Steinhart, Martin; Pippel, Eckhard; Scholz, Roland; Gösele, Ulrich

    2008-04-01

    Nanoporous anodic aluminium oxide has traditionally been made in one of two ways: mild anodization or hard anodization. The first method produces self-ordered pore structures, but it is slow and only works for a narrow range of processing conditions; the second method, which is widely used in the aluminium industry, is faster, but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the mild and hard anodization processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic aluminium oxide films while maintaining high throughput. We use pulse anodization to delaminate a single as-prepared anodic film into a stack of well-defined nanoporous alumina membrane sheets, and also to fabricate novel three-dimensional nanostructures.

  18. The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?

    Directory of Open Access Journals (Sweden)

    Aki Tsuruhara

    2011-06-01

    Full Text Available We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.

  19. Anodizing And Sealing Aluminum In Nonchromated Solutions

    Science.gov (United States)

    Emmons, John R.; Kallenborn, Kelli J.

    1995-01-01

    Improved process for anodizing and sealing aluminum involves use of 5 volume percent sulfuric acid in water as anodizing solution, and 1.5 to 2.0 volume percent nickel acetate in water as sealing solution. Replaces process in which sulfuric acid used at concentrations of 10 to 20 percent. Improved process yields thinner coats offering resistance to corrosion, fatigue life, and alloy-to-alloy consistency equal to or superior to those of anodized coats produced with chromated solutions.

  20. Anodic Materials for Electrocatalytic Ozone Generation

    Directory of Open Access Journals (Sweden)

    Yun-Hai Wang

    2013-01-01

    Full Text Available Ozone has wide applications in various fields. Electrocatalytic ozone generation technology as an alternative method to produce ozone is attractive. Anodic materials have significant effect on the ozone generation efficiency. The research progress on anodic materials for electrocatalytic ozone generation including the cell configuration and mechanism is addressed in this review. The lead dioxide and nickel-antimony-doped tin dioxide anode materials are introduced in detail, including their structure, property, and preparation. Advantages and disadvantages of different anode materials are also discussed.

  1. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Zheng WenJun

    2009-01-01

    Full Text Available Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  2. Template engaged synthesis of hollow ceria-based composites

    Science.gov (United States)

    Chen, Guozhu; Rosei, Federico; Ma, Dongling

    2015-03-01

    Hollow ceria-based composites, which consist of noble metal nanoparticles or metal oxides as a secondary component, are being studied extensively for potential applications in heterogeneous catalysis. This is due to their unique features, which exhibit the advantages of a hollow structure (e.g. high surface area and low weight), and also integrate the properties of ceria and noble metals/metal oxides. More importantly, the synergistic effect between constituents in hollow ceria-based composites has been demonstrated in various catalytic reactions. In this feature article, we summarize the state-of-the-art in the synthesis of hollow ceria-based composites, including traditional hard-templates and more recently, sacrificial-template engaged strategies, highlighting the key role of selected templates in the formation of hollow composites. In addition, the catalytic applications of hollow ceria-based composites are briefly surveyed. Finally, challenges and perspectives on future advances of hollow ceria-based composites are outlined.

  3. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...... is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible...

  4. Hollow-atom probing of surfaces

    NARCIS (Netherlands)

    Limburg, J.

    1997-01-01

    This paper discusses the mechanisms governing the formation and decay of hollow atoms in front of (semi) conducting and insulating surfaces. First, the primary neutralization of the highly charged ions is treated in terms of the classical overbarrier model. Different views are presented. Then the mo

  5. Galvanic Synthesis of Hollow Gold Nanoshells

    Science.gov (United States)

    2015-02-01

    pulses in the NIR.2 The advantage of hollow nanoshells over solid gold (Au) or silver (Ag) nanoparticles , or alloys thereof,3 is that the...Karna SP. Synthesis of gold and silver nanoparticles and characterization of structural, optical, and electronic properties. Aberdeen Proving Ground...

  6. Development of On-Line Direct Current Glow Discharge Source for Analysis of Isotope Ratio of Hydrogen

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The present research is focused on the analysis of isotope ratio of the hydrogen by measuring an intensity ratio of hydrogen/deuterium/tritium fluxes. The direct current glow discharge tube may provide a

  7. Anodically bonded submicron microfluidic chambers.

    Science.gov (United States)

    Dimov, S; Bennett, R G; Córcoles, A; Levitin, L V; Ilic, B; Verbridge, S S; Saunders, J; Casey, A; Parpia, J M

    2010-01-01

    We demonstrate the use of anodic bonding to fabricate cells with characteristic size as large as 7 x 10 mm(2), with height of approximately 640 nm, and without any internal support structure. The cells were fabricated from Hoya SD-2 glass and silicon wafers, each with 3 mm thickness to maintain dimensional stability under internal pressure. Bonding was carried out at 350 degrees C and 450 V with an electrode structure that excluded the electric field from the open region. We detail fabrication and characterization steps and also discuss the design of the fill line for access to the cavity.

  8. Anodically bonded submicron microfluidic chambers

    Science.gov (United States)

    Dimov, S.; Bennett, R. G.; Córcoles, A.; Levitin, L. V.; Ilic, B.; Verbridge, S. S.; Saunders, J.; Casey, A.; Parpia, J. M.

    2010-01-01

    We demonstrate the use of anodic bonding to fabricate cells with characteristic size as large as 7×10 mm2, with height of ≈640 nm, and without any internal support structure. The cells were fabricated from Hoya SD-2 glass and silicon wafers, each with 3 mm thickness to maintain dimensional stability under internal pressure. Bonding was carried out at 350 °C and 450 V with an electrode structure that excluded the electric field from the open region. We detail fabrication and characterization steps and also discuss the design of the fill line for access to the cavity.

  9. Anodization process produces opaque, reflective coatings on aluminum

    Science.gov (United States)

    1965-01-01

    Opaque, reflective coatings are produced on aluminum articles by an anodizing process wherein the anodizing bath contains an aqueous dispersion of finely divided insoluble inorganic compounds. These particles appear as uniformly distributed occlusions in the anodic deposit on the aluminum.

  10. Acceleration of deuterons with suppression of electronic conductance in a vacuum diode with a laser target on the anode

    Science.gov (United States)

    Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Shatokhin, V. L.

    2016-12-01

    We report new experimental results on the acceleration of deuterons in a compact coaxial diode with the suppression of electronic conductance by a constant longitudinal magnetic field. Plasma containing deuterons is created on a laser TiD target located on the anode. The pulse of accelerating voltage is formed by means of the Arkad'ev-Marx generator. The cathode symmetrically surrounds the anode and comprises a hollow permanent ring magnet with an inner radius of no more than 0.02 m and an on-axis induction of up to 0.4 T, which provides the magnetic insulation of the accelerating gap. The experiments demonstrate the possibility of obtaining accelerated deuterons with energy of up to 300 keV and a current of up to 0.5 kA with a pulse duration of 0.2 μs.

  11. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    OpenAIRE

    Pai, David,; Lacoste, Deanna,; Laux, C.

    2010-01-01

    International audience; In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determine...

  12. Glow curves and the emission of flux-grown BaFCl:Na crystals. [X radiation and gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Hari Babu, V. (Osmania Univ., Hyderabad (India). Dept. of Physics)

    1984-08-01

    The thermoluminescence glow curves and the emission spectra of flux-grown BaFCl:Na crystals were recorded. An additional TL peak at 320 K, an optical absorption band at 570nm and an emission peak at 490 nm have been seen in X/..gamma..-irradiated crystals. Bleaching, room-temperature annealing and high-temperature emission results led us to conclude that the sodium impurity is responsible for the additional glow peak optical absorption band and emission peak.

  13. Isotope effects on desorption kinetics of hydrogen isotopes implanted into stainless steel by glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, M.; Kondo, M.; Noda, N. [Hydrogen Isotope Research Center, University of Toyama, Gofuku, Toyama (Japan); Tanaka, M.; Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu (Japan)

    2015-03-15

    In a fusion device the control of fuel particles implies to know the desorption rate of hydrogen isotopes by the plasma-facing materials. In this paper desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by experiment and numerical calculation. The temperature of a maximum desorption rate depends on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions have been successfully reproduced by numerical simulations that are based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel is limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms. (authors)

  14. Fading prediction in thermoluminescent materials using computerised glow curve deconvolution (CGCD)

    CERN Document Server

    Furetta, C; Weng, P S

    1999-01-01

    The fading of three different thermoluminescent (TL) materials, CaF sub 2 : Tm (TLD-300), manocrystalline LiF : Mg,Ti (DTG-4) and MgB sub 4 O sub 7 : Dy,Na has been studied at room temperature and at 50 deg. C of storage. The evolution as a function of the elapsed time of the whole glow curve as well as of the individual peaks has been analysed using the Computerised Glow Curve Deconvolution (CGCD) program developed at the NTHU. The analysis allows to predict the loss of the dosimetric information and to make any correction is necessary for using the TL dosimeters in practical applications. Furthermore, it is well demonstrated that using CGCD it is not necessary to anneal the peaks having a rapid fading to avoid, then, any interfering effect on the more stable peaks.

  15. Canard-induced mixed mode oscillations in an excitable glow discharge plasmas

    CERN Document Server

    Nurujjaman, M

    2014-01-01

    We demonstrated experimentally canard induced mixed mode oscillations (MMO) in an excitable glow discharge plasma, and the results are validated through numerical solution of the FitzHugh Nagumo (FHN) model. When glow discharge plasma is perturbed by applying a magnetic field, it shows mixed mode oscillatory activity, i.e., quasiperiodic small oscillations interposed with large bounded limit cycles oscillations. The initial quasiperiodic oscillations were observed to change into large amplitude limit cycle oscillations with magnetic field, and the number of these oscillation increases with increase in the magnetic field. Fourier analysis of both numerical and experimental results show that the origin of these oscillations are canard-induced phenomena, which occurs near the threshold of the control parameter. Further, the phase space plots also confirm that the oscillations are basically canard-induced MMOs.

  16. Optimal length of capacitive-discharge and glow-discharge excilamps

    Science.gov (United States)

    Boichenko, A. M.; Erofeev, M. V.; Sosnin, E. A.; Tarasenko, V. F.; Yakovlenko, S. I.

    2007-06-01

    The optimal tube length of capacitive-discharge and glow-discharge excimer lamps with ring and circular electrodes of equal radii is considered. It is demonstrated that, at the same potential difference between electrodes and their radii, the ratio of the optimal lengths of the tubes with circular and ring electrodes depends on width L of the ring electrodes. The ratio of the lengths decreases with decreasing L. A relationship between the tube length and radius, the width of ring electrodes, and the minimum voltage at the tube that provide for an approximately uniform glow of the discharge column in the presence of voltage pulses with opposite polarities at the electrodes is derived.

  17. Polarity functions' characterization and the mechanism of starch modification by DC glow discharge plasma.

    Science.gov (United States)

    Khorram, S; Zakerhamidi, M S; Karimzadeh, Z

    2015-01-01

    The wheat starch was investigated, before and after exposure to the argon and oxygen glow discharge plasma, without any added chemical reagents, using a novel media polarity functions method. The mechanisms of modification of starch in plasma discharge irradiation were explained using some methods such as; NMR, IR spectroscopy, Kamlet-Abboud-Taft polarity functions (specific and nonspecific interaction) of modified starch. The starch modification, by plasma treatment, shows valuable changes with plasma gas and relative ionized or active species. Characterizations indicate that argon glow discharge plasma increases crosslink in C-2 site of starch. Also, oxygen plasma discharge irradiation tends to oxidize the OH group in C-6 site of carbonyl group. Furthermore, the reported mechanisms show the highest efficiency, because of the stereo-chemical orientation of active sites of starch and plasma potential of wall in plasma media. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Evidence for large-area superemission into a high-current glow discharge

    Science.gov (United States)

    Hartmann, W.; Dominic, V.; Kirkman, G. F.; Gundersen, M. A.

    1988-10-01

    This letter presents evidence for large-area (≊1 cm2) cathode superemission (˜10 000 A/cm2) into a high-current glow discharge in a pseudospark or back lighted thyratron switch. Cathodes studied with a scannning electron microscope following operation at 6-8 kA, ≊1 μs pulse length, and 105 pulses in a low-pressure H2 discharge show evidence of melting of a thin surface layer within a radius of ˜4 mm, indicating that the discharge is a superdense glow with a cross-sectional area of the order of 1 cm2, rather than an arc. Further supporting evidence is provided by streak camera data. An ion beam present during the avalanche phase of the discharge is responsible for heating the cathode surface resulting in a significant field-enhanced thermionic emission.

  19. Chaotic-to-ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas

    Indian Academy of Sciences (India)

    Md Nurujjaman; A N Sekar Iyengar

    2006-08-01

    Transition from chaotic to ordered state has been observed during the initial stage of a discharge in a cylindrical DC glow discharge plasma. Initially it shows a chaotic behavior but increasing the discharge voltage changes the characteristics of the discharge glow and shows a period subtraction of order 7 period → 5 period → 3 period → 1 period, i.e. the system goes to single mode through odd cycle subtraction. On further increasing the discharge voltage, the system goes through period doubling, like 1 period → 2 period → 4 period. On further increasing the voltage, the system goes to stable state through two period subtraction, like 4 period → 2 period → stable.

  20. Double Glow Plasma Hydrogen-free Carburizing on Commercial Purity Titanium

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaohui; PAN Junde; HE Zhiyong; ZHANG Pingze; GAO Yuan; XU Zhong

    2005-01-01

    A carburized layer with special physical and chemical properties was formed on the surface of commercial purity titanium by a double glow plasma hydrogen-free carburizing technique. High-purity netlike solid graphite was used as a raw material and commercial purity titanium was used as the substrate material. Argon gas was used as the working gas. The carburized layer can be obviously observed under a microscope. X-ray diffraction indicates that TiC phase with higher hardness and dissociate state carbon phase was formed in the carburized layer. The glow discharge spectrum (GDS) analysis shows that the carbon concentration distributes gradiently along the depth of carburized layer. The surface hardness of the substrate increases obviously. The hardness distributes gradiently from the surface to inner of carburized layer. The friction coefficient reduces by more than 1/2, the ratio wear rate decreases by above three orders of magnitude. The wear resistance of the substrate material is improved consumedly.

  1. Model of control of glow discharge electron gun current for microelectronics production applications

    Science.gov (United States)

    Denbnovetsky, S. V.; Melnyk, V. I.; Melnyk, I. V.; Tugay, B. A.

    2003-04-01

    The problems of simulation of discharge current control and its gas-dynamic stabilization for technological glow discharge electron guns with a cold cathode are considered in a paper. Such guns are successfully operated in soft vacuum and can be used in modern microelectronic technologies for providing of thermal operations with using different technological gases including active ones. The results of theoretical and experimental investigation of automatic control system of current of electron gun which were used for deposition of coatings in reactive gas medium are presented in article. Time of regulation for considered system did not exceed 400 ms. Is proved, that the automatic control of a current of a glow discharge electron gun by pressure variation its volume is effective on all operation range of pressure, and the minimum time of a current regulation can be tens -- hundred of ms, and this fact is allow to use in the majority of technological operations for microelectronic production.

  2. SkyGlowNet: Multi-Disciplinary Independent Student Research in Environmental Light at Night Monitoring

    Science.gov (United States)

    Craine, B. L.; Craine, E. R.; Culver, R. B.; DeBenedetti, J. C.; Flurchick, K. M.

    2014-07-01

    SkyGlowNet uses Internet-enabled sky brightness meters (iSBM) to monitor sky brightness over school sites. The data are used professionally and in STEM outreach to study natural and artificial sources of sky brightness, light pollution, energy efficiency, and environmental and health impacts of artificial night lighting. The iSBM units are owned by participating institutions and managed by faculty or students via proprietary Internet links. Student data are embargoed for two semesters to allow students to analyze data and publish results, then they are moved to a common area where students from different institutions can collaborate. The iSBM units can be set to operate automatically each night. Their data include time, sky brightness, weather conditions, and other related parameters. The data stream can be viewed and processed online or downloaded for study. SkyGlowNet is a unique, multi-disciplinary, real science program aiding research for science and non-science students.

  3. Hardness and stress of amorphous carbon film deposited by glow discharge and ion beam assisting deposition

    CERN Document Server

    Marques, F C

    2000-01-01

    The hardness and stress of amorphous carbon films prepared by glow discharge and by ion beam assisting deposition are investigated. Relatively hard and almost stress free amorphous carbon films were deposited by the glow discharge technique. On the other hand, by using the ion beam assisting deposition, hard films were also obtained with a stress of the same order of those found in tetrahedral amorphous carbon films. A structural analysis indicates that all films are composed of a sp sup 2 -rich network. These results contradict the currently accepted concept that both stress and hardness are only related to the concentration of sp sup 3 sites. Furthermore, the same results also indicate that the sp sup 2 sites may also contribute to the hardness of the films.

  4. Determination of the cathode layer thickness in the normal glow discharge

    Science.gov (United States)

    Hou, Xinyu; Fu, Yangyang; Wang, Hao; Zou, Xiaobing; Luo, Haiyun; Wang, Xinxin

    2017-08-01

    Two methods for the determination of the cathode layer thickness dn in the normal glow discharge were developed. The first one is the computational method based on the iteration with a differently assumed value of dn. The second one is the experimental method with a Langmuir probe. The computational results showed that the reduced cathode layer thickness p.dn monotonically decreases and finally saturates with the increase in the cathode fall. It was found with these two methods that p.dn is a constant for the given cathode fall and secondary electron emission coefficient. This implies that the cathode layer will automatically adjust its thickness to keep p.dn a constant when the gas pressure changes. The results obtained with these two developed methods were compared with the results obtained with the numerical simulation of the normal glow discharge, which shows a good agreement.

  5. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    Science.gov (United States)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-05-01

    In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow regime at a given gas temperature. We derive a criterion for the existence of the NRP glow regime as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.

  6. The glow duration time influence on the ionization rate detected in the diodes filled with noble gases on mbar pressures

    Directory of Open Access Journals (Sweden)

    Stepanović Olivera M.

    2003-01-01

    Full Text Available The results of the glow current duration time (glowing-time influence on the ionization rate detected in the gas filled diodes are presented. The electrical breakdown was detected as the minimal current impulse. After that diode glow from the minimal glowing-time (10-3 s, up to the maximal 103 s which overlap the time of the stationary regime formation in the gas diode tube. The diodes were with volumes of 300 cm3, but with a diode gap volume of about 1 cm3 and filled with helium, neon, argon or krypton, at the pressures of the order of mbar. The ionization rates were detected as the residual ionization after the glowing was interrupted, using the electrical breakdown time delay measuring method. The influence of the gap distance stationary current values and the relaxation period were also investigated. The result shows that the stationary regime in such a gas diode is established after the glowing time of 1-3 s, although the breakdown formative times were smaller then 1 ms.

  7. General Approach for MOF-Derived Porous Spinel AFe2O4 Hollow Structures and Their Superior Lithium Storage Properties.

    Science.gov (United States)

    Yu, Hong; Fan, Haosen; Yadian, Boluo; Tan, Huiteng; Liu, Weiling; Hng, Huey Hoon; Huang, Yizhong; Yan, Qingyu

    2015-12-09

    A general and simple approach for large-scale synthesis of porous hollow spinel AFe2O4 nanoarchitectures via metal organic framework self-sacrificial template strategy is proposed. By employing this method, we can successfully synthesize uniform NiFe2O4, ZnFe2O4, and CoFe2O4 hollow architectures that are hierarchically assembled by nanoparticles. When these hollow microcubes were tested as anode for lithium ion batteries, good rate capability and long-term cycling stability can be achieved. For example, high specific capacities of 636, 449, and 380 mA h g(-1) were depicted by NiFe2O4, ZnFe2O4, and CoFe2O4, respectively, at a high current density of 8.0 A g(-1). NiFe2O4 exhibits high specific capacities of 841 and 447 mA h g(-1) during the 100th cycle when it was tested at current densities of 1.0 and 5.0 A g(-1), respectively. Discharge capacities of 390 and 290 mA h g(-1) were delivered by the ZnFe2O4 and CoFe2O4, respectively, during the 100th cycle at 5.0 A g(-1).

  8. General synthesis of vanadium-based mixed metal oxides hollow nanofibers for high performance lithium-ion batteries

    Science.gov (United States)

    Xiang, Juan; Yu, Xin-Yao; Paik, Ungyu

    2016-10-01

    Hollow nanostructured mixed metal oxides have recently been intensively investigated as electrode materials for energy storage and conversion due to their remarkable electrochemical properties. Although great efforts have been made, the synthesis of hollow nanostructured vanadium-based mixed metal oxides especially those with one dimensional structure is rarely reported. Vanadium-based mixed metal oxides are promising electrode materials for lithium-ion batteries with high capacity and good rate capability. Here, we develop a facile and general method for the synthesis of one dimensional MxV2O8 (M = Co, Ni, Fe) tubular structure through a simple single-spinneret electrospinning technique followed by a calcination process. As a demonstration, Co3V2O8 hollow nanofibers are evaluated as anode materials for lithium-ion batteries. As expected, benefiting from their unique one dimensional tubular structure, the as-synthesized Co3V2O8 exhibits excellent electrochemical properties for lithium storage. To be specific, it can deliver a high specific capacity of 900 mAh g-1 at 5 A g-1, and long cycling stability up to 2000 cycles. The present work makes a significant contribution to the design and synthesis of mixed metal oxides with one dimensional tubular structure, as well as their potential applications in electrochemical energy storage.

  9. A Monte Carlo Simulation for the Ion Transport in Glow Discharges with Dusts

    Institute of Scientific and Technical Information of China (English)

    SUN Ai-Ping; PU Wei; QIU Xiao-Ming

    2001-01-01

    We use the Monte Carlo method to simulate theion transport in the rf parallel plate glow discharge with a negative-voltage pulse connected to the electrode. It is found that self-consistent field, dust charge, dust concentration,and dust size influence the energy distribution and the density of the ions arriving at the target, and in particular, the latter two make significant influence. As dust concentration or dust size increases, the number of ions arriving at the target reduces greatly.

  10. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2013-01-01

    Full Text Available To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g increased significantly than that of pure carbon nanotubes (6.7 F/g.

  11. The nature of glow arising in PETN monocrystals’ explosion initiated by a pulsed electron beam

    Science.gov (United States)

    Aduev, B. P.; Belokurov, G. M.; Grechin, S. S.; Liskov, I. Yu; Kalenskii, A. V.; Zvekov, A. A.

    2015-04-01

    The explosive decomposition of pentaerythritol tetranitrate monocrystals under the influence of a high-current electron beam (0.25 MeV, 20 ns, 15 J/cm2) was researched with the approach of high temporal resolution optic spectroscopy. We measured kinetics and emission spectra in real time scale. The thermal nature of the explosive glow was proven with the method of spectral pyrometry. The estimated temperature of the explosion is T ≈ 3000 K..

  12. Effect of Atmospheric Pressure Glow Discharge Treatment on Polymerization of Acrylic Fabric and Its Printing Behavior

    Directory of Open Access Journals (Sweden)

    D M El-Zeer

    2014-03-01

    Full Text Available Acrylic fibers have been treated by atmospheric pressure glow discharge (APGD plasma in open air to enhance surface antistatic properties. The treated surfaces are investigated by scanning electron microscopy (SEM, Fourier-Transition Infrared Spectroscopy (FTIR and Atomic Force Microscope (AFM. Plasma treatment of acrylic fabric has been found to increase the surface roughness, modify the nature and density of surface functionalities, and drastically improve the wettability and antistatic ability of acrylic fibers.

  13. Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

    Science.gov (United States)

    Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

    2014-12-01

    The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films.

  14. Increased chondrocyte adhesion on nanotubular anodized titanium.

    Science.gov (United States)

    Burns, Kevin; Yao, Chang; Webster, Thomas J

    2009-03-01

    Previous studies have demonstrated increased osteoblast (bone-forming cells) functions (including adhesion, synthesis of intracellular collagen, alkaline phosphatase activity, and deposition of calcium-containing minerals) on titanium anodized to possess nanometer features compared with their unanodized counterparts. Such titanium materials were anodized to possess novel nanotubes also capable of drug delivery. Since titanium has not only experienced wide spread commercial use in orthopedic but also in cartilage applications, the objective of the present in vitro study was for the first time to investigate chondrocyte (cartilage synthesizing cells) functions on titanium anodized to possess nanotubes. For this purpose, titanium was anodized in dilute hydrofluoric acid at 20 V for 20 min. Results showed increased chondrocyte adhesion on anodized titanium with nanotube structures compared with unanodized titanium. Importantly, the present study also provided evidence why. Since material characterization studies revealed significantly greater nanometer roughness and similar chemistry as well as crystallinity between nanotubular anodized and unanodized titanium, the results of the present study highlight the importance of the nanometer roughness provided by anodized nanotubes on titanium for enhancing chondrocyte adhesion. In this manner, the results of the present in vitro study indicated that anodization might be a promising quick and inexpensive method to modify the surface of titanium-based implants to induce better chondrocyte adhesion for cartilage applications.

  15. LITHIUM ANODE LIMITED CYCLE SECONDARY BATTERY

    Science.gov (United States)

    aluminum resist corrosion in these solutions. Polyolefin and polyester nonwoven fabrics may be used as separators. Li anodes in propylene carbonate...ization. Electrode test results were used to design, construct and test cells with Li anodes and CuF2 cathodes.

  16. Numerical simulation of a direct current glow discharge in atmospheric pressure helium

    Science.gov (United States)

    Yin, Zeng-Qian; Wang, Yan; Zhang, Pan-Pan; Zhang, Qi; Li, Xue-Chen

    2016-12-01

    Characteristics of a direct current (DC) discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage-current characteristics. Project supported by the National Natural Science Foundation of China (Grant Nos. 11575050 and 10805013), the Midwest Universities Comprehensive Strength Promotion Project, the Natural Science Foundation of Hebei Province, China (Grant Nos. A2016201042 and A2015201092), and the Research Foundation of Education Bureau of Hebei Province, China (Grant No. LJRC011).

  17. Slow electron energy balance for hybrid models of direct-current glow discharges

    Science.gov (United States)

    Eliseev, S. I.; Bogdanov, E. A.; Kudryavtsev, A. A.

    2017-09-01

    In this paper, we present the formulation of slow electron energy balance for hybrid models of direct current (DC) glow discharge. Electrons originating from non-local ionization (secondary) contribute significantly to the energy balance of slow electrons. An approach towards calculating effective energy brought by a secondary electron to the group of slow electrons by means of Coulomb collisions is suggested. The value of effective energy shows a considerable dependence on external parameters of a discharge, such as gas pressure, type, and geometric parameters. The slow electron energy balance was implemented into a simple hybrid model that uses analytical formulation for the description of non-local ionization by fast electrons. Simulations of short (without positive column) DC glow discharge in argon are carried out for a range of gas pressures. Comparison with experimental data showed generally good agreement in terms of current-voltage characteristics, electron density, and electron temperature. Simulations also capture the trend of increasing electron density with decreasing pressure observed in the experiment. Analysis shows that for considered conditions, the product of maximum electron density ne and electron temperature Te in negative glow is independent of gas pressure and depends on the gas type, cathode material, and discharge current. Decreasing gas pressure reduces the heating rate of slow electrons during Coulomb collisions with secondary electrons, which leads to lower values of Te and, in turn, higher maximum ne.

  18. FT Tokamak Upgrade (FTU) vacuum vessel section cleaning by glow discharge in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ciotti, M.; Apicella, M.L.; Verdini, L.; Ferro, C.

    1991-09-01

    The possibility of applying glow discharge in hydrogen for the cleaning of the FTU (Frascati Tokamak Upgrade) vacuum chamber was analyzed on a 1:1 scale toroidal section by using the same operating conditions as foreseen for the machine. The discharge was maintained for six hours in the chamber with the wall temperature kept at 150 degrees C. The partial pressures at the end of the cleaning run were compared with those obtained by using only thermal outgassing at the same temperature. A reduction of about a factor of two in the H/sub 2/0 and C0/sub 2/ partial pressures was observed, related to a better cleanness of the surface. It was found that the high temperature during the glow discharge cleaning not only increases the efficiency of the discharge, but it is an efficient tool to remove impurities from the hidden regions, defined by the thermal shields that cover all the vacuum vessel walls not directly exposed to the glow discharge.

  19. Development and synthesis of durable self-glowing crystals doped with plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Burakov, B.E. [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 2nd Site, 1, Rentgena Street, St. Petersburg 197101 (Russian Federation); Domracheva, Ya.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya Street, St. Petersburg 194021 (Russian Federation)], E-mail: y.domracheva@mail.ioffe.ru; Zamoryanskaya, M.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya Street, St. Petersburg 194021 (Russian Federation); Petrova, M.A.; Garbuzov, V.M.; Kitsay, A.A.; Zirlin, V.A. [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 2nd Site, 1, Rentgena Street, St. Petersburg 197101 (Russian Federation)

    2009-03-15

    Different crystalline materials doped with plutonium and other alpha-emitting radionuclides are characterized by self-glowing. Some of these materials, in particular, monocrystalline ones, which are highly chemically resistant, mechanically durable, and stable under radiation damage are promising for application in optical couplers, robotics and medicine. They might be used for a long time (from tens to hundreds years) in aggressive chemical media and space. Crystals with low content of radionuclides (less than 0.1 wt%) but intensive self-glowing are main subject of interest. Phosphate and silicate single crystals with zircon structure: xenotime, (Y,...)PO{sub 4} and zircon, (Zr,...)SiO{sub 4}, were doped with {sup 238}Pu, {sup 237}Np and non-radioactive elements: Eu{sup 3+}; In{sup 3+} and Tb{sup 3+}. The most intensive self-glowing was obtained for xenotime crystals doped with 0.1 wt% {sup 238}Pu and Eu; and for zircon crystals doped with 0.01 wt% {sup 238}Pu and coupled admixture of In and Tb.

  20. Quantification Approach of Gas Temperate Distribution in Atmospheric Positive DC Glow Discharge Measured by Spectroscopic Imaging

    Science.gov (United States)

    Sasamoto, Ryo; Orii, Hideaki; Matsumoto, Takao; Izawa, Yasuji; Nishijima, Kiyoto

    2015-09-01

    In our previous work, a two-dimensional (2D) gas temperature distribution in a positive DC steady-state glow corona was qualitatively measured by spectroscopic imaging. Spectral images of its glow corona were taken using ICCD camera with ultra-narrow band-pass filters, and they were corresponded to the head and tail of a second positive system bands of nitrogen (2PS N2 (0-2)). The qualitative gas temperature was obtained from the emission intensity ratio (I2 Ptail/I2 Phead) between the head and tail of 2PS N2 (0-2). This emission intensity ratio also equals the rotational temperature (TR) , and TR almost equals the gas temperature (TG) in atmospheric pressure. In this work, the qualitative 2D gas temperature distribution was derived from 2D I2 Ptail/I2 Phead plots, and the calibration date of I2 Ptail/I2 Phead for TR was accumulated by investigating the relationship between the spatially average absolute gas temperature (Tav) obtained by single-point spectroscopic measurement and the average value of I2 Ptail/I2 Phead plots. On the basis of the calibration date, a spectroscopically-imaged qualitative 2D I2 Ptail/I2 Phead distribution in a positive DC glow corona was converted to a quantitative 2D image of gas rotational temperature.

  1. Methane Conversion to C2 Hydrocarbons by Abnormal Glow Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    Dai Wei; Yu Hui; Chen Qi; Yin Yongxiang; Dai Xiaoyan

    2005-01-01

    Methane conversion to C2 hydrocarbons has been investigated with the addition of hydrogen in a plasma reactor of abnormal glow discharge at atmospheric pressure. The aim of this experiment is to minimize coke formation and improve discharge stability. The typical conditions in the experiment are 300 ml of total feed flux and 400 W of discharge power. The experimental results show that methane conversion is from 91.6% to 35.2% in mol, acetylene selectivity is from 90.2% to 57.6%, and ethylene selectivity is approximately from 7.8% to 3.6%,where the coke increases gradually along with the increase of CH4/H2 from 2: 8 to 9: 1. A stable discharge for a considerable running time can be obtained only at a lower ratio of CH4/H2= 2:8 or 3: 7. These phenomena indicate that the coke deposition during methane conversion is obviously reduced by adding a large amount of hydrogen during an abnormal glow discharge.A qualitative interpretation is presented, namely, with abundant hydrogen, the possibility that hydrogen molecules are activated to hydrogen radicals is increased with the help of the abnormal glow discharge. These hydrogen radicals react with carbon radicals to form C2 hydrocarbon products. Therefore, the deposition of coke is restrained.

  2. Micro glow plasma for localized nanostructural modification of carbon nanotube forest

    Science.gov (United States)

    Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer; Nojeh, Alireza; Takahata, Kenichi

    2016-08-01

    This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ˜30% and ˜300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

  3. Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge

    Indian Academy of Sciences (India)

    Raju Bhai Tyata; Deepak Prasad Subedi; Rajendra Shrestha; Chiow San Wong

    2013-03-01

    In this paper, atmospheric pressure glow discharges (APGD) in argon generated in parallel plate dielectric barrier discharge system is investigated by means of electrical and optical measurements. Using a high voltage (0–20 kV) power supply operating at 10–30 kHz, homogeneous and steady APGD has been observed between the electrodes with gap spacing from 0.5 mm to 2 mm and with a dielectric barrier of thickness 2 mm while argon gas is fed at a controlled flow rate of 11/min. The electron temperature and electron density of the plasma are determined by means of optical emission spectroscopy. Our results show that the electron density of the discharge obtained is of the order of 1016 cm-3 while the electron temperature is estimated to be 0.65 eV. The important result is that electron density determined from the line intensity ratio method and stark broadening method are in very good agreement. The Lissajous figure is used to estimate the energy deposited to the glow discharge. It is found that the energy deposited to the discharge is in the range of 20 to 25 $\\$J with a discharge voltage of 1.85 kV. The energy deposited to the discharge is observed to be higher at smaller gas spacing. The glow discharge plasma is tested to be effective in reducing the hydrophobicity of polyethylene film significantly.

  4. Characteristics of Left-Right Spiral Hollow Cylindrical Roller

    Institute of Scientific and Technical Information of China (English)

    Liming Lu; Qiping Chen; Yujiang Qin

    2015-01-01

    Based on new rolling⁃sliding compound bearings, the wear between the one⁃way spiral hollow cylindrical roller and the ribs of the inner and outer ring of rolling⁃sliding compound bearings is reduced by innovational structural design. A new left⁃right spiral hollow cylindrical roller is proposed to replace the one⁃way spiral hollow cylindrical roller. The finite element analysis models of ordinary cylindrical rollers, one⁃way spiral hollow cylindrical rollers and left⁃right spiral hollow cylindrical rollers are respectively established by ABAQUS. The axial displacement of their center mass and the stress distribution of left⁃right spiral hollow cylindrical rollers are compared and analyzed. Theoretical study results show that this new left⁃right spiral hollow cylindrical roller not only inherits the advantages of one⁃way spiral hollow cylindrical rollers, but also avoids the axial offset and the serious wear of the one⁃way spiral hollow cylindrical roller. And the theory research conclusion is verified by the experiment. The left⁃right spiral hollow cylindrical roller has the advantages to overcome boundary stress concentration like logarithmic convex roller. The rolling⁃sliding compound bearings equipped with the new rollers can be better to adapt to the impact of vibration load.

  5. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  6. Hierarchical hollow Fe2O3@MIL-101(Fe)/C derived from metal-organic frameworks for superior sodium storage

    Science.gov (United States)

    Li, Chengping; Hu, Qian; Li, Yan; Zhou, Hang; Lv, Zhaolin; Yang, Xiangjun; Liu, Lixiang; Guo, Hong

    2016-05-01

    A facile generic template-free strategy is employed to prepare hierarchical hollow hybrid Fe2O3@MIL-101(Fe)/C materials derived from metal-organic frameworks as anode materials for Na-ion batteries. The intrinsic hollow nanostructure can shorten the lengths for both electronic and ionic transport, enlarge the surface areas of electrodes, and improve accommodation of the volume change during Na+ insertion/extraction cycling. Therefore, The stable reversible capacity of Fe2O3@MIL-101(Fe)/C electrode is 710 mAhg‑1, and can be retained at 662 mAhg‑1 after 200 cycles with the retention of 93.2%. Especially, its overall rate performance data confirm again the importance of the hierarchical hollow structures and multi-elements characteristics toward high capacities in both low and high current rates. This general strategy may shed light on a new avenue for fast synthesis of hierarchic hollow functional materials for energy storage, catalyst, sensor and other new applications.

  7. Template-free formation of carbon nanotube-supported cobalt sulfide@carbon hollow nanoparticles for stable and fast sodium ion storage

    Science.gov (United States)

    Han, Fei; Jun Tan, Clara Yi; Gao, Zhiqiang

    2017-01-01

    Carbon-coated cobalt sulfide (CoS) hollow nanoparticles on carbon nanotube (CNT) networks are synthesized by combining three simple approaches: direct growth of Co3O4 nanocrystals on the CNT backbones, chemical conversion of the Co3O4 nanocrystals to CoS hollow nanoparticles, and the spatial introduction of conformal surface modification by carbon. It is noteworthy that the CoS hollow nanoparticles with inner cavity of <50 nm and an average wall thickness of 6-8 nm are derived from a template-free method. Such a template-free-derived multifunctional nanostructure design achieves the amalgamation of the favorite traits of one-dimensional conducting networks, hollow nanoparticles, and surface modification, thus resulting in much enhanced charge transfer, ion transport, and upholding the integrity of the electrode and electrode/electrolyte interface. When applied the synthesized CoS-based material as anodes in sodium-ion batteries (SIBs), excellent performance is observed. For instance, a reversible specific capacity of 562 mAh g-1 at 100 mA g-1 and a capacity retention rate of 90% after 200 cycles at a higher current density of 500 mA g-1 are obtained. Moreover, a superior rate capability is observed with reversible specific capacities of 341 and 276 mAh g-1 at 2000 and at 5000 mA g-1, respectively.

  8. Hollow antiresonant fibers with reduced attenuation.

    Science.gov (United States)

    Belardi, Walter; Knight, Jonathan C

    2014-04-01

    An improved design for hollow antiresonant fibers (HAFs) is presented. It consists of adding extra antiresonant glass elements within the air cladding region of an antiresonant hollow-core fiber. We use numerical simulations to compare fiber structures with and without the additional cladding elements in the near- and mid-IR regimes. We show that realizable fiber structures can provide greatly improved performance in terms of leakage and bending losses compared to previously reported antiresonant fibers. At mid-IR wavelengths, the adoption of this novel fiber design will lead to HAFs with reduced bending losses. In the near-IR, this design could lead to the fabrication of HAFs with very low attenuation.

  9. Experimental evaluation of a hollow glass fiber.

    Science.gov (United States)

    Bornstein, A; Croitoru, N

    1986-02-01

    Very high interest in making a low-loss fiber for the infrared has been stimulated by important applications in optical communication, surgery, cutting, welding, and heat treatment. The leaky waveguide is one of the most promising types of future fiber in the infrared region where low-loss materials are not available or not suitable for making fibers (i.e., CO2 laser light lambda = 10.6 microm). In this paper a comparative model of a He-Ne laser beam and an oxide glass leaky hollow fiber for a CO2 laser light beam and a chalcogenide glass leaky hollow fiber are studied. Measurements of attenuation, dependence of output power on diameter and angle, and the angular dependence of output angle vs input angle were made. The experimental data were compared with theoretical calculations, and the critical value of the wall thickness for minimum attenuation is given.

  10. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  11. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  12. Characterizing the elasticity of hollow metal nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ji Changjiang; Park, Harold S [Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235 (United States)

    2007-03-21

    We have performed atomistic simulations on solid and hollow copper nanowires to quantify the elastic properties of hollow nanowires (nanoboxes). We analyse variations in the modulus, yield stress and strain for <100> and <110> nanoboxes by varying the amount of bulk material that is removed to create the nanoboxes. We find that, while <100> nanoboxes show no improvement in elastic properties as compared to solid <100>nanowires, <110> nanoboxes can show enhanced elastic properties as compared to solid <110> nanowires. The simulations reveal that the elastic properties of the nanoboxes are strongly dependent on the relative strength of the bulk material that has been removed, as well as the total surface area of the nanoboxes, and indicate the potential of ultralight, high-strength nanomaterials such as nanoboxes.

  13. The Nitrogen-Nitride Anode.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  14. Hollow Sucker Rod Applied in Production Engineering

    Institute of Scientific and Technical Information of China (English)

    Wang Tongbin; Liu Liandong; Hu Daoming; Jia Yanshan

    1997-01-01

    @@ Working Principle A positive cycle system or a working channel can be formed by means of hollow sucker rod and its mating parts in the oil tube ofa well, through which heat carriers (such as hot water,hot oil and steam), chemicals and heating cable can be pumped or put into the well so as to lower the viscosity of crude, dissolve the paraffin building-up and open the conduit, thus leading to the smooth oil flow out of well.

  15. Hollow Cone Spray Characterization and Integral Modeling

    OpenAIRE

    Bollweg, Peter

    2013-01-01

    The thesis presents a computationally efficient spray model for hollow cone sprays suitable for engine system simulation of direct injecting gasoline internal combustion engines. The model describes the transient evolution of the spray as a two-phase jet. Spatial gradients are resolved along the main injection direction. Momentum exchange, droplet heat-up, and fuel evaporation are accounted for. Diffusive transport of momentum, energy, and fuel species mass between the dense spray zone an...

  16. Chalcogenide glass hollow core microstructured optical fibers

    Science.gov (United States)

    Shiryaev, Vladimir S.

    2015-03-01

    The recent developments on chalcogenide glass hollow core microstructured optical fibers (HC-MOFs) are presented. The comparative analysis of simulated optical properties for chalcogenide HC-MOFs of negative-curvature with different size and number of capillaries is given. The technique for the manufacture of microstructured chalcogenide preforms, which includes the assembly of the substrate glass tube and 8-10 capillaries, is described. Further trends to improve the optical transmission in chalcogenide NCHCFs are considered.

  17. Hollow Cathode With Multiple Radial Orifices

    Science.gov (United States)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  18. The Hollow Cathode Phase of Pseudospark Operation

    Science.gov (United States)

    1993-06-01

    THE HOLLOW CATHODE PHASE OF PSEUDOSPARK OPERATION L. Pitchford and J. P. Boeuf University Paul Sabatier, France V. Puech University De Paris-Sud...ORGANIZATION NAME(S) AND ADDRESS(ES) University Paul Sabatier, France 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME...Appl. Phys. 53, 1699 (1988). [9] A. Anders, S. Anders, and M. Gundersen, submitted to Phys. Rev. Lett. [10] J. P. Boeuf and L. Pitchford , IEEE

  19. Anodizing of High Electrically Stressed Components

    Energy Technology Data Exchange (ETDEWEB)

    Flores, P. [NSTec; Henderson, D. J. [NSTec; Good, D. E. [NSTec; Hogge, K. [NSTec; Mitton, C. V. [NSTec; Molina, I. [NSTec; Naffziger, C. [NSTec; Codova, S. R. [SNL; Ormond, E. U. [SNL

    2013-06-01

    Anodizing creates an aluminum oxide coating that penetrates into the surface as well as builds above the surface of aluminum creating a very hard ceramic-type coating with good dielectric properties. Over time and use, the electrical carrying components (or spools in this case) experience electrical breakdown, yielding undesirable x-ray dosages or failure. The spool is located in the high vacuum region of a rod pinch diode section of an x-ray producing machine. Machine operators have recorded decreases in x-ray dosages over numerous shots using the reusable spool component, and re-anodizing the interior surface of the spool does not provide the expected improvement. A machine operation subject matter expert coated the anodized surface with diffusion pump oil to eliminate electrical breakdown as a temporary fix. It is known that an anodized surface is very porous, and it is because of this porosity that the surface may trap air that becomes a catalyst for electrical breakdown. In this paper we present a solution of mitigating electrical breakdown by oiling. We will also present results of surface anodizing improvements achieved by surface finish preparation and surface sealing. We conclude that oiling the anodized surface and using anodized hot dip sealing processes will have similar results.

  20. Novel fabrication technique of hollow fibre support for micro-tubular solid oxide fuel cells

    Science.gov (United States)

    Othman, Mohd Hafiz Dzarfan; Droushiotis, Nicolas; Wu, Zhentao; Kelsall, Geoff; Li, K.

    In this work, a cerium-gadolinium oxide (CGO)/nickel (Ni)-CGO hollow fibre (HF) for micro-tubular solid oxide fuel cells (SOFCs), which consists of a fully gas-tight outer electrolyte layer supported on a porous inner composite anode layer, has been developed via a novel single-step co-extrusion/co-sintering technique, followed by an easy reduction process. After depositing a multi-layers cathode layer and applying current collectors on both anode and cathode, a micro-tubular SOFC is developed with the maximum power densities of 440-1000 W m -2 at 450-580 °C. Efforts have been made in enhancing the performance of the cell by reducing the co-sintering temperature and improving the cathode layer and current collection from inner (anode) wall. The improved cell produces maximum power densities of 3400-6800 W m -2 at 550-600 °C, almost fivefold higher than the previous cell. Further improvement has been carried out by reducing thickness of the electrolyte layer. Uniform and defect-free outer electrolyte layer as thin as 10 μm can be achieved when the extrusion rate of the outer layer is controlled. The highest power output of 11,100 W m -2 is obtained for the cell of 10 μm electrolyte layer at 600 °C. This result further highlights the potential of co-extrusion technique in producing high quality dual-layer HF support for micro-tubular SOFC.

  1. Formation of hollow atoms above a surface

    Science.gov (United States)

    Briand, Jean Pierre; Phaneuf, Ronald; Terracol, Stephane; Xie, Zuqi

    2012-06-01

    Slow highly stripped ions approaching or penetrating surfaces are known to capture electrons into outer shells of the ions, leaving the innermost shells empty, and forming hollow atoms. Electron capture occurs above and below the surfaces. The existence of hollow atoms below surfaces e.g. Ar atoms whose K and L shells are empty, with all electrons lying in the M and N shells, was demonstrated in 1990 [1]. At nm above surfaces, the excited ions may not have enough time to decay before hitting the surfaces, and the formation of hollow atoms above surfaces has even been questioned [2]. To observe it, one must increase the time above the surface by decelerating the ions. We have for the first time decelerated O^7+ ions to energies as low as 1 eV/q, below the minimum energy gained by the ions due to the acceleration by their image charge. As expected, no ion backscattering (trampoline effect) above dielectric (Ge) was observed and at the lowest ion kinetic energies, most of the observed x-rays were found to be emitted by the ions after surface contact. [4pt] [1] J. P. Briand et al., Phys.Rev.Lett. 65(1990)159.[0pt] [2] J.P. Briand, AIP Conference Proceedings 215 (1990) 513.

  2. Space Charge MitigationWith Longitudinally Hollow Bunches

    CERN Document Server

    Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  3. Interference Assembly and Fretting Wear Analysis of Hollow Shaft

    OpenAIRE

    Chuanjun Han; Jie Zhang

    2014-01-01

    Fretting damage phenomenon often appears in the interference fit assembly. The finite element model of hollow shaft and shaft sleeve was established, and the equivalent stress and contact stress were computed after interference assembly. The assembly body of hollow shaft and shaft sleeve was in whirling bending load, and the contact status (sticking, sliding, and opening) and the distribution of stress along one typical contact line were computed under different loads, interferences, hollow d...

  4. Preparation of Nanocrystalline MoS2 Hollow Spheres

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Nanocrystalline MoS2 with hollow spherical morphology has been prepared by the hydrothermal method. The products are characterized by means of X-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The experimental results give the evidence that the sample is consists of hollow spheres 400~600 nm in diameter, and there is much whisker on the surface of MoS2 hollow sphere.

  5. Generation of a Dark Hollow Beam inside a Cavity

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; LU Xuan-Hui; CHEN Xu-Min; HE Sai-Ling

    2004-01-01

    @@ A new method is introduced to generate a hollow beam inside a cavity. Using a matrix eigenvalue method, the laser resonator with optical diffraction elements is theoretically analysed and simulated. The hollow beam can be obtained theoretically by controlling the parameters of the diffraction functions. After designed the diffraction components in the cavity, a hollow beam of good quality is realized experimentally using a YAG solid state laser.

  6. Optical properties of hollow calcium aluminate glass waveguides.

    Science.gov (United States)

    Abel, T; Harrington, J A; Foy, P R

    1994-06-20

    Calcium aluminate glass has a refractive index less than 1 at 10.6 µ, and therefore it is a good candidate for a hollow fiber for the transmission of CO(2) laser energy. We have drawn hollow calcium aluminate glass fibers with inner diameters ranging from 380 to 500 µ. The loss for our 500-µm inner-diameter hollow glass fibers measured at 10.6 µm is 8.6 dB/m.

  7. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  8. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    Science.gov (United States)

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  9. Dual-Anode Nickel/Hydrogen Cell

    Science.gov (United States)

    Gahn, Randall F.; Ryan, Timothy P.

    1994-01-01

    Use of two hydrogen anodes in nickel/hydrogen cell reduces ohmic and concentration polarizations contributing to internal resistance, yielding cell with improved discharging performance compared to single-anode cell. Dual-anode concept incorporated into nickel/hydrogen cells of individual pressure-vessel type (for use aboard spacecraft) and common pressure-vessel type, for use on Earth to store electrical energy from photovoltaic sources, "uninterruptible" power supplies of computer and telephone systems, electric vehicles, and load leveling on power lines. Also applicable to silver/hydrogen and other metal/gas batteries.

  10. Anode readout for pixellated CZT detectors

    Science.gov (United States)

    Narita, Tomohiko; Grindlay, Jonathan E.; Hong, Jaesub; Niestemski, Francis C.

    2004-02-01

    Determination of the photon interaction depth offers numerous advantages for an astronomical hard X-ray telescope. The interaction depth is typically derived from two signals: anode and cathode, or collecting and non-collecting electrodes. We present some preliminary results from our depth sensing detectors using only the anode pixel signals. By examining several anode pixel signals simultaneously, we find that we can estimate the interaction depth, and get sub-pixel 2-D position resolution. We discuss our findings and the requirements for future ASIC development.

  11. Magnesium anode for chloride ion batteries.

    Science.gov (United States)

    Zhao, Xiangyu; Li, Qiang; Zhao-Karger, Zhirong; Gao, Ping; Fink, Karin; Shen, Xiaodong; Fichtner, Maximilian

    2014-07-23

    A key advantage of chloride ion battery (CIB) is its possibility to use abundant electrode materials that are different from those in Li ion batteries. Mg anode is presented as such a material for the first time and Mg/C composite prepared by ball milling of Mg and carbon black powders or thermally decomposed MgH2/C composite has been tested as anode for CIB. The electrochemical performance of FeOCl/Mg and BiOCl/Mg was investigated, demonstrating the feasibility of using Mg as anode.

  12. Complex Hollow Nanostructures: Synthesis and Energy-Related Applications.

    Science.gov (United States)

    Yu, Le; Hu, Han; Wu, Hao Bin; Lou, Xiong Wen David

    2017-04-01

    Hollow nanostructures offer promising potential for advanced energy storage and conversion applications. In the past decade, considerable research efforts have been devoted to the design and synthesis of hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, and building block and interior architecture to boost their electrochemical performance, fulfilling the increasing global demand for renewable and sustainable energy sources. In this Review, we present a comprehensive overview of the synthesis and energy-related applications of complex hollow nanostructures. After a brief classification, the design and synthesis of complex hollow nanostructures are described in detail, which include hierarchical hollow spheres, hierarchical tubular structures, hollow polyhedra, and multi-shelled hollow structures, as well as their hybrids with nanocarbon materials. Thereafter, we discuss their niche applications as electrode materials for lithium-ion batteries and hybrid supercapacitors, sulfur hosts for lithium-sulfur batteries, and electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. The potential superiorities of complex hollow nanostructures for these applications are particularly highlighted. Finally, we conclude this Review with urgent challenges and further research directions of complex hollow nanostructures for energy-related applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Manufacturing hollow obturator with resilient denture liner on post hemimaxillectomy

    Directory of Open Access Journals (Sweden)

    Michael Josef Kridanto Kamadjaja

    2006-03-01

    Full Text Available A resilient denture liner is placed in the part of the hollow obturator base that contacts to post hemimaxillectomy mucosa. Replacing the resilient denture liner can makes the hollow obturator has an intimate contact with the mucosa, so it can prevents the mouth liquid enter to the cavum nasi and sinus, also eliminates painful because of using the hollow obturator. Resilient denture liner is a soft and resilient material that applied to the fitting surface of a denture in order to allow a more distribution of load. A case was reported about using the hollow obturator with resilient denture liner on post hemimaxillectomy to overcome these problems.

  14. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes) are predo......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...

  15. Characterization of W Coating on Cu Substrate Prepared by Double-Glow Discharge%Characterization of W Coating on Cu Substrate Prepared by Double-Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    张福斌; 王正铎; 陈强; 蔡惠平

    2012-01-01

    In this study, tungsten (W) was coated on a copper (Cu) substrate by using doubleglow discharge technique using a pure W panel as the target and argon (Ar) as the discharge and sputtering gas. The crystal structure of the W coating was examined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed with cross-section images to investigate the penetration depth of W into the Cu body. Additionally, the properties of wearability resistance, corrosion resistance and mechanical strength of the W coated Cu matrix were also measured. It is concluded that in double-glow plasma, W coated Cu can be facilely prepared. It is noticed that the treatment temperature heavily dominates the properties of the W-Cu composite.

  16. Raspberry-like Nanostructured Silicon Composite Anode for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Fang, Shan; Tong, Zhenkun; Nie, Ping; Liu, Gao; Zhang, Xiaogang

    2017-06-07

    Adjusting the particle size and nanostructure or applying carbon materials as the coating layers is a promising method to hold the volume expansion of Si for its practical application in lithium-ion batteries (LIBs). Herein, the mild carbon coating combined with a molten salt reduction is precisely designed to synthesize raspberry-like hollow silicon spheres coated with carbon shells (HSi@C) as the anode materials for LIBs. The HSi@C exhibits a remarkable electrochemical performance; a high reversible specific capacity of 886.2 mAh g(-1) at a current density of 0.5 A g(-1) after 200 cycles is achieved. Moreover, even after 500 cycles at a current density of 2.0 A g(-1), a stable capacity of 516.7 mAh g(-1) still can be obtained.

  17. Masking of aluminum surface against anodizing

    Science.gov (United States)

    Crawford, G. B.; Thompson, R. E.

    1969-01-01

    Masking material and a thickening agent preserve limited unanodized areas when aluminum surfaces are anodized with chromic acid. For protection of large areas it combines well with a certain self-adhesive plastic tape.

  18. Anodic bonding of diamond to glass

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, R. [Materials and Technologies Corp., Poughkeepsie, NY (United States); Trolio, L.M. [Geo-Centers, Inc., Fort Washington, MD (United States); Butler, J.E. [Naval Research Lab., Washington, DC (United States)

    1995-12-31

    A method is described for anodically bonding smooth nanocrystalline diamond films to glass substrates to form extremely flat diamond membranes with the smoothest side available of patterning absorber structures to form masks for proximity focused x-ray lithography.

  19. Anode-Free Rechargeable Lithium Metal Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Jiangfeng [The Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland WA 99354 USA; Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Adams, Brian D. [The Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland WA 99354 USA; Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Zheng, Jianming [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Xu, Wu [The Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland WA 99354 USA; Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Henderson, Wesley A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Wang, Jun [A123 Systems Research and Development, Waltham MA 02451 USA; Bowden, Mark E. [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Xu, Suochang [Earth and Biological Science Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Hu, Jianzhi [The Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland WA 99354 USA; Earth and Biological Science Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Zhang, Ji-Guang [The Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland WA 99354 USA; Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA

    2016-08-18

    Anode-free rechargeable lithium (Li) batteries (AFLBs) are phenomenal energy storage systems due to their significantly increased energy density and reduced cost relative to Li-ion batteries, as well as ease of assembly owing to the absence of an active (reactive) anode material. However, significant challenges, including Li dendrite growth and low cycling Coulombic efficiency (CE), have prevented their practical implementation. Here, we report for the first time an anode-free rechargeable lithium battery based on a Cu||LiFePO4 cell structure with an extremely high CE (> 99.8%). This results from the utilization of both an exceptionally stable electrolyte and optimized charge/discharge protocols which minimize the corrosion of the in-situ formed Li metal anode.

  20. The Chemically Synthesized Ageladine A-Derivative LysoGlow84 Stains Lysosomes in Viable Mammalian Brain Cells and Specific Structures in the Marine Flatworm Macrostomum lignano

    Directory of Open Access Journals (Sweden)

    Thorsten Mordhorst

    2015-02-01

    Full Text Available Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84. The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms’ anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms.

  1. The chemically synthesized ageladine A-derivative LysoGlow84 stains lysosomes in viable mammalian brain cells and specific structures in the marine flatworm Macrostomum lignano.

    Science.gov (United States)

    Mordhorst, Thorsten; Awal, Sushil; Jordan, Sebastian; Petters, Charlotte; Sartoris, Linda; Dringen, Ralf; Bickmeyer, Ulf

    2015-02-11

    Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms' anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms.

  2. Lithium Ion Battery Anode Aging Mechanisms

    Directory of Open Access Journals (Sweden)

    Victor Agubra

    2013-03-01

    Full Text Available Degradation mechanisms such as lithium plating, growth of the passivated surface film layer on the electrodes and loss of both recyclable lithium ions and electrode material adversely affect the longevity of the lithium ion battery. The anode electrode is very vulnerable to these degradation mechanisms. In this paper, the most common aging mechanisms occurring at the anode during the operation of the lithium battery, as well as some approaches for minimizing the degradation are reviewed.

  3. Lithium Ion Battery Anode Aging Mechanisms

    OpenAIRE

    Victor Agubra; Jeffrey Fergus

    2013-01-01

    Degradation mechanisms such as lithium plating, growth of the passivated surface film layer on the electrodes and loss of both recyclable lithium ions and electrode material adversely affect the longevity of the lithium ion battery. The anode electrode is very vulnerable to these degradation mechanisms. In this paper, the most common aging mechanisms occurring at the anode during the operation of the lithium battery, as well as some approaches for minimizing the degradation are reviewed.

  4. Ultraviolet photoluminescence of porous anodic alumina films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.

  5. Anodic growth of titanium dioxide nanostructures

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

  6. Synthesis and TL glow curve analysis of BaSO{sub 4}:Eu,Dy phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Rangeela Devi, Y. [Department of Physics, Manipur University, Canchipur, Imphal 795003 (India); Pachhunga University College, Aizawl, Mizoram (India); Dorendrajit Singh, S., E-mail: dorendrajit@yahoo.co.in [Department of Physics, Manipur University, Canchipur, Imphal 795003 (India)

    2012-06-15

    The polycrystalline samples of Ba{sub 1-x-y}SO{sub 4}:Eu{sub x},Dy{sub y} (0{<=}x{<=}1, 0{<=}y{<=}1) have been prepared using the chemical co-precipitation technique. The thermoluminescence (TL) sensitivity of the samples have been found changing with the value of x and y and the highest TL intensity is for Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02}. The sample has been characterised by x-ray diffraction (XRD). The samples are found to have orthorhombic structure. For TL analysis Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02} is annealed at different temperatures ranging from 873 to 1173 K. Kinetic parameters of all the TL glow curves of Ba{sub 1-x-y}SO{sub 4}:Eu{sub x},Dy{sub y} for different values of x and y and also for the TL glow curves Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02} annealed at different temperatures have been found out using computerised glow curve deconvolution (CGCD) method. The activation energy for the most intense TL peak at (444-453 K) is found out to be 1.26 eV and order of kinetics is 1.35. - Highlights: Black-Right-Pointing-Pointer TL study of BaSO{sub 4}:Eu,Dy is reported for the first time. Black-Right-Pointing-Pointer The kinetic parameters are evaluated by CGCD. Black-Right-Pointing-Pointer Effect of concentration, annealing temperature and dose response curve discussed.

  7. Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

    2011-11-15

    A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

  8. Fibrous zinc anodes for high power batteries

    Science.gov (United States)

    Zhang, X. Gregory

    This paper introduces newly developed solid zinc anodes using fibrous material for high power applications in alkaline and large size zinc-air battery systems. The improved performance of the anodes in these two battery systems is demonstrated. The possibilities for control of electrode porosity and for anode/battery design using fibrous materials are discussed in light of experimental data. Because of its mechanical integrity and connectivity, the fibrous solid anode has good electrical conductivity, mechanical stability, and design flexibility for controlling mass distribution, porosity and effective surface area. Experimental data indicated that alkaline cells made of such anodes can have a larger capacity at high discharging currents than commercially available cells. It showed even greater improvement over commercial cells with a non-conventional cell design. Large capacity anodes for a zinc-air battery have also been made and have shown excellent material utilization at various discharge rates. The zinc-air battery was used to power an electric bicycle and demonstrated good results.

  9. General design of hollow porous CoFe2O4 nanocubes from metal-organic frameworks with extraordinary lithium storage

    Science.gov (United States)

    Guo, Hong; Li, Tingting; Chen, Weiwei; Liu, Lixiang; Yang, Xiangjun; Wang, Yapeng; Guo, Yicheng

    2014-11-01

    Hollow porous CoFe2O4 nanocubes from metal-organic frameworks were fabricated through a general facile strategy. The intrinsic hollow nanostructure can shorten the lengths for both electronic and ionic transport, enlarge the surface area of electrodes, and improve accommodation of the volume change during Li insertion/extraction cycling. The hybrid multi-elements characteristics allow the volume change to take place in a stepwise manner during the electrochemical cycle. Therefore, the as-prepared CoFe2O4 electrode exhibits outstanding performance as anode materials for lithium ion batteries. The stable capacity arrives at 815 mA h g-1 for 20 C. Subsequently, a specific capacity of ca. 1043 mA h g-1 is recovered when the current rate reduces back to 1 C after 200 cycles. This general strategy may shed light on a new avenue for large-scale synthesis of hollow porous hybrid nanocubes via MOFs for energy storage, environmental remediation and other novel applications.Hollow porous CoFe2O4 nanocubes from metal-organic frameworks were fabricated through a general facile strategy. The intrinsic hollow nanostructure can shorten the lengths for both electronic and ionic transport, enlarge the surface area of electrodes, and improve accommodation of the volume change during Li insertion/extraction cycling. The hybrid multi-elements characteristics allow the volume change to take place in a stepwise manner during the electrochemical cycle. Therefore, the as-prepared CoFe2O4 electrode exhibits outstanding performance as anode materials for lithium ion batteries. The stable capacity arrives at 815 mA h g-1 for 20 C. Subsequently, a specific capacity of ca. 1043 mA h g-1 is recovered when the current rate reduces back to 1 C after 200 cycles. This general strategy may shed light on a new avenue for large-scale synthesis of hollow porous hybrid nanocubes via MOFs for energy storage, environmental remediation and other novel applications. Electronic supplementary information (ESI

  10. Surface modification of austenitic steel by various glow-discharge nitriding methods

    Directory of Open Access Journals (Sweden)

    Tomasz Borowski

    2015-09-01

    Full Text Available Recent years have seen intensive research on modifying glow-discharge nitriding processes. One of the most commonly used glow-discharge methods includes cathodic potential nitriding (conventional method, and active screen plasma nitriding. Each of these methods has a number of advantages. One very important, common feature of these techniques is full control of the microstructure, chemical and phase composition, thickness and the surface topography of the layers formed. Another advantage includes the possibility of nitriding such materials as: austenitic steels or nickel alloys, i.e. metallic materials which do not diffuse nitrogen as effectively as ferritic or martensitic steels. However, these methods have some disadvantages as well. In the case of conventional plasma nitriding, engineers have to deal with the edge effect, which makes it difficult to use this method for complexly shaped components. In turn, in the case of active screen plasma nitriding, the problem disappears. A uniform, smooth layer forms, but is thinner, softer and is not as resistant to friction compared to layers formed using the conventional method. Research is also underway to combine these methods, i.e. use an active screen in conventional plasma nitriding at cathodic potential. However, there is a lack of comprehensive data presenting a comparison between these three nitriding processes and the impact of pulsating current on the formation of the microstructure and functional properties of austenitic steel surfaces. The article presents a characterisation of nitrided layers produced on austenitic X2CrNiMo17-12-2 (AISI 316L stainless steel in the course of glow-discharge nitriding at cathodic potential, at plasma potential and at cathodic potential incorporating an active screen. All processes were carried out at 440 °C under DC glow-discharge conditions and in 100 kHz frequency pulsating current. The layers were examined in terms of their microstructure, phase and

  11. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    Science.gov (United States)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  12. Analysis of green fluorescent protein bioluminescence in vivo and in vitro using a glow discharge

    Science.gov (United States)

    Hernández, L.; Mandujano, L. A.; Cuevas, J.; Reyes, P. G.; Osorio-González, D.

    2015-03-01

    The discovery of fluorescent proteins has been a revolution in cell biology and related sciences because of their many applications, mainly emphasizing their use as cellular markers. The green fluorescent protein (GFP) is one of the most used as it requires no cofactors to generate fluorescence and retains this property into any organism when it is expressed by recombinant DNA techniques, which is a great advantage. In this work, we analyze the emission spectra of recombinant green fluorescent protein in vivo and in vitro exposed to a glow discharge plasma of nitrogen in order to relate electron temperature to fluorescence intensity.

  13. Surface modification of austenitic steel by various glow-discharge nitriding methods

    Directory of Open Access Journals (Sweden)

    Tomasz Borowski

    2015-09-01

    Full Text Available Recent years have seen intensive research on modifying glow-discharge nitriding processes. One of the most commonly used glow-discharge methods includes cathodic potential nitriding (conventional method, and active screen plasma nitriding. Each of these methods has a number of advantages. One very important, common feature of these techniques is full control of the microstructure, chemical and phase composition, thickness and the surface topography of the layers formed. Another advantage includes the possibility of nitriding such materials as: austenitic steels or nickel alloys, i.e. metallic materials which do not diffuse nitrogen as effectively as ferritic or martensitic steels. However, these methods have some disadvantages as well. In the case of conventional plasma nitriding, engineers have to deal with the edge effect, which makes it difficult to use this method for complexly shaped components. In turn, in the case of active screen plasma nitriding, the problem disappears. A uniform, smooth layer forms, but is thinner, softer and is not as resistant to friction compared to layers formed using the conventional method. Research is also underway to combine these methods, i.e. use an active screen in conventional plasma nitriding at cathodic potential. However, there is a lack of comprehensive data presenting a comparison between these three nitriding processes and the impact of pulsating current on the formation of the microstructure and functional properties of austenitic steel surfaces. The article presents a characterisation of nitrided layers produced on austenitic X2CrNiMo17-12-2 (AISI 316L stainless steel in the course of glow-discharge nitriding at cathodic potential, at plasma potential and at cathodic potential incorporating an active screen. All processes were carried out at 440 °C under DC glow-discharge conditions and in 100 kHz frequency pulsating current. The layers were examined in terms of their microstructure, phase and

  14. Reduction of TiO2 with hydrogen cold plasma in DC pulsed glow discharge

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-wen; DING Wei-zhong; LU Xiong-gang; GUO Shu-qiang; XU Kuang-di

    2005-01-01

    The reduction of TiO2 to Ti2O3 with hydrogen cold plasma generated by a DC pulsed glow discharge was realized under 2 500 Pa at 1 233 K. Only a little of Ti10O19 and Ti9O17 was detected for using molecular hydrogen.Enhancement effects of hydrogen cold plasma on the reduction were discussed in terms of thermodynamic coupling,kinetics and plasma sheath. The exited hydrogen species are considered more effective reducing agents. It is instructive to reduce refractory oxides with plasma hydrogen at the reduced temperature.

  15. Formation and dynamics of nano-particles in a stratified spherical glow discharge

    Science.gov (United States)

    Sakhapov, S. Z.; Fedoseev, A. V.; Sukhinin, G. I.; Novopashin, S. A.

    2015-04-01

    The formation of clouds of dust nano-particles in a spherical dc glow discharge in ethanol was observed. Nano-particles were formed in a process of coagulation of ethanol dissociation products in a plasma of gas discharge. During the process the particles were captured into clouds in the electric potential wells of the strong striations of a spherical discharge. Periodically, the cloud of nano-particles experienced some sudden instability (explosion), and started to move to the cathode at high velocity. It was proved that the velocity of the particle clouds was an exponentially decaying function of time as in the case of dissipative dust solitary waves.

  16. Relativistic feedback models of terrestrial gamma-ray flashes and gamma-ray glows

    Science.gov (United States)

    Dwyer, J. R.

    2015-12-01

    Relativistic feedback discharges, also known as dark lightning, are capable of explaining many of the observed properties of terrestrial gamma-ray flashes (TGFs) and gamma-ray glows, both created within thunderstorms. During relativistic feedback discharges, the generation of energetic electrons is self-sustained via the production of backward propagating positrons and back-scattered x-rays, resulting in very larges fluxes of energetic radiation. In addition, ionization produces large electric currents that generate LF/VLF radio emissions and eventually discharge the electric field, terminating the gamma-ray production. In this presentation, new relativistic feedback model results will be presented and compared to recent observations.

  17. Radial Evolution of the Atmospheric Pressure Glow Discharge in Helium Controlled by Dielectric Barrier

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan-Tao; WANG De-Zhen; WANG Yan-Hui; LIU Cheng-Sen

    2005-01-01

    @@ The radial evolution of atmospheric pressure glow discharge in helium is presented by numerical simulation. The calculations reveal the mechanism of two current peaks per half cycle. The first breakdown occurs firstly in the central region of the electrode, and then spreads to the edge, while the second breakdown ignites at the periphery firstly, and then propagates toward the discharge central region. The simulations indicate that radial electric fields and radial sheath play an important role in the evolution of the second peak. These results agree fundamentally with the experimental observations.

  18. Study of stability of dc glow discharges with the use of Comsol Multiphysics software

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, P G C; Benilov, M S; Faria, M J [Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

    2011-10-19

    Stability of different axially symmetric modes of current transfer in dc glow discharges is investigated in the framework of the linear stability theory with the use of Comsol Multiphysics software. Conditions of current-controlled microdischarges in xenon are treated as an example. Both real and complex eigenvalues have been detected, meaning that perturbations can vary with time both monotonically and with oscillations. In general, results given by the linear stability theory confirm intuitive concepts developed in the literature and conform to the experiment. On the other hand, suggestions are provided for further experimental and theoretical work.

  19. Stabilization of a cold cathode electron beam glow discharge for surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Mingolo, N.; Gonzalez, C.R. [Lab. de Haces Dirigidos, Depto. de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Martinez, O.E. [Lab. de Electronica Cuantica, Depto. de Fisica, Universidad de Buenos Aires, Pabellon 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Rocca, J.J. [Department of Electrical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

    1997-10-01

    We have demonstrated that the reproducibility of electron beam pulses generated by a high power, cold cathode glow discharge is greatly improved by adding a small continuous keep-alive discharge current. A current of the order of 200 {mu}A was found to limit the shot to shot current variation to within 1.5{percent}. This stabilization in turn reduces by an order of magnitude the fluctuations of the energy density deposited on the target, demonstrating a reliable energy source for surface treatment. {copyright} {ital 1997 American Institute of Physics.}

  20. Degradation of Chloroanilines in Aqueous Solution by Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    高锦章; 胡中爱; 陆泉芳; 纳鹏君; 陈平; 刘永军; 俞洁

    2003-01-01

    Contact glow discharge electrolysis of some chloroanilines in sodium sulfate was investigated in different initial concentrations. Each of them underwent the dechlorination, deamination through oxidative degradation, and were eventually decomposed into hydrogen carbonate and carbon dioxide. It was testified that the chlorine atom and amidogen could be transformed into chloride ion and nitrite ion, respectively. Fe2+ has a remarkable catalytic effect on the degradation of them. On the basis of the detailed analysis of the intermediate products and kinetic behaviors, the reaction pathway was proposed, in which the attack of hydroxyl radical on the benzene ring of starting material might be a key step.

  1. Irregular-regular-irregular mixed mode oscillations in a glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sabuj, E-mail: sabuj.ghosh@saha.ac.in; Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Saha, Debajyoti, E-mail: debajyoti.saha@saha.ac.in; Janaki, M. S., E-mail: ms.janaki@saha.ac.in; Iyengar, A. N. Sekar, E-mail: ansekar.iyengar@saha.ac.in [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)

    2015-05-15

    Floating potential fluctuations of a glow discharge plasma are found to exhibit different kinds of mixed mode oscillations. Power spectrum analysis reveals that with change in the nature of the mixed mode oscillation (MMO), there occurs a transfer of power between the different harmonics and subharmonics. The variation in the chaoticity of different types of mmo was observed with the study of Lyapunov exponents. Estimates of correlation dimension and the Hurst exponent suggest that these MMOs are of low dimensional nature with an anti persistent character. Numerical modeling also reflects the experimentally found transitions between the different MMOs.

  2. Nanostructures Using Anodic Aluminum Oxide

    Science.gov (United States)

    Valmianski, Ilya; Monton, Carlos M.; Pereiro, Juan; Basaran, Ali C.; Schuller, Ivan K.

    2013-03-01

    We present two fabrication methods for asymmetric mesoscopic dot arrays over macroscopic areas using anodic aluminum oxide templates. In the first approach, metal is deposited at 45o to the template axis to partially close the pores and produce an elliptical shadow-mask. In the second approach, now underway, nanoimprint lithography on a polymer intermediary layer is followed by reactive ion etching to generate asymmetric pore seeds. Both these techniques are quantified by an analysis of the lateral morphology and lattice of the pores or dots using scanning electron microscopy and a newly developed MATLAB based code (available for free download at http://ischuller.ucsd.edu). The code automatically provides a segmentation of the measured area and the statistics of morphological properties such as area, diameter, and eccentricity, as well as the lattice properties such as number of nearest neighbors, and unbiased angular and radial two point correlation functions. Furthermore, novel user defined statistics can be easily obtained. We will additionally present several applications of these methods to superconducting, ferromagnetic, and organic nanostructures. This work is supported by AFOSR FA9550-10-1-0409

  3. Numerical Modeling of the Atmospheric-Pressure Helium Plasma Formed During Spark-to-Glow Discharge Transition

    Science.gov (United States)

    Demkin, V. P.; Melnichuk, S. V.

    2017-06-01

    Results of numerical experiment on modeling of the atmospheric-pressure plasma formed during the spark-to-glow discharge transition in helium in low-current non-stationary plasmatron are presented. The numerical experiment is performed using the developed 2D physical and mathematical plasma model in the drift-diffusion approximation. Results of numerical calculation of the dynamics of discharge evolution are confirmed by the experimental data on the atmospheric-pressure plasma dynamics formed in the plasmatron during the spark-to-glow discharge transition. It is demonstrated that with preset initial conditions characteristic for spark breakdown, further discharge evolution leads to the formation of the near-cathode zone of the potential drop and the pulsed behavior of the electric current of the discharge. After the current pulse, the discharge transforms into the quasi-stationary mode with parameters characteristic for the glow discharge with monotonically increasing electric current and transverse dimensions of the plasma column.

  4. One-pot chemical route for morphology-controllable fabrication of Sn-Sb micro/nano-structures: Advanced anode materials for lithium and sodium storage

    Science.gov (United States)

    Yi, Zheng; Han, Qigang; Geng, Di; Wu, Yaoming; Cheng, Yong; Wang, Limin

    2017-02-01

    A series of morphology/component-controllable Sn-Sb micro/nano-structures are fabricated by a one-pot replacement reaction technique employing metallic Sn as both template and reducing agent. Typically, nanoscaled Sn as template and ethyl alcohol as solvent give the hollow structure, while micron-sized Sn as precursor and ethylene glycol as solvent produce the dendritic product. Other mixed structures are also obtained by this one-pot route. As anode materials for lithium-ion batteries, the hollow or dendritic Sn-Sb materials exhibit higher discharge capacities compared with the corresponding Sb samples as well as the Sn templates. Especially, for the Sn-Sb hollow spheres, a high discharge capacity of 820.7 mAh g-1 after first cycle and a reversible capacity of 751 mAh g-1 are achieved after 100 cycles at a current density of 100 mA g-1. Meanwhile, the hollow Sn-Sb structure delivers a specific capacity of 451.3 mA h g-1 at 500 mA g-1 after 150 cycles when used for sodium ion batteries. The superior electrochemical performance that are higher than many reported results can be attributed to the special morphology and structure, which can shorten the transportation distance of lithium/sodium ion and provide extra free space to buffer the volume expansion during the lithium/sodium insertion/extraction.

  5. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  6. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  7. Preparation of spherical hollow alumina particles by thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonkyung [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Choi, Sooseok [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151‐742 (Korea, Republic of); Oh, Seung-Min [Daejoo Electronic Materials Co., 1236‐10 Jeongwang-dong, Siheung-si, Kyunggi-do 429‐848 (Korea, Republic of); Park, Dong-Wha, E-mail: dwpark@inha.ac.kr [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of)

    2013-02-01

    Spherical hollow particles were prepared from solid alumina powders using DC arc thermal plasma, and then spray coating was performed with the as-prepared particles. Operating variables for the hollow particle preparation process were additional plasma gas, input power, and carrier gas flow rate. The spherical hollow alumina particles were produced in the case of using additive gas of H{sub 2} or N{sub 2}, while alumina surface was hardly molten in the pure argon thermal plasma. In addition, the hollow particles were well produced in high power and low carrier gas conditions due to high melting point of alumina. Hollow structure was confirmed by focused ion beam-scanning electron microscopy analysis. Morphology and size distribution of the prepared particles that were examined by field emission-scanning electron microscopy and phase composition of the particles was characterized by X-ray diffraction. In the spray coating process, the as-prepared hollow particles showed higher deposition rate. - Highlights: ► Spherical hollow alumina powder was prepared by non-transferred DC arc plasma. ► Diatomic gasses were added in Ar plasma for high power. ► Prepared hollow alumina powder was efficient for the plasma spray coating.

  8. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material.

    Science.gov (United States)

    Shrestha, Bidhan; Hughes, E Richard; Kumar Singh, Raj; Suwal, Pramita; Parajuli, Prakash Kumar; Shrestha, Pragya; Sharma, Arati; Adhikari, Galav

    2015-01-01

    Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  9. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    OpenAIRE

    Weon-Sik Chae; Hee-Ok Lee; Seung-Lim Oh

    2011-01-01

    Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  10. Wet spinning of asymmetric hollow fibre membranes for gas separation

    NARCIS (Netherlands)

    Hof, van 't Jacob Adriaan

    1988-01-01

    This thesis describes the spinning and characterizatin of hollow fibre membranes for gas separation. The type of fibres studied here are made by a wet spinning process. A homogeneous solution is prepared, consisting of a polymer in a suitable organic solvent, and extruded as a hollow fibre. Both the

  11. Wet spinning of asymmetric hollow fibre membranes for gas separation

    NARCIS (Netherlands)

    van 't Hof, Jacob Adriaan

    1988-01-01

    This thesis describes the spinning and characterizatin of hollow fibre membranes for gas separation. The type of fibres studied here are made by a wet spinning process. A homogeneous solution is prepared, consisting of a polymer in a suitable organic solvent, and extruded as a hollow fibre. Both the

  12. Simple Spinning of Heterogeneous Hollow Microfibers on Chip.

    Science.gov (United States)

    Yu, Yue; Wei, Wenbo; Wang, Yaqing; Xu, Cong; Guo, Yaqiong; Qin, Jianhua

    2016-08-01

    A novel and simple chip-based microfluidic strategy is proposed for continuously controlled spinning of desirable hollow microfibers. These fabricated fiber-shaped materials exhibit extraordinary morphological and structural complexity, as well as a heterogeneous composition. The resulting specific hollow microfibers have potential applications in numerous chemical and biomedical fields.

  13. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    Directory of Open Access Journals (Sweden)

    Weon-Sik Chae

    2011-12-01

    Full Text Available Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  14. Biodegradable hollow fibres for the controlled release of hormones

    NARCIS (Netherlands)

    Eenink, M.J.D.; Feijen, Jan; Olijslager, J.; Albers, J.H.M.; Rieke, J.C.; Greidanus, P.J.

    1987-01-01

    Poly(l-lactide), (PLLA), hollow fibres were prepared using a dry-wet phase inversion spinning process. The effect of several spinning parameters (i.e. bore medium flow rate, spinning dope extrusion rate, fibre take-up rate, and spinning height) on the hollow fibre dimensions is reported. The use of

  15. Biodegradable hollow fibres for the controlled release of hormones

    NARCIS (Netherlands)

    Eenink, M.J.D.; Feijen, J.; Olijslager, J.; Albers, J.H.M.; Rieke, J.C.; Greidanus, P.J.

    1987-01-01

    Poly(l-lactide), (PLLA), hollow fibres were prepared using a dry-wet phase inversion spinning process. The effect of several spinning parameters (i.e. bore medium flow rate, spinning dope extrusion rate, fibre take-up rate, and spinning height) on the hollow fibre dimensions is reported. The use of

  16. On the physical processes ruling an atmospheric pressure air glow discharge operating in an intermediate current regime

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L., E-mail: prevosto@waycom.com.ar; Mancinelli, B.; Chamorro, J. C.; Cejas, E. [Grupo de Descargas Eléctricas, Departamento Ing. Electromecánica, Facultad Regional Venado Tuerto (UTN), Laprida 651, Venado Tuerto (2600), Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Eléctricas, Departamento Ing. Electromecánica, Facultad Regional Venado Tuerto (UTN), Laprida 651, Venado Tuerto (2600), Santa Fe (Argentina); Instituto de Física del Plasma (CONICET), Facultad de Ciencias Exactas y Naturales (UBA) Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina)

    2015-02-15

    Low-frequency (100 Hz), intermediate-current (50 to 200 mA) glow discharges were experimentally investigated in atmospheric pressure air between blunt copper electrodes. Voltage–current characteristics and images of the discharge for different inter-electrode distances are reported. A cathode-fall voltage close to 360 V and a current density at the cathode surface of about 11 A/cm{sup 2}, both independent of the discharge current, were found. The visible emissive structure of the discharge resembles to that of a typical low-pressure glow, thus suggesting a glow-like electric field distribution in the discharge. A kinetic model for the discharge ionization processes is also presented with the aim of identifying the main physical processes ruling the discharge behavior. The numerical results indicate the presence of a non-equilibrium plasma with rather high gas temperature (above 4000 K) leading to the production of components such as NO, O, and N which are usually absent in low-current glows. Hence, the ionization by electron-impact is replaced by associative ionization, which is independent of the reduced electric field. This leads to a negative current-voltage characteristic curve, in spite of the glow-like features of the discharge. On the other hand, several estimations show that the discharge seems to be stabilized by heat conduction; being thermally stable due to its reduced size. All the quoted results indicate that although this discharge regime might be considered to be close to an arc, it is still a glow discharge as demonstrated by its overall properties, supported also by the presence of thermal non-equilibrium.

  17. AGING EFFECTS OF REPEATEDLY GLOW-DISCHARGED POLYETHYLENE - INFLUENCE ON CONTACT-ANGLE, INFRARED-ABSORPTION, ELEMENTAL SURFACE-COMPOSITION, AND SURFACE-TOPOGRAPHY

    NARCIS (Netherlands)

    VANDERMEI, HC; STOKROOS, [No Value; SCHAKENRAAD, JM; BUSSCHER, HJ

    1991-01-01

    Aging effects of repeatedly oxygen glow-discharged polyethylene surfaces were determined by water contact angle measurements, infrared (IR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, and surface topography determination. Glow-discharged surfaces were stored at room temperature and in liqu

  18. NATURAL FREQUENCIES OF SUBMERGED PIEZOCERAMIC HOLLOW SPHERES

    Institute of Scientific and Technical Information of China (English)

    Cai Jinbiao; Chen Weiqiu; Ye Guiru; Ding Haojiang

    2000-01-01

    An exact 3D analysis of free vibration of a piezoceramic hollow sphere submerged in a compressible fluid is presented in this paper.A separation method is adopted to simplify the basic equations for spherically isotropic piezoelasticity.It is shown that there are two independent classes of vibration.The first one is independent of the fluid medium as well as the electric field,while the second is associated with both the fluid parameter and the piezoelectric effect.Exact frequency equations are derived and numerical results are obtained.

  19. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a micron-scale calorimeter and a calorimetry method utilizing the micron-scale calorimeter. In accordance with the invention, there is provided a micron-scale calorimeter comprising a micro-channel string, being restrained at at least two longitudinally distanced...... positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...

  20. Nonlinear sequential laminates reproducing hollow sphere assemblages

    Science.gov (United States)

    Idiart, Martín I.

    2007-07-01

    A special class of nonlinear porous materials with isotropic 'sequentially laminated' microstructures is found to reproduce exactly the hydrostatic behavior of 'hollow sphere assemblages'. It is then argued that this result supports the conjecture that Gurson's approximate criterion for plastic porous materials, and its viscoplastic extension of Leblond et al. (1994), may actually yield rigorous upper bounds for the hydrostatic flow stress of porous materials containing an isotropic, but otherwise arbitrary, distribution of porosity. To cite this article: M.I. Idiart, C. R. Mecanique 335 (2007).

  1. Anti-resonant hexagram hollow core fibers.

    Science.gov (United States)

    Hayes, John R; Poletti, Francesco; Abokhamis, Mousavi S; Wheeler, Natalie V; Baddela, Naveen K; Richardson, David J

    2015-01-26

    Various simple anti-resonant, single cladding layer, hollow core fiber structures are examined. We show that the spacing between core and jacket glass and the shape of the support struts can be used to optimize confinement loss. We demonstrate the detrimental effect on confinement loss of thick nodes at the strut intersections and present a fabricated hexagram fiber that mitigates this effect in both straight and bent condition by presenting thin and radially elongated nodes. This fiber has loss comparable to published results for a first generation, multi-cladding ring, Kagome fiber with negative core curvature and has tolerable bend loss for many practical applications.

  2. Hollow-Cathode Source Generates Plasma

    Science.gov (United States)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  3. Hollow ballistic pendulum for plasma momentum measurements

    Science.gov (United States)

    Goncharov, S. F.; Pashinin, P. P.; Perov, V. Y.; Serov, R. V.; Yanovsky, V. P.

    1988-05-01

    A novel pendulum design—hollow ballistic pendulum—is suggested for plasma momentum measurements. It has an advantage over the pendula used earlier in laser plasma experiments of being insensitive to a momentum of matter evaporated and scattered by the pendulum wall exposed to the plasma, which usually exceeds plasma momentum to be measured. Simple expressions describing pendulum performance are derived, and requirements of shape and size are established. Using this kind of pendulum in experiments on laser acceleration of thin foils made it possible to measure the momentum of accelerated foil with an accuracy of about 10%.

  4. PREPARATION OF HOLLOW LATEX PARTICLES BY ALKALI-ACID TREATMENT

    Institute of Scientific and Technical Information of China (English)

    郝冬梅; 王新灵; 朱卫华; 唐小真; 刘成岑; 施凯

    2001-01-01

    Hollow polymer latex particles were prepared by seeded emulsion polymerization. A seed latex consisting of styrene (St), butyl acrylate(BA) copolymer was first prepared, and seeded terpolymerization of St-BA-MA(methacrylic acid) were then carried out in the absence of surfactant. Final latex was treated by a two-step treatment under alkaline and acidic conditions, thus, the particles with hollow structure were obtained. We discussed the effects of pH value, temperature and time in alkali and acid treatment processes on hollow structure within the polymer latex particles and amount of carboxylic group on particle surface. The results show that the hollow polymer latex particles with the largest hollow size can be obtained under a certain condition (pH12.5, 90°C, 3 h in alkali treatment stage and pH2.5, 85°C, 3 h in acid treatment stage).

  5. Anomalous Hollow Electron Beams in a Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.K.

    2005-04-12

    This paper reports the first observations of an anomalous hollow electron beam in the Duke storage ring. Created by exciting the single bunch beam in a lattice with a negative chromaticity, the hollow beam consists of a solid core inside and a large ring outside. We report the detailed measurements of the hollow beam phenomenon, including its distinct image pattern, spectrum signature, and its evolution with time. By capturing the post-instability bursting beam, the hollow beam is a unique model system for studying the transverse instabilities, in particular, the interplay of the wake field and the lattice nonlinearity. In addition, the hollow beam can be used as a powerful tool to study the linear and nonlinear particle dynamics in the storage ring.

  6. Size-dependent deformation mechanisms in hollow silicon nanoparticles

    Directory of Open Access Journals (Sweden)

    L. Yang

    2015-07-01

    Full Text Available Even inherently brittle hollow silicon nanoparticles (NPs can withstand larger strain to failure than solid NPs. However, the influence of wall thickness on the mechanical behavior of hollow Si NPs is not fully understood. Using molecular dynamics simulations, we investigate the compressive behavior of hollow Si NPs. Three distinct failure mechanisms of hollow NPs are uncovered, and their strength and deformability are analyzed quantitatively. For extra-thick-walled NPs, dislocations will nucleate below the contact area and cut through the particles till failure. For mid-thick-walled NPs, however, dislocations will emit from the inner surface and slip towards the outer surface. For thin-walled NPs, elastic buckling is the cause of failure. Compared to solid NPs, hollow NPs with wall thickness being around half of its outer radius can achieve significant improvement in both strength and deformability.

  7. Hollow fiber bioreactor technology for tissue engineering applications.

    Science.gov (United States)

    Eghbali, Hadis; Nava, Michele M; Mohebbi-Kalhori, Davod; Raimondi, Manuela T

    2016-01-01

    Hollow fiber bioreactors are the focus of scientific research aiming to mimic physiological vascular networks and engineer organs and tissues in vitro. The reason for this lies in the interesting features of this bioreactor type, including excellent mass transport properties. Indeed, hollow fiber bioreactors allow limitations to be overcome in nutrient transport by diffusion, which is often an obstacle to engineer sizable constructs in vitro. This work reviews the existing literature relevant to hollow fiber bioreactors in organ and tissue engineering applications. To this purpose, we first classify the hollow fiber bioreactors into 2 categories: cylindrical and rectangular. For each category, we summarize their main applications both at the tissue and at the organ level, focusing on experimental models and computational studies as predictive tools for designing innovative, dynamic culture systems. Finally, we discuss future perspectives on hollow fiber bioreactors as in vitro models for tissue and organ engineering applications.

  8. Self-templated chemically stable hollow spherical covalent organic framework

    Science.gov (United States)

    Kandambeth, Sharath; Venkatesh, V.; Shinde, Digambar B.; Kumari, Sushma; Halder, Arjun; Verma, Sandeep; Banerjee, Rahul

    2015-04-01

    Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area ~1,500 m2 g-1), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 μmol g-1 of trypsin.

  9. An Atomic Lens Using a Focusing Hollow Beam

    Institute of Scientific and Technical Information of China (English)

    夏勇; 印建平; 王育竹

    2003-01-01

    We propose a new method to generate a focused hollow laser beam by using an azimuthally distributed 2π-phase plate and a convergent thin lens, and calculate the intensity distribution of the focused hollow beam in free propagation space. The relationship between the waist w0 of the incident collimated Gaussian beam and the dark spot size of the focused hollow beam at the focal point, and the relationship between the focal length f of the thin lens and the dark spot size are studied respectively. The optical potential of the blue-detuned focused hollow beam for 85Rb atoms is calculated. Our study shows that when the larger waist w of the incident Gaussian beam and the shorter focal length f of the lens are chosen, we can obtain an extremely small dark spot size of the focused hollow beam, which can be used to form an atomic lens with a resolution of several angstroms.

  10. Anode Supported Solid Oxide Fuel Cells - Deconvolution of Degradation into Cathode and Anode Contributions

    DEFF Research Database (Denmark)

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

    2007-01-01

    The degradation of anode supported cells was studied over 1500 h as function of cell polarization either in air or oxygen on the cathode. Based on impedance analysis, contributions of anode and cathode to the increase of total resistance were assigned. Accordingly, the degradation rates of the ca...

  11. Anodized aluminum on LDEF: A current status of measurements on chromic acid anodized aluminum

    Science.gov (United States)

    Golden, Johnny L.

    1992-01-01

    Chromic acid anodize was used as the exterior coating for aluminum surfaces on LDEF to provide passive thermal control. Chromic acid anodized aluminum was also used as test specimens in thermal control coatings experiments. The following is a compilation and analysis of the data obtained thus far.

  12. Electronic Transition Spectra of Thiophenoxy and Phenoxy Radicals in Hollow Cathode Discharges

    Science.gov (United States)

    Araki, Mitsunori; Wako, Hiromichi; Niwayama, Kei; Tsukiyama, Koichi

    2014-06-01

    Diffuse interstellar bands (DIBs) still remain the longest standing unsolved problem in spectroscopy and astrochemistry, although several hundreds of DIBs have been already detected. It is expected that identifications of DIBs can give us crucial information for extraterrestrial organic molecule. One of the best approaches to identify carrier molecules of DIBs is a measurement of DIB candidate molecule produced in the laboratory to compare their absorption spectra with astronomically observed DIB spectra. Radical in a gas phase is a potential DIB candidate molecule. The electronic transitions of polyaromatic hydrocarbon radicals result in optical absorption. However, because radicals are unstable, their electronic transitions are difficult to observe using a laboratory spectrometer system. To solve this difficulty, we have developed a glow-discharge cell using a hollow cathode in which radicals can be effectively produced as a high-density plasma. The radicals produced were measured by using the cavity ringdown (CRD) spectrometer and the discharge emission spectrometer. The CRD spectrometer, which consists of a tunable pulse laser system, an optical cavity and a discharge device, is an apparatus to observe an high-resolution optical absorption spectrum. The electronic transition of the thiophenoxy radical C6H5OS was observed in the discharge emission of thiophenol C6H5OH. The electronic transition frequency of the thiophenoxy radical was measured. A optical discharge emission was examined by using a HORIBA Jobin Yvon iHR320 monochromator. We detected the phenoxy radical C6H5O in the discharge of phenol C6H5OH. The band observed at 6107 Å in the discharge was assigned to the electronic transition of the phenoxy radical on the basis of the sample gas dependences and the reported low resolution spectrum. The electronic transition frequency of the phenoxy radical was measured. Comparison studies of the thiophenoxy and phenoxy radicals were made with known DIB spectra

  13. Visualizing ignition and combustion of methanol mixtures in a diesel engine; Methanol funmu no glow chakka to nensho no kashika

    Energy Technology Data Exchange (ETDEWEB)

    Inomoto, Y.; Harada, T.; Kusaka, J.; Daisho, Y.; Kihara, R.; Saito, T. [Waseda University, Tokyo (Japan)

    1997-10-01

    A glow-assisted ignition system tends to suffer from poor ignitability and slow flame propagation at low load in a direct-injection diesel engine fueled with methanol. To investigate the ignition process and improve such disadvantages, methanol sprays, their ignition and flames were visualized at high pressures and temperatures using a modified two-stroke engine. The results show that parameters influencing ignition, the location of a glow-plug, swirl level, pressure and temperature are important. In addition, a full kinetics calculation was conducted to predict the delay of methanol mixture ignition by taking into account 39 chemical species and 157 elementary reactions. 3 refs., 9 figs.

  14. Anticipated Guilt for not Helping and Anticipated Warm Glow for Helping are Differently Impacted by Personal Responsibility to Help

    Directory of Open Access Journals (Sweden)

    Arvid Erlandsson

    2016-09-01

    Full Text Available One important motivation for people behaving prosocially is that they want to avoid negative and obtain positive emotions. In the prosocial behavior literature however, the motivations to avoid negative emotions (e.g. guilt and to approach positive emotions (e.g. warm glow are rarely separated, and sometimes even aggregated into a single mood-management construct. The aim of this study was to investigate whether anticipated guilt if not helping and anticipated warm glow if helping are influenced similarly or differently when varying situational factors related to personal responsibility to help. Helping scenarios were created and pilot tests established that each helping scenario could be formulated both in a high-responsibility version and in a low-responsibility version. In Study 1 participants read high-responsibility and low-responsibility helping scenarios, and rated either their anticipated guilt if not helping or their anticipated warm glow if helping (i.e. separate evaluation. Study 2 was similar but here participants rated both their anticipated guilt if not helping and their anticipated warm glow if helping (i.e. joint evaluation. Anticipated guilt was clearly higher in the high-responsibility versions, but anticipated warm glow was unaffected (in Studies 1a and 1b, or even higher in the low-responsibility versions (Study 2. In Studies 3 (where anticipated guilt and warm glow were evaluated separately and 4 (where they were evaluated jointly, personal responsibility to help was manipulated within-subjects. Anticipated guilt was again constantly higher in the high-responsibility versions but for many types of responsibility-manipulations, anticipated warm glow was higher in the low-responsibility versions. The results suggest that we anticipate guilt if not fulfilling our responsibility but that we anticipate warm glow primarily when doing over and beyond our responsibility. We argue that future studies investigating motivations for

  15. The Role of Anode Manufacturing Processes in Net Carbon Consumption

    Directory of Open Access Journals (Sweden)

    Khalil Khaji

    2016-05-01

    Full Text Available Carbon anodes are consumed in electrolysis cells during aluminum production. Carbon consumption in pre-bake anode cells is 400–450 kg C/t Al, considerably higher than the theoretical consumption of 334 kg C/t Al. This excess carbon consumption is partly due to the anode manufacturing processes. Net carbon consumption over the last three years at Emirates Aluminium (EMAL, also known as Emirates Global Aluminium (EGA Al Taweelah was analyzed with respect to anode manufacturing processes/parameters. The analysis indicates a relationship between net carbon consumption and many manufacturing processes, including anode desulfurization during anode baking. Anode desulfurization appears to increase the reaction surface area, thereby helping the Boudouard reaction between carbon and carbon dioxide in the electrolysis zone, as well as reducing the presence of sulfur which could inhibit this reaction. This paper presents correlations noted between anode manufacturing parameters and baked anode properties, and their impact on the net carbon consumption in electrolytic pots. Anode reactivities affect the carbon consumption in the pots during the electrolysis of alumina. Pitch content in anodes, impurities in anodes, and anode desulfurization during baking were studied to find their influence on anode reactivities. The understanding gained through this analysis helped reduce net carbon consumption by adjusting manufacturing processes. For an aluminum smelter producing one million tonnes of aluminum per year, the annual savings could be as much as US $0.45 million for every kg reduction in net carbon consumption.

  16. New High-Energy Nanofiber Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangwu; Fedkiw, Peter; Khan, Saad; Huang, Alex; Fan, Jiang

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. • During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; • In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; • At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  17. Long-term evaluation of hollow screw and hollow cylinder dental implants : Clinical and radiographic results after 10 years

    NARCIS (Netherlands)

    Telleman, Gerdien; Meijer, Henny J. A.; Raghoebar, Gerry M.

    Background: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and

  18. Anodized Ti3SiC2 As an Anode Material for Li-ion Microbatteries.

    Science.gov (United States)

    Tesfaye, Alexander T; Mashtalir, Olha; Naguib, Michael; Barsoum, Michel W; Gogotsi, Yury; Djenizian, Thierry

    2016-07-06

    We report on the synthesis of an anode material for Li-ion batteries by anodization of a common MAX phase, Ti3SiC2, in an aqueous electrolyte containing hydrofluoric acid (HF). The anodization led to the formation of a porous film containing anatase, a small quantity of free carbon, and silica. By varying the anodization parameters, various oxide morphologies were produced. The highest areal capacity was achieved by anodization at 60 V in an aqueous electrolyte containing 0.1 v/v HF for 3 h at room temperature. After 140 cycles performed at multiple applied current densities, an areal capacity of 380 μAh·cm(-2) (200 μA·cm(-2)) has been obtained, making this new material, free of additives and binders, a promising candidate as a negative electrode for Li-ion microbatteries.

  19. High-Energy Radiation from Thunderstorms with ADELE: TGFs, Steps, and Glows

    Science.gov (United States)

    Smith, David M.; Kelley, Nicole; Martinez-McKinney, Forest; Zhang, Zi Yan; Hazelton, Bryna; Grefenstette, Brian; Splitt, Michael; Lazarus, Steven; Ulrich, William; Levine, Steven; Dwyer, Joseph; Schaal, Meagan; Saleh, Ziad; Cramer, Eric; Rassoul, Hamid; Cummer, Steven; Lu, Gaopeng; Shao, Xuan-Min; Ho, Cheng; Blakeslee, Richard

    2011-01-01

    The biggest challenge in the study of high-energy processes in thunderstorms is getting a detector to the vicinity of the electrically active regions of a storm. The Airborne Detector for Energetic Lightning Emissions (ADELE) has been used to detect gamma rays from aircraft above storms and from a storm-chasing van on the ground. In August 2009, ADELE flew above Florida storms in a Gulfstream V jet, detecting the first terrestrial gamma-ray flash (TGF) seen from a plane and continuous glows of high-energy emission above thunderclouds. The presence of these glows suggests that a gradual process of relativistic runaway and feedback may help limit the total amount of charging in thunderstorms, in contrast to the traditional view that only lightning discharges compete with the charging process. The upper limits on TGF emission from intracloud and cloud-to-ground lightning from the ADELE flights demonstrated conclusively that a TGF of the sort seen from space is not associated with most lightning and not necessary to trigger it. In August 2010, observations from a van detected stepped-leader x-ray emission from at least four lightning strikes in ten days of operations. This mode of operation is therefore promising for future observations of the stepping process, although a more varied suite of instrumentation, in particular a flash-distance detector, would be useful. We will report on these results and on future possibilities for ADELE campaigns.

  20. Numerical modeling of a glow discharge through a supersonic bow shock in air

    Science.gov (United States)

    Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.

    2017-03-01

    The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.