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Sample records for hollow anode glow

  1. Low-pressure glow discharge with a hollow cathode

    NASA Astrophysics Data System (ADS)

    Lisovskiy, Valeriy; Bogodielnyi, Illia

    2011-10-01

    We measured the breakdown curves of a dc glow discharge with hollow cathode and flat electrodes in the gap between the electrodes L = 100 mm. At low gas pressure, the left branches of the breakdown curves for the hollow cathode and the flat electrodes are identical. At high gas pressures, the right branch of the breakdown curve of the discharge with a hollow cathode is close to the breakdown curve for the distance between the plane electrodes, equal to the gap between the edge of the plates of the hollow cathode and flat anode. Current-voltage characteristics of the hollow cathode discharge were measured. At low gas pressure discharge is in the high-voltage (electron beam) form with ascending CVC. In the gas pressure range p > 0.1 Torr the discharge first burns in the glow mode. At higher current the discharge goes into the hollow cathode mode, filling the space between the plates, and it has an almost vertical CVC. The transition from a glow discharge mode into a hollow one possesses a hysteresis. At gas pressures p ~ 1 Torr the hollow cathode effect disappears, since the thickness of the cathode layer is small compared with the gap between the plates of the cathode.

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

    SciTech Connect

    Qin, Yu; Xie, Kan; Zhang, Yu; Ouyang, Jiting

    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.

  3. Gas temperature measurements in deuterium hollow cathode glow discharge

    SciTech Connect

    Majstorović, Gordana; Šišović, Nikola

    2016-03-25

    We report results of optical emission spectroscopy measurements of rotational T{sub rot} and translational (gas) temperature of deuterium molecules in a hollow cathode (HC) glow discharge. The rotational temperature of excited electronic state of D{sub 2} was determined from the intensity distribution in the rotational structure of Q branch of the two Fulcher-α diagonal bands: (ν’=ν”=2) and (ν’=ν”=3). The population of excited energy levels, determined from relative line intensities, was used to derive radial rotational temperature distributions as well as gas temperature distribution of deuterium molecule.

  4. Comparative Spectroscopic Temperature Measurements In Hydrogen Hollow Cathode Glow Discharge

    NASA Astrophysics Data System (ADS)

    Majstorovic, G. Lj.; Šišovic, N. M.; Konjevic, N.

    2010-07-01

    We report results of optical emission spectroscopy measurements of rotational Trot and translational temperature Ttr of hydrogen molecules. The light source was hollow cathode glow discharge with titanium cathode operated in hydrogen at low pressure. The rotational temperature of excited electronic states of H2 was determined either from relative line intensities of the R branch of the GK ? B band or from the Q branch of the Fulcher-a diagonal band. The population of excited energy levels, determined from relative line intensities, was used to derive ro-vibronic temperature of the ground state of hydrogen molecule.

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

    SciTech Connect

    Burachevsky, Yu. A. Burdovitsin, V. A.; Oks, E. M.

    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}.

  6. High-pressure dc glow discharges in hollow diamond cathodes

    NASA Astrophysics Data System (ADS)

    Truscott, B. S.; Turner, C.; May, P. W.

    2016-04-01

    We report the generation and characterization of dc helium microdischarges at several times atmospheric pressure in monolithic diamond hollow-cathode devices having cavity diameters on the order of 100 μm. I-V characteristics indicated operation in the glow discharge regime even at nearly 10 atm, while spectroscopic measurements of the N2 C3Πu  →  B3Πg emission returned rotational temperatures always around 420 K, with a pressure-dependent vibrational population distribution. The variation of breakdown voltage with pressure closely followed Paschen’s law, but with offsets in both axes that we tentatively ascribe to strong diffusive loss and a partial thermalization of electron energies under the high pressures considered here.

  7. [Glow Discharge Characteristics of Hollow Needle-Plate Electrode in Atmospheric Pressure Argon].

    PubMed

    Liu, Shu-hua; Jia, Peng-ying; Di, Cong; Li, Xue-chen; Yang, Fan

    2015-09-01

    Atmosphere pressure uniform plasma has the broad application prospect in the industrial field. Using hollow needle cathode-plate anode device excited by direct-current voltage, a uniform and stable glow discharge is generated at atmospheric pressure in ambient air with argon used as working gas. The influence of the experimental parameters (including gas flow rate and the gas gap width) on discharge has been investigated by optical method. It can be found that a glow-discharge plasma column can bridge the two electrodes. The plasma column is uniform, and no filaments can be discerned. Near the plate electrode, the diameter of the plasma column is largest of all positions. The maximal diameter of the plasma column increases with increasing the discharge current or the gas flow rate. Through electrical method, the voltage-current characteristic has been investigated. It has been found that the discharge voltage decreases with increasing the current which is similar with the characteristic of glow discharge in low pressure. It increases with increasing the gas gap width or the gas flow rate. By analyzing the optical emission spectrum scanning from 330 to 450 nm emitted from the direct-current glow discharge, the molecular vibrational temperature and the intensity ratio of spectral lines I391.4/I337.1 have been investigated as functions of the gas flow rate and gas gap width. Results indicate that both the vibrational temperature and the intensity ratio of spectral lines I391.4/I337.1 decrease with increasing the gas flow rate or the gas gap width. In addition, the molecular vibrational temperature and the intensity ratio of spectral lines I391.4/I337.1 have been investigated in spatial resolution along the direction of gas flow (plasma column axial), and give a qualitative analysis as well. It is found that the vibrational temperature and the average electron energy increase with increasing the distance from the hollow needle cathode. These results are important to

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

    PubMed

    Yang, Haiming; Tezuka, Meguru

    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.

  9. A 200 W Hall thruster with hollow indented anode

    NASA Astrophysics Data System (ADS)

    Ding, Yongjie; Sun, Hezhi; Wei, Liqiu; Li, Peng; Su, Hongbo; Peng, Wuji; Yu, Daren

    2017-10-01

    A hollow indented anode is proposed for increasing the neutral gas density in a discharge channel, in order to improve the performance of the thruster. The experimental results show that a hollow indented anode structure can effectively improve the performance, compared to a hollow straight anode under similar operating conditions, in terms of thrust, propellant utilization, ionization rate, and anode efficiency. Furthermore, simulations show that the indented anode can effectively increase the neutral gas density in a discharge channel and on the centerline of the channel, compared to a hollow straight anode. In addition, it can increase the ionization rate in the channel and the pre-ionization in the anode. Therefore, the hollow indented anode could be considered as an important design idea for improving thruster performance.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Hollow Nanostructured Anode Materials for Li-Ion Batteries

    PubMed Central

    2010-01-01

    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. PMID:21076674

  12. Hollow electrode plasma excitation source

    DOEpatents

    Ballou, Nathan E.

    1992-01-01

    A plasma source incorporates a furnace as a hollow anode, while a coaxial cathode is disposed therewithin. The source is located in a housing provided with an ionizable gas such that a glow discharge is produced between anode and cathode. Radiation or ionic emission from the glow discharge characterizes a sample placed within the furnace and heated to elevated temperatures.

  13. Continuous wavelet transform based time-scale and multifractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Nurujjaman, Md.; Narayanan, Ramesh; Iyengar, A. N. Sekar

    2009-10-01

    Continuous wavelet transform (CWT) based time-scale and multifractal analyses have been carried out on the anode glow related nonlinear floating potential fluctuations in a hollow cathode glow discharge plasma. CWT has been used to obtain the contour and ridge plots. Scale shift (or inversely frequency shift), which is a typical nonlinear behavior, has been detected from the undulating contours. From the ridge plots, we have identified the presence of nonlinearity and degree of chaoticity. Using the wavelet transform modulus maxima technique we have obtained the multifractal spectrum for the fluctuations at different discharge voltages and the spectrum was observed to become a monofractal for periodic signals. These multifractal spectra were also used to estimate different quantities such as the correlation and fractal dimension, degree of multifractality, and complexity parameters. These estimations have been found to be consistent with the nonlinear time series analysis.

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

    SciTech Connect

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

    2008-09-07

    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.

  15. Interconnected hollow carbon nanospheres for stable lithium metal anodes.

    PubMed

    Zheng, Guangyuan; Lee, Seok Woo; Liang, Zheng; Lee, Hyun-Wook; Yan, Kai; Yao, Hongbin; Wang, Haotian; Li, Weiyang; Chu, Steven; Cui, Yi

    2014-08-01

    For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼ 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

  16. Interconnected hollow carbon nanospheres for stable lithium metal anodes

    NASA Astrophysics Data System (ADS)

    Zheng, Guangyuan; Lee, Seok Woo; Liang, Zheng; Lee, Hyun-Wook; Yan, Kai; Yao, Hongbin; Wang, Haotian; Li, Weiyang; Chu, Steven; Cui, Yi

    2014-08-01

    For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g-1) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm-2. The Coulombic efficiency improves to ˜99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Role of electrostatic and magnetic electron confinement in a hollow-cathode glow discharge in a nonuniform magnetic field

    SciTech Connect

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

    2015-02-15

    Glow discharge with electron confinement in an electrostatic trap has been studied. The trap is formed by a cylindrical hollow cathode, as well as by a flat target on its bottom and a grid covering its output aperture, both being negatively biased relative to the cathode. At a gas pressure of 0.2–0.4 Pa, the fraction of ions sputtering the target (δ = 0.13) in the entire number of ions emitted by the uniform discharge plasma corresponds to the ratio of the target surface area to the total surface area of the cathode, grid, and target. When a nonuniform magnetic field with force lines passing through the target center (where the magnetic induction reaches 35 mT), as well as through the grid, hollow cathode, and target periphery (where the field lines are arc-shaped), is applied to the trap, its influence on the discharge depends on the magnetic induction B{sub 0} at the target edge. At B{sub 0} = 1 mT, the electrons emitted from the target periphery and drifting azimuthally in the arc-shaped field insignificantly contribute to gas ionization. Nevertheless, since fast electrons that are emitted from the cathode and oscillate inside it are forced by the magnetic field to come more frequently to the target, thereby intensifying gas ionization near the latter, the fraction δ doubles and the plasma density near the target becomes more than twice as high as that near the grid. At B{sub 0} = 6 mT, the contribution of electrons emitted from the target surface to gas ionization near the target grows up and δ increases two more times. At cathode-target voltages in the range of 0–3 kV, the current in the target circuit vanishes as the voltage between the anode and the cathode decreases to zero.

  19. Anomalous Broadening of Balmer H{sub {alpha}} Line in Aluminum and Copper Hollow Cathode Glow Discharges

    SciTech Connect

    Sisovic, N. M.; Majstorovic, G. Lj.; Konjevic, N.

    2008-10-22

    The presented results are concerned with the shape of Balmer alpha line emitted from a low pressure DC glow discharge with aluminum (Al) and copper (Cu) hollow cathode (HC) in pure H{sub 2} and Ar-H{sub 2} gas mixture. The analysis indicates that the line profile represents a convolution of Gaussian profiles resulting from different collision excitation processes.

  20. Investigation of atmospheric pressure glow microdischarge between flat cathode and needle anode in helium and argon

    NASA Astrophysics Data System (ADS)

    Astafiev, Alexander; Belyaev, Vladimir; Zamchii, Roman; Kudryavtsev, Anatoly; Stepanova, Olga; Chen, Zhaoquan

    2016-09-01

    DC atmospheric-pressure glow microdischarge was generated between a flat cathode and needle anode with a diameter of 100 μm in a special chamber with helium or argon. Dependences of discharge parameters on an interelectrode gap was investigated with an original experimental setup based on a movable arm on the hinge joint which allowed changing the gap with a step of 5 μm. The gap was varied from 5 to 700 μm. Discharge current was 1-21 mA. Such discharge cell has a very low interelectrode capacitance and provides increasing the stability of the discharge against arc formation (transition to RC oscillations mode) at low currents of 1 mA. A weak dependence of discharge voltage across the gap was revealed in helium at 100-250 μm between the electrodes (normal discharge). In contrast to this, glow microdischarge in argon has a descending current-voltage characteristic and unstable nature. The discharge voltage depending on the gap changes significantly slower than in helium. According to our estimations, the strength of electrical field of positive glow in argon is 5 times lower than in helium. Saint Petersburg State University (Grant No. 0.37.218.2016).

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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.

  3. An Investigation of the Role of Near-Anode Plasma Conditions on Anode Spot Self-Organization in Atmospheric Pressure DC Glows

    NASA Astrophysics Data System (ADS)

    Kovach, Yao; Foster, John

    2016-09-01

    In previous work, plasma self-organization patterns were experimentally observed on both liquid surface and metal anode surface in atmospheric pressure glows. However, the origin of the self-organized pattern formation is still poorly understood and is currently under study. In this work, it was observed that the discharge current is the dominant parameter controlling the onset of the self-organization of the plasma attachment on a liquid anode. On the other hand, it is observed that interelectrode spacing is the key parameter that controls plasma self-organization on metal anodes. Presented here are experiments aimed at understanding how these parameters control conditions at the anode surface which ultimately result in self-organization. Here we determine the effects of space charge at the anode surface and also estimate the anode fall voltage in response to discharge parameter variations. Additionally, electron microscopy is used to assess anode morphological changes resulting from the self-organization plasma attachments.

  4. Hollow electrode enhanced radio frequency glow plasma and its application to the chemical vapor deposition of microcrystalline silicon

    SciTech Connect

    Tabuchi, Toshihiro; Mizukami, Hiroyuki; Takashiri, Masayuki

    2004-09-01

    A hollow electrode enhanced radio frequency (rf) glow plasma excitation technique and its application to the chemical vapor deposition of microcrystalline silicon films have been studied. In this technique, the reactor has two types of hollow structure. One is a hollow counterelectrode, and the other serves as both a hollow counterelectrode and a hollow rf electrode. The application of these discharge types to semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition of hydrogenated microcrystalline silicon thin films. High crystallinity, photosensitivity and a maximum deposition rate of 6.0 nm/s can all be achieved at plasma excitation frequency of 13.56 MHz and substrate temperature of 300 deg. C. Properties of these plasmas are investigated by observing the plasma emission pattern, optical emission spectrum analysis and electrical parameters of the rf electrode. It is found that the plasma technique using both types of hollow discharge not only results in higher intensity of SiH{sup *} and H{alpha} but also in much smaller self-bias voltage of the rf electrode. Faster processing of device grade hydrogenated microcrystalline silicon films can also be achieved under lower rf power compared to use of the hollow counterelectrode technique alone.

  5. Hollow electrode enhanced radio frequency glow plasma and its application to the chemical vapor deposition of microcrystalline silicon

    NASA Astrophysics Data System (ADS)

    Tabuchi, Toshihiro; Mizukami, Hiroyuki; Takashiri, Masayuki

    2004-09-01

    A hollow electrode enhanced radio frequency (rf) glow plasma excitation technique and its application to the chemical vapor deposition of microcrystalline silicon films have been studied. In this technique, the reactor has two types of hollow structure. One is a hollow counterelectrode, and the other serves as both a hollow counterelectrode and a hollow rf electrode. The application of these discharge types to semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition of hydrogenated microcrystalline silicon thin films. High crystallinity, photosensitivity and a maximum deposition rate of 6.0 nm/s can all be achieved at plasma excitation frequency of 13.56 MHz and substrate temperature of 300°C. Properties of these plasmas are investigated by observing the plasma emission pattern, optical emission spectrum analysis and electrical parameters of the rf electrode. It is found that the plasma technique using both types of hollow discharge not only results in higher intensity of SiH* and Hα but also in much smaller self-bias voltage of the rf electrode. Faster processing of device grade hydrogenated microcrystalline silicon films can also be achieved under lower rf power compared to use of the hollow counterelectrode technique alone.

  6. The design and characteristics of direct current glow discharge atomic emission source operated with plain and hollow cathodes.

    PubMed

    Qayyum, A; Mahmood, M I

    2008-01-07

    A compact direct current glow discharge atomic emission source has been designed and constructed for analytical applications. This atomic emission source works very efficiently at a low-input electrical power. The design has some features that make it distinct from that of the conventional Grimm glow discharge source. The peculiar cathode design offered greater flexibility on size and shape of the sample. As a result the source can be easily adopted to operate in Plain or Hollow Cathode configuration. I-V and spectroscopic characteristics of the source were compared while operating it with plain and hollow copper cathodes. It was observed that with hollow cathode, the source can be operated at a less input power and generates greater Cu I and Cu II line intensities. Also, the intensity of Cu II line rise faster than Cu I line with argon pressure for both cathodes. But the influence of pressure on Cu II lines was more significant when the source is operated with hollow cathode.

  7. Application of hollow anodes in a Hall thruster with double-peak magnetic fields

    NASA Astrophysics Data System (ADS)

    Ding, Yongjie; Sun, Hezhi; Li, Peng; Wei, Liqiu; Su, Hongbo; Peng, Wuji; Li, Hong; Yu, Daren

    2017-08-01

    A low-power Hall thruster was designed with two permanent magnet rings. Unlike conventional Hall thrusters, this one has a symmetrical double-peak magnetic field with a larger gradient. Moreover, the highest magnetic field strength appears in the plume region; hence, the distance from the zero-magnetic region to the channel outlet is shorter than that of other Hall thrusters. This paper presents the law and mechanism of the effect of a U-shaped hollow anode with the front end in the zero-magnetic region and anodes at the first magnetic peak and zero-magnetic point (corresponding to the front and rear end faces of the U-shaped anode, respectively) on the discharge characteristics of the thruster. The study shows that the overall performance of the hollow anode under the same operating conditions is the highest. For the anode at the magnetic peak, although the ionization rate is the highest, most of the ions generated by ionization collide with the walls, causing greater energy loss and minimizing its performance. For the anode at the zero-magnetic point, although its maximum ionization rate is higher than that of the hollow anode, and the power deposition on the walls is slightly smaller, its propellant utilization and voltage utilization are lower than those of the hollow anode; furthermore, its overall performance is poorer than that of the hollow anode because of the short channel and shorter ionization region.

  8. Hollow Nanostructured Metal Silicates with Tunable Properties for Lithium Ion Battery Anodes.

    PubMed

    Yu, Seung-Ho; Quan, Bo; Jin, Aihua; Lee, Kug-Seung; Kang, Soon Hyung; Kang, Kisuk; Piao, Yuanzhe; Sung, Yung-Eun

    2015-11-25

    Hollow nanostructured materials have attracted considerable interest as lithium ion battery electrodes because of their good electrochemical properties. In this study, we developed a general procedure for the synthesis of hollow nanostructured metal silicates via a hydrothermal process using silica nanoparticles as templates. The morphology and composition of hollow nanostructured metal silicates could be controlled by changing the metal precursor. The as-prepared hierarchical hollow nanostructures with diameters of ∼100-200 nm were composed of variously shaped primary particles such as hollow nanospheres, solid nanoparticles, and thin nanosheets. Furthermore, different primary nanoparticles could be combined to form hybrid hierarchical hollow nanostructures. When hollow nanostructured metal silicates were applied as anode materials for lithium ion batteries, all samples exhibited good cyclic stability during 300 cycles, as well as tunable electrochemical properties.

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

    PubMed

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

    2013-06-01

    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.

  10. Correlation between reversion of signs of the electric field in the near-cathode plasma and anode fall potential in a short DC glow discharge

    NASA Astrophysics Data System (ADS)

    Prokhorova, E. I.; Kudryavtsev, A. A.; Platonov, A. A.; Slyshov, A. G.

    2017-07-01

    Relatively simple probe and optical experiments were performed, confirming the presence of two main scenarios for the formation of the longitudinal characteristics of a short (without positive column) glow discharge. 1. At low pressures, when there is a single point of sign reverse of the electric field at the maximum of the plasma density, the anode fall is negative and the magnitude of the anode fall is small, there is no ionization and the anode area is dark. 2. Upon an increase in pressure, two points of field reversal are to be expected, the sign of the anode fall is positive and the anode fall of potential is comparable to the gas ionization potential; therefore, the intensive ionization directly at the anode, which glows brightly, takes place.

  11. The Effect of Anode Material and Secondary Gas Injection on Self-organized Patterns in Atmospheric Pressure Glows

    NASA Astrophysics Data System (ADS)

    Kovach, Yao; Foster, John

    2015-09-01

    Plasma self-organization on anode surfaces in DC glow discharges remains poorly understood. This effort aims to elucidate the nature of self-organization through the study of resulting patterns on both liquid and metal electrode surfaces. Self-organization pattern formation and behavior were studied as a function of inter-electrode spacing, electrode material type, gas composition and gas flow rate using emission spectroscopy and fast camera imaging. The response of the patterns to variation in these parameters is reported. These results are used as a basis for speculating upon the underlying physical processes that give rise to the self-organization. NSF CBET 1336375.

  12. Stress-modulated driving force for lithiation reaction in hollow nano-anodes

    NASA Astrophysics Data System (ADS)

    Jia, Zheng; Li, Teng

    2015-02-01

    Lithiation of a crystalline silicon anode proceeds by the movement of an atomically sharp reaction front that separates a pristine crystalline phase and a fully-lithiated amorphous phase. The velocity of the reaction front is limited rather by the reaction rate at the lithiation front than by the diffusivity of lithium ions in the amorphous lithiated phase. Experiments on solid nanoparticle/nanowire silicon anodes show an initial rapid advancing of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front propagation. Lithiation-induced stresses during lithiation are attributed to alter the driving force of lithiation and thus result in the observed slowing of reaction front. Recent experiments on lithiation of hollow silicon nanowires reveals similar slowing of reaction front, however, quantitative study of the effect of lithiation-associated stress on the driving force of lithiation still lacks so far. Here, through chemo-mechanical modeling and theoretical formulation, we present a comprehensive study on lithiation-induced stress field and its contribution to the driving force of lithiation reaction in hollow silicon nanowire anodes. We show that hollow silicon nano-anodes could be fully lithiated with lower stress-induced energy barrier than solid silicon nano-anodes. As a result, it is expected that the hollow nanowires and nanoparticles may serve as an optimal structural design for high-performance anodes of lithium-ion batteries. Results from the present study shed light on a number of open questions of lithiation kinetics of silicon-based anodes in recent literature and offer insight on developing silicon-based anodes with high charging capacity and high charging rate.

  13. Doppler spectroscopy of hydrogen Balmer lines in a hollow cathode glow discharge in ammonia and argon-ammonia mixture

    SciTech Connect

    Sisovic, N. M.; Konjevic, N.

    2008-11-15

    The results of Doppler spectroscopy of hydrogen Balmer lines from a stainless steel (SS) and copper (Cu) hollow cathode (HC) glow discharge in ammonia and argon-ammonia mixture are reported. The experimental profiles in ammonia discharge are fitted well by superposing three Gaussian profiles. The half widths, in energy units, of narrow and medium Gaussians are in the ranges 0.3-0.4 eV and 3-4 eV, respectively, for both hollow cathodes what is expected on the basis of earlier electron beam{yields}NH{sub 3} experiments. The half widths of the largest Gaussian in ammonia are 46 and 55 eV for SS and Cu HC, respectively. In argon-ammonia discharge, three Gaussians are also required to fit experimental profiles. While half widths of narrow and medium Gaussians are similar to those in ammonia, the half widths of the largest Gaussians are 35 and 42 eV for SS and Cu HC, respectively. The half widths of the largest Gaussians in ammonia and in argon-ammonia mixture indicate the presence of excessive Doppler broadening.

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

    PubMed

    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. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Hollow Core-Shell Structured Porous Si-C Nanocomposites for Li-Ion Battery Anodes

    SciTech Connect

    Li, Xiaolin; Meduri, Praveen; Chen, Xilin; Qi, Wen N.; Engelhard, Mark H.; Xu, Wu; Ding, Fei; Xiao, Jie; Wang, Wei; Wang, Chong M.; Zhang, Jiguang; Liu, Jun

    2012-06-14

    Hollow core-shell structured porous Si-C nanocomposites with void space up to tens of nanometers are designed to accommodate the volume expansion during lithiation for high-performance Li-ion battery anodes. An initial capacity of {approx}760 mAh/g after formation cycles (based on the entire electrode weight) with {approx}86% capacity retention over 100 cycles is achieved at a current density of 1 A/g. Good rate performance is also demonstrated.

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

    PubMed

    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.

  17. Silicon hollow sphere anode with enhanced cycling stability by a template-free method

    NASA Astrophysics Data System (ADS)

    Chen, Song; Chen, Zhuo; Luo, Yunjun; Xia, Min; Cao, Chuanbao

    2017-04-01

    Silicon is a promising alternative anode material since it has a ten times higher theoretical specific capacity than that of a traditional graphite anode. However, the poor cycling stability due to the huge volume change of Si during charge/discharge processes has seriously hampered its widespread application. To address this challenge, we design a silicon hollow sphere nanostructure by selective etching and a subsequent magnesiothermic reduction. The Si hollow spheres exhibit enhanced electrochemical properties compared to the commercial Si nanoparticles. The initial discharge and charge capacities of the Si hollow sphere anode are 2215.8 mAh g-1 and 1615.1 mAh g-1 with a high initial coulombic efficiency (72%) at a current density of 200 mA g-1, respectively. In particular, the reversible capacity is 1534.5 mAh g-1 with a remarkable 88% capacity retention against the second cycle after 100 cycles, over four times the theoretical capacity of the traditional graphite electrode. Therefore, our work demonstrates the considerable potential of silicon structures for displacing commercial graphite, and might open up new opportunities to rationally design various nanostructured materials for lithium ion batteries.

  18. Silicon hollow sphere anode with enhanced cycling stability by a template-free method.

    PubMed

    Chen, Song; Chen, Zhuo; Luo, Yunjun; Xia, Min; Cao, Chuanbao

    2017-04-21

    Silicon is a promising alternative anode material since it has a ten times higher theoretical specific capacity than that of a traditional graphite anode. However, the poor cycling stability due to the huge volume change of Si during charge/discharge processes has seriously hampered its widespread application. To address this challenge, we design a silicon hollow sphere nanostructure by selective etching and a subsequent magnesiothermic reduction. The Si hollow spheres exhibit enhanced electrochemical properties compared to the commercial Si nanoparticles. The initial discharge and charge capacities of the Si hollow sphere anode are 2215.8 mAh g(-1) and 1615.1 mAh g(-1) with a high initial coulombic efficiency (72%) at a current density of 200 mA g(-1), respectively. In particular, the reversible capacity is 1534.5 mAh g(-1) with a remarkable 88% capacity retention against the second cycle after 100 cycles, over four times the theoretical capacity of the traditional graphite electrode. Therefore, our work demonstrates the considerable potential of silicon structures for displacing commercial graphite, and might open up new opportunities to rationally design various nanostructured materials for lithium ion batteries.

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

    NASA Astrophysics Data System (ADS)

    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

  20. Hollow Cobalt Selenide Microspheres: Synthesis and Application as Anode Materials for Na-Ion Batteries.

    PubMed

    Ko, You Na; Choi, Seung Ho; Kang, Yun Chan

    2016-03-01

    The electrochemical properties of hollow cobalt oxide and cobalt selenide microspheres are studied for the first time as anode materials for Na-ion batteries. Hollow cobalt oxide microspheres prepared by one-pot spray pyrolysis are transformed into hollow cobalt selenide microspheres by a simple selenization process using hydrogen selenide gas. Ultrafine nanocrystals of Co3O4 microspheres are preserved in the cobalt selenide microspheres selenized at 300 °C. The initial discharge capacities for the Co3O4 and cobalt selenide microspheres selenized at 300 and 400 °C are 727, 595, and 586 mA h g(-1), respectively, at a current density of 500 mA g(-1). The discharge capacities after 40 cycles for the same samples are 348, 467, and 251 mA h g(-1), respectively, and their capacity retentions measured from the second cycle onward are 66, 91, and 50%, respectively. The hollow cobalt selenide microspheres have better rate performances than the hollow cobalt oxide microspheres.

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

    PubMed

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

    2017-02-27

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Effect of nickel impregnated hollow fiber anode for micro tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    He, Beibei; Ling, Yihan; Xu, Jianmei; Zhao, Ling; Cheng, Jigui

    2014-07-01

    A micro tubular solid oxide fuel cells (MT-SOFCs) with a cell configuration of Ni impregnated Ni-Gd0.1Ce0.9O1.95 (GDC)/GDC/La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)-GDC has been prepared by the phase inversion and impregnation technique. A special asymmetrical structure consisting of a sponge-like layer and a finger-like porous layer for hollow fiber anode is obtained by the phase inversion. Fine Ni specie particles are then coated on the surface of anode using impregnation method. The enhancement in electronic conductivity of anode by Ni modification is beneficial to current collection of MT-SOFCs. Meanwhile, the catalytic activity of anode is also improved due to the introduction of Ni nano-particles. Thus, the Ni modified MT-SOFCs exhibit high power densities, such as 0.69 W cm-2 at 600 °C. The encouraging results demonstrate that the Ni impregnation is an effective way to improve anode microstructure of MT-SOFCs.

  4. Hollow Structured Silicon Anodes with Stabilized Solid Electrolyte Interphase Film for Lithium-Ion Batteries.

    PubMed

    Lv, Qiuliang; Liu, Yuan; Ma, Tianyi; Zhu, Wentao; Qiu, Xinping

    2015-10-28

    Silicon has been considered as a promising anode material for the next generation of lithium-ion batteries due to its high specific capacity. Its huge volume expansion during the alloying reaction with lithium spoils the stability of the interface between electrode and electrolyte, resulting in capacity degradation. Herein, we synthesized a novel hollow structured silicon material with interior space for accumulating the volume change during the lithiation. The as-prepared material shows excellent cycling stability, with a reversible capacity of ∼1650 m Ah g(-1) after 100 cycles, corresponding to 92% retention. The electrochemical impedance spectroscopy and differential scanning calorimetry were carried out to monitor the growth of SEI film, and the results confirm the stable solid electrolyte interphase film on the surface of hollow structured silicon.

  5. Hollow carbon-nanotube/carbon-nanofiber hybrid anodes for Li-ion batteries.

    PubMed

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

    2013-11-06

    By a novel in situ chemical vapor deposition, activated N-doped hollow carbon-nanotube/carbon-nanofiber composites are prepared having a superhigh specific Brunauer–Emmett–Teller (BET) surface area of 1840 m(2) g(–1) and a total pore volume of 1.21 m(3) g(–1). As an anode, this material has a reversible capacity of ~1150 mAh g(–1) at 0.1 A g(–1) (0.27 C) after 70 cycles. At 8 A g(–1) (21.5 C), a capacity of ~320 mAh g(–1) fades less than 20% after 3500 cycles, which makes it a superior anode material for a Li-ion battery.

  6. Electrochemical engineering of hollow nanoarchitectures: pulse/step anodization (Si, Al, Ti) and their applications.

    PubMed

    Wang, Kaiying; Liu, Guohua; Hoivik, Nils; Johannessen, Erik; Jakobsen, Henrik

    2014-03-07

    Hollow nanoarchitectured materials with straight channels play a crucial role in the fields of renewable energy, environment and biotechnology due to their one-dimensional morphology and extraordinary properties. The current challenge is the difficulty on tailoring hollow nanoarchitectures with well-controlled morphology at a relatively low cost. As a conventional technique, electrochemistry exhibits its unique advantage on machining nanostructures. In this review, we present the progress of electrochemistry as a valuable tool in construction of novel hollow nanoarchitectures through pulse/step anodization, such as surface pre-texturing, modulated, branched and multilayered pore architectures, and free-standing membranes. Basic principles for electrochemical engineering of mono- or multi-ordered nanostructures as well as free-standing membranes are extracted from specific examples (i.e. porous silicon, aluminum and titanium oxide). The potential of such nanoarchitectures are further demonstrated for the applications of photovoltaics, water splitting, organic degradation, nanostructure templates, biosensors and drug release. The electrochemical techniques provide a powerful approach to produce nanostructures with morphological complexity, which could have far-reaching implications in the design of future nanoscale systems.

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

    PubMed

    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.

  8. Process for Testing Compaction of a Swaged Heater for an Anode Sub-Assembly of a Hollow Cathode Assembly

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    A process for testing compaction of a swaged heater for an anode sub-assembly of a Hollow Cathode Assembly (HCA), in which a test sample is cleaned, its mass measured before and after immersion in kerosene for 24 hours, and a compaction percentage calculated. A swaged heater is rejected if the compaction percentage exceeds 84%, plus or minus 4%.

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

    SciTech Connect

    Sasidharan, Manickam; Gunawardhana, Nanda; Yoshio, Masaki; Nakashima, Kenichi

    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.

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

    PubMed

    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

    2013-04-07

    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.

  11. MoO2@carbon hollow microspheres with tunable interiors and improved lithium-ion battery anode properties.

    PubMed

    Liu, Xiaolin; Ji, Wenxu; Liang, Jiyuan; Peng, Luming; Hou, Wenhua

    2014-10-14

    MoO2 hollow microspheres with tunable inner space have been synthesized through a hydrothermal process using MoO3 microbelts instead of bulk MoO3 as the precursor. It is found that the reactant morphology has a great impact on the product morphology and the inner space can be tuned by changing the amount of NaOH aqueous solution. An interesting evolutional process from MoO3 microbelts through a rose-like intermediate to MoO2 hollow microspheres has been clearly observed, and thus the possible formation mechanism is revealed. One layer of amorphous carbon has been subsequently coated on the surface of MoO2 hollow microspheres through a simple hydrothermal approach followed by annealing in argon. As the anode material for lithium ion batteries, MoO2@C hollow microspheres manifest excellent lithium-storage properties, such as high capacity (677 mA h g(-1)) and good cycling stability (negligible capacity fading even after 80 cycles). The significantly enhanced performance of MoO2@C hollow microspheres can be attributed to its unique structures, such as nanoscaled primary building blocks, carbon coating, hollow structure, and especially the synergy between the carbon coating and hollow structure.

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

    NASA Technical Reports Server (NTRS)

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

    NASA Astrophysics Data System (ADS)

    Liu, Jason; Sears, Jason; McMahon, Matt; Higginson, Drew; Link, Anthony; Schmidt, Andrea

    2016-10-01

    The dense plasma focus (DPF) is a classic Z-pinch plasma device that has been long studied as a copious source of various types of radiation. 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. Here we present a novel technique of seeding the m = 0 instability by varying the anode's hollow inner diameter. As the plasma sheath moves along this hollow anode structure, a low density perturbation is formed and this seeds the instability. Dynamics of the low density perturbation and seeding of the m = 0 instability are studied in detail with fully kinetic plasma simulations performed in the LSP particle-in-cell code on a 60 kA device. It is discovered in the simulations that the neutron yield of the DPF may be significantly improved and made more consistent by employing an anode geometry with an appropriate inner hollow diameter. Prepared by LLNL under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

  14. Hollow Porous SiO2 Nanocubes Towards High-performance Anodes for Lithium-ion Batteries

    PubMed Central

    Yan, Nan; Wang, Fang; Zhong, Hao; Li, Yan; Wang, Yu; Hu, Lin; Chen, Qianwang

    2013-01-01

    The high theoretical capacity and low discharge potential of silicon have attracted much attention on Si-based anodes. Herein, hollow porous SiO2 nanocubes have been prepared via a two-step hard-template process and evaluated as electrode materials for lithium-ion batteries. The hollow porous SiO2 nanocubes exhibited a reversible capacity of 919 mAhg−1 over 30 cycles. The reasonable property could be attributed to the unique hollow nanostructure with large volume interior and numerous crevices in the shell, which could accommodate the volume change and alleviate the structural strain during Li ions' insertion and extraction, as well as allow rapid access of Li ions during charge/discharge cycling. It is found that the formation of irreversible or reversible lithium silicates in the anodes determines the capacity of a deep-cycle battery, fast transportation of Li ions in hollow porous SiO2 nanocubes is beneficial to the formation of Li2O and Si, contributing to the high reversible capacity. PMID:23535780

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  17. High-current diode with ferroelectric plasma source-assisted hollow anode

    SciTech Connect

    Vekselman, V.; Gleizer, J. Z.; Yatom, S.; Gurovich, V. Tz.; Krasik, Ya. E.

    2010-11-15

    The operation of a ferroelectric plasma source-assisted hollow anode (HA) electron source in a vacuum diode powered by an {approx}200 kV and {approx}400 ns pulsed generator was studied using time- and space-resolved laser induced fluorescence diagnostics. It was found that the plasma ion ''temperature'' in the vicinity of the HA output grid increases up to {approx}15 eV during the accelerating pulse, which is consistent with a model of the potential screening of the grid by the randomly moving ions [Phys. Plasmas 13, 073506 (2006)]. Also it was shown that the increase in the HA plasma potential up to several kilovolts because of the appearance of a noncompensated ion charge in the HA bulk plasma due to electrons fast extraction, leads to explosive emission centers being generated at the HA grid and to nonuniformity in the cross-sectional electron beam current density. Finally, the plasma prefilled mode of diode operation was studied using a simple one-dimensional model of the plasma erosion and the HA plasma electron heating by energetic ions was considered.

  18. Graphitic Carbon Conformal Coating of Mesoporous TiO2 Hollow Spheres for High-Performance Lithium Ion Battery Anodes.

    PubMed

    Liu, Hao; Li, Wei; Shen, Dengke; Zhao, Dongyuan; Wang, Guoxiu

    2015-10-14

    Rational design and controllable synthesis of TiO2 based materials with unique microstructure, high reactivity, and excellent electrochemical performance for lithium ion batteries are crucially desired. In this paper, we developed a versatile route to synthesize hollow TiO2/graphitic carbon (H-TiO2/GC) spheres with superior electrochemical performance. The as-prepared mesoporous H-TiO2/GC hollow spheres present a high specific surface area (298 m(2) g(-1)), a high pore volume (0.31 cm(3) g(-1)), a large pore size (∼5 nm), well-defined hollow structure (monodispersed size of 600 nm and inner diameter of ∼400 nm, shell thickness of 100 nm), and small nanocrystals of anatase TiO2 (∼8 nm) conformably encapsulated in ultrathin graphitic carbon layers. As a result, the H-TiO2/GC hollow spheres achieve excellent electrochemical reactivity and stability as an anode material for lithium ion batteries. A high specific capacity of 137 mAh g(-1) can be achieved up to 1000 cycles at a current density of 1 A g(-1) (5 C). We believe that the mesoporous H-TiO2/GC hollow spheres are expected to be applied as a high-performance electrode material for next generation lithium ion batteries.

  19. Hollow Core-Shell SnO2/C Fibers as Highly Stable Anodes for Lithium-Ion Batteries.

    PubMed

    Zhou, Dan; Song, Wei-Li; Fan, Li-Zhen

    2015-09-30

    Given their competitive prospects for energy storage, lithium-ion batteries (LIBs) have attracted ever-intensive research interest. However, the large volume changes during cycling and structural pulverization significantly hinder the cycling stability and high capacity for lithium-alloy electrodes. Herein, novel one-dimensional (1D) hollow core-shell SnO2/C fibers were synthesized by facile coaxial electrospinning. The as-prepared fibers that possess sufficient hollow voids and nanosized SnO2 particles on the inner shell are able to serve as an anode in LIBs. The results suggest a reversible capacity of 1002 mAh g(-1) (for the initial cycle at 100 mA g(-1)), excellent rate capability, and a highly stable cycling performance with a discharge capacity of 833 mAh g(-1) after 500 cycles at 600 mA g(-1). The superior electrochemical performance is attributed to the unique hollow core-shell structure, which offers sufficient voids for alleviating the volume changes of SnO2 nanoparticles during lithiation/delithiation processes. The promising strategies and associated opportunities here demonstrate great potential in the fabrication of advanced anode materials for long-life LIBs.

  20. Hydrothermal-Assisted Sintering Strategy Towards Porous- and Hollow-Structured LiNb3O8 Anode Material

    NASA Astrophysics Data System (ADS)

    Zhai, Haifa; Liu, Hairui; Li, Hongjing; Zheng, Liuyang; Hu, Chunjie; Zhang, Xiang; Li, Qiling; Yang, Jien

    2017-07-01

    Porous- and hollow-structured LiNb3O8 anode material was prepared by a hydrothermal-assisted sintering strategy for the first time. The phase evolution was studied, and the formation mechanism of the porous and hollow structure was proposed. The formation of the unique structure can be attributed to the local existence of liquid phase because of the volatilization of Li element. As the anode material, the initial discharge capacity is 285.1 mAhg-1 at 0.1 C, the largest discharge capacity reported so far for LiNb3O8. Even after 50 cycles, the reversible capacity can still maintain 77.6 mAhg-1 at 0.1 C, about 2.5 times of that of LiNb3O8 samples prepared by traditional solid-state methods. The significant improvement of Li storage capacity can be attributed to the special porous and hollow structure, which provides a high density of active sites and short parallel channels for fast intercalation of Li+ ions through the surface.

  1. Study of nonlinear oscillations in a glow discharge plasma using empirical mode decomposition and Hilbert Huang transform

    SciTech Connect

    Wharton, A. M.; Sekar Iyengar, A. N.; Janaki, M. S.

    2013-02-15

    Hilbert Huang transform (HHT) based time series analysis was carried out on nonlinear floating potential fluctuations obtained from hollow cathode glow discharge plasma in the presence of anode glow. HHT was used to obtain contour plots and the presence of nonlinearity was studied. Frequency shift with time, which is a typical nonlinear behaviour, was detected from the contour plots. Various plasma parameters were measured and the concepts of correlation coefficients and the physical contribution of each intrinsic mode function have been discussed. Physically important quantities such as instantaneous energy and their uses in studying physical phenomena such as intermittency and non-stationary data have also been discussed.

  2. Confined Solid Electrolyte Interphase Growth Space with Solid Polymer Electrolyte in Hollow Structured Silicon Anode for Li-Ion Batteries.

    PubMed

    Ma, Tianyi; Yu, Xiangnan; Cheng, Xiaolu; Li, Huiyu; Zhu, Wentao; Qiu, Xinping

    2017-04-19

    Silicon anodes for lithium-ion batteries are of much interest owing to their extremely high specific capacity but still face some challenges, especially the tremendous volume change which occurs in cycling and further leads to the disintegration of electrode structure and excessive growth of solid electrolyte interphase (SEI). Here, we designed a novel approach to confine the inward growth of SEI by filling solid polymer electrolyte (SPE) into pores of hollow silicon spheres. The as-prepared composite delivers a high specific capacity of more than 2100 mAh g(-1) and a long-term cycle stability with a reversible capacity of 1350 mAh g(-1) over 500 cycles. The growing behavior of SEI was investigated by electrochemical impedance spectroscopy and differential scanning calorimetry, and the results revealed that SPE occupies the major space of SEI growth and thus confines its excessive growth, which significantly improves cycle performance and Coulombic efficiency of cells embracing hollow silicon spheres.

  3. Facile synthesis of hollow Sn-Co@PMMA nanospheres as high performance anodes for lithium-ion batteries via galvanic replacement reaction and in situ polymerization

    NASA Astrophysics Data System (ADS)

    Yu, Xiaohui; Jiang, Anni; Yang, Hongyan; Meng, Haowen; Dou, Peng; Ma, Daqian; Xu, Xinhua

    2015-08-01

    Polymethyl methacrylate (PMMA)-coated hollow Sn-Co nanospheres (Sn-Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn-Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn-Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g-1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn-Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries.

  4. Double layer in a cylindrical hollow-cathode discharge

    SciTech Connect

    Abu-Hashem, A.; Abd Al-Halim, M. A. Hassouba, M. A.; Masoud, M. M.

    2010-03-15

    A dc cylindrical coaxial glow discharge with an inner grid anode has been studied. The region between the two electrodes is seen dark, while a brightly glowing region forms inside the grid anode up to the center. The current-voltage characteristic of a dc cylindrical glow discharge in nitrogen is similar to that of a normal glow discharge, while the normal glow discharge voltage decreases with increasing pressure. The minimum plasma potentials are observed in the hollow cathode region due to the accumulation of electrons at the back of the grid anode. At the center, some of the passed electrons are converged, so their potential is decreased. These electrons have a sufficient time to be redistributed to form one group with a Maxwellian electron energy distribution function. The electron temperature measured by electric probes varies from 1.6 to 3.6 eV, while the plasma density varies from 3.9 x 10{sup 16} to 7 x 10{sup 13} m{sup -3}, depending on the discharge current and probe position. The plasma density increases as the electrons move radially from the grid toward the central region, while their temperature decreases.

  5. Formation of ZnMn2O4 ball-in-ball hollow microspheres as a high-performance anode for lithium-ion batteries.

    PubMed

    Zhang, Genqiang; Yu, Le; Wu, Hao Bin; Hoster, Harry E; Lou, Xiong Wen David

    2012-09-04

    Novel ZnMn(2)O(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(2)O(4) ball-in-ball hollow microspheres show significantly enhanced electrochemical performance with high capacity, excellent cycling stability and good rate capability. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Sensitive Determination of Cd in Small-Volume Samples by Miniaturized Liquid Drop Anode Atmospheric Pressure Glow Discharge Optical Emission Spectrometry.

    PubMed

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

    2017-06-06

    A novel liquid drop anode (LDA) direct current atmospheric pressure glow discharge (dc-APGD) system was applied for direct determination of Cd in liquid microsamples (50 μL) by optical emission spectrometry (OES). The microdischarge was generated in open-to-air atmosphere between a solid pin type tungsten cathode and a liquid drop placed on a graphite disk anode. The arrangement of the graphite disk placed on a PTFE chip platform as well as the solid pin type cathode was simple and robust. The limit of detection (LOD) of Cd for the developed LDA-APGD-OES method was 0.20-0.40 μg L(-1), while precision (as the relative standard deviation for the repeated measurements) was within 2-5%. By using the liquid drop of 50 μL, the linearity range of 1-1000 μg L(-1) was achieved. The effect of addition of the low-molecular weight (LMW) organic compounds, easily ionized elements (EIEs), i.e., Ca, K, Mg, and Na, as well as the foreign ions (Al, Cu, Fe, Mn, Zn) to the solution on the in situ atomization and excitation processes occurred during operation of the LDA-APGD system, and the response of Cd was studied. Validation of the proposed method was demonstrated by analysis of Lobster hepatopancreas (TORT-2), pig kidney (ERM-BB186), and groundwater (ERM-CA615) certified reference materials (CRMs) and recoveries of Cd from water samples spiked with 25 μg L(-1) of Cd. Very good agreement between the found and certified values of Cd in the CRMs (the recoveries were within the range of 96.3-99.6%) indicated trueness of the method and its reliability for determination of traces of Cd. In the case of the spiked water samples, the recoveries obtained were in the range from 95.2 to 99.5%.

  7. Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

    PubMed Central

    Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

    2015-01-01

    Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al2O3) core-shell films obtained by the deposition of Si and Al2O3 on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g−1 after 100 cycles at a current density of 1 A g−1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement. PMID:25564245

  8. Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries.

    PubMed

    Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

    2015-01-07

    Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al₂O₃) core-shell films obtained by the deposition of Si and Al₂O₃ on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g(-1) after 100 cycles at a current density of 1 A g(-1) with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement.

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

    PubMed

    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 m

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

    NASA Astrophysics Data System (ADS)

    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

  11. Experimental Studies of Anode Sheath Phenomena in a Hall Thruster Discharge

    SciTech Connect

    L. Dorf; Y. Raitses; N.J. Fisch

    2004-12-17

    Both electron-repelling and electron-attracting anode sheaths in a Hall thruster were characterized by measuring the plasma potential with biased and emissive probes [L. Dorf, Y. Raitses, V. Semenov, and N.J. Fisch, Appl. Phys. Let. 84 (2004) 1070]. In the present work, two-dimensional structures of the plasma potential, electron temperature, and plasma density in the near-anode region of a Hall thruster with clean and dielectrically coated anodes are identified. Possible mechanisms of anode sheath formation in a Hall thruster are analyzed. The path for current closure to the anode appears to be the determining factor in the anode sheath formation process. The main conclusion of this work is that the anode sheath formation in Hall thrusters differs essentially from that in the other gas discharge devices, like a glow discharge or a hollow anode, because the Hall thruster utilizes long electron residence times to ionize rather than high neutral pressures.

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

    PubMed

    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.

  13. Periodic organosilica hollow nanospheres as anode materials for lithium ion rechargeable batteries.

    PubMed

    Sasidharan, Manickam; Nakashima, Kenichi; Gunawardhana, Nanda; Yokoi, Toshiyuki; Ito, Masanori; Inoue, Masamichi; Yusa, Shin-ichi; Yoshio, Masaki; Tatsumi, Takashi

    2011-11-01

    Polymeric micelles with core-shell-corona architecture have been found to be the efficient colloidal templates for synthesis of periodic organosilica hollow nanospheres over a broad pH range from acidic to alkaline media. In alkaline medium, poly (styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride-b-ethylene oxide) (PS-PMAPTAC-PEO) micelles yield benzene-silica hollow nanospheres with molecular scale periodicity of benzene groups in the shell domain of hollow particles. Whereas, an acidic medium (pH 4) produces diverse hollow particles with benzene, ethylene, and a mixture of ethylene and dipropyldisulfide bridging functionalities using poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) micelles. These hollow particles were thoroughly characterized by powder X-ray diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TG/DTA), Fourier transformation infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), magic angle spinning-nuclear magnetic resonance ((29)Si MAS NMR and (13)CP-MAS NMR), Raman spectroscopy, and nitrogen adsorption/desorption analyses. The benzene-silica hollow nanospheres with molecular scale periodicity in the shell domain exhibit higher cycling performance of up to 300 cycles in lithium ion rechargeable batteries compared with micron-sized dense benzene-silica particles.

  14. A bubble-template approach for assembling Ni-Co oxide hollow microspheres with an enhanced electrochemical performance as an anode for lithium ion batteries.

    PubMed

    Ding, Caihua; Yan, Dong; Zhao, Yongjie; Zhao, Yuzhen; Zhou, Heping; Li, Jingbo; Jin, Haibo

    2016-10-07

    Although significant advancements in the preparation of metal oxide hollow structures have been achieved, most synthesis routes have some complicated aspects such as requiring a hard-template, multistep procedures or other special reagents. This paper proposes a green and facile bubble-template approach to synthesize and organize Ni-Co hollow microspheres. The entire formation mechanism for the hollow spherical structures, including integration for nucleation, morphological tailoring and an Ostwald ripening process, has been elucidated based on time-dependent observations. The Ni-Co hollow microspheres revealed an excellent cycling stability (730 mA h g(-1) even after 140 cycles at 300 mA g(-1)) and good rate capability when evaluated as an anode material for lithium ion batteries (LIBs). The excellent electrochemical performance can be attributed to the rational design and organization of the hollow structures, which offer a large void space for accommodating volume changes, shorten the diffusion path for Li ions and electron transfer, as well as increase the contact area between the electrodes and electrolyte. Moreover, the synergistic effects of the nickel and cobalt ions with different lithiation potentials allowed the volume change to occur in a stepwise manner. The bubble-template strategy was convenient and very effective for constructing the hollow structures, and if well engineered, it could be extended to the synthesis of other advanced metal oxide anode materials for high energy storage devices and many other applications.

  15. Powerful glow discharge excilamp

    DOEpatents

    Tarasenko, Victor F.; Panchenko, Aleksey N.; Skakun, Victor S.; Sosnin, Edward A.; Wang, Francis T.; Myers, Booth R.; Adamson, Martyn G.

    2002-01-01

    A powerful glow discharge lamp comprising two coaxial tubes, the outer tube being optically transparent, with a cathode and anode placed at opposite ends of the tubes, the space between the tubes being filled with working gas. The electrodes are made as cylindrical tumblers placed in line to one other in such a way that one end of the cathode is inserted into the inner tube, one end of the anode coaxially covers the end of the outer tube, the inner tube penetrating and extending through the anode. The increased electrodes' surface area increases glow discharge electron current and, correspondingly, average radiation power of discharge plasma. The inner tube contains at least one cooling liquid tube placed along the axis of the inner tube along the entire lamp length to provide cathode cooling. The anode has a circumferential heat extracting radiator which removes heat from the anode. The invention is related to lighting engineering and can be applied for realization of photostimulated processes under the action of powerful radiation in required spectral range.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Design and initial results from a kilojoule level Dense Plasma Focus with hollow anode and cylindrically symmetric gas puff.

    PubMed

    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 10(7) 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.

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

    SciTech Connect

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

    2014-01-15

    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 10{sup 7} 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.

  19. Glowing Veggies.

    ERIC Educational Resources Information Center

    Scharlin, Pirketta; And Others

    1996-01-01

    Extends the work of Weimer and Battino in electrical conductivity demonstrations creating "glowing" vegetables (see article this issue) to other vegetables and the spectra generated by other elements other than the sodium in pickle brines. Describes a study on the effect of concentration and voltage on glow intensity. (MKR)

  20. Glowing Veggies.

    ERIC Educational Resources Information Center

    Scharlin, Pirketta; And Others

    1996-01-01

    Extends the work of Weimer and Battino in electrical conductivity demonstrations creating "glowing" vegetables (see article this issue) to other vegetables and the spectra generated by other elements other than the sodium in pickle brines. Describes a study on the effect of concentration and voltage on glow intensity. (MKR)

  1. Si nanoparticles encapsulated in elastic hollow carbon fibres for Li-ion battery anodes with high structural stability

    NASA Astrophysics Data System (ADS)

    Fang, Shan; Shen, Laifa; Tong, Zhenkun; Zheng, Hao; Zhang, Fang; Zhang, Xiaogang

    2015-04-01

    Silicon has a large specific capacity which is an order of magnitude beyond that of conventional graphite, making it a promising anode material for lithium ion batteries. However, the large volume changes (~300%) during cycling caused material pulverization and instability of the solid-electrolyte interphase resulting in poor cyclability which prevented its commercial application. Here, we have prepared a novel one-dimensional core-shell nanostructure in which the Si nanoparticles have been confined within hollow carbon nanofibres. Such a unique nanostructure exhibits high conductivity and facile ion transport, and the uniform pores within the particles which are generated during magnesiothermic reduction can serve as a buffer zone to accommodate the large volume changes of Si during electrochemical lithiation. Owing to these advantages, the composite shows high rate performance and good cycling stability. The optimum design of the core-shell nanostructure shows promise for the synthesis of a variety of high-performance electrode materials.Silicon has a large specific capacity which is an order of magnitude beyond that of conventional graphite, making it a promising anode material for lithium ion batteries. However, the large volume changes (~300%) during cycling caused material pulverization and instability of the solid-electrolyte interphase resulting in poor cyclability which prevented its commercial application. Here, we have prepared a novel one-dimensional core-shell nanostructure in which the Si nanoparticles have been confined within hollow carbon nanofibres. Such a unique nanostructure exhibits high conductivity and facile ion transport, and the uniform pores within the particles which are generated during magnesiothermic reduction can serve as a buffer zone to accommodate the large volume changes of Si during electrochemical lithiation. Owing to these advantages, the composite shows high rate performance and good cycling stability. The optimum design of

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

    PubMed

    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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27033096

  4. Anodic-stripping voltammetric immunoassay for ultrasensitive detection of low-abundance proteins using quantum dot aggregated hollow microspheres.

    PubMed

    Zhang, Bing; Tang, Dianping; Goryacheva, Irina Yu; Niessner, Reinhard; Knopp, Dietmar

    2013-02-11

    A new anodic-stripping voltammetric immunoassay protocol for detection of IgG1, as a model protein, was designed by using CdS quantum dot (QD) layer-by-layer assembled hollow microspheres (QDHMS) as molecular tags. Initially, monoclonal anti-human IgG1 specific antibodies were anchored on amorphous magnetic beads preferably selective to capture F(ab) of IgG1 analyte from the sample. For detection, monoclonal anti-human IgG1 (F(c)-specific) antibodies were covalently coupled to the synthesized QDHMS. In a sandwich-type immunoassay format, subsequent anodic-stripping voltammetric detection of cadmium released under acidic conditions from the coupled QDs was conducted at an in situ prepared mercury film electrode. The immunoassay combines highly efficient magnetic separation with signal amplification by the multilayered QD labels. The dynamic concentration range spanned from 1.0 fg mL(-1) to 1.0 μg mL(-1) of IgG1 with a detection limit of 0.1 fg mL(-1). The electrochemical immunoassay showed good reproducibility, selectivity, and stability. The analysis of clinical serum specimens revealed good accordance with the results obtained by an enzyme-linked immunosorbent assay method. The new immunoassay is promising for enzyme-free, and cost-effective analysis of low-abundance biomarkers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Flexible carbon cloth electrode modified by hollow core-mesoporous shell carbon as a novel efficient bio-anode for biofuel cell.

    PubMed

    Olyveira, Gabriel M; Kim, Jung Ho; Martins, Marccus V A; Iost, Rodrigo M; Chaudhari, Kiran N; Yu, Jong-Sung; Crespilho, Frank N

    2012-01-01

    A new approach is described to produce an efficient electrode material for biofuel cells using flexible carbon cloth (FCC) and hollow core-mesoporous shell carbon (HCMSC) nanospheres as bio-anode materials. The bio-electrochemical activity of glucose oxidase (GOx) enzyme adsorbed on this bio-anode was evaluated, with the maximum anodic current density varying from 80 microA cm(-2) to 180 microA cm-2 for glucose concentrations up to 5.0 mmol L(-1) for the FCC modified electrode with HCMSCs. The open circuit cell voltage was E(0) = 380 mV, and the catalytic electro-oxidation current of glucose reached 0.1 mA cm(-2) at 0.0 V versus Ag/AgCl. This new system employing HCMSC-based FCC is promising toward novel bio-anodes for biofuel cells using glucose as a fuel.

  6. Promotional role of B2O3 in enhancing hollow SnO2 anode performance for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Ruiqing; Li, Deyu; Tian, Dong; Xia, Guofeng; Wang, Chen; Xiao, Ning; Li, Ning; Mack, Nathan H.; Li, Qing; Wu, Gang

    2014-04-01

    A composite anode consisting of hollow SnO2 microspheres covered by glass-like B2O3 layers was prepared via a combined hydrothermal-impregnation method, which results in much improved electrochemical performance in lithium ion batteries, relative to pristine SnO2 anodes. The cycling and rate capabilities of the SnO2-B2O3 composite anodes were investigated as a function of B2O3 content. The balance between increased electron-acceptor effect and compromised electronic conductivity due to addition of B2O3 is maximized around 20 wt% B2O3 loading. The best performing SnO2-B2O3 composite anode exhibits a specific capacity of 622.7 mAh g-1 up to 160 cycles, and is able to maintain a capacity above 528.6 mAh g-1 at rate of 5C. These enhanced performance characteristics are attributed to the unique composite structures consisting of the hollow SnO2 cores and the B2O3 buffer layers, which likely are beneficial for reducing the overall volume changes. Importantly, the decreased charge transfer resistance and increased Li+ diffusion coefficient, resulting from B2O3 coating, lead to overall improvement of rate performance for the composite anodes. Such-fabricated composite structures are stable during the Li+ insertion/extraction, thereby promoting cycling stability.

  7. Kirkendall-effect-based growth of dendrite-shaped CuO hollow micro/nanostructures for lithium-ion battery anodes

    SciTech Connect

    Hu Yingying; Huang Xintang; Wang Kai; Liu Jinping; Jiang Jian; Ding Ruimin; Ji Xiaoxu; Li Xin

    2010-03-15

    Three-dimensional (3D) dendrite-shaped CuO hollow micro/nanostructures have been prepared via a Kirkendall-effect-based approach for the first time and have been demonstrated as a high-performance anode material for lithium-ion batteries. The as-prepared hollow structures were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and electrochemical properties. A CuO hollow structure composed of nanocubes outside and a dense film inside was selected as a typical example of the optimized design; it exhibited significantly improved cyclability at a current rate of 0.5 C, with the average Coulombic efficiency of {approx}97.0% and 57.9% retention of the discharge capacity of the second cycle after 50 cycles. The correlation between the structure features of the hollow CuO and their electrochemical behavior was discussed in detail. Smaller size of primary structure and larger internal space of electrode materials are crucial to better electrochemical performance. This work represents that Kirkendall effect is a promising method to fabricate excellent hollow electrode materials for Li-ion batteries. - Graphical abstract: SEM images of 3D dendrite-shaped CuO hollow micro/nanostructures prepared via a Kirkendall-effect-based approach have been shown. The as-prepared CuO electrode exhibited significantly improved cyclability for Li-ion batteries.

  8. 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.

    PubMed

    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%.

  9. Reconstruction of Mini-Hollow Polyhedron Mn2O3 Derived from MOFs as a High-Performance Lithium Anode Material.

    PubMed

    Cao, Kangzhe; Jiao, Lifang; Xu, Hang; Liu, Huiqiao; Kang, Hongyan; Zhao, Yan; Liu, Yongchang; Wang, Yijing; Yuan, Huatang

    2016-03-01

    A mini-hollow polyhedron Mn2O3is used as the anode material for lithium-ion batteries. Benefiting from the small interior cavity and intrinsic nanosize effect, a stable reconstructed hierarchical nanostructure is formed. It has excellent energy storage properties, exhibiting a capacity of 760 mAh g(-1) at 2 A g(-1) after 1000 cycles. This finding offers a new perspective for the design of electrodes with large energy storage.

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

    PubMed

    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.

  11. Ultrafine Sn nanoparticles embedded in shell of N-doped hollow carbon spheres as high rate anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Dou, Peng; Cao, Zhenzhen; Wang, Chao; Zheng, Jiao; Xu, Xinhua

    2017-05-01

    A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn4+-MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn4+-MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g-1 at a current density of 0.2 A g-1 after 250 cycles and a reversible capacity of 221 mA h g-1 even at a much higher current density of 10 A g-1, which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact.

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

    PubMed

    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

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

    PubMed

    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

    2017-03-08

    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.

  14. Three-dimensional hollow-structured binary oxide particles as an advanced anode material for high-rate and long cycle life lithium-ion batteries

    DOE PAGES

    Wang, Deli; Wang, Jie; He, Huan; ...

    2015-12-30

    Transition metal oxides are among the most promising anode candidates for next-generation lithium-ion batteries for their high theoretical capacity. However, the large volume expansion and low lithium ion diffusivity leading to a poor charging/discharging performance. In this study, we developed a surfactant and template-free strategy for the synthesis of a composite of CoxFe3–xO4 hollow spheres supported by carbon nanotubes via an impregnation–reduction–oxidation process. The synergy of the composite, as well as the hollow structures in the electrode materials, not only facilitate Li ion and electron transport, but also accommodate large volume expansion. Using state-of-the-art electron tomography, we directly visualize themore » particles in 3-D, where the voids in the hollow structures serve to buffer the volume expansion of the material. These improvements result in a high reversible capacity as well as an outstanding rate performance for lithium-ion battery applications. As a result, this study sheds light on large-scale production of hollow structured metal oxides for commercial applications in energy storage and conversion.« less

  15. Three-dimensional hollow-structured binary oxide particles as an advanced anode material for high-rate and long cycle life lithium-ion batteries

    SciTech Connect

    Wang, Deli; Wang, Jie; He, Huan; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wu, Zexing; Liu, Hongfang

    2015-12-30

    Transition metal oxides are among the most promising anode candidates for next-generation lithium-ion batteries for their high theoretical capacity. However, the large volume expansion and low lithium ion diffusivity leading to a poor charging/discharging performance. In this study, we developed a surfactant and template-free strategy for the synthesis of a composite of CoxFe3–xO4 hollow spheres supported by carbon nanotubes via an impregnation–reduction–oxidation process. The synergy of the composite, as well as the hollow structures in the electrode materials, not only facilitate Li ion and electron transport, but also accommodate large volume expansion. Using state-of-the-art electron tomography, we directly visualize the particles in 3-D, where the voids in the hollow structures serve to buffer the volume expansion of the material. These improvements result in a high reversible capacity as well as an outstanding rate performance for lithium-ion battery applications. As a result, this study sheds light on large-scale production of hollow structured metal oxides for commercial applications in energy storage and conversion.

  16. Multishelled Nix Co3-x O4 Hollow Microspheres Derived from Bimetal-Organic Frameworks as Anode Materials for High-Performance Lithium-Ion Batteries.

    PubMed

    Wu, Lan-Lan; Wang, Zhuo; Long, Yan; Li, Jian; Liu, Yu; Wang, Qi-Shun; Wang, Xiao; Song, Shu-Yan; Liu, Xiaogang; Zhang, Hong-Jie

    2017-05-01

    Metal-organic frameworks (MOFs) featuring versatile topological architectures are considered to be efficient self-sacrificial templates to achieve mesoporous nanostructured materials. A facile and cost-efficient strategy is developed to scalably fabricate binary metal oxides with complex hollow interior structures and tunable compositions. Bimetal-organic frameworks of Ni-Co-BTC solid microspheres with diverse Ni/Co ratios are readily prepared by solvothermal method to induce the Ni x Co3-x O4 multishelled hollow microspheres through a morphology-inherited annealing treatment. The obtained mixed metal oxides are demonstrated to be composed of nanometer-sized subunits in the shells and large void spaces left between adjacent shells. When evaluated as anode materials for lithium-ion batteries, Ni x Co3-x O4 -0.1 multishelled hollow microspheres deliver a high reversible capacity of 1109.8 mAh g(-1) after 100 cycles at a current density of 100 mA g(-1) with an excellent high-rate capability. Appropriate capacities of 832 and 673 mAh g(-1) could also be retained after 300 cycles at large currents of 1 and 2 A g(-1) , respectively. These prominent electrochemical properties raise a concept of synthesizing MOFs-derived mixed metal oxides with multishelled hollow structures for progressive lithium-ion batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Modelling of tokamak glow discharge cleaning I: physical principles

    NASA Astrophysics Data System (ADS)

    Hagelaar, G. J. M.; Kogut, D.; Douai, D.; Pitts, R. A.

    2015-02-01

    Glow discharge cleaning (GDC) is a common technique for the conditioning of tokamak vessel walls in order to improve plasma performance and will be one of the primary conditioning techniques in ITER. The GDC discharge is a dc low-temperature plasma discharge, operated in the absence of the toroidal magnetic field, between one or more anodes inserted into the vessel, and the entire vessel wall serving as a cathode. This paper presents a self-consistent 2D model of the GDC discharge with the aim of improving fundamental understanding and predicting the wall ion current density distribution in ITER. The model combines a standard fluid model of the quasineutral plasma bulk with non-standard fluid equations for the fast electrons accelerated by the cathode sheath, based on transport coefficients and rate coefficients deduced from a Monte Carlo simulation. Examples of model results are shown in order to illustrate the general principles of the GDC discharge and the influence of the model input parameters. An important insight gained from this work is that the GDC discharge operates basically as a hollow-cathode discharge: the plasma is sustained mainly by ionization by secondary electrons emitted from the cathode, accelerated ballistically through a thin cathode sheath, penetrating the plasma as a fast electron beam, and trapped by the cathode fall surrounding the plasma on all sides. The electric field distribution inside the plasma, which determines the ion flux distribution on the vessel walls, is controlled by low-energy plasma bulk electrons. The relatively small surface area of the anode leads to the formation of an anode glow affecting the plasma uniformity. Comparisons with experimental data and predictions for ITER are presented in a companion paper.

  18. Bowl-like SnO2 @carbon hollow particles as an advanced anode material for lithium-ion batteries.

    PubMed

    Liang, Jin; Yu, Xin-Yao; Zhou, Han; Wu, Hao Bin; Ding, Shujiang; Lou, Xiong Wen David

    2014-11-17

    Despite the great advantages of hollow structures as electrodes for lithium-ion batteries, one apparent common drawback which is often criticized is their compromised volumetric energy density due to the introduced hollow interior. Here, we design and synthesize bowl-like SnO2 @carbon hollow particles to reduce the excessive hollow interior space while retaining the general advantages of hollow structures. As a result, the tap density can be increased about 30 %. The as-prepared bowl-like SnO2 @carbon hollow particles with conformal carbon support exhibit excellent lithium storage properties in terms of high capacity, stable cyclability and excellent rate capability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Surface binding of polypyrrole on porous silicon hollow nanospheres for Li-ion battery anodes with high structure stability.

    PubMed

    Du, Fei-Hu; Li, Bo; Fu, Wei; Xiong, Yi-Jun; Wang, Kai-Xue; Chen, Jie-Sheng

    2014-09-17

    Uniform porous silicon hollow nano-spheres are prepared without any sacrificial templates through a magnesio-thermic reduction of mesoporous silica hollow nanospheres and surface modified by the following in situ chemical polymerization of polypyrrole. The porous hollow structure and polypyrrole coating contribute significantly to the excellent structure stability and high electrochemical performance of the nanocomposite. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Electrostatic/magnetic ion acceleration through a slowly diverging magnetic nozzle between a ring anode and an on-axis hollow cathode

    NASA Astrophysics Data System (ADS)

    Sasoh, A.; Mizutani, K.; Iwakawa, A.

    2017-06-01

    Ion acceleration through a slowly diverging magnetic nozzle between a ring anode and a hollow cathode set on the axis of symmetry has been realized. Xenon was supplied as the propellant gas from an annular slit along the inner surface of the ring anode so that it was ionized near the anode, and the applied electric potential was efficiently transformed to an ion kinetic energy. As an electrostatic thruster, within the examined operation conditions, the thrust, F, almost scaled with the propellant mass flow rate; the discharge current, Jd, increased with the discharge voltage, Vd. An important characteristic was that the thrust also exhibited electromagnetic acceleration performance, i.e., the so-called "swirl acceleration," in which F ≅JdB Ra /√{2 }, where B and Ra were a magnetic field and an anode inner radius, respectively. Such a unique thruster performance combining both electrostatic and electromagnetic accelerations is expected to be useful as another option for in-space electric propulsion in its broad functional diversity.

  1. Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries.

    PubMed

    Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

    2015-02-28

    We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo(6+). The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g(-1) after 60 cycles at a current density of 100 mA g(-1), about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g(-1) after 60 cycles, it could still retain a stable specific capacity of 530 mA h g(-1), exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li(+) diffusion rate during the charge-discharge process.

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

    NASA Astrophysics Data System (ADS)

    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).

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2014-01-07

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28418001

  7. Facile synthesis and electrochemical performances of hollow graphene spheres as anode material for lithium-ion batteries

    PubMed Central

    2014-01-01

    The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H2(5%). The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g-1 at a current density of 50 mAh g-1. Even at a high current density of 500 mAh g-1, the reversible specific capacity remained at 502 mAh g-1. After 60 cycles, the reversible capacity was still kept at 652 mAh g-1 at the current density of 50 mAh g-1. These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets. PACS 81.05.ue; 61.48.Gh; 72.80.Vp PMID:25114657

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

    PubMed

    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.

  9. Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

    NASA Astrophysics Data System (ADS)

    Li, Tao; Wu, Zhentao; Li, K.

    2015-01-01

    In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

  10. Three-dimensional tin dioxide/carbon composite constructed by hollow nanospheres with quasi-sandwich structures as improved anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Tian, Qinghua; Tian, Yang; Zhang, Zhengxi; Yang, Li; Hirano, Shin-ichi

    2016-02-01

    Tin dioxide (SnO2)-based materials have been considered to be promisingly alternative advanced anode materials for lithium-ion batteries and thus attracted wide attention. So far, the research focus of SnO2-based anode materials is to search and develop effective strategies for overcoming the obstacles, such as rapid capacity fading and poor rate capability, which seriously impede the practical application of SnO2-based electrodes. Herein, we have successfully combined nanoscale SnO2 with 3-dimensional carbon (C) conductivity framework to form a 3-dimensional unparalleled SnO2/C composite constructed by closely interconnected hollow nanospheres with quasi-sandwich structures. When evaluated as anode materials for lithium-ion batteries, the as-prepared SnO2/C composite exhibits improved cycling performance and high rate capability, delivering a high capacity of 576.6 mAh g-1 at 200 mA g-1 even after 500 cycles, and a capacity of 411.7 mAh g-1 even at 5 A g-1 during rate test. The unparalleled 3-dimensional architecture should be responsible for the good electrochemical performance.

  11. Hollow core-shell structured Si/C nanocomposites as high-performance anode materials for lithium-ion batteries.

    PubMed

    Tao, Huachao; Fan, Li-Zhen; Song, Wei-Li; Wu, Mao; He, Xinbo; Qu, Xuanhui

    2014-03-21

    Hollow core-shell structured Si/C nanocomposites were prepared to adapt for the large volume change during a charge-discharge process. The Si nanoparticles were coated with a SiO2 layer and then a carbon layer, followed by etching the interface SiO2 layer with HF to obtain hollow core-shell structured Si/C nanocomposites. The Si nanoparticles are well encapsulated in a carbon matrix with an internal void space between the Si core and the carbon shell. The hollow core-shell structured Si/C nanocomposites demonstrate a high specific capacity and excellent cycling stability, with capacity decay as small as 0.02% per cycle. The enhanced electrochemical performance can be attributed to the fact that the internal void space can accommodate the volume expansion of Si during lithiation, thus preserving the structural integrity of electrode materials, and the carbon shell can increase the electronic conductivity of the electrode.

  12. Porous Ni0.14Mn0.86O1.43 hollow microspheres as high-performing anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ma, Zhong; Yuan, Xianxia; Li, Lin; Ma, Zi-Feng; Zhang, Lei; Mai, Liqiang; Zhang, Jiujun

    2015-09-01

    A uniformly dispersed bi-component nanocompotise of transition metal oxide (Mn2O3)/mixed transition metal oxide (NiMn2O4) with a porous and hollow microspheric sructure has been successfully prepared with a facile method based on the complexation between Ni2+ and NH3. The obtained nanocomposite of 0.29 Mn2O3/0.14 NiMn2O4, expressed as Ni0.14Mn0.86O1.43, with nanometer-sized building blocks exhibits a high reversible capacity of 615 mA h g-1, which is about 90% of theoretical value at the current density of 800 mA h g-1, and long lifespan with retained capacities of 553 and 408 mA h g-1 after 150 cycles at 200 and 800 mA g-1, respectively, as an anode material for lithium-ion batteries.

  13. Core-shell structure of hierarchical quasi-hollow MoS2 microspheres encapsulated porous carbon as stable anode for Li-ion batteries.

    PubMed

    Wan, Zhongming; Shao, Jie; Yun, Jiaojiao; Zheng, Huiyuan; Gao, Tian; Shen, Ming; Qu, Qunting; Zheng, Honghe

    2014-12-10

    Monodisperse sulfonated polystyrene (SPS) microspheres are employed as both the template and carbon source to prepare MoS2 quasi-hollow microspheres-encapsulated porous carbon. The synthesis procedure involves the hydrothermal growth of MoS2 ultrathin nanosheets on the surface of SPS microspheres and subsequent annealing to remove SPS core. Incomplete decomposition of SPS during annealing due to the confining effect of MoS2 shells leaves residual porous carbon in the interior. When being evaluated as the anode materials of Li-ion batteries, the as-prepared C@MoS2 microspheres exhibit excellent cycling stability (95% of capacity retained after 100 cycles) and high rate behavior (560 mAh g(-1) at 5 A g(-1)).

  14. Preparation of fluorine-doped, carbon-encapsulated hollow Fe3O4 spheres as an efficient anode material for Li-ion batteries.

    PubMed

    Geng, Hongbo; Zhou, Qun; Pan, Yue; Gu, Hongwei; Zheng, Junwei

    2014-04-07

    Herein we report the design and synthesis of fluorine-doped, carbon-encapsulated hollow Fe3O4 spheres (h-Fe3O4@C/F) through mild heating of polyvinylidene fluoride (PVDF)-coated hollow Fe3O4 spheres. The spheres exhibit enhanced cyclic and rate performances. The as-prepared h-Fe3O4@C/F shows significantly improved electrochemical performance, with high reversible capacities of over 930 mA h g(-1) at a rate of 0.1 C after 70 cycles, 800 mA h g(-1) at a rate of 0.5 C after 120 cycles and 620 mA h g(-1) at a rate of 1 C after 200 cycles. This improved lithium storage performance is mainly ascribed to the encapsulation of the spheres with fluorine-doped carbon, which not only improves the reaction kinetics and stability of the solid electrolyte interface film but also prevents aggregation and drastic volume change of the Fe3O4 particles. These spheres thus represent a promising anode material in lithium-ion battery applications.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:26061390

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2015-06-10

    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

    DOEpatents

    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. Characterization of argon direct-current glow discharge with a longitudinal electric field applied at ambient air.

    PubMed

    Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

    2014-09-10

    A direct-current-driven plasma jet is developed by applying a longitudinal electric field on the flowing argon at ambient air. This plasma shows a torch shape with its cross-section increased from the anode to the cathode. Comparison with its counterparts indicates that the gas flow plays a key role in variation of the plasma structure and contributes much to enlarging the plasma volume. It is also found that the circular hollow metal base promotes generation of plasma with a high-power volume density in a limited space. The optical emission spectroscopy (OES) diagnosis indicates that the plasma comprises many reactive species, such as OH, O, excited N2, and Ar metastables. Examination of the rotational and vibrational temperature indicates that the plasma is under nonequilibrium condition and the excited species OH(A (2)Σ(+)), O((5)P), and N2(C (3)Πu) are partly generated by energy transfer from argon metastables. The spatially resolved OES of plasma reveals that the negative glow, Faraday dark space, and positive column are distributed across the gas gap. The absence of the anode glow is attributed to the fact that many electrons in the vicinity of the anode follow ions into the positive column due to the ambipolar diffusion in the flowing gas.

  1. Characterization of argon direct-current glow discharge with a longitudinal electric field applied at ambient air

    PubMed Central

    Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

    2014-01-01

    A direct-current-driven plasma jet is developed by applying a longitudinal electric field on the flowing argon at ambient air. This plasma shows a torch shape with its cross-section increased from the anode to the cathode. Comparison with its counterparts indicates that the gas flow plays a key role in variation of the plasma structure and contributes much to enlarging the plasma volume. It is also found that the circular hollow metal base promotes generation of plasma with a high-power volume density in a limited space. The optical emission spectroscopy (OES) diagnosis indicates that the plasma comprises many reactive species, such as OH, O, excited N2, and Ar metastables. Examination of the rotational and vibrational temperature indicates that the plasma is under nonequilibrium condition and the excited species OH(A 2Σ+), O(5P), and N2(C 3Πu) are partly generated by energy transfer from argon metastables. The spatially resolved OES of plasma reveals that the negative glow, Faraday dark space, and positive column are distributed across the gas gap. The absence of the anode glow is attributed to the fact that many electrons in the vicinity of the anode follow ions into the positive column due to the ambipolar diffusion in the flowing gas. PMID:25205176

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2013-01-01

    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. PMID:25685537

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

    PubMed

    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.

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

    PubMed

    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.

  6. Glow discharges with electrostatic confinement of fast electrons

    NASA Astrophysics Data System (ADS)

    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 < L, the cathode potential fall Uc is independent of gas pressure p. With increasing 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 < S*, the 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

  7. Mesoporous nitrogen-doped carbon hollow spheres as high-performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Huo, Kaifu; An, Weili; Fu, Jijiang; Gao, Biao; Wang, Lei; Peng, Xiang; Cheng, Gary J.; Chu, Paul K.

    2016-08-01

    Nitrogen-doped mesoporous carbon hollow spheres (N-MCHSs) were prepared using mesoporous silica hollow spheres as template and dopamine as carbon precursor. The N-MCHSs demonstrate high specific surface area and vegetable sponge-like mesoporous shell with interconnected ;carbon bridges;, facilitating continuous electron transport and Li ion diffusion, and making the whole structure more stable. The influence of N contents and N-bonding configuration on the Li storage of N-MCHSs is discussed. The N-MCHSs carbonized at 800 °C demonstrate high reversible capacity and excellent rate performance, delivering a capacity of 485 mAh g-1 at a current of 0.5 A g-1 after 1,100 cycles. Even up to 4.0 A g-1, a high capacity of 214 mAh g-1 can be remained. The high electrochemical performance of N-MCHSs can be ascribed to mesoporous carbon hollow spheres structure and high level pyridinic nitrogen doping.

  8. Hydrothermal Synthesis of Unique Hollow Hexagonal Prismatic Pencils of Co3 V2 O8 ⋅n H2 O: A New Anode Material for Lithium-Ion Batteries.

    PubMed

    Wu, Fangfang; Xiong, Shenglin; Qian, Yitai; Yu, Shu-Hong

    2015-09-07

    Hollow structures of transition-metal oxides, particularly mixed-metal oxides, could be promising for various applications such as lithium-ion batteries (LIBs). Compared to the synthesis of metal oxide hollow spheres by the template method, non-spherical metal oxide hollow hexagonal polyhedra have not been developed to date. Herein, we report the controlled hydrothermal synthesis of a new phase of Co3 V2 O8 ⋅n H2 O hollow hexagonal prismatic pencils (HHPPs), which is composed of uniform structural units. By varying the amount of NaOH in the presence of NH4 (+) and without any template or organic surfactant, the hexagonal prismatic pencils gradually transform from solid into hollow structures, with sizes varying from 5 to 20 μm. The structure of pencils can be preserved only in a limited range of the molar ratio of OH(-) /NH4 (+) . As a new anode material for LIBs, such hollow pencils exhibit impressive lithium storage properties with high capacity, good cycling stability, and superior rate capability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Graphene-encapsulated hollow Fe₃O₄ nanoparticle aggregates as a high-performance anode material for lithium ion batteries.

    PubMed

    Chen, Dongyun; Ji, Ge; Ma, Yue; Lee, Jim Yang; Lu, Jianmei

    2011-08-01

    Graphene-encapsulated ordered aggregates of Fe(3)O(4) nanoparticles with nearly spherical geometry and hollow interior were synthesized by a simple self-assembly process. The open interior structure adapts well to the volume change in repetitive Li(+) insertion and extraction reactions; and the encapsulating graphene connects the Fe(3)O(4) nanoparticles electrically. The structure and morphology of the graphene-Fe(3)O(4) composite were confirmed by X-ray diffraction, scanning electron microscopy, and high-resolution transmission microscopy. The electrochemical performance of the composite for reversible Li(+) storage was evaluated by cyclic voltammetry and constant current charging and discharging. The results showed a high and nearly unvarying specific capacity for 50 cycles. Furthermore, even after 90 cycles of charge and discharge at different current densities, about 92% of the initial capacity at 100 mA g(-1) was still recoverable, indicating excellent cycle stability. The graphene-Fe(3)O(4) composite is therefore a capable Li(+) host with high capacity that can be cycled at high rates with good cycle life. The unique combination of graphene encapsulation and a hollow porous structure definitely contributed to this versatile electrochemical performance.

  11. Influence of thin porous Al{sub 2}O{sub 3} layer on aluminum cathode to the H{sub a}lpha line shape in glow discharge

    SciTech Connect

    Steflekova, V.; Sisovic, N. M.; Konjevic, N.

    2009-06-01

    The results of the Balmer alfa line shape study in a plane cathode-hollow anode Grimm discharge with aluminum (Al) cathode covered with thin layer of porous Al{sub 2}O{sub 3} are presented. The comparison with same line profile recorded with pure Al cathode shows lack of excessive Doppler broadened line wings, which are always detected in glow discharge with metal cathode. The effect is explained by the lack of strong electric field in the cathode sheath region, which is missing in the presence of thin oxide layer in, so called, spray discharge.

  12. Ring laser gyroscope anode

    SciTech Connect

    Ljung, B.H.

    1981-03-17

    An anode for a ring laser gyroscope which provides improved current stability in the glow discharge path is disclosed. The anode of this invention permits operation at lower currents thereby allowing a reduction of heat dissipation in the ring laser gyroscope. The anode of one embodiment of this invention is characterized by a thumbtack appearance with a spherical end where the normal sharp end of the thumbtack would be located. The stem of the anode extends from the outside of the gyroscope structure to the interior of the structure such that the spherical end is substantially adjacent to the laser beam.

  13. Glow discharge detector

    DOEpatents

    Koo, Jackson C.; Yu, Conrad M.

    2002-01-01

    A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured.

  14. Anode spots acting as independent self-organized systems

    SciTech Connect

    Biborosch, L.; Toma, M.; Sanduloviciu, M.

    1995-12-31

    The time averaged current-voltage (I-V) characteristics between two anodes A and P of a glow discharge in helium were taken by means of a circuit containing a dc voltage supply U{sub 12} and a small load resistor R{sub 1} or only a variable load resistor R{sub v}. Here the current I{sub 1}, through the movable wire anode P (0, 1 mm in diameter and 2,5 mm in length) were measured versus their bias voltage U{sub 12} in respect to the grounded hollow anode A. Fig. 2 shows the profiles of the I-V characteristics obtained for different axial distances d{sub p} between A and P. Thus, we have introduced two new external parameters, namely the axial distance d{sub p} and the voltage bias U{sub 12} (or the load resistor R{sub v}) to control the occurrence and features of the coherent and well defined nearly spherical anode spots, formed in front of A or around the wire P, respectively.

  15. 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.

    PubMed

    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.

  16. Droplet shaped anode double layer and electron sheath formation in magnetically constricted anode

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Anode double layer and droplet shaped fireball are found in a magnetically constricted anode. The disc shaped anode is constricted using permanent magnets. The device has only one anode and vacuum chamber acts as cathode. Plasma is created through glow discharge by applying high voltage between the anode and the cathode. Large size droplet shaped glow is obtained near the anode and is shown to have a double layer structure. Discharge is operated in pressure range from 5 ×10-3 mbar to 5 ×10-2 mbar keeping discharge current between 1 and 10 mA . Typical plasma density obtained near anode is 1 ×1010 cm-3 . The profile of plasma potential clearly shows two distinct regions with potential difference of 15.6 V at the boundary of anode glow. The potential difference is close to the ionization potential of Argon gas, which is used during the experiment. This distinct region is visible as bright anode glow and dark "bulk plasma" fill the chamber. This indicates the presence of the double layer formation. The role of magnetic field is also discussed in the formation of the glow, its shape, and the plasma potential profile.

  17. In Situ Synthesis of MnS Hollow Microspheres on Reduced Graphene Oxide Sheets as High-Capacity and Long-Life Anodes for Li- and Na-Ion Batteries.

    PubMed

    Xu, Xijun; Ji, Shaomin; Gu, Mingzhe; Liu, Jun

    2015-09-23

    Uniform MnS hollow microspheres in situ crystallized on reduced graphene oxide (RGO) nanosheets via a facile hydrothermal method. The MnS/RGO composite material was used as the anode for Na-ion batteries for the first time and exhibited excellent cycling performance, superior specific capacity, and great cycle stability and rate capability for both Li- and Na-ion batteries. Compared with nonencapsulated pure MnS hollow microspheres, these MnS/RGO nanocomposites demonstrated excellent charge-discharge stability and long cycle life. Li-ion storage testing revealed that these MnS/RGO nanocomposites deliver high discharge-charge capacities of 640 mAh g(-1) at 1.0 A g(-1) after 400 cycles and 830 mAh g(-1) at 0.5 A g(-1) after 100 cycles. The MnS/RGO nanocomposites even retained a specific capacity of 308 mAh g(-1) at a current density of 0.1 A g(-1) after 125 cycles as the anode for Na-ion batteries. The outstanding electrochemical performance of the MnS/RGO composite attributed to the RGO nanosheets greatly improved the electronic conductivity and efficiently mitigated the stupendous volume expansion during the progress of charge and discharge.

  18. Stable glow discharge detector

    DOEpatents

    Koo, Jackson C.; Yu, Conrad M.

    2004-05-18

    A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) stable glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The stable glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma and a solid rod electrode. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured. The solid rod electrode provides greater stability and thus easier alignment.

  19. Submillimeter-Wave Observations of C_3N^- in AN Extended Negative Glow Discharge

    NASA Astrophysics Data System (ADS)

    Amano, T.

    2009-06-01

    Extended negative glow and hollow anode discharges are found to be good sources of negative ions, such as CN^-, C_2H^-, and C_4H^-, for observations of pure rotational lines in the submillimeter-wave region. Thaddeus et al. detected C_3N^- in a glow discharge in HC_3N diluted in Ar buffer gas, and its rotational lines up to 378 GHz (J=39-38) were measured. In the present investigation, this anion has been observed in an extended negative glow discharge in a gas mixture of C_2N_2 (˜ 2 mTorr) and C_2H_2 (˜ 3 mTorr) in Ar buffer gas of ˜ 15 mTorr at the cell wall temperature of 230 K. The optimum discharge current was 2-4 mA with 250 Gauss longitudinal magnetic field. The rotational lines of up to J=51-50 in the 495 GHz region have been measured, and the improved rotational and centrifugal distortion constants are obtained. In the discharge optimum for production of C_3N^-, neither CN nor C_3N was detected with a similar signal accumulation time used for observations of the anion. However, this reaction has been found to be an excellent source for HC_3N, and the dominant formation mechanism of C_3N^- is likely to be the dissociative electron attachment to HC_3N. The radiative association of C_3N with electrons seems to be unlikely at least for the extended negative glow discharge. Apparently HC_3N is synthesized by a fast neutral and neutral reaction (C_2{H}_2 + CN → HC_3{N} + {H} It is interesting to see that an isomer, HCCNC, is also detected in the discharge, although the number density of this species is found to be about two orders of magnitude smaller than that of HC_3N. Another isomer, HNCCC, has also been observed with much weaker signal intensity. This species might have been produced by the dissociative recombination reaction of HC_3NH^+ with electrons, although the detection of this cation has not been successful in this type of discharge. T. Amano, J. Chem. Phys., 129, 244305 (2008). P. Thaddeus et al.,Astrophys. J., 677,1132-1139 (2008) K. Graupner

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

    SciTech Connect

    Couëdel, L. Kumar, K. Kishor; Arnas, C.

    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.

  1. Nano electrochemical reactors of Fe2O3 nanoparticles embedded in shells of nitrogen-doped hollow carbon spheres as high-performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zheng, Fangcai; He, Mengni; Yang, Yang; Chen, Qianwang

    2015-02-01

    Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles embedded in nitrogen-doped hollow carbon sphere shells (Fe2O3@N-C) by the direct pyrolysis of Fe-based zeolitic imidazolate frameworks (Fe-ZIF) at 620 °C in air. As an anode material for LIBs, the capacity retained was 1573 mA h g-1 after 50 cycles at a current density of 0.1 C (1 C = 1000 mA g-1). Even undergoing the high-rate capability test twice, it can still deliver a remarkably reversible and stable capacity of 1142 mA h g-1 after 100 cycles at a current density of 1 C. The excellent electrochemical performance is attributed to the unique structure of ultrasmall Fe2O3 nanoparticles uniformly distributed in the shell of nitrogen-doped carbon spheres, which simultaneously solve the major problems of pulverization, facilitate rapid electrochemical kinetics, and effectively avoid the aggregation of Fe2O3 nanoparticles during de/lithiation. The novel method developed in this work for the synthesis of functional hybrid materials can be extended to the preparation of various MOFs-derived functional nanocomposites owing to the versatility of links and metal centers in MOFs.Iron oxides are extensively investigated as anode materials for lithium-ion batteries (LIBs) because of their large specific capacities. However, they undergo huge volume changes during cycling that result in anode pulverization and loss of electrical connectivity. As a result, the capacity retention of the iron oxide anodes is poor and should be improved for commercial applications. Herein, we report the preparation of ultrasmall Fe2O3 nanoparticles

  2. Filling the vacuum chamber of a technological system with homogeneous plasma using a stationary glow discharge

    SciTech Connect

    Metel, A. S. Grigoriev, S. N.; Melnik, Yu. A.; Panin, V. V.

    2009-12-15

    Experimental study of a glow discharge with electrostatic confinement of electrons is carried out in the vacuum chamber volume V {approx} 0.12 m{sup 3} of a technological system 'Bulat-6' in argon pressure range 0.005-5 Pa. The chamber is used as a hollow cathode of the discharge with the inner surface area S {approx} 1.5 m{sup 2}. It is equipped with two feedthroughs, which make it possible to immerse in the discharge plasma interchangeable anodes with surface area S{sub a} ranging from {approx}0.001 to {approx}0.1 m{sup 2}, as well as floating electrodes isolated from both the chamber and the anode. Dependences of the cathode fall U{sub c} = 0.4-3 kV on the pressure p at a constant discharge current in the range I = 0.2-2 A proved that aperture of the electron escape out of the electrostatic trap is equal to the sum S{sub o} = S{sub a} + S{sub f} of the anode surface S{sub a} and the floating electrode surface S{sub f}. The sum S{sub o} defines the lower limit p{sub o} of the pressure range, in which U{sub c} is independent of p. At p < p{sub o} the cathode fall U{sub c} grows up dramatically, when the pressure decreases, and the pressure p tends to the limit p{sup ex}, which is in fact the discharge extinction pressure. At p {approx} p{sup ex} electrons emitted by the cathode and the first generation of fast electrons produced in the cathode sheath spend almost all their energy up to 3 keV on heating the anode and the floating electrode up to 600-800{sup o}C and higher. In this case the gas in the chamber is being ionized by the next generations of electrons produced in the cathode sheath, their energy being one order of magnitude lower. When S{sub a} < (2m/M){sup 1/2}S, where m is the electron mass and M is the ion mass, the anode may be additionally heated by plasma electrons accelerated by the anode fall of potential U{sub a} up to 0.5 kV.

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

    NASA Astrophysics Data System (ADS)

    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

  4. Metal-Organic Framework-Derived NiSb Alloy Embedded in Carbon Hollow Spheres as Superior Lithium-Ion Battery Anodes.

    PubMed

    Yu, Litao; Liu, Jun; Xu, Xijun; Zhang, Liguo; Hu, Renzong; Liu, Jiangwen; Yang, Lichun; Zhu, Min

    2017-01-25

    The MOFs (metal-organic frameworks) have been extensively used for electrode materials due to their high surface area, permanent porosity, and hollow structure, but the role of antimony on the MOFs is unclear. In this work, we design the hollow spheres Ni-MOFs with SbCl3 to synthesize NiSb⊂CHSs (NiSb-embedded carbon hollow spheres) via simple annealing and galvanic replacement reactions. The NiSb⊂CHSs inherited the advantages of Ni-MOFs with hollow structure, high surface area, and permanent porosity, and the NiSb nanoparticles are coated by the formed carbon particles which could effectively solve the problem of vigorous volume changes during the Li(+) insertion/extraction process. The porous and network structure could well provide an extremely reduced pathway for fast Li(+) diffusion and electron transport and provide extra free space for alleviating the structural strain. The NiSb⊂CHSs with these features were used as Li-ion batteries for the first time and exhibited excellent cycling performance, high specific capacity, and great rate capability. When coupled with a nanostructure LiMn2O4 cathode, the NiSb⊂CHSs//LiMn2O4 full cell also characterized a high voltage operation of ≈3.5 V, high rate capability (210 mA h g(-1) at a current density of 2000 mA g(-1)), and high Coulombic efficiency of approximate 99%, meeting the requirement for the increasing demand for improved energy devices.

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

    PubMed

    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.

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

    SciTech Connect

    Ha Yan; Wang Huijuan; Wang Xiaofei

    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.

  7. Electron concentration distribution in a glow discharge in air flow

    NASA Astrophysics Data System (ADS)

    Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.

    1989-04-01

    Electron concentration distributions in a glow discharge in longitudinal and vortex air flows are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron concentration decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.

  8. Liquid-interfaced oscillating glow discharge detector for a flowing liquid system.

    PubMed

    Herring, C J; Piepmeier, E H

    1995-03-01

    A new liquid-interfaced oscillating glow discharge detector having a frequency and current response to femtomole and picomole quantities respectively of potassium nitrate and sucrose injected into an aqueous flowing eluent is presented. The glow discharge is formed in an argon atmosphere at ambient pressure between a platinum anode and a cathode consisting of an aqueous conducting solution. A detailed description of the appearance of the liquid-interfaced glow discharge at various electrode distances and the occurrence of high-frequency oscillations is given.

  9. NSTX Filament Preionization and Glow Discharge Cleaning Systems

    SciTech Connect

    Kugel, H. W.; Blanchard, W.; D'Amico, G.; Gernhardt, R.; Provost, T.

    1999-11-01

    Initial NSTX GDC experiments were performed with one moveable anode and a biased filament preionization system that allowed D2 and He Glow Discharge breakdowns at the actual operating pressure, voltage and current. The biased filament system was also operated continuously during ohmic operations, and used to reduce volt-sec consumption for February 1999 plasma discharges up to 280 KA. An upgraded system has been installed with 2 fixed wall anodes and 3 biased filaments; 2 on the mid-plane and one in the divertor region; all separately controllable remotely using a PLC system. Recent applications include assisting in preionization for 800 KA plasma discharges.

  10. Copper doped hollow structured manganese oxide mesocrystals with controlled phase structure and morphology as anode materials for lithium ion battery with improved electrochemical performance.

    PubMed

    Li, Qun; Yin, Longwei; Li, Zhaoqiang; Wang, Xuekun; Qi, Yongxin; Ma, Jingyun

    2013-11-13

    We develop a facile synthesis route to prepare Cu doped hollow structured manganese oxide mesocrystals with controlled phase structure and morphology using manganese carbonate as the reactant template. It is shown that Cu dopant is homogeneously distributed among the hollow manganese oxide microspherical samples, and it is embedded in the lattice of manganese oxide by substituting Mn(3+) in the presence of Cu(2+). The crystal structure of manganese oxide products can be modulated to bixbyite Mn2O3 and tetragonal Mn3O4 in the presence of annealing gas of air and nitrogen, respectively. The incorporation of Cu into Mn2O3 and Mn3O4 induces a great microstructure evolution from core-shell structure for pure Mn2O3 and Mn3O4 samples to hollow porous spherical Cu-doped Mn2O3 and Mn3O4 samples with a larger surface area, respectively. The Cu-doped hollow spherical Mn2O3 sample displays a higher specific capacity of 642 mAhg(-1) at a current density of 100 mA g(-1) after 100 cycles, which is about 1.78 times improvement compared to that of 361 mA h g(-1) for the pure Mn2O3 sample, displaying a Coulombic efficiency of up to 99.5%. The great enhancement of the electrochemical lithium storage performance can be attributed to the improvement of the electronic conductivity and lithium diffusivity of electrodes. The present results have verified the ability of Cu doping to improve electrochemical lithium storage performances of manganese oxides.

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

    PubMed

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

    2014-03-21

    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%).

  12. Positive Streamers and Glows in Air and Exhaust Gases

    NASA Astrophysics Data System (ADS)

    Morrow, R.

    1998-10-01

    Theoretical and experimental studies have been made of the effects of sub-microsecond voltage pulses on the plasma chemistry of real flue gases in a test cell. Chemical analysis shows that, for real flue gases, the pulsed system can remove up to 90 % of NO, and 30 % of SO_2, if a residence time of ~ 30s is used. We also find that (i) water vapour is essential to the removal of SO_2, but not for the removal of NO or NO_2; and (ii) that small quantities of N_2O are produced. The removal of SO2 is primarily due to reactions with OH radicals from water vapour, producing sulphuric acid, whereas nitrogen oxides are reduced by N atoms. When a positive voltage is abruptly applied to a point in air at atmospheric pressure, positive streamers are produced. A theory is presented for the development of the first such streamer by solving the continuity equations for electrons, positive ions and negative ions, including the effects of ionisation, attachment, recombination, electron diffusion, and photoionisation, simultaneously with Poisson's equation. With an applied voltage of 20 kV across a 50 mm gap, the streamer does not reach the cathode. When the voltage is sustained in the presence of free electrons, the electric field at the anode starts to recover until positive glow pulses develop at the anode. The presence of the positive glow corona precludes any further streamer formation; this limits the number of chemical reactions stimulated by the discharge because the positive glow is confined close to the anode. Thus, a limit is set for the voltage pulse width. A theory is also presented for the current and light pulses of positive glow corona from a point in air; results are obtained by solving the continuity equations, described above, in concentric sphere geometry. A series of ``saw--toothed'' current pulses of period ~ 1 μs are predicted with a dc current level. Accompanying the current peaks are discrete 30 ns wide pulses of light. It is found that if, in the presence

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

    NASA Astrophysics Data System (ADS)

    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

  14. Preparation of hollow microsphere@onion-like solid nanosphere MoS2 coated by a carbon shell as a stable anode for optimized lithium storage

    NASA Astrophysics Data System (ADS)

    Guo, Bangjun; Yu, Ke; Song, Haili; Li, Honglin; Tan, Yinghua; Fu, Hao; Li, Chao; Lei, Xiang; Zhu, Ziqiang

    2015-12-01

    A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries.A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05595d

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

    NASA Astrophysics Data System (ADS)

    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

  16. The theory of positive glow corona

    NASA Astrophysics Data System (ADS)

    Morrow, R.

    1997-11-01

    A theory for the current and light pulses of positive glow corona from a point in air is presented; this phenomenon was first observed as an apparently continuous glow by Michael Faraday. Results are obtained, in concentric sphere geometry, for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions, negative ions and metastable oxygen molecules, coupled with Poisson's equation. A series of `saw-toothed' current pulses of period about 0022-3727/30/22/008/img1 is predicted with a DC current level. Accompanying the current peaks are discrete pulses of light 30 ns wide. Successive `shells' of positive ions, from successive current pulses, carry 96% of the mean current. The mean current - voltage relationship has the classic square-law form. The seed electrons required for successive pulses are detached from negative ions by metastable oxygen molecules. Photo-ionization is crucial for the discharge at the anode and for the formation of negative ions throughout the gap. The pulse frequency varies with applied voltage and is found to be approximately proportional to the positive-ion mobility. The surface electric field at the central electrode remains close to Peek's onset field. The origin of onset streamers is explained and sub-microsecond voltage pulses are found to produce streamers. The results for concentric-cylinder electrodes are described briefly.

  17. Detection of surface glow related to spacecraft glow phenomenon

    SciTech Connect

    Langer, W.D.; Cohen, S.A.; Manos, D.M.; Motley, R.W.; Ono, M.; Paul, S.; Roberts, D.; Selberg, H.

    1986-02-01

    We have developed a high flux source of low energy neutral beams to study the spacecraft glow phenomena by using a biased limiter to neutralize plasma in ACT-1. Beams of nitrogen and nitrogen-oxygen mixtures with energies of 1 to 15 eV and fluxes greater than or equal to 10/sup 14//cm/sup 2//s were directed on target surfaces consisting of Z-302 and Z-306 paints. With the nitrogen beams we successfully detected a glow due to beam-surface interactions. In addition, we discovered a volume glow effect due to beam-gas interactions which may also play a role in spacecraft glow. 11 refs., 14 figs.

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

    NASA Astrophysics Data System (ADS)

    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

    NASA Astrophysics Data System (ADS)

    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. Dawn Blue Glow Artist Concept

    NASA Image and Video Library

    2015-03-02

    This artist concept shows NASA Dawn spacecraft arriving at the dwarf planet Ceres. Dawn travels through space using a technology called ion propulsion, with ions glowing with blue light are accelerated out of an engine, giving the spacecraft thrust.

  1. Reproducing continuous radio blackout using glow discharge plasma

    SciTech Connect

    Xie, Kai; Li, Xiaoping; Liu, Donglin; Shao, Mingxu; Zhang, Hanlu

    2013-10-15

    A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 10{sup 9} to 2.5 × 10{sup 11} cm{sup −3}. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.

  2. Hollow Nanobarrels of α-Fe2O3 on Reduced Graphene Oxide as High-Performance Anode for Lithium-Ion Batteries.

    PubMed

    Lee, Kang Soo; Park, Seyong; Lee, Wooyoung; Yoon, Young Soo

    2016-01-27

    Alpha-phase iron oxide nanoparticles (α-NPs), α-iron oxide hollow nanobarrels (α-HNBs), and α-HNBs on reduced graphene oxide (α-HNBs/RGO) for Li-ion batteries (LIBs) were synthesized by a time-efficient microwave method to improve the low electrical conductivity of iron oxide and exploit the porous structure of RGO, which prevents the volume expansion of α-Fe2O3 during the insertion/extraction. On the other hand, α-HNBs (∼200 nm in diameter, ∼360 nm in length) provide a short diffusion path for Li ions and accommodate the strain generated by the volume change. The α-HNBs/RGO hybrid structure was synthesized by a one-step microwave-assisted hydrothermal method to bond α-HNBs with RGO. The as-prepared α-HNBs/RGO electrode exhibited a superior reversible capacity of 1279 mA h g(-1) at 0.5 C after the first cycle; such a capacity was nearly recovered after numerous cycles (2nd to 100th cycle, 95%). The long-term cyclability of α-HNBs/RGO shows 478 mA h g(-1) after 1000 cycles. Moreover, the α-HNBs/RGO electrode shows a high rate capacity of 403 mA h g(-1) even at 10 C. The α-HNBs/RGO exhibited a better electrochemical performance that could be attributed to the absence of nanoparticle agglomeration and RGO restacking, which provided a buffer effect against the volume expansion, promoted electrical conductivity and high structural integrity.

  3. Characteristics of short dc glow microdischarges in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly

    2013-09-01

    The main reason that high pressure current-carrying plasmas tend to be unstable is various instability (primarily thermal) of the positive column (PC). So a promising approach is to use short (without PC) discharges that have growing voltage-current characteristic (VAC). These discharges are ignited near the minimum of the Paschen breakdown curve Lmin and it usually have a gap pL <10-20 cm Torr when a distinct PC is absent. In this report the most stable microdischarges were burning with a flat cathode and rounded (or thin rod) anode, which located to a distance less than Lmin when the microdischarge ``choose'' their length itself, so that to match the stable work near Lmin by changing their binding on the anode. For simulations we used 2D hybrid model. 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, in which the electric field is distributed no uniformly and plasma is nonlocal. Gas heating plays an important role in shaping the discharge profiles. Work supported by FZP and SPbSU.

  4. Low temperature aluminum reduction cell using hollow cathode

    DOEpatents

    Brown, Craig W.; Frizzle, Patrick B.

    2002-08-20

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. A plurality of non-consumable anodes are disposed substantially vertically in the electrolyte along with a plurality of monolithic hollow cathodes. Each cathode has a top and bottom and the cathodes are disposed vertically in the electrolyte and the anodes and the cathodes are arranged in alternating relationship. Each of the cathodes is comprised of a first side facing a first opposing anode and a second side facing a second opposing anode. The first and second sides are joined by ends to form a reservoir in the hollow cathode for collecting aluminum therein deposited at the cathode.

  5. Heaterless ignition of inert gas ion thruster hollow cathodes

    NASA Technical Reports Server (NTRS)

    Schatz, M. F.

    1985-01-01

    Heaterless inert gas ion thruster hollow cathodes were investigated with the aim of reducing ion thruster complexity and increasing ion thruster reliability. Cathodes heated by glow discharges are evaluated for power requirements, flowrate requirements, and life limiting mechanisms. An accelerated cyclic life test is presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Hollow Retroreflectors

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A hollow retroreflector is a mirror-like instrument that reflects light and other radiations back to the source. After developing a hollow retroreflector for NASA's Apollo-Soyuz mission, PLX, Inc. continued to expand the technology and develop a variety of retroreflector systems. The Lateral Transfer Hollow Retroreflector maintains precise separation, at any wavelength, of incoming and existing beams regardless of their orientation. It can be used as an instrument or as a component of an optical system. In the laboratory, it offers a new efficient means of beam positioning. In other applications, it connects laser resonators, aligns telescope mirrors and is useful in general boresighting and alignment.

  8. Remote control for anode-cathode adjustment

    DOEpatents

    Roose, Lars D.

    1991-01-01

    An apparatus for remotely adjusting the anode-cathode gap in a pulse power machine has an electric motor located within a hollow cathode inside the vacuum chamber of the pulse power machine. Input information for controlling the motor for adjusting the anode-cathode gap is fed into the apparatus using optical waveguides. The motor, controlled by the input information, drives a worm gear that moves a cathode tip. When the motor drives in one rotational direction, the cathode is moved toward the anode and the size of the anode-cathode gap is diminished. When the motor drives in the other direction, the cathode is moved away from the anode and the size of the anode-cathode gap is increased. The motor is powered by batteries housed in the hollow cathode. The batteries may be rechargeable, and they may be recharged by a photovoltaic cell in combination with an optical waveguide that receives recharging energy from outside the hollow cathode. Alternatively, the anode-cathode gap can be remotely adjusted by a manually-turned handle connected to mechanical linkage which is connected to a jack assembly. The jack assembly converts rotational motion of the handle and mechanical linkage to linear motion of the cathode moving toward or away from the anode.

  9. Second Workshop on Spacecraft Glow

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr. (Editor); Moorehead, T. W. (Editor)

    1985-01-01

    Various aspects of space glow were considered. Results of a workshop held on May 6 to 7, 1985, at the Space Science Laboratory of NASA/Marshall Space Flight Center, Huntsville, Alabama are presented. The topics of discussion are divided as follows: (1) in situ observations; (2) theoretical calculations; (3) laboratory measurements; and (4) future experiments.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Glow discharge initiation with electron gun assist

    NASA Astrophysics Data System (ADS)

    Holtrop, K. L.; Jackson, G. L.; Schaubel, K. M.; Kellman, A. G.

    1991-11-01

    Helium glow discharge conditioning is used before every discharge in the D3-D Tokamak to desorb hydrogen and low Z impurities from the graphite and Inconel plasma facing surfaces. However high gas pressure is required to initiate each glow discharge session and this requires frequent cycling of valves to protect pressure sensitive devices. To alleviate this mechanical fatigue an electron gun assisted glow system (EAG) is being installed on the D3-D vessel to lower the initiation pressure. Through the injection of electrons the initiation pressure of the helium glow discharge has been lowered by a factor of 70, bringing the initiation pressure within a factor of 2 of the minimum sustaining pressure of the glow discharge. This might also make possible pulsed glow conditioning which would allow a lower average pressure during glow conditioning reducing the heat load on proposed cryogenic pumping panels. Experimental results of the electron assist on He glow initiation and a scaling model for the electron gun assisted glow will be presented. The electron gun can also be used as a diagnostic. Without a glow discharge, the electron gun has been pulsed into the wall and desorbed gas measured by a Residual Gas Analyzer. We are attempting to correlate the desorbed gas with recycling or vessel cleanliness.

  12. Constricted glow discharge plasma source

    DOEpatents

    Anders, Andre; Anders, Simone; Dickinson, Michael; Rubin, Michael; Newman, Nathan

    2000-01-01

    A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.

  13. Spectral characteristics of Shuttle glow

    NASA Technical Reports Server (NTRS)

    Viereck, R. A.; Mende, S. B.; Murad, E.; Swenson, G. R.; Pike, C. P.; Culbertson, F. L.; Springer, R. C.

    1992-01-01

    The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand-held, intensified spectrograph operated by the astronauts from the aft-flight-deck of the Space Shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the Shuttle window was performed on orbit using earth-airglow OH Meinel bands. This analysis resulted in a correction of the Shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum.

  14. Common Gamma-ray Glows above Thunderclouds

    NASA Astrophysics Data System (ADS)

    Kelley, Nicole; Smith, David; Dwyer, Joseph; Hazelton, Bryna; Grefenstette, Brian; Lowell, Alex; Splitt, Michael; Lazarus, Steven; Rassoul, Hamid

    2013-04-01

    Gamma-ray glows are continuous, long duration gamma- and x-ray emission seen coming from thunderclouds. The Airborne for Energetic Lightning Emissions (ADELE) observed 12 gamma-ray glows during its summer 2009 flight campaign over the areas of Colorado and Florida in the United States. For these glows we shall present their spectra, relationship to lightning activity and how their duration and size changes as a function of distance. Gamma-ray glows follow the relativistic runaway electron avalanche (RREA) spectrum and have been previously measured from the ground and inside the cloud. ADELE measured most glows as it flew above the screening layer of the cloud. During the brightest glow on August 21, 2009, we can show that we are flying directly into a downward facing relativistic runaway avalanche, indicative of flying between the upper positive and negative screening layer of the cloud. In order to explain the brightness of this glow, RREA with an electric field approaching the limit for relativistic feedback must be occurring. Using all 12 glows, we show that lightning activity diminishes during the onset of the glow. Using this along with the fact that glows occur as the field approaches the level necessary for feedback, we attempt to distinguish between two possibilities: that glows are evidence that RREA with feedback, rather than lightning, is sometimes the primary channel for discharging the cloud, or else that the overall discharging is still controlled by lightning, with glows simply appearing during times when a subsidence of lightning allows the field to rise above the threshold for RREA.

  15. Glow Sticks: Spectra and Color Mixing

    NASA Astrophysics Data System (ADS)

    Birriel, Jennifer; Birriel, Ignacio

    2014-10-01

    Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature.1-3 A black light can be used to illuminate glow sticks that have not been cracked or those that are "dead" in order to demonstrate fluorescence in liquid chemicals.4 In this article, we present the use of glow sticks as an inexpensive demonstration of spectra and color addition.

  16. Spacecraft ram glow and surface temperature

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Llewellyn, E. J.

    1987-01-01

    Space shuttle glow intensity measurements show large differences when the data from different missions are compared. In particular, on the 41-G mission the space shuttle ram glow was observed to display an unusually low intensity. Subsequent investigation of this measurement and earlier measurements suggest that there was a significant difference in temperature of the glow producing ram surfaces. The highly insulating properties coupled with the high emissivity of the shuttle tile results in surfaces that cool quickly when exposed to deep space on the night side of the orbit. The increased glow intensity is consistent with the hypothesis that the glow is emitted from excited NO2. The excited NO2 is likely formed through three body recombination (OI + NO + M = NO2*) where ramming of OI interacts with weakly surface bound NO. The NO is formed from atmospheric OI and NI which is scavenged by the spacecraft moving through the atmosphere. It is postulated that the colder surfaces retain a thicker layer of NO thereby increasing the probability of the reaction. It has been found from the glow intensity/temperature data that the bond energy of the surface bound precursor, leading to the chemical recombination producing the glow, is approximately 0.14 eV. A thermal analysis of material samples of STS-8 was made and the postulated temperature change of individual material samples prior to the time of glow measurements above respective samples are consistent with the thermal effect on glow found for the orbiter surface.

  17. Hollow memories

    NASA Astrophysics Data System (ADS)

    2014-04-01

    A hollow-core optical fibre filled with warm caesium atoms can temporarily store the properties of photons. Michael Sprague from the University of Oxford, UK, explains to Nature Photonics how this optical memory could be a useful building block for fibre-based quantum optics.

  18. Anode power deposition in magnetoplasmadynamic thrusters

    NASA Technical Reports Server (NTRS)

    Gallimore, A. D.; Kelly, A. J.; Jahn, R. G.

    1993-01-01

    Results of anode heat-flux and anode fail measurements from a multimegawatt self-field quasi-steady magnetoplasmadynamic (MPD) thruster are presented. Measurements were obtained with argon and helium propellants for a variety of currents and mass flow rates. Anode heat flux was directly measured with thermocouples attached to the inner surface of a hollowed section. Anode falls were determined both from floating probes and through heat flux measurements. Comparison of data acquired through either method shows excellent agreement. Anode falls varied between 4-50 V with anode power fractions reaching 70 percent with helium at 150 kW, and 50 percent with argon at 1.9 MW. The anode fall was found to correlate well with electron Hall parameters calculated from triple Langmuir and magnetic probe data collected near the anode. Two possible explanations for this result are proposed: (1) the establishment of large electric fields at the anode to maintain current conduction across the strong magnetic fields; and (2) anomalous resistivity resulting from the onset of microturbulence in the plasma. To investigate the latter hypothesis, electric field, magnetic field, and current density profiles measured in the vicinity of the anode were incorporated into Ohm's law to estimate the electrical conductivity. Results of this analysis show a substantial deviation of the measured conductivity from that calculated with classical formulas. These results imply that anomalous effects are present in the plasma near the anode.

  19. Anode power deposition in magnetoplasmadynamic thrusters

    NASA Astrophysics Data System (ADS)

    Gallimore, A. D.; Kelly, A. J.; Jahn, R. G.

    1993-06-01

    Results of anode heat-flux and anode fail measurements from a multimegawatt self-field quasi-steady magnetoplasmadynamic (MPD) thruster are presented. Measurements were obtained with argon and helium propellants for a variety of currents and mass flow rates. Anode heat flux was directly measured with thermocouples attached to the inner surface of a hollowed section. Anode falls were determined both from floating probes and through heat flux measurements. Comparison of data acquired through either method shows excellent agreement. Anode falls varied between 4-50 V with anode power fractions reaching 70 percent with helium at 150 kW, and 50 percent with argon at 1.9 MW. The anode fall was found to correlate well with electron Hall parameters calculated from triple Langmuir and magnetic probe data collected near the anode. Two possible explanations for this result are proposed: (1) the establishment of large electric fields at the anode to maintain current conduction across the strong magnetic fields; and (2) anomalous resistivity resulting from the onset of microturbulence in the plasma. To investigate the latter hypothesis, electric field, magnetic field, and current density profiles measured in the vicinity of the anode were incorporated into Ohm's law to estimate the electrical conductivity. Results of this analysis show a substantial deviation of the measured conductivity from that calculated with classical formulas. These results imply that anomalous effects are present in the plasma near the anode.

  20. APEX reveals glowing stellar nurseries

    NASA Astrophysics Data System (ADS)

    2008-11-01

    Illustrating the power of submillimetre-wavelength astronomy, an APEX image reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars. Submillimetre light is the key to revealing some of the coldest material in the Universe, such as these cold, dense clouds. Glowing Stellar Nurseries ESO PR Photo 40/08 Glowing Stellar Nurseries The region, called RCW120, is about 4200 light years from Earth, towards the constellation of Scorpius. A hot, massive star in its centre is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission. As this ionised region expands into space, the associated shock wave sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. However, as the clouds are still very cold, with temperatures of around -250˚ Celsius, their faint heat glow can only be seen at submillimetre wavelengths. Submillimetre light is therefore vital in studying the earliest stages of the birth and life of stars. The submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope, located on the 5000 m high plateau of Chajnantor in the Chilean Atacama desert. Thanks to LABOCA's high sensitivity, astronomers were able to detect clumps of cold gas four times fainter than previously possible. Since the brightness of the clumps is a measure of their mass, this also means that astronomers can now study the formation of less massive stars than they could before. The plateau of Chajnantor is also where ESO, together with international partners, is building a next generation submillimetre telescope, ALMA

  1. Glow Sticks: Spectra and Color Mixing

    ERIC Educational Resources Information Center

    Birriel, Jennifer; Birriel, Ignacio

    2014-01-01

    Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature. A black light can be used to…

  2. Glow Sticks: Spectra and Color Mixing

    ERIC Educational Resources Information Center

    Birriel, Jennifer; Birriel, Ignacio

    2014-01-01

    Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature. A black light can be used to…

  3. Hollow cathodes for arcjet thrusters

    NASA Technical Reports Server (NTRS)

    Luebben, Craig R.; Wilbur, Paul J.

    1987-01-01

    In an attempt to prevent exterior spot emission, hollow cathode bodies and orifice plates were constructed from boron nitride which is an electrical insulator, but the orifice plates melted and/or eroded at high interelectrode pressures. The most suitable hollow cathodes tested included a refractory metal orifice plate in a boron nitride body, with the insert insulated electrically from the orifice plate. In addition, the hollow cathode interior was evacuated to assure a low pressure at the insert surface, thus promoting diffuse electron emission. At high interelectrode pressures, the electrons tended to flow through the orifice plate rather than through the orifice, which could result in overheating of the orifice plate. Using a carefully aligned centerline anode, electron flow through the orifice could be sustained at interelectrode pressures up to 500 torr - but the current flow path still occasionally jumped from the orifice to the orifice plate. Based on these tests, it appears that a hollow cathode would operate most effectively at pressures in the arcjet regime with a refractory, chemically stable, and electrically insulating cathode body and orifice plate.

  4. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, S.A.; Glish, G.L.

    1989-07-18

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.

  5. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, Scott A.; Glish, Gary L.

    1989-01-01

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above.

  6. Goodbye, Hollows

    NASA Image and Video Library

    2015-04-21

    As NASA MESSENGER enters its final days, we are getting our last looks at some of our favorite features. Hollows, discovered in MDIS images during the orbital phase of the mission, are always photogenic. Three small hollows can be spotted in this scene located to the northwest of the Caloris basin near Timgad Vallis, including one that is surrounded by low-reflectance material. Date acquired: April 14, 2015 Image Mission Elapsed Time (MET): 71304311 Image ID: 8326733 Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) Center Latitude: 59.1° Center Longitude: 116.2° E Resolution: 17.1 meters/pixel Scale: This scene is approximately 17 km (11 miles) across http://photojournal.jpl.nasa.gov/catalog/PIA19425

  7. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  8. Is the negative glow plasma of a direct current glow discharge negatively charged?

    SciTech Connect

    Bogdanov, E. A.; Saifutdinov, A. I.; Demidov, V. I.; Kudryavtsev, A. A.

    2015-02-15

    A classic problem in gas discharge physics is discussed: what is the sign of charge density in the negative glow region of a glow discharge? It is shown that traditional interpretations in text-books on gas discharge physics that states a negative charge of the negative glow plasma are based on analogies with a simple one-dimensional model of discharge. Because the real glow discharges with a positive column are always two-dimensional, the transversal (radial) term in divergence with the electric field can provide a non-monotonic axial profile of charge density in the plasma, while maintaining a positive sign. The numerical calculation of glow discharge is presented, showing a positive space charge in the negative glow under conditions, where a one-dimensional model of the discharge would predict a negative space charge.

  9. Nanosecond Glow and Spark Discharges in Ambient Air and in Water Vapor

    NASA Astrophysics Data System (ADS)

    Laux, Christophe; Rusterholtz, Diane; Sainct, Florent; Xu, Da; Lacoste, Deanna; Stancu, Gabi; Pai, David

    2013-09-01

    Nanosecond repetitively pulsed (NRP) discharges are one of the most energy efficient ways to produce active species in atmospheric pressure gases. In both air and water vapor, three discharge regimes can be obtained: 1) corona, with light emission just around the anode, 2) glow, corresponding to a diffuse nonequilibrium plasma, and 3) spark, characterized by higher temperatures and higher active species densities. The glow regime was initially obtained in air preheated at 2000 K. Based on a model defining the transition between glow and spark, we recently succeeded in obtaining a stable glow in ambient air at 300 K, using a judicious combination of electrode geometry, pulse duration, pulse frequency, and applied voltage. We will present these results and describe the characteristics of the discharge obtained in room air. The spark regime was also studied. NRP sparks induce ultrafast gas heating (about 1000 K in 20 ns) and high oxygen dissociation (up to 50% dissociation of O2) . This phenomenon can be explained by a two-step process involving the excitation of molecular nitrogen followed by exothermic dissociative quenching of molecular oxygen. The characteristics of NRP discharges in water vapor will also be discussed. This work is supported by the ANR PREPA program (grant number ANR-09-BLAN-0043).

  10. Simulation Study of an Extended Density DC Glow Toroidal Plasma Source

    SciTech Connect

    Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Benitez-Read, J. S.; Pacheco-Sotelo, J. O.; Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia A, R.; Barocio, S. R.

    2006-12-04

    Conventional wisdom assigns the DC glow discharge regime to plasma currents below {approx}500 mA values, beyond which the discharge falls into the anomalous glow and the turbulent arc regimes. However, we have found evidence that, during toroidal discharges, this barrier can be ostensibly extended up to 800 mA. Thus, a computer simulation has been applied to the evolution of the main electrical characteristics of such a glow discharge plasma in a toroidal vessel in order to design and construct a respective voltage/current controlled source. This should be able to generate a DC plasma in the glow regime with which currents in the range 10-3-100 A can be experimented and 109-1010 cm-3 plasma densities can be achieved to PIII optimization purposes. The plasma is modelled as a voltage-controlled current source able to be turned on whenever the breakdown voltage is reached across the gap between the anode and the vessel wall. The simulation outcome fits well our experimental measurements showing that the plasma current obeys power laws that are dependent on the power current and other control variables such as the gas pressure.

  11. Infrared spectral measurement of space shuttle glow

    SciTech Connect

    Ahmadijian, M.

    1992-01-01

    Infrared spectral measurements of the space shuttle glow were successfully conducted during the STS-39 space shuttle mission. Analysis indicates that NO, NO[sup +], OH, and CO are among the molecules associated with the infrared glow phenomenon. During orbiter thruster firings the glow intensities in the infrared are enhanced by factors of 10x to 100x with significant changes in spectral distribution. These measurements were obtained with the Spacecraft Kinetic Infrared Test (SKIRT) payload which included a cryogenic infrared circular variable filter (CVF) spectrometer (0.6 [mu]m to 5.4 [mu]) and a number of infrared, visible, and ultraviolet radiometers (0.2 [mu]m to 5.4 [mu]m and 9.9 [mu]m to 10.4 [mu]m). In addition, glow measurements were unsuccessfully attempted with the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) with its 2.5 [mu]m to 25 [mu]m Fourier transform interferometer. SKIRT CVF obtained over 14,000 spectra of quiescent shuttle glow, thruster enhanced shuttle glow, upper atmosphere airglow, aurora, orbiter environment, and deep space non-glow backgrounds during its eight day mission. The SKIRT radiometers operated almost continuously throughout the mission to provide a detailed history of the IR/VIS/UV optical environment associated with the operation of large spacecraft structures in low earth orbit. This dissertation will primarily address those measurements conducted by the SKIRT spectrometer as they relate to space shuttle glow in the infrared. The STS-39 Space Shuttle Discovery was launched from the NASA Kennedy Space Center on 28 April 1991 into a 57 degree inclination circular orbit at an altitude of 260 km.

  12. UV Sustained Glow Discharge Opening Switch.

    DTIC Science & Technology

    1985-06-01

    the program were to undertake a theoretical and experimental investigation into the physics of UV sustained glow discharge opening switches with high...experimental investigation to develop scaling rules for the UV -sustained glow discharge, particularly for, but not restricted to, opening switch ...time is likely due to light emission from the flashboard substrate surface . As described in section 4.3, this long UV decay time severly restricts switch

  13. Vehicle glow measurements on the space shuttle

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Swenson, G. R.

    1985-01-01

    From the combined data set of glow observations on shuttle flight STS-3, STS-4, STS-5, STS-8, STS-9, 41-E, and 41-G some of the properties of the shuttle glow are discussed. Comparison of the STS-3 and STS-5 (240 and 305 km altitude, respectively) photographs shows that the intensity of the glow is about a factor of 3.5 brighter on the low-altitude (STS-3) flight. In an experiment to observe the dependence of the intensity on the ram angle, the angle of incidence between the spacecraft surface normal and the velocity vector, the Orbiter was purposely rotated about the x axis on the STS-5 mission. For a relatively large angle between the velocity vector and the surface normal there is an appreciable glow, provided the surface is not shadowed by some other spacecraft structure. As the angle becomes less the glow intensifies. Material samples were also exposed in the ram direction during nightside orbits and the glow surrounding the samples was photographed.

  14. Ultrasonic nebulization atmospheric pressure glow discharge - Preliminary study

    NASA Astrophysics Data System (ADS)

    Greda, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-07-01

    Atmospheric pressure glow microdischarge (μAPGD) generated between a small-sized He nozzle jet anode and a flowing liquid cathode was coupled with ultrasonic nebulization (USN) for analytical optical emission spectrometry (OES). The spatial distributions of the emitted spectra from the novel coupled USN-μAPGD system and the conventional μAPGD system were compared. In the μAPGD, the maxima of the intensity distribution profiles of the atomic emission lines Ca, Cd, In, K, Li, Mg, Mn, Na and Sr were observed in the near cathode region, whereas, in the case of the USN-μAPGD, they were shifted towards the anode. In the novel system, the intensities of the analytical lines of the studied metals were boosted from several to 35 times. As compared to the conventional μAPGD-OES with the introduction of analytes through the sputtering and/or the electrospray-like nebulization of the flowing liquid cathode solution, the proposed method with the USN introduction of analytes in the form of a dry aerosol provides improved detectability of the studied metals. The detection limits of metals achieved with the USN-μAPGD-OES method were in the range from 0.08 μg L- 1 for Li to 52 μg L- 1 for Mn.

  15. Electrospun manganese-cobalt oxide hollow nanofibres synthesized via combustion reactions and their lithium storage performance.

    PubMed

    Hwang, Soo Min; Kim, So Yeun; Kim, Jae-Geun; Kim, Ki Jae; Lee, Jong-Won; Park, Min-Sik; Kim, Young-Jun; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-05-14

    Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries.

  16. Anodizing Process

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This anodizing process traces its origin to the 1960's when Reynolds Metals Company, under contract with Goddard Space Flight Center, developed a multipurpose anodizing electrolyte (MAE) process to produce a hard protective finish for spacecraft aluminum. MAE produces a high-density, abrasion-resistant film prior to the coloring step, in which the pores of the film are impregnated with a metallic form of salt. Tru-Color product applications include building fronts, railing, curtain walls, doors and windows.

  17. Computer Simulation of Intense Electron Beam Generation in a Hollow Cathode Diode.

    DTIC Science & Technology

    1980-09-05

    impedance diode.1 The experimental arrangement is depicted in Fig. 1. A simple carbon hollow cathode opposed a flat plate porous graphite anode...Availability Codeas B 1!Avail and/or OCT 2___isSeca V B COMPUTER SIMULATION OF INTENSE ELECTRON BEAM GENERATION IN A HOLLOW CATHODE DIODE Introduction...relatively easy to see. Figure 2 provides a scale drawing of the actual geometry of the diode modeled. The hollow -cathode projects into the

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Negative ion source with hollow cathode discharge plasma

    DOEpatents

    Hershcovitch, A.; Prelec, K.

    1980-12-12

    A negative ion source of the type where negative ions are formed by bombarding a low-work-function surface with positive ions and neutral particles from a plasma, wherein a highly ionized plasma is injected into an anode space containing the low-work-function surface is described. The plasma is formed by hollow cathode discharge and injected into the anode space along the magnetic field lines. Preferably, the negative ion source is of the magnetron type.

  20. Negative ion source with hollow cathode discharge plasma

    DOEpatents

    Hershcovitch, Ady; Prelec, Krsto

    1983-01-01

    A negative ion source of the type where negative ions are formed by bombarding a low-work-function surface with positive ions and neutral particles from a plasma, wherein a highly ionized plasma is injected into an anode space containing the low-work-function surface. The plasma is formed by hollow cathode discharge and injected into the anode space along the magnetic field lines. Preferably, the negative ion source is of the magnetron type.

  1. Sound wave propagation through glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Stepaniuk, Vadim P.

    This work investigates the use of glow discharge plasma for acoustic wave manipulation. The broader goal is the suppression of aerodynamic noise using atmospheric glow discharge plasma as a sound barrier. Part of the effort was devoted to the development of a system for the generation of a large volume stable DC glow discharge in air both at atmospheric and at reduced pressures. The single tone sound wave propagation through the plasma was systematically studied. Attenuation of the acoustic wave passing through the glow discharge was measured for a range of experimental conditions including different discharge currents, electrode configurations, air pressures and sound frequencies including audible sound and ultrasound. Sound attenuation by glow discharge plasma as high as -28 dB was recorded in the experiments. Two types of possible mechanisms were considered that can potentially cause the observed sound attenuation. One is a global mechanism and the other is a local mechanism. The global mechanism considered is based on the reflection and refraction of acoustic wave due to the gas temperature gradients that form around the plasma. The local mechanism, on the other hand, is essentially the interaction of the acoustic wave with the plasma as it propagates inside the discharge and it can be viewed as a feedback system. Detailed temperature measurements, using laser-induced Rayleigh scattering technique, were carried out in the glow discharge plasma in order to evaluate the role of global mechanism in the observed attenuation. These measurements were made for a range of conditions in the atmospheric glow discharge. Theoretical analysis of the sound attenuation was carried out to identify the physical mechanism for the observed sound attenuation by plasma. It was demonstrated that the global mechanism is the dominant mechanism of sound attenuation. As a result of this study, the potentials and limitations of the plasma noise suppression technology were determined and

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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.

  5. Io Glowing in the Dark

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Volcanic hot spots and auroral emissions glow on the darkside of Jupiter's moon Io in the image at left. The image was taken by the camera onboard NASA's Galileo spacecraft on 29 June, 1996 UT while Io was in Jupiter's shadow. It is the best and highest-resolution image ever acquired of hot spots or auroral features on Io. The mosaic at right of 1979 Voyager images is shown with an identical scale and projection to identify the locations of the hot spots seen in the Galileo image. The grid marks are at 30 degree intervals of latitude and longitude. North is to the top.

    In the nighttime Galileo image, small red ovals and perhaps some small green areas are from volcanic hot spots with temperatures of more than about 700 kelvin (about 1000 degrees Fahrenheit). Greenish areas seen near the limb, or edge of the moon, are probably the result of auroral or airglow emissions of neutral oxygen or sulfur atoms in volcanic plumes and in Io's patchy atmosphere. The image was taken from a range of 1,035,000 kilometers (about 643,000 miles).

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  6. Io Glowing in the Dark

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Volcanic hot spots and auroral emissions glow on the darkside of Jupiter's moon Io in the image at left. The image was taken by the camera onboard NASA's Galileo spacecraft on 29 June, 1996 UT while Io was in Jupiter's shadow. It is the best and highest-resolution image ever acquired of hot spots or auroral features on Io. The mosaic at right of 1979 Voyager images is shown with an identical scale and projection to identify the locations of the hot spots seen in the Galileo image. The grid marks are at 30 degree intervals of latitude and longitude. North is to the top.

    In the nighttime Galileo image, small red ovals and perhaps some small green areas are from volcanic hot spots with temperatures of more than about 700 kelvin (about 1000 degrees Fahrenheit). Greenish areas seen near the limb, or edge of the moon, are probably the result of auroral or airglow emissions of neutral oxygen or sulfur atoms in volcanic plumes and in Io's patchy atmosphere. The image was taken from a range of 1,035,000 kilometers (about 643,000 miles).

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  7. Arcjet anode

    NASA Technical Reports Server (NTRS)

    Lichon, Paul G. (Inventor)

    1995-01-01

    There is disclosed an anode for an arcjet thruster which resists erosion during start-up on constriction during steady-state operation. The anode includes a converging upstream portion, a diverging downstream portion and a constricted portion disposed therebetween. In one embodiment of the invention, rails formed in the constricted portion accelerate the passage of an arc during start-up reducing erosion. In a second embodiment, a higher strength material resists bulging as a result of the thermal gradient within the nozzle.

  8. Laboratory investigation of visible shuttle glow mechanisms

    NASA Technical Reports Server (NTRS)

    Leone, A.; Swenson, G. R.; Caledonia, G. E.; Holtzclaw, K. W.

    1991-01-01

    Laboratory experiments designed to uncover mechanistic information about the spectral and spatial characteristics of shuttle glow were conducted. The luminescence was created when a pulse of O atoms traveling at orbital velocities was directed toward NO molecules previously adsorbed to aluminum, nickel, and Z306 Chemglaz (a common baffle black) coated surfaces held at various temperatures. Spectral and spatial measurements were made using a CCD imaging spectrometer. Corroborative spectral information was recorded in separate measurements using a scanning monochromator and gated photomultiplier arrangement. The e-folding distance at several temperatures was calculated from images of the surface glow using the photometrics image processing capability of the imaging spectrometer. The e-folding distance was not altered as a function of incoming O beam velocity. The results are presented and the observations provide direct evidence that the visible shuttle glow results from recombination of oxygen atoms and surface bound NO.

  9. A high resolution ultraviolet Shuttle glow spectrograph

    NASA Technical Reports Server (NTRS)

    Carruthers, George R.

    1993-01-01

    The High Resolution Shuttle Glow Spectrograph-B (HRSGS-B) is a small payload being developed by the Naval Research Laboratory. It is intended for study of shuttle surface glow in the 180-400 nm near- and middle-ultraviolet wavelength range, with a spectral resolution of 0.2 nm. It will search for, among other possible features, the band systems of excited NO which result from surface-catalyzed combination of N and O. It may also detect O2 Hertzberg bands and N2 Vegard-Kaplan bands resulting from surface recombination. This wavelength range also includes possible N2+ and OH emissions. The HRSGS-B will be housed in a Get Away Special canister, mounted in the shuttle orbiter payload bay, and will observe the glow on the tail of the orbiter.

  10. A Field of Hollows

    NASA Image and Video Library

    2015-04-01

    Mercury's hollows are among its most distinctive -- and unusual -- surface features. In this stunning view, we see a field of hollows in the western portion of the floor of Zeami impact basin. Hollows populate much of the rest of the basin's interior, with large concentrations several kilometers across occurring in the north and northeast parts of the floor. Individual hollows, however, can be as small as a couple of hundred meters in width. http://photojournal.jpl.nasa.gov/catalog/PIA19267

  11. A GLOWING POOL OF LIGHT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known to amateur astronomers in the southern hemisphere as the 'Eight-Burst' or the 'Southern Ring' Nebula. The name 'planetary nebula' refers only to the round shape that many of these objects show when examined through a small visual telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes. NGC 3132 is nearly half a light year in diameter, and at a distance of about 2000 light years is one of the nearer known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second. This image, captured by NASA's Hubble Space Telescope, clearly shows two stars near the center of the nebula, a bright white one, and an adjacent, fainter companion to its upper right. (A third, unrelated star lies near the edge of the nebula.) The faint partner is actually the star that has ejected the nebula. This star is now smaller than our own Sun, but extremely hot. The flood of ultraviolet radiation from its surface makes the surrounding gases glow through fluorescence. The brighter star is in an earlier stage of stellar evolution, but in the future it will probably eject its own planetary nebula. In the Heritage Team's rendition of the Hubble image, the colors were chosen to represent the temperature of the gases. Blue represents the hottest gas, which is confined to the inner region of the nebula. Red represents the coolest gas, at the outer edge. The Hubble image also reveals a host of filaments, including one long one that resembles a waistband, made out of dust particles which have condensed out of the expanding gases. The dust particles are rich in elements such as carbon. Eons from now, these particles may be incorporated into new stars and planets when they form from interstellar gas and dust. Our own Sun may eject a

  12. Saddle-field glow-discharge deposition of amorphous semiconductors

    SciTech Connect

    Gaspari, F.; Sidhu, L.S.; O`Leary, S.K.; Zukotynski, S.

    1996-12-31

    The authors present a dc saddle-field glow-discharge deposition procedure which combines the positive attributes of the conventional dc and rf glow-discharge techniques. Preliminary mass spectra analyses of both silane and methane glow-discharges demonstrates that ions constitute a significant fraction of the species reaching the film surface. Growth rate analyses suggest that ions play a significant role in the saddle-field glow-discharge deposition of amorphous semiconducting films.

  13. Lithium-fluoride flashover ion source cleaned with a glow discharge and irradiated with vacuum-ultraviolet radiation

    SciTech Connect

    Burns, E.J.T.; Woodworth, J.R.; Bieg, K.W.; Mehlhorn, T.A.; Stygar, W.A.; Sweeney, M.A.

    1988-01-01

    We have studied methods of varying the ion species generated by a lithium-fluoride overcoated anode in a 0.5-MV magnetically insulated ion diode. We found that cleaning the anode surface with a 13.6-MHz rf glow discharge or illuminating the anode with a pulsed soft x-ray, vacuum-ultraviolet (XUV) radiation source just before the accelerator pulse significantly altered the ion species of the ion beam produced by the diode. The glow-discharge plasma removed adsorbates (carbon, hydrogen, and oxygen) from the surface of the LiF flashover source. The ions seen were lithium and hydrogen. Unfortunately, the diode impedance with a lithium-fluoride anode was high and the ion efficiency was low; however, XUV irradiation of the surface dramatically lowered the impedance by desorbing neutrals from the ion source via photon-stimulated desorption. Current densities of ten times the Child--Langmuir space-charge limit were achieved under XUV irradiation. In particular, ion currents increased by over a factor of 3 when 12 mJ/cm/sup 2/ of XUV radiation was used. However, with XUV irradiation the largest fraction of ions were fluorine, oxygen, carbon, and hydrogen, not lithium.

  14. Physics and modeling of ITER glow discharge cleaning

    NASA Astrophysics Data System (ADS)

    Hagelaar, G. J. M.; Kogut, D.; Douai, D.; Pitts, R. A.

    2013-09-01

    Glow discharge cleaning (GDC) is a common technique for the conditioning of tokamak vessel walls in order to improve the tokamak plasma performance and reproducibility. The GDC discharge is a dc low-temperature plasma discharge, operated when the tokamak magnetic fields are off, between several anodes inserted into the vessel, and the vessel walls serving as a cathode. The plasma is sustained by fast electrons emitted from the walls by ion impact, accelerated through a thin cathode sheath up to nearly the discharge voltage, and then penetrating very far into the plasma. On the other hand, the electric potential in the plasma bulk, which determines the wall ion flux distribution, seems to be controlled by low-energy bulk electrons. This paper presents a self-consistent 2D model of the GDC discharge with the aim to improve fundamental understanding and predict the wall current density distribution as input to the ITER GDC system design. The model is based on a hybrid approach, combining a fluid model of the plasma bulk with a Monte-Carlo simulation of the fast electrons. Comparisons are shown with experimental results obtained on a small scale test stand. This work is funded by the IO-CEA/IRFM contract IA #14 ref 42-586 FRW 6-49.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2015-08-15

    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.

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

    SciTech Connect

    Xu, S. F.; Zhong, X. X.

    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.

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

    NASA Astrophysics Data System (ADS)

    Xu, S. F.; Zhong, X. X.

    2015-10-01

    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 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.

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

    PubMed

    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

  20. High Performance Hollow Projectiles

    DTIC Science & Technology

    Development of hollow projectiles was first advocated to achieve ’silent’ (low pressure signal) projectiles having higher performance. Although the...present effort concentrates on small arms (specifically 7.62 mm), the confirmed fundamental theory applies to all sizes of hollow projectiles. The...report can thus serve as a basis for (1) evaluating specific hollow projectile developments and (2) formulating programs to develop a wide spectrum of

  1. Hollow lensing duct

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

    2000-01-01

    A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

  2. Use of glow discharge in fluidized beds

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Wood, P. C.; Ballou, E. V.; Spitze, L. A. (Inventor)

    1981-01-01

    Static charges and agglomerization of particles in a fluidized bed systems are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing agents, i.e., moisture or conductive particle coatings, cannot be used. The technique is applied here to the disproportionation of calcium peroxide diperoxyhydrate to yield calcium superoxide, an exceptionally water and heat sensitive reaction.

  3. Glowing Gullies in Kaiser Crater Dunes

    NASA Image and Video Library

    2016-06-29

    The giant sand dunes in Kaiser Crater experience gully erosion of the steep slip faces every year in late winter as the sun warms these slopes and seasonal carbon dioxide frost sublimates (meaning it changes from a solid to gas). Some of these gullies produce a variety of colors that are highlighted on the west-facing (illuminated) slopes, where the gullies appear to be glowing in the winter light. http://photojournal.jpl.nasa.gov/catalog/PIA20736

  4. NASA CONNECT: 'Glow with the Flow'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    'Geometry and Algebra: Glow with the Flow' is the second of five programs in the 2000-2001 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology in grades 5-8. NASA CONNECT establishes teh 'connection' between the mathematics, science, and tehcnology concepts taught in the classroom and NASA research. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site adn register http://connect.larc.nasa.gov In 'Geometry and Algebra: Glow with the Flow', students will learn about the force of drag and how NASA engineers use models and glowing paints to see how air flows over vehicles in a wind tunnel. Students will also discover how the blended wing body(BWB), a concept super jumbo jet that resembles a flying wing, will affect air travelers of the future. Students will observe NASA engineers using geometry and algebra when they measure and design models to be tested in wind tunnels. By conducting classroom and on-line activities, students will make connections between NASA research and the mathematics, science and technology they learn in their classroom.

  5. Using glow stick chemistry for biological imaging.

    PubMed

    Tseng, Jen-Chieh; Bailey, Dyane; Tupper, Tanya; Kung, Andrew L

    2014-08-01

    This study describes an imaging strategy based on glow stick chemistry to non-invasively image oxidative stress and reactive oxygen species (ROS) production in living animals. Upon stimulation, phagocytes produce toxic levels of ROS to kill engulfed microorganisms. The mitochondrial respiratory chain continually generates low levels of superoxide (O2·(-)) that serve as a source for generation of downstream ROS, which function as regulatory signaling intermediaries. A ROS-reacting substrate, 2-methyl-6-[4-methoxyphenyl]-3,7-dihydroimidazo[1,2-a]pyrazin-3-one hydrochloride, was used as the chemical energy donor for generating energy transfer luminescence in phagosomes and mitochondria. Using targeted photoluminescent dyes with specific subcellular localization that serve as chemical energy recipients, our imaging data demonstrate proof-of-concept for using glow stick chemistry to visualize ROS production associated with phagocytosis and mitochondrial respiration in living mice. Glow stick imaging is a complementary hybrid of chemiluminescence and photoluminescence imaging, capable of generating red or far-red emission for deep tissue imaging.

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

    PubMed

    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.

  7. Comparative Study of Electric Field Measurement in Glow Discharges using Laser Optogalvanic Spectroscopy

    SciTech Connect

    Hussain, Shahid; Saleem, M.; Baig, M. A.

    2008-10-22

    The net electric field inside low-pressure glow discharges has been measured using laser optogalvanic spectroscopy of 1s2s {sup 1}S{sub 0}{yields}np{sup 1}P{sub 1} Rydberg series of atomic helium. Three different types of discharges, an inductively coupled RF discharge cell operating at 4 MHz, a homemade DC discharge cell and a commercial see-through hollow cathode lamp have been used for these studies. The Rydberg series terminates earlier in the high electric field discharge as compared to that in the low electric field discharge. The net electric field also produces shift and broadens the observed spectral lines especially in the high lying Rydberg transitions. The electric field has been determined from the series termination and also from the energy shift of the observed transitions.

  8. Effect of Anode Impurity on the Neutron Production in a Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Yousefi, H. R.; Masugata, K.

    2011-12-01

    In this study, neutron production characteristics were investigated by employing three different anode designs. Previously, Takao et al. in Plasma Sour Sci Technol 12:407, (2003) studied the effect of anode design on the production of impurity ions in a dense plasma focus (DPF) device. It was found that rod type anodes led to large quantities of impurity ions, resulting in an ion purity of only 25%. In contrast, in hollow type anodes the quantities of impurity ions is strongly reduced, resulting in an enhanced ion purity of 91%. These impurities in the DPF system originate partly from residual gas in the vacuum system, but also from vaporization of the anode, which produces metallic ions such as copper. In the present work, we extend previous investigations Takao et al. in Plasma Sour Sci Technol 12:407, (2003) of the effects of anode shape (A—long hollow, B—short hollow and C—rod type) on neutron production. Here we focus specifically on the effects of anode impurity on neutron production. It was found that in anode type C, the neutron intensity and neutron yield is lower than in type A or B.

  9. Particle beam sample introduction into glow discharge plasmas for speciation analysis

    NASA Astrophysics Data System (ADS)

    Brewer, Tim M.; Castro, Joaudimir; Marcus, R. Kenneth

    2006-02-01

    This paper reviews the use of the particle beam (PB) as a transport-type interface for the introduction of liquid samples into glow discharge (GD) plasmas. Emphasis is placed on the PB interface as a coupling for liquid chromatography (LC) with optical emission spectroscopy (OES) and mass spectrometry (MS) detection methods. Advantages and disadvantages of the particle beam sample introduction for LC-MS and LC-OES as well as a comparison with other interfaces (i.e. moving belt) are covered. Fundamental aspects of the particle beam such as solvent removal and analyte delivery are highlighted. Furthermore, the development of the particle beam interface is discussed regarding its potential for providing "comprehensive speciation" analysis of solution-phase samples. Specifically, the particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) technique provides information towards metal and non-metals determinations as well molecular species identification of organic compounds, organometallics, and small biomolecules via empirical formulae determinations. Particle beam-glow discharge mass spectrometry (PB/GDMS) also provides molecular species information through fragmentation pattern analysis of plasma-produced mass spectra that are similar in structure to electron impact (EI) sources. The evolving capabilities of the PB/GD couplings deliver analytical information that is not available from any other spectrochemical source. The technique has relevance to an incredible range of analytical applications and warrants further investigation by other researchers and instrument manufacturers.

  10. Instability of plasma plume of micro-hollow cathode discharge

    SciTech Connect

    Levko, D.; Bliokh, Y. P.; Gurovich, V. Tz.; Krasik, Ya. E.

    2015-11-15

    The micro-hollow cathode gas discharge driven by thermionic emission is studied using the two-dimensional particle-in-cell Monte Carlo collisions simulation. The electron current is extracted from the plasma plume penetrating into the keeper–anode space through a small keeper orifice from the cathode-keeper space. The results of simulations and a simplified analytical model showed that the plasma density and extracted current can exhibit deep modulation in the range of frequencies of tens of MHz. This modulation appears when the space-charge limited current between the plume boundary and the anode exceeds the plasma thermal electron current through the orifice.

  11. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  12. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  13. Resonance glow of the neutral interplanetary gas

    NASA Astrophysics Data System (ADS)

    Scherer, Horst

    2000-05-01

    The neutral hydrogen, embedded in the partially ionized local interstellar medium, can enter deeply into the heliosphere with the interstellar wind flow. While entering into the heliosphere it suffers from intense charge-exchange interactions with the solar wind protons. This charge-exchange leads to a fractional depletion of the interstellar hydrogen atoms inside the heliosphere and modulates their velocity and temperature distribution. The resulting thermodynamical conditions of the interstellar hydrogen inside the heliosphere are described by two kinetic density models. The first model by Wu & Judge specially takes into account the influence on hydrogen due to solar photo ionization and solar gravitation and leads to appropriate results in the solar vicinity. The second model by Osterbart & Fahr takes into account the plasma interaction effects near the solar wind shock region and near the heliopause. Hence, this model gives more realistic results for the hydrogen properties far away from the Sun. Besides these theoretical modelings of the interplanetary hydrogen, measurements of the interplanetary hydrogen HI-Lyman-Alpha resonance glow were performed and attempts have been made to deduce the relevant thermodynamical parameter of the neutral interstellar hydrogen by analyzing these glow data. Two radiation transport models will be discussed which are used to analyze the interplanetary hydrogen HI-Lyman-Alpha resonance glow data. First, the "optically thin" approximation which is used very often in the literature because of its simple numerical handling. Unfortunately, this model has a very limited region of validity. The second radiation transport model by Scherer & Fahr introduces the exact redistribution function which takes into account the local thermodynamical conditions of the scattering agent, like density, bulk velocity and temperature of the neutral interplanetary hydrogen. Also it takes into account the actually observed solar HI-Lyman-Alpha emission

  14. Stability of atmospheric pressure glow discharges

    NASA Astrophysics Data System (ADS)

    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

  15. Hollow cathode plasma coupling study, 1986

    NASA Technical Reports Server (NTRS)

    Wilbur, Paul J.

    1986-01-01

    The electron collection and emission characteristics of a simple hollow cathode contactor, an extended anode hollow cathode contactor supplied by JSC, and a ring cusp magnetic field contactor are presented and the effects of discharge power and argon or xenon expellant flowrate on these characteristics are examined. All of the contactors are shown to exhibit good electron emission performance over a wide range of discharge power and expellant type and flowrate. Good electron performance is shown to be more difficult to achieve. Results suggest that the extended anode and ring cusp contactors should perform satisfactorily to electron emission currents beyond 1000 mA and electron collection currents beyond 500 mA. All contactors performed better on xenon than argon. A general theory of plasma contactor operation in both the electron collection and electron emission modes, which describes the current-limiting effects of space-charge phenomena is given. This current-limiting and collecting phenomenon is shown to be a function of driving potential differences and emitting and collecting surface radius ratio for the case of a spherical geometry. Discharge power did not appear to influence the electron collection current substantially in the experiments so it is suggested in light of the model that the contactors are generally not limited by their ion production capabilities under conditions at which they were tested.

  16. Optimization of a He-Xe Hollow Cathode Discharge Laser.

    DTIC Science & Technology

    1982-12-01

    obtained by mixing the gases at the highest pressure required, taking the measurements, and then slowly opening valve #2 to the roughing system. The...or by the time the hollow cathode reached 60eC, whichever comes first. The anode voltages used for the efficiency comparisons are obtained from the...is within acceptable limits. In fact, if the measurements are accurate, power out comparisons should be valid by changing the "T" values and obtaining

  17. Optimization of hollow cathode discharge electrode for damage free remote plasma removal process for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Cho, Tae S.; Han, Qing; Yang, Dongqing; Park, Soonam; Lubomirsky, Dima; Venkataraman, Shankar

    2016-05-01

    Cone-shaped hollow cathode electrode configuration for a damage free remote plasma removal process has been optimized for given pressures based on Paschen characteristic curves, voltage-current characteristics and time-resolved discharge observations as well as oxide film removal performances. Remote plasmas have been generated in two types of cone-shaped electrodes with mixtures of He, NF3, and NH3 for pressure range of 1-30 Torr. Paschen characteristic curves and voltage-current (V-I) characteristics define an operating pressure for low breakdown voltage and the hollow cathode effect to minimize the particles. Sinusoidal voltage waveform and asymmetry electrode configuration alternate the glow discharge and hollow cathode discharge modes in a cycle. The current and infrared emission intensity from the glow discharge increases together for both cone-shaped electrodes with increasing pressure, whereas the hollow cathode discharge plasma emits strong infrared only when pD condition is satisfied. For the wide cone electrode configuration, high voltage operation at higher pressure results in particle contamination on the processed wafer by high energy ion bombardment. Operating at optimum pressure for a given electrode configuration shows faster oxide etch rate with better uniformity over a whole 300 mm wafer.

  18. The Monte-Carlo get finished in hollow cathode theory -- a source equation is incoming!

    NASA Astrophysics Data System (ADS)

    Gorin, Vladimir

    2008-10-01

    The hollow cathode effect (HCE) in glow discharge occurred rather hard bean for theoreticians. Classical local Engel and Shtenbek cathode dark space theory does not work under conditions of HCE because it is not possible to neglect inertia of electron here. The electron distribution function has many features and it is far from Maxwellian one. The absence of non-local source model from Paschen invention of a hollow cathode in 1916 till today forced to use Monte-Carlo methods. It meant an absence of any equation for a source of ionization in a hollow cathode! Time to find this equation is coming. It is an integral equation, which is derived from kinetic equation and determines a non-local dependence of ionization source on electric field through phase trajectories of electron motion. When simplification of local dependence is possible, the equation can be transformed into ordinary differential equation and then it is coincident with a continuity equation of classical Engel-Shtenbek model. In joining with field equations the source equation enables to calculate current voltage characteristics of simple glow and hollow cathode discharge and see the HCE in mathematical simulation.

  19. The Glowing Eye of NGC 6751

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Astronomers using NASA's Hubble Space Telescope have obtained images of the strikingly unusual planetary nebula, NGC 6751. Glowing in the constellation Aquila like a giant eye, the nebula is a cloud of gas ejected several thousand years ago from the hot star visible in its center. The Hubble observations were obtained in 1998 with the Wide Field and Planetary Camera 2 (WFPC2) by a team of astronomers led by Arsen Hajian of the U.S. Naval Observatory in Washington, DC. The Hubble Heritage team, working at the Space Telescope Science Institute in Baltimore, has prepared this color rendition by combining the Hajian team's WFPC2 images taken through three different color filters that isolate nebular gases of different temperatures. The nebula shows several remarkable and poorly understood features. Blue regions mark the hottest glowing gas, which forms a roughly circular ring around the central stellar remnant. Orange and red show the locations of cooler gas. The cool gas tends to lie in long streamers pointing away from the central star, and in a surrounding, tattered-looking ring at the outer edge of the nebula. The origin of these cooler clouds within the nebula is still uncertain, but the streamers are clear evidence that their shapes are affected by radiation and stellar winds from the hot star at the center.

  20. Glow discharge based device for solving mazes

    SciTech Connect

    Dubinov, Alexander E. Mironenko, Maxim S.; Selemir, Victor D.; Maksimov, Artem N.; Pylayev, Nikolay A.

    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.

  1. Glow discharge based device for solving mazes

    NASA Astrophysics Data System (ADS)

    Dubinov, Alexander E.; Maksimov, Artem N.; Mironenko, Maxim S.; Pylayev, Nikolay A.; Selemir, Victor D.

    2014-09-01

    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.

  2. Heat transfer in a longitudinal glow discharge

    NASA Astrophysics Data System (ADS)

    Yunusov, R. F.

    2017-01-01

    This article is devoted to the experimental study of heat transfer in a longitudinal glow discharge. The discharge was ignited in the discharge chamber (DC), consisting of a glass tube 10 mm in diameter and two electrodes. Copper electrodes were placed in the side branches, so that the average distance between them was 9 cm. The discharge pressure was varied in the range of P = (2.5 – 8.5) kPa. The air flow rate was varied from zero to G = 0.06 g / s. Current was varied in the range of I = (30-80) mA. Current-voltage characteristics of the discharge had falling form, and the voltage was varied in the range of U = (1-2) kV. The temperature of neutral particles in the plasma glow discharge was measured by six thermocouples, which were insertedon radius of DC. The aim of the article was to compare achieved experiment data with theoretical studies: recombination and diffusion plasma models.

  3. Acting green elicits a literal warm glow

    NASA Astrophysics Data System (ADS)

    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.

  4. Anode jet in a high-current vacuum arc

    NASA Astrophysics Data System (ADS)

    Popov, S. A.; Schneider, A. V.; Batrakov, A. V.; Sandolache, G.; Rowe, S. W.; Markov, A. B.; Zyul'kova, L. A.

    2012-07-01

    A stable intense jet with a clear-cut bright sheath has been detected on the anode of a 10-ms-long high-current vacuum arc with a current amplitude of 15 kA. The jet is adjacent to the hot spot of a molten metal on the anode surface. The primary light of the jet is emitted by neutrals. The sheath of the jet is surrounded by an ion-induced diffuse glow. The anode jet arises from interaction between the cathode and anode plasmas. Because of this, the size of the jet inversely depends on the current of the arc and the jet becomes observable only by the end of the current pulse. This object (anode jet with a bright sheath) is well reproducible when the arc is initiated between copper-chromium electrodes. In the case of pure copper electrodes, such objects occur randomly and appear at long projections of the molten metal, where heat release is hampered, and at large drops moving in the interelectrode gap. This means that the anode evaporation intensity is crucial for the appearance of bright-sheath jets.

  5. Hollow-Fiber Clinostat

    NASA Technical Reports Server (NTRS)

    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.

  6. Hollow-Fiber Clinostat

    NASA Technical Reports Server (NTRS)

    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.

  7. Hollow cathode apparatus

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1984-01-01

    A hollow cathode apparatus is described, which can be rapidly and reliably started. An ignitor positioned upstream from the hollow cathode, generates a puff of plasma that flows with the primary gas to be ionized through the cathode. The plasma puff creates a high voltage breakdown between the downstream end of the cathode and a keeper electrode, to heat the cathode to an electron-emitting temperature.

  8. Hollow nuclear matter

    NASA Astrophysics Data System (ADS)

    Yong, Gao-Chan

    2016-01-01

    It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. The size of the inner bubble in these matter is affected by the charge number of nuclear matter. The existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.

  9. Space vehicle glow measurements on STS 41-D

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Swenson, G. R.; Clifton, K. S.; Gause, R.; Leger, L.; Garriott, O. K.

    1985-01-01

    A flight experiment using a hand-held, image-intensified spectrographic camera was performed on mission 41-D. The instrument enabled the photographic documentation of the position of the spectral slit on the image to be subjected to spectrographic analysis. Because of this instrument feature, the spectrum of the glow on the Shuttle tail pod could be clearly separated from spectrum of the scattered light from the Orbiter. From the measurements it is clear that the spectrum of the glow is a continuum in the passband of the instrument between 4200 A and 8000 A. The measured spectral resolution of the instrument was 35 A. The scattered light from the Orbiter surfaces distinctly show the components of the earth's airglow at 5577 A and 7620 A. On the same flight material samples were also carried by the Orbiter attached to the Remote Manipulating System arm. These samples were representative of the material overcoatings used on the space telescope. The altitude of the 41-D flight was 290 km, instead of the 220 km which was originally planned for this experiment. The signal to noise ratio in the material glow discrimination experiment was quite low. This made it difficult to draw strong conclusions regarding the glow propensity of the materials. Nevertheless it was clear that polyethylene produces a very weak glow, while most black overcoating materials produce significant glow. MgF2 was also found to produce a relatively intense glow.

  10. FLUORINE CELL ANODE ASSEMBLY

    DOEpatents

    Cable, R.E.; Goode, W.B. Jr.; Henderson, W.K.; Montillon, G.H.

    1962-06-26

    An improved anode assembly is deslgned for use in electrolytlc cells ln the productlon of hydrogen and fluorlne from a moIten electrolyte. The anode assembly comprises a copper post, a copper hanger supported by the post, a plurality of carbon anode members, and bolt means for clamplng half of the anode members to one slde of the hanger and for clamplng the other half of the anode members to the other slde of the hanger. The heads of the clamplng bolts are recessed withln the anode members and carbon plugs are inserted ln the recesses above the bolt heads to protect the boIts agalnst corroslon. A copper washer is provided under the head of each clamplng boIt such that the anode members can be tightly clamped to the hanger with a resultant low anode jolnt resistance. (AEC)

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

    PubMed

    Levkovich, Tatiana; Poutahidis, Theofilos; 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.

  12. Juno Captures Jupiter Glow in Infrared Light

    NASA Image and Video Library

    2016-09-02

    As NASA's Juno spacecraft approached Jupiter on Aug. 27, 2016, the Jovian Infrared Auroral Mapper (JIRAM) instrument captured the planet's glow in infrared light. The video is composed of 580 images collected over a period of about nine hours while Jupiter completed nearly a full rotation on its axis. The video shows the two parts composing the JIRAM imager: the lower one, in a red color scale, is used for mapping the planet's thermal emission at wavelengths around 4.8 microns; the upper one, in a blue color scale, is used to map the auroras at wavelengths around 3.45 microns. In this case the exposure time of the imager was optimized to observe the planet's thermal emission. However, it is possible to see a faint aurora and Jupiter's moon Io approaching the planet. The Great Red Spot is also visible just south of the planet's equator. A movie is available at http://photojournal.jpl.nasa.gov/catalog/PIA21036

  13. Shock wave propagation in glow discharges

    NASA Astrophysics Data System (ADS)

    Ganguly, B. N.

    1998-10-01

    The modification of acoustic shock wave propagation characteristics in a 25 cm long positive column low pressure (10 to 50 Torr), low current density (2 to 10 mA/cm^2) argon and N2 dc discharges have been measured by laser beam deflection technique. The simultaneous multi point shock velocity, dispersion and damping have been measured both inside and outside the glow discharge region. The local shock velocity is found to increase with the increased propagation path length through the discharge; for Mach number greater than 1.7 the upstream velocity exceeded the downstream velocity in contrast to the opposite behavior in neutral gas. The damping and dispersion are also dependent on the propagation distance. The recovery of the shock dispersion and damping in the post discharge region, for a given discharge condition, are functions of the initial Mach number. The optical measurement of the wall and the gas (rotational) temperatures suggest the observed shock features can not be solely explained by the gas heating in a self sustained discharge. The results are similar for both Ar and N2 discharges showing that vibrational excitation and relaxation are not essential^1. The explanation of the observed weak shock propagation properties in a glow discharge appears to require long range cooperative interactions that enhance heavy particle collisional energy transfer rates for the measured discharge conditions. Unlike collisional shock wave propagation in highly ionized plasmas^2,3, the exact energy coupling mechanism between the nonequilibrium weakly ionized plasma and shock is not understood. 1. A.I. Osipov and A.V. Uvarov, Sov. Phys. Usp. 35, 903 (1992) and other references there in. 2. M. Casanova, O. Larroche and J-P Matte, Phys. Rev. Lett. 67, 2143 (1991). 3. M.C.M. van de Sanden, R. van den Bercken and D.C. Schram, Plasma Sources Sci.Technol. 3, 511 (1994).

  14. Current self-limitation of the nanosecond hollow cathode discharge

    NASA Astrophysics Data System (ADS)

    Levko, Dmitry

    2017-08-01

    The nanosecond hollow cathode discharge in argon gas at the pressure of 1-10 Torr is studied using 2D particle-in-cell Monte Carlo collisions model. We obtain that at the low gas pressure discharge operates in the plane-to-plane mode. This mode allows the generation of energetic electrons (>1 keV) in the gap between the cathode and the anode. However, these electrons do not form the focused beam. At higher pressures, the rather dense plasma penetrates inside the cathode which allows the generation of energetic electrons inside the cathode. However, since the energy relaxation length of 1 keV electrons is shorter than the cathode-anode gap, these electrons dissipate almost all their energy in collisions with neutrals during their propagation toward the anode. Additionally, the optimal conditions necessary for the generation of high-energy electrons are discussed.

  15. Drought Contingency Plan Mansfield Hollow Lake, Mansfield Hollow, Connecticut.

    DTIC Science & Technology

    1983-03-01

    AD -A 127 543 DROUGHT CONTINGENCY PLAN MANSFIELD HOLLOW LAKE / MANSFIELD HOLLOW CONNECTICUT(U) CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV MAR 83...3. RECIPICHT’S CATALOG NumlIER 4. TITLE (and Subliffe) S. TYp5 OF REPORT & PERIOD COVERED Drought Contingency Plan Mansfield Hollow Lake, Mansfield...oaigrySud Hollow , Connecticut 06. PERFORMING ONG. REPORT NUMBER 7. AUTHOR(a) 8. CONTRACT OR GRANT NUMSCIR(e) U.S. Army Corps of Engineers _ New

  16. Ring-cusp ion thruster with shell anode

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.; Rawlin, V. K.; Roman, R. F. (Inventor)

    1984-01-01

    An improved ion thruster for low specific impulse operation in the 1500 sec to 6000 sec range has a multicusp boundary field provided by high strength magnets on an iron anode shell which lengthens the paths of electrons from a hollow cathode assembly. A downstream anode pole piece in the form of an iron ring supports a ring of magnets to provide a more uniform beam profile. A cylindrical cathode magnet can be moved selectively in an axial direction along a feed tube to produce the desired magnetic field at the cathode tip.

  17. A model for explaining some features of shuttle glow

    NASA Technical Reports Server (NTRS)

    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.

  18. Fuel cell components and systems having carbon-containing electrically-conductive hollow fibers

    SciTech Connect

    Langry, Kevin C.; Farmer, Joseph C.

    2014-07-08

    According to one embodiment, a system includes a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst coupled to the hollow fiber, an anode extending along at least part of a length of the structure, and a cathode extending along at least part of the length of the structure, the cathode being on an opposite side of the hollow fiber as the anode. In another embodiment, a method includes acquiring a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst along one side thereof, adding an anode that extends along at least part of a length of the structure, and adding a cathode that extends along at least part of the length of the structure on an opposite side as the anode.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Proposal for a Workshop in the Physics and Application of Hollow Electrode Glow Switches

    DTIC Science & Technology

    1991-12-06

    Blindem Univ. of Padova 0316 Oslo 3 35100 Padova Norway Italy Dr. L. Pitchford Dr. D. Kaiabourniotis CNRS-U.P. Sabatier C.P.A.T. Univ. of Crete 118...corresponding experimental results. Self-Consistent Discharge Modeling J. P. Boeuf Centre de Physique Atomique de Toulouse (CNRS URA 277) Universit6 Paul Sabatier...Very High E/n L.C. Pitchford Centre de Physique Atomique URA 277 (CNRS) 31062 Toulouse France Abstract A simple, multi-beam model has been developed

  1. Hollow-Core Fiber Lamp

    NASA Technical Reports Server (NTRS)

    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.

  2. Hot hollow cathode gun assembly

    DOEpatents

    Zeren, J.D.

    1983-11-22

    A hot hollow cathode deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

  3. Vehicle/Atmosphere Interaction Glows: Far Ultraviolet, Visible, and Infrared

    NASA Technical Reports Server (NTRS)

    Swenson, G.

    1999-01-01

    Spacecraft glow information has been gathered from a number of spacecraft including Atmospheric and Dynamic satellites, and Space Shuttles (numerous flights) with dedicated pallet flow observations on STS-39 (DOD) and STS-62 (NASA). In addition, a larger number of laboratory experiments with low energy oxygen beam studies have made important contributions to glow understanding. The following report provides information on three engineering models developed for spacecraft glow including the far ultraviolet to ultraviolet (1400-4000 A), and infrared (0.9-40 microns) spectral regions. The models include effects resulting from atmospheric density/altitude, spacecraft temperature, spacecraft material, and ram angle. Glow brightness would be predicted as a function of distance from surfaces for all wavelengths.

  4. Organic thin film deposition in atmospheric pressure glow discharge

    SciTech Connect

    Okazaki, S.; Kogoma, M.; Yokoyama, T.; Kodama, M.; Nomiyama, H.; Ichinohe, K.

    1996-01-01

    The stabilization of a homogeneous glow discharge at atmospheric pressure has been studied since 1987. On flat surfaces, various plasma surface treatments and film depositions at atmospheric pressure have been examined. A practical application of the atmospheric pressure glow plasma on inner surfaces of flexible polyvinyl chloride tubes was tested for thin film deposition of polytetrafluoroethylene. Deposited film surfaces were characterized by ESCA and FT-IR/ATR measurements. Also SEM observation was done for platelet adhesion on the plasma treated polyvinyl chloride surface. These results showed remarkable enhancement in the inhibition to platelet adhesion on the inner surface of PVC tube, and homogeneous organic film deposition was confirmed. The deposition mechanism of polytetrafluoroethylene film in atmospheric pressure glow plasma is the same as the mechanism of film formation in the low pressure glow plasma, except for radical formation source. {copyright} {ital 1996 American Institute of Physics.}

  5. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    NASA Technical Reports Server (NTRS)

    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.

  6. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    NASA Technical Reports Server (NTRS)

    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.

  7. RF assisted Glow Discharge Condition experiment for SST-1 Tokamak

    NASA Astrophysics Data System (ADS)

    Raval, Dilip; Khan, Ziauddin; George, Siju; Dhanani, Kalpeshkumar R.; Paravastu, Yuvakiran; Semwal, Pratibha; Thankey, Prashant; Shoaib Khan, Mohammad; Kakati, Bharat; Pradhan, Subrata

    2017-04-01

    Impurity control reduces the radiation loss from plasma and hence enhances the plasma operation. Oxygen and water vapors are the most common impurities in tokamak devices. Water vapour can be reduced with extensive baking while in order to have a significant reduction in oxygen it is necessary to use glow discharge condition (GDC). RF assisted glow discharge cleaning system will be implemented to remove low z impurities at PFC installed SST-1 vacuum vessel. A RF assisted Glow discharge conditioning is studied at laboratory to find the optimum operating parameters in a view to implement at SST-1 tokamak. Helium is used as a fuel gas in the present experiment. It is observed that the ultimate impurity level is reduced significantly below to the accepted level for plasma operation after RF assisted GDC. The experimental findings of RF assisted Glow discharge conditioning is discussed in details in this paper.

  8. Glow discharge techniques for conditioning high vacuum systems

    SciTech Connect

    Dylla, H.F.

    1988-03-01

    A review is given of glow discharge techniques which are useful for conditioning vacuum vessels for high vacuum applications. Substantial development of glow discharge techniques has been done for the purpose of in-situ conditioning of the large ultrahigh vacuum systems for particle accelerators and magnetic fusion devices. In these applications the glow discharge treatments remove impurities from vessel surfaces in order to minimize particle-induced desorption coefficients. Cleaning mechanisms involve a mixture of sputtering and ion- (or neutral) induced desorption effects depending on the gas mixture (ArO/sub 2/ vs. H/sub 2/) and excitation method (DC, RF, and ECR). The author will review the methodology of glow discharge conditioning, diagnostic measurements provided by residual gas and surface composition analysis, and applications to vessel conditioning and materials processing. 76 refs., 16 figs.

  9. On the shape of the glow discharge channel

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. L.; Nikushchenko, E. M.

    2017-05-01

    Examples of the shapes of the glow discharge channel are presented. The discharge has been initiated in air at a pressure of 0.1 atm. The effective value and frequency of the discharge current are 30-70 mA and 50 Hz, respectively. It has been shown that, for these values of the current and pressure, thermal convection in a vacuum chamber and buoyancy (Archimedes force) are not major reasons for the specific parabolic shape of glow discharge.

  10. How do Colluvial Hollows Fill?

    NASA Astrophysics Data System (ADS)

    Hales, T. C.; Parker, R.; Mudd, S. M.; Grieve, S. W. D.

    2016-12-01

    In humid, soil-mantled mountains shallow landslides commonly initiate in colluvial hollows, areas where convergent topography can lead to high pore pressures during storms. Immediately post-landslide initiation, a thin veneer of colluvial material accumulates by small-scale slumping from landslide headscarps. Thereafter colluvium accumulates in hollows primarily through creep-dominated processes like tree throw and animal burrowing, recording the hillslope sediment flux since the last landslide event. We measured the post-landslide hillslope sediment flux in 30 colluvial hollows in the southern Appalachians using radiocarbon measurements collected from soil pits excavated at the centre of steep, landslide-prone hollows. We collected material from the soil-saprolite/bedrock boundary at each location for radiocarbon dating and dated different chemical fractions of the soil (humic acid, humin, charcoal) in an attempt to bracket the "true" age of the soil. We calculated infilling rates of each hollow by measuring soil depths in cross-hollow transects and dividing this by the age of the hollow. The interquartile range of hollow basal ages is 2278-8184 cal. yrs B.P., demonstrating the long return period of landslides in most colluvial hollows. Hillslope erosion rates calculated assuming a linear diffusion transport law show that the transport coefficient (diffusivity) of the hollows varied by 4 orders of magnitude 10-5 to 10-1 m2 yr-1, despite the hollows being formed in regionally consistent geology and vegetation. Uncertainty in the dating and hollow geometry measurements can, at most, account for an order of magnitude of that variability. Our results show that hollows have a phase of rapid infilling that slows through time, consistent with previous observations. Despite this, the oldest hollows show several orders of magnitude variation in the transport coefficient, suggesting local, hollow scale variations in process significantly affect hillslope erosion rates.

  11. The measurements of vehicle glow on the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Banks, P. M.; Nobles, R.; Garriott, O. K.; Hoffman, J.

    1983-01-01

    From the combined data set of glow observations on STS-3, STS-4 and STS-5 some of the properties of the shuttle glow were observed. Comparison of the STS-3 (240 km) and STS-5 (305 km) photographs show that the intensity of the glow is about a factor of 3.5 brighter on the low altitude (STS-3) flight. The orbiter was purposely rotated about the x axis in an experiment on STS-5 to observe the dependence of the intensity on the angle of incidence between the spacecraft surface normal and the velocity vector. For a relatively large angle between the velocity vector and the surface normal there is an appreciable glow, provided the surface is not shadowed by some other spacecraft structure. As the angle becomes less the glow intensifies. The grating experiments (STS-4 photography only, STS-5 image intensifier photography) provided a preliminary low resolution spectra of the spacecraft glow. Accurate wavelength calibrations of the STS-5 instrument permitted measuring of the spectrum and intensity of the Earth's airglow.

  12. Thermoluminescence glow curve analysis of natural onyx from Turkey.

    PubMed

    Dogan, Tamer; Toktamış, Hüseyin; Yüksel, Mehmet; Topaksu, Mustafa; Yazici, A Necmeddin

    2015-02-01

    In this study, the thermoluminesce (TL) properties of natural onyx were determined after β-irradiation ((90)Sr/(90)Y) at room temperature. The effect of the additive dose and variable heating rate for TL glow peaks of the sample were investigated. Computerized glow curve deconvolution (CGCD) methods were used to determine the number of peaks and kinetic parameters related to the TL glow peaks in natural onyx from Turkey. It was also determined kinetic parameters of onyx by means of the variable heating rate (VHR) method. The sample was exposed to β-irradiation between 2.4 Gy and 2.457 kGy. The CGCD methods showed that the glow curve of sample is the superposition of at least six first order components which were ascribed as P1-P6. The dose responses of some peaks have similar patterns and they follow linearity. The effect of heating rates on the response of dosimetric glow peaks of sample was studied. The maximum TL peak intensities of glow curve are decreasing with increasing heating rate and maximum TL peak intensities at 1 °C/s drops to 20% of the initial value when the sample is read at 6 °C/s.

  13. Investigation of vehicle glow in the far ultraviolet

    NASA Technical Reports Server (NTRS)

    Chakrabarti, S.; Sassen, T.

    1985-01-01

    To data, all vehicle glow observations have been conducted in the visible and near infrared wavelength regions. As the Space Telescope's wavelength coverage extends to the far ultraviolet range and current plasma theory of the spacecraft glow phenomena predicts bright glow intensities, a study of the ram glow effects in the 800-1400 angstrom region was undertaken. The data were collected between March 21-28, 1979, from 600 km altitude near local midnight by the University of California, Berkeley's extreme ultraviolet spectrometer on board the polar orbiting STP78-1 satellite. Data from several nighttime orbits obtained outside the South Atlantic Anomaly region and within + or - 30 deg magnetic latitude range were separated into forward (south viewing) and backward (north viewing) bins. Each of these binds was subdivided into three directional categories: (1) up (zenith angles 30-80 deg), (2) side (zenith angles 80-100 deg), and (3) down (zenith angles 120-150 deg). The maximum ram glow effects are expected in the side viewing directions. Our data include possible effects of ram glow signatures in the 800-1400 angstrom wavelength region.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Investigation of a high impedance magnetically insulated transmission line oscillator with hollow load

    NASA Astrophysics Data System (ADS)

    Zhou, Heng; Shu, Ting; Li, Zhi-qiang

    2012-09-01

    A novel high-impedance magnetically insulated transmission line oscillator (MILO) with greatly restrained power deposition on the anode has been investigated. Methods to increase the MILO impedance and decrease the anode current are discussed. A MILO with impedance of 30 Ω and power conversion efficiency of 25% is presented by particle-in-cell simulations. Compared with the previous MILO in our lab, the anode current of the proposed MILO is reduced about 50%, the power conversion efficiency doubles, and the power deposition on anode is reduced nearly one half. Furthermore, considerations for reducing the power deposition on load have also been carried out in MILO design, and the load current is reduced to 4.6 kA, only 17% of the total anode current. Finally, a hollow load was introduced to reduce the power deposition density on the load, without decreasing the power conversion efficiency.

  16. Investigation of a high impedance magnetically insulated transmission line oscillator with hollow load

    SciTech Connect

    Zhou Heng; Shu Ting; Li Zhiqiang

    2012-09-15

    A novel high-impedance magnetically insulated transmission line oscillator (MILO) with greatly restrained power deposition on the anode has been investigated. Methods to increase the MILO impedance and decrease the anode current are discussed. A MILO with impedance of 30 {Omega} and power conversion efficiency of 25% is presented by particle-in-cell simulations. Compared with the previous MILO in our lab, the anode current of the proposed MILO is reduced about 50%, the power conversion efficiency doubles, and the power deposition on anode is reduced nearly one half. Furthermore, considerations for reducing the power deposition on load have also been carried out in MILO design, and the load current is reduced to 4.6 kA, only 17% of the total anode current. Finally, a hollow load was introduced to reduce the power deposition density on the load, without decreasing the power conversion efficiency.

  17. Characterization of hollow cathode, ring cusp discharge chambers. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.

    1989-01-01

    An experimental study into the effects of changes in such physical design parameters as hollow cathode position, anode position and ring cusp magnetic field configuration and strength on discharge chamber performance, is described. The results are presented in terms of comparative plasma ion energy cost, extracted ion fraction and ion beam profile data. Such comparisons are used to demonstrate specific means by which changes in these design parameters induce changes in performance, i.e., through changes in the loss rates of primary electrons to the anode, of ions to discharge chamber walls or of ions to cathode and anode surfaces. Results show: (1) the rate of primary electron loss to the anode decreases as the anode is moved downstream of the ring cusp toward the screen grid, (2) the loss rate of ions to hollow cathode surfaces are excessive if the cathode is located upstream of a point of peak magnetic flux density on the discharge chamber centerline, and (3) the fraction of the ions produced that are lost to discharge chamber walls and ring magnet surfaces is reduced by positioning the magnet rings so the plasma density is uniform over the grid surface and so there are no steep magnetic flux density gradients near the walls through which ions can be lost by Bohm diffusion. The uniformity of the plasma density at the grids can also be improved by moving the point of primary electron injection into the discharge chamber off of the chamber centerline. Other results show the discharge chamber losses decrease when a filament cathode is substituted for a hollow cathode to the extent of the hollow cathode operating power. When plasma ion energy cost is determined in such a way that the cost of operating the hollow cathode is subtracted out, the performance using either electron source is similar.

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

    SciTech Connect

    Zhang, Fan; An, Yongling; Zhai, Wei; Gao, Xueping; Feng, Jinkui; Ci, Lijie; Xiong, Shenglin

    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.

  19. Influence of dust particles on glow discharge

    NASA Astrophysics Data System (ADS)

    Polyakov, D. N.; Shumova, V. V.; Vasilyak, L. M.; Fortov, V. E.

    2010-11-01

    The gas discharge-dust particle interaction for a dc discharge in air with micron-sized particles is investigated. The plasma of the dc column is described in the frame of diffusion approximation combined with the orbital motion limited approximation for ion and electron flow on the dust component surface. The problem is solved for dust particles of 2 μm radius, embedded in a uniform glow discharge column with a diameter of 16 mm at air pressure 0.5 torr, discharge current 0.5-3 mA and particle concentration up to 105 cm-3. The current-voltage characteristics as an easy-to-observe measure of the nonlocal dust influence on the total amount of charge carriers in the discharge, as well as the radial distributions of plasma components in the dc discharge, are calculated for different dust concentrations and discharge currents. The results are compared with recently published experimental data. The presence of dust particles leads to an increase of the longitudinal electric field due to additional loss of ions and electrons. A decrease of the radial electric field within the dust cloud under the action of dust particles results in an essential change of the electron concentration profile, down to the appearance of the local minimum at the axis of the discharge.

  20. Plasma sterilization using the RF glow discharge

    NASA Astrophysics Data System (ADS)

    Yang, Liqing; Chen, Jierong; Gao, Junling; Guo, Yafei

    2009-08-01

    In the present work, glow discharge oxygen plasma was used to sterilize the Pseudomonas aeruginosa on the polyethylene terephthalate (PET) sheets. In a self-designed plasma reaction equipment, active species (electron, ion, radical, UV light, etc.) were separated effectively, and the discharge area, afterglow area and remote area were plotted out in the plasma field. Before and after plasma treatment the cell morphology was studied by scanning electron microscopy (SEM). The results showed that after treatment of 30 s the germicidal effect is 4.26, 3. 84, 2.61, respectively in the three areas on the following conditions: discharge power was 40 W and gas flux was 20 cm 3/min. SEM results revealed the cell morphology before and after plasma treatment. The walls or cell membrane cracking was testified by determining the content of protein using coomassie light blue technique. The results from electron spin resonance spectroscopy (ESR) and double Langmuir electron probe showed that electron, ion and oxygen free radical played important roles in sterilization in the discharge area, but only oxygen radicals acted to sterilize the bacteria in the afterglow area and the remote area.

  1. Advances in the Remote Glow Discharge Experiment

    NASA Astrophysics Data System (ADS)

    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.

  2. Structure of anodized Al-Zr sputter deposited coatings and effect on optical appearance

    NASA Astrophysics Data System (ADS)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara; Rechendorff, Kristian; Dirscherl, Kai; Ambat, Rajan

    2014-10-01

    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 recycled aluminium alloys due to intermetallics.

  3. RHETT/EPDM Flight Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Manzella, David; Patterson, Michael; Pastel, Michael

    1997-01-01

    Under the sponsorship of the BMDO Russian Hall Electric Thruster Technology program two xenon hollow cathodes, a flight unit and a flight spare were fabricated, acceptance tested and delivered to the Naval Research Laboratory for use on the Electric Propulsion Demonstration Module. These hollow cathodes, based on the International Space Station plasma contactor design, were fabricated at the NASA Lewis Research Center for use with a D-55 anode layer thruster in the first on-orbit operational application of this technology. The 2.2 Ampere nominal emission current of this device was obtained with a xenon flow rate of 0.6 mg/s. Ignition of the cathode discharge was accomplished through preheating the active electron emitter with a resistive heating element before application of a 650 volt ignition pulse between the emitter and an external starting electrode. The successful acceptance testing of the Electric Propulsion Demonstration Module utilizing these cathodes demonstrated the suitability of cathodes based on barium impregnated inserts in an enclosed keeper configuration for use with Hall thruster propulsion systems.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Co-Flow Hollow Cathode Technology

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

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

  6. Self-Templated Synthesis of Ultrathin Nanosheets Constructed TiO2 Hollow Spheres with High Electrochemical Properties.

    PubMed

    Xie, Huiqi; Hu, Linfeng; Wu, Feilong; Chen, Min; Wu, Limin

    2016-11-01

    TiO2 is well-known nanomaterials and mostly used as solid nanoparticles, and normal hollow spheres for photocatalysts or electrode materials. In this study, a novel self-templated method is presented to successfully fabricate high-surface-area ultrathin nanosheets constructed TiO2 hollow spheres through the solvothermal treatment of the titanate-silicone composite particles combined with calcination. The uniquely structured hollow spheres exhibit excellent rate capability and good cycle stability even at a high current density of ≈10 C for the anode material of Li-ion battery.

  7. Self‐Templated Synthesis of Ultrathin Nanosheets Constructed TiO2 Hollow Spheres with High Electrochemical Properties

    PubMed Central

    Xie, Huiqi; Hu, Linfeng; Wu, Feilong; Chen, Min

    2016-01-01

    TiO2 is well‐known nanomaterials and mostly used as solid nanoparticles, and normal hollow spheres for photocatalysts or electrode materials. In this study, a novel self‐templated method is presented to successfully fabricate high‐surface‐area ultrathin nanosheets constructed TiO2 hollow spheres through the solvothermal treatment of the titanate–silicone composite particles combined with calcination. The uniquely structured hollow spheres exhibit excellent rate capability and good cycle stability even at a high current density of ≈10 C for the anode material of Li‐ion battery. PMID:27980991

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Carbonate fuel cell anodes

    DOEpatents

    Donado, R.A.; Hrdina, K.E.; Remick, R.J.

    1993-04-27

    A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process is described for production of the lithium ferrite containing anode by slipcasting.

  11. Carbonate fuel cell anodes

    DOEpatents

    Donado, Rafael A.; Hrdina, Kenneth E.; Remick, Robert J.

    1993-01-01

    A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process for production of the lithium ferrite containing anode by slipcasting.

  12. Nitrogen soft and hard X-ray emissions using different shapes of anodes in a 4-kJ plasma focus device

    SciTech Connect

    Mahtab, M. Habibi, M.

    2013-12-15

    The effect of different anode tip geometries on the intensity of soft and hard X-rays emitted from a 4-kJ plasma focus device is investigated using five different anode tips. The shapes of the uppermost region of these anodes (tips) have been cylindrical-flat, cylindrical-hollow, spherical-convex, cone-flat, and cone-hollow. For time-resolved measurement of the emitted X-rays, several BPX-65 pin diodes covered by different filters and a fast plastic scintillator are used. Experimental results have shown that, the highest intensity of the both soft and hard X-ray is recorded in cone-flat, spherical-convex, and cone-hollow tips, respectively. The use of cone-flat anode tip has augmented the emitted X-ray three times.

  13. Enhanced Glow Discharge Production of Oxygen

    NASA Technical Reports Server (NTRS)

    Ash, Robert; Zhong, Shi

    1998-01-01

    Studies starting in late seventies have shown Mars atmosphere can be used as a feedstock for oxygen production using simple chemical processing systems during early phases of the Mars exploration program. This approach has been recognized as one of the most important in-situ resource utilization (ISRU) concepts for enabling future round trip Mars missions. It was determined a decade ago that separation of oxygen can be accomplished efficiently by permeation through a silver membrane at temperatures well below 1000 K. This process involves adsorption of atomic oxygen on the surface and its subsequent diffusion through a silver lattice via an oxygen concentration gradient. We have determined recently that glow discharge can be used to liberate atomic oxygen from Mars atmosphere and that the oxygen can be collected through a silver permeation membrane. Recently, we demonstrated a substantial increase in energy efficiency of the process by applying a radio frequency discharge in combination with a silver permeation membrane. The experiments were performed using pure carbon dioxide in the pressure range equal to Mars surface conditions. Energy efficiency was defined as the ratio of the energy required to dissociate a unit mass of oxygen from carbon dioxide to the (electrical) energy consumed by the overall system during the dissociation and collection process. The research effort, started at NASA Langley Research Center, continued with this project. Oxygen production apparatus, built and operated under the research grant NAG1-1140 was relocated to the Atomic Beams Laboratory at ODU in July 1996, being since then in fall operation.

  14. Analysis of Thermoluminescence Glow Curves Using Derivatives of Different Orders.

    PubMed

    Karmakar, Mahua; Bhattacharyya, S; Sarkar, A; Mazumdar, P S; Singh, S D

    2017-01-16

    The suitability of the second derivative method for locating component peaks in complex thermoluminescence (TL) glow curves has been investigated in this work by considering both numerically simulated and experimental TL peaks. This technique is useful to acquire knowledge of the number of component peaks in a complex TL curve which in turn serves as a basic information before applying the deconvolution technique to the glow curve. To check the consistency of the results so obtained, we have also applied the first derivative technique to TL glow curves. It is well-known that kinetic order formalism fails for saturated TL peaks with heavy retrapping. Such peaks are usually broad and, to the best of our knowledge, have not yet been observed experimentally. The present derivative technique has been used to detect whether such broad peaks are truly single or not by considering a number of numerically simulated saturated glow curves with heavy retrapping where the conventional peak shape method fails. In all the cases considered here, the second derivative technique proves to be a potential candidate for estimating the number of peaks and their respective locations in a complex TL glow curve.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Hollow Microporous Organic Capsules

    PubMed Central

    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. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  17. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  18. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P.

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  19. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  20. Hollow Silicon Nanospheres Encapsulated with a Thin Carbon Shell: An Electrochemical Study

    SciTech Connect

    Ashuri, Maziar; He, Qianran; Liu, Yuzi; Zhang, Kan; Emani, Satyanarayana; Sawicki, Monica S.; Shamie, Jack; Shaw, Leon L.

    2016-10-01

    In this study we have investigated the electrochemical properties of hollow silicon nanospheres encapsulated with a thin carbon shell, HSi@C, as a potential candidate for lithium-ion battery anodes. Hollow Si nanospheres are formed using a templating method which is followed by carbon coating via carbonization of a pyrrole precursor to form HSi@C. The synthesis conditions and the resulting structure of HSi@C have been studied in detail to obtain the target design of hollow Si nanospheres encapsulated with a carbon shell. The HSi@C obtained exhibits much better electrochemical cycle stability than both micro-and nano-size silicon anodes and deliver a stable specific capacity of 700 mA h g(-1) after 100 cycles at a current density of 2 A g(-1) and 800 mA h g(-1) after 120 cycles at a current density of 1 A g(-1). The superior performance of HSi@C is attributed to the synergistic combination of the nanostructured material, the enhanced conductivity, and the presence of the central void space for Si expansion with little or no change in the volume of the entire HSi@C particle. This study is the first detailed investigation of the synthesis conditions to attain the desired structure of a hollow Si core with a conductive carbon shell. This study also offers guidelines to further enhance the specific capacity of HSi@C anodes in the future.

  1. Anodized dental implant surface.

    PubMed

    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.

  2. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    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…

  3. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    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…

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2016-06-15

    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.

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

    SciTech Connect

    Akhmet, Marat Fen, Mehmet Onur; Rafatov, Ismail

    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).].

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

    PubMed

    Akhmet, Marat; Rafatov, Ismail; Fen, Mehmet Onur

    2014-12-01

    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).].

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Thermal oxidation synthesis hollow MoO{sub 3} microspheres and their applications in lithium storage and gas-sensing

    SciTech Connect

    Zhao, Xinyu; Cao, Minhua; Hu, Changwen

    2013-06-01

    Graphical abstract: MoO{sub 3} hollow microspheres were synthesized via a facile and template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres exhibit an improved lithium storage and gas-sensing performance. Highlights: ► Hollow MoO{sub 3} microspheres were synthesized by thermal oxidation of hollow MoO{sub 2}. ► The MoO{sub 3} hollow microspheres have a relatively high specific surface area. ► The MoO{sub 3} hollow microspheres exhibit improved lithium storage performance. ► The MoO{sub 3} hollow microspheres show good responses to ammonia gas. - Abstract: In this paper, MoO{sub 3} hollow microspheres were synthesized via a facile and template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres have a relatively high specific surface area, and with such a feature, the as-synthesized MoO{sub 3} hollow microspheres have potential applications in Li-ion battery and gas-sensor. When tested as a Li-storage anode material, the MoO{sub 3} hollow microspheres show a higher discharge capacity of 1377.1 mA h g{sup −1} in the first discharge and a high reversible capacity of 780 mA h g{sup −1} after 100 cycles at a rate of 1 C. Furthermore, as a gas sensing material, the MoO{sub 3} hollow microspheres exhibit an improved sensitivity and short response/recovery time to trace levels of ammonia gas.

  10. Synthesis of metal nanoparticles by dual plasma electrolysis using atmospheric dc glow discharge in contact with liquid

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2014-04-01

    For the synthesis of metal nanoparticles in aqueous solution, we propose dual plasma electrolysis, which consists of a Hoffman electrolysis apparatus with two atmospheric glow discharge plasmas as electrodes instead of conventional metal electrodes immersed in a liquid. The plasma anode irradiates positive ions to the solution surface while the plasma cathode irradiates electrons to the solution surface. The dual plasma electrolysis system enables us to simultaneously investigate the influence of electron and positive ion irradiation to a solution surface on metal nanoparticle generation at the same current. In this work, we used aqueous solutions of AgNO3, HAuCl4, and their mixture. In dual plasma electrolysis with AgNO3, Ag nanoparticles were only synthesized on the plasma cathode side. This means that Ag nanoparticles are generated via the reduction of Ag+ by electrons. With HAuCl4 solution, Au nanoparticles were synthesized on both the plasma anode and plasma cathode sides. Ion irradiation with the plasma anode is more effective than electron irradiation for Au nanoparticle synthesis. This finding suggests that positive ions from the plasma trigger the dissociative reaction of AuCl4- at the plasma-liquid interface. When a AgNO3-HAuCl4 mixture was used, the synthesized nanoparticles have a structure consisting of a Au core covered with a Ag shell.

  11. Data requirements for verification of ram glow chemistry

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.

    1985-01-01

    A set of questions is posed regarding the surface chemistry producing the ram glow on the space shuttle. The questions surround verification of the chemical cycle involved in the physical processes leading to the glow. The questions, and a matrix of measurements required for most answers, are presented. The measurements include knowledge of the flux composition to and from a ram surface as well as spectroscopic signatures from the U to visible to IR. A pallet set of experiments proposed to accomplish the measurements is discussed. An interim experiment involving an available infrared instrument to be operated from the shuttle Orbiter cabin is also be discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Self-pulsing of hollow cathode discharge in various gases

    SciTech Connect

    Qin, Y.; He, F. Jiang, X. X.; Ouyang, J. T.; Xie, K.

    2014-07-15

    In this paper, we investigate the self-pulsing phenomenon of cavity discharge in a cylindrical hollow cathode in various gases including argon, helium, nitrogen, oxygen, and air. The current-voltage characteristics of the cavity discharge, the waveforms of the self-pulsing current and voltage as well as the repetition frequency were measured. The results show that the pulsing frequency ranges from a few to tens kilohertz and depends on the averaged current and the pressure in all gases. The pulsing frequency will increase with the averaged current and decrease with the pressure. The rising time of the current pulse is nearly constant in a given gas or mixture. The self-pulsing does not depend on the external ballast but is affected significantly by the external capacitor in parallel with the discharge cell. The low-current self-pulsing in hollow cathode discharge is the mode transition between Townsend and glow discharges. It can be described by the charging-discharging process of an equivalent circuit consisting of capacitors and resistors.

  14. Linear and Nonlinear Dust Acoustic Waves, Shocks and Stationary Structures in a dc-Glow-Discharge Dusty Plasma

    NASA Astrophysics Data System (ADS)

    Merlino, Robert

    2011-10-01

    In 1990, Rao, Shukla, and Yu (Planet. Space Sci. 38, 543) predicted the existence of the dust acoustic (DA) wave, a low-frequency (~ few Hz), compressional dust density wave that propagates through a dusty plasma at a phase speed ~ several cm/s. The DA wave was first observed by Chu et. al., (J. Phys. D: Appl. Phys. 27, 296, 1994) in an rf-produced dusty plasma, and by Barkan et. al., (Barkan et. al. Phys. Plasmas 2, 2161, 1995) who obtained video images of the DA wave trains using light scattering from a dust suspension confined in an anodic glow discharge plasma formed within a Q machine plasma. The dispersion relation for DAWs was measured by Thompson et. al., (Phys. Plasmas 4, 2331, 1997) in a dc glow discharge dusty plasma by modulating the discharge current at a set frequency. DAWs have been investigated by many groups both in weakly-coupled and strongly-coupled dusty plasmas (E. Thomas, Jr., Contrib. Plasma Phys. 49, 316, 2009). In most experiments where DA waves are present, the wave amplitude is relatively high, indicating that they are nonlinear. In this talk, results of our recent experiments on DAWs will be presented. The following experiments, performed in a dc glow-discharge dusty plasma will be described: (1) Observations of spontaneously excited nonlinear, cylindrical DAWs, which exhibit confluence of waves propagating at different speeds. (2) Investigations of self-steepening DAWs that develop into DA shocks with thicknesses comparable to the interparticle separation (Heinrich et. al., Phys. Rev. Lett. 103, 115001, 2009). (3) Measurements of the linear growth rates of DAWs excited in merging dust clouds. (4) The formation of stationary, stable dust density structures appearing as non-propagating DAWs (Heinrich et. al., Phys. Rev. E, in press, 2011). This work was performed in collaboration with S. H. Kim, J. R. Heinrich, and J. K. Meyer. Work supported by DOE Grant No. DE-FG01-04ER54795

  15. Mercury - the hollow planet

    NASA Astrophysics Data System (ADS)

    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

  16. Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge

    SciTech Connect

    El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A.; Rashed, U. M.; Hassouba, M. A.

    2012-05-15

    A dc plane glow discharge in a nitrogen-hydrogen (N{sub 2}-H{sub 2}) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H{sub 2} concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H{sub 2} concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H{sub 2} concentration.

  17. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    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.

  18. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 microns, a density of about I to about 6 pounds/ft3 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 bounded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cu ft and a compression strength of about 100 to about 1400 pounds/sq in.

  19. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 microns a density of about 1 to about 6 pounds/cubic ft and a volume change of 1 to about 20 percent 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 ft and a compression strength 2 of about 100 to about 1400 pounds/sq in.

  20. Hollow Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    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.

  1. Camp GLOW (Girls Leading Our World): Handbook for Volunteers.

    ERIC Educational Resources Information Center

    Peace Corps, Washington, DC. Information Collection and Exchange Div.

    Camp GLOW (Girls Leading Our World) began in Romania in 1995 as a weeklong leadership camp with the purpose of encouraging young women to become active citizens by building their self-esteem and confidence, increasing their self-awareness, and developing their skills in goal-setting, assertiveness, and career and life planning. Since that first…

  2. Degradation of Organics in a Glow Discharge Under Martian Conditions

    NASA Technical Reports Server (NTRS)

    Hintze, P. E.; Calle, L. M.; Calle, C. I.; Buhler, C. R.; Trigwell, S.; Starnes, J. W.; Schuerger, A. C.

    2006-01-01

    The primary objective of this project is to understand the consequences of glow electrical discharges on the chemistry and biology of Mars. The possibility was raised some time ago that the absence of organic material and carbonaceous matter in the Martian soil samples studied by the VikinG Landers might be due in part to an intrinsic atmospheric mechanism such as glow discharge. The high probability for dust interactions during Martian dust storms and dust devils, combined with the cold, dry climate of Mars most likely results in airborne dust that is highly charged. Such high electrostatic potentials generated during dust storms on Earth are not permitted in the low-pressure CO2 environment on Mars; therefore electrostatic energy released in the form of glow discharges is a highly likely phenomenon. Since glow discharge methods are used for cleaning and sterilizing surfaces throughout industry, the idea that dust in the Martian atmosphere undergoes a cleaning action many times over geologic time scales appears to be a plausible one.

  3. Mechanism of boriding from pastes in a glow discharge

    SciTech Connect

    Isakov, S.A.; Al'tshuler, S.A.

    1987-09-01

    The authors investigate the boridation of steel 45 from the standpoint of the glow-discharge dissociation of a borax paste and the plasma arc spraying of the resulting boron into the steel. The effects of process parameters on the impregnation of boron into the steel and its phase behavior in the boridation process are discussed.

  4. SkyGlowNet as a Vehicle for STEM Education

    NASA Astrophysics Data System (ADS)

    Flurchick, K. M.; Craine, E. R.; Culver, R. B.; Deal, S.; Foster, C.

    2013-06-01

    SkyGlowNet is an emerging network of internet-enabled sky brightness meters (iSBM) that continuously record and log sky brightness at the zenith of each network node site. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. The data are uploaded to the SkyGlowNet website, 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. Some of the data are periodically released to a public area on the website. In this presentation we describe the data formats and provide examples of both data content and the structure of the website. Early data from two nodes in the SkyGlowNet have been characterized, both quantitatively and qualitatively, by undergraduate students at NCAT. A summary of their work is presented here. These analyses are of utility in helping those new to looking at these data to understand how to interpret them. In particular, we demonstrate differences between effects on light at night and sky brightness due to astronomical cycles, atmospheric phenomena, and artificial lighting. Quantitative characterization of the data includes statistical analyses of parsed segments of the temporal data stream. An attempt is made to relate statistical metrics to specific types of phenomena.

  5. Synchronization between two coupled direct current glow discharge plasma sources

    SciTech Connect

    Chaubey, Neeraj; Mukherjee, S.; Sen, A.; Sekar Iyengar, A. N.

    2015-02-15

    Experimental results on the nonlinear dynamics of two coupled glow discharge plasma sources are presented. A variety of nonlinear phenomena including frequency synchronization and frequency pulling are observed as the coupling strength is varied. Numerical solutions of a model representation of the experiment consisting of two coupled asymmetric Van der Pol type equations are found to be in good agreement with the observed results.

  6. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    NASA Image and Video Library

    1994-03-05

    STS062-42-026 (4-18 March 1994) --- 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.

  7. Apparatus for determining glowing combustibility of thin fuels

    Treesearch

    D.C. Jones; A. Broido

    1971-01-01

    Leaflike samples, approximately 8 cm in diameter, are held at the end of a mechanical arm which reproducibly controls sample movement during the ignition and burn ing process. Glowing combustion is induced by bringing the sample into contact with a small loop in an electrically heated nichrome wire. The ultimate burned-out area is measured 1n an ultraviolet detection...

  8. Anodes - Technology review

    NASA Astrophysics Data System (ADS)

    Wallis, L.; Wills, R. G. A.

    2014-06-01

    Many electrochemical energy storage technologies utilize anodes that are specific to the chemistry of the device. Anodes must be designed for devices including primary and secondary batteries, fuel cells and capacitors. These applications include a diverse range of operational conditions, including aqueous, solid or organic media. This paper will provide a brief overview of anode technologies for medium (e.g. electric and hybrid electric vehicles) and large (e.g. integration of renewable energy generation to electrical networks) battery applications. Established and developing storage technologies will be discussed to provide an insight into how anodes (materials, manufacturing processes and modes of operation) differ between specific applications and devices. Lead-acid batteries are used as a case study to provide a practical example and guide discussion onto the question of future challenges and opportunities.

  9. Ring cusp/hollow cathode discharge chamber performance studies. [ion propulsion

    NASA Technical Reports Server (NTRS)

    Vaughn, J. A.; Wilbur, Paul J.

    1988-01-01

    An experimental study was performed to determine the effects of hollow cathode position, anode position, and ring cusp magnetic field configuration and strength on discharge chamber performance. The results are presented in terms of comparative plasma ion energy cost, extracted ion fraction, and beam profile data. Such comparisons are used to demonstrate whether changes in performance are caused by changes in the loss rate of primary electrons to the anode or the loss rate of ions to discharge chamber walls or cathode and anode surfaces. Results show: (1) the rate of primary electron loss to the anode decreases as the anode is moved downstream of the ring cusp toward the screen grid; (2) the loss rate of ions to hollow cathode surfaces are excessive if the cathode is located upstream of a point of peak magnetic flux density at the discharge chamber centerline; and (3) the fraction of the ions produced that are lost to discharge chamber walls and ring magnet surfaces is reduced by positioning of the magnet rings so the plasma density is uniform over the grid surface, and adjusting their strength to a level where it is sufficient to prevent excessive ion losses by Bohm diffusion.

  10. Microinfusion using hollow microneedles.

    PubMed

    Martanto, Wijaya; Moore, Jason S; Kashlan, Osama; Kamath, Rachna; Wang, Ping M; O'Neal, Jessica M; Prausnitz, Mark R

    2006-01-01

    The aim of the study is to determine the effect of experimental parameters on microinfusion through hollow microneedles into skin to optimize drug delivery protocols and identify rate-limiting barriers to flow. Glass microneedles were inserted to a depth of 720-1080 microm into human cadaver skin to microinfuse sulforhodamine solution at constant pressure. Flow rate was determined as a function of experimental parameters, such as microneedle insertion and retraction distance, infusion pressure, microneedle tip geometry, presence of hyaluronidase, and time. Single microneedles inserted into skin without retraction were able to infuse sulforhodamine solution into the skin at flow rates of 15-96 microl/h. Partial retraction of microneedles increased flow rate up to 11.6-fold. Infusion flow rate was also increased by greater insertion depth, larger infusion pressure, use of a beveled microneedle tip, and the presence of hyaluronidase such that flow rates ranging from 21 to 1130 microl/h were achieved. These effects can be explained by removing or overcoming the large flow resistance imposed by dense dermal tissue, compressed during microneedle insertion, which blocks flow from the needle tip. By partially retracting microneedles after insertion and other methods to overcome flow resistance of dense dermal tissue, protocols can be designed for hollow microneedles to microinfuse fluid at therapeutically relevant rates.

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

    SciTech Connect

    Li, D.; Liu, D. X. E-mail: mglin5g@gmail.com; Nie, Q. Y.; Li, H. P.; Chen, H. L.; Kong, M. G. E-mail: mglin5g@gmail.com

    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.

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

    NASA Astrophysics Data System (ADS)

    Sukhinin, G. I.; Fedoseev, A. V.; Ramazanov, T. S.; Amangaliyeva, R. Zh; Dosbalayev, M. K.; Jumabekov, A. N.

    2008-12-01

    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.

  13. Mixed mode oscillations in presence of inverted fireball in an excitable DC glow discharge magnetized plasma

    NASA Astrophysics Data System (ADS)

    Mitra, Vramori; Prakash, N. Hari; Solomon, Infant; Megalingam, Mariammal; Sekar Iyengar, A. N.; Marwan, Norbert; Kurths, Jürgen; Sarma, Arun; Sarma, Bornali

    2017-02-01

    The typical phenomena of mixed mode oscillations and their associated nonlinear behaviors have been investigated in collisionless magnetized plasma oscillations in a DC glow discharge plasma system. Plasma is produced between a cylindrical mesh grid and a constricted anode. A spherical mesh grid of 80% optical transparency is kept inside a cylindrical grid to produce an inverted fireball. Three Langmuir probes are kept in the ambient plasma to measure the floating potential fluctuations at different positions of the chamber. It has been observed that under certain conditions of discharge voltages and magnetic fields, the mixed mode oscillation phenomena (MMOs) appears, and it shows a sequential alteration with the variation of the magnetic fields and probe positions. Low frequency instability has been observed consistently in various experimental conditions. The mechanisms of the low frequency instabilities along with the origin of the MMOs have been qualitatively explained. Extensive linear and nonlinear analysis using techniques such as fast Fourier transform, recurrence quantification analysis, and the well-known statistical computing, skewness, and kurtosis are carried out to explore the complex dynamics of the MMO appearing in the plasma oscillations under various discharge conditions and external magnetic fields.

  14. 1D kinetic simulations of a short glow discharge in helium

    NASA Astrophysics Data System (ADS)

    Yuan, Chengxun; Bogdanov, E. A.; Eliseev, S. I.; Kudryavtsev, A. A.

    2017-07-01

    This paper presents a 1D model of a direct current glow discharge based on the solution of the kinetic Boltzmann equation in the two-term approximation. The model takes into account electron-electron coulomb collisions, the corresponding collision integral is written in both detailed and simplified forms. The Boltzmann equation for electrons is coupled with continuity equations for ions and metastable atoms and the Poisson equation for electric potential. Simulations are carried out self-consistently for the whole length of discharge in helium (from cathode to anode) for cases p = 1 Torr, L = 3.6 cm and p = 20 Torr, L = 1.8 mm, so that pL = 3.6 cm.Torr in both cases. It is shown that simulations based on the kinetic approach give lower values of electron temperature in plasma than fluid simulations. Peaks in spatial differential flux corresponding to the electrons originating from superelastic collisions and Penning ionization were observed in simulations. Different approaches of taking coulomb collisions into account give significantly different values of electron density and electron temperature in plasma. Analysis showed that using a simplified approach gives a non-zero contribution to the electron energy balance, which is comparable to energy losses on elastic and inelastic collisions and leads to significant errors and thus is not recommended.

  15. Control of plasma-liquid interaction of atmospheric DC glow discharge using liquid electrode

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Aoki, Ryuta; Nito, Aihito; Aoki, Takuya; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2014-10-01

    Atmospheric plasma in contact with liquid have a variety of interesting phenomena and applications. Previously, we investigated the fundamental characteristics of an atmospheric dc glow discharge using a liquid electrode with a miniature helium flow. We tried to control the plasma-liquid interaction by changing the plasma parameter such as gas species, liquid, and applied voltage. Sheath flow system enables another gas (N2, O2, Ar) flow to around the helium core flow. It can control the gas species around the discharge. When liquid (NaCl aq.) cathode DC discharge is generated, Na emission (588 nm) can be observed from liquid surface with increasing discharge current. Na emission strongly depends on the discharge current and liquid temperature. However, when Ar sheath flow is used, the intensity of Na becomes weak. When liquid anode DC discharge is generated, self-organized luminous pattern formation can be observed at the liquid surface. The pattern depends on existence of oxygen gas in gap. By changing the oxygen gas ratio in the gap, variety of pattern formation can be observed. The discharge in contact with liquid also can be used for synthesis of metal nanoparticles at plasma-liquid interface. Size and shape of nanoparticles depend on discharge gases. This work was supported financially in part by a Grant-in-Aid for Scientific Research on Innovative Areas (No 21110007) from MEXT, Japan.

  16. The use of matrix-specific calibrations for oxygen in analytical glow discharge spectrometry.

    PubMed

    Gonzalez-Gago, Cristina; Smid, Petr; Hofmann, Thomas; Venzago, Cornel; Hoffmann, Volker; Gruner, Wolfgang

    2014-11-01

    The performance of glow discharge optical emission spectroscopy and mass spectrometry for oxygen determination is investigated using a set of new conductive samples containing oxygen in the percent range in three different matrices (Al, Mg, and Cu) prepared by a sintering process. The sputtering rate corrected calibrations obtained at standard conditions for the 4 mm anode (700 V, 20 mA) in GD-OES are matrix independent for Mg and Al but not for Cu. The importance of a "blue shifted" line of oxygen at 130.22 nm (first reported by Köster) for quantitative analyses by GD-OES is confirmed. Matrix-specific calibrations for oxygen in GD-MS are presented. Two source concepts-fast flow (ELEMENT GD) and low gas flow (VG9000)-are evaluated obtaining higher sensitivity with the static flow source. Additional experiments using Ar-He mixtures or μs pulsed GD are carried out in ELEMENT GD aiming to improve the oxygen sensitivity.

  17. Managing voids of Si anodes in lithium ion batteries.

    PubMed

    Li, Xianglong; Zhi, Linjie

    2013-10-07

    The implementation of silicon (Si) in practical lithium ion battery electrodes has been hindered due to its large volume change and consequent structural and interfacial instabilities. Coating nanostructured Si with a second phase (e.g., carbon (C)) represents a very promising strategy for dealing with these critical issues facing Si-based electrodes. In this review article, we will outline recent advances in coating Si with engineered C matrices. By exemplifying hollow core-shell, core-hollow shell, and core-shell structured Si-C hybrid nanomaterials, we aim to highlight the importance of managing voids in designing such Si-C hybrid electrodes, and provide some scientific insights into the development of advanced Si-based anodes for next-generation lithium ion batteries.

  18. High Volumetric Capacity Three-Dimensionally Sphere-Caged Secondary Battery Anodes.

    PubMed

    Liu, Jinyun; Chen, Xi; Kim, Jinwoo; Zheng, Qiye; Ning, Hailong; Sun, Pengcheng; Huang, Xingjiu; Liu, Jinhuai; Niu, Junjie; Braun, Paul V

    2016-07-13

    High volumetric energy density secondary batteries are important for many applications, which has led to considerable efforts to replace the low volumetric capacity graphite-based anode common to most Li-ion batteries with a higher energy density anode. Because most high capacity anode materials expand significantly during charging, such anodes must contain sufficient porosity in the discharged state to enable the expansion, yet not excess porosity, which lowers the overall energy density. Here, we present a high volumetric capacity anode consisting of a three-dimensional (3D) nanocomposite formed in only a few steps which includes both a 3D structured Sn scaffold and a hollow Sn sphere within each cavity where all the free Sn surfaces are coated with carbon. The anode exhibits a high volumetric capacity of ∼1700 mA h cm(-3) over 200 cycles at 0.5C, and a capacity greater than 1200 mA h cm(-3) at 10C. Importantly, the anode can even be formed into a commercially relevant ∼100 μm thick form. When assembled into a full cell the anode shows a good compatibility with a commercial LiMn2O4 cathode. In situ TEM observations confirm the electrode design accommodates the necessary volume expansion during lithiation.

  19. Metal free nitrogen doped hollow mesoporous graphene-analogous spheres as effective electrocatalyst for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Meng, Hui; Xie, Fangyan; Yuan, Xiaoli; Yu, Wendan; Lin, Worong; Ouyang, Wenpeng; Yuan, Dingsheng

    2014-01-01

    Nitrogen-doped hollow mesoporous carbon spheres has been synthesized from mesoporous silica spheres using glycine as carbon and nitrogen precursor. The wall of the spheres is composed by broken graphene. The metal free nitrogen-doped hollow mesoporous carbon spheres are proven to be active electrocatalyst for the oxygen reduction reaction in alkaline solution. A unique advantage of the nitrogen-doped hollow mesoporous carbon sphere is its methanol-tolerant property because of the absence of active metal. The catalytic activity is ascribed to the pyridinic-nitrogen formed during pyrolysis and the graphene-like structure. To the best of our knowledge this is the first report on the nitrogen-doped hollow mesoporous carbon sphere as a metal-free electrocatalyst for the oxygen reduction reaction which is an important reaction in fuel cell. The prepared mesoporous carbon material can also be used as catalyst support and find application both in the anode and cathode of fuel cell.

  20. Hollow cathode-based plasma contactor experiments for electrodynamic tether

    NASA Astrophysics Data System (ADS)

    Patterson, Michael J.

    1987-01-01

    The role plasma contactors play in effective electrodynamic tether operation is discussed. Hollow cathodes and hollow cathode-based plasma sources have been identified as leading candidates for the electrodynamic tether plasma contactor. Present experimental efforts to evaluate the suitability of these devices as plasma contactors are reviewed. This research includes the definition of preliminary plasma contactor designs, and the characterization of their operation as electron collectors from a simulated space plasma. The discovery of an 'ignited mode' regime of high contactor efficiency and low impedance is discussed, as well as is the application of recent models of the plasma coupling process to contactor operation. Results indicate that ampere-level electron currents can be exchanged between hollow cathode-based plasma contactors and a dilute plasma in this regime. A discussion of design considerations for plasma contactors is given which includes expressions defining the total mass flow rate and power requirements of plasma contactors operating in both the cathodic and anodic regimes, and correlation of this to the tether current. Finally, future ground and spaceflight experiments are proposed to resolve critical issues of plasma contactor operation.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2016-09-09

    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.

  3. Hollow cathode-based plasma contactor experiments for electrodynamic tether

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.

    1987-01-01

    The role plasma contactors play in effective electrodynamic tether operation is discussed. Hollow cathodes and hollow cathode-based plasma sources have been identified as leading candidates for the electrodynamic tether plasma contactor. Present experimental efforts to evaluate the suitability of these devices as plasma contactors are reviewed. This research includes the definition of preliminary plasma contactor designs, and the characterization of their operation as electron collectors from a simulated space plasma. The discovery of an 'ignited mode' regime of high contactor efficiency and low impedance is discussed, as well as is the application of recent models of the plasma coupling process to contactor operation. Results indicate that ampere-level electron currents can be exchanged between hollow cathode-based plasma contactors and a dilute plasma in this regime. A discussion of design considerations for plasma contactors is given which includes expressions defining the total mass flow rate and power requirements of plasma contactors operating in both the cathodic and anodic regimes, and correlation of this to the tether current. Finally, future ground and spaceflight experiments are proposed to resolve critical issues of plasma contactor operation.

  4. [Automatic adjustment control system for DC glow discharge plasma source].

    PubMed

    Wan, Zhen-zhen; Wang, Yong-qing; Li, Xiao-jia; Wang, Hai-zhou; Shi, Ning

    2011-03-01

    There are three important parameters in the DC glow discharge process, the discharge current, discharge voltage and argon pressure in discharge source. These parameters influence each other during glow discharge process. This paper presents an automatic control system for DC glow discharge plasma source. This system collects and controls discharge voltage automatically by adjusting discharge source pressure while the discharge current is constant in the glow discharge process. The design concept, circuit principle and control program of this automatic control system are described. The accuracy is improved by this automatic control system with the method of reducing the complex operations and manual control errors. This system enhances the control accuracy of glow discharge voltage, and reduces the time to reach discharge voltage stability. The glow discharge voltage stability test results with automatic control system are provided as well, the accuracy with automatic control system is better than 1% FS which is improved from 4% FS by manual control. Time to reach discharge voltage stability has been shortened to within 30 s by automatic control from more than 90 s by manual control. Standard samples like middle-low alloy steel and tin bronze have been tested by this automatic control system. The concentration analysis precision has been significantly improved. The RSDs of all the test result are better than 3.5%. In middle-low alloy steel standard sample, the RSD range of concentration test result of Ti, Co and Mn elements is reduced from 3.0%-4.3% by manual control to 1.7%-2.4% by automatic control, and that for S and Mo is also reduced from 5.2%-5.9% to 3.3%-3.5%. In tin bronze standard sample, the RSD range of Sn, Zn and Al elements is reduced from 2.6%-4.4% to 1.0%-2.4%, and that for Si, Ni and Fe is reduced from 6.6%-13.9% to 2.6%-3.5%. The test data is also shown in this paper.

  5. 'Laguna Hollow'Undisturbed

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows the patch of soil at the bottom of the shallow depression dubbed 'Laguna Hollow' where the Mars Exploration Rover Spirit will soon begin trenching. Scientists are intrigued by the clustering of small pebbles and the crack-like fine lines, which indicate a coherent surface that expands and contracts. A number of processes can cause materials to expand and contract, including cycles of heating and cooling; freezing and thawing; and rising and falling of salty liquids within a substance. This false-color image was created using the blue, green and infrared filters of the rover's panoramic camera. Scientists chose this particular combination of filters to enhance the heterogeneity of the martian soil.

  6. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1986-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  7. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1989-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  8. Catalytic, hollow, refractory spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1987-01-01

    Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  9. Polypyrrole-Coated Zinc Ferrite Hollow Spheres with Improved Cycling Stability for Lithium-Ion Batteries.

    PubMed

    Sun, Xiaoran; Zhang, Hongwei; Zhou, Liang; Huang, Xiaodan; Yu, Chengzhong

    2016-07-01

    Here, ZnFe2 O4 double-shell hollow microspheres are designed to accommodate the large volume expansion during lithiation. A facile and efficient vapor-phase polymerization method has been developed to coat the ZnFe2 O4 hollow spheres with polypyrrole (PPY). The thin PPY coating improves not only the electronic conductivity but also the structural integrity, and thus the cycling stability of the ZnFe2 O4 hollow spheres. Our work sheds light on how to enhance the electrochemical performance of transition metal oxide-based anode materials by designing delicate nanostructures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

    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.

  11. Two-dimensional model of orificed micro-hollow cathode discharge for space application

    SciTech Connect

    Levko, D.; Krasik, Ya. E.; Vekselman, V.; Haber, I.

    2013-08-15

    In this paper, we describe results of self-consistent two-dimensional (x-z) particle-in-cell simulations, with a Monte Carlo collision model, of an orificed micro-hollow cathode operating in a planar diode geometry. The model includes thermionic electron emission with Schottky effect, secondary electron emission due to cathode bombardment by the plasma ions, several different collision processes, and a non-uniform xenon background gas density in the cathode-anode gap. Simulated results showing behavior of the plasma density, potential distribution, and energy flux towards the hollow cathode and orifice walls, are discussed. In addition, results of simulations showing the effect of different Xe gas pressures, orifice size, and cathode voltage, on operation of the micro-hollow cathode are presented.

  12. Porous Spinel Zn(x)Co(3-x)O(4) hollow polyhedra templated for high-rate lithium-ion batteries.

    PubMed

    Wu, Renbing; Qian, Xukun; Zhou, Kun; Wei, Jun; Lou, Jun; Ajayan, Pulickel M

    2014-06-24

    Nanostructured metal oxides with both anisotropic texture and hollow structures have attracted considerable attention with respect to improved electrochemical energy storage and enhanced catalytic activity. While synthetic strategies for the preparation of binary metal oxide hollow structures are well-established, the rational design and fabrication of complex ternary metal oxide with nonspherical hollow features is still a challenge. Herein, we report a simple and scalable strategy to fabricate highly symmetric porous ternary ZnxCo3-xO4 hollow polyhedra composed of nanosized building blocks, which involves a morphology-inherited and thermolysis-induced transformation of heterobimetallic zeolitic imidazolate frameworks. When tested as anode materials for lithium-ion batteries, these hollow polyhedra have exhibited excellent electrochemical performance with high reversible capacity, excellent cycling stability, and good rate capability.

  13. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  14. Dust-void formation in a dc glow discharge

    NASA Astrophysics Data System (ADS)

    Fedoseev, A. V.; Sukhinin, G. I.; Dosbolayev, M. K.; Ramazanov, T. S.

    2015-08-01

    Experimental investigations of dusty plasma parameters of a dc glow discharge were performed in a vertically oriented discharge tube. Under certain conditions, dust-free regions (voids) were formed in the center of the dust particle clouds that levitated in the strong electric field of a stratified positive column. A model for radial distribution of dusty plasma parameters of a dc glow discharge in inert gases was developed. The behavior of void formation was investigated for different discharge conditions (type of gas, discharge pressure, and discharge current) and dust particle parameters (particle radii and particle total number). It was shown that it is the ion drag force radial component that leads to the formation of voids. Both experimental and calculated results show that the higher the discharge current the wider dust-free region (void). The calculations also show that more pronounced voids are formed for dust particles with larger radii and under lower gas pressures.

  15. Photoresist Etching by Atmospheric Pressure Uniform-Glow Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Shouguo; Xu, Xiangyu; Zhao, Lingli; Ye, Tianchun

    2007-08-01

    An atmospheric pressure uniform-glow plasma (APUGP) operated by radio-frequency (RF) power at 13.56 MHz has been developed for etching, cleaning, surface treatment, and deposition of thin films among others. This plasma employs a capacitive coupling electrode design and produces a stable, volumetric glow discharge in a large disc area of 150 mm diameter using argon and oxygen mixture gas at atmospheric pressure. Its electrical characteristics were obtained by simultaneous measurements of voltage and current. In addition, typical photoresist-AZ9918 films spin-coated on 4-in. silicon wafers have been etched using this plasma source, which shows promise for replacing low-pressure plasma devices for some existing applications.

  16. Sensitive glow discharge ion source for aerosol and gas analysis

    DOEpatents

    Reilly, Peter T. A.

    2007-08-14

    A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.

  17. Hollow Retroreflectors Offer Solid Benefits

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A technician who lead a successful team of scientists, engineers, and other technicians in the design, fabrication, and characterization of cryogenic retroreflectors for the NASA Cassini/Composite Infrared Spectrometer (CIRS) mission to Saturn, developed a hollow retroreflector technology while working at NASA Goddard Space Flight Center. With 16 years of NASA experience, the technician teamed up with another NASA colleague and formed PROSystems, Inc., of Sharpsburg, Maryland, to provide the optics community with an alternative source for precision hollow retroreflectors. The company's hollow retroreflectors are front surface glass substrates assembled to provide many advantages over existing hollow retroreflectors and solid glass retroreflectors. Previous to this new technology, some companies chose not to use hollow retroreflectors due to large seam widths and loss of signal. The "tongue and groove" facet design of PROSystems's retroreflector allows for an extremely small seam width of .001 inches. Feedback from users is very positive regarding this characteristic. Most of PROSystems's primary customers mount the hollow retroreflectors in chrome steel balls for laser tracker targets in applications such as automobile manufacturing and spacecraft assembly.

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

    SciTech Connect

    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.

  19. OOPIC Simulation of a Cylindrical Magnetron Glow Discharge

    DTIC Science & Technology

    2008-03-01

    with the steel barrel serving as the cathode. The design of the PCD is being optimized using plasma simulation tools. Particle-in-Cell (PIC...this paper, the results from the simulations on the glow discharge near the internal surface of the barrel are compared to experimental data...trajectories from integration of the Newton- Lorentz equations of motion. Particle collisions are incorporated into the simulation using Monte Carlo

  20. Spacecraft Glow and the Eisg/skirt Experiment

    NASA Technical Reports Server (NTRS)

    Swenson, Gary R.; Ahmadjian, Mark; Jennings, Don; Visentine, Jim

    1992-01-01

    The objective of this experiment is to develop an understanding of the physical processes leading to spacecraft glow phenomena. The emphasis is to be on surface temperature and altitude effects. A complete understanding of the phenomena could be used to accomplish the following: (1) characterize optical instrument backgrounds; (2) provide guidelines for thermal insulations; (3) characterize material selection for flight optics and associated spacecraft; and (4) affect flight-operation altitude selection for relevant missions.

  1. Glow discharge sources for atomic and molecular analyses

    NASA Astrophysics Data System (ADS)

    Storey, Andrew Patrick

    Two types of glow discharges were used and characterized for chemical analysis. The flowing atmospheric pressure afterglow (FAPA) source, based on a helium glow discharge (GD), was utilized to analyze samples with molecular mass spectrometry. A second GD, operated at reduced pressure in argon, was employed to map the elemental composition of a solid surface with novel optical detection systems, enabling new applications and perspectives for GD emission spectrometry. Like many plasma-based ambient desorption-ionization sources being used around the world, the FAPA requires a supply of helium to operate effectively. With increased pressures on global helium supply and pricing, the use of an interrupted stream of helium for analysis was explored for vapor and solid samples. In addition to the mass spectra generated by the FAPA source, schlieren imaging and infrared thermography were employed to map the behavior of the source and its surroundings under the altered conditions. Additionally, a new annular microplasma variation of the FAPA source was developed and characterized. A spectroscopic imaging system that utilized an adjustable-tilt interference filter was used to map the elemental composition of a sample surface by glow discharge emission spectroscopy. This apparatus was compared to other GD imaging techniques for mapping elemental surface composition. The wide bandpass filter resulted in significant spectral interferences that could be partially overcome with chemometric data processing. Because time-resolved GD emission spectroscopy can provide fine depth-profiling measurements, a natural extension of GD imaging would be its application to three-dimensional characterization of samples. However, the simultaneous cathodic sputtering that occur across the sample results in a sampling process that is not completely predictable. These issues are frequently encountered when laterally varied samples are explored with glow discharge imaging techniques. These insights

  2. Inception of Snapover and Gas Induced Glow Discharges

    NASA Technical Reports Server (NTRS)

    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.

  3. Effect of glow discharge air plasma on grain crops seed

    SciTech Connect

    Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

    2000-02-01

    Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

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

    NASA Astrophysics Data System (ADS)

    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

  5. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1987-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  6. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1988-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  7. Analysis of thermoluminescent glow peaks of zoisite under beta irradiations

    SciTech Connect

    Ccallata, Henry Javier; Watanabe, Shigueo

    2010-08-04

    In this study, the thermoluminescence (TL) properties of natural crystal of zoisite were investigated after beta ({sup 90}Sr) irradiation at room temperature (RT). Zoisite, of chemical formula Ca{sub 2}Al{sub 3}(SiO{sub 4})(Si{sub 2}O{sub 7})O(OH), is found in Minas Gerais State, Brazil as natural mineral of silicate, member of the epidote group. The glow curve of a natural sample submitted to a heat treatment at 600 deg. C is composed of two broad peaks, centered at about 110-130 deg. C and another one at about 205-210 deg. C. A heating rate of 4 deg. C s{sup -1} was used in the temperature range from RT to 300 deg. C. The additive dose, T{sub m}-T{sub STOP} thermal cleaning, initial rise, variable heating rate and computerized glow curve deconvolution methods have shown that the glow curve is a superposition of six peaks at 100, 130, 155, 175, 200 and 230 deg. C. The trapping parameters for the individual peaks have been calculated. The TL dose response of 130 and 200 deg. C peaks has a linear response. Zoisite is a candidate for a TL dosimeter because of its high sensitivity.

  8. Spectral identification/elimination of molecular species in spacecraft glow

    NASA Astrophysics Data System (ADS)

    Green, B. D.; Marinelli, W. J.; Rawlins, W. T.

    1985-09-01

    Computer models of molecular electronic and vibrational emission intensities were developed. Known radiative emission rates (Einstein coefficients) permit the determination of relative excited state densities from spectral intensities. These codes were applied to the published spectra of glow above shuttle surface and to the Spacelab 1 results of Torr and Torr. The theoretical high-resolution spectra were convolved with the appropriate instrumental slit functions to allow accurate comparison with data. The published spacelab spectrum is complex but N2+ Meinel emission can be clearly identified in the ram spectrum. M2 First Positive emission does not correlate well with observed features, nor does the CN Red System. Spectral overlay comparisons are presented. The spectrum of glow above shuttle surfaces, in contrast to the ISO data, is not highly structured. Diatomic molecular emission was matched to the observed spectral shape. Source excitation mechanisms such as (oxygen atom)-(surface species) reaction product chemiluminescence, surface recombination, or resonance fluorescent re-emission will be discussed for each tentative assignment. These assignments are the necessary first analytical step toward mechanism identification. Different glow mechanisms will occur above surfaces under different orbital conditions.

  9. Space shuttle ram glow: Implication of NO2 recombination continuum

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Clifton, S.

    1985-01-01

    The ram glow data gathered to data from imaging experiments on space shuttle suggest the glow is a continuum (within 34 angstrom resolution); the continuum shape is such that the peak is near 7000 angstroms decreasing to the blue and red, and the average molecular travel leading to emission after leaving the surface is 20 cm (assuming isotropic scattering from the surface). Emission continuum is rare in molecular systems but the measured spectrum does resemble the laboratory spectrum of NO2 (B) recombination continuum. The thickness of the observed emission is consistent with the NO2 hypothesis given an exit velocity of approx. 2.5 km/sec (1.3 eV) which leaves approx. 3.7 eV of ramming OI energy available for unbonding the recombined NO2 from the surface. The NO2 is formed in a 3-body recombination of OI + NO + m = NO2 + m where OI originates from the atmosphere and NO is chemically formed on the surface from atmospheric NI and OI. The spacecraft surface then acts as the n for the reaction: Evidence exists from orbital mass spectrometer data that the NO and NO2 chemistry described in this process does occur on surfaces of spectrometer orifices in orbit. Surface temperature effects are likely a factor in the NO sticking efficiency and, therefore, glow intensities.

  10. Space shuttle Ram glow: Implication of NO2 recombination continuum

    NASA Astrophysics Data System (ADS)

    Swenson, G. R.; Mende, S. B.; Clifton, S.

    1985-09-01

    The ram glow data gathered to data from imaging experiments on space shuttle suggest the glow is a continuum (within 34 angstrom resolution); the continuum shape is such that the peak is near 7000 angstroms decreasing to the blue and red, and the average molecular travel leading to emission after leaving the surface is 20 cm (assuming isotropic scattering from the surface). Emission continuum is rare in molecular systems but the measured spectrum does resemble the laboratory spectrum of NO2 (B) recombination continuum. The thickness of the observed emission is consistent with the NO2 hypothesis given an exit velocity of approx. 2.5 km/sec (1.3 eV) which leaves approx. 3.7 eV of ramming OI energy available for unbonding the recombined NO2 from the surface. The NO2 is formed in a 3-body recombination of OI + NO + m = NO2 + m where OI originates from the atmosphere and NO is chemically formed on the surface from atmospheric NI and OI. The spacecraft surface then acts as the n for the reaction: Evidence exists from orbital mass spectrometer data that the NO and NO2 chemistry described in this process does occur on surfaces of spectrometer orifices in orbit. Surface temperature effects are likely a factor in the NO sticking efficiency and, therefore, glow intensities.

  11. The One Atmosphere Glow Discharge in Air: Phenomenology and Applications

    NASA Astrophysics Data System (ADS)

    Ben Gadri, Rami; Sherman, Daniel M.; Chen, Zhiyu; Karakaya, Fuat; Reece Roth, J.

    1999-10-01

    The existence of an atmospheric pressure RF glow plasma with the characteristics of a classical low pressure DC glow discharge has been experimentally and theoretically demonstrated [1, 2]. At the UTK Plasma Sciences Laboratory, the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) in air has been applied to a wide range of plasma processing applications. The technology is simple, technically attractive, and suitable for online treatment of webs and 3-dimensional workpieces. A parallel plate reactor and a Remote Exposure Reactor (RER) have been developed for direct plasma immersion and remote exposure, respectively. The RER is based on generating active species capable of sterilization and surface treatment in a uniform surface layer of the OAUGDP on planar panels [3], and convecting the active species to a remote chamber where the workpiece is located. A related surface plasma has been developed for indoor air filtration systems. In addition, the surface plasma on flat panels modified the boundary layer in wind tunnel tests to produce electrohydrodynamic (EHD) flow effects that can be used to increase or decrease aerodynamic drag [3]. [1] Massines et al., J. Appl. Phys., Vol. 83, N 6, pp 2950-2957, Mar. 1998. [2] J. R. Roth, "Industrial Plasma Engineering" Vol. I: Principles. Inst. Phys. Pub., Bristol and philadelphia, ISBN 0-7503-0318-2, 1995. [3] Roth et al., AIAA Paper 98-0328, 36th AIAA Meeting, Reno NV, 1998, Jan. 12-15.

  12. Spectral identification/elimination of molecular species in spacecraft glow

    NASA Technical Reports Server (NTRS)

    Green, B. D.; Marinelli, W. J.; Rawlins, W. T.

    1985-01-01

    Computer models of molecular electronic and vibrational emission intensities were developed. Known radiative emission rates (Einstein coefficients) permit the determination of relative excited state densities from spectral intensities. These codes were applied to the published spectra of glow above shuttle surface and to the Spacelab 1 results of Torr and Torr. The theoretical high-resolution spectra were convolved with the appropriate instrumental slit functions to allow accurate comparison with data. The published spacelab spectrum is complex but N2+ Meinel emission can be clearly identified in the ram spectrum. M2 First Positive emission does not correlate well with observed features, nor does the CN Red System. Spectral overlay comparisons are presented. The spectrum of glow above shuttle surfaces, in contrast to the ISO data, is not highly structured. Diatomic molecular emission was matched to the observed spectral shape. Source excitation mechanisms such as (oxygen atom)-(surface species) reaction product chemiluminescence, surface recombination, or resonance fluorescent re-emission will be discussed for each tentative assignment. These assignments are the necessary first analytical step toward mechanism identification. Different glow mechanisms will occur above surfaces under different orbital conditions.

  13. Anode initiated surface flashover switch

    SciTech Connect

    Brainard, John P.; Koss, Robert J.

    2003-04-29

    A high voltage surface flashover switch has a pair of electrodes spaced by an insulator. A high voltage is applied to an anode, which is smaller than the opposing, grounded, cathode. When a controllable source of electrons near the cathode is energized, the electrons are attracted to the anode where they reflect to the insulator and initiate anode to cathode breakdown.

  14. Planned investigation of infrared emissions associated with the induced spacecraft glow: A shuttle infrared glow experiment (SIRGE)

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; Jennings, D. E.

    1985-01-01

    The characteristics of infrared molecular emissions induced by energetic collisions between ambient atmospheric species and surfaces in Earth orbit are investigated, using a low-nitrogen-cooled filter wheel photometer covering the wavelength range 0.9-.5 microns with a resolving power Lambda/Delta Lambda of approximately 100. This resolving power is sufficient for identification of the molecular or atomic fluorescent spaces causing the glow.

  15. Numerical analysis of a hollow electrode plasma torch with a reversed polarity discharge for radioactive waste treatment

    NASA Astrophysics Data System (ADS)

    Park, Seung-Chul; Kim, Dong-Uk; Kim, Min-Ho; Seo, Jun-Ho; Yang, O.-Bong

    2013-11-01

    In this study, a numerical analysis is carried out in order to investigate the effects of the electrode configuration and the operation conditions on the arc flow structure and the performance of a hollow electrode plasma torch with a reversed polarity discharge. From the numerical results, a swirl injection of plasma gas and a hollowed cathode with a convergent entrance are found to help control the recirculation directions of backflows and the attachment position of the anode spot in the rear electrode. For example, the anode spot is observed to be moved to the central point of the blocked side in the rear electrode (the anode) when the plasma-forming gases are injected with a swirl. This attachment point is predicted to act as a stable anode spot for the transferred operation of the hollow electrode plasma torch with a reversed polarity discharge. In addition, the torch performance is analyzed for operation variables, such as the arc current and the gas flow rates. Similar to that of a conventional hollow electrode plasma torch, the scale-up of input power is accompanied by increases in the arc current and the gas flow rate while increasing the arc current brings about a deterioration in the torch efficiency, which is defined as the ratio of the exit enthalpy to the input power. On the other hand, the temperature profiles at the torch's exit plane show relatively negligible differences for various arc currents and gas flow rates due to the cathode spot being close to the torch exit. Based on these features, we expect the hollow electrode plasma torch with a reversed polarity discharge to be a promising tool for treating radioactive wastes in a single step, both as a non-transferred-type plasma incinerator for combustibles and as a transferred-type arc-melter for non-combustibles.

  16. Inert Anode Report

    SciTech Connect

    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.

  17. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  18. Anodes for alkaline electrolysis

    DOEpatents

    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.

  19. Detailed kinetic study of the thermoluminescence glow curve of synthetic quartz.

    PubMed

    Kitis, G; Pagonis, V; Carty, H; Tatsis, E

    2002-01-01

    A detailed kinetic analysis has been performed of the thermoluminescence (TL) glow curve of high purity synthetic quartz. The kinetic parameters of the glow peak at 110 degrees C were evaluated for doses ranging from 0.1 Gy to 100 Gy using glow curve deconvolution (GCD), initial rise, variable heating ratc and phosphorescence decay methods. All the methods gave results that agree within the experimental errors.

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

    DOEpatents

    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.

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

    DOEpatents

    Bird, Charles R.; Rockett, Paul D.

    1987-01-01

    An x-ray source 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.

  2. Study of Utilization of Automotive Diesel Glow Plug as AN IR Source

    NASA Astrophysics Data System (ADS)

    White, Allen R.

    2013-06-01

    Glow plugs are used in commercially available Diesel engines to assist in cold weather starting. These devices are an Infrared source that are consistent in their function and inexpensive. The operational temperature of a glow plug is in the lower range of globar operational temperatures (1100 C) but is still potentially spectroscopically useful. This study seeks to characterize these devices with respect to their utility as an infrared emission source. The spectral response of the glow plug to input current variation was measured as was the temporal stability of the emission spectrum. Finally, comparisions are made between the emission spectra of glow plugs and globars.

  3. A strategy to synthesize hollow micro/nanospheres with tunable shell thickness.

    PubMed

    Yang, Gongzheng; Cui, Hao; Wang, Chengxin

    2014-02-03

    A simple one-step direct templating method is developed to synthesize hollow carbon and sandwich-like ZnO/C/ZnO micro/nanospheres. The type and shell thickness of the final products can be controlled by simply adjusting the reaction temperature. The removal of the templates can also be easily controlled during the synthesis. At a low temperature, the templates remain in the products to form hollow sandwich-like micro/nanospheres. As the reaction temperature rises, the templates are consumed, which results in the preparation of hollow carbon micro/nanospheres. On the basis of a series of experiments, we propose a simple plausible mechanism to address the original strategy for synthesizing these hollow micro/nanospheres. Furthermore, the sandwich-like ZnO/C/ZnO nanospheres can be used as the anode in lithium-ion batteries, exhibiting an extraordinary cyclability and a high coulombic efficiency. This approach can be extended to the synthesis of other hollow spheres. Further investigation is underway in our group. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hierarchical CoS2@C hollow microspheres constructed by nanosheets with superior lithium storage

    NASA Astrophysics Data System (ADS)

    Chen, Weiwei; Li, Tingting; Hu, Qian; Li, Chengpin; Guo, Hong

    2015-07-01

    An effective approach of alcoholysis is employed to prepare hollow CoS2@C hybrid nanosheets aggregates as anode materials for Li-ion batteries. Amorphous carbon can be loaded on the CoS2 nanoparticles uniformly in the solvothermal alcoholysis process, and the subsequent calcination results of the formation of hollow structures. The capacity of the sample can remain stable as high as 720 mAhg-1 after 200 cycles, and it also exhibits good rate capacity. The nano-scaled characteristics of CoS2 nanosheets embedded in the aggregates ensure the electrode having a high capacity and the fast Li-ion diffusion in the electrode. The in-situ introduction of carbon renders the electrode having a good electronic conductivity and can effectively prevent the formation of polysulfide anions. The unique hollow structures can shorten the length of Li-ion diffusion, which is benefit for the rate performance. The hollow structure also offers a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. Therefore, the prepared hierarchical hollow CoS2@C materials constructed by nanosheets exhibit outstanding electrochemical performance.

  5. Hollow glass waveguides: New variations

    NASA Astrophysics Data System (ADS)

    Gibson, Daniel Joseph

    This study is an effort to develop new variations on the infrared silver-silver iodide hollow glass waveguide (HGW) with application specific properties. Four variations are presented: a HGW with a long, gradual taper, a HGW with a rectangular cross-section, curved HGW tips and a new all-dielectric hollow waveguide based on photonic bandgap guidance principles. A hollow glass waveguide tapered over its entire length offers ease of coupling at the proximal end and excellent flexibility at the distal end. Waveguides tapered from 1000 to 500 mum and 700 to 500 mum over 1.5 m were fabricated in this study. Compared to similarly sized non-tapered waveguides, laser losses for the tapered guides were high but decreased when bent. This behavior is contrary to that of non-tapered guides and an iterative ray tracing model was also developed to explain the observed loss characteristics of tapered hollow waveguides. Hollow glass waveguides with round profiles do not maintain the polarization state of the delivered radiation to any appreciable degree. HGWs with large- and small-aspect ratio rectangular cross sections were developed and shown to preserve polarization up to 96%, even when bent. The large aspect ratio guide was able to effectively rotate the transmitted polarization when twisted along its axis. Curved distal tips for medical and dental laser applications were developed by removing the low-OH silica fiber from commercially available stainless steel dental tips, and inserting HGWs of various sizes. The optical performances and heating profiles of the various configurations indicate the tips are suitable for certain medical applications, but the minimum bending radius is limited by the mechanical properties of the glass substrate. A small radii bending loss study confirms that propagating modes periodically couple as the radius of curvature is reduced. Through the application of the photonic bandgap (PBG) guidance, hollow waveguides can be made entirely from

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Transition characteristics of low-pressure discharges in a hollow cathode

    NASA Astrophysics Data System (ADS)

    Fu, Yangyang; Verboncoeur, John P.; Christlieb, Andrew J.; Wang, Xinxin

    2017-08-01

    Based on a two-dimensional (2-D) fluid model, the transition processes of discharges in a hollow cathode at low pressure are observed by changing three parameters, i.e., applied voltage U0, gas pressure p, and external circuit ballast resistance Rb. The voltage-current characteristic curves, electron density distributions, and electric potential distributions of different discharge operating points in a hollow cathode are obtained. The transition processes are characterized by the voltage-current characteristic curves, the electron density distributions, and the electrical potential distributions. The transition modes observed from the voltage-current characteristics include the low-current abnormal mode, normal mode, and high-current abnormal mode. Increasing the applied voltage U0 can have a similar effect on the discharge transition processes to decreasing the ballast resistance. By increasing U0 from 200 V to 500 V and decreasing Rb from 5000 kΩ to 100 kΩ independently, it is observed that the discharge transfers from the outside to the inside of the hollow cavity, thus forming the virtual anode potential. By increasing the gas pressure p from 50 Pa to 5 kPa, the discharge also moves into the hollow cavity from the outside; however, a further increase in the gas pressure leads to the discharge escaping from the hollow cavity. Simulation results and characterizations for different parameters are presented for the transition properties of low-pressure discharges in a hollow cathode. It is verified that the hollow cathode discharge only exists under certain ranges of the above parameters.

  8. Hollow sphere ceramic particles for abradable coatings

    SciTech Connect

    Longo, F.N.; Bader, N.F. III; Dorfman, M.R.

    1984-05-22

    A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate.

  9. Physical Processes in Hollow Cathode Discharge

    DTIC Science & Technology

    1989-12-01

    BUIT FiLE COPY NAVAL POSTGRADUATE SCHOOL Monterey, California 0DTIC x ,, , ’ AELECTEi<AU 17U THESIS L . PHYSICAL PROCESSES IN HOLLOW CATHODE...IPROJECT ITASK IWORK UNIT ELEMENT NO. NO. NO ACCESSION NO 11. TITLE (Include Security Classification) Physical Processes in Hollow Cathode Discharge 12...number) The hollow cathode is an effective source of dense, low energy plasma. Hollow cathodes find use in ion beam sources for laboratory and space

  10. Hollow nanotubular toroidal polymer microrings.

    PubMed

    Lee, Jiyeong; Baek, Kangkyun; Kim, Myungjin; Yun, Gyeongwon; Ko, Young Ho; Lee, Nam-Suk; Hwang, Ilha; Kim, Jeehong; Natarajan, Ramalingam; Park, Chan Gyung; Sung, Wokyung; Kim, Kimoon

    2014-02-01

    Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.

  11. New route for hollow materials

    NASA Astrophysics Data System (ADS)

    Rivaldo-Gómez, C. M.; Ferreira, F. F.; Landi, G. T.; Souza, J. A.

    2016-08-01

    Hollow micro/nano structures form an important family of functional materials. We have used the thermal oxidation process combined with the passage of electric current during a structural phase transition to disclose a colossal mass diffusion transfer of Ti ions. This combination points to a new route for fabrication of hollow materials. A structural phase transition at high temperature prepares the stage by giving mobility to Ti ions and releasing vacancies to the system. The electric current then drives an inward delocalization of vacancies, condensing into voids, and finally turning into a big hollow. This strong physical phenomenon leading to a colossal mass transfer through ionic diffusion is suggested to be driven by a combination of phase transition and electrical current followed by chemical reaction. We show this phenomenon for Ti leading to TiO2 microtube formation, but we believe that it can be used to other metals undergoing structural phase transition at high temperatures.

  12. New route for hollow materials

    PubMed Central

    Rivaldo-Gómez, C. M.; Ferreira, F. F.; Landi, G. T.; Souza, J. A.

    2016-01-01

    Hollow micro/nano structures form an important family of functional materials. We have used the thermal oxidation process combined with the passage of electric current during a structural phase transition to disclose a colossal mass diffusion transfer of Ti ions. This combination points to a new route for fabrication of hollow materials. A structural phase transition at high temperature prepares the stage by giving mobility to Ti ions and releasing vacancies to the system. The electric current then drives an inward delocalization of vacancies, condensing into voids, and finally turning into a big hollow. This strong physical phenomenon leading to a colossal mass transfer through ionic diffusion is suggested to be driven by a combination of phase transition and electrical current followed by chemical reaction. We show this phenomenon for Ti leading to TiO2 microtube formation, but we believe that it can be used to other metals undergoing structural phase transition at high temperatures. PMID:27554448

  13. Microstructure tailoring of the nickel oxide-Yttria-stabilized zirconia hollow fibers toward high-performance microtubular solid oxide fuel cells.

    PubMed

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

    2014-11-12

    NiO-yttria-stabilized zirconia (YSZ) hollow fiber anode support with different microstructures was prepared using a phase-inversion method. The effect of the solid loading of the phase-inversion suspensions on the microstructure development of the NiO-YSZ anode support was investigated. Solid loading in the suspension was found to have an important influence on the microstructure of the NiO-YSZ anode support and viscosity-related viscous fingering mechanism can be adopted to explain the pore formation mechanism of the as-prepared hollow fibers. NiO-YSZ anode-supported microtubular solid oxide fuel cells (SOFCs) with different anode microstructures were fabricated and tested, and the correlation between the anode support microstructures, porosity, gas permeability, electrical conductivity, and the cell electrochemical performance was discussed. Microtubular SOFCs with a cell configuration of Ni-YSZ/YSZ/YSZ-LSM (LSM = (La(0.8)Sr(0.2))(0.95)MnO(3-x)) and optimized anode microstructure show cell output power density of 833.9 mW cm(-2) at 750 °C using humidified H2 as fuel and ambient air as oxidant.

  14. Fabrication of porous anodic alumina using normal anodization and pulse anodization

    NASA Astrophysics Data System (ADS)

    Chin, I. K.; Yam, F. K.; Hassan, Z.

    2015-05-01

    This article reports on the fabrication of porous anodic alumina (PAA) by two-step anodizing the low purity commercial aluminum sheets at room temperature. Different variations of the second-step anodization were conducted: normal anodization (NA) with direct current potential difference; pulse anodization (PA) alternate between potential differences of 10 V and 0 V; hybrid pulse anodization (HPA) alternate between potential differences of 10 V and -2 V. The method influenced the film homogeneity of the PAA and the most homogeneous structure was obtained via PA. The morphological properties are further elucidated using measured current-transient profiles. The absent of current rise profile in PA indicates the anodization temperature and dissolution of the PAA structure were greatly reduced by alternating potential differences.

  15. Lunar Horizon Glow: A Quantitative Indicator of Exospheric Dust

    NASA Astrophysics Data System (ADS)

    Glenar, D. A.; Stubbs, T. J.; Vondrak, R. R.

    2008-12-01

    During the Apollo missions, horizon glow (HG) was observed by astronauts in lunar orbit just prior to orbital sunrise. These observations were further supported by excess brightness which appeared along the horizon in coronal photographs from Apollo 15 and 17. Horizon glow may also be present in star tracker measurements acquired during the Clementine mission, though it would be heavily masked by coronal and zodiacal light (CZL). The most likely cause of HG is thought to be forward scattering of sunlight by submicron dust grains in the lunar exosphere above the terminator, extending to 10's of km or higher in altitude. Such a dust population is thought to arise from charged lunar dust that has been electrostatically lofted from the surface, since strong surface electric fields are believed to exist at the terminator. Additional contributions to exospheric dust will arise from meteoritic ejecta. With many missions now returning to the Moon, it is important to be able to distinguish and quantify the observable sources of UV-VIS optical emission, specifically HG from lunar exospheric dust, CZL, and line emission from exospheric gases. We have developed a code which simulates 3D (2D spatial plus spectral) intensities of horizon glow arising from lunar exospheric dust, as it would be viewed from an orbiter in lunar shadow. The dust vertical profile used is the semi-empirical model proposed by Murphy and Vondrak. Dust scattering properties as a function of grain size are computed using Mie Theory. The code also incorporates CZL intensities as formulated by Hahn et al., as well as Na D-line emission as observed by Potter and Morgan, in order to contrast these three emission sources near the limb via their distinct spatial distributions, spectral intensities and dependence on solar elongation angle. We include a simulation of lunar HG, as it might be observed by the UV/Vis spectrometer aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE).

  16. Pediatric and young adult exposure to chemiluminescent glow sticks.

    PubMed

    Hoffman, Robert J; Nelson, Lewis S; Hoffman, Robert S

    2002-09-01

    Although chemiluminescent plastic rods, commonly called "glow sticks" or "light sticks," are typically considered to be minimally toxic or nontoxic, published data about exposure to these products are scarce. To test our hypothesis that exposure to chemiluminescent products is unlikely to result in significant morbidity or mortality and to describe factors associated with exposure by reviewing reports to our urban poison control center of human exposure to chemiluminescent products. Pediatric and young adult exposure to chemiluminescent products reported between January 1, 2000, and April 1, 2001, to our poison control center were evaluated with regard to demographic group, type of product involved, circumstances of exposure, symptoms, and management. Reported routes of exposure (n = 118) included ingestion (n = 108), ocular (n = 9), and dermal exposure (n = 1). Only patients exposed to chemiluminescent fluid from a leaking container reported symptoms (n = 27). Symptoms were limited to transient irritation of the exposure site, and no systemic toxicity occurred. All adults (n = 4) inadvertently ruptured or swallowed intact light sticks while at a dance club or dance party. Most exposure and all adult exposure occurred on holidays or weekends. Most incidences of exposure to chemiluminescent products involve asymptomatic ingestion of fluid that leaks from glow sticks or ingestion of an intact glow stick. Symptoms occur after exposure to chemiluminescent fluid and consist of transient irritation at the site of exposure. The clustering of reported exposure on weekends and in dance clubs and parties coupled with a lack of occupational or workplace exposure suggest that recreational use is a major contributory factor. Exposure to chemiluminescent products infrequently resulted in symptoms and the symptoms reported were minor. Exposure to chemiluminescent products as described is unlikely to cause significant morbidity or mortality.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1977-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  19. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Yen, S. P. S.; Klein, E. (Inventor)

    1976-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, crosslinked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  20. Ion-exchange hollow fibers

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Klein, Elias (Inventor)

    1980-01-01

    An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.

  1. Quartz antenna with hollow conductor

    DOEpatents

    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.

  2. Measurements of Shuttle Glow on Mission STS 41-G

    DTIC Science & Technology

    1988-09-29

    Cogger, I. McDade , E. Murad, and T. Slanger in the preparatioi of this manuscript. REFERENCES Abreu, V. J., W. R. Skinner, P. B. Hays, and J-H. Yee... McDade , S. B. Mende, and G. R. Swenson, Observations of glow from shuttle surfaces during Mission STS 41-G, Planet. Space Sci., 34, 1159-1166, 1986...continuum component, Geophys. Res. Lett., 12, 453-456, 1985. Shepard , G. G., C W. Lake, J. R. Miller, and L. L. Cogger, A spatial spectral scanning

  3. Uncertainty of relative sensitivity factors in glow discharge mass spectrometry

    NASA Astrophysics Data System (ADS)

    Meija, Juris; Methven, Brad; Sturgeon, Ralph E.

    2017-10-01

    The concept of the relative sensitivity factors required for the correction of the measured ion beam ratios in pin-cell glow discharge mass spectrometry is examined in detail. We propose a data-driven model for predicting the relative response factors, which relies on a non-linear least squares adjustment and analyte/matrix interchangeability phenomena. The model provides a self-consistent set of response factors for any analyte/matrix combination of any element that appears as either an analyte or matrix in at least one known response factor.

  4. Radial Distributions of Dusty Plasma Parameters in a Glow Discharge

    SciTech Connect

    Fedoseev, A. V.; Sukhinin, G. I.

    2011-11-29

    A self-consistent model for radial distributions of dusty plasma parameters in a DC glow discharge based on the non-local Boltzmann equation for EEDF, the drift-diffusion equation for ions, and the Poisson equation for self-consistent electric field is presented. The results show that for the case of high dust particles density when the recombination of electrons and ions exceeds the ionization near the tube axis, radial electron and ion fluxes change their direction toward the center of the tube, and the radial electric field is reversed.

  5. Glow Discharge Optical Spectroscopy of Ion Implanted Gallium Arsenide.

    DTIC Science & Technology

    1979-12-01

    a depth profile. Obj ect ives Work on this thesis is a part of the continuing research by thca Air Force Avionics Laboratory. Three specific objec...AD- A *" 413 AIR FORCE INST OF YENf WRIGNT-PATTIRSO APB ON /I GLOV OICHARK OPTICAL SPECTROSCOPY OK SON ZNPLANTID "eLL Up AN-fTC (U) MC 79 S PUWrWTI...8217S THESIS,_ (,/AFIT/GE/EE/79D-2 ~ ~ a t u Approved for public release; distribution unlimited. AFIT/GE/EE/79D-29 GLOW DISCHARGE OPTICAL SPECTROSCOPY

  6. LANL Transfers Glowing Bio Technology to Sandia Biotech

    SciTech Connect

    Rorick, Kevin

    2012-01-01

    Partnering with Los Alamos National Laboratory, an Albuquerque-based company is seeking to transform the way protein and peptide analysis is conducted around the world. Sandia Biotech is using a biological technology licensed from Los Alamos called split green fluorescent protein (sGFP), as a detecting and tracking tool for the protein and peptide industry, valuable in the fields of Alzheimer's research, drug development and other biotechnology fields using protein folding to understand protein expression and mechanisms of action. http://www.lanl.gov/news/stories/glowing-future-for-los-alamos-and-sandia-b iotech-partnership.html

  7. LANL Transfers Glowing Bio Technology to Sandia Biotech

    ScienceCinema

    Rorick, Kevin

    2016-07-12

    Partnering with Los Alamos National Laboratory, an Albuquerque-based company is seeking to transform the way protein and peptide analysis is conducted around the world. Sandia Biotech is using a biological technology licensed from Los Alamos called split green fluorescent protein (sGFP), as a detecting and tracking tool for the protein and peptide industry, valuable in the fields of Alzheimer's research, drug development and other biotechnology fields using protein folding to understand protein expression and mechanisms of action. http://www.lanl.gov/news/stories/glowing-future-for-los-alamos-and-sandia-b iotech-partnership.html

  8. Dual-frequency glow discharges in atmospheric helium

    SciTech Connect

    Huang, Xiaojiang; Guo, Ying; Dai, Lu; Zhang, Jing; Shi, J. J.

    2015-10-15

    In this paper, the dual-frequency (DF) glow discharges in atmospheric helium were experimented by electrical and optical measurements in terms of current voltage characteristics and optical emission intensity. It is shown that the waveforms of applied voltages or discharge currents are the results of low frequency (LF) waveforms added to high frequency (HF) waveforms. The HF mainly influences discharge currents, and the LF mainly influences applied voltages. The gas temperatures of DF discharges are mainly affected by HF power rather than LF power.

  9. Persistence of phosphor glow in microchannel plate image intensifiers

    NASA Technical Reports Server (NTRS)

    Torr, M. R.

    1985-01-01

    Image intensifier tubes using microchannel plate amplification stages and phosphor output stages are being increasingly used in various detection applications. In this paper, measurements of the decay times of what are attributed to be the P20 phosphors in various image intensifiers are reported. It is found that the long tail on the decay curve of the phosphor following illumination can be a limitation for certain observations. In addition, the background level of phosphor glow (which is seen by the subsequent detection system as a light signal) continues to build with continuing illumination.

  10. Core-shell-corona polymeric micelles as a versatile template for synthesis of inorganic hollow nanospheres.

    PubMed

    Sasidharan, Manickam; Nakashima, Kenichi

    2014-01-21

    shell structures-that allow fabrication of a variety of hollow nanoparticles. Importantly, we synthesized all of these particles in water, avoiding use of hazardous organic solvents. We have designed the precursor of the inorganic material to be selectively sorbed into the shell domain, leaving the corona free from the inorganic precursors that would destabilize the micelle. The core, meanwhile, is the template for the formation of the hollow void. By rationally tailoring experimental parameters, we readily and selectively obtained a variety of hollow nanoparticles including silica, hybrid silicas, metal-oxides, metal-carbonates, metal-sulfates, metal-borates, and metal-phosphates. Finally, we highlight the state-of-the-art techniques we used to characterize these nanoparticles, and describe experiments that demonstrate the potential of these hollow particles in drug delivery, and as anode and cathode materials for lithium-ion batteries.

  11. ANODIC TREATMENT OF URANIUM

    DOEpatents

    Kolodney, M.

    1959-02-01

    A method is presented for effecting eloctrolytic dissolution of a metallic uranium article at a uniform rate. The uranium is made the anode in an aqueous phosphoric acid solution containing nitrate ions furnished by either ammonium nitrate, lithium nitrate, sodium nitrate, or potassium nitrate. A stainless steel cathode is employed and electrolysls carried out at a current density of about 0.1 to 1 ampere per square inch.

  12. Nickel anode electrode

    DOEpatents

    Singh, Prabhakar; Benedict, Mark

    1987-01-01

    A nickel anode electrode fabricated by oxidizing a nickel alloying material to produce a material whose exterior contains nickel oxide and whose interior contains nickel metal throughout which is dispersed the oxide of the alloying material and by reducing and sintering the oxidized material to form a product having a nickel metal exterior and an interior containing nickel metal throughout which is dispersed the oxide of the alloying material.

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

    SciTech Connect

    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..

  14. Glow discharge with electrostatic confinement of electrons in a chamber bombarded by fast electrons

    NASA Astrophysics Data System (ADS)

    Metel, A. S.; Grigoriev, S. N.; Melnik, Yu. A.; Prudnikov, V. V.

    2011-07-01

    A metal substrate is immersed in plasma of glow discharge with electrostatic confinement of electrons inside the vacuum chamber volume V ≈ 0.12 m3 filled with argon or nitrogen at pressures 0.005-5 Pa, and dependence of discharge characteristics on negative substrate potential is studied. Emitted by the substrate secondary electrons bombard the chamber walls and it results in electron emission growth of the chamber walls and rise of gas ionization intensity inside the chamber. Increase of voltage U between the chamber and the substrate up to 10 kV at a constant discharge current I d in the anode circuit results in a manifold rise of current I in the substrate circuit and decrease of discharge voltage U d between the anode and the chamber from hundreds to tens of volts. At pressure p < 0.05 Pa nonuniformity of plasma density does not exceed ˜10%. Using the Child-Langmuir law, as well as measurement results of sheath width d between homogeneous plasma and a lengthy flat substrate dependent on voltage U ion current density j i on the substrate surface and ion-electron emission coefficient γ i are calculated. After the current in circuit of a substrate made of the same material is measured, the γ i values may be used to evaluate the average dose of ion implantation. The rate of dose rise at a constant high voltage U is by an order of magnitude higher than in known systems equipped with generators of square-wave high-voltage pulses. Application to the substrate of 10-ms-wide sinusoidal high-voltage pulses, which follow each other with 100-Hz frequency, results in synchronous oscillations of voltage U and ion current I i in the substrate circuit. In this case variation of the sheath width d due to oscillations of U and Ii is insignificant and d does not exceed several centimeters thus enabling substrate treatment in a comparatively small vacuum chamber.

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

    ERIC Educational Resources Information Center

    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…

  16. LOX/Methane Main Engine Glow Plug Igniter Tests and Modeling

    NASA Technical Reports Server (NTRS)

    Breisacher, Kevin; Ajmani, Kumud

    2009-01-01

    Ignition data for tests with a LOX/methane igniter that utilized a glow plug as the ignition source are presented. The tests were conducted in a vacuum can with thermally conditioned (cold) hardware. Data showing the effects of glow plug geometry, type, and igniter operating conditions are discussed. Comparisons between experimental results and multidimensional, transient computer models are also made.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemo-luminescent 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 was used to record glow on vertical tail and OMS pods.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Method of inducing differential etch rates in glow discharge produced amorphous silicon

    DOEpatents

    Staebler, David L.; Zanzucchi, Peter J.

    1980-01-01

    A method of inducing differential etch rates in glow discharge produced amorphous silicon by heating a portion of the glow discharge produced amorphous silicon to a temperature of about 365.degree. C. higher than the deposition temperature prior to etching. The etch rate of the exposed amorphous silicon is less than the unheated amorphous silicon.

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

    ERIC Educational Resources Information Center

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

    PubMed

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

    2014-05-21

    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.

  4. Process for anodizing aluminum foil

    SciTech Connect

    Ball, J.A.; Scott, J.W.

    1984-11-06

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80/sup 0/ C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V.

  5. Optical response in subnanometer hollow sodium nanowires

    NASA Astrophysics Data System (ADS)

    Sun, Bin; Yang, You-chang; Wu, Bo; Ren, Chongdan; Kang, Shuai; Li, Yangjun; Liu, Jian-Qiang

    2017-07-01

    We simulate and analyze the influence of nonlocal effects on the optical properties of thin metal hollow nanowires by finite element method. Nonlocal effects in hollow nanowires with both nm-sized overall volume and a tiny metal shell are considerable for extinction cross section but more for field enhancement, resulting in nonlocal plasmonic modes excited. Then, we show the dependence of extinction effects of a hollow super-nanowire on its parameters, including the metal shell thickness, the average radius and the optical constant of the hollow core. We find that nonlocal quadrupolar mode is very sensitive to the thickness of metal layer but with great stability as increasing the hollow nanowire dimension or changing the hollow core. Furthermore, the eccentricity of the hollow nanowire brings out new physical phenomena, such as nanofocusing and multimodes. The proposed structure promises a great of applications in nanoscale, such as designing nanoplasmonic antenna, sensing and nonlinear optics, etc.

  6. Hollow waveguide cavity ringdown spectroscopy

    NASA Technical Reports Server (NTRS)

    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.

  7. Hollow Plasma in a Solenoid

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-11-30

    A ring cathode for a pulsed, high-current, multi-spot cathodic arc discharge was placed inside a pulsed magnetic solenoid. Photography is used to evaluate the plasma distribution. The plasma appears hollow for cathode positions close the center of the solenoid, and it is guided closer to the axis when the cathode is away from the center.

  8. Emergence and consequences of lateral sample heterogeneity in glow discharge spectrometry

    NASA Astrophysics Data System (ADS)

    Storey, Andrew P.; Ray, Steven J.; Hoffmann, Volker; Voronov, Maxim; Engelhard, Carsten; Buscher, Wolfgang; Hieftje, Gary M.

    2016-12-01

    Conventional glow discharge emission or mass spectrometry requires the assumption that the surface of the sample is homogeneous. However, recent developments in glow discharge imaging appear to offer an opportunity to obtain three-dimensional concentration maps, in which this assumption is no longer necessary. Here, experiments, models, and a summary of earlier work are combined to examine the sputtering behavior of elemental and morphological heterogeneities in a sample. The theoretical model reveals gaps in current knowledge of glow discharge sputtering of heterogeneous samples, particularly indicating that heterogeneity in the sample leads to roughened crater bottoms and how additional morphology can evolve. Additionally, a three-dimensional profiling microscope is used to characterize the effects of surface inclusions on the sputtering process in a DC glow discharge in a reduced-pressure argon environment. Findings have important implications for bulk analysis, depth-profiling, and elemental surface mapping with glow discharge spectrometry.

  9. Demonstration of Separation Control Using Glow-Discharge Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Ashpis, David E.

    2003-01-01

    Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modem low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.

  10. Demonstration of Separation Delay with Glow-Discharge Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Ashpis, David E.

    2004-01-01

    Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2 percent) and high (2.5 percent) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control.

  11. Intrinsic noise induced coherence resonance in a glow discharge plasma

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Experimental evidence of intrinsic noise induced coherence resonance in a glow discharge plasma is being reported. Initially the system is started at a discharge voltage (DV) where it exhibited fixed point dynamics, and then with the subsequent increase in the DV spikes were excited which were few in number and with further increase of DV the number of spikes as well as their regularity increased. The regularity in the interspike interval of the spikes is estimated using normalized variance. Coherence resonance was determined using normalized variance curve and also corroborated by Hurst exponent and power spectrum plots. We show that the regularity of the excitable spikes in the floating potential fluctuation increases with the increase in the DV, up to a particular value of DV. Using a Wiener filter, we separated the noise component which was observed to increase with DV and hence conjectured that noise can play an important role in the generation of the coherence resonance. From an anharmonic oscillator equation describing ion acoustic oscillations, we have been able to obtain a FitzHugh-Nagumo like model which has been used to understand the excitable dynamics of glow discharge plasma in the presence of noise. The numerical results agree quite well with the experimental results.

  12. Simulations of Direct Current Glow Discharges in Supersonic Air Flow

    NASA Astrophysics Data System (ADS)

    Mahadevan, Shankar; Raja, Laxminarayan

    2008-10-01

    In recent years, there have been a significant number of computational and experimental studies investigating the application of plasma discharges as actuators for high speed flow control. The relative importance of the actuation mechanisms: volumetric heating and electrostatic forcing can be established by developing self-consistent models of the plasma and bulk supersonic flow. To simulate the plasma discharge in a supersonic air stream, a fluid model of the glow discharge is coupled with a compressible Navier-Stokes solver in a self-consistent manner. Source terms for the momentum and energy equations are calculated from the plasma model and input into the Navier-Stokes solver. In turn, the pressure, gas temperature and velocity fields from the Navier-Stokes solution are fed back into the plasma model. The results include plasma species number density contour maps in the absence and presence of Mach 3 supersonic flow, and the corresponding effect of the glow discharge on gas dynamic properties such as the gas pressure and temperature. We also examine the effect of increasing the discharge voltage on the structure of the discharge and its corresponding effect on the supersonic flow.

  13. On electron bunching and stratification of glow discharges

    SciTech Connect

    Golubovskii, Yuri B.; Kolobov, Vladimir I.; Nekuchaev, Vladimir O.

    2013-10-15

    Plasma stratification and excitation of ionization waves is one of the fundamental problems in gas discharge physics. Significant progress in this field is associated with the name of Lev Tsendin. He advocated the need for the kinetic approach to this problem contrary to the traditional hydrodynamic approach, introduced the idea of electron bunching in spatially periodic electric fields, and developed a theory of kinetic resonances for analysis of moving striations in rare gases. The present paper shows how Tsendin's ideas have been further developed and applied for understanding the nature of the well-known S-, P-, and R-striations observed in glow discharges of inert gases at low pressures and currents. We review numerical solutions of a Fokker-Planck kinetic equation in spatially periodic electric fields under the effects of elastic and inelastic collisions of electrons with atoms. We illustrate the formation of kinetic resonances at specific field periods for different shapes of injected Electron Distribution Functions (EDF). Computer simulations illustrate how self-organization of the EDFs occurs under nonlocal conditions and how Gaussian-like peaks moving along resonance trajectories are formed in a certain range of discharge conditions. The calculated EDFs agree well with the experimentally measured EDFs for the S, P, and R striations in noble gases. We discuss how kinetic resonances affect dispersion characteristics of moving striations and mention some non-linear effects associated with glow discharge stratification. We propose further studies of stratification phenomena combining physical kinetics and non-linear physics.

  14. Interaction of a surface glow discharge with a gas flow

    SciTech Connect

    Aleksandrov, A. L. Schweigert, I. V.

    2010-05-15

    A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250-300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow's influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.

  15. Dust particle radial confinement in a dc glow discharge.

    PubMed

    Sukhinin, G I; Fedoseev, A V; Antipov, S N; Petrov, O F; Fortov, V E

    2013-01-01

    A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud.

  16. A flexible freestanding Si/rGO hybrid film anode for stable Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Haoxuan; Jing, Shilong; Hu, Yanjie; Jiang, Hao; Li, Chunzhong

    2016-03-01

    The fabrication of flexible freestanding electrodes with superior electrochemical performance is challenging now in consumer electronics miniaturization. Herein, we demonstrate a simple and scalable synthesis of hollow silicon nanosheets, which then hybridizes with rGO into flexible films by layer-by-layer assembly process. The resulting Si/rGO films, when applied as a free-standing LIBs anode, exhibit a high reversible specific capacity of 904 mAh g-1 at 200 mA g-1 (about 2 times higher than theoretical value of graphite anode), and meanwhile maintain a long cycle life (650 mAh g-1 after 150 cycles). In addition, a flexible full battery has also been assembled based on the flexible film as an anode and the commercial LiCoO2 as a cathode, which impressively delivers a high specific capacity of 700 and 613 mAh g-1 at 50 mA g-1 after 15 cycles in flat and bent state, respectively. Such intriguing electrochemical performances can be mainly attributed to the two-dimensional hollow nanostructure of silicon and their strong synergistic effect with rGO. It is reckoned that our Si/rGO films are a promising anode for advanced flexible LIBs.

  17. Rambutan-like FeCO3 hollow microspheres: facile preparation and superior lithium storage performances.

    PubMed

    Zhong, Yiren; Su, Liwei; Yang, Mei; Wei, Jinping; Zhou, Zhen

    2013-11-13

    Rambutan-like FeCO3 hollow microspheres were prepared via a facile and economic one-step hydrothermal method. The structure and morphology evolution mechanism was disclosed through time-dependent experiments. After undergoing the symmetric inside-out Ostwald ripening, the resultants formed microporous/nanoporous constructions composed of numerous one-dimensional (1D) nanofiber building blocks. Tested as anode materials of Li-ion batteries, FeCO3 hollow microspheres presented attractive electrochemical performances. The capacities were over 1000 mAh g(-1) for initial charge, ~880 mAh g(-1) after 100 cycles at 50 mA g(-1), and ~710 mAh g(-1) after 200 cycles at 200 mA g(-1). The 1D nanofiber assembly and hollow interior endow this material efficient contact with electrolyte, short Li(+) diffusion paths, and sufficient void spaces to accommodate large volume variation. The cost-efficient FeCO3 with rationally designed nanostructures is a promising anode candidate for Li-ion batteries.

  18. A dynamic inert metal anode.

    SciTech Connect

    Hryn, J. N.

    1998-11-09

    A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough to maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.

  19. Thin film buried anode battery

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Liu, Ping

    2009-12-15

    A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

  20. Plasma mixing glow discharge device for analytical applications

    DOEpatents

    Pinnaduwage, Lal A.

    1999-01-01

    An instrument for analyzing a sample has an enclosure that forms a chamber containing an anode which divides the chamber into a discharge region and an analysis region. A gas inlet and outlet are provided to introduce and exhaust a rare gas into the discharge region. A cathode within the discharge region has a plurality of pins projecting in a geometric pattern toward the anode for exciting the gas and producing a plasma discharge between the cathode and the anode. Low energy electrons (e.g. <0.5 eV) pass into the analysis region through an aperture. The sample to be analyzed is placed into the analysis region and bombarded by the metastable rare gas atoms and the low energy electrons extracted into from the discharge region. A mass or optical spectrometer can be coupled to a port of the analysis region to analyze the resulting ions and light emission.

  1. Plasma mixing glow discharge device for analytical applications

    DOEpatents

    Pinnaduwage, L.A.

    1999-04-20

    An instrument for analyzing a sample has an enclosure that forms a chamber containing an anode which divides the chamber into a discharge region and an analysis region. A gas inlet and outlet are provided to introduce and exhaust a rare gas into the discharge region. A cathode within the discharge region has a plurality of pins projecting in a geometric pattern toward the anode for exciting the gas and producing a plasma discharge between the cathode and the anode. Low energy electrons (e.g. <0.5 eV) pass into the analysis region through an aperture. The sample to be analyzed is placed into the analysis region and bombarded by the metastable rare gas atoms and the low energy electrons extracted into from the discharge region. A mass or optical spectrometer can be coupled to a port of the analysis region to analyze the resulting ions and light emission. 3 figs.

  2. Conversion Reaction-Based Oxide Nanomaterials for Lithium Ion Battery Anodes.

    PubMed

    Yu, Seung-Ho; Lee, Soo Hong; Lee, Dong Jun; Sung, Yung-Eun; Hyeon, Taeghwan

    2016-04-27

    Developing high-energy-density electrodes for lithium ion batteries (LIBs) is of primary importance to meet the challenges in electronics and automobile industries in the near future. Conversion reaction-based transition metal oxides are attractive candidates for LIB anodes because of their high theoretical capacities. This review summarizes recent advances on the development of nanostructured transition metal oxides for use in lithium ion battery anodes based on conversion reactions. The oxide materials covered in this review include oxides of iron, manganese, cobalt, copper, nickel, molybdenum, zinc, ruthenium, chromium, and tungsten, and mixed metal oxides. Various kinds of nanostructured materials including nanowires, nanosheets, hollow structures, porous structures, and oxide/carbon nanocomposites are discussed in terms of their LIB anode applications.

  3. Sodium ion insertion in hollow carbon nanowires for battery applications.

    PubMed

    Cao, Yuliang; Xiao, Lifen; Sushko, Maria L; Wang, Wei; Schwenzer, Birgit; Xiao, Jie; Nie, Zimin; Saraf, Laxmikant V; Yang, Zhengguo; Liu, Jun

    2012-07-11

    Hollow carbon nanowires (HCNWs) were prepared through pyrolyzation of a hollow polyaniline nanowire precursor. The HCNWs used as anode material for Na-ion batteries deliver a high reversible capacity of 251 mAh g(-1) and 82.2% capacity retention over 400 charge-discharge cycles between 1.2 and 0.01 V (vs Na(+)/Na) at a constant current of 50 mA g(-1) (0.2 C). Excellent cycling stability is also observed at an even higher charge-discharge rate. A high reversible capacity of 149 mAh g(-1) also can be obtained at a current rate of 500 mA g(-1) (2C). The good Na-ion insertion property is attributed to the short diffusion distance in the HCNWs and the large interlayer distance (0.37 nm) between the graphitic sheets, which agrees with the interlayered distance predicted by theoretical calculations to enable Na-ion insertion in carbon materials.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Inward Lithium-Ion Breathing of Hierarchically Porous Silicon Anodes

    SciTech Connect

    Xiao, Qiangfeng; Gu, Meng; Yang, Hui; Li, Bing; Zhang, Cunman; Liu, Yang; Liu, Fang; Dai, Fang; Yang, Li; Liu, Zhongyi; Xiao, Xingcheng; Liu, Gao; Zhao, Peng; Zhang, Sulin; Wang, Chong M.; Lu, Yunfeng; Cai, Mei

    2015-11-05

    Silicon has been identified as one of the most promising candidates as anode for high performance lithium-ion batteries. The key challenge for Si anodes is the large volume change induced chemomechanical fracture and subsequent rapid capacity fading upon cyclic charge and discharge. Improving capacity retention thus critically relies on smart accommodation of the volume changes through nanoscale structural design. In this work, we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. Upon charge/discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward expansion/contraction with negligible particle-level outward expansion. Our mechanics analysis revealed that such a unique volume-change accommodation mechanism is enabled by the much stiffer modulus of the lithiated layer than the unlithiated porous layer and the low flow stress of the porous structure. Such inward expansion shields the hp-SiNSs from fracture, opposite to the outward expansion in solid Si during lithiation. Lithium ion battery assembled with this new nanoporous material exhibits high capacity, high power, long cycle life and high coulombic efficiency, which is superior to the current commercial Si-based anode materials. We find the low cost synthesis approach reported here provides a new avenue for the rational design of hierarchically porous structures with unique materials properties.

  6. Inward Lithium-Ion Breathing of Hierarchically Porous Silicon Anodes

    DOE PAGES

    Xiao, Qiangfeng; Gu, Meng; Yang, Hui; ...

    2015-11-05

    Silicon has been identified as one of the most promising candidates as anode for high performance lithium-ion batteries. The key challenge for Si anodes is the large volume change induced chemomechanical fracture and subsequent rapid capacity fading upon cyclic charge and discharge. Improving capacity retention thus critically relies on smart accommodation of the volume changes through nanoscale structural design. In this work, we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. Upon charge/discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward expansion/contraction with negligible particle-levelmore » outward expansion. Our mechanics analysis revealed that such a unique volume-change accommodation mechanism is enabled by the much stiffer modulus of the lithiated layer than the unlithiated porous layer and the low flow stress of the porous structure. Such inward expansion shields the hp-SiNSs from fracture, opposite to the outward expansion in solid Si during lithiation. Lithium ion battery assembled with this new nanoporous material exhibits high capacity, high power, long cycle life and high coulombic efficiency, which is superior to the current commercial Si-based anode materials. We find the low cost synthesis approach reported here provides a new avenue for the rational design of hierarchically porous structures with unique materials properties.« less

  7. Inward lithium-ion breathing of hierarchically porous silicon anodes

    PubMed Central

    Xiao, Qiangfeng; Gu, Meng; Yang, Hui; Li, Bing; Zhang, Cunman; Liu, Yang; Liu, Fang; Dai, Fang; Yang, Li; Liu, Zhongyi; Xiao, Xingcheng; Liu, Gao; Zhao, Peng; Zhang, Sulin; Wang, Chongmin; Lu, Yunfeng; Cai, Mei

    2015-01-01

    Silicon has been identified as a highly promising anode for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is large volume change during the lithiation/delithiation cycle that results in chemomechanical degradation and subsequent rapid capacity fading. Here we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. On charge/discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward Li breathing with negligible particle-level outward expansion. Our mechanics analysis revealed that such inward expansion is enabled by the much stiffer lithiated layer than the unlithiated porous layer. LIBs assembled with the hp-SiNSs exhibit high capacity, high power and long cycle life, which is superior to the current commercial Si-based anode materials. The low-cost synthesis approach provides a new avenue for the rational design of hierarchically porous structures with unique materials properties. PMID:26538181

  8. Boric/sulfuric acid anodize - Alternative to chromic acid anodize

    NASA Astrophysics Data System (ADS)

    Koop, Rodney; Moji, Yukimori

    1992-04-01

    The suitability of boric acid/sulfuric acid anodizing (BSAA) solution as a more environmentally acceptable replacement of the chromic acid anodizing (CAA) solution was investigated. Results include data on the BSAA process optimization, the corrosion protection performance, and the compatibility with aircraft finishing. It is shown that the BSSA implementation as a substitude for CAA was successful.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Thin flexible intercalation anodes

    SciTech Connect

    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.

  12. Anodic bonded graphene

    NASA Astrophysics Data System (ADS)

    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.

  13. Polytetrafluoroethylene-Impregnated Anodization For Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, Merlin D.

    1990-01-01

    Technical memorandum describes experiments on ability of two commercial coatings and of standard hard anodization to protect aluminum against corrosion. Both commercial coatings, Polylube and Tufram, polytetrafluoroethylene-impregnated anodizations. Standard hard-anodized coating found to provide greatest protection.

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

    PubMed

    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.

  15. Multiple Hollow Cathode Wear Testing

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    1994-01-01

    A hollow cathode-based plasma contactor has been baselined for use on the Space Station to reduce station charging. The plasma contactor provides a low impedance connection to space plasma via a plasma produced by an arc discharge. The hollow cathode of the plasma contactor is a refractory metal tube, through which xenon gas flows, which has a disk-shaped plate with a centered orifice at the downstream end of the tube. Within the cathode, arc attachment occurs primarily on a Type S low work function insert that is next to the orifice plate. This low work function insert is used to reduce cathode operating temperatures and energy requirements and, therefore, achieve increased efficiency and longevity. The operating characteristics and lifetime capabilities of this hollow cathode, however, are greatly reduced by oxygen bearing contaminants in the xenon gas. Furthermore, an optimized activation process, where the cathode is heated prior to ignition by an external heater to drive contaminants such as oxygen and moisture from the insert absorbed during exposure to ambient air, is necessary both for cathode longevity and a simplified power processor. In order to achieve the two year (approximately 17,500 hours) continuous operating lifetime requirement for the plasma contactor, a test program was initiated at NASA Lewis Research Center to demonstrate the extended lifetime capabilities of the hollow cathode. To date, xenon hollow cathodes have demonstrated extended lifetimes with one test having operated in excess of 8000 hours in an ongoing test utilizing contamination control protocols developed by Sarver-Verhey. The objectives of this study were to verify the transportability of the contamination control protocols developed by Sarver-Verhey and to evaluate cathode contamination control procedures, activation processes, and cathode-to-cathode dispersions in operating characteristics with time. These were accomplished by conducting a 2000 hour wear test of four hollow

  16. Mesoporous Silicon-Based Anodes

    NASA Technical Reports Server (NTRS)

    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).

  17. General Synthetic Strategy for Hollow Hybrid Microspheres through a Progressive Inward Crystallization Process.

    PubMed

    Yang, Li-Ping; Lin, Xi-Jie; Zhang, Xing; Zhang, Wei; Cao, An-Min; Wan, Li-Jun

    2016-05-11

    Hollow hybrid microspheres have found great potential in different areas, such as drug delivery, nanoreactors, photonics, and lithium-ion batteries. Here, we report a simple and scalable approach to construct high-quality hollow hybrid microspheres through a previously unexplored growth mechanism. Starting from uniform solid microspheres with low crystallinity, we identified that a hollowing process can happen through the progressive inward crystallization process initiated on the particle surface: the gradual encroachment of the crystallization frontline toward the core leads to the depletion of the center and forms the central cavity. We showed that such a synthetic platform was versatile and can be applicable for a large variety of materials. By using the production of Li4Ti5O12-carbon hollow hybrid microspheres as an example, we demonstrated that high-performance anode materials could be achieved through synthesis and structure control. We expect that our findings offer new perspectives in different areas ranging from materials chemistry, energy storage devices, catalysis, to drug delivery.

  18. Hollow carbon nanofiber-encapsulated sulfur cathodes for high specific capacity rechargeable lithium batteries.

    PubMed

    Zheng, Guangyuan; Yang, Yuan; Cha, Judy J; Hong, Seung Sae; Cui, Yi

    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 Li(2)S 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 LiNO(3) 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.

  19. 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.

    PubMed

    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.

  20. Anode film formation and control

    DOEpatents

    Koski, Oscar; Marschman, Steven C.

    1990-01-01

    A protective film is created about the anode within a cryolite-based electrolyte during electrolytic production of aluminum from alumina. The film function to minimize corrosion of the anode by the cryolitic electrolyte and thereby extend the life of the anode. Various operating parameters of the electrolytic process are controlled to maintain the protective film about the anode in a protective state throughout the electrolytic reduction of alumina. Such parameters include electrolyte temperature, electrolyte ratio, current density, and Al.sub.2 O.sub.3 concentration. An apparatus is also disclosed to enable identification of the onset of anode corrosion due to disruption of the film to provide real time information regarding the state of the film.

  1. Anode film formation and control

    DOEpatents

    Koski, O.; Marschman, S.C.

    1990-05-01

    A protective film is created about the anode within a cryolite-based electrolyte during electrolytic production of aluminum from alumina. The film functions to minimize corrosion of the anode by the cryolitic electrolyte and thereby extend the life of the anode. Various operating parameters of the electrolytic process are controlled to maintain the protective film about the anode in a protective state throughout the electrolytic reduction of alumina. Such parameters include electrolyte temperature, electrolyte ratio, current density, and Al[sub 2]O[sub 3] concentration. An apparatus is also disclosed to enable identification of the onset of anode corrosion due to disruption of the film to provide real time information regarding the state of the film. 3 figs.

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

    PubMed

    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.

  3. Mass dependency of turbulent parameters in stationary glow discharge plasmas

    SciTech Connect

    Titus, J. B.; Alexander, A. B.; Wiggins, D. L.; Johnson, J. A. III

    2013-05-15

    A direct current glow discharge tube is used to determine how mass changes the effects of certain turbulence characteristics in a weakly ionized gas. Helium, neon, argon, and krypton plasmas were created, and an axial magnetic field, varied from 0.0 to 550.0 Gauss, was used to enhance mass dependent properties of turbulence. From the power spectra of light emission variations associated with velocity fluctuations, determination of mass dependency on turbulent characteristic unstable modes, energy associated with turbulence, and the rate at which energy is transferred from scale to scale are measured. The magnetic field strength is found to be too weak to overcome particle diffusion to the walls to affect the turbulence in all four types of plasmas, though mass dependency is still detected. Though the total energy and the rate at which the energy moves between scales are mass invariant, the amplitude of the instability modes that characterize each plasma are dependent on mass.

  4. Measurement of temperature and emissivity of specularly reflecting glowing bodies

    NASA Technical Reports Server (NTRS)

    Hansen, G. P.; Hauge, R. H.; Margrave, J. L.; Krishnan, S.

    1988-01-01

    A new method of measuring the thermodynamic temperature of an object as well as the surface emissivity based on laser reflectivity has been developed. By using rotator analyzer ellipsometry, the light reflected from the sample at a specific angle of incidence can be analyzed for its ellipticity. The normal incidence reflectivity and emissivity are then extracted using standard relations. The thermodynamic temperature of the body is obtained simultaneously by measuring the intensity of emitted light at the same angle of incidence. Room temperature measurements are carried out on selected metals to test the system. Elevated temperature measurements on platinum foils show that this technique is reliable and accurate for monitoring and measuring the temperature and emissivity of specularly reflecting, glowing bodies.

  5. Improved performance of a quadrupole based glow discharge mass spectrometer

    SciTech Connect

    Valiga, R.E.; Duckworth, D.C.; Smith, D.H.

    1995-12-31

    Glow discharge mass spectrometry (GDMS) has experienced most of its commercial success in trace multi-element analysis using sector-based mass spectrometry. In most cases, the mass resolution available with these instruments allows elements of interest to be analyzed, even in the presence of polyatomic interferences (e.g., ArC+, ArN+, ArO+). Because quadrupole mass filters have little more than unit resolution, background equivalent concentrations (BEC`s) for many elements can be quite high (1-100 ppm). Because of this, many have discounted quadrupole GDMS as a useful trace analysis technique. In this work, the authors have explored methods of reducing the polyatomic interferences.

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

    SciTech Connect

    Xu, Liang Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi; Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang

    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.

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

    PubMed

    Xu, Liang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi; Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang

    2014-09-01

    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.

  8. Probiotic Bacteria Induce a ‘Glow of Health’

    PubMed Central

    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

  9. Measurement of temperature and emissivity of specularly reflecting glowing bodies

    NASA Technical Reports Server (NTRS)

    Hansen, G. P.; Hauge, R. H.; Margrave, J. L.; Krishnan, S.

    1988-01-01

    A new method of measuring the thermodynamic temperature of an object as well as the surface emissivity based on laser reflectivity has been developed. By using rotator analyzer ellipsometry, the light reflected from the sample at a specific angle of incidence can be analyzed for its ellipticity. The normal incidence reflectivity and emissivity are then extracted using standard relations. The thermodynamic temperature of the body is obtained simultaneously by measuring the intensity of emitted light at the same angle of incidence. Room temperature measurements are carried out on selected metals to test the system. Elevated temperature measurements on platinum foils show that this technique is reliable and accurate for monitoring and measuring the temperature and emissivity of specularly reflecting, glowing bodies.

  10. A Sample Glows as it Melts within TEMPUS

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This video was taken from the first flight of the TEMPUS electromagnetic levitation furnace on the International Microgravity Laboratory-2 (STS-65, July 8-23, 1994). This view is from the furnace's upper camera and shows a sample glowing as it melts. TEMPUS (stands for Tiegelfreies Elektromagnetisches Prozessiere unter Schwerelosigkeit (containerless electromagnetic processing under weightlessness). It was developed by the German Space Agency (DARA) for flight aboard Spacelab. The DARA project scientist was Igon Egry. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). DARA and NASA are exploring the possibility of flying an advanced version of TEMPUS on the International Space Station. (200KB JPEG, 1267 x 1931 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300195.html.

  11. Compact lanthanum hexaboride hollow cathode.

    PubMed

    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.

  12. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

    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.

  13. Oxide nanostructures hyperbranched with thin and hollow metal shells for high-performance nanostructured battery electrodes.

    PubMed

    Xia, Xinhui; Xiong, Qinqin; Zhang, Yongqi; Tu, Jiangping; Ng, Chin Fan; Fan, Hong Jin

    2014-06-25

    High-performance electrochemical energy storage (EES) devices require the ability to modify and assemble electrode materials with superior reactivity and structural stability. The fabrication of different oxide/metal core-branch nanoarrays with adjustable components and morphologies (e.g., nanowire and nanoflake) is reported on different conductive substrates. Hollow metal branches (or shells) wrapped around oxide cores are realized by electrodeposition using ZnO nanorods as a sacrificial template. In battery electrode application, the thin hollow metal branches can provide a mechanical protection of the oxide core and a highly conductive path for charges. As a demonstration, arrays of Co3O4/Ni core-branch nanowires are evaluated as the anode for lithium ion batteries. The thin metal branches evidently improve the electrochemical performance with higher specific capacity, rate capability, and capacity retention than the unmodified Co3O4 counterparts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Trace elements in coal by glow discharge mass spectrometry

    SciTech Connect

    Jacobs, M.L.; Wilson, C.R.; Pestovich, J. Jr.

    1995-08-01

    A need and a demand exist for determining trace elements in coal and coal related by-products, especially those elements which may potentially be a health hazard. The provisions of the 1990 clean air act require that the EPA evaluate the emissions of electric utilities for trace elements and other potentially hazardous organic compounds. The coal fired electric utility industry supplies roughly 60% of the total generating capacity of 2,882,525 million kilowatt hours (nearly 3 trillion kilowatt hours) generated in the U.S. This is accomplished by 414 power plants scattered across the country that burned 813,508,000 short tons of coal in 1993. The relative volatility of some inorganic constituents in coal makes them more prone to be emitted to the atmosphere following combustion. The production of analytical data for trace elements is known to be a difficult task in coal and by-products of coal combustion (fly ash, bottom ash, gas streams, etc.), in terms of both sample collection and analytical determinations. There are several common analytical methods available to the analyst to determine trace elements in coal and coal by-products. In general analytical germs, the material to be analyzed can be totally solubilized (or extracted), or the elements analytes can be determined in the material as a solid. A relatively new elemental technique, Glow Discharge Mass Spectrometry (GDMS) can be used with solids as well. This new analytical technique had never before been applied directly to coal. The radio frequency-glow discharge quadropole mass spectrometer was used to analyze coal directly for the first time ever by rf-GDMS. The rf-GDMS technique is described.

  16. Purification of nanoparticles by hollow fiber diafiltration

    NASA Astrophysics Data System (ADS)

    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.

  17. New strategy to the controllable synthesis of CuInS{sub 2} hollow nanospheres and their applications in lithium ion batteries

    SciTech Connect

    Zhang Weixin; Zeng Hui; Yang Zeheng; Wang Qiang

    2012-02-15

    A new strategy has been presented to the controllable synthesis of CuInS{sub 2} hollow nanospheres based on the Cu{sub 2}O solid nanospheres as the precursor in the absence of any surfactant. Specifically, the CuInS{sub 2} hollow nanospheres result from hydrothermal transformation of the intermediate Cu{sub 7}S{sub 4} hollow nanospheres derived from Cu{sub 2}O solid nanosphere precursor by the Kirkendall effect in the conversion process. The CuInS{sub 2} hollow nanospheres with diameters of about 250 nm are assembly of nanoparticles with an average size of 20-30 nm. The composition, structure, and morphology of the Cu{sub 2}O precursor, the Cu{sub 7}S{sub 4} intermediate, and final CuInS{sub 2} product have been, respectively, characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Different from investigation of photovoltaic properties, in this work, the as-prepared CuInS{sub 2} hollow nanospheres have been explored as anode materials for rechargeable lithium ion batteries. They deliver a large initial discharge capacity of 1144 mAh g{sup -1} and exhibit good cycle performance with a discharge capacity of 265 mAh g{sup -1} after 20 cycles, which are superior to those of CuInS{sub 2} nanoparticles. The suitable surface area and relatively stable structure of the CuInS{sub 2} hollow nanospheres play an important role in their enhanced electrochemical performance as anode materials. - Graphical abstract: CuInS{sub 2} hollow nanospheres was successfully prepared from Cu{sub 2}O solid nanospheres in the absence of any surfactant, which can deliver a large initial discharge capacity of 1144 mAh g{sup -1} and exhibit good cycle performance. Highlights: Black-Right-Pointing-Pointer CuInS{sub 2} hollow nanospheres were synthesized hydrothermally from Cu{sub 2}O nanospheres. Black-Right-Pointing-Pointer The CuInS{sub 2} hollow nanospheres present

  18. Medium resolution spectra of the shuttle glow in the visible region of the spectrum

    NASA Technical Reports Server (NTRS)

    Viereck, R. A.; Murad, E.; Pike, C. P.; Mende, S. B.; Swenson, G. R.; Culbertson, F. L.; Springer, B. C.

    1992-01-01

    Recent spectral measurements of the visible shuttle glow (lambda = 400 - 800 nm) at medium resolution (1 nm) reveal the same featureless continuum with a maximum near 680 nm that was reported previously. This is also in good agreement with recent laboratory experiments that attribute the glow to the emissions of NO2 formed by the recombination of O + NO. The data that are presented were taken from the aft flight deck with a hand-held spectrograph and from the shuttle bay with a low-light-level television camera. Shuttle glow images and spectra are presented and compared with laboratory data and theory.

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

    SciTech Connect

    Bo, Zheng; Qian, Jiajing; Duan, Liangping; Qiu, Kunzan Yan, Jianhua; Cen, Kefa; Han, Zhao Jun; Ostrikov, Kostya

    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.

  20. Determination of the plasma impedance of a glow discharge in carbon dioxide

    NASA Astrophysics Data System (ADS)

    Kiselev, A. S.; Smirnov, E. A.

    2017-07-01

    In this work an expression for the dynamic resistance of a glow discharge flowing in long tubes is obtained and analyzed. The expression describes the physical processes occurring in the positive column of a glow discharge. The frequency dependences of the active and reactive components as well as the dynamic resistance module for the discharge conditions corresponding to CO2-lasers have been calculated. Based on the simulation results developed a computer program in the C# programming language for modeling the dynamic resistance discharge of glow discharge lasers.

  1. Efficiency of surface cleaning by a glow discharge for plasma spraying coating

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Kashapov, N. F.; Sharifullin, S. N.; Saifutdinov, A. I.; Fadeev, S. A.

    2016-06-01

    The article presents the results of experimental studies of the quality of cleaning steel surfaces by a glow discharge for plasma spraying. Shows the results of measurements of the angle of surface wetting and bond strength of the plasma coating to the surface treated. The dependence of the influence of the glow discharge power, chamber pressure, distance between the electrodes and the processing time of the surface on cleaning efficiency. Optimal fields of factors is found. It is shown increase joint strength coating and base by 30-80% as a result of cleaning the substrate surface by a glow discharge plasma spraying.

  2. Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source

    NASA Astrophysics Data System (ADS)

    Yang, Manman; Wang, Zongyuan; Wang, Wei; Liu, Chang-jun

    2014-08-01

    Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl4 and PdCl2 on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles.

  3. Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source.

    PubMed

    Yang, Manman; Wang, Zongyuan; Wang, Wei; Liu, Chang-Jun

    2014-01-01

    Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl4 and PdCl2 on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles.

  4. Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source

    PubMed Central

    2014-01-01

    Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl4 and PdCl2 on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles. PMID:25177221

  5. Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

    SciTech Connect

    Kaur, Manjit Bose, Sayak; Chattopadhyay, P. K.; Sharma, D.; Ghosh, J.; Saxena, Y. C.; Thomas, Edward

    2015-09-15

    Observation of two well-separated dust vortices in an unmagnetized parallel plate DC glow discharge plasma is reported in this paper. A non-monotonic radial density profile, achieved by an especially designed cathode structure using a concentric metallic disk and ring of different radii, is observed to produce double dust tori between cathode and anode. PIV analysis of the still images of the double tori shows oppositely rotating dust structures between the central disk and the ring. Langmuir probe measurements of background plasma shows a non-uniform plasma density profile between the disk and the ring. Location and sense of rotation of the dust vortices coincides with the location and direction of the radial gradient in the ion drag force caused by the radial density gradient. The experimentally observed dust vorticity matches well with the calculated one using hydrodynamic formulations with shear in ion drag dominating over the dust charge gradient. These results corroborate that a radial gradient in the ion drag force directed towards cathode is the principal cause of dust rotation.

  6. Process for making hollow carbon spheres

    DOEpatents

    Luhrs, Claudia C.; Phillips, Jonathan; Richard, Monique N.; Knapp, Angela Michelle

    2013-04-16

    A hollow carbon sphere having a carbon shell and an inner core is disclosed. The hollow carbon sphere has a total volume that is equal to a volume of the carbon shell plus an inner free volume within the carbon shell. The inner free volume is at least 25% of the total volume. In some instances, a nominal diameter of the hollow carbon sphere is between 10 and 180 nanometers.

  7. HOLLOW CATHODES IN NEGATIVE-GRID TUBES,

    DTIC Science & Technology

    This study involved factors important to the successful operation of hollow cathodes in negative-grid tubes: (1) activation rate; (2) mechanism of...operation; and (3) grid action with truncated pyramidal hollow cathodes. A method of reducing the activation rate by ten-fold was investigated and...et als. Unusual grid-control characteristics associated with hollow cathodes were experimentally derived and indicated the basis for the observed transconductance limitation. (Author)

  8. Method to fabricate hollow microneedle arrays

    DOEpatents

    Kravitz, Stanley H.; Ingersoll, David; Schmidt, Carrie; Flemming, Jeb

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

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

    PubMed

    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.

  10. Electrochemical Study of Hollow Carbon Nanospheres as High-Rate and Low Temperature Negative Electrodes for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Cox, Jonathan David

    The continued advancements in portable electronics have demanded more advanced power sources. To date, lithium ion batteries have been the state-of-the-art for portable devices. One significant drawback of lithium ion batteries is the slow charging times and their performance at low temperatures. In this dissertation, we explore the electrochemical behavior of a new lithium ion, negative electrode active material, hollow carbon nanospheres (HCNS). HCNS are ˜50 nm in diameter hollow spheres with ˜5 - 10 nm graphic walls which have a nominal reversible capacity of ˜220 mAh/g. We assembled and cycled HCNS as a lithium ion anode material and compared it to graphite, currently used as the anode material in most commercial lithium ion batteries. The charging mechanism of HCNS is an intercalation of the lithium ions into the graphitic walls of the spheres, similar to graphite, determined by diffraction and electroanalytical techniques. However, the HCNS electrodes cycled at much higher charge and discharge rates than graphite. Additionally, we demonstrated HCNS cycling at low temperatures (-20 *C) in electrolytes not obtainable by graphite due to material exfoliation during cycling. Although, due to the large surface area of HCNS, the first cycle coulombic losses are very high. This work has resulted in an understanding of a potentially new lithium ion battery anode material with significantly better cycling attributes than the current anode material.

  11. Multi-anode ionization chamber

    DOEpatents

    Bolotnikov, Aleksey E.; Smith, Graham; Mahler, George J.; Vanier, Peter E.

    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.

  12. The anodic passivation of lithium

    SciTech Connect

    James, S.D.

    1983-10-01

    The anodic passivation of Li has been characterized at room temperature in a variety of electrolytes (propylene carbonate, thionyl chloride, sulfur dioxide), as a function of convection and current density and in the presence of water and other impurities. In thionyl chloride the effect of salt concentration (0.5-4.5M, LiA1C1/sub 4/) and acidity (0.5-3M, A1C1/sub 3/) has been studied. The evidence accumulated suggests that anodic passivation is caused by anodic enrichment and eventual precipitation of electrolyte salt in superficial anolyte.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Synthesis of Single-Walled Carbon Nanotubes in a Glow Discharge Fine Particle Plasma

    SciTech Connect

    Imazato, N.; Imano, M.; Hayashi, Y.

    2008-09-07

    Carbon fine particles were synthesized being negatively charged and confined in a glow discharge plasma. The deposited fine particles were analyzed by Raman spectroscopy and transmission electron microscopy (TEM) and were confirmed to include single-walled carbon nanotubes.

  15. Structural analysis of hollow blades: Torsional stress analysis of hollow fan blades for aircraft jet engines

    NASA Technical Reports Server (NTRS)

    Ogawa, A.; Sofue, Y.; Isobe, T.

    1979-01-01

    A torsional stress analysis of hollow fans blades by the finite element method is presented. The fans are considered to be double circular arc blades, hollowed 30 percent, and twisted by a component of the centrifugal force by the rated revolution. The effects of blade hollowing on strength and rigidity are discussed. The effects of reinforcing webs, placed in the hollowed section in varying numbers and locations, on torsional rigidity and the convergence of stresses, are reported. A forecast of the 30 percent hollowing against torsional loadings is discussed.

  16. Parallel vacuum arc discharge with microhollow array dielectric and anode

    SciTech Connect

    Feng, Jinghua; Zhou, Lin; Fu, Yuecheng; Zhang, Jianhua; Xu, Rongkun; Chen, Faxin; Li, Linbo; Meng, Shijian

    2014-07-15

    An electrode configuration with microhollow array dielectric and anode was developed to obtain parallel vacuum arc discharge. Compared with the conventional electrodes, more than 10 parallel microhollow discharges were ignited for the new configuration, which increased the discharge area significantly and made the cathode eroded more uniformly. The vacuum discharge channel number could be increased effectively by decreasing the distances between holes or increasing the arc current. Experimental results revealed that plasmas ejected from the adjacent hollow and the relatively high arc voltage were two key factors leading to the parallel discharge. The characteristics of plasmas in the microhollow were investigated as well. The spectral line intensity and electron density of plasmas in microhollow increased obviously with the decease of the microhollow diameter.

  17. Enhanced IR hollow cathode laser in a 3He Ne gas mixture

    NASA Astrophysics Data System (ADS)

    Stefanova, M. S.; Pramatarov, P. M.; Karelin, A. V.

    2005-09-01

    An experimental and theoretical study on 3He-Ne and 4He-Ne helical hollow cathode lasers is presented. Enhanced laser operation on the near IR NeI lines is observed when the natural isotope 4He is substituted by the lighter isotope 3He. A four-fold increase in the laser output power and a three-fold increase in the laser gain for the strongest NeI 1.1523 µm line is measured in the 3He-Ne gas mixture compared to the 4He-Ne gas mixture. On the basis of the theoretical analysis done by means of a non-stationary kinetic model for the negative glow plasma of 3He-Ne and 4He-Ne hollow cathode lasers, a study on the changes in the particle kinetics is carried out and an explanation of the experimental results is proposed. In the 3He-Ne mixture the electron temperature is lower than in the 4He-Ne mixture, while the gas temperature is higher. As a result the helium triplet metastable density and the rate constant for excitation transfer to neon atoms are higher in the 3He-Ne mixture. The lower laser level de-excitation due to intra-multiplet mixing of 2p1-10levels by 3He atoms is more efficient.

  18. Simultaneous multielement detection in particle beam/hollow cathode-optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Quarles, C. Derrick, Jr.; Marcus, R. Kenneth

    2009-11-01

    Presented here is the development of a particle beam/hollow cathode-optical emission spectroscopy source that has been interfaced with a high resolution polychromator for use as a species-specific detector for chromatographic separations. Use of the high resolution JY RF-5000 polychromator allows simultaneous, multielement analysis; a necessary requirement for comprehensive speciation analysis. Parametric optimization was performed for the nebulization conditions, desolvation temperature, glow discharge current and pressure, and the source block temperature (vaporization) using nitrate salts containing lead, nickel, and silver. Peak area, height, and width were recorded for optical emission of Pb (I) 220.35 nm, Ni (I) 341.41 nm, and Ag (I) 338.28 nm in order to determine optimal peak characteristics under chromatographic separation conditions. Response curves for a multielement salt solution containing Pb, Ni, and Ag were obtained using the optimized conditions, with detection limits for triplicate injections of 2.2, 0.17, and 0.19 ng, respectively. The ability to monitor multiple elements simultaneously reveals the existence of interelement matrix effects that have not been noted previously in hollow cathode devices. The ability to monitor metals and non-metals is demonstrated towards the future application of this system as a tool for metallomic studies.

  19. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  20. Kinetic parameters, bleaching and radiation response of thermoluminescence glow peaks separated by deconvolution on Korean calcite

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Bum; Hong, Duk-Geun

    2014-10-01

    Calcite has been of particular interest in studies of thermoluminescence (TL) because of its geological and archeological importance. Although extensive research on the TL glow curves of calcite has been conducted, most previous works have been based on the TL intensity integrated over a particular temperature range on the glow curve, without any separation of peaks. In this paper, the physical characteristics of the overlapping peaks in the TL glow curves of a calcite sample are investigated. These properties can provide useful information for determining the radiation dose absorbed to the sample in radiation dosimetry and luminescence dating research. The Tm-Tstop method is employed to identify the number of hidden glow peaks, and the kinetic parameters of each separated glow peak, including the thermal activation energy, kinetic order, and frequency factor, are evaluated using a computerized glow curve deconvolution (CGCD) method. The Tm-Tstop method indicates that the glow curve of calcite is the superposition of at least four components (P1 - P4) in the temperature range between room temperature and 450 °C. A bleaching experiment for two separated glow peaks (P3 and P4) using a solar simulator revealed that the bleaching rates of peak P3 show two exponential decays, and after bleaching, the TL intensity of peak P3 is reduced to approximately 4% of the initial value. In contrast, peak P4 is bleached exponentially to approximately 30% of the initial TL intensity and thereafter shows no detectable change in intensity. In addition, in a study of the radiation dose response of the two peaks, both peaks have a similar pattern, exhibiting a linear increment up to the maximum dose investigated, 520 Gy.